Note: Descriptions are shown in the official language in which they were submitted.
CA 02783217 2012-06-29
1
CONVEYOR OVEN APPARATUS AND METHOD
[0001] Blank
BACKGROUND OF THE INVENTION
[00021 A conveyor oven is an oven with a conveyor that moves through a heated
tunnel in
the oven. Conveyor ovens are widely used for baking food products, especially
pizzas, and
the like. Examples of such ovens are shown, for example, in U.S. Pat. Nos.
5,277,105,
6,481,433 and 6,655,373.
[0003] Conveyor ovens are typically large metallic housings with a heated
tunnel extending
through them and a conveyor running through the tunnel. Usually such conveyor
ovens are
either 70 inches or 55 inches long, although they may be constructed in any
suitable size.
The conveyor transports food products through the heated oven tunnel at a
speed which
bakes food products during their transit through the tunnel. The conveyor
ovens include a
heat delivery system including blowers which supply heat to the tunnel from a
plenum
through passageways leading to metal fingers opening into the oven tunnel, at
locations
above and below the conveyor. The metal fingers act as airflow channels that
deliver
streams of hot air which impinge upon the surfaces of the food products
passing through the
tunnel on the conveyor. In modern conveyor ovens, a microprocessor-driven
control panel
generally enables the user to regulate the heat, the speed of the conveyor,
etc., to properly
bake the food product being transported through the oven.
[0004] The conveyor generally travels at a speed calculated to properly bake
food products
on the belt during the time period required for the conveyor to carry them
through the entire
length of the oven tunnel. Other food products requiring less time to bake may
be placed on
the conveyor at a point part way through the oven so that they travel only a
portion of the
CA 02783217 2012-06-29
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length of the tunnel. A pizza is an example of a product which might require
the full amount
of baking time in order to be completely baked in the oven. A sandwich is an
example of a
product which might require only a portion of the full baking time.
[0005] Conveyor ovens are typically used in restaurant kitchens and commercial
food
manufacturing facilities. Typically they are kept running for extended periods
of time,
including periods when products are not being baked. Since the inlet and
outlet ends of the
oven are open, this means that heat and noise are continuously escaping from
the conveyor
oven tunnel into the surrounding environment. This escape of heat wastes
energy. It also
warms the surrounding environment, usually unnecessarily and often to
uncomfortable
levels. This is particularly the case where the conveyor oven is being used in
relatively
cramped restaurant kitchen environments. The escaping noise is also
undesirable since it
may interfere with interpersonal communication among those working near the
oven.
[0006] Conventional conveyor ovens also provide users with limited ability to
reduce
energy losses while running at less than full capacity. Typically, users only
have the ability
to turn such ovens on or off, which in many cases involves an unacceptably
long shut-down
and/or start-up times. Therefore, it is necessary to leave such ovens on
despite the waste of
fuel or other energy supplied to the ovens when cooking food intermittently.
It is not
uncommon for a conventional conveyor oven to be left running in a full
production mode
for substantially the entire period of time a restaurant or other cooking
facility is open.
[0007] It is generally desirable to maintain uniform heating from one end of
the heated
tunnel of the oven to the other. Among the challenges to be overcome in
achieving such
uniform heating are the inherent variations in heating from oven to oven due
to variations in
the internal physical environment of otherwise identical ovens. A more
significant
challenge to maintaining uniform heating through the length of the heated
tunnel is the
constantly changing physical and thermal configuration of the tunnel as food
products being
baked pass from one end of the tunnel to the other. For example, raw pizzas
entering the
inlet to the tunnel constantly change the physical and thermal configuration
of the tunnel
environment as they advance to the other end while drawing and emitting ever-
varying
CA 02783217 2012-06-29
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amounts of heat. As a result, temperatures can vary by as much as 50-60 F from
one end of the
tunnel to the other.
[0008] Currently, the most common technique for balancing the heating through
the length of
the tunnel involves monitoring temperatures near the inlet and outlet ends of
the heated tunnel
to maintain a predetermined average temperature over the length of the tunnel.
Thus, for
example, as a cold raw pizza enters the inlet to the tunnel causing a sudden
drop in the tunnel
temperature at the inlet, the drop in temperature is sensed and more heat is
supplied to the
tunnel to raise the temperature near the inlet heat sensor. Unfortunately,
this also raises the
temperature at the outlet of the oven, which causes the heat sensor at the
outlet to trigger a
heating reduction to prevent an excessive temperature at the oven outlet. In
this way,
temperature sensors near the inlet and outlet of the oven help to balance the
heating of the
tunnel to generally maintain a target average temperature.
[0009] However, uniform heating through the length of the heated tunnel cannot
be achieved in
this way. Thus, food products traveling through the oven do not see uniform
heating which, it
has been discovered, makes it necessary to slow the conveyor to a speed which
completes the
baking in more time than would be the case if uniform heating could be
achieved throughout the
length of the heated tunnel. In other words, improved heating uniformity from
one end of the
tunnel to the other may reduce required baking times.
[0010] Additionally, in many applications it is necessary to be able to
operate the conveyor
oven using either side as the inlet, by running the conveyor belt either from
left-to-right for a
left side inlet, or from right-to-left for a right side inlet. To be most
successful in such
interchangeable applications, it is particularly desirable to produce a
uniform temperature from
one end of the heated tunnel to the other.
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BRIEF SUMMARY OF THE INVENTION
[0011] In one aspect, the present invention provides a conveyor oven having a
first
mode and a second mode of operation. The oven has a tunnel in which food is
cooked
and the conveyor is movable to convey the food through the tunnel. A first set
of one or
more burners is configured to generate heat for the tunnel and the first set
of one or
more burners is operable at a first output during the first mode of operation
and is
variable to a different output in the second mode of operation. A second set
or one or
more burners is configured to generate heat for the tunnel. The second set or
one or
more burners operate at a first output during the first mode of operation and
is turned
off in the second mode of operation. The oven also includes a controller
responsive to
the detection of the absence of food in the tunnel, the controller being
configured to
change operation of the first set or one or more burners and the second set of
one or
more burners from the first mode of operation to the second mode of operation
based at
least in part upon the detection of the absence of food product in the tunnel.
[0012] In another aspect, the invention provides a conveyor oven having a
first mode
and a second mode of operation. The conveyor oven has a tunnel in which food
is
cooked and the conveyor is movable to convey the food through the tunnel. A
first set
of one or more burners is configured to generate heat for the tunnel. A first
valve is
configured to regulate the flow of gas to the first set of one or more
burners. Gas flows
through the first valve at a first flow rate during the first mode of
operation and is
variable to a different flow rate during the second mode of operation, wherein
the first
valve allows at least some gas to flow therethrough at a different flow rate.
A second
set of one or more burners is configured to generate heat for the tunnel. A
second valve
is configured to regulate the flow of gas to the second set or one or more
burners. Gas
flows through the second valve at a first flow rate during the first mode of
operation and
is prevented from flowing therethrough during the second mode of operation.
The oven
also includes a controller responsive to a signal associated with the absence
of food in
CA 02783217 2012-06-29
the tunnel. The controller adjusts to the first valve and the second valve
between the
first mode of operation and the second mode of operation, based at least in
part, upon
the signal.
[0013] In still further aspect, the invention provides a conveyor oven for
cooking food
product having a first and second mode of operation. The oven has a tunnel in
which
food is cooked and a conveyor for moving food through the tunnel. A heat
source
generates the heat to be provided to the tunnel and comprises a first set of
one or more
burners and a second set of one or more burners. A fan operates to move air in
the
tunnel. The oven also comprises at least one controller that controls at least
one of the
fan and the heat source. The controller is responsive to the detection of the
absence of
food from the tunnel to change the oven from the first mode of operation to
the second
mode of operation. In the second mode of operation, the fan moves air in the
tunnel at a
speed that is reduced from the speed of the fan when the oven was in the first
mode of
operation, the output of the first set of one or more burners is adjusted to
maintain the
oven at a steady state temperature, and the second set of burners is turned
off.
[0014] Blank
[0015] Blank
[0016] Blank
[0017] Further aspects of the present invention, together with the
organization and
operation thereof, will become apparent from the following detailed
description of the
invention when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Preferred embodiments of the invention are shown in the attached
drawings, in
which:
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[00191 FIGURE 1 is a perspective view of a conveyor oven in accordance with an
embodiment of the present invention;
[0020] FIGURE 2 is a perspective view of a portion of the conveyor oven of
Figure 1, in
which a hinged oven access panel has been opened to reveal some of the
internal workings
of the oven;
[00211 FIGURE 3 is an enlarged elevation view of an embodiment of the controls
of the
oven of Figure 1;
[0022] FIGURE 3A is a schematic illustration of an embodiment of the control
system of
the conveyor oven of Figure 1;
[0023] FIGURE 4 is a diagrammatic representation of the tunnel of the oven of
Figure 1,
apportioned into two segments with independent temperature sensing and
independent heat
delivery means;
[00241 FIGURES 5A-5C include a diagrammatic representation of a pizza moving
through
the heated tunnel of the conveyor oven of Figure 1, with graphs showing
changing BTU
burner output and blower output as the pizza advances through the tunnel;
[0025] FIGURE 6 is a diagrammatic representation of a single burner of a
contiguous
multiple burner configuration in accordance with an embodiment of the present
invention;
[0026] FIGURE 6A illustrates a venturi support disk of the burner of Figure 6;
[00271 FIGURE 6B illustrates a flame retention member of the venturi tube of
the burner of
Figure 6;
[0028] FIGURES 7A and 7B are perspective views of a pair of contiguous burners
in
accordance with an embodiment of the present invention;
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100291 FIGURE 8 shows the distal ends of the outer tubes of the burners of
Figures 7A -
7B;
[00301 FIGURES 9 - 9D illustr4-- crossover openings between the contiguous
burners of
Figures 7A - 7B;
[00311 FIGURE 10 illustrates an alternative dual contiguous burner
configuration in
accordance with an embodiment the present invention; and
[0032] FIGURE 11 is a top plan view of selected elements of the oven of Figure
1.
[00331 FIGURE 12 is a flowchart illustrating an energy management mode for the
conveyor
oven of FIGURE 1.
[00341 FIGURE 13 is a flowchart illustrating an energy management mode for the
conveyor oven of FIGURE 1.
[0035] FIGURE 14 is a flowchart illustrating an energy management mode for the
conveyor
oven of FIGURE 1.
[00361 FIGURE 15 is a flowchart illustrating a combination of the energy
management
modes illustrated in FIGURES 12 and 13 for the conveyor oven of FIGURE 1.
[00371 FIGURE 16 is a flowchart illustrating a combination of the energy
management
modes illustrated in FIGURES 12, 13, and 14 for the conveyor oven of FIGURE 1.
[0038] FIGURE 17 is a schematic illustration of an alternative embodiment of
the control
system of the conveyor oven of FIGURE 1.
[0039] FIGURE 18A illustrates an embodiment of a main screen of an operator
interface for
the control system illustrated in FIGURE 17.
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[00401 FIGURE 18B illustrates another embodiment of a main screen of an
operator
interface for the control system illustrated in FIGURE 17.
[00411 FIGURE 19 illustrates r..-_ embodiment of a temperature setting screen
of an operator
interface for the control system illustrated in FIGURE 17.
[00421 FIGURE 20 illustrates an embodiment of a temperature tuning screen of
an operator
interface for the control system illustrated in FIGURE 17.
[00431 FIGURE 21A illustrates an embodiment of a belt tuning screen of an
operator
interface for the control system illustrated in FIGURE 17.
[00441 FIGURE 21 B illustrates another embodiment of a belt tuning screen of
an operator
interface for the control system illustrated in FIGURE 17.
[00451 FIGURE 22 illustrates an embodiment of a belt set-up screen of an
operator
interface for the control system illustrated in FIGURE 17.
[00461 FIGURES 23A, 23B, and 23C illustrate an embodiment of energy savings
mode set-
up screens of an operator interface for the control system illustrated in
FIGURE 17.
[00471 FIGURE 24 is an example of a food service floor plan showing a
controller for a
conveyor oven connected to several remote devices.
[00481 FIGURES 25A and B are examples of time lines of conveyor oven operation
based
on indications from one or more remote devices.
DETAILED DESCRIPTION
[00491 Before any embodiments of the invention are explained in detail, it is
to be
understood that the invention is not limited in its application to the details
of construction
and the arrangement of components set forth in the following description or
illustrated in
the following drawings. The invention is capable of other embodiments and of
being
CA 02783217 2012-06-29
9
practiced or of being carried out in various ways. Also, it is to be
understood that the
phraseology and terminology used herein is for the purpose of description and
should not be
regarded as limiting. The use of "including," "comprising," or "having" and
variations
thereof herein is meant to encoi pass the items listed thereafter and
equivalents thereof as
well as additional items. Unless limited otherwise, the terms "connected,"
"coupled," and
"mounted" and variations thereof herein are used broadly and encompass direct
and indirect
connections, couplings, and mountings; and the terms "connected" and "coupled"
and
variations thereof are not restricted to physical or mechanical connections or
couplings.
Also, it is to be understood that phraseology and terminology used herein with
reference to
device or element orientation (such as, for example, terms like "front",
"back", "up",
"down", "top", "bottom", and the like) are only used to simplify description
of the present
invention, and do not alone indicate or imply that the device or element
referred to must
have a particular orientation. In addition, terms such as "first", "second",
and "third" are
used herein and in the appended claims for purposes of description and are not
intended to
indicate or imply relative importance or significance.
