Note: Descriptions are shown in the official language in which they were submitted.
This inven~ion relates generally to cooking equipment
and deals more particiularly with an improved forced air
convection oven and a method of cooking food.
The various advantages of forced air convection ovens
are well known, as indicated in U. S. Patent No. 3,529,582 to
Hurko et al. Among the most significant benefits of this type
of oven is the reduced cooking time and the accompanying
decrease in power consumption which results from the forced
circulation of air within the oven. This benefit has taken on
increased importance in recent years due to the well known
problems relating to energy supplies.
Convection ovens such as that shown in the Hurko et
al patent employ a fan to pass air across an electrical heating
element and then into the oven compartment that contains the
foods which is to be cooked. In the past, one of the major
problems with this type of cooking operation has been to heat
the oven compartment in a uniform manner. Existing ovens
typically have a simple air distribution pattern which fails to
take into account the shape of the heating element, its
proximity to the fan, and other factors associated with the
geometry of the oven. As a result, the cooking compartment is
heated unevenly and the food is not always cooked in a uniform
manner. An uneven temperature distribution within the oven
also causes the development of "hot spots" which can pose a
serious safety problem and which further detract from the
effectiveness of the oven. Additional safety problems result
from the accessibility of the extremely hot area in the
vicinity of the heating element which can inadvertently be
contacted by the hands to cause severe burns.
Grease and other undesirable materials are generally
circulated throughout the cooking chambers of existing
convection ovens. This not only has an adverse effect on the
cooking operation but also grea-tly lncreases the difficulty
involved in cleaning the oven. In particular, the fan and the
heating element are exposed to grease and the like which tends
to collect in inaccessible areas of the oven which are
difficult if not impossible to clean thoroughly. Furthermore,
the physical appearance of existing convec~ion ovens suffers
from the presence of unsightly hinges and other compartments.
The present invention has as its primary goal the
provision of an improved convection oven which overcomes the
aforementioned problems.
More specifically, it is an important object of the
invention to provide a forced air convection oven and cooking
method which achieves substantially uniform heating of the
cooking compartment. Particularly significant in this respect
are the non-uniform si~e and non-symmetrical pattern of the
discharge openings in the diffuser panel. The discharge
openings are arranged to take full advantage of the oven
geometry and the configuration of the heating element and its
spacing relative to the fan blades and other oven components.
Another important object of the invention is to
provide a convection oven having a closed air circulation
system. Outside air is not drawn into the oven during
operation, and its efficiency is increased accordingly.
Still another object of the invention is to provide a
convection oven wherein the heating element and fan are
contained in a separate air chamber which is located above the
cooking compartment and which is physically isolated
therefrom. Consequently, there is no danger of the hottest
portion of the oven being contacted inadvertently by the
consumer.
An additional object of the invention is to provide a
convection oven which prevents grease and the like from
18~ S
circulating throughout the cooking chamber. A removable filter
element collects the grease and prevents it from soiling the
fan, heating element, and other components of the oven.
A further object of the invention is to provide in a
convection oven of the character described, a unique hinge
arrangement for the oven door which enhances the appearance of
the oven without adversely affecting proper functioning of the
door.
Yet another object of the invention is to provide a
convection oven of ~he character described wherein the oven
door has a unique double pane construction which affords good
insulation and structural strength while permitting observation
of the oven contents.
A still further object of the invention is to provide
a convection oven of the character described which is simple
and economical to manufacture and efficient in operationO
Other and further objects of the invention together
with the features of novelty appurtenant thereto, will appear
in the course of the following description.
