US2145354A

US2145354A - Refrigerating apparatus

Info

Publication number: US2145354A
Application number: US512632A
Authority: US
Inventors: Harry B Hull
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1931-01-31
Filing date: 1931-01-31
Publication date: 1939-01-31
Anticipated expiration: 1956-01-31

Description

Jan. 31, 1939. H. B. HULL 2,145,354

REFRIGERATING APPARATU S Filed Jan. 51, 1931 5 Sheets-Sheet 1 INVENTOR 7 BFW W ATTORNEY Jam. 31, 1939 H. B. HULL 2,145,354

REFRIGERATING APPARATUS Filed Jan. 31, 1931 3 Sheets-Sheet 2 W we INVENTOR M W BY ATTORNEY Jan. 31, 1939. H. B. HULL I 2,145,354,

REFRIGERATING APPARATUS Filed Jan. 51, 1931 3 Sheets-Sheet 3 HHH INVENTO i? Wm M W ATTORNEY M 3% Patented Jan. 31, 1939 UNITED STATES PATENT OFFICEJI REFRJGERATING APPARATUS Harry B. Hull, Dayton, Ohio, assignor, by mesne assignments, to

General Motors Corporation,

This invention relates to refrigerating apparatus and more particularly to the compression type of such apparatus.

In refrigerating systems of the compression type it is customary to connect the high pressure or discharge side of the compressor to a condenser and to connect the low pressure or inlet side of the compressor to an evaporator, the discharge side of the condenser being in turn connected to the inlet side of the evaporator. Systems of this type are provided with a body of lubricant, such as lubricating oil, for lubricating moving elements of the compressor. This body of lubricant is stored usually in the compressor crankcase which provides a reservoir therefor and which is in communication with the inlet of the compressor. In systems of this type where a lubricant, which is miscible with refrigerant in the system, is used for lubricating the compressor it has been found that where refrigerant from the low pressure side of the system is permitted to return to the oil reservoir during off cycles of the system in any appreciable amount, a com siderable amount of refrigerant is absorbed in the body of oil. Additional refrigerant enters the reservoir, some of which is further absorbed in the oil and some of which tends to build up pressures in the crankcase. It has also been found that when the pressure of the lubricant thuscharged with refrigerant, is quickly reduced by operation of the compressor, considerable frothing or foaming takes place in the oil reservoir which causes some of the foaming oil to be pumped to other parts of the system to thus affect the efficiency of the system. In so doing a portion of the lubricant is withdrawn from where it is required for lubrication of the compressor parts.

One of the objects of this invention is to provide means for gradually reducing the pressure built up in the crankcase when the compressor starts its running operation to thus prevent frothing or foaming of lubricant in the crankcase.

Another object is to provide improved means,

for preventing, to any appreciable extent, the absorption of refrigerant in the body of lubricant. Further objects and advantagesof the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings. Fig. 1 is a diagrammatic illustration of a refrigerating system embodying features of my invention, and showing an enlarged view of the compressor partly in cross section and partly in elevation; v I

Fig. 2 is a view similar to Fig. 1 showing a modified form of means for preventing the pressure in the crankcase from being quickly reduced upon operation of the compressor; and

Fig. 3 is a view showing other means for preventing the absorption of refrigerant in the body of oil in the compressor crankcase.

Referring to the drawings the numeral 20 des- 10 ignates in general a refrigerating system embodying features of my invention. The system 20 includes the compressor 22, condenser 23, receiver 24 and evaporator 25. A motor (not shown) is provided for driving the compressor 22 in the 15' I usual manner.

