US3721108A - Refrigerant cooled compressor - Google Patents

Abstract

In a refrigerating system including a compressor, condenser, evaporator, and an oil cooler, a refrigerant cooling system for the compressor including a bypass line connected between the condenser and evaporator, and including a pump for providing high pressure liquid to the oil cooler and to the heads of the compressors, and a return conduit connecting the discharge refrigerant from the compressor cooling system through a desuperheater in the compressor discharge line to the condenser.

Description

United States Patent [1 1 [111 3,721,108 Kocher1March 20, 1973 [541 REFRIGERANT COOLED 3,270,521 9/1966 Rayner ..62/469 COMPRESSOR 3,379,033 4/1968 Grant Inventor: Erich J Kocher, Milwaukee, Wis. 3,548,612 12/1970 Mltubayashl ..62/505 [73] Assignee: Vilter Manufacturing Corporation, Primary Examiner-Meyer Perlin Milwaukee, Wis. Attorney-James E. Nilles 22 Fl (1: 15 1 1 1 June 97 57 ABSTRACT [21] Appl. No.: 153,230

In a refrigerating system including a compressor, condenser, evaporator, and an oil cooler, a refrigerant U-S. cooling ystem for the compressor including a bypass line connected between the condenser and evapofa- [58] Field of Search ..62/196, 84, 469, 470, 505, tor and including a pump f providing high pressure 62/510 2 liquid to the oil cooler and to the heads of the compressors, and a return conduit connecting the [56] References cued discharge refrigerant from the compressor cooling UNITED STATES PATENTS system through a desuperheater in the compressor discharge line to the condenser. 2,755,634 7/1956 Simmons .Q....62/51O 3,021,689 2/1962 Miller 5 Claims, 3 Drawing Figures REFRIGERANT COOLEI) COMPRESSOR BACKGROUND OF THE INVENTION It has been the practice for many years to cool ammonia and R-22 refrigerant compressors with water by circulating the water around the compressor heads. The water would initially pass through the oil cooler and then through the compressor jackets and be discharged to an open drain. As the cost of water increased, it became necessary to use the liquid refrigerant as a cooler as shown in Grant Pat. No. 3,379,033. In this type of a system, the oil cooler and the jackets are supplied with refrigerant through a thermostatic expansion valve. The evaporating temperature is controlled by a backpressure regulator which holds the evaporating temperature at a preset fixed level. The evaporated refrigerant is then fed back into the compression suction line. A liquid line solenoid valve is installed ahead of the expansion valve to prevent feeding refrigerant into the compressor when the compressor does not operate. The principal drawback to this type of a system is the reduction in the useful capacity of the compressor as a result of the reduction of the coolant refrigerant temperature in passing through the oil cooler and compressor jacket. As a result, the compressor must be down-rated in capacity. Also, in this type of a system three automatic valves are used in order to make the system operate.

SUMMARY OF THE INVENTION The refrigeration system of the present invention generally includes a compressor, condenser, high pressure receiver, and an evaporator. An oil separator is provided in the discharge conduit from the compressor to the condenser. Liquid refrigerant from the condenser is bypassed by a pump to the oil cooler, then to the compressor jackets, and back to the condenser. The liquid refrigerant is evaporated as it passes through the oil cooler and compressor jackets, with evaporation taking place at the condensing temperature. It should be apparent that this system does not affect compressor capacity since the refrigerant which is used to cool the compressors is returned to the condenser. Increased load, if any, is present in the condenser, rather than the compressor. It also should be apparent that the system eliminates the use of water. The only additional mechanical device required to operate this system is a small pump provided in the bypass line. Self-regulation is also provided by this system since evaporation takes place at the condensing temperature and therefore cannot overcool the oil cooler or compressor jackets.

The effectiveness of the oil separator can also be increased by the present system by incorporating a de-superheater in the compressor discharge line and in the refrigerant discharge line. Since evaporation of the liquid refrigerant in the compressor cooling jackets is achieved at condensing temperature, overcooling of the discharge gas from the compressor is prevented. The compressor discharge gas will therefore never be reduced below condensing temperature and will always be a gas as it passes through the oil separator. It is generally well known that an oil separator operates better at lower temperatures in separating oil from high pressure gas such as the refrigerant in the discharge conduit from the compressor.

Other objects and advantages of this invention will become apparent from the following description when read in connection with the accompanying drawings.

