US2430329A - Display refrigerator including controls for the operation thereof - Google Patents

Description

Nav. 4,- 1947. A R. E. DAvls 2,430,329

DISPLAY REFRIGERATR INCLUDING conTRoLs Fon 'rma OPERATION THEREOF Filed July 3o, 1945 2 sneets-sne'et 2 /M/En/roe."

:S K C/ ,g-- @www A Patented Nov. 4, 1947 2,430,329' UNITED STATES PATENT ori-'ics DISPLAY REFRIGEBATOB INCLUDING N- TROLS FOR THE OPERATION THEREOF Russell E. Davis, St. Louis, Mo., assigner to Huasman-Ligonier Company, St. Louis, Mo., a corf poration of Delawarev Application July 30, 1945, Serial No. 607,8 11V `6 Claims. l

This invention relates to improvements, in refrigerated food display cases of the kind shown in my copending application Serial No. 547,385 wherein sub-zerou temperatures are maintained in the continuously open self-service food display chamber of the case by a closed thermosiphon system of refrigerated air produced by a. refrigerating circuit including expansion coils located in the display chamber and an upper chamber in communication therewith and a condensing unit common to both expansion coils, and the upper expansion coil is defrosted by an electric heater which is turned on when the condensing unit stops and is turned ofi' when the condensing unit starts.

The present invention has for its principal objects to preserve all of the advantages of the above type of refrigerated display case and, at the same time, provide for automatically turning on the defrosting heater and stopping the condensing unit at a predetermined time, eliminate the electrically operated refrigerant valve heretofore employed and attain other advantages hereinafter appearing. The invention consists in the refrigerated display case and in the parts and combinations and arrangements of parts hereinafter described `and claimed.

In the accompanying drawings which form a part of this specicaton and wherein like symbols refer to like parts wherever they occur,

Fig. 1 isa front elevational view of an opentop, self-service refrigerated display case embodying my invention,`

Fig. 2 is an enlarged vertical cross sectional view through said case in line 2-2 in Fig. 1; and

Fig. 3 is a diagrammatic View illustrating the refrigerating circuit and the electric control circuit for said refrigerating circuit and the defrosting heater therefor.

In the accompanying drawings my invention is shown embodied in an open-top, self-service refrigerated display case of the type shown in my copending application Serial No. 547,385, wherein the display case comprises a top wall I, a bottom wall 2, a relatively high rear wall 3, a relatively low front wall 4 and end walls 5. As shown in the drawings, the top wall I extends from the rear wall 3 of the case and terminates short of the front wall 4 thereof in a depending baille or curtain wall 6 that extends below the level of the top edge of the front wall 4. The above described arrangement of walls provides a lower food storage and display chamber A with an access or reach-in opening `A1 in thetop thereof between the iront wall 4 and the baille wall 6, and an' upper chamber B communicating with the upper portion of said food chamber rearwardly of said access opening. As shown in the drawings, a sealed multi-pane glass panel 4a constitutes the upper portion of the low front wall `l of the case; and sector-shaped glass panels 5a constitute the upper portions of the end walls 5 of said case between said front wall and thel baille wall 6. lA suitable light, such as fluorescent tubing 1a, is mounted in a suitable wiring conduit, shade and reiiector 1, which is secured to the front face of the bafe wall 6 hush with the upper surface of the top wall I;-`and an inclined mirror 8 inclines downwardly and rearwardly :from said conduit to said baille wall.