Conveyors
[0050] FIG. 1 shows a conveyor oven 20 having a conveyor 22 which runs through
a heated
tunnel 24 of the oven. The conveyor 22 has a width generally corresponding to
the width of
the heated tunnel 24 and is designed to travel in direction A from left oven
end 26 toward
right oven end 28 or, alternatively in direction B, from right oven end 28
toward left oven
end 26. Thus, oven ends 26 and 28 may serve respectively as the inlet and
outlet of an oven
with a rightwardly moving conveyor or as the outlet and inlet of an oven with
a leftwardly
moving conveyor.
[0051] The support, tracking and drive of conveyor 22 are achieved using
conventional
techniques such as those described in U.S. Patent Nos. 5,277,105 and 6,481,433
and
6,655,373, the contents of which are incorporated herein by reference insofar
as they relate
to conveyor support, tracking, and drive systems and related methods. In the
illustrated
embodiment, a chain link drive is housed within compartment 30 at the left end
26 of the
oven. Thus, a food product, such as a raw pizza 32R, may be placed on the
conveyor 22 of
CA 02783217 2012-06-29
the ingoing left oven end 26 and removed from the conveyor 22 as fully baked
pizza 32C
(see FIG. 5C) at the outgoing right oven end 28. The speed at which the
conveyor 22
moves is coordinated with the temperature in the heated tunnel 24 so that the
emerging fully
cooked pizza 32C is properly L4ned.
[0052] Normally only one conveyor is used, as shown. However, certain
specialized
applications may make two or more conveyors a preferable design. For example,
a first
conveyor may begin at left oven end 26 and travel at one speed to the center
or other
location of the oven 20, while a second conveyor beginning at such a location
and ending at
the right oven end 28 may travel at a different speed. Alternatively,
conveyors that are split
longitudinally may be used, so that one conveyor carries a product in
direction A while the
other conveyor carries a product in direction B, or so that two side-by-side
conveyors carry
product in parallel paths and in the same direction (A or B) through the oven
20. This
enables one product to travel on the conveyor at one speed to bake one kind of
product and
the other conveyor to travel on the other conveyor at a different speed to
bake another kind
of product. In addition, three or more side-by-side conveyors can carry
product in parallel
paths through the oven 20.
Access
[0053] With reference to FIG. 1, a hinged door 34 is provided on the front of
the oven 20,
with a heat resistant glass panel 36 and a handle 35 so that a person
operating the oven can
view food product as it travels through the oven 20. A stainless steel metal
frame surrounds
the oven opening and provides a support for a gasket of suitable material (not
shown), so
that when the door 34 is in its closed position, it fits against and
compresses the gasket to
retain heat in the oven 20, Also, the operator may open the door 34 by pulling
on handle 35
to place a different product on the conveyor 22 if less than a full bake cycle
is required to
produce a fully cooked product.
[0054] A hinged oven access panel 38 is also provided, open as shown in FIG.
2, to expose
inner workings and controls of the oven 20. As explained in more detail below,
in some
embodiments the hot air blowers and ducts, their associated components, and/or
the
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temperature sensors of the oven 20 can be located within the area revealed by
the opened
access panel 38.
Oven Controls
[0055] FIG. 3A shows a schematic illustration of the control system for the
oven 20. A
microprocessor-based controller 42 may include a central processing unit
("CPU") 650, one
or more displays 655, and a control interface 660. The CPU 650 can control a
plurality of
devices including one or more burners 60, 62 (including one or more blower
switches,
ignition switches and blowers, fuel valves, and flame sensing elements), one
or more fans
72, 74 (described in greater detail below), and one or more conveyors 22. The
CPU 650
may also receive input from a plurality of sensors including one or more
temperature
sensors 80, 82 and one or more photo sensors 79, 81 and/or 83, 85 (also
described in greater
detail below).
[0056] The oven controls, as shown in FIG. 3B, can include the controller 42
(such as a
Honeywell UDC 3300 controller) which may be programmed to control and monitor
the
baking process by pressing appropriate set-up and display buttons 44a-44h
while viewing
alphanumeric display 46, which will display process variables and setpoints
including oven
temperature, hot air blower speed, etc. A "heat on" indicator can be
illuminated when a
minimum threshold heat output is generated by the oven 20 under control of the
controller
42. The present temperature and/or the programmed setpoint temperature may be
displayed. By simultaneously pressing selected keys in some embodiments, the
value of the
heat output with the heat on indicator in the "on" condition can be displayed.
Also, the
controller 42 can be configured to enable a user to cycle through actual
temperature display
indicators to reveal the actual temperatures, setpoint temperature, and the
heat on condition.
In the illustrated embodiment, the speed and direction of the conveyor 22 can
be set using
buttons 48a, 48b, 50a and 50b and their associated displays 48c and 50c.
[0057] In some embodiments, the output display 46 can be automatically locked
in a default
display when a service person or operator places the controller 42 in a
service mode by
pressing appropriate key(s). Also, a failsafe condition can occur when any one
of various
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tests fail, at which time a signal display (e.g., one or more flashing
indicators) can be
displayed, such as a signal display flashing alternately with a temperature
display., For
example, if the oven 20 has not reached 200 F within 15 minutes after an
initial power-up
of the oven 20, a message can be Bashed on the display panel 46 indicating
that controls
need to be reset (e.g., power-cycled). As another example, if a temperature
sensor fails to
operate properly, the display 46 can flash "open". Also, the display 46 can
provide one or
more prompts for servicing the oven 20. Each additional press of a service
tool key can
advance so that a service person can continually sequence through service
prompts of a
service mode. The service mode can be exited, for example, by either pressing
an
appropriate key or by pressing no key for a set period of time (e.g., sixty
seconds). In either
case, the system can be automatically returned to a normal state.
[00581 In the illustrated embodiment, a setpoint lock key 42d can
automatically flash the
temperature that has been selected for an operation of the oven 20. In some
embodiments,
this setpoint temperature can be increased or decreased by pressing either
increment or
decrement keys 42f, 42g. Also, in some embodiments the degrees ( For C)
used for the
prompts can be changed by pressing either the increment or decrement keys 42f,
42g.
While at a degrees F or C prompt, a selection of "F" or "C" can
automatically change the
units of all the display 46 to F or C. While a default display prompt is
being displayed,
an indicator can flash to indicate which display is chosen as the default
display, which can
be changed, for example, by pressing either the increment or decrement keys
42f, 42g.
100591 In some embodiments, the oven 20 is operated by: (1) turning a blower
control 52 to
an "ON" position to start a blower (described in greater detail below), (2)
setting the
temperature to a desired level using the controller 42 as described above, (3)
turning a heat
control 54 to an "ON" position to supply gas and to trigger ignition of the
oven burner(s)
(described in greater detail below), (4) turning a conveyor control 56 to an
"ON" position to
drive the conveyor 22, and (5) after an appropriate pre-heat period, placing
food products on
the conveyor and beginning the baking process.
Tunnel Segments
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13
[0060] Heat delivery systems for supplying heat to the tunnel 24 are described
in U.S.
Patent Nos. 5,277,105, 6,481,433 and 6,655,373, the disclosures of which are
incorporated
herein by reference insofar as they relate to heat delivery systems for ovens.
These systems
typically include a heat source in the form of a single gas-fired burner (or
other heat source)
for heating a plenum. For example, the burner can be located at the front of
the oven for
heating a plenum located at the back of the oven. Blowers are typically
provided to move
heat in the plenum through passageways to metal fingers that open into the
oven at .
appropriate spacings from the conveyor belt to deliver streams of hot air onto
food products
present on the conveyor, as discussed earlier. The heat source is cycled on
and off as
necessary by a controller responding to signals from temperature sensors
(e.g.,
thennocouples) positioned, for example, at the inlet and outlet ends of the
oven tunnel.
[0061] In some embodiments of the present invention, uniform heating from one
end of the
tunnel 24 to the other is achieved by apportioning the tunnel 24 into two or
more segments
and by providing independent temperature sensing and independent delivery of
heated air to
each segment. This is shown diagrammatically in FIG. 4, where the oven 20 has
a pair of
burners 60 and 62 with respective heating flames 64 and 66 supplying heat to
respective
independent plenums 68 and 70 associated with segments 20A and 20B of the oven
20. The
heat in plenums 68 and 70 is blown into the two oven segments 20A, 20B by
separate
blower fans 72 and 74 through holes 75 and 77 in groupings of top fingers 76
and 78 (and
through holes in corresponding groupings of bottom fingers, not shown)
associated with the
respective oven segments 20A, 20B.
[0062] A number of different types of fans 72, 74 can be utilized for
supplying heated air
within the oven 20, and can be driven by any type of motor. As will be
described in greater
detail below, it is desirable in some embodiments to control the speed of
either or both fans
72, 74 based at least in part upon one or more temperatures sensed within the
oven 20, one
or more positions of food within, entering, or exiting the oven 20, and/or the
passage of one
or more predetermined periods of time. To provide control over fan speed based
upon any
of these factors, the fans 72, 74 can be driven by motors (not shown) coupled
to and
controlled by the controller 42. In some embodiments, the fans 72, 74 are
driven by
variable-speed motors coupled to and controlled by the controller 42. Power
can be
CA 02783217 2012-06-29
14
supplied to each variable-speed motor by, for example, respective inverters.
In some
embodiments, each inverter is a variable-speed inverter supplying power to the
motor at a
frequency that is adjustable to control the speed of the motor and, therefore,
the speed of the
fan 72, 74. An example of su_h an inverter is inverter Model No. MD60
manufactured by
Reliance Electric (Rockwell Automation, Inc.). By utilizing variable speed
motors supplied
by power through respective inverters as just described, a significant degree
of control over
fan speed and operation is available directly via the controller 42 connected
to other
components of the control system.
[00631 The temperatures in each of the oven segments 20A, 20B can be monitored
by
temperature sensors (e.g., thermocouples or other temperature sensing
elements) 80 and 82,
which are shown in FIG. 4 as being mounted near the inlet end 26 and the
outlet end 28 of
the oven 20. Either or both temperature sensors 80, 82 can be located in
respective plenums
68, 70 as shown in the figures. In some alternative embodiments, either or
both temperature
sensors 80, 82 are instead located within the chamber through which the
conveyor 22
moves. Either or both sensors 80, 82 can be positioned nearer the midpoints of
the
segments 20A, 20B or in other locations, if desired. In addition to or in
place of either or
both temperature sensors 80, 82, one or more position sensors 79, 81 and/or
83, 85 can be
located to detect the position of a pizza on the conveyor 22, and to thereby
control one or
more operations of the oven 20 as a result of such position detection
(described in greater
detail below). Furthermore, in those embodiments in which the oven 20 is
heated by one or
more gas burners, one or more gas output sensors (not shown) can be positioned
to detect
the amount of fuel supplied to the oven 20. This information can be provided
to the
controller 42 in order to control one or more operations of the oven 20, such
as to turn a
conveyor 22 and/or fan 72, 74 on or off, and/or to adjust the speed of the
conveyor 22
and/or fan 72, 74.
(0064] The operation of the oven proceeds as shown in FIGS. 5A-5C, which
includes a
diagrammatic representation of a pizza moving through the oven tunnel 24 below
graphs
showing the changing BTU output of the burners 60, 62 and the corresponding
blower
output as the pizza advances through the tunnel 24. Thus, a raw pizza 32R is
shown in FIG.
CA 02783217 2012-06-29
5C resting on the conveyor 22 before the pizza enters the oven tunnel 24. In
the illustrated
embodiment of FIG. 5C, the oven 20 has been heated to a desired temperature.
[00651 The oven 20 according Liu some embodiments of the present invention can
detect the
presence of a raw pizza 32R on the conveyor 22 by a position sensor 79, 81.
The position
sensor 79, 81 can take a number of different forms, and need not necessarily
comprise
components on opposite sides of the conveyor 22 as illustrated in FIG. 4. By
way of
example only, the position sensor 79, 81 can be an optical sensor positioned
to detect the
interruption of a beam of light (e.g., by a raw pizza 32R) extending across
the conveyor 22
at the entrance of the left tunnel segment 20A, an infrared detector
positioned to detect a
raw pizza 32R having a reduced temperature on the conveyor 22, a motion sensor
positioned to detect motion of a raw pizza 32R upon the conveyor 22, or any
other sensor
capable of detecting the presence of the raw pizza 32R on the conveyor 22. In
the
illustrated embodiment of FIG. 4, for example, the position sensor 79, 81
comprises a light
source 79 emitting a laser or other beam of light across the conveyor 22 to a
reflector 81,
which reflects the beam of light back to a photocell 81 (which may or may not
be associated
with the light source 79). Alternatively, the light source 79 and the
photocell 81 can be on
opposite sides of the conveyor 22, in which case an interruption in the beam
of light can still
be detected by the photocell 81.
