U.S. patent application number 10/591074 was filed with the patent office on 2007-06-21 for conveyor oven.
Invention is credited to David McFadden.
Application Number | 20070137633 10/591074 |
Document ID | / |
Family ID | 37023221 |
Filed Date | 2007-06-21 |
United States Patent
Application |
20070137633 |
Kind Code |
A1 |
McFadden; David |
June 21, 2007 |
Conveyor oven
Abstract
An accelerated cooking or speed cooking conveyor oven with at
least one discrete cooking zone. The oven includes a first and a
second gas directing member configured to cause the gas from the
first gas directing member to collide with the gas fron the second
gas directing member upon the upper or lower surface of the food
product being conveyed.
Inventors: |
McFadden; David; (Lexington,
MA) |
Correspondence
Address: |
JOHN S. PRATT, ESQ;KILPATRICK STOCKTON, LLP
1100 PEACHTREE STREET
ATLANTA
GA
30309
US
|
Family ID: |
37023221 |
Appl. No.: |
10/591074 |
Filed: |
March 7, 2005 |
PCT Filed: |
March 7, 2005 |
PCT NO: |
PCT/US05/07261 |
371 Date: |
August 30, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60550578 |
Mar 5, 2004 |
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60551268 |
Mar 8, 2004 |
|
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60615888 |
Oct 5, 2004 |
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Current U.S.
Class: |
126/21A |
Current CPC
Class: |
H05B 6/6473 20130101;
H05B 6/782 20130101; H05B 6/60 20130101; H05B 6/6441 20130101; A21B
1/48 20130101; A21B 1/245 20130101 |
Class at
Publication: |
126/021.00A |
International
Class: |
F24C 15/32 20060101
F24C015/32 |
Claims
1. A conveyor oven for cooking a food product, comprising: a
cooking tunnel comprising: at least one cooking zone, each cooking
zone comprising: a housing defining a cooking chamber; a conduit
means for circulating gas to and from the cooking chamber; a flow
means for causing circulation of the gas; a means for heating the
gas; a first gas directing means disposed above the food product;
the first gas directing means being operably associated with the
conduit means; and a second gas directing means disposed above the
food product, the second gas directing means also being operably
associated with the conduit means; wherein the first and second gas
directing means are configured to cause the gas from the first gas
directing means to collide with the gas from the second gas
directing means upon or above the upper surface of the food
product; and a conveyor for conveying products through the cooking
zone.
2. A conveyor oven for cooking a food product, comprising: a
cooking tunnel, comprising: at least one cooking zone, each cooking
zone comprising: a housing defining a cooking chamber; a conduit
means for circulating gas to and from the cooking chamber; a flow
means for causing circulation of the gas; a means for heating the
gas; a first gas directing means disposed below the food product;
the first gas directing means being operably associated with the
conduit means; and a second gas directing means disposed below the
food product, the second gas directing means also being operably
associated with the conduit means; wherein the first and second gas
directing means are configured to cause the gas from the first gas
directing means to collide with the gas from the second gas
directing means upon or below the lower surface of the food
product; and a conveyor for conveying products through the cooking
zone.
3. The oven of claim 1 further comprising: a first lower gas
directing means disposed below the food product; the first lower
gas directing means being operably associated with the conduit
means; and a second lower gas directing means disposed below the
food product, the second lower gas directing means also being
operably associated with the conduit means; wherein the first and
second lower gas directing means are configured to cause the gas
from the first lower gas directing means to collide with the gas
from the second lower gas directing means upon or below the bottom
surface of the food product.
4. The oven of claim 1 wherein each cooking zone cooks the food
product independently of the other cooking zones.
5. The oven of claim 1 further comprising: a control means for
controlling the gas flow.
6. The oven of claim 1 wherein the gas exits the cooking chamber
via the top wall.
7. The oven of claim 1 further comprising: at least one odor
filter.
8. The oven of claim 1 further comprising: a damper means for
adjusting the amount of said gas delivered via said conduit means
to said first, second, first lower and second lower gas directing
means.
9. The oven of claim 1 wherein the flow means is a blower
motor.
10. The oven of claim 9 wherein the blower motor runs at variable
speeds.
11. The oven of claim 1 wherein the thermal means is a electric
resistance heater.
12. The oven of claim 1 wherein the control means is a toggle
switch.
13. The oven of claim 12 wherein the toggle switch controls the
flow means.
14. The oven of claim 5 wherein the control means is a rotary
switch.
15. The oven of claim 14 wherein the rotary switch controls the
flow means.
16. The oven of claim 1 further comprising: an electromagnetic
source.
17. The oven of claim 16 wherein the control means controls the
electromagnetic source, the damper means, the flow means, the
thermal means, or combinations thereof.
18. The oven of claim 16 wherein the control means is comprised of
toggle switches to control the electromagnetic source, the damper
means, the flow means, the thermal means, or combinations
thereof.
19. The oven of claim 16 wherein the control means is comprised of
rotary switches to control the electromagnetic source, the damper
means, the flow means, the thermal means, or combinations
thereof.
20. The oven of claim 16 further comprising: a control panel for
controlling the operation of the electromagnetic source, the damper
means, the flow means, the thermal means, or combinations
thereof.
21. An oven as defined in claim 1 further comprising: an egress
opening to allow the gas to exit the cooking chamber and a catalyst
located within said egress opening.
22. The oven of claim 21 wherein said egress opening is located in
a top wall of the cooking chamber.
23. The oven of claim 21 wherein said egress opening is located in
a side wall of the cooking chamber.
24. The oven of claim 21 wherein said egress opening is located in
a back wall of the cooking chamber.
25. The oven of claim 21 wherein said egress opening is located in
a bottom wall of a cooking chamber.
26. The oven of claim 1 wherein the first gas directing means and
the second gas directing means are located within a top wall.
27. The oven of claim 1 wherein the first gas directing means and
the second gas directing means are located within the right and
left side walls.
28. The oven of claim 1 wherein the first gas directing means and
the second gas directing means are located at the intersection of
side walls and a top wall.
29. The oven of claim 1 wherein the first gas directing means and
the second gas directing means are located within a back wall.
30. The oven of claim 2 wherein the first lower gas directing means
and the second lower gas directing means are located within a
bottom wall.
31. The oven of claim 2 wherein the first lower gas directing means
and the second lower gas directing means are located within the
right and left side walls.
32. The oven of claim 2 wherein the first lower gas directing means
and the second lower gas directing means are located at the
intersection of the side walls and a bottom wall.
33. The oven of claim 2 wherein the first lower gas directing means
and the second lower gas directing means are located within a back
wall.
34. The oven of claim 1 wherein the thermal means is a heater
powered by gaseous fuel.
35. The oven of claim 34 wherein the gaseous fuel is propane.
36. The oven of claim 34 wherein the gaseous fuel is natural
gas.
37. The oven of claim 1 wherein said oven is a speed cooking
oven.
38. The oven of claim 1 wherein said oven is a conventional cooking
oven.
39. The oven of claim 1 wherein said oven is an accelerated cooking
oven.
40. The oven of claim 1 wherein said oven is a recycling oven.
41. The oven of claim 1 further comprising: at least two additional
gas directing means for direction on at least one further food
product.
42. The oven of claim 1 further comprising: an ingress door
disposed at one end of the cooking tunnel; an egress door disposed
at the other end of the cooking tunnel; a plurality of sealing
means carried by the conveyor for providing a seal between the
ingress door and the cooking tunnel and between the egress door and
the cooking tunnel.
43. The oven of claim 7 wherein the odor filter is a catalytic odor
filter.
44. The oven of claim 1 having a bleed gas flow system further
comprising: a gas bleed chamber, and an odor filter within the gas
bleed chamber.
45. The oven of claim 44 wherein the odor filter causes catalytic
destruction of cooking by-products.
46. The oven of claim 45 further comprising a pre-heater to heat
the bleed gas flow prior to the gas entering the catalytic odor
filter.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S.
Provisional Application No. 60/550,578, filed Mar. 5, 2004,
entitled "SPEED COOKING CONVEYOR OVEN"; the benefit of U.S.
Provisional Application No. 60/551,268,filed Mar. 8, 2004, entitled
"ANTENNA COVER; and the benefit of U.S. Provisional Application No.
60/615,888, filed Oct. 5, 2004, entitled "CATALYST FOR SPEED
COOKING OVEN".
[0002] The present application is a continuation-in-part of U.S.
application Ser. No. 10/614,479, filed Jul. 7, 2003, entitled
"SPEED COOKING OVEN", currently pending, which claims the benefit
of U.S. Provisional Application No. 60/394,216, entitled "RAPID
COOKING OVEN", filed Jul. 5, 2002; a continuation-in-part of U.S.
application Ser. No. 10/614,268,filed Jul. 7, 2003, entitled "MULTI
RACK SPEED COOKING OVEN", currently pending, which claims the
benefit of U.S. Provisional Application No. 60/394,216, entitled
"RAPID COOKING OVEN", filed Jul. 5, 2002; a continuation-in-part of
U.S. application Ser. No. 10/614,710, filed Jul. 7, 2003, entitled
"SPEED COOKING OVEN WITH GAS FLOW CONTROL", currently pending,
which claims the benefit of U.S. Provisional Application No.
60/394,216, entitled "RAPID COOKING OVEN", filed Jul. 5, 2002; a
continuation-in-part of U.S. application Ser. No. 10/614,532, filed
Jul. 7, 2003, entitled "SPEED COOKING OVEN", currently pending,
which claims the benefit of U.S. Provisional Application No.
60/394,216, entitled "RAPID COOKING OVEN", filed Jul. 5, 2002.
[0003] The present application contains technical disclosure in
common with PCT/US03/021225, entitled "SPEED COOKING OVEN" filed
Jul. 5, 2003, currently pending, which claims the benefit of U.S.