The hereinbefore described display case is provided with a mechanical refrigerating apparatus of the compressor-condenser-expander type. As illustrated in the diagram shown in Fig. 3, the refrigerating circuit comprises a suitable condensing unit C, including the usual compressor Il and electric driving motor 9a, and driving belt connection 9b therebetween condenser Ill and liquid receiver II therefor. The refrigerating circuit also includes a suitable heat exchanger I2, a suitable throttle or expansion valve i3, and evaporators or expanders in the form of a iintype cooling coil I4 and a series oi plate type cooling coils l5. The refrigerant ows from the compressor 9 to the receiver II through the condenser IIl, thence from the receiver to the heat exchanger `I2 through a conduit I6, thence from the heat exchanger to the expansion valve I3 through a conduit I8, thence from the expansion valve to the iin coil I4 through a conduit Ilia, thence through a conduit lbto the plate coils I5 and connecting conduits i9 therefor and thence from the plate coils and through the heat exchanger back to the compressor through a return conduit 2l. As shown in the drawings, the 1in coil i4 is located in the upper portion of the rear upper chamber B of the food case and extends longitudinally thereof suhstantially from end to end thereof, while the plate coils I5 are mounted on edge in the cold storage food display chamber A in spaced apart relation 'so as to form bins 22 therein that preferably extend from front to backthereof. As shown in Fig. 2each of the plate coils I5 comprises a. sealed casing I5a containing a flat cooling coil ISU and a suitable eutecticsolution I5c which surrounds said coil and has a relatively low freezing point.

Mounted in the rear upper chamber B of the case immediately below the iin coll ll therein are drains o r gutters 23 for receiving and carrying away moisture that drips from said coil. The gutters 23 extend longitudinally of the `iin coil from end to end thereof and kare inclined from one end to the other so as to discharge into a suitable drain pan 24 mounted in said chamber below the discharge end of said gutters. As shown in Fig. 2, a vertical bailleor partition wall 25 extends from end to end of the upper chamber B of the case beneath the nn coil Il therein substantially midway between the rear wall 3 and the baille wall 6 with its upper edge fixed to the under side of one of the gutters 23 and with its lower edge disposed in the lower display chamber A slightly below the level of the lower edge of said baille wall. The partition or baille wall divides the portion of the upper chamber below the iin coil Il therein into vertical front and rear flues 25 and 21, respectively. 'I'he rear upper chamber B is provided with means for rapidlyl defrosting the fin type cooling coil I4 therein, said means comprising an electric heater preferably in the form of electric resistance wires or cables 23 secured to the undersides of the gutters 2l forreceiving the liquid condensate from said cooling coil.

As shown in Fig. 3, the compressor motor 9ais operated by a, 220 volt electric circuit 23 which is normally opened and closed by a suitable thermostatic switch 3l having a feeler bulb 3| located in the lower food display chamber A adjacent to or in thermal contact with the plate coils I5 therein. The defrosting heater 23 is operated by a normally open.110 volt electric circuit 32. A time controlled switch D has a pair of contacts 33, 33a, which open and close one side of themotor circuit 23, and a pair of contacts 3l, 34a, which open and close the heater circuit 32. The contacts 33 and 3l are fixed one on each side of a -hinged or pivoted arm'35 for movement therewith into and out of engagement with the stationary contacts 33a and 34a respectively. A spring 36 yieldably holds the contact 33 in engagement with the contact 33a, to thereby close the motor circuit 25, and with the contact 3l out of engagement with the contact 34a so as to open the heater circuit 32. Thus, the contacts 33, 33a in the motor circuit 23 are closed when the contacts 34, 33a,in the heater circuit 32 are open and vice versa.

The time switch D also includes electrically controlled mechanism adapted at a predetermined time to actuate the contact carrying lever 35 to open the motor circuit 23 and close the heater circuit 32. 'I'his mechanism preferably comprises an electric clock 31, which is connected through wires 33 to heater circuit 32 for continuous operation thereby, a shaft 39 driven by said clock, a driving disk III xed to said shaft, and an edge cam 4I xed to said driving disk and in continuous edgewise contact with a laterally bent free end portion of the hinged contact carrying arm 35 so as to operate said arm whenever the rise lla of said cam moves into engagement with the laterally bent free end portion of said arm. As shown in the drawings, the cam 4I is secured to the cam disk 4l by means of a screw 43 `which extends through an arcuate slot 42 in said cam and is threaded into said disk, thus permitting said rotational adjustment of said cam relative to said disk to vary the time of operation of the switch D. The cam 4I makes one complete revo1ution,'say once every 24 hours; and the circumferential length of the rise lla of said cam determines the length of time that the contact arm 35 is held Ain motor circuit opening and heater circuit closing position during each complete revolution of said cam. As shown in Fig. 3 the time controlled switch D and the thermostatic Switch 3l may be enclosed in a common housing 4I.