[00661 In those embodiments of the present invention employing a position
sensor 79, 81 at
or adjacent the entrance of the left tunnel segment 20A as just described, the
position sensor
79, 81 can be coupled to the controller 42, and can send one or more signals
to the
controller 42 responsive to the detection of a raw pizza 32R (or lack thereof)
on the
conveyor 22. The controller 42 can be responsive to the position sensor 79, 81
by
increasing the BTU output of either or both burners 60, 62. In some
embodiments, the
controller 42 responds to the signal(s) from the position sensor 79, 81 by
increasing the
BTU output of the burner 60 of the left tunnel segment 20A, and can also
respond to the
signal(s) from the position sensor 79, 81 by increasing the speed of either or
both fans 72,
74. Either response can occur immediately or after a lag time, and can occur
relatively
abruptly or gradually.
CA 02783217 2012-06-29
16
[0067] For example, the controller 42 can gradually increase the speed of both
fans 72, 74
from a slow, relatively quiet standby level 71 to a full speed level 73,
thereby supplying
additional heat to both segments 20A and 20B of the tunnel (although an
increase supply of
heat can instead be provided to only one of the segments 20A, 20B in other
embodiments).
As another example, the controller 42 can respond to the signal(s) from the
position sensor
79, 81 by quickly increasing the BTU output of the burner 60 of the left
tunnel segment
20A, by gradually increasing the BTU output of the burner 60 as the raw pizza
32R enters
the left tunnel segment 20A, or by quickly or gradually increasing the BTU
output of the
burner 60 only after a set period of time pennitting either or both fans 72,
74 to increase in
speed. In these and other embodiments, the controller 42 can respond to the
signal(s) from
the position sensor 79, 81 by gradually increasing the BTU output of the
burner 62 of the
right tunnel segment 20, by gradually or quickly increasing the BTU output of
the burner 62
following a lag time (e.g., a predetermined period of time that can be
independent or
dependent upon the speed of the conveyor 22), or by changing the BTU output of
the burner
62 in any other manner.
[0068] If desired, the temperature sensor 80 can be used to detect the
presence of a raw
pizza 32R on the conveyor 22. For example, as the raw pizza 32R enters the
oven 20 and
approaches position 32(1), it draws heat causing sensor 80 (FIG. 4) to call
for the controller
42 to supply additional gas to the burner 60 and/or to increase the speed of
either or both
fans 72, 74. The controller 42 can respond to detection of the raw pizza 32R
by the
temperature sensor 80 in any of the manners described above with reference to
the position
sensor 79, 81. The position sensor 79, 81 and the temperature sensor 80 can be
connected
to the controller 42 in parallel, thereby enabling the controller 42 to change
the BTU output
of the burner 60 and/or the speed of either or both fans 72, 74 based upon
signals received
by the position sensor 79, 81 or the temperature sensor 80.
[0069] Until air in the plenum(s) 68, 70 has been sufficiently heated, the
above-described
fan control generates a reduced amount of heat loss and fan noise from the
oven tunnel 24
into the surrounding environment, and defines a load management setback of the
oven 20.
The establishment of a quiet and reduced airflow standby state of the fan(s)
72, 74 is an
advantage of the load management setback. Also, while the fans 72, 74 in the
illustrated
CA 02783217 2012-06-29
17
embodiment are operated in tandem, in alternate embodiments they could be
operated
independently of one another (e.g., so that the fan speeds are increased from
their slower
steady state level on an independent "as-needed" basis). Finally, it is noted
that the fans 72,
74 in the illustrated embodiment operate at about 2900 RPM at full speed and
at a level of
about 1400 RPM when in the standby mode. The full speed and standby speeds can
vary
depending at least in part upon design constraints of the oven 20, the food
being cooked,
etc. For example, the standby mode of either or both fans 72, 74 can be faster
or slower as
desired, such as a 2100 RPM standby speed for both fans 72, 74.
[0070] With continued reference to the illustrated embodiment of the present
invention
shown in FIGS. 5A-5C, as a pizza advances to the right to position 32(2), the
pizza is now
warmed. Therefore, less heat is drawn by the pizza, and the temperature in the
first tunnel
segment 20A rises. In some embodiments, this temperature rise is detected by
the
temperature sensor 80 of the first tunnel segment 20A, which can signal the
controller 42 to
reduce the supply of gas to the left burner 60, thereby producing a reduction
in BTU output
as shown in FIG. 5B. In these and other embodiments, the controller 42 can be
triggered to
reduce the supply of gas to the left burner 60 by a position sensor positioned
in or adjacent
the first tunnel segment 20A to detect when the pizza has advanced to a
location in the first
tunnel segment 20A. The position sensor can have any of the forms described
above with
reference to the position sensor 79, 81 at or adjacent the entrance to the
left tunnel segment
20A. The lowered BTU output level can continue for any part or all of the
remaining time
that the pizza is in the first tunnel segment 20A (e.g., all of such time as
shown in the
illustrated embodiment of FIG. 513).
[0071] Next, the pizza reaches the position 32(3) shown in FIG. 5C, and then
passes the
midpoint of the tunnel 24 between the two segments 20A, 20B. Since the pizza
has exited,
and there is therefore no further significant perturbation to the heating
environment in
segment 20A, the controller 42 can lower the gas supply (and therefore the BTU
output) of
the left burner 60 to a reduced steady state. This reduction can be triggered
by a threshold
temperature change detected by the temperature sensor 80 in the first tunnel
segment 20A
and/or by the temperature sensor 82 in the second tunnel segment 20B.
Alternatively or in
addition, this reduction can be triggered by one or more signals from a
position sensor
CA 02783217 2012-06-29
18
positioned to detect when the pizza has advanced to a location between the
first and second
tunnel segments 20A, 20B (or near such a location). The position sensor can
have any of
the forms described above with reference to the position sensor 79, 81 at or
adjacent the
entrance to the left tunnel se,-,went 20A.
[00721 With continued reference to FIGS. 5A-5C, the right burner 62 supplies
heat to the
second tunnel segment 20B. The sensor 82 corresponding to the second tunnel
segment
20B can initially detect a spillover of heat from the first tunnel segment 20A
(i.e., as the
pizza enters and is in the first part of the baking process in the first
tunnel segment 20A).
Upon detection of sufficient spillover heat (e.g., when the sensor 82 detects
that a threshold
temperature has been reached), the sensor 82 can trigger the controller 42 to
drop the initial
BTU output of the right burner 62. However, when the partially cooked pizza
approaches
the right tunnel segment 20B, the pizza draws heat from the second tunnel
segment
environment. This heat draw can also be detected by the sensor 82 of the
second tunnel
segment 20B, 'which can trigger the controller 42 to supply additional gas to
the burner 62
of the second tunnel segment 20B. As a result, the BTU output of the right
burner 62 can
increase as the pizza moves to and through positions 32(4), 32(5), and 32(6).
The reduction
and increase of right burner BTU output just described can also or instead be
triggered by
one or more signals from one or more position sensors positioned in or
adjacent the second
tunnel segment 20B to detect when the pizza has advanced to one or more
locations within
the oven 20. The position sensor(s) can have any of the forms described above
with
reference to the position sensor 79, 81 at or adjacent the entrance to the
left tunnel segment
20A.
[00731 In some embodiments, when the pizza leaves the position 32(6) and
begins exiting
the tunnel 24, the temperature sensor 82 of the second tunnel segment 20B can
detect a rise
in the tunnel temperature, and can trigger the controller 42 to reduce the
output of the right
burner 62 as shown in the BTU output graph of FIG. 5B. The resulting reduction
in
temperature in the second tunnel segment 20B can also be detected by the
temperature
sensor 80 of the first tunnel segment 20A due to heat spillover between the
two tunnel
segments 20A, 20B, and can trigger the controller 42 to increase the output of
the left
burner 60 to maintain the steady state temperature between the two oven
segments 20A,
CA 02783217 2012-06-29
19
20B. Alternatively, the controller 42 can automatically increase the output of
the left burner
60 when the output of the right burner 62 is reduced (or near in time to such
reduction of the
right burner 62). In some embodiments, the controller 42 can also respond by
returning the
speed of the fans 72, 74 to a standby state, This change in fan operation can
take place
relatively abruptly or gradually, and can take place immediately after a
threshold
temperature is detected by either or both sensors 80, 82 or after a
predetermined period of
time.
[0074] The increase of the left burner BTU output and the decrease in the
right burner BTU
output just described can also or instead be triggered by one or more signals
from a position
sensor positioned to detect when the pizza is exiting or has exited the right
tunnel segment
20B. For example, the oven 20 illustrated in FIG. 4 has a position sensor 83,
85
(comprising a light source 83 and a photocell 85) that is substantially the
same as the
position sensor 79, 81 at the entrance to the left tunnel segment 20A
described above. In
other embodiments, the position sensor 83, 85 can have any of the forms
described above
with reference to the position sensor 79, 81 at or adjacent the entrance to
the left tunnel
segment 20A.
[0075] The position sensor 83, 85 and the temperature sensor 82 can be
connected to the
controller 42 in parallel, thereby enabling the controller 42 to change the
BTU output of the
burner 62 and/or the speed of either or both fans 72, 74 based upon signals
received by the
position sensor 83, 85 or the temperature sensor 82.
[0076] The BTU output of either or both burners 60, 62 can be controlled by
the controller
42 in any manner desired. For example, the gas supply to either or both
burners 60, 62 can
be lowered or raised by the controller 42 relatively abruptly or gradually
upon detection of
threshold temperatures by either or both temperature sensors 80, 82, after a
set period of
time, and/or after sufficient movement of the pizza is detected by a position
sensor.
[0077] Accordingly, in some embodiments, the controller 42 can control either
or both fans
72, 74 based at least in part upon the temperature detected by a temperature
sensor 80, 82,
an amount of time elapsed following a change in power supply to a burner 60,
62, and/or the
CA 02783217 2012-06-29
detection of a position of pizza or other food on the conveyor 22 by a photo
sensor 79, 81,
83, 85. For example, in some embodiments the speed of either or both fans 72,
74 is
increased after air driven by the fan(s) 72, 74 has been sufficiently heated.
[00781 Similarly, in some embodiments the controller 42 can control the BTU
output of
either or both burners 60, 62 based at least in part upon the temperature
detected by a
temperature sensor 80, 82, an amount of time elapsed following a change in
speed of a fan
72, 74, and/or the detection of a position of pizza or other food on the
conveyor 22 by a
photo sensor 79, 81, 83, 85. For example, in some embodiments the BTU output
of either
or both burners 60, 62 is increased only after either or both fans 72, 74 are
brought up to a
threshold speed.
[0079) In some embodiments, the oven 20 can include one or more temperature
sensors 93,
95 (e.g., thermocouples) coupled to the controller 42 and positioned to detect
the BTU
output of eithei or both burners 60, 62. Using such an arrangement of
elements, a speed
change of the fans 72, 74 can be delayed for a desired period of time in order
to prevent
undue cycling of the fans 72, 74 as temperatures rise and fall within the
tunnel 24 and as the
BTU output of the burners 60, 62 rise and fall. In this regard, as the BTU
output detected
by either or both temperature sensors 93, 95 decreases below a threshold
level, power to
either or both fans 72, 74 can remain unchanged for a set period of time,
after which time
power to the fans 72, 74 can be reduced to a standby speed of the fans 72, 74.
[0080) In the illustrated embodiment, for example, a relay 91 coupled to the
temperature
sensors 93, 95, is also coupled to the controller 42, and cooperates with the
controller 42 to
reduce power to either or both fans 72, 74 in a manner as just described. In
this
embodiment, when the output of either burner 60, 62 falls below a threshold
value (e.g.,
60% of maximum output in some embodiments), the relay 91 and controller 42
enter into a
timed state. When the output of either burner 60, 62 remains below the
threshold value for
a set period of time (e.g., five minutes in some embodiments), either or both
burners 60, 62
are shut off. Either or both burners 60, 62 can be re-activated in some
embodiments by
detection of a sufficiently low threshold temperature by either of the tunnel
segment
temperature sensors 80, 82, by sufficient movement of a pizza detected by any
of the
CA 02783217 2012-06-29
21
position sensors described above, after a set period of time has passed, and
the like. Thus,
as the BTU output of either or both burners 60, 62 move above and below one or
more
threshold levels, the tendency of the fans 72, 74 to cycle (e.g., between high
and low speed
levels, and in some cases between on and off states) is reduced. Instead, the
fans 72, 74 can
remain at a full speed level until a lowered BTU level is established for at
least the set
period of time, such as for five minutes in the illustrated embodiment.
[0081] Under some operating conditions, the BTU output of the burners 60, 62
in some
embodiments can be reduced to a relatively low level (e.g., as low as a 5:1
air to gas ratio, in
some cases). A description of burner features enabling this low BTU burner
output is
provided below. Relatively low (and relatively high) burner BTU output can
generate
problems associated with poor combustion. For example, relatively low burner
BTU output
can generate incomplete combustion and flame lift-off. To address these
issues, the
controller 42 in some embodiments of the present invention is adapted to turn
gas to either
or both burners 60, 62 completely off in the event that either or both
temperature sensors 80,
82 detect that a low threshold temperature has been reached.
100821 In some of these embodiments, when either temperature sensor 80, 82
detects that a
sufficiently low temperature has been reached, the controller 42 responds by
turning off gas
to the burner 60, 62 associated with that temperature sensor 80, 82 (either
immediately or if
a higher temperature is not detected after a set period of time). The supply
of gas to the
burner 60, 62 can be restored after a period of time and/or after the
temperature sensor 80,
82 detects a temperature below a lower predetermined threshold temperature. In
this
manner, the burner 60, 62 can be cycled in order to avoid operating the burner
60, 62 at a
very low BTU output, As will be described in greater detail below, in some
embodiments
two or more burners 60, 62 will always be on or off together. In such cases,
the controller
42 can respond to a low threshold temperature by turning off the supply of gas
to both
burners 60, 62, and can restore the supply of gas to both burners 60, 62 after
a period of
time and/or after the temperature sensor 80, 82 detects that a lower threshold
temperature
has been reached.
