US2976699A - Refrigeration unit - Google Patents

Description

March 28, 1961 H. c. SMITH REFRIGERATION UNIT Filed July l5, 1959 2 Sheets-Sheet 1 March 28, 1961 H. c. SMITH 2,976,699

REFRIGERATION UNIT Filed July 13, 1959 2 Sl'xeets-SheeiI 2 REFRIGERATION UNIT Hugo C. Smith, Brecksville, Ohio, assgnor to Hugo C. Smith Corp., Cleveland, Ohio, a corporation of Ohio Filed July 13, 1959, Ser. No. 826,583

13 Claims. (Cl. 62-278) This invention relates to refrigeration apparatus and more particularly to refrigeration units of the so-called hermetically sealed type.

Refrigeration units consisting of a motor and a compressor in a sealed housing are well-known. The present invention relates to a refrigeration apparatus in which not only the motor and compressor are contained within a sealed housing, but also the condenser and accumulator are contained within the same housing.

The general object of the invention is to provide an improved refrigeration unit of compact form which can be constructed economically and which will be efficient and reliable in service. Other objects are the provision of a refrigeration unit embodying a hermetically sealed motor and compressor and in which the condenser and the receiver for liquefied refrigerant surround the housing for the motor and compressor and are joined integrally therewith; the provision of a refrigeration unit having an accumulator on the suction side of the compressor that is arranged to prevent any possibility of liquid refrigerant being returned to the compressor; the provision of a refrigeration unit having an accumulator that surrounds the motor and compressor; the provision of a refrigeration unit that is particularly adapted for use in systems embodying automatic or manually controlled defrosting cycles; and the provision of a refrigeration unit that can be adapted for water, air or evaporative cooling.

Further objects and advantages of the invention will become apparent from the following description of a preferred form thereof, reference being made to the accompanying drawings.

Referring to the drawings,

Figure 1- is a vertical sectional view through a refrigeration unit made according to a preferred form of my invention and embodying a water-cooled condenser. The figure illustrates diagrammatically the connection of the unit to an evaporator embodying a hot gas defrosting system.

Figure 2 is a view similar to Figure 1 but illustrating a unit embodying an air-cooled condenser.

Figure 3 is a vertical sectional view through a refrigeration unit embodying an evaporative-cooled condenser; the section being taken with the unit rotated 120 from the position of the units in Figures 1 and 2.

Figure 4 is a horizontal sectional view on a reduced scale taken along the line 4 4 of Figure 3.

Referring to Figure 1, a preferred form of refrigeration unit embodying my invention comprises a sealed compressor and motor unit which may be of generally conventional construction and is made up of a cylindrical housing 11 having top and bottom end members 12 and 13 welded or otherwise joined thereto. The end members carry appropriate bearings 15 and 16 which support the shaft 1S; a motor 19 is mounted on the shaft 18 and the shaft has an eccentric 20 that reciprocates piston 21 within cylinder 22 of a conventional compressor 23. The compressor has a suction inlet 24 and arent 1" an outlet 25 for hot refrigerant gas. 'I'he inlet and outlet are controlled by a conventional valve mechanism 26. Thus, in operation, as the piston 21 reciprocates, gas is drawn into the cylinder from the space within the housing 11 through the suction port 24 and hot gas under pressure is discharged through outlet port 25. The motor and compressor may be of entirely conventional construction and are lubricated in a conventional manner by circulation of the oil shown in the lower portion of the housing. A single cylinder piston-type compressor is shown in the drawings, but obviously a rotary compressor or a multi-cylinder compressor could be used as well.

In the ordinary sealed compressor unit, connections are made from the high pressure, or discharge, side of the compressor to a separate condenser where the refrigerant is cooled and liquefied and from which the liquefied refrigerant flows into a receiver and through an expansion valve to the evaporator; from the evaporator, the refrigerant gas returns to the suction side of the compressor. In such a system, the condenser and receiver are entirely separated from the compressor unit.

According to the present invention, the condenser is yformed as a unit with the compressor by means of a i cylindrical member 30 that is integrally joined to the cylindrical housing 11 by a flange 31 which may be welded to the housing as indicated at 32. The lower end of the cylindrical member 30 is welded to the horizontally extending flange 33 of the bottom 13 as indi-` cated at 34. Thus the member 30 defines an annular chamber 35 surrounding the compressor-motor unit and in direct communication with the discharge opening 25 of the compressor. The inner wall of the chamber is constituted by the housing 11.