Provisional Application No. 60/394,216, entitled "RAPID COOKING
OVEN", filed Jul. 5, 2002; and contains technical disclosure in
common with PCT/US04/035252 entitled "SPEED COOKING OVEN WITH
SLOTTED MICROWAVE ANTENNA", filed Oct. 21, 2004, which claims the
benefit of U.S. Provisional Application No. 60/513,110, filed Oct.
21, 2003,entitled "SLOTTED ANTENNA", which also claims the benefit
of U.S. Provisional Application No. 60/513,111, filed Oct. 23,
2003, entitled "MICROWAVE ANTENNA COVER FOR RAPID COOKING OVEN",
which also claims the benefit of U.S. Application No. 60/614,877,
filed Sep. 30, 2004, entitled "SLOT ANTENNA". Each of these
applications are incorporated herein by reference as if fully set
forth.
BACKGROUND
[0004] The typical cook time for a food product such as a fresh
medium size pizza (12 to 14 inch) through a conventional conveyor
oven is approximately 7 minutes, and 15 minutes through a deck
style oven. The conveyor oven reduces cooking time as compared to
the deck oven and also simplifies the cooking procedure because the
food product is automatically loaded into and unloaded from the
cooking tunnel.
[0005] Conveyor ovens typically utilize a continuous open link
conveyor belt to transport food products through a heated cooking
tunnel which has openings at each end of the oven through which the
conveyor belt sufficiently extends in order for the operator to
start incoming food product on one end, and retrieve the finished
cook product from the other. These conveyor oven tunnels are
generally open at each end and in instances wherein microwave
energy is used, long entrance and exit tunnels are required in
order to reduce the amount of microwave energy exiting the tunnel
ends. Pizza output capability for such a large conveyor oven is
generally approximately 100 to 120 medium pizzas per hour.
[0006] Although cooking speed is important, food quality is also
very important. Quality is generally highest when the food product
is cooked and presented to the consumer as soon as possible (cooked
to order). As such, food service operators must provide fast
service in addition to a high quality food product and pre-cooking
and holding food is therefore not desirable because the quality is
substantially less than that of a cooked to order food product.
[0007] A conveyor oven virtually guarantees that a cooked food
product will be removed from the oven at the proper time, but
conveyor ovens have not generally been compatible with some type of
food service operations such as: quick service restaurant (QSR);
consumer operated ovens where the consumer is a retail customer at
a retail location such as a convenience store; or retail
foodservice locations with no room for a large conveyor oven, to
name a few.
SUMMARY
[0008] It has now been found that the above objects are obtained in
a conveyor oven with at least one cooking zone and employing gas
flow to cook, or re-thermalize a food product. The gas flow to the
food product is such that conflicting and colliding gas flows
produce high heat transfer at the food product surface. Our
conveyor oven may also utilize microwave energy, or other means
such as radio frequency, induction and other thermal means, to
further heat the food product. Microwave producing magnetrons are
used with side wall mounted microwave waveguides employing the use
of slotted antenna, although it is not necessary that the microwave
system launches from the oven cavity side walls and indeed
launching microwaves from other oven cavity surfaces may be
employed. Our conveyor oven may operate as a conventional speed, an
accelerated speed or a speed cooking conveyor oven. the speed
cooking conveyor oven is described herein as an exemplary
embodiment or version. The speed cooking conveyor oven has a
cooking tunnel with one or more discrete cooking zones and conveyor
transport means that moves or indexes food product through the
cooking tunnel with product loading and unloading areas located
prior to and after the cooking tunnel. The conveyor loading area
for food product is sized such that the available area for food
product is smaller than the area of each cook zone of the cooking
tunnel. Gas flow and microwave energies (when microwaves are used)
are distributed to the food product in a manner that produces
uniform cooking and heating and a typical cook zone temperature
range may be in the approximately 375.degree. F. (190 degrees
Celsius "C.") to approximately 500.degree. F. (260.degree. C.)
range, although cook zone temperatures below 375.degree. F.
(190.degree. C.) and above 500.degree. F. (260.degree. C.) may be
utilized. Gas flow throughout the cooking tunnel is common to all
cook zones and a common heating means provides hot gas for the
cooking tunnel. Cooking controls permits a wide variety of food
products to be run sequentially through the cooking tunnel with
each food product having a unique cooking profile, or recipe, that
will be executed in a sequential format as the food product moves,
or indexes, through the cooking zones. The indexing conveyor of the
exemplary embodiment operates at a fixed rate, that is, each cook
zone holds food product for the same length of time, but the
indexing time may vary or may be altered or otherwise set according
to the needs of the operator.
[0009] An optimum speed cooking conveyor oven will maintain the
convenience of a conventional conveyor oven but cook a fresh food
product such as a medium pizza to a high quality level in less than
3 minutes, thereby representing an approximately fifty percent
decrease in cooking time over the conventional conveyor oven. The
more than double increase in production rate of our invention over
the conventional conveyor oven represents a significant decrease in
cooking time and may allow a foodservice operation to increase the
number of customer served by: adding a drive-through operation;
increasing table service turn rates; implementing a consumer
operated conveyor oven, or enabling a quick walk-in/take out
function, to name a few. For operations that currently require
multiple ovens to meet customer demand, the significantly reduced
cook times of our speed cooking conveyor oven permits the same
collective food throughput with fewer ovens.
[0010] In addition to such items as pizza, our invention is capable
of warming and cooking a wide variety of foods such as seafood,
Mexican food, hot dogs, sausage, sandwiches, casseroles, biscuits,
muffins, french fries, fresh and frozen appetizers, fresh proteins,
pies, bread products, and indeed, any food product that can be
cooked in a conventional oven. Generally, conventional conveyor
ovens do not have a tall cooking tunnel but because different food
products are of varying volumes, heights and size profiles, a tall
cooking tunnel is desirable for cooking various food products and
the cooking tunnel of our invention allows for such cooking of
various food products. It is also desirable to keep energy
consumption as low as possible. In order to accomplish reduced
energy costs, our invention utilizes recycling gas flow and reduces
heat loss from the tunnel ends. Not only is energy savings a
benefit, reduction of heat loss from the tunnel ends improves the
effective energy transfer to the food product. Our speed cooking
conveyor oven is also simple and safe to operate, easy to clean and
maintain, easy to service and low cost to manufacture.
[0011] Accordingly, it is an object of the present invention to
provide a conveyor oven capable of cooking and warming a broad
variety of food products with varying size and volume profiles
either at conventional or speed cooking times.
[0012] A further object is to provide such a conveyor oven that is
energy efficient, simple and safe to operate, simple and easy to
clean, easily serviceable and has a low manufacturing cost.
[0013] Still another object is to provide such a conveyor oven that
is capable of cooking high quality food product within metal pans,
pots, sheet pans and other metal cooking devices commonly found in
residential, commercial and vending venues.
[0014] It is a further object to provide such an oven with a
microwave distribution system which is more cost effective to
manufacture and easy to clean and maintain.
[0015] Yet another object is to provide such a microwave
distribution system that is reliable due to improvements and
simplifications.
[0016] Still another object is to provide such an oven that can be
easily and quickly programmed by an operator to cook various food
products with the touch of a button or such an oven that
automatically inputs cooking recipes into a controller without
human intervention.
[0017] Additional objects, features and advantages of the present
invention will become readily apparent from the following detailed
description of the exemplary embodiment thereof, when taken in
conjunction with the drawings wherein like reference numerals refer
to corresponding parts in the several views.
DRAWINGS
[0018] The novel features believed characteristic of the invention
are set forth in the appended claims. The invention itself,
however, as well as a preferred mode of use, further objectives and
advantages thereof, will best be understood by reference to the
following detailed description of an illustrative embodiment when
read in conjunction with the accompanying drawings, wherein:
[0019] FIG. 1 is a front view of the conveyor oven of the present
invention illustrating gas flow supply;
[0020] FIG. 2 is a front view of the conveyor oven of the present
invention illustrating gas flow return;
[0021] FIG. 3 is a top view of the conveyor oven of the present
invention;
[0022] FIG. 4 is top view of the conveyor oven of the present
invention illustrating product location relative to cook zones;
[0023] FIG. 5 is an end view of the cooking tunnel of the conveyor
oven of the present invention;
[0024] FIG. 6 schematically represents gas flow nodes for the
conveyor oven of the present invention;
[0025] FIG. 7 is a front view of the ingress door microwave
containment mechanism of the conveyor oven of the present
invention;
[0026] FIG. 8 is a front view of the front side section
illustrating a microwave slot antenna;
[0027] FIG. 9 is an exploded view of the microwave slot antenna of
FIG. 8.
[0028] FIG. 10 is an end view of the front side of the conveyor
oven illustrating gas flow deflecting means;
[0029] FIG. 11 is an end view of the back side of the conveyor oven
illustrating gas flow deflecting means;
[0030] FIG. 12 illustrates the bleed gas flow of the conveyor oven
of the present invention.
DESCRIPTION
[0031] The oven of the exemplary embodiment is shown as a three
cook zone speed cooking commercial conveyor cooking appliance
wherein each cook zone is shown to be manufactured in the same
manner, although it is not necessary that each cook zone be the
same and indeed in some instances it may be desirable that one or
more cook zones be made differently. Our conveyor oven may be built
in other embodiments because it is scalable up or scalable down.
The term "scalable" herein means that additional larger or smaller
versions may be developed, and each embodiment or version may have
different size characteristics and utilize different voltages of
electricity; various forms of electric resistance heating means, or
utilize other thermal sources such as natural gas, propane or other
thermal means to heat the gas.