CA 02783217 2012-06-29
22
[0083] Similarly, in some embodiments, when either temperature sensor 80, 82
detects that
a sufficiently high temperature has been reached, the controller 42 responds
by turning off
gas to the burner 60, 62 associated with that temperature sensor 80, 82
(either immediately
or if a lower temperature -not detected after a set period of time). The
supply of gas to the
burner 60, 62 can be restored after a period of time and/or after the
temperature sensor 80,
82 detects a temperature below the low threshold temperature or a sufficient
drop in
temperature. In this manner, the burner 60, 62 can be cycled in order to avoid
operating the
burner 60, 62 at a very high BTU output. As will be described in greater
detail below, in
some embodiments two or more burners 60, 62 will always be on or off together.
In such
cases, the controller 42 can respond to a high threshold temperature by
turning off the
supply of gas to both burners 60, 62, and can restore the supply of gas to
both burners 60,
62 after a period of time and/or after the temperature sensor 80, 82 detects a
temperature
below the low threshold temperature or an otherwise sufficient drop in
temperature.
[0084] Although only two tunnel segments 20A, 20B are used in the illustrated
embodiment, more than two tunnel segments can be used in other embodiments,
each such
alternative embodiment having one or more tunnel segments with any combination
of the
elements and features described above with reference to the illustrated
embodiment. Also,
as described above, the illustrated embodiment uses separate burners 60, 62
for each tunnel
segment 20A, 20B. In other embodiments, it is possible to achieve the desired
segment-
specific heating using a single burner and conventional structure and devices
to direct heat
to each segment independently in response to signals from temperature sensors
associated
with each of the segments. Finally, although gas burner(s) are preferred,
other heating
elements and devices can instead or also be used (e.g., one or more electric
heating
elements). As used herein and in the appended claims, the term "heating
elements" refers to
gas burners, electric heating elements, microwave generating devices, and all
alternative
heating elements and devices.
Energy Management
[0085] In some embodiments, it may be desirable to operate the oven 20 in one
or more
energy saving modes. Components of the oven 20 that can be controlled to
provide energy
CA 02783217 2012-06-29
23
savings may include either or both burners 60 and 62, either or both fans 72
and 74, and/or
the conveyor 22.
[0086] Saving energy wit,. he burners 60 and 62 maybe achieved by lowering the
temperature threshold in one or both of the plenums 68 and 70 that the burners
60 and 62
heat. This lower threshold can cause one or both of the burners 60 and 62 to
be on less
often, or to operate at a lower output, resulting in energy savings.
Additionally, one or both
of the burners 60 and 62 may be turned off completely.
[0087] Saving energy with the fans 72 and 74 may be achieved by reducing the
speed or
RPMs of one or both of the fans 72 and 74 which can require less power and,
therefore,
save energy. Additionally, one or both of the fans 72 and 74 maybe turned off
completely.
[0088] Saving energy with the conveyor 22 may be achieved by slowing down or
turning
off the conveyor 22.
[0089] While it may be possible to set the plenum temperature, fan speed, and
conveyor
speed to any number of values between a minimum and a maximum, it may be more
practical to choose one or more settings in the range between each minimum and
maximum.
[0090] Energy management strategies may include controlling any one or more of
the
burners 60, 62, fans 72, 74, and conveyor 22 of the oven 20 individually or in
combination
and/or controlling such components in the different segments of the oven 20
individually or
in combination.
[0091] Energy management events which cause one or more energy management
strategies
described herein to execute may be triggered by one or more actions, alone or
in
combination, including a predetermined amount of elapsed time, feedback from
one or more
temperature sensors, feedback from one or more position sensors, feedback from
one or
more motion detectors, and the like.
CA 02783217 2012-06-29
24
[00921 Fig. 12 illustrates a process for an energy management mode that can be
utilized for
a conveyor oven, such as the pizza oven 20 of Fig. 4. At step 300, the
controller 42 can
check for the presence of a pizza on conveyor 22. A pizza can be detected in
any of the
manners described herein, such as by one or more optical sensors 79 and 81. If
a pizza is
detected, a timer can be reset, either or both of the fans 72 and 74 can be
set to a higher
speed, and/or either or both of the burners 60, 62 can be set to a higher
level to raise the
temperature in one or both of the plenums 68, 70 to a higher level (steps 305,
310, and 315).
If no pizza is detected by the sensors 79 and 81 (step 300), the controller 42
can check a
timer to determine the period of time since the last pizza was put on the
conveyor 22 (step
320). If the timer is less than a predetermined threshold, the operation of
the oven 20 can
remain unchanged and the controller 42 can continue to check for the presence
of a pizza
(step 300). If the timer exceeds the predetermined threshold, the controller
42 can go into
an energy saving mode. In this energy saving mode, either or both fans 72 and
74 can be set
to a low speed and the temperature can be set to a low value (steps 325 and
330). The
controller 42 can then continue to check for the presence of a pizza on the
conveyor 22 (step
300). The controller 42 can remain in this energy saving mode until a pizza is
detected on
the conveyor 22 at step 300.
100931 Fig. 13 illustrates another embodiment of a process for an energy
management mode
that can be utilized for a conveyor oven, such as the pizza oven 20 of Fig. 4.
At step 335,
the controller 42 can check for the presence of a pizza on conveyor 22. A
pizza can be
detected in any of the manners described herein, such as by one or more
optical sensors 79
and 81. If a pizza is detected, a timer can be reset, either or both of the
fans 72 and 74 can
be set to a higher speed, and/or either or both of the burners 60, 62 can be
set to a higher
level to raise the temperature in one or both of the plenums 68, 70 to a
higher level (steps
340, 345, and 350). Since, as will be explained later, the oven temperature
can be relatively
low (e.g., if the oven has been in an energy management mode), it may be
necessary to wait
until the temperatures in the plenums 68 and 70 reach levels that will result
in temperatures
satisfactory for baking when the pizza arrives in the respective plenums
before allowing the
pizza on conveyor 22 to enter the oven 20. Therefore, at step 355, the
controller 42 can wait
until the temperatures of the oven 20 reach their thresholds.
CA 02783217 2012-06-29
[0094] Once the temperatures of the oven 20 reach their thresholds, the
conveyor 22 can
start (step 360) and the pizza can enter the oven 20 and bake. If no pizza is
detected by the
sensors 79 and 81 (step 335), the controller 42 can check a timer to determine
the period of
time since the last pizza was put on the conveyor 22 (step 365). If the timer
is less than a
predetermined threshold, the operation of the oven 20 can remain unchanged and
the
controller 42 can continue to check for the presence of a pizza (step 335). If
the timer
exceeds the predetermined threshold, the controller 42 can enter an energy
saving mode. In
this energy saving mode, either or both fans 72 and 74 can be set to a low
speed (step 370),
the burner 62 for either or both plenums 68, 70 can be turned off (e.g., the
back plenum 70
can be turned off as indicated at step 375), and the temperature in the first
plenum 68 can be
set to a lower level (step 380). The conveyor 22 can also be turned off (step
385). The
controller 42 can then continue to check for the presence of a pizza on the
conveyor 22 (step
335). The controller 42 can remain in this energy saving mode until a pizza is
detected on
the conveyor 22 at step 335.
[0095] Fig. 14 illustrates another embodiment of a process for an energy
management mode
that can be utilized for a conveyor oven, such as the pizza oven 20 of Fig. 4.
At step 400,
the controller 42 can check for the presence of a pizza on conveyor 22. A
pizza can be
detected in any of the manners described herein, such as by one or more
optical sensors 79
and 81. If a pizza is detected, a timer can be reset, either or both of the
fans 72 and 74 can
be set to a higher speed, and/or either or both of the burners 60, 62 can be
set to a higher
level to raise the temperature in one or both of the plenums 68, 70 to a
higher level (steps
405, 410, and 415). Since, as will be explained later, the oven temperature
can be relatively
low (e.g., if the oven has been in an energy management mode), it may be
necessary to wait
until the temperatures in the plenums 68 and 70 reach levels that will result
in temperatures
satisfactory for baking when the pizza arrives in the respective plenums
before allowing the
pizza on conveyor 22 to enter the oven 20. Therefore, at step 420, the
controller 42 can wait
until the temperatures of the oven 20 reach their thresholds.
[0096] Once the temperatures of the oven 20 reach their thresholds, the
conveyor 22 can
start (step 425) and the pizza can enter the oven 20 and bake. If no pizza is
detected by the
sensors 79 and 81 (step 400), the controller 42 can check a timer to determine
the period of
CA 02783217 2012-06-29
26
time since the last pizza was put on the conveyor 22 (step 420). If the timer
is less than a
predetermined threshold, the operation of the oven 20 can remain unchanged and
the
controller 42 can continue to check for the presence of a pizza (step 400). If
the timer
exceeds the predetermined threshold, the controller 42 can go into an energy
saving mode.
In this energy saving mode, either or both fans 72 and 74 can be turned off
(step 435), either
or both burners 60 and 62 can be turned off (step 440), and the conveyor 22
can be turned
off (step 445). The controller 42 can then continue to check for the presence
of a pizza on
the conveyor 22 (step 400). The controller 42 can remain in this energy saving
mode until a
pizza is detected on the conveyor 22 at step 400.
[0097] Fig. 15 illustrates another embodiment of a process for an energy
management mode
that can be utilized for a conveyor oven, such as the pizza oven 20 of Fig. 4.
The process
illustrated in Fig. 15 combines much of the processes illustrated in Figs. 12
and 13. At step
450, the controller 42 can check for the presence of a pizza on conveyor 22. A
pizza can be
detected in any of the manners described herein, such as by one or more
optical sensors 79
and 81. If a pizza is detected, a timer can be reset, either or both fans 72
and 74 can be set
to a high speed, and the temperature can be set to a high level (steps 455,
460, and 465). If
no pizza is detected by the sensors 79 and 81 (step 450), the controller 42
can check a timer
to determine the period of time since the last pizza was put on the conveyor
22 (step 470).
If the timer is less than a first predetermined threshold, the operation of
the oven 20 can
remain unchanged and the controller 42 can continue to check for the presence
of a pizza
(step 450). If the timer exceeds the first predetermined threshold, the
controller 42 can
check the timer to determine if it exceeds a second predetermined threshold
(step 475). The
second predetermined threshold is a period of time that is longer than the
first
predetermined threshold. If the timer does not exceed the second predetermined
threshold,
the controller 42 can enter a first energy saving mode.
[0098] In this first energy saving mode, either or both fans 72 and 74 can be
set to a low
speed and the temperature can be set to a low value (steps 480 and 485). The
controller 42
can then continue to check for the presence of a pizza on the conveyor 22
(step 450). The
controller 42 can remain in this first energy saving mode until a pizza is
detected on the
conveyor 22 at step 450 or until the threshold period of time since the last
pizza was
CA 02783217 2012-06-29
27
detected on the conveyor 22 (e.g., until the second predetermined threshold of
the timer is
exceeded). If, at step 475, the timer exceeds the second predetermined
threshold, the
controller 42 can enter a second energy saving mode.
[00991 In the second energy saving mode, either or both burners 60, 62 can be
turned off
(e.g., the burner 62 for the back plenum 70 can be turned off as indicated at
step 490), and
the conveyor 22 can be turned off (step 495). The controller 42 can then
continue to check
for the presence of a pizza on the conveyor 22 (step 500). The controller 42
can remain in
this second energy saving mode until a pizza is detected on the conveyor 22 at
step 500. If
a pizza is detected at step 500, the timer can be reset, either or both fans
72 and 74 can be
set to a high speed, and the temperature can be set to a high level (steps
505, 510, and 515).
Since, as will be explained later, the oven temperature can be relatively low
(e.g., if the
oven has been in an energy management mode), it may be necessary to wait until
the
temperatures in the plenums 68 and 70 reach levels that will result in
temperatures
satisfactory for baking when the pizza arrives in the respective plenums
before allowing the
pizza on conveyor 22 to enter the oven 20. Therefore, at step 520, the
controller 42 can wait
until the temperature(s) of the oven 20 reach their threshold(s). Once the
temperatures of
the oven 20 reach their thresholds, the conveyor 22 can start (step 525) and
the pizza can
enter the oven 20 and bake. The controller 42 can then exit the energy saving
modes and
continue checking for pizzas at step 450.
[001001 Fig. 16 illustrates another embodiment of a process for an energy
management
mode that can be utilized for a conveyor oven, such as the pizza oven 20 of
Fig. 4. The
process illustrated in Fig. 16 combines much of the processes illustrated in
Figs. 12, 13, and
14. At step 550, the controller 42 can check for the presence of a pizza on
conveyor 22. A
pizza can be detected in any of the manners described herein, such as by one
or more optical
sensors 79 and 81. If a pizza is detected, a timer can be reset, either or
both fans 72 and 74
can be set to a high speed, and the temperature can be set to a high level
(steps 555, 560,
and 565). If no pizza is detected by the sensors 79 and 81 (step 550), the
controller 42 can
check a timer to determine the period of time since the last pizza was put on
the conveyor
22 (step 570). If the timer is less than a first predetermined threshold, the
operation of the
oven 20 can remain unchanged and the controller 42 can continue to check for
the presence
CA 02783217 2012-06-29
28
of a pizza (step 550). If the timer exceeds the first predetermined threshold,
the controller
42 can check the timer to determine if it exceeds a second predetermined
threshold (step
575). The second predetermined threshold is a period of time that is longer
than the first
predetermined threshold. If the timer does not exceed the second predetermined
threshold,
the controller 42 can enter a first energy saving mode.
