US2168367A - Refrigerating apparatus - Google Patents

Description

Aug. 8, 1939. A. A. KUCHER REFRIGEBATING APPARATUS Original Filed Oct.= I9, 1934 UINVENTOR. A/v'mnv A. five/sum ATTORNEY.

Patented Aug. 8, 1939 UNITED STATES REFRIGERATIKTG APPARATUS Andrew A. Kucher, Dayton, Ohio, asaignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware 7 Application October 19, 1934, Serial No. 749,015

Renewed October 23, 1937 6 Claims.

tus and more particularly to a novel system and control therefor for automatically varying the refrigeration output of the apparatus. Heretofore in the construction of refrigerators, particularly those comprising a cabinet having a food storage compartment and which are intended principally for household use, in meeting the problem of varying the refrigeration output of the machine to provide substantially constant food preserving temperatures in the cabinet, it has been customary to provide an automatic switch for stopping and starting the refrigerant liquefying unit as by controlling the motor which drives the compressor and to thus operate the apparatus intermittently. With such a method of control, the system, while it is operating, produces refrigeration'at a substantially constant rate and the variation in average amount of refrigeration produced over a given period results from variations in the length of the periods during which the machine operates or is idle. A system of this type necessitates the use of some form of automatic switch, usually thermostatic or controlled in response to the low side pressure in the refrigerating machine. It v is well known that the switch is a somewhat costly piece of apparatus and itis, furthermore, a principal source of trouble in service. For example, the service records for one particular type of household refrigerator which has been produced in large quantities show that over 60% of the service calls are due to switch trouble.

It is an object, therefore, of the present invention to provide a refrigerating apparatus which is readily adapted to extremely low cost production and in which service difficulties arising from the provision of an automatic switch are eliminated.

More specifically, it is an object of the invention to provide a refrigerating apparatus comprising a refrigerant liquefying unit and an evaporator for maintaining a desired low temperature within a food compartment or other compartment to be cooled and in which the refrigeration 0 output of the apparatus may be varied, while maintaining the refrigerant liquefying' unit in operation.

Further objects and advantages of the present invention will be apparent from the following description, reference being bad to the accompanying drawing, wherein a preferred form of the invention is clearly shown.

In the drawing:

The figure is a diagrammatic view of a refrigerating systemembodying the present invention, and in which the evaporator construction is shown in cross section and on a larger scale.

According to the present invention, the apparatus may comprise generally a refrigerant liquefying unit including a compressor I3 and a condevice such as a split phase motor 32.

This invention relates to refrigerating apparadenser l2 connected thereto by conduit ll, a refrigerant expansion control device such as a high side float valve I6 communicating with the outlet of the condenser l2 by a conduit l8 and an evaporator having an inlet 22 connected to the float valve by a conduit 24. The compressor Ill may be of any well known type and is illustrated diagrammatically as of the rotary type having an inlet 26 communicating with an outlet 23 of the evaporator by conduit 30. The compressor "I may be driven by a suitable motive The motor and compressor are preferably mounted in a hermetically sealed casing indicated by the dotted rectangle 34. The evaporator 20 is mounted within the food compartment of a household refrigerator or within anyother desired compartment to be cooled as indicated by the dotted line 36.

'The evaporator of the present invention is formed of 'two distinct portions 33 and 40 which may be formed as generally flat vertical hollow plates. The portion 33 is also formed with integral horizontal hollow shelves 42 for supporting water-containing ice trays or other objects to be frozen. Each of the portions 38 and 40 is provided with an enlarged portion H and 46 at the top thereof forming a chamber from which the evaporated refrigerant'is withdrawn through suitable outlet conduits l3 and 50. The conduit 50 is in communication with the conduit 48 and with the outlet connection 28. At the bottom of the evaporator the two portions 33 and 40 are connected by a transverse liquid conduit 52 through which liquid refrigerant may pass in either direction from one portion to the other. A cover plate 54 is preferably attached to the top of the portions 33 and 40 to shield the compartment between them from the circulating air within the compartment 36.

The proportions of the various parts of the refrigerating apparatus are preferably so corre lated with each other and with respect to the -maximum loads to be handled that each part is just capable of satisfactory performance under maximum load. For example, if the apparatus is used with an ordinary household refrigerator cabinet, the maximum heat leakage through the cabinet walls at the highest room temperature for which the device is intended to operate satisfac-.

torily together with the additional heat loads arising from food belng'placed in the cabinet and the apparatus is preferably designed to have the same in both portions of the evaporator.

lowest capacity possible to produce the amount a thermostatic valve 56 for controlling the outlet connection 50. The valve 56 may comprise a bellows 58, which is charged with a volatile fluid. The upper end of the bellows G is rigidly secured to a depending portion of the outlet conduit 50, while the bottom end of the bellows 58 carries a yoke member 62 which extends upwardly around the bellows 58 and extends through openings 64 in the depending portion 50 to carry the valve 56. It will be understood that other forms of automatic control may be used. For example, the bellows may be operated from a remote bulb as is well known in the art.

