U.S. patent application number 09/960367 was filed with the patent office on 2002-06-13 for high efficient convection fryer with continuous filtration.
This patent application is currently assigned to Pitco Frialator, Inc.. Invention is credited to Savage, Steven J., Wendel, Thomas DeWayne.
Application Number | 20020069767 09/960367 |
Document ID | / |
Family ID | 24909591 |
Filed Date | 2002-06-13 |
United States Patent
Application |
20020069767 |
Kind Code |
A1 |
Wendel, Thomas DeWayne ; et
al. |
June 13, 2002 |
High efficient convection fryer with continuous filtration
Abstract
An improved efficient deep fat fryer is described. Heat exchange
within the fryer tank is facilitated by a "U" shaped burner tube
which is cantilever mounted from a side of the tank and a burner
system is provided to circulate in a spiral pathway products of
combustion through the burner tube. An internal turbulator baffle
is provided to both facilitate the spiral circulation through the
tube and to facilitate heat transfer from the combustion gases to
burner tube walls. Exhaust gases are circulated downwardly from the
burner tubes to a plenum beneath the tank which also has heat
transfer baffle plates to facilitate heat exchange. Ultimately the
products are expelled through a flue. The system further comprises
filter bags for continuously filtering the oil which are disposed
in a sump at the surface of the oil so that oil continually spills
from the tank into the sump where it is filtered preferably by one
or more bags of cloth material. Other types of filters could be
used such as metal or paper or a synthetic in combination with
paper so long as porosity is maintained and a filter powder could
be used. The system provides a pump for recirculating the filtered
oil to the tank.
Inventors: |
Wendel, Thomas DeWayne;
(Nashua, NH) ; Savage, Steven J.; (Concord,
NH) |
Correspondence
Address: |
Donald C. Casey
Suite 100
311 North Washington Street
Alexandria
VA
22314
US
|
Assignee: |
Pitco Frialator, Inc.
|
Family ID: |
24909591 |
Appl. No.: |
09/960367 |
Filed: |
September 24, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09960367 |
Sep 24, 2001 |
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09511377 |
Feb 23, 2000 |
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09960367 |
Sep 24, 2001 |
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08724233 |
Sep 27, 1996 |
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Current U.S.
Class: |
99/403 ;
99/408 |
Current CPC
Class: |
Y10S 210/08 20130101;
A47J 37/1223 20130101; A47J 37/1247 20130101 |
Class at
Publication: |
99/403 ;
99/408 |
International
Class: |
A47J 037/12 |
Claims
In the claims
1. A deep fat fryer comprising: a housing having a front, sides and
back, an upwardly opening tank for holding cooking oil disposed
within said housing and having sides and a bottom, an upwardly
opening sump having sides and a bottom, disposed within said
adjacent tank, and means for directing oil, overflowing said tank
from the opening thereof, into said sump; a U-shaped burner tube
having first and second legs extending across said tank, and
attached by an end of a first leg to a side of said tank, burner
means mounted in said housing and communicating with the interior
of said tube through the end mounted on the side of said tank for
directing products of combustion therethrough, means carried by
said burner tube for circulating said products of combustion
through said tube in a spiral path from the burner, successively
through the first and second legs of said tube; filter means
removably mounted in said sump for filtering oil overflowing from
said tank thereinto; and circulating means for continuously
withdrawing filtered oil from said sump and re-injecting said oil
into said tank.
2. The fryer of claim 1 further comprising a jet tube extending
across an interior side of said tank opposite said sump adjacent
the upper portion of said tube, said jet tube coupled to said
circulating means and adapted to inject filtered oil into said
tank.
3. The fryer of claim 2 further comprising means carried by said
tank for, in conjunction with said jet tube, circulating oil within
said tank to continually sweep debris from the tank bottom and to
the surface of the tank.
4. The fryer of claim 1 wherein the bottom of said tank defines a
port and the second leg of said tube terminates in a downwardly
directed elbow extending through said port and adapted to expel
circulated combustion gases therefrom.
5. The fryer of claim 4 wherein an exhaust plenum is provided
within said housing surrounding the bottom of said tank said plenum
being in communication with said tube through the tank port; and
flue means mounted on said housing in communication with said
plenum for expelling circulated combustion products therefrom.