[0032] As used herein, the terms "magnetron", "magnetron tube" and
"tube" have the same meaning; the terms "slot" "slots" and
"antenna" have the same meaning; the term "commercial" includes,
but is not limited to the commercial food service industry,
restaurants, fast food establishments, speed service restaurants,
convenience stores (to list a few) and other mass feeding
establishments; the term "residential" refers, generally speaking,
to residential applications (home use), although the term is not
limited to residences only, but refers to non-commercial
applications for the speed cooking oven and our speed cook conveyor
oven is not limited to commercial uses only, and is equally
applicable for vending, residential and other cooking uses; the
terms "oven zone" and "oven cavity" have the same meaning and the
term "gas" refers to any fluid mixture, including air, nitrogen and
other mixtures that may be used for cooking and applicant intends
to encompass within the language any gas or gas mixture existing or
developed in the future that performs the same function. The term
"cook zone" refers to a separate and discrete cooking area within
the oven cooking tunnel and the term "cooking tunnel" refers to
that area of the conveyor oven wherein cooking takes place. For
example, in a one cook zone speed cooking conveyor oven, there will
exist one cook zone and one cooking tunnel. In a two cook zone
speed cooking conveyor oven there will exist two cook zones but
only one cooking tunnel, and so on. The means for moving the food
product through the speed cooking conveyor oven is referred to
herein as the "conveyor transport means". The terms "dwell time"
and "cook time" have the same meaning. and the terms "conventional
cooking" and "conventional means", have the same meaning and refer
to cooking at the quality level and at the speed that is currently
widely utilized. By way of example, the "conventional cooking time"
for a fresh 10-12 inch pizza through a conventional oven is
approximately 7 minutes (e.g. conventional cooking time). The term
"cooking by-products" refers to smoke, grease, vapors, small
aerodynamic grease particles, odors, and other products caused by
the cooking process and the term "odor filter" does not refer
exclusively to filtering of odors, but instead refers generally to
filtering, reduction of, removal of or catalytic destruction of
by-products of the cooking process.
[0033] As used herein, the term "rapid cooking" and "speed cooking"
have the same meaning and refer to cooking at five to ten times
faster, and in some instances more than 10 times faster than
conventional cooking. The term "accelerated cooking" has the
meaning of cooking at speeds faster than conventional cooking but
not as fast as speed cooking.
[0034] The exemplary embodiment employs the use of an indexing
conveyor transport means wherein the operating speed or feed rate
is fixed, meaning that each cook -zone holds food product for the
same length of time. The dwell time may be varied or fixed, may be
altered either manually or by controller 334 (see FIG. 3), and is
not limited. The indexing motion of the conveyor transport means is
a cycle consisting of a traverse to move food product to the next
cook zone followed by a dwell or cooking period wherein the food
product is stopped within a cook zone. This indexing motion insures
that the energy delivered to the food product may be individualized
for each food product. Control of the energy applied to the food
product is important particularly in those instances wherein the
conveyor oven is to cook a variety of food products successively
and the cooking profile, or cook recipe must be adjusted as the
different food products enter the oven tunnel. The conveyor oven
may operate as a conventional, accelerated or speed cooking
conveyor oven.
[0035] Appliance 301 includes cook zones 380, 381 and 382 within
cooking tunnel 394, FIG. 4. The cook zones may be spaced together
or a distance apart, depending upon the particular conveyor oven
that is desired. Each cook zone is generally defined by an oven
cavity 302, FIG. 5, a top wall 303, a bottom wall 304, a front side
wall 305 and a back side wall 306. Front wall 305 is comprised of
top gas discharge plate 323a, microwave launcher 320a (when
microwaves are utilized) and lower gas discharge plate 327a. Back
side wall 306 is comprised of top gas discharge plate 323b,
microwave launcher 320b (when microwaves are used) and lower gas
discharge plate 327b, FIG. 5. In those instances wherein microwave
energy is not utilized in the conveyor oven, front and back side
walls 305 and 306 may be comprised of a sheet of metal instead of
front of waveguides 320a and 320b. Oven cooking tunnel 394 has
associated therewith a movable ingress door 398 and a movable
egress door 397, FIG. 1. Food product 310, FIG. 4 is placed on
conveyor transport means 399 for indexed transport through oven
tunnel 394. As previously described, indexed motion is not required
and a continuous transport means may be utilized in those instances
wherein microwave energy is used and means other than ingress and
egress doors are employed in order to contain the microwave energy
within cooking tunnel 394. Although doors 397, 398 are shown as
movable vertically relative to the conveyor transport means, other
door opening and closing means may be employed; such as side-hinged
doors, top hinged doors or doors utilizing other attachment means,
and applicant does not intend to be limited but rather intends to
encompass within the language any structure presently existing or
developed in the future that performs the same function as doors
397, 398.
[0036] The conveyor oven is comprised of two independent gas
transfer systems, described herein as a front gas transfer system
and a back gas transfer system, wherein the front gas transfer
system 393a delivers gas to and from the front side of cook zones
380, 381, 382, FIG. 3, and back gas transfer system 393b delivers
gas to and from the back side of the cook zones 380, 381, 382. Cook
zones 380, 381, 382 may also have associated therewith vent tube
371, FIG. 5, which allows for the passage of vent gas from any one,
or all, of cook zones 380, 381, 382 to atmosphere. Affixed within
vent tube 371 may be vent odor filter 372, which provides for the
removal of cooking by-products. Vent odor filter 372 may be made to
be removable for cleaning or replacement and various materials,
including catalytic materials, may be utilized to accomplish odor
removal. In some instances, varying efficiencies of said materials
may also be employed in order to allow various amounts of odors to
escape the oven cavity.
[0037] Referring again to FIG. 3, gas is transferred to cook zones
380, 381, 382 via front gas transfer conduit 393a extending from
gas flow means 316a to first cook zone 380, then continuing to
second cook zone 381 and terminating with third cook zone 382,
FIGS. 1, 3. In fluid connection with front conduit means 393a are
gas flow nodes 390a, 391a, 392, FIG. 6, which allow for the passage
of gas from gas transfer conduit 393a to top gas transfer section
317a, FIG. 5, of each cook zone 380, 381 and 382. In fluid
connection with top gas transfer section 317a is top gas egress
opening 312, FIG. 2, within each cook zone, which is open to, and
in fluid connection with oven zone 302 through top wall 303. Top
gas egress opening 312 is substantially rectangular, although other
geometries may be employed, and is centrally located within each
oven top wall 303 and provides for the passage of gas from oven
zone 302 into return conduit means 389, FIG. 1 which returns gas
from oven zone cook zones 380, 381, 382 to gas flow means 316a as
gases are removed from oven zone 302 through top egress gas egress
opening 312. Located within each top gas egress opening 312 may be
grease extractor 313, FIG. 2. As gas is drawn through top gas
egress opening 312 of each oven zone, the gas passes across grease
extractor 313, which removes the larger grease particles. By
extracting the larger grease particles managing grease build-up in
the down stream conduits and heater area is simplified. It may be
desirable for each cook zone to utilize grease extractor 313, or
alternatively no grease extractor, or still further additional
grease extractors may be placed throughout the gas flow path.
[0038] During normal cooking it may be desirable for one food
product to be cooked after another different type of food product
with successive cycles continuing. For example a food product such
as shrimp may be cooked first, followed by a baked product or
pastry. Without appropriate filtration, the cooking by-products
will contaminate the baked product, producing an undesirable taste
and odor in the pastry. Although grease extractors 313 may be
utilized, further gas filtration may be desirable and odor filters
343, FIG. 2 may be placed within any or all cook zones or within
the oven tunnel and may be placed upstream of blowers 316a, 316b to
be discussed further herein, and may be made of various materials
including catalyst materials such as a corrugated foil coated with
catalyst, or catalyst coated screens. The catalyst acts to combust
(oxidize) the cooking by-products. Such catalyst materials may also
include, but is not limited to: activated charcoal, zeolite or
ultra violet wavelight light. It is beneficial that the odor
filters be comprised of a material, or materials, that effectively
scrubs, or cleans the gas flow with a minimal amount of
interference with the gas flow velocities and it is beneficial that
the odor filters be easily removed, easily cleaned and inexpensive
for the operator to replace. The most efficient utilization of the
spent hot gas from cook cavity 302 is by re-circulation of the gas
through the oven tunnel many times during a cooking cycle. In some
uses, it may be desirable to utilize additional odor filters, which
may be placed anywhere within the gas flow path. Depending upon the
various levels of cooking by-product control that may be desired
depending upon the food products to be cooked, the particular use
of the oven, or the requirements of regulatory agencies, or other
factors, in order to minimize cooking by-products within each oven
zone, the oven tunnel or the gas flow supply and return conduits
may therefore include one odor filter per appliance 301, "n" number
of odor filters as determined by "n" cook zones, or more than "n"
number of odor filters.
[0039] As used herein the term "upstream" refers to a location
within the gas flow path that comes before gas flow means 316a and
316b. For example, gas that is supplied to gas flow means 316a,
316b is upstream of gas flow means 316a, 316b and gas that is
discharged from gas flow means 316a, 316b is downstream of said gas
flow means. The exemplary embodiment illustrates gas flow means as
blower wheels 316a, 316b, although our invention may utilize a
single gas flow device, such as a single blower wheel and applicant
intends to encompass within the language any structure presently
existing or developed in the future that performs the same function
as 316a, 316b. Blower wheels 316a, 316b act much like centrifugal
separators that will separate and coalesce the small grease
particles in the blower scroll area and discharge larger particles
into the supply area.