~0 In the accompanying drawings which form a part of the
specification and are to be read in conjunction therewith and
in which like reference numerals are used to indicate like
parts in the various views:
Fig. 1 is a front elevational view of a forced air
convection oven constructed according to a preferred embodiment
of the present invention, with portions broken away for
purposes of illustration;
Fig. 2 is a sectional view of the oven taken
generally along line 2-2 of Fig. 1 in the direction of the
arrows;
Fig. 3 is a fragmentary sectional view taken
generally along line 3-3 of Fig. 2 in the direction of the
arrows, with po~tions broken away for ill~strative purposes,
Fig. '~ iS a fragmentary sectional view on an enlarged
scale taken generally along line 4-4 of Fig. 1 in the direction
of the arrows;
Fig. 5 is a fragmentary sectional view on an enlarged
scale taken generally along line 5-5 of Fig. 1 in the direction
of the arrows; and
Fig. 6 is a fragmentary sec-tional view taken
generally along line 6-6 of Fig. 3 in ~he direction of the
arrows.
With initial reference to Fig. 1, numeral 10
~enerally designates a forced air convection oven constructed
in accordance with the present invention. The oven 10 has a
box like housing which includes an outer shell 11 extending
along both sides and the top portion of the oven. Shell 11 is
suitably attached to a floor 12 which includes top and bottom
panels 13 and 1~ which may contain insulating material 15
therebetween. Padded feet 16 are secured to panel 14 and rest
on a counter top or the like.
Each side wall of the housing includes a sheet metal
panel 18 which is spaced inwardly of the corresponding wall of
shell 11. Insulating material 19 fills the space between each
side panel 18 and the corresponding wall of the shell. Each
panel 18 has a hori~ontal flange 20 on its lower edge which is
turned outwardly and secured at 20a to the side edge portions
of floor panels 13 and 14. As shown in Fig. 2, the back wall
of the housing is formed similarly, having a panel member 21
exposed to the interior of the oven. Upper and lower flanges
22 and 23 are secured to the top portion of the housing and to
floor 12 by a screw 22a extending through housing plate 45,
back panel 24 and then connects to flange 26. Similarly, and
at the bottom, flange 23 via screw 23a secures flange 23 to
f~8~15
panel 13. The space between panels 21 and 24 contains suitable
insulating material 25.
As previously indicated, the outer shell 11 extends
across the top of the housing. As best shown in ~ig. 2, a
sheet metal panel 26 is spaced below the upper portion of shell
11 and has a flange 27 on its rear edge which is secured to the
shell and to panel 24. Insulation 28 fills the area above
panel 26 and below the top portion of shell 11. The forward
edge of the panel 26 has a flange 29 which is secured to a
brace 30 extending across the front of the oven at the upper
portion of the housing. Brace 30 is suitably secured to the
side walls and flange from panel 26 of the unit and to the
shell 11. The underside of panel 26 has a pair of integral
ribs 26a which intersect with one another in an "X" shaped
configuration to stiffen the panel and prevent it from warping
(and spaces heating element 60) or otherwise deforming when
heated to a high temperature.
The housing walls cooperate to provide a cooking
compartment 32 within the housing. Immediately above
compartment 32 is an air distribution chamber 33 which is
located below panel 26 and above a diffuser panel 34 mounted
within the oven. Panel 34 has a downwardly turned flange 35 on
its back edge which is suitably secured to panel 21. The front
portion of panel 34 is turned upwardly as indicated at 36. A
horizontal flange portion 37 is secured to panel 26 near the
front of the oven, while a downturned lip 38 is formed on the
front edge of panel 34. The upper surface of panel 34 which is
exposed to chamber 33 includes a pair of integral ribs 39 which
intersect in an "X" shaped configuration and which serve to
prevent thermally induced deformation of the diffuser panel.
Mounted in air distribution chamber 33 is a
centrifugal fan 40 having a central hub portion 41 and a
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plurality of spaced apart vanes ~2 which extend generally
radially from the hub por-tion 41 in a manner best shown in Fig.
3. Each vane 42 carries a vertical -fan blade 43 (Fig. 2) which
extends downwardly from the railing edge of the vane.