6. The fryer of claim 1 wherein said circulating means within said
burner tube includes a pair of baffle plates mounted in each leg
thereof, disposed at an acute angle to the longitudinal axis of
said tube leg, each plate having a central opening therethrough,
said plates being in a heat exchange relationship with the
combustion gases passing through said tube.
7. The fryer of claim 1 wherein said sump is disposed abutting a
side of said tank and said means for directing overflow oil from
said tank to said sump includes a gutter extending between an edge
of the tank opening and an edge of the sump opening.
8. The fryer of claim 7 wherein said sump further comprises at
least one mesh basket received therein, said basket opening
upwardly and normally aligned with the sump opening and abutting
the sides thereof said basket being removable from said sump
through its opening.
9. The fryer of claim 8 wherein said filter means includes at least
one upwardly opening porous, bag adapted to be suspended within
said basket.
10. The fryer of claim 9 wherein said filter means includes a plate
adapted to be removably attached to said bag at the opening thereof
and dimensioned to engage at least a pair of sides of said basket
to support the bag suspended therein.
11. The fryer of claim 10 wherein said basket includes a flange
surrounding the opening and extending outwardly therefrom, said
flange dimension to engage the sides of said sump so that oil
entering the sump will pass through the opening of said basket.
12. The fryer of claim 11 wherein said plate defines a central
opening therethrough and is dimensioned to engage the flange on
said basket opening so that oil entering the sump will pass through
the opening in said plate, into said bag, therethrough into said
basket, and therethrough into said sump.
13. The fryer of claim 12 wherein a pair of baskets and a pair of
filters therefor are provided.
14. The fryer of claim 12 further comprising means for removing
said plate and suspended bag from said basket carried by said
plate.
15. The fryer of claim 12 further comprising means for removing
said basket from said sump, carried by said basket.
16. The fryer of claim 10 wherein said bag defines a rectangular
upper opening and depending sides, said sides tapering inwardly to
a bottom, the opening having opposed shoulders extending inwardly
from opposed sides, said shoulders adapted to removably engage
opposite ends of said plate.
17. The fryer of claim 16 wherein said bag is rectangular in
cross-section and the opening therein is defined by said opposed
shoulders and portions of edges a pair of opposed sides.
18. The fryer of claim 9 wherein said bag is comprised of cloth
which is 100% virgin cotton, unbleached, 9.7 oz., sateen weave
96.times.60 (pic per inch) with air permeability of 15-20 CFM,
sateen side inward.
19. In a deep fat fryer including a housing, a tank, means for
heating oil in said tank, sump means for accepting overflow oil
from said tank, filter means for filtering the overflow oil and
circulating means for returning filtered oil to the tank, all
contained in said housing, the improvement comprising: at least one
filter removably suspended in said sump and adapted to receive said
overflow oil, said filter being sufficiently porous so that said
oil passes therethrough with entrained sediment therein being
retained in said filter, whereby when said filter fills with
sediment it can be removed and replaced, or cleaned.
20. The fryer of claim 18 where said bag is cotton, of sateen weave
having the sateen side the inside surface of the bag.
21. The fryer of claim 20 wherein the bag is 100% virgin cotton,
unbleached, 9.7 oz., and the sateen weave is 96.times.60 (pic per
inch) with air permeability of 15-20 CFM.
22. A disposable filter bag for filtering hot cooking oil from a
deep fat fryer to remove sediment therefrom comprising: a
rectangular in cross-section, upwardly opening four sided, cloth
bag of 100% virgin cotton (unbleached) sateen weave 96.times.60
(Pic per inch), with air permeability of 15-20 CFM and sateen side
disposed on the inside the upper opening being rectangular and
defined by a pair of opposed shoulders extending across the end
portions of the pair of elongated sides and the exposed edges of
said sides.
23. The bag of claim 22 wherein the sides taper downwardly and
inwardly to form a bottom of said bag.
24. A method for efficiently cooking food in a deep fat fryer
comprising the steps of: providing a deep fat fryer having a tank
with sides and a bottom for containing cooking oil, means within
said tank for heating the oil, a sump disposed adjacent a side of
the tank for receiving overflowing oil therefrom, and means for
re-circulating the oil from the tank to the sump and for
withdrawing oil from the sump and circulating it through the tank;
providing a porous filter, mounting said filter in said sump;
circulating overflow oil from the tank through said filter in said
sump and filtering said oil therein to remove entrained sediment
therefrom; withdrawing filtered oil from said sump, and returning
said oil to said tank, periodically removing said sediment filled
bag from said sump and replacing it.