THE DRAWINGS FIG. 1 is a diagrammatic view of a refrigeration cycle incorporating the present invention;

FIG. 2 is a diagrammatic view of an alternate refrigeration cycle incorporating the present invention;

FIG. 3 is a perspective view of a compressor incorporating the concept of the present invention.

DESCRIPTION OF THE INVENTION A refrigeration system of the type contemplated herein generally includes acompressor 10 having a lowpressure suction conduit 12 and a high pressure discharge line orconduit 14. The highpressure discharge conduit 14 is connected to acondenser 16 through anoil separator 18. Thecondenser 16 is connected to anevaporator 19 by a high pressureliquid refrigerant conduit 20. Ahigh pressure receiver 22 and anexpansion valve 24 can be provided in theconduit 20. Theevaporator 19 is connected to thecompressor 10 by the lowpressure suction conduit 12. Anoil cooler 26 is connected to the crankcase of thecompressor 10.

In accordance with the invention, means are provided for bypassing liquid refrigerant fromconduit 20 to cool the compressor cylinder heads orjackets 30. Such means is in the form of abypass conduit 28 connected between the high pressureliquid refrigerant conduit 20 and theoil cooler 26. Any liquid refrigerant which passes through theoil cooler 26 is directed to thecompressor heads 30 of thecompressor 10, by means of aconduit 32 connected to a pair ofinlet conduits 34 connected to thecylinder heads 30 for the compressors. The gaseous discharge from thecylinder heads 30 is returned to thecondenser 16 through arefrigerant discharge conduit 36.

As seen in FIG. I, the high pressure liquid refrigerant bypassed from theconduit 20 by thebypass conduit 28 is pumped by means of apump 40 through theoil cooler 26 into thejackets 30 of thecompressor 10. Some of the liquid refrigerant is evaporated in theoil cooler 26 and the compressor jackets orheads 30. Evaporation of the liquid refrigerant which does occur in passing through the oil cooler and compressor jackets is normally achieved at condenser temperature. This is due to the absence of complete evaporation by the flow of the liquid refrigerant through the oil cooler and the compressor. The vaporized refrigerant which is evaporated in passing through the oil cooler and compressor jackets is recondensed when it returns to the cylinder.

More particularly, and referring to FIG. 3, acompressor 10 of the type contemplated herein generally includes a number ofcompressor cylinder heads 30. Theheads 30 are connected in series by theconduits 34 which pass through the heads on each side of the compressor and are connected to thecommon discharge conduit 36. Theoil cooler 26 is connected to the crankcase byoil lines 44 and 46. The rate of flow of liquid refrigerant through the compressor jackets orheads 30 normally required to achieve sufficient cooling can be predetermined from the rated capacity of the compressor. This effect is achieved without reducing the the compressor capacity since the entire flow of liquid refrigerant for cooling is independent of the flow of refrigerant through thecompressor 10. Thepump 40 can be selected initially on the basis of the rate of capacity of the compressor to provide sufficient liquid refrigerant flow to achieve the desired result.

Referring to FIG. 2 of the drawing, a modified system is shown which includes a compressor having inlet anddischarge passages 12 and 14, acondenser 16 and anoil separator 18. The condenser is connected to theevaporator 19 through ahigh pressure receiver 22 by aliquid refrigerant conduit 20. Anexpansion valve 24 is provided in theconduit 20, as is generally understood in the art. Liquid refrigerant is bypassed by means of thebypass conduit 28 and thepump 40 through theoil cooler 26 into thecompressor heads 30 throughconduits 32 and 34.

In this system, thedischarge conduit 36 is connected through a de-superheater 48 to thecondenser 16 bydischarge conduit 36. The highpressure discharge line 14 of the compressor is connected in heat exchange relationship with liquid refrigerant from the cooling system through the de-superheater 48 to thecondenser 16. This system provides an increase in the effectiveness or efficiency of theoil separator 18 by reducing the temperature of the discharge gas from the compressor inconduit 14. It is generally well known that anoil separator 18 works better at low superheated vapor than with the higher superheated vapors. Since evaporation of the liquid refrigerant from the cooling system in the de-superheater is always at condenser temperature, as described above, overcooling of the discharge gas from thecompressor 10 is prevented thereby reducing the discharge gas temperature without allowing liquid refrigerant to enter theoil separator 18.