In order to liquefy the gas in the chamber 35, any convenient cooling means may be employed. In the form of the invention shown in Figure 1, the cooling means comprises a coil 37 of tubing through which water is circulated. The water enters through inlet connection 38 and is discharged through outlet connection 39. The chamber 35 and the coil 37 thus constitute a condenser for the refrigerant gas, while the lower portion of the chamber constitutes a receiver for the liquefied refrigerant. The flow of water through the coil 37 may be controlled by any convenient means. For example, a pressure controlled valve 40 in the inlet 38 may be employed. This valve, which may be of conventional construction, is controlled by pressure from connection 41 so that water is caused to flow through the cooling coil 37 whenever the pressure within the receiver exceeds a predetermined amount. The flow of water is cut off when the pressure in the receiver is reduced below a predetermined value. Pressure controls of this type are well known.

The outlet 43 for liquid refrigerant is at the lower part of the chamber or receiver 35 and in accordance with usualpractice rmay be provided with a manually operable shut-off valve 44. From the shut-off valve, the liquid refrigerant is conducted through an appropriate conduit to a conventional expansion valve 45 or other expansion controlling device from which it flows to the evaporator indicated diagrammatically at 46. Refrigerant from the evaporator is returned through an appropriate conduit and a manually controlled shut-off valve 47 to an accumulator 48 that is on the suction side of the compressor.

Accumulator 48 is an annular chamber that surrounds the housing 11 and, at its lower part, the cylindrical member 3l?. The accumulator is formed by an outer cylindrical member 50 that is joined to the upper part of the cylindrical housing 11 as by a flange 51 which is welded as at 52 to the housing 11. The lower. end of. member 5l)- is welded as shown at 53 to the projecting horizontal ange 33 of the bottom member 13. It will be noted that the lower portion of the accumulator surrounds the receiver 35 into which the hot gases from the compressor are'discharged. The cylindrical member 30 constitutes a wall that is common to the receiver 35 and the accumulator '48; thus the accumulator is in heat exchange relation with the receiver. By reason of this construction, the cool gas on the suction side of the apparatus assists in cooling the hot gas discharged from the compressor and, it any liquid refrigerant should be returned to the suction side of the machine, it will be evaporated by heat transferred from the receiver.

It is to be noted that the suction inlet to the accumulator 4S is on one side of the apparatus Whereas the outlet 54 from the accumulator to the interior of the housing 11 is kpreferalily on the opposite side and is located near the top of the accumulator. While the outlet 54 does not need to Vbe diametrically opposite the suction inlet 47, nevertheless it should be circumferentially spaced from the suction inlet. The refrigerant gas in the housing 11 is drawn into the compressor 23 through the inlet port 24. With such an arrangement, there is no possibility ofL slugs of liquid refrigerant being drawn out of the accumulator into the housing 11 and then into the compressor 23.

The present construction lends itself advantageously to refrigeration systems in which defrosting is accomplished iby means of a bypass connection that directs hot gas from the compressor into the evaporator coils, lay-passing the condenser and the expansion valve. With my refrigeration unit, this can be accomplished readily by the provision of a by-pass outlet 56 leading from the upper portion of the receiver, and preferably adjacent the discharge port of the compressor, to a hand controlled shut-off valve 57 and a solenoid valve 58. Solenoid valve 58 may be actuated by a manual switch, by a timer control, by a frost detecting device, or in any known manner to open communication to a conduit 59 that leads to the lower portion of the evaporator coil 46, the connection being shown at 60. The conduit 59 preferably leads through a drip-tray 61 disposed beneath the evaporator coil 46. The drip-tray has a drain 62.

In operation, when defrosting is required, hot gas from the compressor flows through the normally open, manually controlled valve 57 and through the solenoid valve 58. The gas melts any accumulation of ice in the tray 61 and the frost from the evaporator coil. The gas ilows back through the suction inlet 47 into the accumulator 48. Normally, some of the refrigerant gas is condensed to liquid form as it passes through the cold evaporator coils. Any liquid returned to the accumulator runs to the bottom of the accumulator where it is eventually evaporated by the heat of the gas and liquid refrigerant under pressure in the receiver 3S. The refrigerant gas ows through the port 54 into the interior of the housing 11 and thence into the suction port 24 of the compressor 23. Thus, there is no possibility of a slug of liquid refrigerant reaching the compressor even when the unit is used in a system embodying automatic defrosting and there is no requirement for an additional accumulator or an auxiliary heat supply to evaporate refrigerant that may be condensed during the defrosting portion of the cycle. These factors make for economy of construction and eiciency of operation.`

In service, al1 of the cooling of the motor and compressor is ultimately taken care of by the heat transferred tothe water in the cooling coil 37. The motor and compressor operate in the refrigerant gas and are cooled by it as in a conventional system.

