Note: Descriptions are shown in the official language in which they were submitted.
CA 02530965 2009-12-15
METHOD AND STEAMING OVEN AND COLLECTOR PLATE
FIELD OF THE INVENTION
This invention relates to a method and a steaming oven having a
collector plate that collects and disposes of waste material from cooking food
products with steam.
BACKGROUND OF THE INVENTION
Sub-atmospheric cook-and-hold steaming ovens are known. For
example, U.S. Patent No. 5,235,903 discloses an open topped water holding
tray that is disposed at the bottom of the oven. The oven includes means to
heat the water to provide steam for cooking and/or holding food products
warm and moist. A manually operated drain valve is provided near the
lowermost portion of the water tray. An optional grease catching pan is
disposed between the racks of the oven and the water tray. The drain valve is
manually operated to periodically drain the water tray.
The grease catching pan catches droppings (e.g., condensed steam
entrained with food protein, food scraps and other undesirable materials) that
drip from food being cooked in the oven. This prevents the droppings from
one food batch entering the water tray, which could cause foam to develop in
the steaming compartment. The foam could then spill from the cooking
compartment when the door is opened, thereby causing slipping hazards and
other undesirable effects. Although the grease catching pan catches the
droppings, an operator needs to keep a close watch to empty the pan before it
fills and overflows into the water tray.
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Drip pans with a drain tube are also known. For example, U.S. Patent
No. 4,773,319 discloses a drip pan that is sloped to guide droppings to a
channel leading to a drain tube that exits the cooking chamber. This
arrangement is disposed between the grill or grate and the flames of a burner
so as to minimize flaming due to grease droppings.
It is also known to provide a water tray with an overflow control. For
example, U.S. Patent No. 2,097,793 discloses a water tray that serves the
dual function of providing steam to the cooking chamber and the collection of
waste droppings. A funnel is disposed in the tray to direct the waste
droppings
and water to a catch pan as the water/grease level exceeds the height of the
funnel. The dual function water tray has the disadvantage that waste
contaminants enter the boiling water tray, which in turn contaminates food
cooked in later batches with the tastes or residues of previously cooked
items.
There is a need for an improved steaming oven and droppings removal
system.
There is also a need for providing turbulence free water level
measurements.
SUMMARY OF THE INVENTION
A steaming oven of the present invention comprises an oven chamber
and a water reservoir disposed in the oven chamber to provide steam therein.
At least one water level probe or sensor is located to sense a water level in
the
water reservoir. A barrier is located at least partially in the water
reservoir to
provide a quiet zone about said water level probe. The water level is
stabilized in the quiet zone despite water turbulence outside said quiet zone.
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In one embodiment of the steaming oven of the present invention, the
barrier comprises a wall that extends at least partially below the water
level.
In another embodiment of the steaming oven of the present invention, a
tab is located to one side of the water level probe to provide additional
shielding from the water turbulence. Preferably, the water level probe is
disposed at a side of the water reservoir. The tab is preferably angled toward
the side.
In another embodiment of the steaming oven of the present invention,
another tab that is located to the opposite side of the probe to provide
further
shielding from the water turbulence.
In another embodiment of the steaming oven of the present invention, a
collector plate is positioned above the water level.
Preferably, the barrier is attached to the collector plate by a fastener
selected from the group consisting of: weldment, bolts, screws, adhesives, a
form press fit construction or a combination thereof.
In another embodiment of the steaming oven of the present invention, a
conduit is positioned to convey waste material collected by the collector
plate
from the oven chamber. The conduit is at least partially disposed in the water
reservoir.
In another embodiment of the steaming oven of the present invention,
an opening of the conduit is above the water level in the reservoir and waste
material is conveyed to the opening of the conduit.
In another embodiment of the steaming oven of the present invention,
the opening is in registry with a drain of the collector plate.
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In another embodiment of the steaming oven of the present invention,
the waste material is conveyed from the oven via the drain, the conduit and an
exit hole.
In another embodiment of the steaming oven of the present invention,
the barrier wall and at least one of the tabs is a single unitary piece.
The method of the present invention provides steam in a steaming
oven. The steam is provided from a water reservoir. A water level in the
water reservoir is sensed with at least one water level probe or sensor. The
water level probe is shielded from water turbulence in the water reservoir to
provide a sensed water level without substantial interference from the water
turbulence.