25. The method of claim 24 wherein said filter is a porous bag,
each bag having a rectangular inlet, opening and means at the
opening therein for suspending said bag in said sump.
26. The method of claim 24 further comprising continuously
injecting filtered oil into said tank along a side thereof opposite
said sump; sweeping the bottom of said tank with said injected oil
to circulate debris toward said sump.
27. The method of claim 26 further comprising providing a jet tube
extending along a side of said tank opposite said sump said tube in
communication with said oil re-circulating means for injecting said
oil into said tank.
28. The method of claim 25 wherein said filter consists of at least
one porous cloth bag of 100% virgin cotton cloth, sateen weave
96.times.60 (pic per inch) and air permeability of 15-20 CFM, the
sateen side being the inside surface of said bag.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to U.S. patent applications Ser.
Nos. 08/626,318 and 08/626,319, filed Apr. 2, 1996 and assigned to
the Assignee of this invention.
FIELD OF THE INVENTION
[0002] This invention relates to deep fat fryers and in particular
to deep fat fryers in which the oil used for cooking is filtered on
a continuous basis so that food particles in the cooking oil are
quickly removed to minimize their effect upon the taste of the food
being cooked. The oil removed from the cooking bath is filtered and
returned to the heated bath on a continuous basis.
DESCRIPTION OF THE PRIOR ART
[0003] Commercial deep fat fryers typically are heated by heat
tubes extending through the oil bath so that food being cooked is
disposed above the heat tubes and dislodged particles from the food
during cooking are allowed to settle through the bath and through
the heat tubes into a sump area therebelow wherein the accumulated
oil is of necessity at a lower temperature. As a result,
disagreeable flavors from the overcooked food particles are allowed
to penetrate the cooking oil bath and from there into the food
being cooked. In the event different food products are cooked in
the same bath, the flavors commonly are interchanged. Finally, this
design also is inherently inefficient because the oil in the sump
typically is periodically drained, filtered and returned to the
cooking bath. If the return oil is not re-heated, its injection
into the bath will temporarily lower the bath temperature, and
interfere with the cooking procedure. Therefore, a separate
re-heater for the return oil is required.
[0004] In deep fat fryers, it is essential to maintain the optimum
cooking temperature in the oil bath. This can be difficult when
frozen food products are, for example, placed in a basket and
submerged frozen in the bath. There is no way to avoid a downward
fluctuation in the bath temperature in this event, and, the bath
temperature must be returned to the optimum as quickly as possible.
Food cooked at below optimum temperature will retain oil, become
soggy, and generally not exhibit the desired crispness.
[0005] In U.S. Pat. No. 4,623,544, a weir is provided at the
surface of the cooking bath and oil is continually allowed to flow
over the weir and downwardly into a sump. The oil entering the sump
is filtered by a cylindrical mesh filter, re-heated in a separate
heat exchanger and continually re-injected into the oil bath. The
oil bath itself is not exposed directly to heat tubes and the sump
is physically separated from the oil bath. The device described
then while continuously filtering oil, tends to retain food
particles in the bath because of the combination of the weir and
downstream filter, and most importantly, is heat inefficient
because of the exposed piping to and from the heat exchanger which
is remote from the oil bath.
[0006] In U.S. Pat. No. 3,977,973, a heat tube is provided in the
lower portion of the bath and oil is withdrawn from the lower
portion of the bath whereupon it flows through filters and is then
re-injected into the bath at the bottom portion adjacent to the
heat tubes. While this device is capable of filtering on a
continuous basis, the food particles to be removed from the bath
must first settle through the bath and through the heat tubes
before being withdrawn from the bath. There is therefor time while
the settling occurs for the food particles to transmit undesired
flavors into the bath. In addition because the heated oil is
re-injected into the bottom of the tank containing the oil bath,
there is the possibility that circulation within the bath will not
be sufficient so that it can be easily maintained at a uniform
temperature.
[0007] Similarly in U.S. Pat. No. 5,404,799, a filter mechanism is
placed at the bottom of the tank containing the oil bath so that
oil is continually removed from the oil bath through the filter.