[0040] In an alternate embodiment, a portion of the gas flow
leaving gas flow means 316a, 316b is diverted to the inlet side of
gas bleed chamber 365a, 365b with odor filters 340 located within
bleed chambers. The portion of gas flow diverted to said bleed
chamber is referred to herein as the "bleed gas flow." The bleed
gas flow passes through odor filter 340, FIG. 12 shown as a
catalytic converter, where a portion of the cooking by-products is
oxidized. Cleaner gas leaving odor filter 340 is either
reintroduced into the gas flow stream or is vented to atmosphere
via vent tube 371. Odor filter 340 will remove the desired amount
of grease during a single pass as the small bleed gas flow will
continually remove grease generated during cooking. Indeed, in some
embodiments it may be desirable for the odor filter to remove all,
or as much cooking by-product as possible. Varying destruction
efficiencies of odor filter 340 will produce varying results and in
those instances wherein odor filter 340 is of the catalytic type,
destruction efficiencies of greater than 50% have shown to produce
acceptable results. The bleed gas flow is configured as an internal
cleaning gas loop operating separate from the main gas flow to oven
tunnel 394. In those instances wherein odor filter 340 is a high
efficiency catalytic type filter for high cooking by-product
destruction efficiencies, a large pressure drop may occur across
odor filter 340. Space velocities for the catalytic converter range
are typically in the range between approximately 60,000/hr to
120,000/hr depending on the catalyst material utilized, the amount
of cooking by-product loading in the gas stream and odor filter 340
inlet ambient temperature. Unlike the placement of odor filter 343
in the main gas flow which results in a significant pressure drop
on the entire re-circulating gas flow, the use of bleed gas
catalytic type filters, or other odor filters, does not
significantly reduce gas flow system pressure to oven tunnel 394.
The small bleed gas flow utilizes nearly the entire pressure
capability of the gas flow means through the gas bleed system,
thereby permitting the use of catalytic materials required for a
high destruction efficiency, based on one pass through odor filter
340. Additionally, the small bleed gas odor filters 340 are easily
installed, can be placed in convenient locations and readily
accessible. Bleed gas flows are a fraction of the main gas flow to
the oven tunnel, therefore significant inlet gas temperature
preheat may be achieved. Placing small gas pre-heaters 341a, 341b,
FIG. 12 prior to odor filters 340 within the bleed gas flow system
may additionally provide substantial improvement in the destruction
efficiency of odor filter 340. Pre-heaters 341a, 341b are capable
of increasing the gas inlet temperature by greater than 100.degree.
F. (37.78.degree. C.) and this temperature increase in the bleed
gas to odor filter 340 makes it possible to achieve the desired
destruction efficiency with less catalyst material. In some
instances a main gas flow odor and cooking by-product clean-up
system may have difficulty cleaning the gas when oven set point is
under approximately 425.degree. F. (218.3.degree. C.). Pre-heaters
341 are capable of producing cooking by-product control with oven
tunnel temperatures below 350.degree. F. (176.67.degree. C.).
Additional appliance flexibility is achieved by simultaneously
permitting lower oven cook temperature setting while providing
grease control.
[0041] The bleed gas flow is approximately 10% of the total gas
flow, blowers 316a, 316b, and pre-heaters 341a, 341b would each
provide approximately 600 watts of heat for a 100.degree. F.
(37.78.degree. C.) rise in gas inlet temperature. The combined 1200
watts of heating is less than one third of the total heat required
for each oven zone of conveyor oven and is very close to the heat
needed to satisfy standby losses of the oven (i.e., heat loss due
to conduction, radiation, vent losses to ambient). As such, the
pre-heaters can be the primary gas heaters with the larger (for
this example 3000 W) main gas heater used to satisfy cooking
needs.
[0042] As previously described, in fluid connection with, and
located within return conduit means 389 is a front gas flow means,
illustrated as front blower wheel 316a, FIGS. 1,5. Our invention
may utilize variable speed blower motors and variable speed blower
motor controllers, but there is no requirement for their use and
indeed the conveyor oven of the present invention may avoid the
problems and complexity of variable speed blower motors by
maintaining a constant gas flow, or alternatively, a substantially
constant gas glow rate through the oven zones, oven tunnel and gas
transfer and gas delivery systems. The gas flow may be very
aggressive, or less aggressive, depending upon the cooking
requirements for each food product and one means to achieve gas
flow modulation is by use of a gas pumping means such as a blower
motor, blower wheel combination, utilizing a controller or a multi
speed switch that allows for the switching of the blower motor
speed in pre-determined fixed increments. Other gas flow means may
be utilized to accelerate the gas flow, and applicant intends to
encompass within the language any structure presently existing or
developed in the future that performs the same function as 316a,
390a, 391a and 316b, 390b and 391b, to be discussed further herein.
Connected to front blower wheel 316a is blower motor shaft 390a,
which is direct drive with electric motor 391a, FIG. 5. Other means
may be employed for coupling blower wheel 316a to electric motor
391a, such as belt drive and the drive means is not limited to
direct drive and applicant intends to encompass within the language
any structure presently existing or developed in the future that
performs the same function. Blower wheel 316a takes gas from return
conduit means 389 and delivers the gas via conduit means 393a to
node sections 390a, 391a, 392a, FIG. 6. Within node sections 390a,
391a, 392a are gas flow control means 388a, FIG. 1, which allow for
the passage of gas from conduit means 393a to gas transfer section
317a of each oven zone. Gas flow control means 388a may allow for
the passage of varying quantities of gas, or no gas, to transfer
section 317a of each cook zone and are shown as valves 388a,
although other means may be employed in order to allow, limit or
restrict the gas flow to each oven zone 380, 381, 382 by nodes
392a, 391a, 390a and applicant intends to encompass within the
language any structure presently existing or developed in the
future that performs the same function as valves 388a.
[0043] Top front gas transfer section 317a, FIG. 5, is in fluid
connection with a lower front gas transfer section 318a via a front
vertical gas transfer section 319a. Front vertical gas transfer
section 319a is bounded by front side wall 366 and a front
microwave waveguide section 320a, when microwaves are used. When
microwaves are not used, waveguide launcher 320a may be replaced by
metal. As can be seen in FIG. 5, as gas is supplied into top front
gas transfer section 317a, the gas is discharged through a top
front gas discharge plate 323a into oven zone 302 via apertures
300a and onto the front top and front side portion of food product
310. Apertures 300a may be slotted, regularly formed or irregularly
formed apertures and are illustrated herein as nozzles 300a and
300b, 329a, 329b, FIG. 5, and applicant intends to encompass within
the language any structure presently existing or developed in the
future that performs the same function as 300a, 329a and 300b and
329b, discussed further herein. Gas that has not been discharged
through top front gas discharge plate 323a flows to lower front gas
transfer section 318a via vertical transfer section 319a. Gas that
is distributed to lower front gas transfer section 318a may be
re-heated, if desired, by a lower front heating means 303a, FIG. 5,
before said gas passes through slotted or perforated lower front
gas discharge plate 327a via apertures 329a, for discharge onto the
front bottom and front side portions of food product 310 in oven
zone 302. Lower front heating means 303a may be present in some
embodiments and not present in others depending upon the particular
requirements for the speed cooking conveyor oven. Although lower
front heating means 303a is shown as an electric open coil heater,
other means to heat the gas may be utilized such as other types of
electric heating means, electric resistance elements, natural gas,
propane or other heating means and applicant intends to encompass
within the language any structure presently existing or developed
in the future that performs the same function as 303a and 303b to
be discussed further herein. Apertures 300a and 329a are sized for
a low pressure drop, while providing and maintaining sufficient gas
velocities in the range of approximately 2000 ft/minute (609.6
meters/minute) to approximately 6000 ft/minute (1828.80
meters/minute) to properly cook the food product as described
herein. In some instances, velocities below 2000 ft/minute (609.6
meters/minute) or above 6000 ft/minute (1828.80 meters/minute) may
also be utilized, depending upon the particular food product to be
cooked, or a particular cooking recipe that the controller is
executing, to be discussed further herein, and applicant does not
intend to limit the invention to gas velocities within a particular
range. Apertures 300a are sized such that the majority of the gas
is supplied from top front gas discharge plate 323a. The resulting
imbalance of gas flows between the top front gas discharge plate
323a and lower front gas discharge plate 327a is desirable because
the top flows must aggressively remove moisture produced and
escaping from the top and top side surfaces of the food product
310. The gas flow imbalance also serves to heat, brown and/or heat
and brown the food product 310.
[0044] Referring again to FIG. 3, gas is transferred to the back of
cook zones 380, 381, 382 via a back gas transfer conduit 393b, FIG.
3, extending from gas flow means 316b to first cook zone 380, then
continuing to second cook zone 381 and terminating with third cook
zone 382, FIGS. 1,3, in the same manner as previously described for
front gas transfer section 393a. In fluid connection with back
conduit means 393b are gas flow nodes 390b, 391b, 392b, FIG. 6,
which allow for the passage of gas from gas transfer conduit 393b
to top gas transfer sections 317b, FIG. 4, of each cook zone 380,
381 and 382. In fluid connection with top gas transfer section 317b
is the previously described top gas egress opening 312, which is in
fluid connection with return conduit means 389b. Return conduit
means 389b is in fluid connection with a back gas flow means,
illustrated as back blower wheel 316b, FIG. 3. As with blower wheel
316a, other devices may be utilized for gas flow means 316b to
accelerate the gas flow, and applicant intends to encompass within
the language any structure presently existing or developed in the
future that performs the same function. Connected to back blower
wheel 316b is blower motor shaft 390b, which is direct drive with
electric motor 391b, and as with electric motor 391a other means
may be employed for coupling blower wheel 316b to electric motor
391b. Blower wheel 316b takes gas from oven zone 302 via common
return conduit means 389 and delivers the gas via conduit means
393b to node sections 390b, 391b, 392b, FIG. 6. Within node
sections 390b, 391b, 392b are gas flow control means 388b, FIG. 5,
which allow for the passage of gas from conduit means 393b to
transfer section 317b of each oven zone. As with gas flow control
means 388a, flow control means 388b, FIG. 5, may allow for the
passage of no gas, or varying quantities of gas to transfer section
317b and are shown as valves 388b although other means may be
employed in order to limit or restrict the gas flow to each oven
zone 380, 381, 382 and applicant intends to encompass within the
language any structure presently existing or developed in the
future that performs the same function as valves 388b.
