US 2418671 A
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Description (OCR text may contain errors)
April 8 1947; s. M. s cHwELLER 2f/18,6711l v RESTRICTOR DEVICE FOR RERIGERATING APPARATUS 'Filed Dec. 26, 1944 YSYA warn. Se/mm uk.
Patented Apr. 8, 1947 BESTRICTOR DEVICE FOB REFRIGERATING v APPARATUS Sylvester M. Schweller, Dayton, Ohio., assignor to General Motors Corporation, Dayton, Ohio, a
corporation of Delaware l Application December 26, 1944, Serial No. 569,682
2 Claims. l
This invention relates to refrigeratmg apparatus and particularly to air cooled refrigerating 4 apparatus of the household type. i
Due to simplicity in construction and the substantially fool proof characteristics of xed or continuously open restrictors, this type of restrictor has generally replaced movable valves heretofore employed in refrigerating systems for controlling the ilow oi liquid refrigerant from the condenser to the evaporator and for causing expansion of liquid refrigerant into the evaporator. While such flxd restrictors have been extensively used they present certain problems which the present inventionlsladapted to overcome;
In air cooled refrigerating apparatuses, particularly of the household type in which trays containing water to` be frozen are placed in the evaporator, the refrigerating mechanism operates emciently with the employment of a constantly open xed type restrictor in the system'at normal t room temperatures. However, this same refrigerator in either of diierent room temperatures of, say for example, 70 F. and 110 F. will not as the placing' of a plurality of Atrays contain.-
ing water to be frozen in the evaporator. In other words, a sharp heavy demand on the evaporator of an air cooled refrigeratingsystem, wherein a ilxed restrictor is employed, will not be eiectively met in a room maintained at either a low temperature or a high temperature be cause the fixed restrictor together with certain characteristics of the refrigerant liquefying and compressing unit limits maximum efciency perfomance of the system. In a low temperatured room the compressor unit operates with a low head pressure and with high vacuum low pressure. -In a high temperatured room the com.. presser unit operates with a higher head pressure and with a lower vacuum. AIn other words the pressure differential between the high and low pressure sides of the system is much greater at high room temperatures', than at normal room temperatures, and much lower at low room temrelatively long capillary flow conduit which is thermally responsive substantially throughout its entire length to condenser refrigerant temperatures and/or to condenser air temperatures to form a. compensator cooperating with the refrigerant expander or restrictor to provide the cor peratures. Consequently, if a iixed restrictor is template the use in a refrigerating system of a thermally responsive device and particularly a rect ilow of refrigerant under'varying roomrtemperatures.
An object of my invention is to provide a means particularly in a refrigerating apparatus employing a nxed or continuously open restrictor which Another object of my invention is to provide means for varying the ilow of refrigerant from a refrigerant compressing and liquefying unit of a refrigerating system to a xed or continuously open restrictor employed in the system so as to permit the proper amount of liquid-'refrigerant to flow through the restrictor at all times irrespective of ambient temperatures withln the room in which the refrigerator is located.
A further object of my invention is to provide a means for changing the cross-sectional area of a capillary passage in the liquid refrigerant supply line of a refrigerating system to vary the ilow of refrigerant to the expansion element or fixed restrictor which means is rendered eRective automatically in response to temperature changes. n
In carrying out the foregoing objects, it is a 1still further and ,more specic object of my in-n vention to provide a meansin the 'liquid refrigerant supply line of aY refrlgerating system which means is constructed of metals of different coelcient of Iexpansion and contraction and which means is provided with a continuously open sub stantially capillary passage the cross-sectional contour or area of which is" reduced and increased in response to an increase and decrease in temperature respectively for varying the flow of liquid refrigerant through the supply line.
Further objects and advantages of the present invention will be apparent from. the following description, reference being had to the accom panying drawings, wherein a preferred form of the present invention is/clearly shown.