While this is a continuous filtering system it does not provide for
removal of food particles within the bath which have settled to the
bottom thereof Furthermore, while the filter can be removed to be
cleaned, the bottom portion of the tank adjacent the filter and
surrounding the same would have to separately cleaned manually.
[0008] Similar filtering systems are shown for example, in U.S.
Pat. Nos. 4,768,426 and 4,962,698.
[0009] Accordingly there is a need for a continuous filter system
which also can provide for rapid cleaning of the filter system and
for efficient heating of the oil bath.
SUMMARY OF THE INVENTION
[0010] It has been discovered that a unique heat tube design can
provide efficient heating on a continuous basis for the oil bath in
a deep fat fryer. In the device of this invention, a "U" shaped
heat tube is provided extending in cantilever fashion from a side
of the fryer into the oil bath. The heat tube contains a baffle
arrangement so that combustion gases from a burner at one end will
travel in a spiraling stream through a first leg of the "U" shaped
burner tube and around the end return portion without scorching the
end portion, and through the second leg. The combustion gases then
flow downwardly below the fryer tank into a plenum wherein
additional baffles are provided to improve the heat transfer within
the system. Finally, the plenum exhausts into a flue. In one
embodiment it is intended that a blower be operated on a continuous
basis and that the burner is operable in at least two modes, a low
fire mode and a high fire mode. The blower is preferably designed
to also draw ambient air through the control box for the unit to
cool the controls before expelling the air into the burner system
as combustion air. It is further intended that the burner be
operated in a low fire mode on a continuous basis until a
thermostatic sensor calls for the high fire mode and at completion
of the high fire mode that the burner will return to a low fire
mode so that in a day's operation the burner will not normally have
to be relighted. The blower also changes the air flow responsive to
a change in burner mode so that the cooling effect through the
control box will reflect the increased or decreased heat generated
by the burner.
[0011] In an alternative embodiment the burner can be operated
intermittantly. When sensors call for heat, the burner will fire in
the low mode and then in the high mode until the heat requirement
is met. The burner will then shut off until sensors again call for
heat, meanwhile the blower operates continuously as described in
the first embodiment.
[0012] The invention also includes a continuous filtering system
including a sump which is disposed beside the fryer tank so that
oil from the surface of the tank will continuously spill over the
edge of the tank into the sump. In a preferred embodiment, unique,
filter bags are provided of cotton cellulose material in the sump
so that as the oil falls by gravity through the sump, food
particles will be retained within the filter bags. The lower
portion of the sump then will accumulate oil which will be drawn
off by a suction pump, and the then filtered oil returned to the
tank to be injected into the bath by a jet tube disposed at the
upper portion of the heat tubes and opposite the sump. This tube in
effect causes a turbulence that sweeps debris from the tank bottom
up to the surface and into the sump. It also assists in penetrating
food to be cooked so that it cooks faster and more efficiently.
[0013] When the filter bags have filled with sediment, a vacuum
gage and/or sensor in communication with the suction pump will
provide a signal indicating the necessity to shut the system down
and replace the filter bags. Merely suctioning the residual oil
from the bags and lifting the bags from the sump and inserting new
bags is normally all that is required before restarting the
system.
[0014] In the preferred embodiment the filter used consists of
filter bags of 100% virgin cotton unbleached, 9.7 oz. sateen weave,
96.times.60 (pic per inch), with an air permeability of 15-20 CFM.
The sateen side is inside in the preferred embodiment.
[0015] Alternatively, the filter bag may be of metal, either a mesh
type, perforated metal, or a porous metal of the sintered type.
Furthermore, paper or a cellulose paper with a synthetic mix may
also be used and the synthetic constituent of the filter bags may
be such materials as rayon, nylon, Teflon, polyester and the like.
In addition, activated carbon or charcoal may be used or the filter
media itself may be impregnated with diatomaceous earth or any
other filter aide powder known to those skilled in the art.
Finally, the filter bags may be pleated paper, synthetic or felt
material or felt cloth or a ceramic material as will be obvious to
those skilled in the art.