[00101] In the first energy saving mode, either or both fans 72 and 74 can be
set to a low
speed, and the temperature can be set to a low value (steps 580 and 585). The
controller 42
can then continue to check for the presence of a pizza on the conveyor 22
(step 550). The
controller 42 can remain in this first energy saving mode until a pizza is
detected on the
conveyor 22 at step 550 or until the threshold period of time since the last
pizza has been
detected on the conveyor 22 (e.g., until the second predetermined threshold of
the timer is
exceeded). If, at step 575, the timer exceeds the second predetermined
threshold, the
controller 42 can enter a second energy saving mode.
[00102] In the second energy saving mode, either or both burners 60, 62 can be
turned
off (e.g., the burner 62 for the back plenum 70, can be turned off as
indicated at step 590),
and the conveyor 22 can be turned off (step 595). The controller 42 can then
continue to
check for the presence of a pizza on the conveyor 22 (step 600). If a pizza is
detected at
step 600, the timer can be reset to zero, either or both fans 72 and 74 can be
set to a high
speed, and the temperature can be set to a high level (steps 605, 610, and
615). Since, as
will be explained later, the oven temperature can be relatively low (e.g., if
the oven has been
in an energy management mode), it may be necessary to wait until the
temperatures in the
plenums 68 and 70 reach levels that will result in temperatures satisfactory
for baking when
the pizza arrives in the respective plenums before allowing the pizza on
conveyor 22 to
enter the oven 20. Therefore, at step 620, the controller 42 can wait until
the temperature(s)
of the oven 20 reach their threshold(s). Once the temperatures of the oven 20
reach their
thresholds, the conveyor 22 can start (step 625) and the pizza can enter the
oven 20 and
bake. The controller 42 can then exit the energy saving modes and continue
checking for
pizzas at step 550.
CA 02783217 2012-06-29
29
[00103] If no pizza is detected by the sensors 79 and 81 (step 600), the
controller 42 can
check a timer to determine the period of time since the last pizza was placed
on the
conveyor 22 (step 630). If the timer is less than a third predetermined
threshold, the
operation of the oven 20 can remain in the second energy saving mode, and the
controller
42 can continue to check for the presence of a pizza (step 600). The third
predetermined
threshold is a period of time that is longer than the second predetermined
threshold. If the
timer exceeds the third predetermined threshold, the controller 42 can enter a
third energy
saving mode. In this third energy saving mode either or both fans 72 and 74
can be turned
off (step 635) and the first burner 60 can be turned off (step 640). The
controller 42 can
then continue to check for the presence of a pizza on the conveyor 22 (step
600). The oven
20 may remain in the third energy savings mode until a pizza is detected at
step 600. Once
a pizza is detected at step 600, processing continues at step 605 as
previously described.
[00104] Embodiments of three energy savings modes have been illustrated along
with
two combinations of the illustrated energy savings modes. Further embodiments
can
include, for example, combining the embodiments of Figs. 12 and 14 or Figs. 13
and 14.
Further, other methods of controlling the components of the conveyor oven can
be utilized
to create additional energy saving modes and combinations thereof.
[00105] As one skilled in the art will understand, numerous strategies and
combinations
of strategies exist for implementing energy management for an oven 20.
Considerations in
deciding which strategies to implement include the time it will take to be
ready for baking
after entering an energy saving mode and the amount of energy required to
reach baking
temperature following an energy saving mode. As such it can be desirable to
provide
multiple energy management strategies and allow users to choose the strategy
or
combination of strategies that best meets their needs.
[00106] In some embodiments, one or more remote input devices can provide an
indication to the controller 42 that food product (e.g., a pizza) needs to be
baked. Such
remote input devices can change the operational state of the oven 20, such as
by providing
trigger mechanisms (other than those described elsewhere herein) to prepare
the oven for
cooking. Remote input devices can include one or more push buttons, switches,
knobs,
CA 02783217 2012-06-29
keypads, operator interfaces, cash registers, or other user manipulatable
devices, one or
more sensors (e.g., pressure sensors, limit switches, optical sensors), a
computer, and the
like. The remote input device can communicate with the controller 42 in any
suitable
manner, including a bard-wired connection, a wireless connection, an internet
connection,
and any combination of such connections.
[00107] Fig. 24 illustrates an exemplary layout of a kitchen 1000 for cooking
and serving
pizzas. A counter 1005 can include one or more cash registers 1010 for taking
customer
orders. In addition to the conveyor oven 20, the kitchen 1000 can include a
refrigerator
1015, a preparation table 1020, a final preparation table 1030, and/or any
number of other
food preparation and cooking stations and equipment. Other examples of such
cooking
stations and equipment include walk-in coolers, sinks, racks, food processing
equipment
(e.g., mixers, grills, and the like), and the like. One or more remote devices
can be
associated with any of such cooking stations or equipment, and can provide
indication(s)
that food product needs to be prepared by the conveyor oven 20.
[00108] For example, in some embodiments, a switch or sensor of the
refrigerator 1015
can detect when the door of the refrigerator 1015 has been opened, and can
communicate
with the controller 42 via link 1040. As another example, in some embodiments,
a switch
or sensor of the preparation table 1020 can detect that food product is being
made (e.g., by
detecting the weight of food product placed upon the preparation table,
optically detecting
the presence of such food product, and the like), and can communicate with the
controller
via link 1045. As another example, in some embodiments, one or more cash
registers 1010
can inform the controller 42 via links 1050 and 1055 when a customer has
ordered a pizza.
As yet another example, the conveyor oven 20 can be provided with one or more
proximity
sensors adapted to detect the presence of a cooking element (e.g., a cooking
pan, tray,
container, and the like) within a range of distance from such sensors, and can
communicate
with the controller via a link. In such cases, the sensor can be an RFID
sensor, an LED
sensor, and the like, wherein the cooking element is adapted to be recognized
by the sensor,
such as by being provided with an antenna on or embedded within the cooking
element.
Other types of remote devices can be used in place of or in addition to those
just described
to inform the controller 42 that food product (e.g., one or more pizzas) needs
to be cooked,
CA 02783217 2012-06-29
31
thereby enabling the controller 42 to change the operational state of the oven
20
accordingly.
[00109] In some ernluvuiments, the controller 42 receives an indication from a
remote
device that a food product needs to be cooked (e.g., that a pizza ordered by a
customer at a
cash register will need to be cooked). The controller 42 can immediately exit
any energy
savings mode it is in and enter an operating mode (e.g., a baking mode) where
the conveyor
22 is turned on. In some embodiments, the speed of one or more fans 72, 74 can
be
increased and/or the heat output of one or more heating elements 60, 62 can be
increased in
the operating mode of the oven 20. Also, in other embodiments, the controller
42 may keep
the oven 20 in an energy saving mode for a period of time before entering the
operating
mode. The period of time the controller 42 keeps the oven 20 in the energy
saving mode
can be determined based at least in part upon the temperature of the oven 20
and/or a length
of time until baking is to begin.
1001101 For example, after receiving an indication from a remote device that
food
product needs to be cooked by the oven 20, the controller 42 can detect a
temperature of the
oven 20 and can compare the temperature of the oven 20 to a desired cooking
temperature.
The controller 42 can then calculate the length of time (or use a look-up
table to determine
the length of time) the oven 20 needs to heat up from the present temperature
in the oven 20
to the desired cooking temperature. The controller 42 can also know the amount
of time
from when the controller 42 receives the indication from the remote device
until the food
product is actually ready to be cooked (e.g., the preparation time). If the
time needed to
heat the oven 20 to the cooking temperature is less than the preparation time,
the oven 20
would reach the desired cooking temperature before the food product is ready
to be cooked
if the oven began heating up immediately upon receiving the indication from
the remote
device. Therefore, the controller 42 can delay heating the oven 20, such as
until the
remaining preparation time equals the amount of time needed to heat the oven
20 to the
desired cooking temperature.
[001111 In some embodiments, after receiving an indication from a remote
device that
food product needs to be cooked by the oven 20, the controller 42 can delay
heating the
CA 02783217 2012-06-29
32
oven 20 based at least in part upon a known time by which the food product
must be
delivered or a desired cooking completion time. The time to delivery can be
based on a
time of day (e.g., shorter during lunch and longer during dinner) or a
variable time (e.g., the
length of time until a dGiivery person will be available to deliver the food
product). The
cooking completion time can be based upon an anticipated dining rush or other
event. The
controller 42 can know the length of time the oven 20 needs to reach the
baking temperature
based at least in part upon the present temperature of the oven 20 as
discussed above. The
controller 42 can also know the total cooking time of the food product and the
length of
time needed after the food product is cooked and before the food product is
ready for
serving or delivery (final preparation time). For example, the controller 42
receives an
indication from a remote device that a pizza needs to be cooked. The
controller 42 knows
that the total baking time combined with the final preparation time is a
certain length of
time. If a delivery person will not be available to deliver the pizza until
some time later, the
controller 42 can determine when to heat the oven 20 based on when the
delivery person
will arrive minus the baking and final preparation time, and minus the time to
heat the oven
20 to the baking temperature. In this manner, the pizza can be hot and fresh
when the
delivery person is ready to begin his or her delivery run.
[00112] After a cooking process is complete, the controller 42 can
automatically cause
the oven 20 to enter or return to an energy saving mode. This process can be
delayed for a
predetermined period of time in order to prevent unnecessary cycling of the
oven 20, can be
overridden based upon an indication of additional food product to be cooked
(e.g., an
indication from a remote device as described above), or can be overridden
based upon a
reduction in oven demand (e.g., when the rate of food product to be cooked
falls to a
predetermined threshold).
[001131 Figs. 25A and B illustrate exemplary time lines for the operations
described
above. The controller 42 (see FIG. 24) receives an indication from a remote
device that a
pizza needs to be cooked at 1100. The controller 42 can then determine when
the pizza will
be ready to be placed on the conveyor 22 to be cooked (1105). The controller
42 knows the
preparation time of the pizza (the difference between 1105 and 1100 in Fig.
25A), and can
determine when to exit an energy-savings mode and to enter a heating mode
(1110) by
CA 02783217 2012-06-29
33
subtracting the heating time from the preparation time to arrive at the baking
mode time
(1110). The pizza then finishes baking at 1115 and is ready for delivery,
following final
preparation at 1120.
[001141 Fig. 25B illustrates an exemplary time line for the operation of an
oven 20 when
the time to delivery 1120 is greater than the total time needed to prepare and
cook a pizza.
The controller receives (at 1100) an indication from a remote device that a
pizza needs to be
cooked. The controller 42 can know the delivery time 1120. The controller 42
can work
backward from the delivery time (1120) to determine the time to start heating
the oven
(1110) by subtracting the final preparation time (the difference between 1120
and 1115), the
baking time (the difference between 1115 and 1105), and the heating time (the
difference
between 1105 and 1110), wherein the heating time can be calculated based upon
the
difference between the temperature of the oven and the desired baking
temperature.
[001151 in some embodiments, the controller 42 can enter an energy saving mode
immediately at 1115, provided a remote device has not indicated that another
pizza needs to
be cooked. The controller 42 can also attempt to maximize the energy savings
by setting a
target temperature of the oven 20, during an energy saving mode, such that the
heating time
is equal to the difference between the time an indication that a pizza needs
to be cooked is
received from a remote device (1100) and the time baking is to begin (1105).
This target
temperature can add time (indicated by 1125) to the heating time.
[001161 As described above, the controller 42 can receive one or more
indications from a
remote device to change oven operation based upon an anticipated demand for
cooked food
product. For example, in some embodiments, the indication(s) can turn the oven
20 on, can
increase the heat output of one or more heating elements 60, 62, and/or can
increase the
speed of one or more fans 70, 72. Also or in addition, different portions of
the oven 20 can
be activated or de-activated in order to increase or decrease the cooking
capacity of the oven
20 based upon the anticipated demand for cooked food product. Information
reflecting the
anticipated demand for cooked food product can also be received from the
remote device(s),
and can include data representing a quantity of food product to be cooked
and/or a rate of
food orders received).
CA 02783217 2012-06-29
34
[001171 For example, an oven 20 can have two or more conveyors 22 for moving
food
product through the oven 20. The conveyors 22 can be stacked, can be side-by-
side, or can
have any other configuration described herein. For example, in a "split
conveyor" (in which
two adjacent conveyors 22 of the same or different width run in parallel), a
first conveyor
22 can be operated independently of a second conveyor 22, such as by moving
faster or
slower than the second conveyor, in a direction opposite the second conveyor,
and the like.
Feedback regarding either or both conveyors 22 (e.g., speed, temperature, and
the like) can
be provided to a controller 42 for display upon an operator interface and/or
for adjustment
of oven operation in any of the manners described herein. For example, the
remote device
can indicate to the controller 42 a quantity of pizzas that need to be cooked.