[0045] Top back gas transfer section 317b, FIG. 5, is in fluid
connection with a lower back gas transfer section 318b via a back
vertical gas transfer section 319b. Back vertical gas transfer
section 319b is bounded by back side wall 367 and back microwave
waveguide section 320b. As can be seen in FIG. 5, as gas is
supplied into top back gas transfer section 317b, the gas is
discharged through a top back gas discharge plate 323b into oven
zone 302 via apertures 300b and onto the back top and back side
portion of food product 310. Apertures 300b may be slotted,
regularly formed or irregularly formed apertures and are
illustrated herein as nozzles 300b and 329b, FIG. 5, and applicant
intends to encompass within the language any structure presently
existing or developed in the future that performs the same function
as 300b and 329b. Gas that is distributed to lower back gas
transfer section 318b may be re-heated, if desired, by a lower back
gas heating means 303b, FIG. 5, before said gas passes through
slotted or perforated lower back gas discharge plate 327b via
apertures 329b, for discharge onto the back bottom and back side
portions of food product 310 in oven zone 302. Lower back gas
heating means 303b may be present in some embodiments and not
present in others depending upon the particular requirements for
the speed cooking conveyor oven and as with gas heating means 303a,
previously described, may be made of any material that accomplishes
heating of the gas. Apertures 300b and 329b are sized for a low
pressure drop, while providing and maintaining sufficient gas
velocities in the range of approximately 2000 ft/minute (609.6
meters/minute) to approximately 6000 ft/minute (1828.8
meters/minute) to properly cook the food product as described
herein. In some instances, velocities below 2000 ft/minute (609.6
meters/minute) and above 6000 ft/minute (1828.8 meters/minute) may
also be utilized. Apertures 300b are sized such that the majority
of the gas is supplied from the top back gas discharge plate 323b.
As with the front gas system, the resulting imbalance of gas flows
between the top back gas discharge plate 323b and lower back gas
discharge plate 327b is desirable because the top flows must
aggressively remove moisture produced and escaping from the top and
top side surface of the food product 310. The imbalance also serves
to heat, brown and/or heat and brown the food product 310.
[0046] The front and back gas supply systems, although
independently described herein, are the same configuration and
function to uniformly circulate hot gas flow across the top and top
sides and bottom and bottom sides of the food product, and return
the gas to the heating mechanism and gas flow means for re-delivery
to the oven zones. Although the same configuration is shown in the
exemplary embodiment no requirement exists for this symmetry and
the front gas supply system may be configured differently than the
back supply system, and the top gas supply systems configured
differently from the bottom. Indeed, each cook zone may be
configured differently than the other cook zones and many
combinations of configurations may be desirable for the particular
conveyor oven. When a single cook zone conveyor oven is desired,
various combinations, as previously described may also be
utilized.
[0047] As previously described, gas flow is delivered via four gas
transfer sections 317a, 317b, 318a, 318b which are located in the
top and bottom corners of each oven cavity 302 as shown in FIG. 5.
Gas flow transfer sections 317a, 317b; 318a and 318b extend the
width of each oven zone 302, although it is not required that the
gas flow transfer sections extend the entire length of the oven
zone. Gas transfer section 317a is located in the top front corner
of oven zone 302, FIG. 5, where top wall 303 intersects oven zone
front side wall 366; gas transfer section 317b in the top back
corner where top wall 303 intersects back side wall 367; gas
transfer section 318a in the lower front corner of the oven zone
302 where bottom wall 304 intersects front side wall 366; and gas
transfer section 318b in the lower back corner where bottom wall
304 intersects back side wall 367. Each gas transfer section is
sized and configured to deliver the appropriate gas flow for the
particular oven utilized. For example, in a smaller oven, the gas
delivery sections, indeed the entire oven, may be sized smaller in
proportion to the smaller footprint of the particular requirements,
and a larger oven may have proportionally larger gas delivery
sections.
[0048] As seen in FIG. 5, the front side and the back side gas
flows converge on food product 310 creating an aggressive gas flow
field on the food product surface that strips away the moisture
boundary layer. This turbulently mixed gas flow directed at the
food product can best be described as glancing, conflicting and
colliding gas flow patterns that spatially average the gas flow
over the surface area of the food product producing high heat
transfer and moisture removal at the food product surface, thereby
optimizing speed cooking. The gas flow is directed towards the top,
the bottom and the sides of the food product from the front and
back sides of the oven zone and the front and back side gas flows
conflict, collide and glance off each other at the food product
surface before exiting the oven zone through top gas egress opening
312. As used herein the term "mixing" refers to the glancing,
conflicting and colliding gas flow patterns that meet at and upon
the top surface, the bottom surface and the front and back side
surfaces of the food product and produce high heat transfer for
both conventional and speed cooking of the food product due to
spatial averaging of the gas flow heat transfer. The mixing gas
flows patterns are created within the oven zone and, when
appropriately directed and deflected, produce a high quality cooked
food product that can also be cooked very quickly. Although speed
cooking of high quality food product may be accomplished with this
invention, conventional cooking may also be accomplished by
adjusting the gas flow and microwave energy (in instances wherein
microwave energy is utilized) to the food product; or by use of gas
flow alone with no microwave energy. Enhancing the highly agitated,
glancing, conflicting, and colliding gas flow is the general upward
flow path the gas will follow, as shown in FIG. 5 through top gas
egress opening 312, as the gas exits the top of oven zone 302. This
upward gas flow draws also the gas from lower gas discharge
sections 318a and 318b thereby scrubbing the bottom of the food
product, pot, pan or other cooking vessel, by pulling gas flow
around the sides of said vessel, further enhancing the heat
transfer, as well as drawing the gas that scrubs the upper surface
up towards the oven zone top wall.
[0049] Returning to FIG. 5, top gas discharge plates 323a and 323b
are positioned within oven zone 302 such that the gas flow from top
gas transfer section 317a conflicts and collides with the gas flow
from top gas transfer section 317b upon the food product surface
and strikes the food product at an angle that is between zero
degrees and 90 degrees as referenced from the horizontal top wall
(where zero degrees is parallel to the horizontal top wall) and
lower gas discharge plates 327a and 327b are positioned within oven
zone 302 such that the gas flow from lower gas transfer section
318a conflicts and collides with the gas flow from lower gas
transfer section 318b upon the lower surface of the food product at
an angle that is between zero degrees and ninety degrees as
referenced from the horizontal bottom wall. Various cooking
requirements may require that the angle of the gas discharge plates
323a, 323b, 327a and 327b be adjusted, either during manufacture,
or adjustable within the oven after manufacture, in order for the
chef or cook to change gas flow velocity angles (vectors) to effect
different cooking profiles.
[0050] The number and placement of the apertures 300a, 300b, 329a
and 329b will vary according to the particular oven that is
desired. For example, a general purpose speed cooking conveyor oven
may be scaled to a baking oven by changing the number of apertures,
which may be fewer in number but be larger in size, thereby
allowing for a more gentle gas flow across the food product, and
producing proper delicate baking of the food product. If a browning
oven were desired, the apertures may be more numerous and smaller
in diameter. Additionally, the operator may desire more flexibility
of cooking and in this circumstance gas discharge plates 323a,
323b, 327a and 327b may be fabricated in a manner that allows for
quick change-out of the plates by the operator. As used herein the
term "aperture" refers to irregular slots, irregular holes or
irregular nozzles, regularly formed slots, regularly formed holes
or regularly formed nozzles or a mixture of regularly formed and
irregularly formed slots, holes or nozzles. FIG. 5 illustrates the
use of three rows of apertures 300a and 300b on top gas delivery
sections 317a and 317b, and two rows of apertures on the lower gas
delivery systems 318a and 318b, although more or fewer rows and
numbers of apertures may be utilized and applicant intends to
encompass within the language any structure presently existing or
developed in the future that performs the same function. The gas
delivery system as illustrated in FIG. 5 produces aggressive
glancing, conflicting and conflicting gas flow patterns 330a and
330b wherein an aggressive top glancing, conflicting and colliding
gas flow pattern 330a also interacts with the front top portion and
front top side portion of food product 310 and a similar back top
glancing, conflicting and colliding gas flow pattern 330b interacts
with the back top portion and top back side portion of food product
310. Aggressive glancing, conflicting and colliding gas flow 331a
interacts with the lower front and side portions of the food
product and gas flow 331b interacts with the lower back and side
portions of the food product. This cooking profile creates high
heat transfer capability by using the surface of the food product,
as well as the interference of flow fields to minimize boundary
layer growth. After the aggressive glancing and conflicting gas
flow patterns 330a and 330b contact or strike the food product they
are exhausted through top egress section 312 and cycle back through
the oven as described herein. The highly turbulent flow of the
conflicting gas patters described herein has several benefits.
First, the conflicting gas flow patterns create cook zone gas flow
that is averaged spatially, or a flow condition that tends to
average out the high and lows in flow variation for a given point
in the cook cavity greatly reduces the design complexity needed to
impose a uniform flow field over a cooking zone. In those instances
where gas transfer sections 317a, 317b, 318a and 318b are in use,
conflicting gas flows produce an "X" style gas flow wherein high
heat transfer rates needed for speed cooking average the flow
conditions over space and time, thereby producing uniform cooking
and browning.
[0051] Another advantage of the upward return gas path is that a
conveyor transport means may pass through the cook zones because
the two ends of cook cavity 302 are now free of any gas flow means
or microwave related subsystems (i.e., no blower return gas path or
microwave feeds). Also, uniform side browning is effected because
the bottom gas flow is drawn past the food product edges as the gas
flows up to egress point 312 within roof 303. Third, grease loading
in the return gas stream is reduced.
