US2175913A

US2175913A - Motor-compressor unit for refrigerating apparatus

Info

Publication number: US2175913A
Application number: US54991A
Authority: US
Inventors: Lawrence A Philipp
Original assignee: Nash Kelvinator Corp
Current assignee: American Motors Corp
Priority date: 1935-12-18
Filing date: 1935-12-18
Publication date: 1939-10-10
Anticipated expiration: 1956-10-10

Description

L. A. PHILIPP 2,375,33

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MOTOR-COMPRESSOR UNIT FOR REFRIGERATING APPARATUS 2 Sheets-Sheet 1 Filed Dec. 18, 1935 INVENTOR. Lib/35465 Pam/PP ATTORNEY.

2 Sheets-Sheet 2 INVENTOR. Zawgmcz 4 P/m/PP ATTORNEY.

L. A. PHlLlPP Filed Dec.

MOTOR-COMPRESSOR UNIT FOR REFRIGERATING APPARATUS @cfc. W, m9.

m w w 1.; 4 7 M w w a p J i \[J W a a V J\\\ k wz fla 0 0 w w Patented @ci. 1%, i939 NETED YATES PATENT @FHQ Lawrence A. Philipp, Detroit, Mich, assignor, by mesne assignments, to Nash-Kelvinator Corporation, Detroit,

Maryland Mich,

a corporation of Application December 18, 1935, Serial No. 54,991

3 Claims.

This invention relates to refrigerating apparatus, and more particularly to motor-compressor units for use in connection with such apparatus.

It is an object of the present invention to provide a compact and eificient compression mechanism for refrigeration purposes, in which the gas pump, or compressor, is enclosed with its driving motor in a fluid tight casing, and also to provide within the casing an improved arrangement for permitting the driving motor to attain a certain speed before the compressor assumes its working load.

Another object of my invention is to divide the fluid tight casing into a compressor or high pressure compartment and a motor, or low pressure compartment, 'which latter compartment is arranged to receive the fluid to be compressed before its admission to the compressor, and to provide a simple and effective unloading device for equalizing the pressures in said compartments during periods when the compressor is inoperative, so that high pressure fluid is supplied to the compressor upon starting operation and low pressure fluid is supplied after the motor attains a certain speed and the high pressure fluid is exhausted from the motor compartment.

Another object of the invention is to provide an improved lubricating system for moving elements of the motor compressor unit.

Still another object of the invention is to pro vide a compressor of the pendulum rotary type, having a radial abutment member rigidly attached thereto, which abutment member is arranged to operate with a flat surface contact with a single oscillating rocker, the surface contact being maintained by a yieldable push rod whereby the operation of the parts is such that a compressor of high efiiciency for gas compressing purposes is provided.

Further objects and advantages of 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: i

Fig. 1 is a view of the motor compressor unit in elevation and partly broken away, and'also shows diagrammatically a refrigerating system associated with the motor compressor unit;

Fig. 2 is a vertical section of the motor compressor unit taken along the line 2-2 of Fig. 3;

Fig. 3 is a view taken along the line 3-3 of Fig. 2, showing a portion partly broken away;

Fig. 4 is a view taken along the line 6---@ of Fig. 2;

Fig. 5 is a View. Fig. 4;

Fig. 6 is a view Fig. 3;

Fig. 7 is avertical" unloading valve;

Fig. 8 is a view Fi 7;

Fig. 9 is a vertical view in cross section of a modified form of unloading valve; and

Fig. 10 is a view along the line Ill-l0 of Fig. 9.

Referring to the drawings, numeral l0 designates, in general, a motor compressor unit which withdraws evaporated refrigerant from a refrigerant evaporator l2 through a vapor conduit l6, compresses the evaporated refrigerant and delivers same to a condenser I 6, wherein it is liquefied and from which it is delivered to a high side float mechanism I 8. The float mechanism controls thefiow of liquid refrigerant to the evaporating element l2.. The operation of the motor compressor unit is controlled by a thermostatic switch 20.

The motor compressor unit comprises, in genera], a casing 25, which is formed preferably in three sections, namely; a central section 21 and

end sections

28 and 29. The central section is provided with a tubular shaped bearing 3| in which a shaft 33 is journalled. A compressor 35 is carried on one end of the shaft 33 in a compressor compartment 31, and an electric motor 39, which includes stator 40 and rotor 42, is associated with the opposite end of the shaft 33. The stator is carried by the central casting 21, and the rotor 42 is carried ,by the shaft 33, with taken along the line 5-5 of taken along the line E6 of view in cross section of an taken along the line. 8-8 of 7 the motor 39 being disposed in a motor compartment 45. The centralsection. also includes a partition member 56 which carries bearing 3| and separatesthe motor and compressor compartments.

v The compressor is of the rotary type and includes a cylinder 50 in which'is located a piston 52. The piston is moved about the cylinder 50 by means of an eccentric portion 53, which is preferably formed integral with the shaft 33. The movement of the piston is in a clockwise direction. In order to seal the high pressure side of the pump from thelow pressure side, a blade 55 is attached to the piston 52. The blade 55 cooperates with a semi-cylindrical rocker 57. Thus, it will be noted that one side of the blade has a fiat contact with the fiat side of the rocker 57, while the curved portion of the rockerfii is arranged in slidable contact with the cylinder block 50. During operation of the compressor, the blade 55 not only slides back and forth over the rocker 51 but has a tendency to nod or oscillate within a recess 60. In order to insure a good contact between the blade 55 and the rocker 51 and a good engagement between the rocker 51 and the cylinder block, a push rod 62 has been provided. The push rod is constantly tending to urge the blade toward the rocker due to a spring 63.