Iclaim:

1. In a refrigerating system including a compressor having at least one compression cylinder, a condenser,

a first high pressure discharge conduit connecting said compressor to said condenser,

an oil separator connected to said discharge conduit between said compressor and said condenser,

an evaporator,

a second high pressure liquid refrigerant conduit connecting said condenser to said evaporator,

an expansion valve in said second conduit,

a third low pressure liquid refrigerant conduit connecting said evaporator to said compressor,

an oil cooler connected to said compressor,

a cylinder head for said compressor cylinder,

a fourth bypass conduit connecting said second liquid refrigerant conduit in heat exchange relation to said oil cooler,

a liquid refrigerant pump means in said fourth conduit for pumping liquid refrigerant to said oil cooler,

a fifth conduit connecting said oil cooler discharge refrigerant to said cylinder head, and

a sixth conduit connecting said cylinder head discharge refrigerant to said condenser.

2. In a refrigerating system according to claim 1 including a plurality of compressor heads, each being connected in serieswith said fifth conduit.

3. In a refrigerating system according to claim 1 including a de-superheater connected in said first conduit and said sixth conduit to place said high pressure refrigerant from said compressor in heat exchange relation with the compressor head refrigerant discharge gas.

4. A refrigerating system including a compressor having a number of cylinder heads,

a condenser and an evaporator,

means for connecting the condenser, evaporator and compressor in series,

an expansion valve in said connecting means between said condenser and said evaporator,

an oil cooler connected to the compressor,

means for bypassing high pressure liquid refrigerant in heat exchange relation through said oil cooler to said cylinder heads, said means including a bypass conduit connected to bypass the high pressure liquid refrigerant from said condenser to said cooler,

a refrigerant coolant discharge conduit connecting said cylinder heads to said condenser, and

a liquid refrigerant pump in said bypass conduit for pumping liquid refrigerant to said oil cooler.

5. The refrigerating system according to claim 4 wherein said connecting means includes a high pressure refrigerant discharge conduit connected between said compressor and said condenser, an oil separator connected in said high pressure refrigerant discharge conduit and a de-superheater connected in said high pressure refrigerant discharge conduit between said compressor and said oil separator, said refrigerant coolant discharge conduit being connected to said oil separator in heat exchange relation with said high pressure refrigerant.

Claims (5)

1. In a refrigerating system including a compressor having at least one compression cylinder, a condenser, a first high pressure discharge conduit connecting said compressor to said condenser, an oil separator connected to said discharge conduit between said compressor and said condenser, an evaporator, a second high pressure liquid refrigerant conduit connecting said condenser to said evaporator, an expansion valve in said second conduit, a third low pressure liquid refrigerant conduit connecting said evaporator to said compressor, an oil cooler connected to said compressor, a cylinder head for said compressor cylinder, a fourth bypass conduit connecting said second liquid refrigerant conduit in heat exchange relation to said oil cooler, a liquid refrigerant pump means in said fourth conduit for pumping liquid refrigerant to said oil cooler, a fifth conduit connecting said oil cooler discharge refrigerant to said cylinder head, and a sixth conduit connecting said cylinder head discharge refrigerant to said condenser.

2. In a refrigerating system according to claim 1 including a plurality of compressor heads, each being connected in series with said fifth conduit.

3. In a refrigerating system according to claim 1 including a de-superheater connected in said first conduit and said sixth conduit to place said high pressure refrigerant from said compressor in heat exchange relation with the compressor head refrigerant discharge gas.

4. A refrigerating system including a compressor having a number of cylinder heads, a condenser and an evaporator, means for connecting the condenser, evaporator and compressor in series, an expansion valve in said connecting means between said condenser and said evaporator, an oil cooler connected to the compressor, means for bypassing high pressure liquid refrigerant in heat exchange relation through said oil cooler to said cylinder heads, said means including a bypass conduit connected to bypass the high pressure liquid refrigerant from said condenser to said cooler, a refrigerant coolant discharge conduit connecting said cylinder heads to said condenser, and a liquid refrigerant pump in said bypass conduit for pumping liquid refrigerant to said oil cooler.

5. The refrigerating system according to claim 4 wherein said connecting means includes a high pressure refrigerant discharge conduit connected between said compressor and said condenser, an oil separator connected in said high pressure refrigerant discharge conduit and a de-superheater connected in said high pressure rEfrigerant discharge conduit between said compressor and said oil separator, said refrigerant coolant discharge conduit being connected to said oil separator in heat exchange relation with said high pressure refrigerant.

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