[0052] Gas flow control to the various zones is accomplished via
simple gas flow dampers or valves, referred to as nodes 390a, 390b,
391a, 391b, 392a, 392b. This approach maintains a relatively
constant flow through the oven thereby eliminating the need for
varying the blower speed. The gas flow within the conveyor oven, as
well as other functions of cooking appliance 301 are directed by
controller 334, FIG. 3. Speed cooking of individual food products
generally requires a separate cooking profile or recipe for that
food product. The speed cooking conveyor oven of the exemplary
embodiment is capable of cooking various food products at the same
time, therefore the oven controls must track the food products as
they move through the cook zones and adjust the gas flow energies,
and microwave energies (when microwave energy is used) of each cook
zone according to the cooking recipe that has been input by the
operator or input by a scanning device, or other device for each
food product. The cooking profile for a food product, referred to
herein as the "cooking recipe" may be quite complex and time and
labor expense associated with inputting cooking recipes may be
minimized by use of controller 334 loaded with predetermined
cooking recipes from a smart card, or loaded from an automated
product identification device, or other scanning and reading
devices may be utilized. Alternate embodiments will allow the
operator to place the food product onto conveyor means 399 in
loading zone 396, FIG. 4 and a unique product identification code
could be used to transfer recipes to the oven controller, thereby
eliminating manual cooking recipe inputs. Alternatively, manual
single button entries, or multiple button entries may be made by
the operator to input the cooking recipes and applicant does not
intend limitations concerning the use of the control system for
cooking recipes. Indeed optical scanners may be utilized at the
ingress end of appliance 301. The exemplary embodiment describes a
unique product identification code that is encoded with the correct
cooking recipe settings for each food product and the transfer of
information is accomplished using an Radio Frequency Identification
("RFID") tag placed on the food or food packaging. The RFID tag may
be programmed from the restaurant point of sale system and read by
the oven controller by any means known such as cable linked one way
communication, two way communication, wireless or other means and
applicant intends to encompass within the language any structure
presently existing or developed in the future that performs the
communication function. Reading of the RFID tag by controller 334
minimizes error associated with the operator imputing an incorrect
oven cooking recipe and allows the restaurant to optimize customer
service as the oven controller communicates with the point of sale
system during the cooking cycle for each food product. Controller
334 determines, among other things, the velocity of gas flow, which
may be constant or varied, or, may be constantly varied throughout
the cooking cycle and whether or not gas is delivered through the
previously described cooking nodes to cook zones 380, 381, 382. It
may be desired to cook the food product on one velocity throughout
the entire cooking cycle, or to vary the gas velocity depending
upon conditions such as a pre-determined cooking recipes, or vary
the gas velocity in response to various sensors that may be placed
within the cooking zone, oven return gas paths or various other
positions within the oven. The location and placement of said
sensors will be determined by the particular application of the
oven. Additionally, other means may be utilized wherein data is
transmitted back to controller 334, and thereafter controller 334
adjusts the cooking recipe in an appropriate manner. For example
sensors (temperature, humidity, velocity, vision and gas borne
chemical mixture level sensors) may be utilized to constantly
monitor the cooking conditions and adjust the gas flow, and
microwave energy, when used, accordingly within a cooking cycle,
and other sensors not described herein may also be utilized and the
speed cooking conveyor oven may utilize sensors that are not
currently commercially practical due to cost or other limitations
(such as laser, non-invasive temperature sensors and other sensors
that are currently too expensive to be commercially feasible), and
the speed cooking oven is not limited to those discussed herein, as
many sensing devices are known and utilized in and applicant
intends to encompass within the language any structure presently
existing or developed in the future that performs the same
function. Additionally, controller 334 may control the amount of
bleed gas flow through each odor filter 340, as previously
described. For example, oven zone 380 may contain a food product
that, upon conventional cooking, or speed cooking, will produce
larger amounts of airborne grease, smoke and odor than the food
products in the other cooking zones. In such an instance,
controller 334 may allow for more gas flow to pass through odor
filter 340 of oven zone 380 and either allow more or less gas flow
to odor filters that may be utilized for oven zones 381, 382 and to
adjust pre-heaters 341a, 341b of oven zone 380.
[0053] Gas flow may also be adjusted as a function of available
power. In the event, for example, the heating means of an all
electric speed cooking conveyor oven is requiring or utilizing a
large amount of power (larger than available power levels which may
vary according to location and local code and ordinance) it may be
desirable for controller 334 to reduce electrical power to the
heating means or other electrical components in order to conserve
available power. In a speed cooking conveyor oven, some systems may
be powered by electric current, but the electric power requirements
will not be as high as required for an all electric oven because
the energy required for gas heating and cooking will be provided by
the combustion of a hydrocarbon based fuel. In this event a
controller may not be required, indeed knobs or dials may be
utilized.
[0054] In an alternate embodiment, gas flow control may be
accomplished by gas flow control means, FIGS. 10, 11. As gas is
discharged into top front gas transfer section 317a, a selected
portion of said gas may be directed through apertures 300a within
gas discharge plate 323a by gas deflecting means 324a, shown in the
open position, FIG. 10. Gas deflecting means 324a is shown as
pivotally attached to gas discharge plate 323a, although, other
means for accomplishing said gas deflection may be utilized. For
example means such as normally open, normally closed, or normally
partially open and normally partially closed switched plates may be
used (wherein said plates slide along the inside of perforated
plate 323a to limit the aperture openings 300a of discharge plate
323a), and applicant intends to encompass within the language any
structure presently existing or developed in the future that
performs the same function as gas deflecting means 324a. Gas that
has not been discharged or deflected through apertures 300a flows
to lower front gas transfer section 318a via vertical transfer
section 319a. Pivotally attached to waveguide section 320a (when
waveguides are used and to sheet metal when not used) is a lower
gas transfer deflection mechanism 352a, FIG. 10 that operates to
limit the amount of gas that is transferred to lower gas transfer
section 318a. As used herein, the terms "flow control means" "gas
deflecting means" "transfer deflection mechanism" and "flow control
means" all have the same meaning and refer to means to control gas
flow within and to various parts of the conveyor oven. Indeed,
certain cooking operations may call for more gas flow to the lower
part of the conveyor oven, while other operations will call for
little or no gas flow to the bottom side of the oven for delivery
to the bottom of the food product. In those instances where little
or no gas flow is desired upon the bottom surface of the food
product, gas transfer deflection mechanism 352a may be closed in
order to allow all, or substantially all, of the gas flow into top
front gas delivery section 317a.
[0055] Gas that flows to lower front gas delivery section 118a may
be re-heated, if desired, by lower front heating means 303a, FIG.
10. After passing over heating elements 303a, the gas may be
further deflected by deflecting means 328a, FIG. 10, shown in the
open position. As gas deflecting means 328a is rotated, directional
control of the gas flow may be further refined, allowing for gas
flow to pass through the upper or lower rows of apertures of lower
gas plate 327a at various positions along food product 310 bottom
surface, FIG. 10. Although gas deflecting means 328a is shown as
pivotally attached to front slotted or perforated gas discharge
plate 327a, gas deflecting means 328a is not limited to the
pivotally attached means illustrated herein, and as described
elsewhere herein, applicant intends to encompass within the
language any structure presently existing or developed in the
future that performs the same function as gas deflecting means
324a, 352a, 328a, 324b, 352b and 328b to be discussed further
herein.
[0056] As gas is discharged into top back gas transfer section
317b, a selected portion of said gas may be directed through
apertures 300b within gas discharge plate 323b by gas deflecting
means 324b, shown in the open position, FIG. 11. Gas deflecting
means 324b is pivotally attached to gas discharge plate 323b,
although as with 323a, other means for accomplishing said gas
deflection may be utilized. For example means such as normally
open, normally closed, or normally partially open and normally
partially closed switched plates may be used (wherein said plates
slide along the inside of perforated plate 323b to limit the
aperture openings 300b of discharge plate 323b), and applicant
intends to encompass within the language any structure presently
existing or developed in the future that performs the same function
as gas deflecting means 324b. Gas that has not been discharged or
deflected through apertures 300b flows to lower front gas transfer
section 318b via vertical transfer section 319b. Shown as pivotally
attached to waveguide section 320b (when waveguides are used and to
sheet metal when not used) is a lower gas transfer deflection
mechanism 352b, FIG. 11 that operates to limit the amount of gas
that is transferred to lower gas transfer section 318b. As with the
front gas transfer system, certain cooking operations may call for
more gas flow to the lower part of the conveyor oven, while other
operations will call for little or no gas flow to the bottom side
of the oven for delivery to the bottom of the food product. In
those instances where little or no gas flow is desired upon the
bottom surface of the food product, gas transfer deflection
mechanism 352b may be closed in order to allow all, or
substantially all, of the gas flow into top front gas delivery
section 317b.
[0057] Gas that flows to lower back gas delivery section 118b may
be re-heated, if desired, by lower front heating means 303b, FIG.
11. After passing over heating elements 303b, the gas may be
further deflected by deflecting means 328b, FIG. 11, shown in the
open position. As gas deflecting means 328b is rotated, directional
control of the gas flow may be further refined, allowing for gas
flow to pass through the upper or lower rows of apertures of lower
gas plate 327b at various positions along food product 310 bottom
surface, FIG. 11. Although gas deflecting means 328b is shown as
pivotally attached to front slotted or perforated gas discharge
plate 327b, gas deflecting means 328b is not limited to the
pivotally attached means illustrated herein, and as described
elsewhere herein, applicant intends to encompass within the
language any structure presently existing or developed in the
future that performs the same function as gas deflecting means
324a, 352a, 328a, 324b, 352b and 328b.