Refrigerant flows through the parts in the order named. That is, refrigerant is compressed in the compressor, discharged through conduit 30 into the condenser wherein it is liquefied and from which it passes to the re- 20 ceiver 24. Receiver 24 is connected to the evaporator by means of theliquid supply conduit 32. The liquid refrigerant in evaporator 25 vaporizes to produce a cooling effect and the vapors pass from the evaporator through a vapor conduit 34 25 to the compressor in a manner described hereinafter. In order to provide means for starting and stopping the motor in response to a predetermined high and low pressure conditions within the evaporator I have provided an automatic 30 switch 35. The switch 35 is operated by bellows 36 which is responsive to pressure within the vapor conduit 34. The motor and compressor are controlled in response to predetermined high and low pressure conditions within the evaporator. 35 In view of the fact that predetermined high and low pressures vary according to the temperature conditions Within the evaporator the motor compressor unit is in reality responsive to temperature conditions in the evaporator. The evapora 40 tor may be of any desired type, and for instance, may be of the flooded float controlled type similar to that described in the patent to R. G. Osborn, 1,556,708 patented Oct. 13, 1925.

Referring more in detail to the drawings the compressor includes a casing 40 which provides a crankcase portion 62 forming a reservoir for lubricating oil. The upper portion of the casing ll] provides a cylinder portion 45 in which reciprocates a piston 38 actuated by pitman 69 which 5 in turn is actuated by eccentric 50 carried by a drive shaft 52. The compressor also includes a discharge head which is provided with a discharge port 617 to which the conduit 30 is connected. The casing 40 is provided with an inlet 5 18 for gaseous refrigerant which is in communication with the vapor conduit 34 and leads to the crankcase portion 42. The casing 48 is also provided with an inlet H which communicates with the vapor conduit 34 and leads to the cylinder portion 45 of the casing 48. Admission of refrigerant to the inlet 18 is controlled by a throttling means 88 about to be described. 7

The throttling means 88 includes a valve proper 82 adapted to open and close passage 84 in response to pressure within the vapor conduit 34. The valve 82 is enclosed in a casing which carries an expansible bellows 81 which is adapted to actuate the valve 82. A chamber 83 formed by the casing 85 communicates with the vapor conduit .34 and leads to the compressor inlet H, and leads to the compressor inlet 18 through passageway 84 which is controlled by valve 82. As shown in Fig. 1 the piston 48 is provided with the slotted portion 98 having a passage 92 which leads to the central hollow portion 48a-of the piston 48. During the off cycle of the compressor 22 the gaseous refrigerant in conduit 34 builds up. a pressure in said conduit and in the chamber 83 which in turn expands the bellows 81 against the action of a spring 88 to actuate valve 82 to close passage 84. At this time the only gaseous refrigerant which is admitted to the crankcase of the compressor passes through vent I88 provided in the valve proper 82. Thus it will be apparent that the bellows 81 will maintain valve 82 closed until bellows 36 actuates switch 35 to cause the compressor to reduce the pressure in chamber 83 and conduit 34. Thus when the compressor starts operation gaseous refrigerant will be withdrawn from the chamber v83 into the hollow portion of the piston 48 through the compressor inlet 1I whence it will .be discharged through discharge valve II8 carried in the top of piston 48 and later discharged by the compressor into conduit 38 which leads to the condenser 23. When this takes place some gaseous refrigerant will be withdrawn from the compressor crankcase through compressor inlet 18 and vent I88. Thus it will be noted that when the compressor starts only a small amount of gaseous refrigerant will be withdrawn from the compressor crankcase or in other Words the pressure in said crankcase will be reduced gradually. -As the pressure within the conduit 34 and the chamber 83 is gradually reduced the bellows 81 permits the valve 82 to gradually open, at which time the pressure in the crankcase has been materially reduced and the remaining gaseous refrigerant therein can be withdrawn in accordance with the passage provided by valve 82 which is graduallybeing opened under the influence of the spring 88. By this arrangement it will be noted that in the .event any oil should be circulated throughout the system. it will be returned to the compressor crankcase through vapor conduit 34, passage 84 and compressor inlet 18.