The controller
42 can then determine if the first conveyor can cook the quantity of pizzas
within a desired
time. If the first conveyor cannot meet the demand, the controller 42 can
cause the oven 20
to exit an energy saving mode (e.g., a mode in which the heating elements
and/or fans
associated with less than all conveyors are in an operating mode). As a
result, one or more
additional conveyors with associated heating elements and fans can be brought
up to
operating temperature only as the demand for pizzas requires. If the quantity
of pizzas
needing to be cooked approaches or exceeds the maximum capacity of the
conveyor(s)
currently in an operating mode, the controller 42 can put one or more other
conveyors into
an operating mode or a stand-by mode in which such other conveyor(s) are
heated to a level
above the energy savings mode but less than the baking temperature.
[001181 It should be noted that the various energy-saving modes described
herein do not
indicate or imply that the oven 20 is incapable of cooking food product while
in an energy
saving mode. In some embodiments, an oven 20 can still cook food product while
in one or
more energy savings modes. For example, one or more conveyors of a multiple-
conveyor
oven can enter an energy saving mode while still being able to cook food
product on one or
more other conveyors of the oven. As another example, a conveyor oven 20 in a
period of
low demand can operate with significantly less heat and/or fan output while
still cooking
food product, such as by slowing the conveyor 22 without significantly
lengthening cooking
time.
CA 02783217 2012-06-29
[00119] In some embodiments, the controller 42 can determine the amount of
time
necessary to heat the oven 20 to the desired cooking temperature and can use
the cooking
time, final preparation time, and the initial preparation time to calculate a
time when a pizza
will be ready. The controller 42 can then provide this time to a display to
inform an
operator of the length of time necessary to prepare and cook the pizza.
Contiguous Burners
[00120] Many different heat sources can be used to independently supply
heating to each
of the oven segments 20A, 20B, including a number of different gas burner
configurations.
By way of example only, FIG. 6 illustrates a single burner of a contiguous
multiple burner
configuration which has been found to be particularly useful. This burner 100
comprises a
housing (e.g., an outer tube 102 as shown in the illustrated embodiment)
attached to a
mounting plate 104 which closes off the proximal end of the outer tube 102.
The outer tube
102 can have any shape desired, and in some embodiments has a relatively
elongated shape
as shown in the illustrated embodiment.
[00121] A smaller diameter venturi tube 106 is located within the outer tube
102 and has
open distal and proximal ends 107, 112. The venturi tube 106 can be generally
centered
with its longitudinal axis along the longitudinal axis of the outer tube 102,
although non-
concentric relationships between the venturi tube 106 and the outer tube 102
can instead be
employed. In some embodiments, the venturi tube 106 is secured in place near
its distal end
107 by a venturi support 108 encircling the venturi tube 106 and secured
within the inside
diameter 109 of the outer tube 102. In some embodiments, a section 111 of the
distal end
107 of the venturi tube 106 extends beyond the venturi support 108.
[00122] A gas orifice 110 can be located in the mounting plate 104, and can be
spaced
from the proximal open end 112 of the venturi tube 106. Ia some embodiments
(see FIG.
6), the gas orifice 110 can be centered or substantially centered with respect
to the open
proximal end 112 of the venturi tube 106, although other non-centered
relationships
between the venturi tube 106 and the gas orifice 110 are possible. The open
proximal end
112 of the venturi tube 106 receives pressurized gas from the gas orifice 110,
and serves as
CA 02783217 2012-06-29
36
a primary air inlet to admit a flow of air 115 into the venturi tube 106. In
other
embodiments, air can enter the proximal end 112 of the venturi tube 106
through apertures
or gaps in the end of the venturi tube 106, through one or more conduits
coupled to the
venturi tube 106, or in any other manner. In some embodiments, powered air is
supplied to
that portion of the outer tube 102 below the venturi support 108. For example,
a powered
air supply can be coupled to the outer tube 102 in the illustrated embodiment
via a conduit
113 leading to the outer tube 102.
[001231 The venturi support 108 can have any shape adapted to support the
venturi tube
106 and/or to at least partially separate an interior portion of the outer
tube 102 from a bum
region 116 opposite the proximal end 112 of the venturi tube 106. In some
embodiments,
the venturi support 108 is substantially disc shaped (e.g., see FIG. 6A). The
venturi support
108 can have an opening 117 (e.g., a central circular opening 117 as shown in
FIG. 6A)
which fits about the circumference of the venturi tube 106. Also, one or more
apertures can
be defined within the venturi support 108, and in some cases can be defined
between the
venturi support 108 and the outer tube 102 and/or the venturi tube 106. For
example, in the
illustrated embodiment, the venturi support 108 has edges 119 and 121 that
partially define
open gaps 123 and 125 between the circumference of the venturi support 108 and
the inside
diameter 109 of the outer tube 102. These gaps 123, 125 can admit secondary
air to the
bum region 116 opposite the proximal end 112 of the venturi tube 106 in order
to help
support combustion as will be explained in greater detail below. In an
alternate
embodiment, one or more adjustable shutters (e.g., a rotatable overlapping
flap, wall, or
disk) can be provided to adjust the amount of secondary air admitted to the
bum region 116.
[00124) In some embodiments, the venturi tube 106 can have a flame retention
member
118 which can help prevent lift-off of the flame from the distal end 107 of
the venturi tube
106. As seen in FIG. 6B, in some embodiments the flame retention member 118
comprises
a ring 120 spaced from the inside diameter of the distal end 107 of the
venturi tube 106,
thereby defining an annular space 122 between the ring 120 and the inside
diameter of the
venturi tube 106. The ring 120 can be permanently or releasably retained in
place with
respect to the venturi tube 106 in a number of different manners, such as by
one or more
fingers, pins, clips, or other fasteners, by an apertured disc, and the like,
In the illustrated
CA 02783217 2012-06-29
37
embodiment, the ring 120 is retained in place by a corrugated member 128
located within
the annular space 122. The corrugated member 128 abuts the inside diameter of
venturi
tube 106 and the outside diameter of the ring 120, and can be permanently
attached to the
venturi tube 106 and'or the ring 120. Also, the corrugated member 128 can hold
the ring
120 in place with respect to the venturi tube 106 by friction (e.g., between
the corrugated
member 128 and the venturi tube 106 and/or between the corrugated member 128
and the
ring 120.
[001251 In some embodiments, a target 124 is positioned opposite (and can be
spaced
from) the distal end 107 of the venturi tube 106. This target 124 can be
retained in this
position with respect to the venturi tube 106 in any manner, including those
described above
with reference to the retention of the ring 120 within the venturi tube 106.
In the illustrated
embodiment, for example, the target 124 is held in place by arms 126 extending
from the
target 124 to the outer tube 102, although the arms 126 could instead extend
to the venturi
tube 106 or other adjacent structure of the burner 100. The arms 126 can be
permanently or
releasably attached to the outer tube 102 and/or to the target 124 in any
suitable manner,
such as by welding, brazing, or riveting, by one or more snap-fits or other
inter-engaging
element connections, by clips, clamps, screws, or other fasteners, and the
like. In the
illustrated embodiment, the arms 126 are attached to the outer tube 102 by
frictionally
engaging the inside diameter 109 of the outer tube 102.
[001261 The target 124 can have a convex shape, with an apex extending
generally
toward the distal end 107 of the venturi tube 106. This target 124 can act to
spread a
portion 135 of the flame 134 emitted from the distal end 107 of the venturi
tube 106,
facilitating mixing of gas escaping from the venturi tube 106 with primary air
and
secondary air being supplied to this region through the venturi tube 106 and
the gaps 123,
125, respectively. In other embodiments, the target 124 can be substantially
flat, can
present a concave surface to the distal end 107 of the venturi tube 106, can
have any other
shape suitable for spreading the flame 134 as described above, and can have an
apex
directed toward or away from the distal end 107 of the venturi tube 106.
CA 02783217 2012-06-29
38
[00127] With continued reference to FIG. 6, in some embodiments the outer tube
102 of
the burner 100 is coupled to a flame tube 130, such as by being received
within an end of
the flame tube 130. The flame tube 130 can include a number of air openings
132 in any
arrangement or pattern, thereby supplying further oxygen to the burning gas
supporting the
flame 134, which can extend into the flame tube 130 when the burner 100 is
turned on.
1001281 In some embodiments of the present invention, the oven 20 has at least
one pair
of contiguous burners 100 and 150 of the design illustrated in FIGS. 6-68. A
pair of such
burners 100, 150 is illustrated in FIGS. 7A and 7B. The outer tubes 102, 102'
of the
respective burners 100, 150 can be mounted to a common base plate 104, and can
each be
fitted with a target 124, 124' as described above. Powered air for combustion
can be
supplied to a venturi enclosure 152 (e.g., a venturi box having a rectangular
shape or any
other shape desired) by way of an inlet 154 connected to a source of powered
air, as
described in more detail below.
[001291 In FIG. 7B, the cover of the venturi enclosure 152 has been removed to
expose a
base 156 of the venturi enclosure 152. The venturi enclosure 152 can have a
respective base
for each burner 100, 150, or can have a common base 156 (such as that shown in
FIG. 7B).
The base 156 illustrated in FIG. 7B has a pair of openings 158 and 160
associated
respectively with each of the two burners 100, 150. Air supply tubes 162 and
164 can
extend from openings 158 and 160 to the outer surface of each respective outer
tube 102
and 102', with the distal edge of each air supply tube 162, 164 shaped to
follow and to
sealingly engage the contour of the outer tubes 102, 102'. Outer tubes 102 and
102' can
each have a respective inlet 166 and 168 in communication with the air supply
tubes 162,
164. Thus, powered air from a blower 155 (see FIG. 2) entering the venturi
enclosure 152
through the inlet 154 can pass through air supply tubes 162 and 164 and
through air inlets
166 and 168 in the outer tubes 102, 102' of the burners 100, 150. In the
illustrated
embodiment, this powered air enters the venturi tubes 106 of the burners 100,
150 through
the proximal ends 107 of the venturi tubes 106, and also passes through gaps
123 and 125 in
the venturi support disks 108.
CA 02783217 2012-06-29
39
[00130] Gas can be supplied to the burners 100, 150 at their proximal ends 112
in any
suitable manner, such as through a shared supply tube or through respective
supply tubes
170 and 172 as shown in FIGS. 7A and 7B. The supply tubes 170, 172 shown in
FIGS. 7A
and 7B have been cut away to facilitate viewing the rest of the burners 100,
150. The
supply tube(s) can be mounted to the burners 100, 150 in any manner, such as
by one or
more clamps, braces, or other fixtures, and can be mounted to one or more
mounting
flames, plates, or other structures adapted for this purpose. By way of
example only, the
supply tubes 170, 172 in the illustrated embodiment are mounted on brackets
174 and 176
attached to a common plate 178, which in turn is attached to the base plate
104 of the
burners 100, 150. Either or both gas supply tubes 170, 172 can have any type
of common
valve or respective valves in order to control the supply of gas to the
burners 100, 150. In
the illustrated embodiment, for example, a threaded valve pin 180, 182 on each
supply tube
170, 172 can be advanced and retracted for fine adjustment of gas supplied to
the burners
100, 150 through orifices (not shown) in the gas supply tubes 170, 172
adjacent the gas
orifices 110 (see FIG. 6). The present design makes it possible to use a
single main gas
valve with any number of contiguous burners, and in some embodiments to also
adjust each
burner 100, 150 independently of the others.
[00131] The distal ends of the outer tubes 102 and 102' in the illustrated
embodiment are
shown in FIG. 8 (in which the target 124' has been removed from the second
burner 102').
In this figure, the outer tubes 102, 102' are spot welded in place in a
support plate 184. In
other embodiments, the support plate 184 is not required, in which case a
common
mounting plate 104 (or respective mounting plates 104 coupled together in any
manner) can
secure the outer tubes 102, 102' with respect to one another. In those
embodiments in
which a support plate 184 is utilized, the support plate 184 can be attached
to the outer tubes
102, 102' in any manner, such as in any of the manners of attachment described
above with
reference to the attachment of the arms 126 to the outer tube 102. Also, in
some
embodiments, the outer tubes 102, 102' and the burners 100, 150 can be secured
in place
with respect to one another by a common support plate 184 (or by respective
support plates
coupled together in any manner) without this function being performed by one
or more
mounting plates 104 as described above.
CA 02783217 2012-06-29
[00132] With reference again to FIG. 8, one burner 150 is provided with an
igniter 186,
which produces a spark to ignite gas escaping from the distal end 107 of
venturi tube 106
(see FIG. 6). The flame produced crosses over to the other burner 150 by way
of a cross-
over structure which will discussed below. The burner 150 can be provided with
a flame
sensor 188 as a fail-safe measure to shut off the gas supply to both burners
100, 150 should
the flame produced in burner 150 fail to cross over to the adjacent contiguous
burner 100.
In some embodiments, each burner 100, 150 can be provided with a respective
flame sensor
188 that can trigger gas shut-off when no flame is detected from the
corresponding burner
100, 150 after a sufficient period of gas supply time has elapsed. Also, in
some
embodiments (e.g., where independent burners 100, 150 are used to deliver heat
to each of
the oven segments), each burner 100, 150 can have its own independent igniter
186.