[0058] In those instances wherein directional control of the gas
flow is desired, gas deflecting means 324a, 324b, 328a, 328b and
352a and 352b, FIGS. 9, 10 may be rotated such that gas flow is
diverted to selected apertures, thereby effecting a different gas
flow pattern and gas mixing upon and above the food product
surface. Additionally, in those instances wherein no bottom side
gas flow is desired, gas deflecting means 352a, 352b may be closed,
thereby allowing for little or no passage of gas flow to the lower
portion of the oven cavity. Various other adjustments of gas
deflecting means are possible and applicant intends to encompass
within the language any structure presently existing or developed
in the future that allows for combinations of open and closed
positions of apertures 300a, 300b, 329a and 329b by the various gas
flow control means described herein. Gas deflecting means 324a,
324b, 328a, 328b and 352a and 352b may be manually controlled,
automatically controlled via controller 334, controlled by other
mechanical or electrical means, or controlled via combination of
automatic and manual control and applicant intends to encompass
within the language any structure presently existing or developed
in the future that performs the function described herein
concerning adjustment of the gas deflecting means. In those
instances wherein gas deflecting means 324a or 324b allow little or
no gas through gas discharge plates 323a, 323b, and further wherein
little gas flow is desired through lower gas discharge plates 327a,
327b, a by-pass return gas flow conduit may be provided in order to
return gas flow to gas return conduit means 389. Additionally, in
those instances wherein gas directing means 328a, 328b allow little
or no gas through gas discharge plates 327a, 327b and less gas flow
is desired through gas discharge plates 323a, 323b, a conduit means
may be provided to return gas flow to return conduit means 389, or
alternatively to atmosphere or to gas bleed system previously
described for further odor and grease clean-up. Indeed, various and
multiple combinations of gas flow control exist, depending upon the
particular oven that is desired and gas flow may be directed to
many and various apertures throughout the conveyor oven in order to
accomplish the desired finished cooked product 310.
[0059] The oven of the present invention may also utilize microwave
energy to at least partially cook the food product. As seen in FIG.
5, front side microwave launching waveguide 320a is attached within
oven zone 302 to front side wall 305 between top front gas
discharge plate 323a and lower front gas discharge plate 327a. Back
side microwave launching waveguide 320b is attached within oven
zone 302 to back side wall 306 between top back gas discharge plate
323b and lower back gas discharge plate 327b. The microwave
waveguides are designed to distribute microwave power from
magnetrons 100, FIG. 8, uniformly from the back to the front of
oven cook cavity 302. The vertical distance above cavity bottom
wall 304 of waveguides 320a and 320b is such that, under normal
cooking conditions, approximately more than one third of the
microwave energy is available below food product 310, with the
balance of microwave energy available above food product 310.
[0060] As shown in FIG. 5, microwave energy 351a, 351b, FIG. 5, is
broadcast from waveguides 320a, 320b into oven zone 302 via a
slotted antenna 370, FIG. 8, wherein three or four narrow apertures
(slots) 370 are spaced along the waveguide. Various configurations
for microwave distribution have been utilized with varying results
and less than three slots may be utilized or more than three slots
may be used, and applicant intends to encompass within the language
any structure presently existing or developed in the future that
performs the same function. Important to an efficient and
inexpensive slotted microwave system, FIG. 9 is the slot length
382, slot width, 383, the spacing between the slots, slot end
spacing, angle of the slot relative to the long axis of the
waveguide, the number of slots per waveguide and the slot
orientation.
[0061] Slots 370 in waveguides 320a, 320b, are open to the cooking
cavity and must be covered or protected so that grease and other
contaminants cannot enter the waveguide and a durable and
inexpensive slot antenna cover may be utilized to protect such
slots 370. Slot antenna covers 106 FIG. 8, are configured to cover
slots 370 in waveguides 320a, 320b. Slot antenna covers 106 are
adhered to the surrounding stainless steel of waveguides 320a, 320b
using high temperature silicone rubber Room Temperature Vulcanizing
("RTV") sealant. This sealing approach creates high temperature
watertight seal between the cover and the surrounding metal.
Although an RTV sealant has been described in the exemplary
embodiment, other sealant means may be utilized to adhere antenna
covers 106 to waveguide 320a, 320b. The cover material must be
compatible with high temperature operation, must be of low loss
characteristics relative to microwave transmission, easily cleaned,
durable, and inexpensive. For good microwave compatibility,
materials with a dielectric constant less than 6 and a loss tangent
less that 0.2 have been found to provide such characteristics. Such
materials must be thin, generally less than 0.015 inches thick, and
be suitable for gluing using (RTV). A
Teflon(PolyTetraFluoroEthylene ("PTFE"))/fiberglass fabric produced
by Saint Gobain (ChemFab Product Number 10 BT) which has one side
treated to accepted silicone rubber and is 0.01 inches thick is
described in the exemplary embodiment and has shown to have little
impact on the microwave characteristics of the magnetron and
microwave waveguide system Results of Smith chart testing and water
rise experiments of the impedance of the waveguide and waveguide
antenna for slot angles greater than 17 degrees(as measured from a
horizontal centerline, 379, FIG. 9) and without antenna cover 106
are approximately the same.
[0062] Although two microwave waveguides, 320a, 320b and two
magnetrons, 100, are described per cooking zone, in other
embodiments the waveguides may be supplied by one larger magnetron,
or alternatively various numbers of magnetrons may be utilized and
the invention is not limited to two magnetrons per cooking zone and
applicant intends to encompass within the language any structure
presently existing or developed in the future that performs the
same function.
[0063] For optimum cooking, food product 310 is placed within oven
zone 302 upon conveyor transport means 399 a distance of at least
2.4 inches (for optimal cooking uniformity) from front side wall
305 and back side wall 306. The 2.45 inch measurement corresponds
to one half a microwave wavelength or 2.4 inches (for optimal
cooking uniformity) (E field null) for a 2.45 GHz microwave tube
(microwave) frequency. This spacing permits the E-field to expand
and become more uniform prior to coupling with the food product.
Other side spacing placement may be utilized with other types of
magnetrons systems.
[0064] The back side microwave waveguide is identical to the front
side system and microwave energy is broadcast from back waveguide
320b to oven zone 302 via slotted antenna 370 as previously
described for the front side. Although waveguides 320a and 320b are
configured in the same manner, infinite combinations of slot
designs, slot configurations, slot widths, slot lengths, numbers of
slots per waveguides and slot orientations are possible per
waveguide depending upon the type of oven desired. The microwave
energy field therefore propagates through the oven zone in an
evenly distributed pattern, coupling with the food product from all
directions, and providing an even electromagnetic energy
distribution throughout the oven zone without the need for a
mechanical stirrer to propagate the electromagnetic field.
Waveguides 320a and 320b are located on the front and back side
walls of the oven, and therefore do not interfere with oven zone
spent gas exhaust. Because microwave waveguides are located on the
side walls of the oven zone, they are not affected by food spills,
grease contamination, cleaning fluid contamination or other
contamination that normally affect a bottom launch microwave
system. The microwave system of the present invention will
therefore be less likely to be penetrated by grease, spills,
cleaning materials and other contaminants because the systems are
not located directly under the food product where hot contaminants
will drip. It is not required that side launch microwave waveguide
be employed and indeed microwave launching may be accomplished from
any oven cavity surface, with varying degrees of efficiencies.
[0065] Microwave waveguides 320a, 320b, FIG. 5 with slotted antenna
370 are positioned along the front and back cavity walls such that
cooking rack 308 is slightly below slots 370. In this manner,
microwave energy is directed towards the top and bottom of the food
product. For safety, microwave energy must be contained within
cooking tunnel 394 and historically conveyor ovens incorporated
long entrance and exit tunnels to attenuate the microwave leakage
escaping from the open oven tunnel ends. These long tunnels not
only require much additional floor space, but they result in oven
cavity heights of only a few inches thereby greatly limiting the
food products that can pass through such a conveyor oven. Our
invention eliminates the need for long entrance and exit tunnels
and short cooking cavity height by employing the indexing conveyor
approach coupled with tunnel doors, 397, 398 FIG. 1, as discussed
herein.
[0066] Exemplary food product flow is illustrated in FIG. 4. In
order to reduce controller 334 complexity, the conveyor transport
speed may be operated at a fixed rate. This approach establishes
dwell times wherein food product 310 remains in a given cook zone
for a fixed period of time. In addition to simplifying food recipe
development and cooking recipe algorithms, a fixed dwell time also
reduces complexities associated with conveyor drive mechanisms;
resulting in a less expensive and more reliable conveyor transport
means.
[0067] Food product 310 is placed upon conveyor transport means 399
and cook settings for product 310 may be inputted automatically or
manually, as previously described, into controller 334. Conveyor
indexing motion begins with the opening of ingress tunnel door 398,
FIG. 1 and egress tunnel door 397. After doors 397, 398 open,
conveyor transport means 399 moves in a direction toward the
cooking zones, (or zone) a distance such that food product 310
indexes, or moves forward to the first cook zone 380, FIG. 4 within
oven tunnel 394. Once conveyor transport means 399 stops, doors 398
and 397 close around conveyor belt 399 as shown in FIG. 7, and
initiation of the cooking cycle may begin. After conveyor means 399
comes to its initial stop, a second food product may be placed on
conveyor transport means 399 at loading position 396, FIG. 4. In
those instances wherein microwave energy is used, a microwave seal
must be achieved between conveyor belt 399 and doors 397, 398.
Interface wall 387, FIG. 7 is attached to belt 399 and doors 397,
398 close around interface wall 387. The wall spacing on conveyor
belt 399 corresponds to the pitch length (oven zone centerline to
oven zone centerline). The space between the partitions or walls
also defines the landing zone for product loading area 396, FIG. 4.
In addition to obtaining a seal for containment of microwave
energy, closed doors 397, 398 reduce heat losses associated with
open cooking tunnel ends where hot gas leaves the open tunnel ends
with cool ambient gas rushing in to replace the lost hot gas.