[0016] Accordingly, it is an object of this invention to provide a
continuous filtering system for deep fat fryer which utilizes a
sump disposed adjacent the fryer wherein surface oil continually is
drawn into the sump and into a filter therein. The filter retains
sediment from the oil, and the filtered oil is then drawn from the
sump and recirculated into the deep fat fryer.
[0017] It is another object of this invention to provide a deep fat
fryer with a highly efficient heating system for the oil bath which
utilizes a "U" shaped heat tube extending through the bath with
internal baffles to provide a spiraling circulation of combustion
gases and a plenum disposed below the bath to heat the interior and
lower portion of the bath on a continuous basis.
[0018] It is a further object of this invention to provide an
efficient deep fat fryer which will both efficiently maintain an
oil bath at a desired temperature, and continuously remove food
products from the surface of the bath before the food products
absorb sufficient oil to settle to the bottom so that the food
particles are rapidly removed as they accumulate in the bath,
minimizing the opportunity to impart undesirable flavors to the
bath.
[0019] It is yet another object of this invention to provide unique
filter bags for filtering hot cooking oil wherein the bags are of a
porous material having an open top and opposed shoulder portions
for receiving a metal clamp plate at the top thereof so that the
bags can be lowered into a sump by the metal plate and raised from
the sump by the same support, and whereby the bags may be disposed
of merely by removing the metal support from the respective
shoulder portions of each bag.
[0020] These and other objects will become readily apparent with
reference to the drawings and following description wherein:
DETAILED DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a front view of the deep fat fryer of this
invention.
[0022] FIG. 2 is a side view of the deep fat fryer of this
invention.
[0023] FIG. 3 is a top view of the deep fat fryer of this
invention.
[0024] FIG. 4 is a schematic view showing oil circulation within
the deep fat fryer of this invention.
[0025] FIG. 5 is a side view of the heat tube used in the deep fat
fryer of this invention.
[0026] FIG. 6 is a cross-sectional view taken along lines 6 6 of
FIG. 5.
[0027] FIG. 7 is an end view of the heat tube of FIG. 5.
[0028] FIG. 8 is a top view of the baffle plates used in the heat
tube of FIG. 5.
[0029] FIG. 9 is a fragmentary prospective view looking downwardly
into the deep fat fryer of this invention.
[0030] FIG. 10 is a prospective view of the sump filter system for
the device of this invention.
[0031] FIG. 11 is a prospective view of a filter bag from the
filter system of FIG. 10.
[0032] FIG. 12 is a prospective view of the metal support plate
used in combination with the filter bag of FIG. 11.
[0033] FIG. 13 is a fragmentary assembled view of the filter bag
and support plate of FIGS. 11 and 12; and
[0034] FIG. 14 is a prospective view of hand held device to raise
or lower the filter system from the sump in the device of this
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0035] With attention to the drawings and to FIGS. 1 and 2 in
particular, the deep fat fryer 10 of this invention includes a
front portion 12 mounting controls 14 within a housing 16 having
access doors 18 and having a wheeled oil container 20 disposed
therebelow.
[0036] FIG. 2 is a right side view of the deep fat fryer 10 of this
invention showing the housing 16, the wheeled hot oil container 20,
and in phantom, the fryer tank 22, filter sump 24, burner tube 26
and an internal flue 28 which could be connected to an external
flue (not shown).
[0037] With reference to FIGS. 2, 3 and 4, the tank 22 mounts
cantilever style the burner tube 26 which consists of a "U" shaped
conduit having a conventional burner blower combination 29 mounted
at an end 30. Burner tube 26 is also mounted cantilever fashion at
end 30 to the left side wall 32 of the fryer tank 22. Combustion
gases in burner tube 30 travel toward the return section 34 and
then return along leg 36 to be expelled downwardly in elbow 38 to a
plenum 40. The exhaust gases circulate through plenum 40 into a
flue 28. As will be obvious to those skilled in the art, baffle
plates (not shown) are disposed in plenum 40 to improve heat
transfer between the hot combustion gases passing therethrough and
the bottom of tank 22. The burner tube 26 is mounted cantilever
style from the left side wall 32 so that as the burner tube heats
expansion will not effect the tube mounting.
