US3671147A - Hermetic compressor - Google Patents

Abstract

A MULTI-CYLINDER HERMETIC COMPRESSOR WITH MEANS FOR VARYING ITS CAPACITY BY POSITIVELY CLOSING OFF THE FLOW OF SUCTION GAS FROM THE LOW SIDE OF THE SYSTEM TO ONE OR MORE CYLINDERS. THE SUCTION GAS IS NORMALLY DELIVERED TO A CHAMBER WHICH SUPPLIES AT LEAST ONE CYLINDER AT ALL TIMES. THE GAS THEN FLOWS THROUGH A PASSAGE TO ANOTHER CHAMBER SUPPLYING A SECOND CYLINDER OR GROUP OF CYLINDERS. A FLUID OPERATED CAPACITY CONTROL VALVE IS ARRANGED IN THIS PASSAGE TO POSITIVELY SHUT OFF FLOW TO THE SECOND CHAMBER TO PREVENT GAS FROM BEING SUPPLIED TO CYLINDERS RECEIVING GAS FROM THE SECOND CHAMBER. THE CAPACITY CONTROL VALVE IS OPERATED BY HIGH PRESSURE DISCHARGE GAS, THE FLOW OF WHICH IS CONTROLLED BY AN INTERNALLY MOUNTED SOLENOID VALVE LOCATED IN A LINE BETWEEN THE CAPACITY CONROL VALVE AND A SOURCE OF DISCHARGED GAS WITHIN THE COMPRESSOR.

Description

June 20, 1972 F. M. LAucKs ETAL 3,671,147

HERMETIC COMPRESSOR Filed Deo. 30, 1969 3 Sheets-Sheet 1 ATTO RN EY June 20, 1972 F, M, LAUCKS EI'AL 3,671,147

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tr-'WZ 12 A51 sa sie 30 64 ATTOQN EY June. 20, 1972 F. M. LAucKs Er AL 3,671,147

HERMETIC COMPRESSOR Filed Dec. 30, 1969 3 Sheets-Sheet 3 1| NVENTOQS 131 D 152 130 MMA/4a 4m/5 104 wafers www ATTORNEY United States Patent O U.S. Cl. 417-286 3 Claims ABSTRACT F THE DISCLOSURE A multi-cylinder hermetic compressor with means for varying its capacity by positively closing off the ilow of suction gas from the low side of the system to one or more cylinders. The suction gas is normally delivered to a chamber which supplies at least one cylinder at all times. The gas then liows through a passage to another chamber supplying a second cylinder or group of cylinders. A lluid operated capacity control valve is arranged in this passage to positivelyshut off llow to the second chamber to prevent gas from being supplied to cylinders receiving gas from the second chamber. The capacity control valve isoperated by high pressure discharge gas, the flow of which is controlled by an internally mounted solenoid valve located in a line between the capacity control valve and a source of discharge gas within the compressor.

CROSS REFERENCE TO RELATED APPLICATION BACKGROUND AND SUMMARY OF THE INVENTION This invention relates generally to reciprocating hermetic compressors and, more particularly, to means for varying the capacity of a multi-cylinder compressor.

A number of capacity control techniques and means for unloading one or more cylinders within a compressor have been described in the prior art. One well known technique is that of holding open the suction valve so that the suction gas is not subjected to the work capable of being done on it by the piston. The suction gas enters the cylinder during the suction stroke and is forced back into the suction plenum during the discharge stroke. Another technique, which is similar to the one utilized in the present invention, s referred to as suction gas throttling. In this system, some means are provided for controlling the ow of suction gas from the evaporator to the compressor. If the flow is modulated, it often causes overheating of the compressor due to the thermodynamic losses inherent in suction gas throttling. The present invention utilizes a system which completely cuts ofI" the gas flow from the low side of the system to the gas working space. In such case, heating of the cylinder is restricted to that which is generated by the friction of the piston working in the cylinder.

Mechanisms for controlling the flow in the manner just described have been suggested in the prior art. For example, in U.S. Pat. 3,061,176 issued to A. 1J. Nicholas et al. on Oct. 30, 1962, there is described a compressor in which the cylinder is provided with an annular sleeve completely surrounding the same. The sleeve is adapted to be moved, by means of a hydraulic actuator, to a position which closes off theflow of gas from the suction Patented June 20, 1972 "ice manifold to the suction valve. One problem which is inherent in a compressor of this type is that it is diicult to obtain the proper sealing of the suction gas flow control sleeve. The sleeve has a diameter somewhat greater than the cylinder and any cocking or misalignment of the sleeve may cause gas leakage.