During operation of the compressor, the pumping action withdraws evaporated refrigerant from the evaporator through the vapor conduit I4, whence it passes through an inlet 65 formed in the partition 46 between the motor and compressor compartments. Evaporated refrigerant passes from the inlet passage 55 through check valve I I, whence it flows through passage I2 into the motor compartment 45. In order to prevent any dust, lint or dirt from the motor windings or from the system from being introduced. intothe pump, a shield I3 has been provided within the motor compartment 45 and includes a screen 15 for filtering such dirt or lint. After the evaporated refrigerant passes into the motor compartment, it is filtered, whence it flows through a passage I6, which is formed in the partition 46, into a pump inlet 18. Thus, any oil which is pumped from the compressor into the system and into the evaporator is taken along with the evaporated refrigerant by entrainment to the motor compartment. This oil is withdrawn from the motor compartment throughthe passage I6 along with the evaporated refrigerant into the pump. The compressed refrigerant is discharged from the pump through thepump outlet 80, whence it passes through a reed valve BI into a discharge chamber 82, which has a passage 83 associated therewith and which leads to a lubricant collecting bore 85. The discharged refrigerant then passes into the compressor compartment 31, which is, as will be noted, on the high pressure side of the refrigerating system. It will also be noted that during operation of the motor compressor unit, that the motor compartment 45 contains low pressure refrigerant at a pressure equivalent'to that existing in the evaporator and return conduit I4.

In order to provide for the lubrication of the pump, a quantity of lubricant is disposed within the compressor compartment 31 to a level as indicated at 81. In view of the fact thatthis oil is under pressure, a passage 88 has been provided for conducting the oil to a bearing 90 of the compressor, whence it flows to the eccentric 53 on the shaft 33. The eccentric 53 is provided with an oil hole 9| so that lubricant may freely pass from one side of the eccentric to the'other, whence it flows to the bearing member-3| and any overflow passes into the motor compartment and is later returned to the oil reservoir in the compressor compartment by the action of the compressing unit, as previously set forth herein. In order to filter the oil before passage into the pump, a screen 95 has been provided at the head of the inlet to the passage 80.

In order that'a motor having a low starting torque may be used in this sealed motor compressor unit, it is necessary to provide some sort of unloading mechanism. Thus, an unloading valve I has been provided. The valve I00 inwill be in close thermal conductive relationship cludes a weight IOI, to which is attached a necdle valve I02, which is arranged to cooperate with the valve seat I03. During operation of the valve proper is in The valve proper compressor, the valve I02 is in engagement with its seat I03, due to the centrifugal force which moves the weight IOI towards the seat I03. Whenever the compressor is at rest, a spring I04- moves the weight towards a plug I so that the valve I02 is removed from its seat I03. In order to prevent a dashpot action within the valve housing, the weight IOI is provided with slots I06. The slots also permit the flow of oil and refrigerant along the side of weight IOI.

During the operation of the compressor unit, the valve I02 is closed and prevents the high pressure gas in the compressor compartment 35 from flowing into the motor compartment 45. However, when the compressor is at rest,'the valve I02 is open and the gas from the compressor compartment is free to flow through passages 85 and H0, through a longitudinal bore H2 in the motor compressor shaft and through valve seat I03 into the motor compartment. Thus, when the compressor is at rest, the pressures within the compressor and motor compartments equalize and the motor compartment is of suflicient size so that when the compressor resumes operation, only high pressure gas is being taken into the pump until the motor attains a certain speed, and, consequently, the pump is doing little, if any, work so that danger of burning out the motor of low starting torque is prevented However, the unloadingvalve I00 also prevents the loading of the pump until a certain speed of the motor had been attained. Thus, it is necessary for the motor to reach a certain speed so that the valve I00 closes off the passage between the compressor compartment and the motor compartment, and also it is necessary for the pump to Withdraw the high pressure gas from the motor compartment before the compressor again becomes loaded.

In order to counter-balance the unloader valve and the moving elements on the compressor, counter-weights H0 and III have been attached to the motor rotor.