Figure 2 of the drawing illustrates a refrigeration unit embodying my invention and adapted to be cooled by air. In this form of unit the motor, compressor, receiver and accumulator are essentially the same as described in connectionmwith .Figure land the same reference characters have been applied to corresponding parts. However, in the modification shown in Figure 2, the receiver is divided by a partition 64 into an upper portion 35a and a lower portion 351:. The compressor 23 discharges directly into the upper portion 35a which is connected by a conduit 65 to a condensing coil 66 that surrounds the cylindrical housing 50. The lower end 67 of the condensing coil 66 extends through the housing member 50 and through the wall 30 of the receiver into the lower compartment 35b, of the receiver. Compartment 35h is connected to the evaporator 4and associated elements which may be substantially identical to those shown in Figure 1 and previously described, or which may take any conventional form, through a conduit 68 and a manually operated valve 69.

In order to cool the -condensing coil 66, a fan or blower indicated in general at 70 is mounted on the upper surface of the top member 12. The fan may be of any convenient type and, as shown, comprises an impeller 71 driven by an electric motor 72 and housed in a housing 73. Cooling air is drawn into the housing through a central opening 75 as indicated by the arrows and is discharged through peripheral openings 76 into an outer annular chamber 77 formed by a shroud 78 that surrounds the coil 66. The fan motor may be controlled to start operation whenever the compressor motor runs or may be controlled in any convenient manner. When the fan motor is driven, cooling air is blown down through the chamber 77, there being a plurality of outlets 76 leading to the chamber 77 at circumferentially spaced points (see Figure 4). By this means, the hot gas discharged on the high side of the compressor is condensed into liquid which flows downwardly into the lower compartment '35h of the receiver, the heat being taken away by the air passing over the condensing coil. If necessary, the coil 66 can be provided with fins or other extending surface to provide adequate heat exchange capacity.

As before, the gas from the evaporator is returned to the suction side of the compressor through a valve 47a to the accumulator 48. Any liquid refrigerant returned with the gas accumulates in the lower portion of the accumulator `and is evaporated by heat from the refrigerant in the receiver and by heat obtained from air passing on the outside of the Wall 50. Since the inlet 54 is at a high level in this modification as in the previously described form, there is no likelihood of liquid refrigerant reaching the compressor.

In the form of the invention shown in Figures 3 and 4 the general structure is essentially the same as that shown in Figure 2 except that provision is made for evaporative cooling of the condenser coil 66. Here again the same reference characters have been applied to corresponding parts. In this figure the unit is shown as being rotated 120 as compared to Figure 2 and thus the connections to the refrigeration system do not appear. However, they are identical to those illustrated in Figure 2 and the unit is adapted for use with a system such as shown in Figure i, as well as any other conventional refrigeration system.

In the form of the invention shown in Figure 3 the outer shroud 78a is stopped short of the bottom of the unit. The bottom member 13a is extended outwardly as shown at 9% and is provided with an upstanding flange 91 to form an annular chamber 92 surrounding the lower portionvof the unit. The channel is provided with a cover that is spaced from ilange 91 to provide an annular space for the discharge of air as indicated by the arrows. Channel 92 is connected to a suitable water supply through a conduit 93 controlled by a float valve 94 to maintain a substantially constant water level in the channel. Water from the channel is circulated by means of an electric motor driven pump 96 having an intake conduit 97. The pump withdraws water from the channel Y92 and delivers it through a discharge conduit 98 to a manifold 99 disposed on the exterior of the shroud 78a. Manifold 99is provided with a number ofl discharge pipes 100 which distribute water over the convolutions of the condensing coil 66. In this construction the motor driven fan 70 blows air into the shroud 78a through the connections 76 and cools the condensing coils 66 by evaporation of some of the water flowing over the coils; the water that is carried away by the air in the form of vapour is replenished through the supply conduit 93.

In this modification, as before, the refrigerant gas is returned to the accumulator chamber 48. Any liquid returning to the chamber falls to the lower portion of the accumulator where it is evaporated by heat abstracted from the refrigerant within the receiver 35a as well as from the .Water and air surrounding the shroud 78a.

