U.S. patent application number 11/728370 was filed with the patent office on 2008-01-31 for gas conveyor oven with differentiated air flow.
This patent application is currently assigned to Moretti Forni S.p.A.. Invention is credited to Marco Moretti.
Application Number | 20080022993 11/728370 |
Document ID | / |
Family ID | 38514282 |
Filed Date | 2008-01-31 |
United States Patent
Application |
20080022993 |
Kind Code |
A1 |
Moretti; Marco |
January 31, 2008 |
Gas conveyor oven with differentiated air flow
Abstract
A gas conveyor oven has a conveyor belt for conveying an item
through a heating chamber in which separate parts or sides of the
item are to be concurrently heated at different temperatures. A
blower draws heated air from a gas burner into a ventilation
chamber in which a first baffle directs a first fraction of the
heated air from the blower into a first portion of the heating
chamber; and a second baffle directs a second fraction of the
heated air from the blower into a second portion of the heating
chamber. The second fraction of the heated air has a different rate
of flow than the first portion, because the first and second
baffles are positioned asymmetrically with respect to the heater,
so that the fraction of air deflected by each baffle onto a
different part or side of the item differs in volume and flow
rate.
Inventors: |
Moretti; Marco; (Pesaro PU,
IT) |
Correspondence
Address: |
COHEN, PONTANI, LIEBERMAN & PAVANE
551 FIFTH AVENUE, SUITE 1210
NEW YORK
NY
10176
US
|
Assignee: |
Moretti Forni S.p.A.
|
Family ID: |
38514282 |
Appl. No.: |
11/728370 |
Filed: |
March 26, 2007 |
Current U.S.
Class: |
126/21A |
Current CPC
Class: |
A21B 1/48 20130101; A21B
1/245 20130101 |
Class at
Publication: |
126/21.A |
International
Class: |
F24C 15/32 20060101
F24C015/32 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 27, 2006 |
IT |
PS 2006 A 000024 |
Claims
1. A gas conveyor cooking oven, comprising: a heating chamber;
means for conveying through said heating chamber, an article to be
cooked in said oven; a gas heater; means for drawing heated air
from said gas heater; means for directing into said heating chamber
heated air from said means for drawing and for splitting said
directed heated air into first and second fractions of the directed
heated air, such that said second fraction of the heated air has a
different rate of flow than said first fraction of the heated air;
and means for recycling said heated air to said gas heater after
said heated air passes through said heating chamber; and wherein
said first fraction of the heated air is directed into a first
portion of said heating chamber and said second fraction of the
heated air is directed into a second portion of said heating
chamber so that each fraction of the heated air cooks a different
part of the conveyed article at a different cooking heat as the
article is conveyed through said heating chamber.
2. The gas conveyor oven of claim 1, wherein said means for
conveying comprises a conveyor belt for conveying the article to be
cooked in said oven through said heating chamber.
3. The gas conveyor oven of claim 2, wherein said conveyor belt
comprises a mesh material.
4. The gas conveyor oven of claim 1, wherein said article is a food
to be cooked.
5. The gas conveyor oven of claim 4, wherein said article is pizza,
and wherein said first portion of the heating chamber is disposed
above said means for conveying so that the first fraction of the
heated air cooks toppings of the pizza and said second portion of
the heating chamber is disposed below said means for conveying so
that the second fraction of the heated air cooks the crust of the
pizza.
6. The gas conveyor oven of claim 1, wherein said gas heater
comprises a burner.
7. The gas conveyor oven of claim 1, wherein said means for drawing
comprises a blower.
8. The gas conveyor oven of claim 1, wherein said means for
directing includes at least a first baffle.
9. The gas conveyor oven of claim 8, wherein said first fraction of
the heated air is directed into a first feeder channel and said
second fraction of the heated air is directed into a second feeder
channel.
10. The gas conveyor oven of claim 9, wherein said first feeder
channel is larger than said second feeder channel.
11. The gas conveyor oven of claim 10, wherein said means for
directing further comprises a second baffle, said first baffle
directing said first fraction of the heated air into said first
feeder channel and said second baffle directing said second
fraction of the heated air into said second feeder channel.
12. The gas conveyor oven of claim 11, wherein said first baffle is
angled and defines a first apex, and said second baffle is angled
and defines a second apex, said first and second apices being
positioned asymmetrically with respect to said gas heater.