[00133] In some embodiments of the present invention, the outer tubes 102 and
102' of
the burners 100, 150 are each provided with at least one aperture 200, 202
(see FIGS. 9A
and 9C) through which fluid communication is established between the burn
regions 116 of
the burners 100, 150. By such fluid communication, heat from a flame 134
ignited in one of
the burners 100, 150 can raise the temperature in the other burner 150, 100
sufficiently to
ignite the other burner 150, 100.
[00134] The aperture(s) 200, 202 in each of the outer tubes 102, 102' can be
rectangular,
round, oval, irregular, or can have any other shape desired. Also, the
apertures 200, 202 can
be open to or located a distance from the ends of the outer tubes 102, 102'
adjacent the bum
regions 116 (e.g., see FIGS. 6 and 9A), and can extend in a direction away
from the
respective venturi tubes 106 to locations past the targets 124, 124'. In the
illustrated
embodiment, for example, each of the outer tubes 102, 102' has a substantially
rectangular
aperture 200, 202 located a distance from the end of the respective outer tube
102, 102'
adjacent the region 116.
[00135] The apertures 200, 202 in the outer tubes 102, 102' can, in some
embodiments,
be joined by a conduit 212 extending between the apertures 200, 202. Such a
conduit 210
can help direct heat to an unlit burner 100, 150 to a lit burner 150, 100 in
order to light the
unlit burner 100, 150. The conduit 210 can have any shape desired, such as a
substantially
CA 02783217 2012-06-29
41
rectangular or round cross-sectional shape, an irregular shape, and the like.
The conduit 210
can be enclosed or partially enclosed, and in the illustrated embodiment of
FIGS. 9A-9D is
enclosed on all sides by top, bottom, front, and back plates 204, 206, 208,
and 210,
respectively. The plates 204, 206, 208, 210 or other elements used to define
the conduit 212
can be sealed to one another and to the outer tubes 102, 102', such as by
fluid-tight welds,
brazing, and the like, Such seals can protect the interior of the conduit 212
from the
surrounding environment.
[00136] Thus, when gas passing through a first burner 100 is ignited, the
flame produced
at the distal end 107 of the venturi tube 106 in the first burner 100 can
cross over through
the conduit 212 to the distal end 107 of the venturi tube 106' in the second
burner 150,
thereby igniting the contiguous second burner 150. In such embodiments, the
two burners
100, 150 are therefore either always on or always off together. Furthermore,
should the
flame 134 in the first burner 100 fail to cross over or be lost in the second
burner 150, the
sensor 188 (if employed) can signal the controller 42, which can respond by
cutting off gas
to both burners 100, 150. This arrangement thus makes it possible to avoid
situations in
which only one of two burners 100, 150 is lit and operating.
[00137] As described above, powered air can be supplied to both burners 100,
150 by a
common venturi enclosure 152 (see Fig. 7A). In some alternative embodiments,
one of the
burners can be coupled to a powered source of air, and can be coupled to the
other burner
through an air supply conduit in order to feed air to the other burner. An
example of such
an alternative embodiment is illustrated in FIG. 10. In the illustrated
embodiment of FIG.
10, powered air is supplied to the interior of the first burner 250 through a
port 252, an air
supply conduit 254, and a side of the outer tube 256 of the first burner 250.
Air is supplied
to the second burner 262 through another port (not shown) in the outer tube
256 of the first
burner 250, through another air supply conduit 258, and through the side of
the outer tube
260 of the second burner 262.
[00138] While the illustrated embodiments of FIGS. 7A-10 each have a pair of
burners
100, 150, 250, 262, other embodiments can utilize more than two burners by
interconnecting additional contiguous burners (e.g., through any combination
of common or
CA 02783217 2012-06-29
42
connected mounting plates 104, common or connected support plates 184, venturi
enclosure(s) 152 shared by burners, flame ignition conduits 212 extending
between burners,
and/or air supply conduits 258 extending between burners as described above
and illustrated
in the figures). Furthermore, although a common source of powered air can be
used to
supply air to two or more burners 110, 150, 250, 262 (as shown in the
illustrated
embodiments), air can be supplied to the individual burners 100, 150, 250, 262
on an
individual basis. Additionally, the burners 100, 150 and 250, 262 of the
burner assemblies
described and illustrated herein are of the same size. However, in other
embodiments, the
burners 100, 150 and 250, 262 can be different in size (e.g., the second
burner 150, 262 can
be smaller than the first burner 100, 250 in applications in which the first
burner 100, 250
supplies an inlet tunnel segment 20A, 20B of the oven 20 and the second burner
150, 262
supplies the outlet tunnel segment 20B, 20A of the oven 20).
[00139] Returning now to the design of burner 100 illustrated in FIG. 6, it is
noted that
the burner 100 has the ability to produce heat in an unusually wide BTU range.
In this
regard, it should be noted that burners of this general type typically operate
at an air to gas
ratio variability of 3:1. However, the relatively low BTU draw required of
burners in some
applications according to the present invention (e.g., in more efficient ovens
20 employing
one or more features of the present invention described earlier) can call for
an air to gas
ratio variability as low as 6:1. Such a lean fuel mixture can result in flame
lift-off from
conventional burners. Also, a rich air to gas ratio can result in poor
combustion. By
employing the burner features described above, including a reduced primary air
input at the
proximal end 112 of the venturi tube 106, a secondary air supply (e.g., via
gaps 123, 125 in
the illustrated embodiments), and/or the air openings 132 in the flame tube
130, a much
richer gas supply can be provided to the burners 110, 150, 250, 262. Also, it
has been found
that reduced primary air, combined with the addition of the secondary air
supply and the
flame tube air openings 132 supports a reduced gas supply level, and hence a
reduced BTU
production without flame lift off or dirty burning (encountered when there is
insufficient
oxygen to support the flame 134).
[00140] FIG. I 1 is a top plan view of selected elements of the oven 20
illustrated in
FIGS. 1-4. Gas inlets 251, 253 are coupled to and supply gas to the gas supply
tubes 170,
CA 02783217 2012-06-29
43
172, respectively (all of which are shown on the outside of the front wall 254
of the oven
20), which lead to the burners 102, 102' (see FIGS. 7A and 7B). Also, the
blower 155
supplies air to the venturi enclosure 152 via the air inlet 154 as described
above. Extending
from the other side of the front wall 254 are the flame tubes 130 and 130'. A
barrier 258 is
located at the distal ends 256 and 256' of the flame tubes 130, 130' and is
positioned
between the two flame tubes 130, 130'. The barrier 258 can be a plate or any
other
structure separating the flames 134 of the two tube flame tubes 130, 130' from
each other.
Alternatively or in addition, the barrier 258 can be positioned to separate
the heater plenums
68, 70 from each other (e.g., can extend downwardly between the heater plenums
68, 70 in
the illustrated embodiment of FIG. 11), so that heat produced by the first
burner 100
associated with one flame tube 130 is directed into one heater plenum 70, and
heat produced
by the second burner 150 associated with the other flame tube 130' is directed
into the other
heater plenum 68.
Operator interface
[00141] FIG. 17 is a schematic illustration of an alternative embodiment of
the control
system for the oven 20. In the illustrated embodiment of FIG. 17, a
microprocessor-based
controller 42' (e.g., model FPO-C14 manufactured by Panasonic) can be coupled
to a
separate operator interface 690 (e.g., model GT-30 manufactured by Panasonic).
Alternatively, the controller 42' and the operator interface 690 can be
incorporated into the
same unit, if desired. The operator interface 690 can include a touchscreen
display for
displaying data from and/or inputting data to the controller 42'.
[00142] In some embodiments, the operator interface 690 can include a color
liquid
crystal display ("LCD") and can have a diagonal screen size of 5.7". The
resolution of the
display can be 320 pixels by 240 pixels and can support sixteen colors. Other
embodiments
of the operator interface 690 can include a monochrome display and/or can be
of other
sizes, color depths, and resolutions.
[00143] FIGS. 18 to 23 illustrate displays for monitoring and controlling the
oven 20
according to an embodiment of the present invention. In some embodiments, the
operator
CA 02783217 2012-06-29
44
interface 690 includes two or more different screens for access by a user
(e.g., oven
operator, oven service or setup personnel, and/or oven manufacturers) in order
to control
operation of the oven 20. A significant advantage of this feature is the
ability to hide one or
more screens from some users (e.g., oven operators), while still enabling
other users (e.g.,
oven service or setup personnel and/or oven manufacturers) to access and
adjust controls of
the oven 20. Screens and user operable controls can be hidden from users by
the use of
buttons or other icons that are not normally visible on the operator interface
690, by
password protection, and the like.
[00144] The use of multiple screens enables users to quickly access a greater
number of
controls organized in an intuitive and logical manner, thereby providing the
user with
enhanced control over oven operation. In some embodiments, multiple screens
having
respective user-operable controls can be navigated by selecting buttons or
other icons on the
interface 690. Such screens can resemble windows, or can have any other
appearance and
format desired.
[001451 FIGS. 18A and 18B show two embodiments of a main screen 700 of the
operator
interface 690. The main screen 700 can include an on/off button 705. In some
embodiments, the on/off button 705 can be a first color (e.g., red) or shade
when the oven
20 is off and can be a second color (e.g., green) or shade when the oven 20 is
on. In these
and other embodiments, text or symbols of the on/off button 705 can change to
indicate
whether the oven 20 is on or off. Pressing the on/off button 705 when the oven
20 is off can
signal the controller 42' to turn the burners 60 and 62 and the fans 72 and 74
on. The oven
20 can then warm up to a predetermined temperature under control of the
controller 42'.
Pressing the on/off button 705 when the oven 20 is on can signal the
controller 42' to turn
off the burners 60, 62 and/or fans 72, 74. In some embodiments, the controller
42' turns off
the fans 72, 74 only if the temperature of the oven 20 is below a
predetermined threshold.
In such embodiments, if the temperature of the oven 20 is above the
predetermined
threshold, the controller 42' can continue to run the fans 72, 74 until the
temperature of the
over 20 falls below the predetermined temperature.
CA 02783217 2012-06-29
[00146] In some embodiments of the oven 20, the conveyor 22 can include a
single belt.
When the oven 20 is on, the operator interface 690 can display a belt #1 speed
indicator/button 710. In some embodiments, the speed of belt #1 can be shown
in minutes
and seconds, and can indicate the length of time an item placed on the
conveyor 22 takes to
traverse through the oven 20, In some embodiments of the oven 20, the conveyor
22 can
include a second belt, belt #2. PIG, 18B illustrates an embodiment of a main
screen 700 for
an oven 20 with a conveyor 22 including two belts. A belt #2 speed
indicator/button 715
can show the speed of belt #2 in minutes and seconds. In ovens 20 with two
side-by-side
belts, the speed of belt #1 can indicate the time an item placed on a first
conveyor 22 takes
to traverse through the oven 20, whereas the speed of belt #2 can indicate the
time an item
placed on a second conveyor 22 takes to traverse through the oven 20. In those
embodiments in which the conveyors 22 are placed in an end-to-end arrangement,
the sum
of the times for belt #1 and for belt #2 can indicate the length of time an
item takes to
traverse the plenums 68 and 70 of the oven 20.
[00147] Pressing the speed of belt #1 indicator/button 710 can, in some
embodiments,
display a data entry screen (not shown) to enable modification of the speed
setting for belt
#1. The data entry screen can display a keypad, a scroll bar, radio buttons,
dials, slides, or
any other user control allowing an operator to enter a new data value. The
data entry screen
can have an enter button which can enter a new data value and return to the
previous screen,
and can also have a cancel button which can return to the previous screen 755
without
modifying the data value. Pressing the speed of belt #2 indicator/button 715
can, in some
embodiments, display a data entry screen to allow modification of the speed
setting for belt
#2 in any of the manners just described in connection with the speed of belt
#1
indicator/button 710.
[001481 In some embodiments, a first bar graph 720 can be displayed along the
left side
of the main screen 700, and can indicate the percentage of time the first
burner 60 has been
on during the period the oven 20 has been on. Also or alternatively, a first
alphanumeric
display 725 can show the percentage of time the first burner 60 has been on.
In those
embodiments in which the first alphanumeric display 725 is used in conjunction
with the
first bar graph 720, the first alphanumeric display 725 can be located
anywhere adjacent the
CA 02783217 2012-06-29
46
first bar graph 720, such as above the first bar graph 720 as shown in FIGS.
18A and 18B.
In some embodiments, the first bar graph 720 and/or the first alphanumeric
display 725 can
be a first color (e.g., green) or shade when the percentage is below a
predetermined
threshold and can be a second color (e.g., red) or shade when the percentage
is above the
predetermined threshold. If desired, the first bar graph 720 and/or the first
alphanumeric
display 725 can be displayed in a plurality of colors to indicate additional
thresholds or
ranges.
[00149] In some embodiments a second bar graph 730 can be displayed along the
right
side of the main screen 700 and can indicate the percentage of time the second
burner 62
has been on during the period the oven 20 has been on. Also or alternatively,
a second
alphanumeric display 735 can show the percentage of time the second burner 62
has been
on. In those embodiments in which the second alphanumeric display 735 is used
in
conjunction with the second bar graph 730, the second alphanumeric display 735
can be
located anywhere adjacent the second bar graph 730, such as above the second
bar graph
730 as shown in FIGS. 18A and 18B. In some embodiments, the second bar graph
730
and/or the second alphanumeric display 735 can be a first color (e.g., green)
or shade when
the percentage is below a predetermined threshold and can be a second color
(e.g., red) or
shade when the percentage is above the predetermined threshold. If desired,
the second bar
graph 730 and/or the second alphanumeric display 735 can be displayed in a
plurality of
colors to indicate additional thresholds or ranges.