[0038] With attention to FIGS. 5-8, the burner tube 26 is intended
to convey the gases of combustion from the burner 29 in a spiraling
fashion. It was discovered that when the combustion gases pass
through the tube 26 in a spiraling fashion, excessive heat is not
produced in the return section 34. In the conventional burner tube,
wherein the return section is a substantially square corner,
excessive heat is a problem and requires more expensive heat
resistant construction materials. The spiraling effect of the gases
passing through burner tube 26 is enhanced by baffle plates 42
disposed in the legs of burner tube 26. The baffle plates
essentially are disposed at an acute angle to the axis 44 of the
burner tube 26, and have central holes 46 therein to facilitate the
passage of the combustion gases. The baffle plates 42 create a
turbulator effect within the burner tube 26 whereby not only are
the combustion gases swirled as they pass therethrough, but heat
transfer therefrom is facilitated by conduction from the baffle
plates 42 to the walls of the burner tube 26.
[0039] With reference to FIG. 4, during normal operation, food to
be cooked is disposed in a basket 50 which is lowered into the tank
22. Hot oil 52 from within the tank continuously overflows into the
sump 24 where it is filtered in a filter assembly 54. A second
filter (not shown) can be disposed at the outlet 56 of the sump 24
so that if an inexperienced operator permits food to fall into the
sump, it will not circulate to the pump 58. A suction pump 58
normally returns the filtered oil to the tank 22 through a jet tube
60 disposed within the tank along a wall opposite the sump. Jet
tube 60 is intended to be disposed adjacent the upper portion of
the burner tube 26 to facilitate the circulation pattern shown in
FIG. 4.
[0040] It has been discovered that this structure including the
circulation pattern facilitates the rapid removal of dislodged
pieces of food to be cooked from basket 50 into sump 24 so that
they can be filtered from the system before undesirable flavors are
imparted to the oil bath 52.
[0041] As also shown in FIG. 4, the conduit system for normal
operation uses a valve system 62 and 64. Valve 64 is normally
closed, but it can be opened if it is desired to use pump 58 to
supply oil from the oil container 20. As will be obvious to those
skilled in the art, conventional means can be used to drain the
tank 22 into oil container 20 by gravity, or by a pump system (not
shown).
[0042] Concerning the filter system, sump 24 preferably mounts a
pair of mesh baskets 70 as shown in, for example, FIGS. 9 and 10.
Mesh baskets 70 typically are tapered inwardly toward the bottom
and are held in place by a collar 72 which has a pair of eyes 74 to
facilitate removal thereof from the sump 24 as will be subsequently
explained.
[0043] With reference to FIGS. 11-13, each mesh basket 70 is
intended to receive a cloth filter bag 80 supported by a metal
clamp plate 82 which in turn mounts a pair of eyes 84. As shown in
FIG. 13 each filter bag 80 is supported on clamp plate 82 by
shoulders 86 integral with a bag 80 and an opening 88 is provided
in plate 82 for oil to be filtered to be admitted to the interior
of bag 80. The preferred embodiment of this invention shows a pair
of mesh baskets 70 which would be intended to each receive a filter
bag 82. Filter bags 82 are tapered towards the bottom 90 so that
when suspended as shown in FIG. 13, they will easily fit within the
basket 70 and because the bags 80 are cloth, they will be self
aligning within the basket 70.
[0044] FIG. 14 shows a gripping member 94 which has a pair of hooks
96 and is intended to be gripped at the handle portion 98. Hooks 96
are intended to be received in eyes 84 so that the bag 80 can be
raised and lowered by hand from basket 70. Similarly, hooks 96 can
be received in eyes 74 so that the basket assembly 70 shown in FIG.
10 can be raised from the sump 24 for cleaning or the like.
[0045] While the preferred embodiment of the filter of this
invention uses a pair of cloth bags, and the cloth is preferred to
be a sateen weave 96.times.60 (Pic per inch), of 100% virgin
cotton, 9.7 oz., with the sateen side in and an air permeability of
15-20 CFM. Other types of materials can be used either disposable,
re-usable, or re-usable for only a relatively small number of
times. For example, the bags may be made of paper with or without a
synthetic mix and the synthetic materials could be rayon, nylon,
Teflon, polyester or the like. Furthermore, felt cloth, paper or
screen and the like either of synthetic, or paper materials could
be used and ceramic materials could be used. The media used in the
filter could be impregnated with diatomaceous earth or other
filtering products as desired. Finally, the filter could be a metal
mesh perforated metal, or porous sintered type of metal instead of
a disposable or re-usable cloth, paper, or the like.