It will be noted that in each of the forms of the invention illustrated herein the compressor, condenser, re* ceiver and accumulator are all incorporated in a single compact unit. The units are economical of space and economical to manufacture because of their compact design. The units lend themselves admirably to welded construction and are advantageous from the standpoints of reliability and ease of installation because no external connections are required, except for the connections to the evaporator.

The receiver, accumulator and condenser are in proper heat exchange relationship to each other and to the motor and compressor unit to improve the thermodynamic eiiiciency of the unit as compared to prior types of apparatus. The arrangement of the accumulator, which eliminates any possibility of slugs of liquid refrigerant reaching the compressor, is particularly advantageous in refrigeration systems embodying automatic defrosting cycles in which hot gas from the compressor is by-passed directly to the evaporator.

Those skilled in the art will appreciate that various changes and modications can be made in my invention without departing from the spirit and scope thereof. The essential characteristics of the invention are defined in the appended claims.

I claim:

l. A refrigeration unit co-mprising a compressor for compressing a refrigerant gas and motor for driving the compressor, a housing encompassing the motor and compressor, said compressor having a suction port communi- -cating with the interior of said housing, means for condensing the refrigerant gas discharged under pressure by said compressor, a receiver adapted to contain liqueiied refrigerant surrounding said housing, one wall of said receiver being constituted by said housing and the outer wall of said receiver being constituted by a cylindrical member surrounding said housing adjacent the lower portion thereof, an accumulator surrounding said housing and said receiver, said receiver and said accumulator having a common wall, a connection for connecting said receiver to an evaporator, a connection for connecting said accumulator to the low pressure side of said evaporator, said housing having an opening providing a passageway from said accumulator into said housing.

2. A refrigeration unit comprising a compressor for compressing a refrigerant gas, a motor for driving the compressor, a housing encompassing the motor and the compressor, a second member surrounding the lower portion of said housing and joined thereto to provide an annular chamber constituting a receiver, one wall of said receiver being constituted by said housing and the other wall being constituted by said second member, the discharge port of said compressor communicating with said receiver, a third member joined to and surrounding said housing and said second member and providing a chamber constituting an accumulator, the outer wall of said accumulator being constituted by said third member and the inner wall of said accumulator being constituted in part by said housing and in part by said second member, a connection for connecting said receiver to an evaporator, and a connection for connecting said accumulator to said evaporator.

3. A refrigeration unit comprising a compressor for compressing a refrigerant gas, a motor for driving the compressor, a housing encompassing the motor and the compressor, said compressor having a suction port communicating with the interior of said housing, a second member surrounding the lower portion of said housing and joined thereto to provide an annular chamber con-y 1stituting a receiver, the discharge port of said compressor communicating with said receiver, a third member su-rrounding said housing and said second cylindrical member and providing a chamber constituting an accumulator, said housing constituting a portion of the inner wall of said accumulator, said second member constituting the remainder of the inner wall off said accumulator and said third member constituting the outer wall of said accu-rnulator, a condenser comprising a cooling coil disposed Within said receiver for condensing the refrigerant gas therein, a connection for connecting said receiver to an evaporator, a connection for connecting said accumulator to said evaporator, whereby said accumulator receives refrigerant from said evaporator, the portion of said accumulator surrounding said second cylindrical member and said receiver being adapted to receive any liquid refrigerant returned to said accumulator, a passage from said accumulator to the interior of said housing, said passage leading from said accumulator at a level substantially above the level of said receiver and at a point spaced from said connection between said evaporator and said accumulator, whereby said accumulator acts as a separator to prevent liquid refrigerant from reaching said suction port of said compressor.

4. A refrigeration unit comprising a compressor for compressing a refrigerant gas, a motor for driving the compressor, a housing encompassing the motor and the compressor, said compressor having a suction port communicating with the interio-r of said housing, a second member surrounding a portion of said housing and joined thereto to provide an annular chamber constituting a re'- ceiver, the discharge port of said compressor communicating with said receiver, a third member surrounding said housing and said second cylindrical member and providing a sealed chamber constituting an accumulator, said housing constituting a portion of the inner wall of said accumulator, said second member constituting the remainder o-f the inner wall of said accumulator and said third member constituting the outer wall of said accumulator, a condenser comprising a coil of tubing connected to said compressor at one end and to said receiver at its other end and surrounding said accumulator and means for cooling said coil for condensing the refrigerant gas therein, a connection for connecting said receiver to an evaporator, a connection for connecting said accumulator to said evaporator, the portion of said accumulator chamber surrounding said receiver being adapted to receive any liquid refrigerant returned to said accumulator, a passage from said accumulator to interior of said housing, said passage leading from said accumulator at la level substantially above the level o-f said receiver and at a point spaced from said connection between said evaporator and said accumulator, whereby said accumulator acts as a separator to prevent liquid refrigerant from reaching said suction port of said compressor.