13. The gas conveyor oven of claim 12, wherein said first apex is
positioned lower in height than said second apex.
14. The gas conveyor oven of claim 11, further comprising means for
adjusting a position of at least one of said first and second
baffles.
15. The gas conveyor oven of claim 1, wherein said first portion of
said heating chamber is below said means for conveying, and said
second portion of said heating chamber is above said means for
conveying.
16. The gas conveyor oven of claim 1, further comprising a
temperature sensor within said heating chamber for monitoring a
temperature within said heating chamber; and means for controlling
at least one of said gas heater, said means for drawing and said
means for directing in response to said temperature sensor to
adjust the temperature in at least one of said first and second
portions of said heating chamber.
17. The gas conveyor oven of claim 1, wherein said means for
directing further comprises a deflector for directing the heated
air to at least one of said first and second portions of said
heating chamber.
18. A gas conveyor oven, comprising: a heating chamber; a conveyor
belt for conveying through said heating chamber a food item to be
cooked in said oven; a gas heater; a blower for drawing heated air
from said gas heater; a first baffle for directing a first fraction
of the heated air from said blower into a first portion of said
heating chamber; a second baffle for directing a second fraction of
the heated air from the blower into a second portion of said
heating chamber, at a different rate of flow than said first
portion of said heated air; and means for recycling said heated air
to said gas heater after said heated air passes through said
heating chamber; and wherein said first and second baffles are
positioned asymmetrically with respect to said heater, so that each
fraction of the heated air cooks a different part of the conveyed
food item at a different cooking heat as the food item is conveyed
through said heating chamber.
19. The gas conveyor oven of claim 18, wherein said food item is
pizza.
20. The gas conveyor oven of claim 18, wherein said conveyor belt
is formed of a mesh material.
21. The gas conveyor oven of claim 18, wherein said first fraction
of the heated air is directed into a first feeder channel and said
second fraction of the heated air is directed into a second feeder
channel.
22. The gas conveyor oven of claim 21, wherein said first feeder
channel is larger than said second feeder channel.
23. The gas conveyor oven of claim 22, wherein said first baffle
directs said first fraction of the heated air into said first
feeder channel and said second baffle directs said second fraction
of the heated air into said second feeder channel.
24. The gas conveyor oven of claim 23, wherein said first baffle is
angled and defines a first apex, and said second baffle is angled
and defines a second apex, said first and second apices being
positioned asymmetrically with respect to said gas heater.
25. The gas conveyor oven of claim 24, wherein said first apex is
positioned lower in height than said second apex.
26. The gas conveyor oven of claim 18, further comprising means for
adjusting a position of at least one of said first and second
baffles.
27. The gas conveyor oven of claim 18, wherein said first portion
of said heating chamber is below said conveyor belt, and said
second portion of said heating chamber is above said conveyor
belt.
28. The gas conveyor oven of claim 18, further comprising a
temperature sensor within said heating chamber for monitoring a
temperature within said heating chamber; and means for controlling
at least one of said gas heater, said blower, said first baffle and
said second baffle in response to said temperature sensor to adjust
the temperature in at least one of said first and second portions
of said heating chamber.
29. The gas conveyor oven of claim 18, further comprising a
deflector for directing heated air to at least one of said first
and second portions of said heating chamber.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention is directed to the field of conveyor
ovens and, more particularly, to a gas conveyor oven for use in
baking food with forced air circulation that provides an adjustable
and differentiated air flow.
[0003] 2. Description of the Related Art
[0004] The commercial bakery industry is extremely competitive.
This is especially true with respect to that segment of the
industry in which food is baked and then immediately served for
consumption, such as pizza. Commercial pizzerias use different
types of ovens; some, for example, use a static oven in which a
pizza is placed in the oven and then watched until it is ready to
be served. Alternatively, some commercial pizzerias employ a
conveyor oven, in which pizzas are placed on a conveyor belt to
move them through the oven at a controlled rate so that each pizza
is maintained in the oven for a predetermined period of time and
exits the oven fully cooked.
[0005] Conveyor-type pizza ovens have heating chambers which must
be heated to the desired temperature for baking pizza, either
through radiant heat that is electrically generated or generated by
flame-producing burners supplied with natural gas or liquefied
petroleum gas (LPG). To minimize the cooking time and optimize the
results, conveyor ovens commonly employ forced air heating, in
which air heated to the desired temperature is blown over the pizza
and then recycled to the heating element so that the pizza is
continuously maintained at the proper cooking temperature with
advantageous efficiency.