In the present invention, the suction gas ilow control valve is positive sealing and is completely incorporated within the housing containing the cylinders and the crank shaft. By providing a casting with integral partitions appropriately located within the space surrounding the cylinders, independent suction gas chambers can be used to supply particular cylinders. Flow passages can then be conveniently formed between the chambers; and a valve positioned within these passages can thus be constructed in a very simple manner. This permits the use of small diameter valves and valve seats which assure adequate gas sealing. Moreover, the number of parts required to accomplish positive suction gas cut-off is greatly minif mized. In fact, the llow control valve for each section of the compressor merely comprises a simple sleeve valve and a spring to bias the valve in an open position.

Accordingly, it is a principal object of the invention to provide a capacity control system particularly suited for a multi-cylinder hermetic compressor in which the liow passages and the ow control valve are contained in the cylinder housing section of the compressor.

Another object of the invention is to provide a compressor having partitions between certain cylinders so that independent control of a single cylinder is possible.

Another object of the invention is to provide a capacity control in accordance with the above stated object which can be constructed at low cost and which will operate in a trouble free manner, thus requiring little or no maintenance.

Still another object of the invention is to provide a capacity control system in which the gas throttling losses are minimized, thereby assuring a cooler operating compressor.

Additional objects and advantages will be apparent from reading the following detailed description taken in conjunction with the drawings. v

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 4 is a cross-section view ta'ken alon ln 4 4 of FIG. 3. g l e DETAILED DESCRIPTION OF THISl INVENTION Referring rst to FIG. 1, there is shown a compressor which is completely enclosed within a hermetically sealed shell 10, normally fabricated by using a lower half 12 and a dome 14. Suction gas inlet connection 16 at the upper end of the dome delivers suction gas to the interior of the compressor shell.

The compressor comprises a lower body or housing section 18 containing the cylinders 20, 21, 22 and 23; an

electric motor 24, mounted on the upper section body 26; a crank shaft 28 driven by the motor; and connecting rods 30 driving pistons 32. While the compressor illustrated utilizes four cylinders, it is obvious that any configuration utilizing two or more cylinders may be constructed `without departing from the principles of the invention.

The suction gas, after entering through the inlet connection 16, passes downwardly through the motor stator 34 and rotor 36 to effect cooling thereof, the gas being constrained to ow through the motor by means of a shroud 38 which rests on the upper body section 26. The gas passing through the motor ows through a pair of ports, 40, 41 in the upper body (only one of which is shown in FIG. l) and then down into a pair of chambers surrounding certain of the cylinders.

As best shown in FIGS. 2 and 3, the cylinder jackets are integrally cast with the lower housing section 18 in a staggered array; and each includes a pair of passages 46 extending longitudinally of the axis of the cylinder permitting the gas to flow into a suction gas plenum 48 formed between the distal portion of the cylinder jacket, provided with a flange 50, and the head 52. The valve plate assembly 54 is constructed of a series of laminated plates which form a plurality of suction gas passages '56 leading to suction valve 58 and a discharge valve 60 communieating with a series of circumferentially spaced discharged ports 62.

During the discharge stroke, with suction valve 58 closed, the gas is compressed by the piston 32 until the gas has suflicient pressure to open the discharge valve 60 and release it into the head. Each of the heads `52 is interconnected with a tubular conduit 64 leading to a muffler assembly 66 surrounding the motor housing and which is connected to a discharge line 68 leading outside of shell \10. The entire compressor unit is suspended inside the shell by means of a series of spring mounts 70 including a lower support 72 attached to the inside of the shell and springs 74 receiving mounting tubes 76 on the upper body section 26.

Attention is now directed to FIG. 3 which shows in more detail the lower body section containing the cylinders. It will be noted that the casting from which the lower body is formed includes a plurality of vertical walls 80, `81, 82 and 83 which function as partitions to separate all four cylinders. These partition walls thus form separate chambers 84, 85, 86 and 87 associated with cylinders 20, 21, 22 and 23 respectively. Between certain pairs of chambers, for example, between chambers 8S and 86, there is a thickened wall section or boss 90 which is provided with a bore 92 receiving a flow control valve 94. The suction gas is always fed through the two ports 40 and 41 (which would open into the area bounded by dotted lines in FIG. 3) in the upper body into the chambers 85 and 87 which supply suction gas to cylinders 21 and 23 respectively. However, in order to pass from. chamber 85 to chamber 86, the gas must How through a port 96 (FIG. 4) into the bore 92' and downwardly through another port 98 which opens into chamber 86.