In one embodiment of the method of the present invention, the shielding
step shields the water level probe with a barrier.
BRIEF DESCRIPTION OF THE DRAWINGS
Other and further objects, advantages and features of the present
invention will be understood by reference to the following specification in
conjunction with the accompanying drawings, in which like reference
characters denote like elements of structure and:
FIG. 1 is a front view of a steaming oven of the present invention with
the front door removed;
Fig. 2 is a view along the line-2 of Fig. 1;
Fig. 3 is a view along the line 3 of Fig. 1;
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Fig. 4 is a perspective view of the collector plate of the oven of Fig. 1;
Fig. 5 is a perspective view of an alternative embodiment. of the
collector plate of the oven of Fig. 1;
Fig. 6 is a perspective view of an alternate embodiment of the collector
plate of the oven of Fig. 1; and
Fig. 7 is a view similar to Fig. 3 except with the collector plate of Fig. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As used herein, steaming oven is intended to include any cooking oven
that uses steam in whole or in part to cook. For example, the oven may use
steam only or steam in combination with convection, conduction or other
thermal transfer. Thus, the steaming oven of the present invention includes,
for example, steam ovens as well as convection ovens, microwave ovens or
combinations thereof that also employ steam.
Referring to Figs. 1-3, a steaming oven 20 of the present invention
includes a housing 22 that supports a cooking chamber 24 and a region 26 for
such items as controls, a blower fan, and/or a microwave energy source (none
of which is shown). Oven chamber 24 includes a rack holder 28, a reservoir
30, and a collector plate 32. Rack holder 28 holds a rack (not shown) upon
which food may be located for cooking. It will be apparent to those skilled in
the art that rack holder 28 may include additional holders to hold more than
one rack.
Reservoir 30 is formed by the bottom and four sides of oven chamber
24 to hold water 34. It will be apparent to those skilled in the art that
reservoir
30 may be a separate tray or other vessel. An overfill tube 31 is disposed in
reservoir 30 to prevent water 34 from exceeding a predetermined level therein.
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Reservoir 30 comprises a water fill valve (not shown) and a drain 48.
The water fill valve may be manually operated or automatically operated in
response to a water level probe or sensor 122 or 124 (shown in Fig. 7) that
senses water level in reservoir 30. Drain 48 may be interconnected with
tubing and a drain valve (neither being shown) to drain water 34 from
reservoir
30. Overfill tube 31 is connected via an oven exit hole 50 to drain water 34
and waste material to an external drain or vessel.
A heater 36 is disposed in region 26 in a location to heat reservoir 30 so
as to boil water 34, thereby producing steam. For example, heater 36 may be
disposed below reservoir 30. Heater 36 may be an electrical heater, a gas
burner or other heater suitable for heating reservoir 30 to boil water 34.
Collector plate 32 is disposed in oven chamber 24 above reservoir 30
so as to prevent waste material from falling into reservoir 30 and
contaminating water 34. Thus, collector plate 32 is large enough to catch
waste material produced by cooking and small enough to allow steam from
reservoir 30 to rise in oven chamber 24 for cooking. To this end, collector
plate 32 is shorter in width and length than reservoir 30 to form a passage 38
as a border between collector plate 32 and the perimeter of reservoir 30 to
allow steam to rise and fill oven chamber 24. Passage 38 is formed on the
sides and back of oven chamber 24, but could just as well also be formed on
the front thereof. It will be apparent to those skilled in the art that
passage 38
can be along more or less than three sides of collector plate 32 or could even
be formed by perforations in a border of collector plate 32.
The waste material, for example, includes solid and liquid droppings
from the food being cooked as well as condensed steam droplets. The
droppings may be directly from the food or from solid or perforated pans
holding the food.
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Referring also to Fig. 4, collector plate 32 has a retaining lip 40 on its
side and rear edges and a drain tube 42. Lip 40 retains and directs the waste
material fluid to drain tube 42. The back corners of collector plate 32 are
sealed to prevent leakage of the waste material fluid.
Collector plate 32 has a support 44 along a front edge thereof and a
support 46 at the back corner that is remote from the location of drain tube
42.