[0046] In addition, in the preferred embodiment of this invention
the shoulders 86 are provided to accept the ends of the clamp plate
82 to thereby support the filter bag. This invention, however, is
not intended to be limited to that specific design and any
conventional means for attaching the filters to a support so that
the filter can be removed from the sump is intended to be included
as part of this invention.
[0047] During operation, when the vacuum at the suction pump 58
reaches a predetermined point, a gauge and/or sensor (not shown)
will activate a signal indicating to an operator that the system
should be shut down and filter bags 80 replaced. In that event, the
bags can be withdrawn with member 94 from the baskets 70, and
disposed of. New bags 80 can then be quickly mounted on clamp plate
82 and the composite returned to the basket assembly 70 so that the
system can be restarted.
[0048] In summary, the efficient deep fat fryer system of this
invention maximizes the heat exchange from a gas burner by using a
cantilever mounted "U" shaped burner tube which extends through the
tank of cooking oil. The burner is intended to admit products of
combustion in a swirling fashion and the swirling fashion
facilitated by baffle plates disposed within the "U" shaped burner
tube. Because of this spiraling circulatory passage of gases
through the tube, the return section at the end opposite the
burner, does not need to be of extraordinary heat resistant
material. Without the swirling effect of the products of
combustion, the burner would admit a jet thereof directly against
the return section wall, and that wall then would require heat
resistant material to avoid deterioration and negatively affect oil
life. The gases from the burner travel through the burner tube and
exit therefrom into a plenum below the tank wherein further baffle
plates may be used to facilitate heat exchange with the combustion
gases before they are expelled from the plenum through a flue. The
burner system of this invention is intended to operate on at least
two different modes. A low fire mode is provided to reduce the
component cyclical wear and for melting solid shortening. A sensor
control is also provided so that when the cooking oil in the tank
reaches a predetermined temperature the burner will change to a
high fire mode wherein both the burner and the blower associated
therewith provide an enhanced heat exchange with the oil in the
tank until it reaches a cooking temperature. The control system for
this invention then contemplates a return to a low fire mode of
operation so that the burner is continually on during the cooking
process but cycles to a high fire mode when necessary due to
temperature changes within the cooking oil. The control will
activate the pump filter system automatically once a predetermined
temperature is reached.
[0049] As an alternative the burner can operate intermittently
wherein it fires each time sensors call for heat to the tank and
once a flame is present the burner goes to the high fire mode for
the duration of the burn.
[0050] The deep fat fryer of this invention further utilizes an
improved filter circulatory system wherein a sump is provided
adjacent the upper portion of the tank so that cooking oil
continually overflows into the sump and it passes through filter
bags to remove entrained sediment therein. The filtered cooking oil
is then recirculated by a suction pump to a jet tube disposed
opposite the sump on the side of the tank and the filtered cooking
oil is injected into the tank. It is intended that this filter
system will operate to remove dislodged food particles primarily
from the surface of the tank before they have sufficient time to
absorb cooking oil and settle to the bottom thereof. By rapidly
removing any food particles which dislodge from the food being
cooked, the likelihood that such particles will impart undesirable
flavors to the cooking oil is minimized.
[0051] The preferred filter bags of this invention are intended to
be of 100% virgin cotton cellulose material (unbleached) and are
intended to be re-usable or disposable. Each bag is tapered
downwardly to facilitate raising and lowering it from its
supporting basket, and each bag has a corresponding shoulder
thereon at the top for engagement with a flat support plate of
metal. The metal plate then would be reusable whereas the bags
would be discarded when they are filled with sediment.
[0052] To facilitate efficient filtering the bag must preferably be
9.7 oz. sateen weave, 96.times.60 (pic per inch) with air
permeability of 15-20 CFM. It was found to be desirable for
efficient filtering that the sateen side of the bag is inside.
[0053] It will be readily seen by one of ordinary skill in the art
that the present invention fulfills all of the objects set forth
above. After reading the foregoing specification, one of ordinary
skill will be able to effect various changes, substitutions or
equivalents and various other aspects of the invention as broadly
disclosed herein. It is therefor intended that the protection
granted hereon be limited only by the definition contained in the
appended claims and equivalents thereof.
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