[0006] The cooking of pizza presents a special problem as compared
to other types of baking. Optimum preparation of pizza calls for
the bottom crust to be cooked at a higher temperature than the
toppings, so it is preferred that pizza ovens provide different
heating environments for the top and the bottom of the pizza.
[0007] In electric ovens, this may be accomplished by providing
separately controllable, distinct heating elements for each of the
top and bottom of the pizza. In one such known electric pizza oven
disclosed in published European Patent Application No. 1,442,660
A1, air is circulated through upper and lower diffusers, in which
separate upper and lower heating elements are disposed. The upper
and lower heating elements heat the air in their respective
diffusers to different temperatures, so that the air forced over
the toppings is slightly cooler than the air forced onto the crust,
thereby yielding an optimum cooking performance for this use.
[0008] This procedure is not, however, practical for ovens which
employ a gas burner to generate heat, because it is preferred in
such ovens that only one burner be used as the heat source, rather
than two. Such ovens moreover sometimes require on and off cycling
of the burner to maintain the desired cooking temperatures, which
is an inefficient use of the burner and may lead to uneven cooking
results. It is preferred that the burners remain "on", but this can
lead to too much heat on the toppings and known ovens do not always
adequately handle the need to maintain different cooking
temperatures.
[0009] There is accordingly a need in the art for a gas conveyor
oven which can provide a differentiated heating environment for the
top and bottom of an item being cooked, while using only a single
burner.
[0010] There is a further need in the art for a gas conveyor oven
which can efficiently use a single burner to provide differentiated
heat to the top and bottom of an item being cooked, without the
need for supplemental heating elements.
SUMMARY OF THE INVENTION
[0011] It is therefore an object of the present invention to
provide a gas conveyor oven which addresses the needs of the art
and is simple, safe, economical and efficient.
[0012] It is another object of the invention to provide a gas
conveyor oven that provides differentiated forced air flow, and
therefore differentiated heat, to two different regions of a
cooking chamber.
[0013] Briefly stated, a preferred embodiment of the invention is
implemented in a gas conveyor oven that has a conveyor belt for
conveying a food item through a heating chamber. A blower draws
heated air from a gas burner into a ventilation chamber in which a
first baffle directs a first fraction of the heated air from the
blower into a first portion of the heating chamber; and a second
baffle directs a second fraction of the heated air from the blower
into a second portion of the heating chamber. The second fraction
of the heated air has a different rate of flow than the first
portion of the heated air, because the first and second baffles are
positioned asymmetrically with respect to the heater, as a result
of which the fraction of air deflected by each baffle differs in
both volume and rate of flow.
[0014] Other objects and features of the present invention will
become apparent from the following detailed description considered
in conjunction with the accompanying drawings. It is to be
understood, however, that the drawings are designed solely for
purposes of illustration and not as a definition of the limits of
the invention, for which reference should be made to the appended
claims. It should be further understood that the drawings are not
necessarily drawn to scale and that, unless otherwise indicated,
they are merely intended to conceptually illustrate the structures
and procedures described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The invention is illustrated in the attached drawings, in
which like numerals designate like elements, and wherein:
[0016] FIG. 1 is a cross-section of a gas conveyor oven constructed
in accordance with a preferred embodiment of the invention, taken
across the direction of travel of the conveyor;
[0017] FIG. 2 is a top plan view, partially broken away and in
partial cross-section, of the gas conveyor oven of FIG. 1; and
[0018] FIG. 3 is a cross-section of the gas conveyor oven of FIGS.
1 and 2, taken parallel to the direction of travel of the
conveyor
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0019] In FIG. 1, there is shown, generally at 100, a gas conveyor
oven constructed in accordance with the present invention. A mesh
conveyor belt 1 carries items to be heated through a heating
chamber 2, which can be inspected through a glass front door 3 and
is insulated on all sides with thermal insulation material 4 stored
in interspaces in oven 100.
[0020] A gas fed burner 5 (FIG. 2) supplies heat to heating chamber
2 with a flame column 6 positioned parallel to the direction of
movement of conveyor 1, which is situated in front of and at
essentially the same level as flame column 6.