Supports 44 and 46 act to position collector plate 32 within oven chamber 24
so that drain tube 42 is in registry with overfill tube 31 of reservoir 30
(best
seen in Figs. 1 and 2). Drain tube 42 has a smaller diameter than that of
overfill tube 31 so that drain tube 42 extends removably into overfill tube
31.
Overfill tube 31, front support 44 and back corner support 46 are dimensioned
so that when installed in oven chamber 24, collector plate 32 slopes
downwardly toward drain tube 42 so that the waste material flows by gravity
along the surface of collector plate 32 to drain tube 42. For example, front
support 44 and back comer support 46 can be higher than overfill tube 42.
Alternatively, the sloping can be achieved, for example, by different
elevations
of the areas within reservoir 30 upon which supports 44 and 46 rest.
Overfill tube 42 is high enough to provide additional support for collector
plate 32. Alternatively, an additional back support can be provided at any
suitable location, such as, for example, the back comer that is opposite back
support 46. Drain tube 42 is designed to fit loosely in overfill tube 31 to
facilitate easy installation and removal for cleaning purposes. Preferably,
the
highest point of collector plate 32 is at the front of oven chamber 24 and
below
the door opening. This assures that oven chamber 24 cannot be flooded (and
injure a person opening the door) in the case of a malfunctioning water fill
valve (not shown).
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Referring to Fig. 5, an alternative collector plate 60 of the present
invention is shown. Collector plate 60 has a drain screen 62 that is
positioned
over a drain tube not shown in Fig. 5. Drain screen 62 traps oversize waste
particles that might otherwise clog the drain tube, overfill tube 31 and/or
other
tubing in the drain system.
Collector plate 60 also has a front support 64 and a back support 68.
Front support 64 has an opening 66 that allows manual filling of water into
reservoir 30 without removal of collector plate 60. Back support 68 is
constructed of tubing that affords robust support for collector plate 60. The
tubing may be any desired shape, such as the square shape shown in Fig. 5.
Steaming oven 20 of the present invention provides several
advantages. Collector plate 32 prevents contaminants from entering reservoir
30, which in turn prevents those materials from contaminating food cooked in
later batches with the tastes or residues of previously cooked items. The
removal of contaminants from reservoir 30 significantly reduces the potential
for generating foam in oven chamber 24. This foam can spill from oven
chamber 24 when the door is opened. This can cause slipping hazards and
other undesirable effects. Overfill tube 31 also provides a safety overflow
drain to prevent oven .chamber 24 from flooding in the event of component
failure in the automatic water fill system. If oven chamber 24 flooded and an
operator opened the door, there would be a potential for serious injury, both
from the hot water itself and also from the potential slipping hazard of water
on
the floor. Collector plates 32 and 60 may be fabricated from any suitable
material, such as metal, plastic and the like. Preferably, collector plates 32
and 60 are stainless steel. Also, collector plates 32 and 60 are preferably
removable for ease of cleaning. Collector plates 32 and 60 may be designed
to be "self-positioning" when installed in the cooking compartment. Removal
of the contaminants before they enter water reservoir 30 reduces the amount
of reservoir cleaning that is required. Gap 38 between collector plate 32 and
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the sides of the oven chamber 24 provide space for improved steam
circulation, leading to better cooking performance.
Referring to Fig. 6, an alternative collector plate 100 of the present
invention has a retaining lip 140 on its side and rear edges and a drain tube
142. Lip 140 retains and directs the waste material fluid to drain tube 142.
The back comers of collector plate 100 are sealed to prevent leakage of the
waste material fluid.
Collector plate 100 has a front support 104 along a front edge thereof
and a back support 106 at a suitable location, for example, the back comer
that is remote from the location of drain tube 142. Supports 104 and 106 act.
to position collector plate 100 within oven chamber 24 so that drain tube 142
is
in registry with overfill tube 31 of reservoir 30 (best seen in Figs. I and
2).