Referring now to Fig. 2, there is shown a refrigerating system I28 comprising compressor I22, condenser I23 and evaporator I24. The operation of this system is similar to the operation of system 28. However, gaseous refrigerant is conducted from evaporator I24 through a vapor conduit I34 which leads to the compressor crankcase providing a reservoir for a body of lubricating oil. In this modification the compressor piston I48 is provided with a slotted portion I58 having a passage I52 which leads to a hollow portion I48a of piston I48. The gas from the hollow portion I48a is discharged through the valve I68. The slotted portion I52 communicates with the compressor crankcase through a passage I65. The passage I65 is controlled by a throttling means I18. The throttling means includes a valve I12 actuated by an expansible bellows I15 and adjustable spring I16. The bellows I15 acts against the spring I16 to close valve I12 when the pressure in the crankcase and in the bellows increases and the bellows acts under the influence of spring I16 to open valve I12 as the pressure in the crankcase and bellows decreases. During the oif cycle of the compressor the valve tends to close passage I65 from the crankcase. Thus, when the compressor starts, the'gas in the bellows I15 will be first withdrawn from the bellows to gradually open valve I12. This permits the gas in compressor crankcase to be gradually reduced to thereby gradually reduce the pressure therein. This arrangement prevents frothing or foaming of oil in the compressor crankcase.

In Fig. 3 there is shown another refrigerating system. This system is adapted to be intermittently operated by a motor 288 which drives compressor 282. The motor 288 is controlled by an automatic switch 285 which is responsive to predetermined pressures within the system. When there is a demand for refrigeration by the system the switch 285 places the motor in circuit with the power mains to thus drive the compressor. When the compressor is inoperative, the switch 285 connects an electric heating member 2I8 in circuit with the power mains. The heating member may be any suitable device for heating the lubricant in the system. As shown in Fig. 3 the heating member 2I8 is disposed below the level of oil in the compressor crankcase. The purpose of this heating member 2I8 is to heat the oil in the compressor crankcase during the off cycles of the compressor to thus prevent the refrigerant in the compressor crankcase from being absorbed in the body of oil. This prevents frothing and foaming of oil when the compressor starts operation.

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 closed refrigerating system comprising in combination a compressor, condenser and evaporator, said compressor being provided with a high pressure side communicating with said condenser and a low pressure side communicating with said evaporator, said compressor providing a reservoir for lubricant on the low pressure side of said compressor communicating with said evaporator, a quantity of lubricant in said reservoir miscible with said refrigerant, said compressing means including means for withdrawing gaseous refrigerant from said reservoir, com.-

pressing said refrigerant and delivering it to the high pressure side of said compressor, and automatic means for limiting the withdrawal of refrigerant from said reservoir.

2. A closed refrgerating system comprising in combination a compressor, condenser and evaporator, said compressor being provided with a high pressure side communicating with said con-' denser and a low pressure side communicatn with said evaporator, said compressor providing a reservoir for lubricant on the low pressure side of said compressor communicating with said evaporator, a quantity of lubricant in said reservoir miscible with said refrigerant, said com pressing means including means for withdrawing gaseous refrigerant fromsaid reservoir, conipressing said refrigerant and delivering it to the high pressure side of said compressor, and a valve responsive to pressures on the low pressure side of said compressor for limiting the withdrawal of refrigerant from said reservoir.

3. A closed refrigerating system comprising in combination a compressor, condenser and evaporator, said compressor being provided with a high pressure side and a low pressure side, a conduit connecting said condenser to the high pressure side of said compressor, a vapor conduit connecting said evaporator with the low pressure side of said compressor, said compres sor providing a reservoir for lubricant, a quantity of lubricant in said reservoir miscible with said refrigerant, means providing a passage leading from said vapor conduit to said reservoir, said compressor including means for withdrawing gaseous refrigerant from said vapor conduit and from said reservoir through said passage, and automatic means for restricting said passage.