Fan 40 is driven by a conventional electric motor 44
contained within a motor housing 45 mounted on top of shell
ll. Motor 44 drives a vertical shaft 46 to which fan 40 is
secured by a set screw 47 threaded into hub portion 41. Shaft
46 carries another fan 48 which is located in the motor housing
45 and which operates to cool motor 44.
Motor housing 45 has a base 50 which is suitably
secured to the top portion of shell 11. The front face of
housing 45 is formed by a panel 15 having a pair of control
knobs 52 and 53 (See Fig. l). Knob 52 may control the
temperature setting of the oven, while the other knob 53 may be
a timer which acts to shut off the oven after a preselected
time period. These controls are conventional and form no part
of the invention.
With particular reference to Fig. 3, diffuser panel
34 has a circular intake opening 54 which is located off-center
on the diffuser panel near the back edge thereof. Fan 40 is
centered over intake opening 54 in order to draw air from oven
compartment 32 into air chamber 33. The central intake side of
f~n 40 is thus located adjacent opening 54, while the vanes 42
and fan blades 43 act to discharge the air generally radially
outwardly from the periphery of the fan.
A conventional filter element 55 is mounted
immediately below opening 54 to the underside of panel 34. The
filter element is preferably constructed of aluminum mesh
fibers which are able to extract grease and other undesirable
materials from the air which passes through the filter
element. As best shown in Fig. 1, filter 55 has a peripheral
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bead 56 which is supported on a pair of slide members or
flanges 57 extending from the underside of diffuser panel 34.
Filter element 55 is thus located directly below intake opening
54 such that any air passing through the in~ake opening is
~iltered. Element 55 may be removed for cleaning by simply
sliding it forwardly until bead 56 clears the flange 57~
A circular screen 5~ is mounted on top of diffuser
panel 34 in a position to cover intake opening 54. Screen 58
is located below fan 40 and above filter 55 and serves to
prevent fan 40 from being inadvertently contacted when the
ilter is removed.
Fan 40 circulates the air past an electrically
resistive heating element 60 which is mounted in chamber 33.
Heating element 60 is an elongate member having a heater wire
61 encased within a sheath 62, as best shown in Fig. 6. The
heating element is arranged in a serpentine configuration which
includes a pair of loops 63 and 64 on each side of fan 40 (See
~ig. 3). It is pointed out that the heating element is
arranged in a non-symmetrical manner with respect to intake
opening 54 and fan 40. Referring again to Fig. 6, heating
element 60 is mounted to panel 26 by a pair of brackets 65.
Each bracket 65 is secured to panel 26 by a pair of rivets 66,
and each bracket includes three spaced apart grooves 67 which
receive the straight portions of heating element 60 located
between the loops 63 and 64. In this fashion, heating element
60 is mounted in substantially the same horizontal plane which
contains the upper surface of fan 40. rrhe opposite sides of
heating element 60 are connected by an arcuate portion 60a
(Fig. 3).
Fig. 3 illustrates a plurality of elongated slots
which are formed in diffuser panel 34 to provide discharge
outlets directing heated air from chamber 33 back into cooking
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compartment 32. All of the discharge openings are located
outwardly o~ intake opening 54 and the heatiny element 60,
being arranged generally along the peripheral edges of panel
34. The openings vary from one another in their size and shape
and are arranged i~ a non-symmetrical pattern on the diffuser
panel 34 in order to effect uniform heating of compartment 32.
Numeral 70 designates a pair of the discharge
openings or slots which are formed near the back edge of panel
34. Another pair of openings 71 are located along the edge of
panel 34 which represents the right edge when viewed from the
front. Openings 71 are shorter than openings 70 and
considerably wider. A third opening 72 is formed along the
right edge of the diffuser panel near the forward end
thereof. Opening 72 has subs-tantially the same width as
openings 70 but is slightly shorter.