[0068] The door and wall microwave interface configuration between
movable doors 397, 398 and short wall 387, FIG. 7, on conveyor belt
399 is such that neither precise belt motion control (stopping at
an exact location) or metal to metal contact between door edge 399
and the wall 387 is required. The wall and belt design is axially
compliant. A one quarter wavelength choke 386, FIG. 7, is
integrated into the bottom edge of doors 397, 398. Allowing for
small displacement of the wall when the door closes is accomplished
by the combination of the inverted "V" shape which guides door
398,397 together with short wall 387 by a compliant (not rigid)
connection of wall 398 to belt 399. The inverted "V" shape has
sufficient length to support a one quarter wavelength choke
(approximately 1.2 inches). The indexing motion of speed cooking
conveyor appliance 301 results in microwave containment within the
cooking tunnel because the conveyor is stationary during the
cooking process.
[0069] With product 310 now in cook zone 380, controller 334 begins
the cooking recipe for food product 310. Cooking of food product
310 maybe completed within cook zone 380 or may be cooked in zones
381 and 382, FIG. 3, and it is not required that food product 310
utilize all three cook zones for completed cooking. Indeed, some
cook zones may be used to defrost frozen food product prior to
cooking, or partial defrost followed by cooking. Dwell, or cooking
time within each zone as previously described may be altered. The
exemplary embodiment utilizes a 50 second conveyor dwell setting
per cooking zone. Food product 310 entering cook zone 380 may
therefore have a cooking recipe of 50 seconds comprised of 25
seconds wherein 100% microwave energy and 100% gas flow is applied;
followed by 25 seconds in which 50% microwave energy and 100% gas
flow is applied.
[0070] At the completion of the first 50 second dwell period,
controller 334 begins the next indexing motion by opening tunnel
doors 398, 397, FIG. 1 and conveyor transport means 399 moves, or
indexes one pitch length forward, moving product 310 from first
cook zone 380 to second cook zone 381, FIG. 4. In the event a
second food product has been placed upon conveyor transport means
399 at loading position 396, FIG. 4, the second food product will
move, or index into cook zone 380. The second food product's
cooking setting may now be entered into controller 334 in the event
the operator had not previously entered the cooking program, or the
program had not been automatically loaded as previously described.
Once conveyor transport means 399 stops, tunnel doors 398, 397
again close and controller 334 executes the cooking settings for
the first food product in cook zone 381 and for the second food
product in cook zone 380. Each food product is then cooked with its
own cooking recipe. For example, the first food product in cooking
zone 381 may require 100% gas flow and no microwave energy for the
50 second dwell period, while the second food product in cooking
zone 380 may have 3 events programmed for the 50 second dwell
(e.g., 15 seconds of 100% gas flow with no microwave followed by 20
seconds of 100% microwave energy and no gas flow, followed by a
final 15 seconds of 50% microwave and 50% gas flow). The number of
events per cooking zone may be programmed in infinite combinations
and applicant does not limit the endless possible combinations of
cooking recipes by the exemplary embodiment.
[0071] At the completion of the second 50 second dwell period doors
398, 397 again open and the next conveyor transport means indexing
motion is initiated. Assuming a third food product has been placed
upon conveyor transport means 399 in holding area 396, third food
product 310 will index forward to cooking zone 380, while the
second food product will index forward to cooking zone 381 and the
first food product will index forward to cooking zone 382. With the
third food product now in cooking 380, each food product can now be
cooked with its own cooking recipe setting in the manner as
previously described. With the completion of the third dwell
period, doors 397, 398 again open and conveyor transport means 399
indexes forward one dwell length and first food product 310 is now
outside oven tunnel chamber 394 and resting upon transport means
399, ready for unloading by the operator.
[0072] As previously described, speed cooking conveyor 301 consists
of one or more discrete cooking zones. The simplest one zone design
will process only one product at a time. A multi-zone design of `n`
zones would have up to `n` products in conveyor oven tunnel at a
given time. The total capacity or speed cooking conveyor throughput
(products per hour) is a function of the number of cooking zones
and the total cook time for a product. For example, a one zone
speed cooking conveyor with a 150 second dwell time will process
approximately 24 products per hour. A three zone oven with 50
second dwell time zones and a total cook time of two and one half
minutes (3.times.50 seconds) will process approximately 72 products
per hour. A six zone speed cooking conveyor with 25 second dwell
times will process approximately 144 products per hour.
[0073] Because the food product is stationary in each cooking zone,
the energy flows imparted to each food product may be controlled.
Control of energy to the food product in a cooking zone includes
the means to modulate both the microwaves, when used, and gas flow
energies that may be introduced into the food product. A stationary
food product during cooking also permits the uniform application of
the cooking energies (microwave, convective and optional radiant).
Each cooking zone 380, 381, 382 has open ends with a conveyor belt
placed above and parallel to cook zone floor 304. The cook zones
are placed end to end with the conveyor transport means passing
through each cook zone and the zones are separate by a distance in
order to minimize the influence of gas flows or microwave energies
coupling between cook zones. The distances between cook zones will
be determined by the particular conveyor oven that is desired, and
the amount of interference between cook zones that may be
considered acceptable.
[0074] Although the exemplary embodiment illustrates the use of a
two blower design with one blower providing the gas flow to the
front of each cook zone and a second blower for gas flow to the
back of each cook zone, only one flow means, such as a blower may
be utilized, or more than two gas flow means may be utilized and
applicant intends to encompass within the language any structure
presently existing or developed in the future that performs the
same function.
[0075] Equipment bays for housing microwave circuit components,
magnetrons, cooling fans, electronics, line filters, and other
electrical components may be located on the front side of appliance
301.
[0076] For a three cooking zone speed cooking conveyor oven,
approximately 300 cubic feet/minute ("cfm") is utilized per cooking
zone, although more than 300 cfm and less than 300 cfm of gas per
cooking zone may be utilized. This produces a hot gas flow supply
loop, FIG. 5, wherein the cook zones are supplied with hot gas flow
once cooking zone valves 388a, 388b are opened. Actuation of the
valves may be accomplished using solenoids or stepper motors 310a,
310b, FIG. 5, or any other means known to accomplish the function
of opening and closing of valves 388a, 388b. This method permits
the blowers to operate at fixed speeds, and guarantees that
sufficient flow is always present for safe reliable operation of
the gas heating source and grease clean-up system.
[0077] As previously described, a single energy source, heating
means 314, with a single heat source controller, is used to supply
heat to the gas returning to the blower 316a, 316b. This approach
greatly simplifies the heating system as compared to distributing
heat sources among the various cooking zones. High power electrical
wiring or natural gas line connections may also be centralized. For
a gas fueled heating means, only a single burner and ignition
module are needed. The centralized approach results in both oven
construction simplification and reduced maintenance.
[0078] Gas heating power requirements per cook zone of the
exemplary embodiment are between approximately 5 and 7 kW for an
electric appliance and 24 to 34 kBtu/h for a direct fired natural
gas powered heater. An electric heater for the exemplary embodiment
is sized between approximately 15 and 21 kW, while the gas fired
gas heater would have a 72 to 102 kBtu/h need. For either power
source, a standard temperature controller could be employed (i.e.,
maintaining the blower discharge temperature). For either a gas
fueled or electric fueled appliance, as previously described,
appliance 301 may be scaled to permit use of available power
supplies. Additionally, a common gas heating means is ideal for
ease of installation, service, and the ability to incinerate grease
particles that come in contact with the very hot products of
combustion. Of course, the hot products of cooking by-product
combustion are mixed with the gas returning to the blowers,
resulting in a modest gas temperature increase of between
20.degree. F.(-6.67.degree. F.) to 60.degree. F. (15.56.degree. C.)
and a number of combustor types are suitable for this application
including a surface type burner.
[0079] Although the present invention has been described in
considerable detail with reference to certain preferred versions
thereof, other versions are possible. For example, various sizes of
conveyor ovens, both conventional and speed cooking may be made. In
these cases larger or smaller component parts may be utilized, and
fewer or more components may be employed. In the case where it is
desirable to make a smaller conveyor oven, one gas flow
acceleration means may be utilized instead of two; one microwave
system utilized instead of two; smaller or fewer thermal devices,
whether electric resistance or gas fired may be used. In cases
wherein it is desirable for a larger speed cooking oven, larger gas
flow systems and microwave systems may be added to accomplish a
larger speed cooking conveyor oven.
[0080] To summarize, the present invention provides for
conventional and speed cooking conveyor ovens utilizing hot gas
flow, and hot gas flow coupled with microwave energy in order to
achieve conventional and speed cooking of food products.
Conventional or speed cooking of food products five to ten times
faster than conventional cooking with food quality, taste and
appearance levels equal to and higher than that attained by
conventional cooking. The speed cooking conveyor oven is operable
on various power supplies and is simple and economical to
manufacture, use and maintain, and is directly scalable to larger
or smaller embodiments. The conveyor oven may operate as a gas
fired, electric resistance fired oven, a microwave oven or a
combination gas and microwave oven. Additionally, the invention may
be practiced wherein no gas deflection means are utilized, such as
in the exemplary embodiment, gas deflection means are utilized as
in alternate embodiments described herein. In cases wherein it is
desirable for a larger production conveyor oven, multiple conveyors
may be used with additional gas flow system and microwave
systems
[0081] Other modifications and improvements thereon will become
readily apparent. Accordingly, the spirit and scope of the present
invention is to be considered broadly and limited only by the
appended claims, and not by the foregoing specification. Any
element in a claim that does not explicitly state "means for"
performing a specific function, or "step for" performing a specific
function, is not to be interpreted as a "means" or "step" clause as
specified in 35 U.S.C. .sctn.112, 6. In particular, the use of
"step of" in the claims herein is not intended to invoke the
provisions of 35 U.S.C. .sctn.112.
* * * * *