The modified form of unloading valve II3, as shown in Figs. 9 and 10, operates substantially thesame as that disclosed in Figs. '7 and 8. The valve II3 includes a casing II4 having a valve port H5 and a movable valve proper H6. The the position shown in Fig. 9 during operation of the compressor so as to close off the valve port II5. Whenthe compressor is inoperative, a spring III moves the valve proper into engagement with a plug II8 so that a reduced portion H9 is opposite port II5 to thus permit the passage of fluid through port II5. I I6 is provided with cross bores I20 and I2I and a longitudinal bore I23 to establish communication between passage H2 and port I I5 when the valve I I3 is in open position.

In a system of the type disclosed herein, I prefer to use a refrigerant of the type which is somewhat miscible with the lubricant, such, for example, as CCL2F2, CI-hCl, CCLFa, CFClzH, or CCLFCIc. Thus, the refrigerant and lubricant would form a homogeneous mixture and would be such that the same would probably be, to a large extent, inseparable by mechanical agitation and require heat in order to vaporize off the refrigerant from the lubricant. In order to accomwith the lubricant stored in the reservoir provided in the compressor compartment 31. This heater element operates only when the compressor is not in operation. In order to control the operation of the heating element the same has been connected with the thermostatic switch 20 so that when the switch 20 has its contacts closed, the heater element is short circuited, and when the switch contacts are open the heater element is in circuit with the power mains where it receives current from the power mains. If desired, however, S02 may be used as the refrigerant.

In order to seal the unloading valve I00 during operation of the compressor so as to prevent possibilities of leakage between the valve proper I02 and its seat I03, any oil which is discharged by the compressor along with the compressed refrigerant, will pass into the bore 85, whence, by reason of the change of velocity, the compressed refrigerant passes upwardly into the compressor compartment and the oil entrained therewith has a tendency to drop downwardly into the passage illl and into the bore H2 of the shaft 33, when it passes to the valve proper I02. Thus, the bore and passages H0 and H2 serve as lubricant collecting and storing chambers for lubricant to be used for sealing the unloading valve H00.

From the foregoing, it will be noted that I have provided a simplified form of refrigerant pumping apparatus which may be easily manufactured and assembled and one which will operate with a high degree of emciency. It will also be noted that the higli and low pressure parts of the compression mechanism are effectively sealed by a movable blade which cooperates with a movable rocker having an elongated flat surface so as to positively prevent back flow of the refrigerant from the high pressure to the low pressure side of the system. Furthermore, it will be noted that refrigerant to be compressed is first conducted through the motor compartment whence it passes to the compressor and in so doing any oil collected in the motor compartment will be conducted to the compressor along with the refrigerant to be compressed, and this oil and re-' frigerant is discharged into the compressor compartment which is at a relatively high pressure or at condensing p essure. The oil which is discharged by the compressor is collected in a small reservoir which is in open communication with an automatic unloading valve in the motor compartment. In practice, it. has been found that such valves are noisy and due to the present arrangement, which permits flow of oil to the unloading valve, such noise is eliminated. By conducting the low pressure refrigerant through the motor compartment, it will be noted that during operation of the motor compressor unit after the motor attains a certain speed, the motor rotor is operating in the low pressure refrigerant which may have some cooling effect and because it is of low pressure it is not so dimcult for the motor to break up the fine particles of refrigerant as in cases where the motor is operating in the presence of high pressure refrigerant. During periods when the pump begins operation, the automatic unloading valve eflects equalization of pressures in the motor and compressor compartments so as to aid in starting operation under substantially no load conditions while the automatic unloading valve cooperates so as to prevent any material load being'placed upon the motor compressor until the motor has reached a certain speed. It will also be noted that I have provided an improved arrangement for separating particles of lubricant from the refrigerant contained in the reservoir in the compressor compartment.

Although only a preferred form of the invention has been illustrated, and that form described in detail, it will be apparent to those skilled in the art that various modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

I claim: 1. A. device of the character described comprising a casing having a motor compartment and a compressor compartment, said motor compartment having an inlet for refrigerant and lubricant, a motor in said motor compartment, a compressor in said compressor compartment having an outlet for discharging refrigerant into said compressor compartment, means for conducting to said compressor refrigerant and lubricant from said motor compartment, means providing a reservoir for receiving the lubricant discharged from said compressor, and means including a centrifugally operable valve arranged for periodically passing refrigerant fromsaid compressor compartment to said motor compartment, and said valve being in open communication with said reservoir for receiving lubricant to seal said valve.

2. Refrigerating apparatus comprising a compressor, a motor, a shaft connecting the motor to said compressor, said shaft having a passage, means providing a reservoir for lubricant discharged from said compressor above said passage in said shaft and in open communication with said passage, and a valve responsive to rotation of said shaft for controlling said passage and being arranged to receive said lubricant from said reservoir.

3. Refrigerating apparatus comprising a compressor, a motor, a shaft connecting the motor to said compressor, said shaft having a passage, means associated with said compressor providing a reservoir for lubricant discharged from said compressor, and arranged above said passage in said shaft and in open communication with said passage and a valve responsive to the rotation of said shaft for controlling said passage and being arranged to receive said lubricant from said reservoir.

LAWRENCE A. PHILIPP.