Front support 104 is adjacent an opening 110 that allows manual filling of
water into reservoir 30 without removal of collector plate 100. Drain tube 142
has a smaller diameter than that of overfill tube 31 so that drain tube 142
extends removably into overfill tube 31. Overfill tube 31, front support 104
and
back corner support 106 are dimensioned so that when installed in oven
chamber 24, collector plate 100 slopes downwardly toward drain tube 142 so
that the waste material flows by gravity along the surface of collector plate
100
to drain tube 142. For example, front support 104 and back comer support
106 can be higher than overfill tube 142. Alternatively, the sloping can be
achieved, for example, by different elevations of the areas within reservoir
30
upon which supports 104 and 106 rest.
Overfill tube 31 is high enough to provide additional support for collector
plate 100. Alternatively, an additional back support can be provided at any
suitable location, such as, for example, the back corner that is opposite back
support 106. Drain tube 142 is designed to fit loosely in overfill tube 31 to
facilitate easy installation and removal for cleaning purposes. Preferably,
the
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highest point of collector plate 100 is at the front of oven chamber 24 and
below the door opening. This assures that oven chamber 24 cannot be
flooded (and injure a person opening the door) in the case of a malfunctioning
water fill valve (not shown).
Referring to Figs. 6 and 7, a barrier that includes a barrier wall 120
provides a quiet zone around a pair of water level probes or sensors 122 and
124 disposed in reservoir 30, thereby shielding the water level probes from
water turbulence. Water level probe or sensor 122 is vertically positioned to
sense a low water level and in response to provide a signal that interrupts
heating source 36 until such time as the water level reaches a minimum
permitted operating level in reservoir 30. On the other hand, water level
probe
or sensor 124 is positioned vertically to sense a high water level and in
response to provide a signal that turns the water supply valve off, the water
supply valve being on when the water level is below the high water level.
Barrier wall 120 extends downwardly from an edge of collector plate 100 so as
to span a range of water levels that preferably includes the aforementioned
high and low water levels. Preferably, barrier wall is sized vertically to
provide
support for collector plate 100. Barrier wall 120 extends horizontally a
distance that encompasses water level probes 122 and 124.
Water level probes or sensors 122 and 124 are preferably located
adjacent one side of reservoir 30 and toward the front of the oven to
facilitate
cleaning through the oven door. For this preferred location, barrier wall 120
extends horizontally along the edge of collector plate 100 that faces water
level probes 122 and 124. Barrier wall 120 may extend around the front
comer of collector plate 100, but alternatively may end before the comer.
A tab 126 is located on one side of water level probes 122 and 124 and
a tab 128 is located on the other side to additionally shield water level
probes
122 and 124. For example, tab 126 is located on the side adjacent water level
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probe 122 and tab 128 is located on the side adjacent tab 124. Tab 126 is
angled toward the rear of collector plate 100 so as to divert water turbulence
away from the area of water probes 122 and 124, thereby improving water
level control through reliable water level measurements. Tab 126 also diverts
any fallen food particles not intercepted by collector plate 100 from fouling
water level probes 122 and 124.
Tab 126 is sized to maintain a predetermined clearance between
barrier wall 120 and water level probes 122 and 124 so as to prevent
accidental contact of water level probes 122 and/or 124 with barrier wall 120
and/or lip 120 of collector plate 100.
Barrier wall 120 and tabs 126 and 128 may be made as a single
integral piece or as a plurality of separate pieces. In either case, barrier
wall
120 and tabs 126 and 128 are affixed to collector plate 100 by a suitable
fastener. For example, the fastener may be a weldment, bolts, screws,
adhesives, a form press fit construction or a combination thereof.
The quiet zone has some beneficial effects on the over all operation of
steaming oven 20. For example, angled tab 126 shields the quiet zone by
diverting any debris that falls into reservoir 30 away from water level probes
122 and 124. Without the diversion, the debris could short out water level
probes 122 and/or 124 and result in steaming oven 20 running out of water.
Also, the stabilized water level can be more evenly controlled, thereby
resulting in a more even measurement of the actual water level. In the quiet
zone, surface tension allows for longer and more consistent contact between
water level probes 122 and/or 124 and the actual water level. This reduces
the number of cycles on and off experienced by the water fill solenoid and
increases the life of steaming oven 20 and reduces warranty cost on the
solenoid fill valve and water level probes 122 and 124.
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The present invention having been thus described with particular
reference to the preferred forms thereof, it will be obvious that various
changes and modifications may be made therein without departing from the
spirit and scope of the present invention as defined in the appended claims.
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