In theA drawings:
Fig. 1 is a vertical sectional view of a refrigerating apparatus having a refrigerating system embodying my invention associated therewith;
Fig. 2 is an enlarged view of a compensating compartment I3. and liquefying unit comprises a sealed motor- ,compressor I4 for compressing refrigerant and o 3 device constructed in'accordance with my invention and which is interposed in the refrigerating systenr of the apparatus disclosed in Fig. 1;
Fig. 3 is an enlarged sectional view of a portion ofthe compensating device taken on the line 3-3 of Fig. 2; and
Fig.- 4 isA a view similar to Fig. 3 showing the area of the passage in the compensating device diminished.v
' prising a cabinet I0 having insulated walls Il forming a food storage compartment I2 therein and Aother walls forming a machine compartment I3 below the compartment. l2.` A closed refrigerant circulating system or circuit is associated with cabinet I and has its refrgerant compressing and liquefying unit mounted in the machine This refrigerant compressing for forwarding the compressed refrigerant under pressure to a condenser I5 wherein the compressed refrigerant is cooled, liqueed and. collected. From the condenser I5 the liquid refrigerant is forwarded through a supply line or conduit I8 to a restrictor |1 from where it is expanded into a cooling element or evaporator I8. 'I'he evaporator I8 is mounted in the upper portion of the food compartment i2 which is to be cooled. The evaporator I8 may be of the sheet metal variety and is provided with a refrigerated shelf I9 adapted to receive a .tray or trays containing water to be frozen into ice cubes or blocks as is conventional in the art. Vaporization of the refrigerant takes place in the evaporator I8 and the evaporated refrigerant returns to the compressor I4 through the suction line or conduit' 20.
(not shown) actuated in response to the refrigerating effect produced by evaporator I8 may be connected into the electric circuit leading to the motor-compressor I4. 'Ihe method of actuating such a switch by a thermostat bulb is conventional and lt is not believed necessary to describe same herein.
The restrictor I1 is of the fixed continuously or constantly opentype, well known in th'e art, and since the difficulties hereinbefore set forth arise with the use of this type of expansion ele-f ment or restrictor, it is desirable to employ in the refrigerating system some means for changing the effect produced in the refrigerating system in response to ambient temperatures. To this end I interpose in the liquid refrigerant supply line or conduit I8, adjacent condenser I5 and within the machine compartment I3, a. compensating means -thatwire 33 will be spaced therefrom throughout a substantial portion of the circumference thereof to allow ample expansion of the wire 33. The space between wire 33 and tube 34 togetherwith the U-shaped groove 38 forms a small or capillary passage of great length as compared to its crosssectionall area extending through the device 3| so as to communicate'with the interior of the refrigerant supply line or conduit I8 in which the device 3| maybe securely interposed. Wire 33 and tube 34, are formed of metal having a different coeiiicient of expansion and contraction relative to one another so as to be differently responslve to temperature changes. For example, the wire 33 may be formed of brass or aluminum while thev sleeve or tube 34 may be formed of stainless steel. The temperature of refrigerant vleaving the condenser and/or the temperature of yflow passageway extending therethrough.
The single passage in device 3| within the vline or conduit I6 may normally offer the proper resistance to control the flow of liquid refrigerant through this line. For example, flow of liquid refrigerant from the refrigerant compressing and liquefying unit to the restrictor I1, of the refrigerating system shown in Fig. 1, may be proper f at ordinary temperatures, maintained in a room in which the refrigerating apparatus is located,.
in accordance with the usual or normal pressures in the system. However, an abnormal rise in temperature Within the room, such as a period of several days of very hot weather and particularly at the time a large amount of water is placed in the evaporator to be frozen, will' cause thetemperature' and consequently the pressure of refrigerant in the condenser to increase. VWithout some means of controlling or varying the ow of refrigerant from the refrigerant compressing and liquefying unit too much liquid refrigerant will be forced from condenser I5 to and through restrictor I1 into the evaporator I8. My invention eliminates the diii'iculties hereinbefore pointed out in that when this abnormal high temperain the form of a restrictor device 3| (see Fig. 1).
The compensator or restrictor 3| is shown on a larger scale in Fig. 2 of the drawings and comprises asmall metal rod or wire 33 (see Fig. 3)
A enclosed in a metal sheet or tube 34.