The left hand edge portion of panel 33 includes three
relatively small discharge openings 73 which are considerably
shorter than openings 70-72. As illustrated, openings 73 are
spaced apart in a non-uniform manner. Numeral 74 designates an
elongate slot which is formed along the front edge o panel 34
near the forward most opening 73. Slot 7~ is substantially the
same size and configuration as slot 72. A much smaller opening
75 is formed generally centrally along the forward edge of the
diffuser panel. Opening 75 has substantially the same size and
shape as the openings 73 located along the left edge of the
diffuser panel. The diffuser panel does not present a
discharge opening in the area between slots 72 and 75. The
discharge openings 70-75 are all in the form o slots which are
longer than they are wide.
An oven door 80 is mounted to the front of the
housing in order to open and close the front opening which
provides access to oven compartment 32. As best shown in Fig.
4, door 80 has a border or rim in the form of a "U" shaped
channel 81 which extends along both sldes of the door and -the
top and bottom edges thereof. Mounted within channel 81 at
each corner thereof is a spacer 82 having a "T" shaped cross
section. Each spacer 82 is held in place by a screw 83 which
secures it to channel 81. A pair of high temperature glass
panes 84 and 85 forming part of the oven door are held in
spaced apart relation by the spacers 82. The edges of panes 84
and 85 are held between the central portions of spacers 82 and
the corresponding inner or outer leg of the "U" shaped channel
81. Panes 84 and 85 are thus spaced apar~ from one another to
provide a gap 86 therebetween for thermally insulating the
door. One of the glass panes is preferably clear glass, while
the other is tinted. Consequently, the door exhibits the
advantages of tinted glass while permitting the con-tents of the
oven to be easily observed.
As shown in Figs. 1 and 4, the left panel 18 has a
pair of small slots 88 which receive flat hinges 89 extending
from the left edge of door 80. A pair of hinge brackets 90 are
mounted adjacent slots 88 to the surface of panel 18 which
faces to the inside of the oven wall. Each hinge 89 is
pivotally connected with the corresponding hinge bracket 90 by
a coupling element such as a screw 91. Door 80 is thus mounted
to the oven housing for pivotal opening and closing movement
about the vertical hinge axis provided by pivot couplings 91.
It is pointed out that the entirety of each brac~et 90 and the
majority of each hinge 89 is located within the side wall of
the oven. Accordingly, the small slots 88 provide the only
visible evidence of a hinge mechanism, and the physical
appearance of the oven is thereby enhanced.
Door 80 is held in the closed position by a bayonet
; type latch which is best illustrated in Fig. 5. The latch
includes a male latch mernber 92 which ex-tends through door 80
near the lower right hand corner thereof. Latch member 92 is
secured to the cloor by two pop rivets 93 and has a reduced head
portion 9~ projecting inwardly from the door. The head portion
94 is received by a female latch element g5 which engages latch
member 92 in a manner to releasably hold the door 80 in the
closed position covering the front of the oven. The female
latch element 95 is mounted to the right side wall of the oven
housing. A plastic knob 96 is mounted on the outer end of
latch member 92 by means of a key way in the knob which
receives an enlarged key portion 92a of the male latch
member. Latch member 92 thus serves both as the male portion
of the latch mechanism and as a means for mounting knob 96.
The knob has a flange 97 (Fig. 1) which prevents the fingers of
the user from possibly contacting a hot surface.
When door 80 is closed as shown in Fig. 2, it is in
firm contact with the lip 38 formed on the front edge of
diffuser panel 34. The lower edge of the door contacts a
similar lip portion 98 of floor panel 13. Side panels 18 have
similar lips 99 (Fig. 4) which contact the door. These lips
prevent the hot air within the oven compartment 32 from leaking
to any appreciable extent.