[0021] Burner 5 is equipped with a continuous flame modulator,
preferably composed of a gas supply valve connected to a Venturi
air intake tube serving a variable speed electronically adjustable
electric fan, for automatic regulation of the gas flow to burner 5
based on the incoming flow of air and adjusted by the variable
speed fan and consequent mixing of the two fluids in order to
optimize the stoichiometric combustion ratios.
[0022] A partition 7 is displaced behind flame column 6 and between
flame column 6 and a blower 8 within heating chamber 2. Blower 8 is
centrally positioned with respect to flame column 6. Blower 8 is
preferably a left rotating centrifugal fan located on the side of
flame column 6 opposite heating chamber 2. Blower 8 centrally draws
in air heated by flame column 6 and evenly expels it peripherally
into a ventilation chamber 10 extending parallel to the length of
heating chamber 2.
[0023] Blower 8 includes a motor 9 located in the rear of oven 100,
externally of ventilation chamber 10, and operates a second
external coaxial centrifugal fan 11. Fan 11 circulates forced air
outside of heating chamber 2 and within a peripheral space 12
delimited by a sheet metal covering 13 on the exterior of oven 100
to keep the exterior of oven 100 at a safe temperature.
[0024] Left and right angular baffles 14 and 15 (FIG. 3) are
located on the vertical sides of ventilation chamber 10 and have
respective apices 14A, 15A. Left baffle 14 has its apex 14A located
higher than the axis of rotation of blower 8, while the apex of
right baffle 15A is roughly level with the axis of rotation of
blower 8.
[0025] Three radial deflectors 16A, 16B and 16C are positioned
within ventilation chamber 10. A first deflector 16A is positioned
below the left angular baffle 14, and the other two deflectors 16B
and 16C are positioned respectively below and above right angular
baffle 15.
[0026] Ventilation chamber 10 opens into lower feeder channel 17
and upper feeder channel 18, which each have their respective
openings along the entire length of ventilation chamber 10 (see
FIG. 3). As explained hereinbelow, the opening of lower feeder
channel 17 is larger than the opening of upper feeder channel 18
(see FIG. 1).
[0027] Lower and upper feeder channels 17, 18, extend respectively
below and above flame column 6 and then diagonally into heating
chamber 2 respectively below and above conveyor belt 1 along the
entire length of conveyor belt 1 within heating chamber 2. Lower
and upper feeder channels 17, 18 empty into heating chamber 2
through respective lower and upper diffusers 19, 20 which define
respective series of lower and upper calibrated holes 19A, 20A.
[0028] Lower and upper splitters 21, 22 are positioned in
respective lower and upper feeder channels 17, 18.
[0029] The article or item to be heated is transported by conveyor
belt 1 through a transport canal 23. Transport canal 23 is bounded
by conveyor belt 1, upper diffuser 20 and front door 3, and is
partially closed at its rear by a deflector 24 that includes a
lower opening 25 extending along the length of deflector 24.
[0030] Positioned rearward of deflector 24 is the convex face of a
curved partition 26. Partition 26 extends substantially parallel to
flame column 6 along its entire length within lower and upper
feeder channels 17, 18. The space between the outer extent of
partition 24 and lower and upper feeder channels 17, 18
respectively defines lower and upper gaps 27, 28.
[0031] Disposed within heating chamber 2, and preferably located in
upper output feeder channel 18, are electronic temperature sensors
29 that are operatively connected to burner 5, as further explained
below.
[0032] In the operation of gas conveyor oven 100, blower 8 draws
hot air from around flame column 6, and expels it peripherally
outward by its counter-clockwise rotation. The expelled heated air
is intercepted by left and right angular baffles 14, 15, which are
configured with respective apexes 14A, 15A defined above and
alongside the horizontal disposition of fan 8 (see FIG. 3). In
relation to the rotation of fan 8, the flow of heated air is shaped
and directed by the asymmetrical orientation of baffles 14, 15, and
magnified by deflectors 16A, 16B and 16C, to split the flow of
heated air into two streams that are respectively channeled into
lower and upper feeder channels 17, 18. The heated air that is
directed downward has a higher flow rate, by virtue of the
relatively greater volume of lower feeder channel 17 as compared to
upper feeder channel 18, since the positioning of apex 14A above
the center of blower 8 causes a relatively greater proportion of
the otherwise evenly distributed heated air to flow downward into
lower feeder channel 17.