The metal rod or wire 33 is slit longitudinally to .l provide a narrow substantially U-shaped groove 38 extending from end to end thereof. The tube 34 comprises a metal sheet wrapped around rod 33 with its edges 31 welded or brazed together to form a connning sleeve or the tube 34 for the rod. Tube 34 has aminor portion oi! its interior surface brazed or welded to rod or wire 33 as indicated by the heavy line 38 in the drawing which is .only slightly beyond the tube edges 31. diameter than the outside diameter of the wire so by refrigerant flowing to and througnthe passage .The tube 34 is normally of a larger inside cool pantry or the like, the compensating devicev or second restrictor 3| automatically offers less resistance to the ow of refrigerant into the evaporator and ample refrigerant is maintained in the evaporator to prevent 'the high suction force of the refrigerant compressing and liquefying unit from robbing or starving the evaporator of refrigerant and thereby the Aevaporator functions to effectively meet any demand placed upon it.
The temperatures are transmitted through walls of the device 3| from exteriorly thereof andvalso of the device. Due tothe confinement of rod or wire 33 within sleeve. 34 together. with the factanden that wire sa is welded to nie sleeve s4 only at its edges and slightly therebeyond and the difference vin ooeicient of expansion and contraction of in the system from circulating too much refrigerant through the restrictor I1. If the temperature externally of the refrigerator increases'abnormally the temperature and consequently the connected to one end of said device, a fixed repressure of refrigerant in the condenser Asimultaneously increases and both these temperatures cause a reduction in the size or cross-sectional area of the capillary passage in device 3l. The additional restricted ow or the increase of ow, as the case may be, of liquid refrigerant to the Vrestrictor I1 and into evaporator I8 counterbalances or compensates for the increase or decrease of refrigerant pressure within the system to thereby eliminate the difficulties hereinbefore enumerated and provide efficient operation of the refrigerating system irrespective of ambient temperatures.
It will be seen that my improvement of providing a compensating device in which a fixed continuously open refrigerant flow passage therethrough has its cross-sectional area changed or varied, by metal members having different coeiiicient of expansion and contraction relative to one another, I eliminate the use of 4movable valves or the like and the use of other materials in such an arrangement which might becomeinoperative through deterioration by the refrigerant within the system.` My improved compensating device is simple in construction and can be added or interposed in a refrigerating system without materially increasing the .cost thereof.
While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow:
What is claimed is as follows:
1. A refrigerating apparatus comprising, a temperature responsive refrigerant. ow compensatstrictor connected to the otherend of said device and an evaporator between said xed restrictor and said unit, said compensating device including a metal tube ,member and a metal rod member secured therein, said rod member normally being slightly smaller in diameter than the inside diameter of said tube member'to form a capillary passageway throughout the length of said device, the exterior of said device being -in contact with air in the vicinity of saidv condenser and the interior of said device being `in contact with high side refrigerant leaving said condenser, and one of said members of said device having a greater coefficient of expansion and contraction than the other thereof for varying the cross-sectional area of said passageway to control the amount of high side refrigerant admitted to said xed restrictor.
2. A refrigerating apparatus comprising, a temperature responsive refrigerant ow compensating device, a compressor unit having a condenser connected to one end of said device, a fixed restrictor connected to the other end of said device and an evaporator between said fixed restrictor and said unit, said compensating device including a metal tube member and a metalrod member secured therein, said rod member havingla groove therein forming a capillary passageway throughout the length of said device, the exterior of said device being in contact with airvin the vicinity of said condenser and the interior of said device being in contact with high side refrigerant leaving said condenser, and said rod member of said device having a greater coefficient of expansion and contraction than the tube member thereof for varying the cross-sectional area of said passageway to control the amount of high side refrigerant admitted to said fixed restrictor.
SYLVESTER M. SCHWELLER.
REFERENCES CITED The following references are of record in the le of this patent;-
UNrrnD STATES eA'rENrs Persons Nov. 21, 1944