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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to enclosed machines for preparing food
commercially in small quantities and, more particularly, relates to
heatable containers in such machines.
Many kinds of sellers of prepared foods at retail are faced with providing
such food in quantities small enough for a single serving. Various kinds
of stand-alone food preparation machines have been developed for providing
prepared food in single serving quantities.
Among the kinds of these machines which have been developed is a food
preparation machine for the deep-fat frying of food in quantities for one,
or a few, servings. Such machines can be used to prepare french-fried
potatoes, fish pieces, chicken pieces or the like.
A machine for doing this is shown in FIG. 1. There, two baskets, 10, are
shown which can be filled with such kinds of food as are desired to have
fried in cooking oil. A motorized transport mechanism can be activated to
lower baskets 10 into a container or vat, 11, of cooking oil. Most of the
motor parts for the transport mechanism, the motor control circuitry, and
other control circuitry, can be mounted and contained in a box, 12, shown
in the interior of the machine in FIG. 1. Controls for operating the
machine can extend through one of the panels enclosing the machine on the
right-hand side thereof. Shown above these controls is a fire extinguisher
provided as a safety measure and directed into the interior of the
enclosure formed by the outer panels of the machine.
During operation, some oil is splattered about and, in any event, the oil
ages during use, and so, certain residues accumulate on container 11. This
necessitates the changing of the oil in, and the cleaning of, container
11.
Heretofore, the containers used as a container 11 were operated with a
molded-in heating element affixed thereto. During cleaning operations
where the use of a solvent cleaner was resorted to, as is necessary after
awhile, the solvent in many instances gets into the heating elements
inside the molding in the casting. This leads to either shorting out the
heating elements, or the burning out of them, necessitating discarding of
the entire container with the failed heater. Furthermore, various other
components in such configuration were mounted directly to the container
necessitating a time consuming and inconvenient effort to remove them
before cleaning or otherwise risk their damage also in the cleaning
process. An arrangement for providing heaters and other components would
be desirable where they could all be removed to permit cleaning of the
container alone.
SUMMARY OF THE INVENTION
The present invention provides a support cover with heaters and other
elements mounted thereon which can be fastened to the container by
removable fasteners to permit removing the heater and other elements as a
single assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows generally an enclosed food preparation machine for deep fat
frying;
FIG. 2 shows an exploded view of the heatable container assembly of the
present invention;
FIG. 3 shows another view in cross section of this same assembly;
FIG. 4 shows yet another cross section view of this assembly; and
FIG. 5 shows a schematic circuit diagram of some aspects of the electrical
system used with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 2 shows an exploded view of a heatable container assembly which can be
removed as a unit from the food preparation machine. Container 11, shown
at the top of the view, is a container formed of cast aluminum bottom and
side walls with two threaded studs, 13, projecting from bosses in, or
affixed to, the casting. These bosses are located in a recessed space to
accommodate a heater, 14. The surface of this recessed space, 15, is the
heating surface of the container against which heater 14 is placed with a
similarly flat surface to provide heat to the contents of the container.
Another recess in front of this heating surface forms a sensing surface,
16. Against this surface are forced two thermostatic switches, 17 and 18,
this forcing being provided by springs, 19. Springs 19 are affixed to the
bottom of each of switches 17 and 18 by an interface bracket, 20, and a
pin, 21. The other ends of spring 19 are fixed to a formed stainless steel
sheet serving as a support cover, 22. Support cover 22 has two bosses, 23,
which fit within springs 19 where they are pinned with further pins, 24.
Heater 14 is affixed to support cover 22 by two pan head screws, 25. Also
affixed to support cover 22 is an interconnection wiring harness, 26.
Harness 26 has one member, 27, of an insertable plug set pair electrically
connected to one end thereof. Slide clip terminals are used on the
opposite ends of the wires in harness 26. A wiring bracket, 28, and its
associated screw and nut affix the wire harness to cover 22. Further shown
are a pair of interconnecting wires, 29, having slide clip terminals on
either end thereof.
The support cover assembly comprises everything shown in FIG. 2, other than
container 11, and all these parts other than cover 22 are assembled to
support cover 22. This support cover assembly can then be fastened to
container 11 through holes in the support cover which permit threaded
studs 13 to pass through cover 22. Support cover 22 is then held in place
by threaded nuts, 30, which can be threaded onto studs 13 over support
cover 22. Thus, the removal of threaded nuts 30 from studs 13 permits the
separation of the entire support cover assembly from container 11.
Thereafter, container 11 can be immersed in a solvent, or scrubbed by a
solvent, without concern for the heater, thermostatic switches or other
components mounted on support cover 22 coming under attack by the solvent.