In order to provide for initial starting of the motor 32 when the apparatus is first connected to a suitable source of electric current, or when the supply of current is resumed after an interrupt'ion, a suitable automatic switch 66 is provided for controlling the circuit of the split phase motor to insure its starting.

In operation, the motor 32, being connected to a suitablesupply line through switch 65, is immediately started and continues to drive the compressor l0 at a substantially constant rate. Gaseous refrigerant is withdrawn from the evaporator through the conduit 30 by the compressor l0 and compressed and delivered through conduit l4 to the condenser l2. The room air or other suitable cooling medium to which the condenser i2 is exposed liquefies the compressed refrigerant therein for delivery through the conduit l8 to the float valve IS. The valve l6 delivers liquid refrigerant as fast as it is produced to the inlet connection 22 of the evaporator through the liquid line 24. If the air in the food compartment is above the normal food preservation temperature at the time of starting, the

volatile fluid in the bellows 58 will be underhigh pressure, due to the volatilization thereof and the resulting expansion of the bellows 58 will maintain the valve 56 open. Under these conditions, it will be seen that the two portions 38 and 40 of the evaporator are in open communication through the conduit 52 at the bottom and conduits 48 and 50 at the top. Under these conditions, the liquid level in the evaporator will be substantially as illustrated and will beBtrtile 0 portions of the evaporator will, therefore, absorb heat from the circulating air to evaporate the refrigerant in the evaporator at a rate substantially equal to the maximum rate at which the compressor can withdraw refrigerant through the conduit 30. As soon as suflicient heat has been withdrawn from the circulating air in compartment 36 to bring its temperature down to the desired food preserving temperature,,the rate of vaporization of refrigerant in the evaporator will be consequently reduced, permitting the compressor to reduce the suction pressure in the portions 38 and 40. The temperature of the gaseous refrigerant within the enlarged portion 46 is' therefore reduced and the bellows 58 is permitted to retract tending to close the valve 55. As soon as the valve 56 closes sufiiciently to prevent gaseous refrigerant from beingwithdrawn through the conduit 50 at as great a rate as it is being evaporated in the portion 40, the pressure within the portion 40 tends to rise above that in the portion 38. consequently forcing liquid portion 38. This reduces the amount of liquid v refrigerant in the portion 40, or to put it in other words, decreases the area of the evaporator which is effective for heat exchange between the circulating air and the evaporating refrigerant. The refrigerating output of the apparatus as a whole is, therefore, reduced tocorrespond to the reduced refrigerating requirements within the compartment 36, while the operation of the liquefying unit including the compressor I0 is continued.

Since the evaporator under these conditions is in effect reduced in size, it will be seen that it is therefore out of proportion to the remainder of the system and although the effective size or capacity of the liquefying unit is not altered, the reduction in refrigeration output is obtained 'through operation of the system at reduced efficiency It will, therefore, be seen thatthe rate of withdrawal of heat by the evaporator as a whole is varied automatically to correspond to the requirements ,for heat withdrawal within the compartment 35.

It will be noted that the shelves 42 are in communication with the portion 38 of the evaporator which is always in operation regardless of the position of the valve 56. The freezing of ice within the ice trays on the shelves 42 is, therefore, possible at any time and is not dependent on the refrigerating load requirements of the cabinet itself, since the portion 38 is in the refrig'erant circuit at all times regardless of the conditions of the valve 56.

Thus, it will be seen that the present invention provides a refrigerating apparatus which can be constructed at a low initial cost-and which provides for automatic variation of the rate of .heat absorption at the evaporator by varying the path of refrigerant through the evaporator or in other words by controlling the amount of evaporator surface which is eifective for withdrawal of heat.

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, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A refrigerating apparatus comprising in combination, a refrigerant compressor, a motor for operating said compressor, a condenser, an-

, tween, one of the said two evaporator portions forming one wall of a freezing chamber within said compartment and the other of said two evaporator portions forming another wall of said freezing chamber for shielding the chamber from air circulating in said compartment, means for conducting liquid refrigerant into and conducting gaseous refrigerant out of said portions of said evaporator, said means being in constantly open communication with one of said evaporator portions, and thermostatic means for controlling the flow of refrigerant through the other of said evaporator portions of said evaporator construction.