v As indicated by the ilow arrows in Fig. 2, when n the 'r'efrigerating circuit is operating to reduce the display chamber temperature to the desired subzero level there is a continuous circulation of refrigerated air downwardly from the upper iin coil cooling unit Ilthrough the ue 21 into the 4 lower display chamber A and a return iiow of said air from said display chamber to said upper iin coil unit through the ue 25. The baille curtain wall 6 of the case extends below the level of the top edge of the front wall 4 thereof and thus permits the refrigerated air in the open top display chamber A to rise above the lower edge of said curtain wall and this height, plus the atmospheric pressure exerted on the display space opening A1, balances the weight of the refrigerated air in the sealed Space back of said curtain wall and forms in said opening a layer 43 of stratified or dead insulating air which tends to prevent the escape of the refrigerated air therethrough.

When the refrigerating apparatus is operating, the motor circuit 23 is closed by the thermostatic switch 33 and the time switch D and the heater circuit 32 is opened by said time switch, thus putting the refrigerating apparatus into operation zo and rendering the defrosting heater 28 inoperative. During the operation ofthe refrigerating apparatus, liquid refrigerant passes from the liquid receiver II of the condensing unit C through the conduit I5, heat exchanger I2, conduit I8, ex-

u pansion or throttle valve I3, conduit I8a into the upper iin type' expansion coil I3 and thence through the conduit Ib into the lower plate type expansion coils I5. The liquid refrigerant, after evaporating and absorbing heat in the expansion o coils Il and I5 is then converted into vaporized refrigerant which is returned to the condensing unit C through the conduit 2|, heat exchanger' I2 and again converted into liquid form in said condensing unit and again returned to the receiver 35 I I thereof.

When the temperature in the lower display chamber A of the case reaches a predetermined low level, the thermostatic switch 30 is opened, /thereby opening the motor circuit 29 and stopping the`condensing unit C and the ow of refrigerant therefrom through the refrigerating system. JWhen the display chamber temperature rises a few degrees above the desired predetermined low level, the thermostatic switch 30 again closes the 45 motor circuit 29 and puts the refrigerating appaing can be set for the most opportune time of the day or night. For instance, the time switch .may be set to bring about the defrosting in the early morning hours when the store is cool and there is no activity therein so as to minimize dangerous temperature fluctuation. When the time for defrosting arrives, the rise lla on the clock operated cam 4I moves into engagement with the free end of the contact carrying arm 35 and operates the latter against the tension of the spring 36, thus separating the contacts 33, 33a and rendering the refrigerating apparatus inoperative and engaging the contacts 34', 34a and Vstarting the defrosting heater 28..- The rise lla of the cam 4I remains in contact with the contact carrying lever 35 for a period of time sumwill engage the contacts 33, 33a and again place the thermostatic switch 30 and disengage the f contacts 34, 34a and cut olf the'defrosting heater.

An important advantage of the above described arrangement is that it eliminates the electrically operated valve heretofore used in the liquid line ofthe refrigerating system and renders the refrigerating system directly responsive to temperaturerequirements in the food display'chami ber. Another advantage is that it eliminates the numerous temperature iluctuations which occur when the defrosting heater is turned on during each cycleof the refrigerating system and thus prevents the display chamber frombeing subjected to abnormal temperatures during each refrigerating cycle. V

Obviously, the hereinbefore described open-top self-service low temperature refrigerating display case admits of considerable modification without departingfrom the invention. Therefore, I do not wish to be limited to the precise arrange-' ments shown and described.

