US2813405A - Refrigerant condensing unit - Google Patents

Description

Nov.'19, 1957 T. M. ELFVING ET AL 2,813,405

I REFRIGERANT CONDENSING UNIT Fi led Sept. 29, 1955 2 Sheets- Sheet 1 ill j w w w /w Wm M w; o 5 w W..[ A mz/ mam T. M. ELFVING ETAL 2,813,405

REFRIGERANT CONDENSING UNIT Nov. 19, 1957 Filed Sept. 29, 1953 2 Sheets-Sheet 2 F'Lgore 3 United States Patent REFRIGERANT CONDENSING UNIT Thore M. Elfving and Claes T. Elfving, San Mateo, Calif.

Application September 29, 1953, Serial No. 383,071

3 Claims. (Cl. 62117.8)

The present invention relates to refrigeration com pressors and particularly to compressors of so-called hermetic or enclosed type, in which the compressor and its driving motor are contained in one enclosure and the refrigerant becomes the atmosphere in which the motor runs. The gaseous refrigerant returning from the evaporator in the suction pipe usually first enters the enclosure at the motor end. In traveling through the motor, it first removes heat from the motor winding and the motor metal and then passes to the compressor at the other end of the enclosure. The heat from motor and compressor absorbed by the refrigerant will eventually be removed with the other heat dissipated by the condenser.

The hermetic unit is not suitable for Wide variations in evaporator temperatures. Motors and compressors are designed to obtain proper cooling with a certain density of suction gas passing through the enclosure. A very considerable reduction in this density due to a large drop in evaporator temperature will greatly decrease the cooling effect that will be obtained. The result is inadequate cooling at evaporating temperatures materially below the design condition.

If the refrigerant gas in passing the motor winding becomes superheated, the power requirement per ton of refrigeration is increased.

It is an object of the invention to provide a refrigeration compressor in which adequate cooling of the motor-compressor unit is brought about regardless of the flow of refrigerant from the evaporator to the compressor.

Other objects and advantages will be apparent from a study of the following specifications taken in connection with the accompanying drawings wherein the invention is illustrated as adapted to a hermetic compressor unit.

Although the invention is especially related to compressors of the hermetic type the principles of the invention can also be applied to compressors of the open type.

In the drawings Figure 1 is a partly sectional end view of a hermetic compressor unit having a condenser and built-in receiver.

Figure 2 is a partly sectional front view of the same unit.

Figure 3 is a top view of another type of hermetic compressor unit having a condenser.

Figure 4 is a partly sectional view of the unit shown in Figure 3.

In Figure 1 and Figure 2 there is shown a hermetic motor-compressor unit having an enclosure with a compressor housing at one end and a motor housing 11 at the other end. The compressor 12 is of the piston type and has splash or forced lubrication and a resulting heat transfer between the piston and cylinder zone and the lower portion of the crankcase. It also has a discharge valve 13 from which a pipe 14 takes the refrigerant to a condenser 15, air cooled by means of a fan 16. From the condenser 15 a relatively large pipe 17 leads the liquid refrigerant downwardly to a receiver 18. According to the invention, the receiver to a large extent 2,813,405 Patented Nov. 19, 1957 surrounds the lower part of the motor-compressor unit so that the motor housing 11 and the lower part of the compressor housing 10 with the crankcase sump are in effect submerged in liquid refrigerant and consequently are in good heat transferring relationship therewith. From near the bottom of the receiver a pipe 19 carries liquid refrigerant through a heat exchanger 20 and from there to an expansion valve (not shown) and evaporator (not shown) in the usual Way. The return from the evaporator goes to the outer jacket of the heat exchanger from which a suction pipe 21 carries refrigerant gas back to the hermetic unit through an intake valve 22.

By the arrangement according to the invention, the motor-compressor enclosure will be efliciently cooled by refrigerant in the surrounding receiver 18. Heat given off through the motor-compressor housing to the liquid refrigerant in the receiver evaporates a corresponding amount of refrigerant. The formed vapor rises and enters the condenser 15 through the large pipe 17 and condenses. The pipe 17 is large enough so that there: can readily be a simultaneous flow of refrigerant gas passing from the receiver to the condenser in counterflow to the liquid refrigerant going from the condenser to the receiver. The pipe 17 and the condenser pipes 15 should therefore be pitched downwardly and be of liberal diameter so that gas will be allowed to rise from the receiver back into the condenser.

In case a small pipe condenser is used, or if the condenser or the pipe 17 is formed or installed to make liquid pockets, a separate recirculating cooling system may, according to the invention, be used. This separate recirculating cooling system comprises a heat dissipating part 23 in the form of a condenser coil located above the liquid surface in the receiver 18 and connected by a pipe 24 with the upper part of the receiver 31$, which forms the heat'absorbing part of the system. The pipe 24 and the condenser 23 preferably have an inner diameter of at least /2 with the connections made in such a way that all parts of the system are Well drained to the receiver. The cooling of the motor-compressor housing will take place by the evaporation of refrigerant in the receiver 18, the vapor rising into the coil 23 The vapor then condenses in the condenser coil 23 and as liquid will flow back to the receiver.

The receiver and thereby also the m'otor'compressor housing will, according to the invention, maintain a temperature only slightly higher than that of the coil 23. The auxiliary coil 23 should be located in front of the main or proper condenser 15 and is also provided with fins 25. The cooling coil 23 will be cooled to a temperature of the condenser 15 and the hermetic motor-compressor unit will therefore be efiiciently cooled during any working condition independent of the density of the suction gas. In order to maintain good heat transfer conditions the condenser coil 23 should be provided With a valve 26 for elimination of air or other non-condensable gases.