[001501 It will be appreciated that the information provided by first and
second bar
graphs 720, 730 can be displayed in a number of other forms, including without
limitation
by pie charts, a series of ramped bars, and the like. Also, the location and
size of the first
and second bar graphs 720, 730 shown in FIGS. 18A and 18B are presented by way
of
example only, and can be different in other embodiments.
[00151] In some embodiments, the main screen 700 can also include a message
display
740 for displaying operating (e.g., energy mode) and/or error messages. Also,
the main
screen 700 can include a time display 745. The message and time displays 740,
745 can
have any size and can be located anywhere on the main screen 700 as desired.
CA 02783217 2012-06-29
47
[00152] The main screen 700, in some embodiments, can include a temperature
display/button 750 which can show a temperature of the oven. The temperature
displayed
can be that of either plenum 68, 70, or can be an average temperature of the
plenums 68, 70.
In some embodiments, two temperature displays are provided, each showing a
temperature
of a respective portion of the oven 20. Also, in some embodiments, pressing
the
temperature display/button 750 can display a temperature setting screen 755
(FIG. 19,
described in greater detail below).
[00153] In some embodiments, the main screen 700 can include one or more
buttons for
accessing one or more oven set-up screens. The buttons can be visible or
invisible, and can
be password protected, if desired. In the illustrated embodiment of FIGS. 18A
and 18B, for
example, the main screen 700 includes three hidden buttons 760, 765, and 770
to access
respective set-up screens. The hidden buttons 760, 765, and 770 have no
visible features
displayed on the main screen 700, but react when pressed. The first hidden
button 760 can
provide access to a temperature tuning screen 775 (FIG. 20). The second hidden
button 765
can provide access to a belt tuning screen 777 (FIG. 21) and the third hidden
button 770 can
provide access to a belt set-up screen 778 (FIG. 22). Ovens 20 according to
embodiments
of the present invention can have any one or more (or none) of these screens
775, 777, 778.
[00154] FIG. 19 illustrates a temperature setting screen 755 according to an
embodiment
of the present invention. The temperature setting screen 755 can display the
first bar graph
720, the second bar graph 730, the first alphanumeric display 725, and the
second
alphanumeric display 735 in a manner similar to that discussed previously with
regard to the
main screen 700. The temperature setting screen 755 can also display actual
and/or desired
temperatures for one or more portions of the oven 20. For example, the
temperature setting
screen 755 illustrated in FIGS. 18A and 18B can display a first actual
temperature 780
indicating the temperature in the left oven segment 20A, and a second actual
temperature
785 indicating the temperature in the right oven segment 20B. The temperature
setting
screen 755 can also or instead display a first temperature setpoint 790 for
the left oven
segment 20A and a second temperature setpoint 795 for the right oven segment
20B.
CA 02783217 2012-06-29
48
[00155] The temperature setpoints can be target temperatures that the
controller 42' can
attempt to maintain in each oven segment 20A, 20B. In some embodiments,
pressing the
first temperature setpoint display 790 for the left oven segment 20A can
display a data entry
screen (as discussed previously) to allow modification of the first
temperature setpoint,
while pressing the second temperature setpoint display 795 for the right oven
segment 20B
can also display a temperature entry screen (as discussed previously) to allow
modification
of the.second temperature setpoint. The temperature setting screen 755 can
also be
provided with a back button 800 that can be pressed to display the main screen
700.
[00156] With reference again to the illustrated embodiment of the main screen
700 in
FIGS. 18A and 18B, pressing the hidden button 760 on the main screen 700 of
the operator
interface 690 can display a temperature tuning screen 775 as shown in FIG. 20.
The
temperature tuning screen 775 can enable an operator to monitor and modify
control
parameters of the oven 20. Some embodiments of the oven 20 can use a
proportional
integral derivative ("PID") control scheme. For example, the controller 42'
can utilize a
PID control scheme for controlling the burners 60 and 62. The PID control
scheme enables
the controller 42' to achieve and maintain the temperatures within the oven
segments 20A,
20B close to their temperature setpoints.
[00157] In some embodiments, the temperature tuning screen 775 can include one
or
more PID displays for one or more respective burners 60, 62 of the oven 20.
For example,
in the illustrated embodiment of FIG. 20, the temperature tuning screen 775
displays a
burner #1 proportional gain indicator/button 810, a burner #1 integral time
indicator/button
815, a burner #1 derivative time indicator/button 820, and a burner #1 control
cycle time-
indicator/button 825. In some embodiments, an operator can press any of these
indicators
810, 815, 820, 825 to display a data entry screen (as discussed previously),
thereby allowing
modification of each parameter. Alternatively or in addition, pressing a
burner #1 autotune
button 830 can instruct the controller 42' to perform an autotuning function
that can
automatically determine the optimum value for each of the parameters.
[00158] The temperature tuning screen 775 can also display a burner #2
proportional
gain indicator/button 835, a burner #2 integral time indicator/button 840, a
burner #2
CA 02783217 2012-06-29
49
derivative time indicator/button 845, and a burner #2 control cycle time
indicator/button
850. In some embodiments, an operator can press any of these indicators 835,
840, 40,845,
850 to display a data entry screen (as discussed previously), thereby allowing
modification
of each parameter. Alternatively or in addition, pressing a burner #2 autotune
button 855
can instruct the controller 42' to perform an autotuning function that can
automatically
determine the optimum value for each of the parameters.
[001591 In some embodiments, the temperature tuning screen 775 can display one
or
more buttons for accessing set-up screens for energy saving modes. It will be
appreciated
that such buttons can also or instead be located on other screens of the
operator interface
690. With reference to the embodiment of FIG. 20, an energy saving mode #2
button 860
can access an energy saving mode #2 screen 865 (FIG. 23A). The energy saving
mode #2
screen 865 can display the time that the oven 20 is to remain in energy saving
mode #2 once
the oven 20 enters energy saving mode #2. The energy saving mode #2 screen 865
can
include a mode #2 hours indicator/button 870, a mode #2 minutes
indicator/button 875, and
a mode #2 seconds indicator/button 880. In some embodiments, pressing any of
these
indicator/buttons 870, 875, 880 can display a data entry screen (as discussed
previously),
enabling an operator to modify the time setting for energy saving mode Q. The
energy
saving mode #2 screen 865 can also be provided with a back button 800 for
returning to the
temperature tuning screen 775.
[001601 The temperature tuning screen 775 can also display an energy saving
mode #3
button 885. Pressing the energy saving mode #3 button 885 can access an energy
saving
mode #3 screen 890 (FIG. 23B). The energy saving mode #3 screen 890 can
display the
time that the oven 20 is to remain in energy saving mode #3 once the oven 20
enters energy
saving mode #3. The energy saving mode #3 screen 890 can include a mode #3
hours
indicator/button 895, a mode #3 minutes indicator/button 900, and a mode #3
seconds
indicator/button 905. In some embodiments, pressing any of the
indicator/buttons 895, 900,
905 can display a data entry screen (as discussed previously), enabling an
operator to
modify the time setting for energy saving mode #3. The energy saving mode #3
screen 890
can also be provided with a back button 800 for returning to the temperature
tuning screen
775.
CA 02783217 2012-06-29
[00161] The temperature tuning screen 775 can also display an energy saving
mode #4
button 910. Pressing the energy saving mode #4 button 910 can access an energy
saving
mode #4 screen 915 (FIG. 23C). The energy saving mode #4 screen 915 can
display the
time that the oven 20 is to remain in energy saving mode #4 once the oven 20.
enters energy
saving mode #4. The energy saving mode #4 screen 915 can include a mode #4
hours
indicator/button 920, a mode #4 minutes indicator/button 925, and a mode #4
seconds
indicator/button 930. In some embodiments, pressing any of the
indicator/buttons 920, 925,
930 can display a data entry screen (as discussed previously), enabling an
operator to
modify the time setting for energy saving mode #4. The energy saving mode #4
screen 915
can also be provided with a back button 800 for returning to the temperature
tuning screen
775.
[00162] In some embodiments, the main screen 700 is provided with a back
button 800,
which can be pressed to return the user to the main screen 700.
[001631 With reference again to the illustrated embodiment of the main screen
700 in
FIGS. 18A and 18B, pressing the second hidden button 765 on the main screen
700 of the
operator interface 690 can display a belt tuning screen 777 (FIGS. 21 A and 21
B). FIG. 21A
is an embodiment of a display for an oven 20 having a single belt, and FIG. 21
B is an
embodiment of a display for an oven 20 having two belts. As with temperature
control of
the oven 20 described above, some embodiments of the controller 42' can
control the
operation of the belts using a PID control scheme. The belt tuning screen 777
can enable an
operator to monitor and modify the parameters of the PID control.
1001641 The belt tuning screen 777 illustrated in FIG. 21A displays a front
belt
proportional gain indicator/button 93 5, a front belt integral time
indicator/button 940, a
front belt derivative time indicator/button 945, and a front belt control
cycle time
indicator/button 950. In some embodiments, an operator can press any of these
indicator/buttons 935, 940, 945, 950 to display an entry screen, thereby
enabling the
operator to modify each parameter. Alternatively or in addition, pressing a
front belt
autotune button 955 can instruct the controller 42' to perform an autotuning
function that
can automatically determine the optimum value for each of the parameters.
CA 02783217 2012-06-29
51
[00165] The belt tuning screen 777 for an oven 20 with two belts can also
display a back
belt proportional gain indicator/button 960, a back belt integral time
indicator/button 965, a
back belt derivative time indicator/button 970, and a back belt control cycle
time
indicator/button 975. An operator can press any of these indicators 960, 965,
970, 975 to
display an entry screen, thereby enabling the operator to modify each
parameter.
Alternatively or in addition, pressing a back belt autotune button 980 can
instruct the
controller 42' to perform an autotuning function that can automatically
determine the
optimum value for each of the parameters.
[00166] In some embodiments, the belt tuning screen 777 is provided with a
back button
800, which can be pressed to return the user to the main screen 700.
[00167] With reference again to the illustrated embodiment of the main screen
700 in
FIGS. 18A and 18B, pressing the third hidden button 770 on the main screen 700
can
display a belt set-up screen 778 (see FIG. 22). In some embodiments, the belt
set-up screen
displays different buttons for two or more different belt lengths of the belts
used in the
conveyor 20. In the illustrated embodiment of FIG. 22, for example, the belt
set-up screen
778 displays three buttons 1000, 1005, 1010 representing different belt
lengths for a front
belt of the conveyor 22, and three buttons 1015, 1020, 1025 representing
different belt
lengths for a back belt of the conveyor 22. The buttons can represent a front
belt short-
length belt 1000, a front belt mid-length belt 1005, a front belt long-length
belt 1010, a back
belt short-length belt 1015, a back belt mid-length belt 1020, and a back belt
long-length
belt 1025.
[00168] In some embodiments the button for the belt length selected for each
belt can be
displayed in a first color (e.g., green) or shade, and the buttons for the
belt lengths not
selected can be displayed in a second color (e.g., red) or shade. Pressing a
button that is not
presently selected can make the belt length associated with the pressed button
become the
active belt length, and can deselect the belt length previously selected.
Pressing a button
that is already selected for at least one of the belts of the conveyor 22 can
deselect the belt
length associated with that button, placing that belt into an inactive mode
(e.g., a mode
where the oven 20 has only one belt). In some embodiments, pressing a button
that is
CA 02783217 2012-06-29
52
already selected for one of the belts of the conveyor 22 has no impact on the
oven 20. Also,
in some embodiments, a front belt active display 1030 and a back belt active
display 1035
can display in a first color (e.g., green) or shade when a belt length has
been selected for
that belt and can display in a second color (e.g., red) or shade when no belt
length is
selected. In these and other embodiments, text associated with the front belt
length and the
back belt length can change to indicate whether a belt length has been
selected or no belt
length has been selected. In some embodiments, the belt set-up screen 778 is
provided with
a back button 800, which can be pressed to return the user to the main screen
700.
[00169] The embodiments described above and illustrated in the figures are
presented by
way of example only and are not intended as a limitation upon the concepts and
principles
of the present invention. As such, it will be appreciated by one having
ordinary skill in the
art that various changes in the elements and their configuration and
arrangement are
possible without departing from the spirit and scope of the present invention
as set forth in
the appended claims. For example, the oven controller 42 in a number of the
embodiments
described above is responsive to one or more temperature sensors 80, 82 and/or
position
sensors 79, 81, 83, 85 by changing the BTU output of one or more burners 60,
62 and/or by
changing the speed of one or more fans 72, 74. In these and other embodiments,
the
controller 42 can be responsive to an amount of conveyor movement detected by
one or
more suitable sensors (e.g., rotary encoder(s), other optical or mechanical
sensors positioned
to detect the amount of movement of the conveyor, and the like). In this
manner, such
sensor(s) can send signals to the controller 42 to change the BTU output of
one or more
burners 60, 62 and/or to change the speed of one or more fans 72, 74 based
upon the amount
of movement of the conveyor 22 - and therefore the amount of movement of a
pizza or
other food on the conveyor 22.