2. A refrigerating apparatus comprising in combination, a refrigerant compressor, a motor for operating said compressor, a condenser, an evaporator, said evaporator being of a unitary construction and mounted in a food storage compartment in spaced relation to the walls thereof for cooling and causing circulationof air therein,

said unitary evaporator construction including.

two refrigerant evaporating portions having a refrigerant conveying communication therebetween, one of the said two evaporator portions forming one wall of a freezing chamber within said compartment and the other of said two evaporator portions forming another wall of said freezing chamber for shielding the chamber from air circulating in said compartment, means for path of flow of refrigerant through said evaporator construction.

3. A refrigerating apparatus comprising in combination, a refrigerant compressor, a motor for operating said compressor, a condenser, an evaporator, said evaporatorbeing of a unitary construction and mounted in a food storage compartment inspaced relation to the walls thereof for cooling and causing circulation of air there' in, said unitary evaporator construction including two refrigerant evaporating portions having a refrigerant conveying communication therebetween, one of the said two evaporator portions forming one wall of a freezing chamber within said compartment and the other of said two evaporator portions forming another wall of said freezing chamber for shielding the chamber from air circulating in said compartment, one of said evaporator portions being constructed and arranged to provide a refrigerated sharp freezing support within said freezing chamber for receiv ing a receptacle adapted to contain a substance to be frozen, means for conducting liquid refrigerant into and conducting gaseous refrigerant out of said portions of said evaporator, said means being in constantly open communication with said one of said evaporator portions, and thermostatic means for controlling the flow of refrigerant through the other of said evaporator portions of said evaporator construction.

4. A refrigerating apparatus comprising in combination, a refrigerant compressor, a motor for operating said compressor, a condenser, an evaporator, said evaporator being of a unitary construction and mounted in a food storage compartment in spaced relation to the walls thereof for cooling and causing circulation of air therein, said unitary evaporator construction including two refrigerant evaporating portions having a refrigerant conveying communication therebetween, one of the said two evaporator portions forming one wall of a freezing chamber within said compartment and the other of said two evaporator portions forming another wall of said freezing chamberfor shielding the chamber from air circulating in said compartment, one of said evaporator portions being constructed and arranged to provide a refrigerated sharp freezing support within said freezing chamber for receiving a receptacle adapted to contain a substance to be frozen, means for conducting liquid refrigerant into and conducting gaseous refrigerant out of said portions of said evaporator, said means being in constantly open communication with said one of said evaporator portions, and means actuated in response to the temperature of refrigerant flowing through the other of said evaporator portions for varying the path of flow of refrigerant through said evaporator construction.

5. A refrigerating apparatus comprising in combination, a food storage compartment, a refri'gerating system for said compartment including a compressor, ,a condenser and a unitary evaporator construction in which the refrigerant flows in a closed cycle, said evaporator construction being mounted in said compartment in spaced relation to the walls thereof for cooling and causing circulation of air therein, said unitary evaporator constructionincluding two'refrigerant evaporating portions exposed to the same medium to be cooled and having a refrigerant communication ,therebetween, one of said two evaporator portions forming one wall of a freezing chamber within said compartment adapted to receive and support a receptacle containing a substance to be frozen and the other of said two evaporator portions forming another wall of said freezing chamber for shielding the chamber from air circulating in said compartment, said compressorbeing operated continu-. ously during the entire period of refrigeration demand of 'said compartment, means for conducting liquid refrigerant into and conducting gaseous refrigerant out of said portions of said evaporator construction, said means being in constantly open communication with one of said evaporator portions, and thermostatic means for controlling the flow of refrigerant through the other of said; evaporator portions of said evaporator construction.

6. A refrigerating apparatus comprising in combination, a food storage compartment, a refrigerating system for said compartment including a compressor, a condenser and a unitary evaporator construction in which the refrigerant flows in a closed cycle, said evaporator construction being mounted in said compartment in spaced relation to the walls thereof for cooling and causing circulation of air therein, said unitary evaporator construction including tworefrigerant evaporating portions exposed to the same medium to be cooled and having a refrigerant communication therebetween, one of said two evaporator portions forming one wall of a freezing chamber within said compartment adapted to receive and support a receptacle containing a substance to be frozen and the other of said two evaporator portions forming another wall of said freezing chamber for shielding the ANDREW A. KUCHER.

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