Note that heating surface 15 and sensing surface 16 are each recessed in
the bottom wall of container 11. This improves the heat transfer through
surface 15 for heating the contents of container 11, and improves the
accuracy of the sensing at sensing surface 16 by thermostatic switches 17
and 18 because of the relative ease of heat transfer therethrough. The
upper surface of heater 14 fits in the recess against this similarly flat
heating surface 15 to provide for good thermal transfer from heater 14 to
container 11. On the other hand, support cover 22 is formed so that a
center portion supports all of the components except heater 14. Instead,
heater 14 is mounted by threaded screws 25 on a couple of support cover
flats which are above the bottom surface of cover 22. These raised flats
result in a space between most of cover 22 and heater 14 to thereby reduce
heat transfer to cover 22 from heater 14.
The cross-sectional views in FIGS. 3 and 4 show this arrangement more
clearly. The cross-section view in FIG. 3 is taken through a portion of
the sensing surface just behind the forward facing wall of container 11 in
FIG. 2. The cross-sectional view in FIG. 4 is taken inside the left-hand
wall of container 11 as shown in FIG. 2 with the wiring eliminated to make
this view clearer. From these views, heater 14 can be seen in the recess
in the bottom wall of container 11 having its upper heating surface flush
against the heating surface 15 in the recess of the bottom wall of
container 11. Thermostatic switch 17 can be seen flush against sensing
surface 16 of container 11.
FIG. 5 shows the schematic electrical diagram of the electrical circuitry
used in operating heatable container 11 in the food preparation machine of
FIG. 1. A 120 V plug, 31, accepts alternating voltage and current for the
remaining circuitry. A first safety switch, 32, is part of the fire
extinguisher apparatus. A second switch, 33, is a double pole switch
serving as the on-off switch in controlling the food preparation machine
after plug 31 is plugged into a source of alternating voltage. One pole,
34, of switch 33 provides electrical power to the heating circuitry. The
other pole, 35, provides power for the remaining portions of the
circuitry. The use of two poles eliminates having the large current drawn
by the heating circuitry flow through the same switch contacts as the
current drawn to operate the remainder of the circuitry.
Heater 14 is chosen as an electrical resistance heater and, in FIG. 5, is
provided in series with primary thermostatic switch 17 and
over-temperature thermostatic switch 18. An over-temperature indicator
light, 36, is shown in parallel across over-temperature switch 18 so that
the opening of over-temperature switch 18 leads to light 36 being switched
on. Primary thermostatic switch 17 is set to open at temperatures greater
than 385.degree. F. and over-temperature switch 18 is set to open at
temperatures above 395.degree. F.
This series combination is connected to the alternating voltage supplied
through plug 31 and switches 32 and 33 by relay control switches, 37 and
38. Electrical power to operate the relay solenoid is provided through
switch 33 and pole 35 which is also provided to other alternating voltage
operating components indicated in FIG. 5 as a group within a box
designated 39.
The electrical power to operate the relay is applied to a step-down
transformer, rectifier and voltage regulator indicated as group by a box
designated 40. Box 40, thus serving as a direct voltage source of a value
of 12 V between its output terminals, supplies electrical power to other
direct voltage operated components indicated as a group in a box
designated 41 in FIG. 5. The voltage is also applied to three safety
switches, 42, 43 and 44, and then the coil, 45, of a relay. The relay
comprises coil 45 and solenoid operated switches 37 and 38.
Electrical power is always supplied to coil 45 to hold switches 37 and 38
closed upon the supply of alternating voltage by a plug 31 unless any of
safety switches 42, 43 or 44 open (or safety switch 32 or on-off switch
33). Switch 42 is an air temperature thermostatic switch sensing air
temperature in the cooking chamber, and will open if that air temperature
exceeds a set value. Switches 43 and 44 are magnetic switches, which open
in the absence of magnetizable metal in the proper positional relation to
them. These switches are placed within the food preparation machine to
assure that the heater 14 cannot heat if the front cover has been removed
from the machine or if the container 11 is not in its place.
Thus, heater 14 will heat continually if everything is normal once the plug
31 has a voltage applied thereto and on-off switch 35 is closed. Heating
will continue until the temperature sensed by switch 17 exceeds
385.degree. F. at which time that switch will open to discontinue heating
until the contents of container 11 have sufficiently cooled to allow
switch 17 to again close. Any failure of switch 17 will lead to a similar
action for switch 18. As a result, once operation of the food preparation
machine is decided upon by its operator, cooking oil in container 11 will
be kept at a temperature of approximately 385.degree. F. until the machine
is switched off.
The circuit portions shown within the dashed line box designated 46 are the
circuit portions shown in FIGS. 2 and 3. That is, the circuit components
mounted on support cover 22, and the wiring therefor, are represented in
electrical schematic form by the diagram portion contained within dashed
line box 46.
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