[0033] In this manner, through lower and upper feeder channels 17,
18, the flow of heated air reaches and crosses diffusers 19, 20 and
is forced below and above conveyor belt 2. The greater flow of
heated air to lower feeder channel 17 provides more heat to the
bottom of the pizza crust transported on conveyor belt 2, while at
the same time providing less heat to the upper feeder channel 18 to
properly cook the toppings carried on the top of the crust.
[0034] After circulating over and under the conveyor belt 2 for
cooling the transported article, the flow of air coming through
diffusers 19, 20 is centrally drawn into transport canal 23 and
passes through opening 25 below deflector 24 and into curved
partition 26. The heated waste air is then split and channeled
through lower and upper gaps 27, 28, thus returning to flame column
6 for reheating and return to the forced air cooling operation.
Recycling of the already-heated air back to flame column 6
efficiently decreases the overall cost of operation of conveyor
oven 100.
[0035] Even with just one burner and one blower, as is preferred,
this labyrinthian structure can achieve uniform and optimal cooking
of pizzas by directing the heat where it is needed, the proper
temperatures being maintained without shutting off flame column 6.
The intensity of the flame is instead modulated by adjusting the
parameters to achieve the optimum mixture of combustible gas and
air, thus resulting in more efficient use of gas as compared to the
normal waste of gas in "on-off" systems, while offering uniform
cooking of pizzas.
[0036] In particular, in a currently preferred embodiment of the
invention, temperature sensors 29 located in upper feeder channel
18 monitor the temperature of the heated air where it is at its
maximum temperature. The temperature of the heated air may then be
electronically controlled based on preset optimization parameters
such as regulation of the variable speed electric fan serving a
Venturi air intake tube that is connected to the gas supply valve
of the continuous flame supply modulator of burner 5. This valve
suitably increases or decreases the supply of combustible gas to
flame column 6 based on the temperature detected by sensors 29, and
thus increases or decreases the intensity of flame column 6. The
desired temperature is accordingly maintained by constantly
optimizing the stoichiometric ratio for the air-gas mixture.
[0037] There are of course alternative ways of achieving these
functions, while using the innovative construction herein
described. The system presented here can be realized with
structures equivalent to those described as would be appreciated by
those of ordinary skill in the art, and those of ordinary skill
would also appreciate that the parameters and structures hereof may
be varied without under experimentation to realize the benefits
provided by the invention.
[0038] For example, the structure of the ventilation chamber can be
modified to change the running direction of the blower to thereby
provide a more sustained flow in the lower duct than in the upper
duct. In other embodiments, the relative flow of air to the lower
and upper feeder channels 17, 18 can be adjusted by providing means
for varying the orientation and positioning of at least one of the
baffles 14, 15, such as a motor 30 operative to raise and/or lower
the baffle.
[0039] As should now be apparent, the preferred system and
contemplated variations offer numerous advantages, including the
provision of an implementation that successfully yields a gas
conveyor food oven with only a single burner and a single blower
while achieving high efficiency and desirable adjustability.
[0040] It will also be appreciated that the gas conveyor oven of
the invention will have utility in any heating application in which
it is desired to use a single heater to heat two sides of an item
at different temperatures or heat levels, even where the two sides
are not top and bottom but, rather, left and right, or front and
back. One of ordinary skill in the art can readily modify the
constructions described herein without undue experimentation to
adapt the inventive gas conveyor oven for a particular application
or utility.
[0041] It will also be appreciated by those of ordinary skill in
the art that the relative rate of heated air flow to the upper and
lower feeder channels may be adjusted or set by the relative
positioning of apices 14A and 15A with respect to each other and to
blower 8, to thereby set the relative heated air flow rates through
the feeder channels to the desired proportion.
[0042] Thus, while there have shown and described and pointed out
fundamental novel features of the invention as applied to preferred
embodiments thereof, it will be understood that various omissions
and substitutions and changes in the form and details of the
devices illustrated, and in their operation, may be made by those
skilled in the art without departing from the spirit of the
invention. For example, it is expressly intended that all
combinations of those elements which perform substantially the same
function in substantially the same way to achieve the same results
are within the scope of the invention. Moreover, it should be
recognized that structures and/or elements shown and/or described
in connection with any disclosed form or embodiment of the
invention may be incorporated in any other disclosed or described
or suggested form or embodiment as a general matter of design
choice. It is the intention, therefore, to be limited only as
indicated by the scope of the claims appended hereto.
* * * * *