As best shown in Fig. 2, each side panel 18 has on
its inside surface a plurality of rack supports 100 for
supporting wire racks 101 which are adapted to recei~e the food
which is to be cooked within the oven. Each rack support 100
has near its center a recessed portion 102. Spaced above each
recess 102 is a stop 103 formed on the next higher rack support
at a location above the top surface of the rack support having
the recess. The uppermost stop 103 is simply formed on panel
18. The back edge of each rack 101 has an up turned wire 104
which contacts stop 103 if an attempt is made to pull the rack
~ f~ 5
straight out the front oE the oven. Conse~uently, each rack
101 must have its front end tilted upwardly in order to permit
wire 104 to pass stop 103. The wire racks thus cannot be
inadvertently pulled completely out oE the oven but must be
removed intentionally by tilting -them as they are pulled
forwardly.
In operation of the oven, the food which is to be
cooked is placed within cooking compartment 32 on one of the
wire racks 101. The temperature at which the food is to be
cooked is set on one of the knobs on panel 51, while the
cooking time is set on the other knob. The oven is preferably
equipped with a conventional thermostat which includes a
vertical capillary tube 106 shown in Fig. 2. When the
temperature sensed by the thermostat is above the tempera-ture
setting of the oven, heating element 60 is de-energized, and
they are also de-energized after elapse of the time which is
set on the timer knob of the oven.
Cooking of the food is accomplished by the combined
action of fan 40 and heating element 60. The fan draws air
from oven compartment 32 into air chamber 33 through the intake
opening 54 in diffuser plate 34. The air is then directed
outwardly from the periphery of fan 40 in a generally radial
direction. The air is thus directed in proximity to the
heating element 60 which heats the air prior to its discharge
back into compartment 32 through the discharge openlngs 70-
75. The heated air which is thereby directed into compartment
32 cooks the food which is contained therein.
It has been found experimentally that the non-
symmetrical arrangement of discharge outlets 73-75 and the
varying sizes and shapes thereof results in a substantially
even temperature distribution within the oven compartment 32.
It is thought that the effectiveness of the cooking discharge
f~B-~5
openings in achieving ~niform tleatiog of the cooking chamber is
due primarily to their relationship with the heating element
and the off-center intake opening 54, in cooperation with the
air circulation pattern within chamber 33. It is noted that
the larger holes are for the most part located where less heat
is generated, and the smaller holes are located where the air
is hottest. The air turbulence and circulation pattern which
results from the geometry of the oven, and the size and
arrangement of the discharge openings, causes the heat which
enters compartment 32 to be distributed uniformly throughout
the cooking compartment.
The diffuser panel 34 provides a partition between
chambers 32 and 33 and thus prevents the user from
inadvertently contacting the hottest portion of the oven in the
area of the heating element. At the same time, the diffuser
panel 34 distributes the heated air in the proper manner to the
cooking compartment in order to uniformly cook the food
therein. Any grease or other undesirable material present in
compartment 32 is filtered out of the circulating air by filter
element 35. The filter can be easily removed and periodically
cleaned.
It is thus evident that the present invention
provides an improved forced air convection oven which achieves
uniform heating of the cooking compartment and consequent
uniform cooking of the food contained therein. The
effectiveness of the cooking operation does not decrease with
increasing quantities of food in the cooking chamber. In
addition, the forced air circulation system cooks the food more
quickly than is accomplished in conventional ovens. Fan 40
does not draw in air from outside the oven but instead
circulates preheated air from within compartment 32 in order to
enhance the efficiency of the oven in comparison to units which
12
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utilize outside air.
From the fore~oin~, it will be seen that this
invention is one well adapted to attain all the ends and
objects hereinabove set forth together with other advantages
which are obvious and which are inherent to the structure.
It will be understood that certain features and
subcombinations are of utility and may be employed without
reference to other features and subcombinations. This is
contemplated by and is within the scope of the claimsO
Since many possible embodiments may be made of the
invention without departing from the scope thereof, it is to be
understood that all matter herein set forth or shown in the
accompanying drawings is to be interpreted as illustrative and
not in a limiting sense.