5. A refrigeration unit comprising a compressor for compressing a refrigerant gas, a motor for driving the compressor, a housing encompassing the motor and the compressor, said compressor having a suction port communicating'with the interior of said housing, a second member surrounding a portion of said housing and joined thereto to provide an annular chamber constituting a receiver, the discharge port of said compressor communieating with said receiver, a third member surrounding said housing and said second cylindrical member and providing a sealed chamber constituting an accumulator, said housing constituting a portion of the inner wall of said accumulator, said second member constituting the remainder of the inner wall of said accumulator and said third member constituting the outer Wall of said Yaccumulator, a condenser comprising a coil of tubing connected to said compressor at one end and to said receiver at its other end and surrounding said accumulator and means `for cooling said coil for condensing the refrigerant gas therein, said cooling means comprising a blower for circulating air over said cooling coil, aconnection for connecting saidreceiver to an evaporator, a connection for connecting said accumulator to said evaporator, the portion off said accumulator chamber surrounding said receiver being adapted to receive any liquid refrigerant returned to said accumulator, a passage from said accumulator to interior of said housing, said passage leading from said accumulator at a level substantially above the level of said receiver and at a point spaced from said connection between said evaporator and said accumulator, whereby said accumulator acts as a separator to prevent liquid refrigerant from reaching said suction port of said compressor.

6. A refrigeration unit comprising a compressor for compressing a refrigerant gas, a motor for driving the compressor, a housing encompassing the motor and the compressor, said compressor having a suction port communicating with the interior of said housing, a second member surrounding a portion of said housing and joined thereto to provide an annular chamber constituting a receiver, the discharge port of said compressor communicating with said receiver, a third member surrounding said housing and said second cylindrical member and providing a sealed chamber constituting an accumulator, said housing constituting a portion of the inner wall of said accumulator, said second member constituting the remainder of the inner wail of said accumulator and said third member constituting the outer Wall of said accumulator, a condenser comprising a coil of tubing connected to said compressor at one end and to said receiver at its other end and surrounding said accumulator and means for cooling said coil for condensing the refrigerant gas therein, and means for causing water to ilow over the exterior of said cooling coil, a connection for connecting said receiver to an evaporator, a connection for connecting said accumulator to said evaporator, the portion of said accumulator chamber surrounding said receiver being adapted to receive any liquid refrigerant returned to said accumulator, a passage from said accumulator to interior of said housing, said passage leading from said accumulator at a level substantially above the level of said receiver and at a point spaced from said connection between said evaporator and said accumulator, whereby `said accumulator acts as a separator to prevent liquid refrigerant from reaching said suction port of said compressor.

7. A refrigeration unit comprising a` compressor for compressing a refrigerant gas, a motor for driving the compressor, a housing encompassing the motor and the compressor, said compressor having a suction port communicating with the interior of said housing, a second member surrounding a portion of said housing and joined thereto to provide an annular chamber constituting a receiver, the discharge port of said compressorlcommunicating with said receiver, a third member surrounding said housing and said second cylindrical member and providing a sealed chamber constituting an accumulator, said housing constituting a portion of the inner wall of said accumulator, said second member constituting the remainder of the inner wall of said accumulator and said third member constituting the outer Wall of said accumulator, a condenser comprising a coil of tubing connected to 4said compressor at one end and to said receiver at its other end surrounding said accumulator,

means for cooling said coil for condensing the refrigerant` gas therein, a connection for connecting said receiver to an evaporator, a connection for connecting said accumulator to the low-pressure side of said evaporator and a passageway from said accumulator into said housing.