What I claim is:

1. A refrigerated display case having a food chamber and a second chamber in continuous communication therewith, and a compressorcondenser-expander type refrigerating apparatus including an electric motor for operatingv the compressor, anexpansion coil in said food chamber and an expansion coil in said second chamber, an electric control circuit for said motor including a thermostatic switch responsive to temperature conditions in said food chamber only for starting and stopping said motor, an electric heater in said second chamber for defrosting the expansion coil therein, an electric control circuit for said heater, and a time switch associatedy with V 4. A refrigerated display case having a food chamber and a second chamber in continuous communication therewith, and a refrigerating apparatus' of the compressor-condenser-expander type including an electric motor for operating the compressonan expansion coil in said food chamber andan expansion coil in said second chamber, an electric control circuit for/,said motor including a thermostatic switch responsive to temperature conditions in said food chamber only for both starting 'and stopping said motor, an electric control circuit for said heater, and a time controlled. switch associated with both circuits for opening the motor circuit and `closing the heater circuit at predetermined times.

5. AA refrigerated display case having a food chamber and a second chamber communicating therewith, and a refrigerating apparatus of the compressor-condenser-expander type including an electric motor for operating the compressor,

an expansion coilin said food chamber and an Y expansion coil insaid second chamber, an electric control circuit for said motor including a thermostatic switch responsive to temperature in rsaid heater circuit, and time controlled means said motor and heater circuits for opening said motor circuit and closing said heater circuit and vice versa at predetermined times.

2. A refrigerated display case having a lower food chamber with a continuously open access opening in the top thereof and an upper chamber in continuous communication with said lower chamber below the top thereof and rearwardly of the access opening therein, and a compressorcondenser-expander type refrigerating apparatus including a motor for operating the compressor, a iin-type expansion coil in said upper chamber and a plurality of plate-type expansion coils ar- 'ranged' in spaced relation in said lowerchamber.

to form bins therein, an electric heater in said upper chamber for defrosting the expansion coil therein, an electric control circuit for said motor including a thermostatic switchl responsive to temperature conditions in said lowerv chamber only for starting and stopping said motor, an electric control circuit for said heater, and a time controlled switch associatedwith both circuits and -operable at predetermined times to close 'said heater circuit and open said motor circuitand viceversa. l

3. A refrigerated case. having two communicating chambers and asingle refrigerating apparatus including expansion coils in the respective chambers, control means responsive to temperature conditions inone chamber only for both starting and stopping the' operation of said refrigerating apparatus, a heaterfordefrosting the expansion coil in the, other of said chambers, and means operable at predetermined times for turningon said heater and for preventing the starting of said refrigerating apparatus by said temperature responsive control means.

` Number Name Date 2,073,008 v Haschke Maxz 9, 1937 2,196,291 Clancy .l Apr. 9, 1940 for'openingthe contacts in said motor circuit and for closing the contacts in said heater circuit.

6. A refrigerated display case having a food chamber and a second chamber communicating ltherewith, and a refrigerating apparatus of the compressor-condenser-expander type including an electric mot'or for operating the compressor,VV

'mostatic switch responsive to temperature con-- 45- ditions in saidV food chamber only for both starting and stopping said motor, an` electric control circuit for said heater, and a switch associated with both circuits for opening the motor circuit and closing the heater circuit at predeterminedtimes, said switch including a pair of normally closed contacts located in said motor circuit, a pair of normally open contacts disposed in said heater circuit, and time controlled means for opening the contacts in said motorcircuit and closing the contacts in said heater circuit, said lastmentioned means comprising a pivotal arm supporting onevoi" the contacts of each pair for movement into and out of engagement with the other contact thereof, a rotary cam for actuating said arm, and an electric clock for rotating said cam.

RUSSELL E. DAVIS.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PA'I'ENTS 2,327,355 Kleist Aug. 24, 1943

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