Figures 3 and 4 show another embodiment of the invention. A hermetic compressor 30 has a motor housing 31 located eccentrically above a compressor housing 32. A motor 33 drives a vertical shaft 34 provided with a hollow center 35, through which oil is pumped by an oil pump 36 at the lower end of the shaft below the oil level in the compressor housing. A compressor 37 with two horizontal cylinders 38 and 39 is driven by the vertioal shaft. At the top of the cylinders a valve chamber 40 is disposed and to which a suction line 41 and a discharge pipe 42 are connected. The discharge pipe 42 is connected with a condenser 43, air cooled by a fan 44. From the condenser 43 the liquid refrigerant is carried by a pipe as to a receiver at, which is built around the lower part of the compressor housing 32, so that the oil sump is in good heat transfer relationship with and in effect is submerged in liquid refrigerant. From the bottom of the receiver 46 a pipe 47 carries liquid refrigerant to an evaporator (not shown) preferably through a heat exchanger in the usual Way.

The receiver and the oil sump and the whole rnotorcompressor unit are cooled by a recirculation system using the refrigerant of the system as heat transfer medium. A heat dissipating part 48 or auxiliary condenser is located above the refrigerant liquid level in the receiver 46 and is connected therewith by a large, inclined pipe 49. The heat dissipating part, according to the invention, preferably includes a comparatively large condenser tube or coil provided with fins St for effective cooling by the air blown by the condenser fan 4 An air valve 51 is provided at the highest point of the coil for release of air in purging.

Heat from the oil sump is absorbed upon evaporation of a corresponding amount of refrigerant in the receiver 46. The refrigerant gases may partly reenter the lower portion of the condenser 43 but mainly pass through the pipe 49 to the heat dissipating part 48 of the cooling system. Therein condensation takes place at a temperature determined mainly by the temperature of the air and the heat transfer capacity of the heat dissipating part 48 in relation to the heat developed in the motor-compressor housing. The motor-compressor unit will in this Way be efficiently cooled Without outside air cooling, which in many places is difficult to arrange. By the invention it is no longer necessary to expose the hermetic compressor unit to outside forced air cooling and the condenser and the condenser fan do not have to be located in front of the compressor for passage of air over the motor-compressor housing.

In the described embodiments of the invention, the heat absorbing part of the cooling system serves as receiver for the condensing unit. it is, according to the invention, possible to arrange a separate heat absorbing part in heat transferring connection with the motorcompresso-r housing and with liquid communication with the condensereceiver system for the passage of liquid refrigerant to the heat absorbing part of the cooling sys tem without having the heat absorbing part serving as receiver. The heat absorbing part of the refrigerant recirculation system, according to the invention, may also consist of liquid pipes or coils located below the oil level inside the sump of the compressor or located in thermal contact with any part of the motor-compressor system, where cooling is desirable.

While several more or less specific embodiments of the invention have been shown, it is to be understood that this is for the purpose of illustration only, and that the invention is not to be limited thereby, but its scope is to be determined by the appended claims.

What is claimed and is to be secured by Letters Patent 1s:

1. A refrigeration compressor comprising a driving motor, a compressor connected thereto, a housing for said driving motor and said compressor having a heat transferring wall, a jacket enclosing at least part of said wall and forming a receiver for gaseous and liquid refrigerant, a condenser disposed above said receiver, means for carrying gaseous refrigerant from said compressor to said condenser, and a relatively large connecting pipe extending between the bottom of said condenser and said receiver above the liquid refrigerant therein, said pipe being of a size to conduct gaseous and liquid refrigerant simultaneously in opposite directions.

2. A refrigeration compressor comprising a driving motor, a compressor connected thereto, a housing for said driving motor and said compressor having a heat transferring wall, means including said wall forming a receiver for gaseous and liquid refrigerant, a condenser located in the atmosphere and disposed entirely above said liquid refrigerant in said receiver, means for circulating refrigerant from said receiver through said compressor and into said condenser, and a single pipe for freely conducting gaseous and liquid refrigerant simultaneously in both directions between said condenser and said receiver.

3. A refrigeration compressor comprising a driving motor, a compressor connected thereto, a housing for said driving motor and said compressor having a heat transferring wall, means including said wall forming a receiver for gaseous and liquid refrigerant, a condenser located in the atmosphere and disposed entirely above said liquid refrigerant in said receiver, means for circulating refrigerant from said receiver through said compressor and said condenser, means for draining liquid refrigerant from said condenser to said receiver, and means for conducting ascending gaseous refrigerant from said receiver directly to the bottom of said condenser, and in which said draining means and said conducting means include a pipe of a size to conduct gaseous and liquid refrigerant simultaneously in opposite directions and inclined downwardly from the bottom of said condenser to said receiver above the liquid refrigerant therein.

References Cited in the file of this patent UNITED STATES PATENTS 1,284,964 Anderson Nov. 19, 1918 1,313,363 Williams Aug. 19, 1919 1,509,998 Geiger et a1 Sept. 30, 1924 2,051,110 Smith Aug. 18, 1936 2,146,484 Philipp Feb. 7, 1939 2,300,005 Philipp Oct. 27, 1942 2,417,582 Barfield Mar. 18, 1947 2,478,137 Timmer Aug. 2, 1949 2,496,143 Backstrom J an. 31, 1950 2,672,736 Philipp Mar. 23, 1954

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