8. A' refrigeration unit comprising a compressor for lil compressing a refrigerant gas, a motor for driving the compressor, a housing encompassing the motor and the compressor, said compressor having a suction port communicating with the interior of said housing, a second member surrounding a portion of said housing and joined thereto to provide an annular chamber constituting a receiver, the discharge port of said compressor communicating with said receiver, a third member surrounding said housing and said second cylindrical member and providing a sealed chamber constituting an accumulator, said housing constituting a portion of the inner Wall of said accumulator, said second member constituting the remainder of the inner wall of said accumulator and said third member constituting the outer wall of said accumulator, a condenser comprising a cooling coil disposed within said receiver and means for circulating a coolant through said cooling coil, a connection for connecting Said receiver to an evaporator, a connection for connecting said accumulator to the low-pressure side of said evaporator and a passageway from said accumulator into 'said housing.

9. A refrigeration unit comprising a motor and a compressor, a housing surrounding said motor and compressor, a receiver for liquefied refrigerant comprising an annular chamber surrounding said housing and in communication with the high pressure side of said compressor, an accumulator surrounding said housing and having a lower portion surrounding said receiver and in heat exchange relation therewith, an evaporator, means for connecting the high pressure side of said evaporator to said receiver, means for connecting the low-pressure side of said evaporator to said accumulator, a passageway from said accumulator into said housing, and a by-pass conduit for conducting hot refrigerant gas directly from said compressor to said evaporator before said gas s condensed into a liquid.

l0. A refrigeration unit comprising a motor and a compressor, a housing surrounding said motor and compressor, said compressor having an intake port in communication with the interior of said housing, an annular receiver for refrigerant on the high pressure side of said compressor comprising an annular chamber surrounding said housing, an accumulator on the suction side of said compressor, said accumulator comprising an annular chamber surrounding said housing and having a portion surrounding said receiver and in heat exchange relation therewith, an evaporator, means for connecting said evaporator to said receiver and to said accumulator, a by-pass conduit for conducting refrigerant gas at high pressure from said compressor to said evaporator before said gas is condensed into a liquid, and a passageway connecting said accumulator to the interior of said housing.

ll. A refrigeration unit comprising a motor and a compressor, a cylindrical housing member surrounding said motor and compressor, a second cylindrical member joined to and surrounding said housing, and providing an annular chamber constituting a receiver for refrigerant on the high pressure side of said compressor, a third cylindrical member joined to and surrounding said housing and having a portion surrounding said receiver and providing an annular chamber constituting an accumulator in heat exchange relation with said receiver and in communication with the suction side of said compressor, an evaporator, means for connecting said evaporator to said receiver and to said accumulator, and a by-pass conduit for conducting refrigerant gas at high pressure from said compressor to said evaporator before said gas is condensed into a liquid.

12. A refrigeration unit comprising a motor and a compressor, a sealed housing surrounding said motor and` compressor, said compressor having an intake port in communication with the interior of said housing, a condenser surrounding said housing, a receiver for liquefied refrigerant comprising an annular chamber surrounding said housing, an accumulator surrounding said housing and having a portion surrounding said receiver and in heat exchange relation therewith, an evaporator, means for connecting said evaporator to said receiver and to said accumulator, a by-pass conduit for conducting refrigerant gas at high pressure from said compressor to said evaporator before said gas is condensed into a liquid, a passageway connecting said accumulator to the interior of said housing, said passageway being disposed at a level substantially above the lower part of said accumulator and spaced from the connection between said accumulator and said evaporator.

13. A refrigeration unit comprising a motor and a cornpressor, a housing surrounding said motor and compressor, said compressor having an intake port in communication with the interior of said housing, a second member joined to and surrounding said housing and providing an annular chamber constituting a receiver for refrigerant, said receiver being connected to the high pressure side of said compressor, a third member joined to and surrounding said housing and having a portion surrounding said receiver providing an annular chamber constituting an accumulator in heat exchange relation with said receiver, an evaporator, connections between said evaporator and said receiver and between said evaporator and said accumulator, a by-pass conduit for conducting refrigerant gas at high pressure directly from said compressor to said evaporator before said gas is condensed into a liquid, a passageway connecting said accumulator to the interior of said housing, said passageway being disposed at a level substantially above the lower part of said accumulator and spaced from the connection between said accumulator and said evaporator.

References Cited in the le of this patent UNITED STATES PATENTS 1,509,998 Geiger et al Sept. 30, 1924 1,659,163 Ruegger Feb. 14, 1928 1,717,810 Kucher July 2, 1929 1,751,209 Kucher Mar 18, 1930 2,151,564 Robinson Mar. 21, 1939 2,742,765 Anderson Apr. 24, 1956

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