4. A closed refrigerating system comprising in combination a compressor, condenser and evaporator, said compressor being provided with a high pressure side and a low pressure side, a conduit connecting said condenser to the high pressure side of said compressor, a vapor conduit connecting said evaporator with the low pressure side of said compressor, said compressor providing a reservoir for lubricant, a ,quantity of lubricant in said reservoir miscible with said refrigerant, means providing a passage leading from said vapor conduit to said reservoir, said compressor including means for withdrawing gaseous refrigerant from said vapor conduit and from said reservoir through said passage, and a valve responsive to pressures in said vapor conduit for restricting said passage.

5. A closed refrigerating system comprising in combination a compressor, condenser and evaporator, said compressor being provided with a high pressure side and a low pressure side, a conduit connecting said condenser to the high pressure side of said compressor, said compressor, providing a reservoir for lubricant, a quantity of lubricant in said reservoir miscible with said refrigerant, a vapor conduit connecting said evaporator with said reservoir, said compressor including means for withdrawing gaseous refrigerant from said reservoir, compressing said refrigerant and delivering it to the high pressure side of said compressor, and automatic means for limiting the withdrawal of refrigerant from said reservoir.

6. A closed refrigerating system comprising in combination a compressor, condenser and evaporator, said compressor being provided with a high pressure side and a low pressure side, a conduit connecting said condenser to the high pressure side of said compressor, said compressor providing a reservoir for lubricant, a quantity of lubricant in said reservoir miscible with said refrigerant, a vapor conduit connecting said evaporator with said reservoir, said compressor including means for withdrawing gaseous refrigerant from said reservoir, compressing said refrigerant and delivering it to the high pressure side of said compressor, and a valve responsive to pressures on the low pressure side of said compressor for limiting the withdrawal of refrigerant from said reservoir.

7. A closed refrigerating system comprising in combination, a compressor, a condenser and an evaporator, said compressor being provided with a high pressure side communicating with said condenser and a low pressure side communicating with said evaporator, said compressor providing a reservoir for lubricant on said low pressure side of said system, a quantity of lubricant in said reservoir miscible with refrigerant in the system, means within the compressor for withdrawing gaseous refrigerant from said reservoir and said evaporator and for compressing same and delivering said compressed refrigerant to the high pressure side of the system, and pressure responsive means interposed in the path of flow of gaseous refrigerant from said evaporator to said first named means for restricting the flow of gaseous refrigerant from said reservoir to said first named means during one part only of the operation of said first named means.

8. Refrigerating apparatus comprising a closed refrigerant circuit including a. compressor having a compressing chamber and a lubricant reservoir substantially separated from the closed circuit, a condenser and a cooling unit, a chamber in said closed circuit for collecting lubricant from the refrigerant, a conduit connecting said chamber and the lubricant reservoir, and a valve in said conduit tending to restrict flow through said conduit during periods when-the lubricant in said reservoir tends to foam.

9. Refrigerating apparatus comprising a closed refrigerant circuit including a compressor having a compressing chamber and a lubricant reservoir substantially separated from the closed circuit, a condenser and a cooling unit, a chamber in said closed circuit for collecting lubricant from the refrigerant, .a conduit connecting said chamber and the lubricant reservoir, and a valve in said conduit tending to restrict flow through said conduit during periods when the lubricant in said reservoir tends to foam and a bleeder vent in said valve.

10. Refrigerating apparatus comprising a closed refrigerant circuit including a compressor having a compressing chamber and a lubricant reservoir substantially separated from the closed circuit, a condenser and a cooling unit, a chamber in said closed circuit for collecting lubricant from the refrigerant, a conduit connecting said chamber and the lubricant reservoir, and means in said conduit tending to restrict the fiow of refrigerant through said conduit during the starting periods of said compressor.

11. Refrigerating apparatus comprising a closed refrigerant circuit including a compressor having a compressing chamber and a lubricant reservoir substantially separated from the closed circuit, a condenser and a cooling unit, a chamber in said closed circuit for'collecting lubricant from the refrigerant, and means providing a restrictive orifice connecting said chamber and the lubricant reservoir and tending to restrict the flow of refrigerant from said reservoir to said chamber during the starting period of said com- DIGSSOI.

HARRY B. HULL.