The other valve I95, arranged in partition wall 80, controls the flow of gas from chamber 87 to chamber 84 in the same fashion. The valve elements 94 and 95, which are moveable within bores 92, are each biased to an open position by a resilient member such as spring 100. The chambers 102 and 103 above valve elements 94, 95 communicate with a source of high pressure fluid, such as the discharge gas, by means of a conduit 104 leading from the muifler 66 to a solenoid valve 106 which is selectively energized through electrical conductors 108 extending outside the shell.

Lines 110 and 111 connect solenoid valve 106 with chambers 102 and [103 respectively through passages 112 and 113 which intercept relieved areas 114, 115 providing flow passages between the upper and lower housing sections above valve elements 9'4, 95.

The solenoid valve 106 may be of any conventional type having a valve body 116 having ports 117, 118 and 119 and a moveable spool 130 having passages 131 and 132. In the spool position shown in FIG. 3, passage 131 interconnects ports 118 and 119. Port 118 is connected to a pair of fluid lines 120 and 121 leading respectively to suction gas chambers 86 and 84 via ports 122 and 123. Port 119 is connected to flow control valves 94 and 95 through tluid lines i110 and 111. Thus, passage 131 allows the pressure in valve operating chambers 102 and 103 to equalize with the pressure in suction gas chambers 86 and 84 permitting spring 100 to return the valves to their open position.

When valve spool 130 is shifted to the left (as viewed in FIG. 3), passage 132 conducts gas at discharge pressure from line 104- to port 119* and then through lines 110 and 111 to close the valves. While one solenoid valve may be used to operate both of the ow control valves within the compressor, it is obvious that individual solenoid valves could be provided. In this way, selective control of each of the pairs of cylinders can be achieved.

OPERATION Full capacity- When operating under full capacity, the suciton gas flows down into the motor and through the two ports 40, 41 in the upper body and into chambers 85 and 87. When the ow control valve 94 is biased to its open position by spring 100, the suction gas flows in chamber 85 through the port 96 in the valve housing boss past valve 94 and into chamber 86 through a port 98 on the opposite side of the valve housing boss. If the ow control valve 95 in wall is also open, gas ow from chamber 8-7 to chamber 84 will be in the same manner. In this way, al1 cylinders are supplied with gas which then flows through passages 46 into the suction plenums 48' and then through the suction valves 58 and into the cylinders. During the discharge stroke of pistons 32, the gas is forced into each of the heads 52 and up through tubes 64 into the muffler 66, and then out through the discharge line 68.

Partial capacity When the operator requires reduced capacity, he actuates the solenoid valve 106 which causes high pressure gas from the muler to be directed to the chambers 102, 103 above the valves 94, 95 by way of line 104, port 117, passage 132, port 119 and lines 110 and 111. The pressure acting on the top of the valves overcomes the spring force and closes the valves against the seats at the lower end of bores 92, 93. This closes olf the tlow of gas from chamber to chamber 86 (and from chamber 87 to chamber 84), thus completely stopping the flow of gas to cylinders 20 and 22. The compressor then continues to operate with only cylinders 21 and 23 functioning.

When it is required to return to full capacity, the solenoid valve is deactivated, returning the spool to the position shown in FIG. 3'. This allows the high pressure gas in chambers 94 and 95 to bleed back through lines 120, 121, port 118, passage 131, port 119' and lines 110, 111 and equalize the pressure with that of suction ygas charnbers 86, 84. With the pressure equalized, the spring 100 returns valves 94, to the open full capacity position.

While this invention has been described in connection with a certain specific embodiment thereof, it is to be understood that this is by way of illustration and not by way of limitation; and the scope of the appended claims should be construed as broadly as the prior art will permit.

What is claimed is:

1. A hermetic compressor comprising a housing having at least a first and second cylinder provided therein; a hermetically sealed shell surrounding said housing; a piston received in each cylinder adapted to reciprocate therein; a cylinder head positioned at the end of each said cylinder; a suction valve and a discharge valve associated with each of said cylinder heads for respectively admitting a uid to be compressed in said cylinder and for discharging the compressed fluid from said cylinder; means delining independent rst and second chambers surrounding said rst and second cylinders and communicating respectively with the suction valves of said rst and second cylinders, said chamber defining means including a common partition wall separating said rst and second chambers; means defining a fluid passage in said common partition wall providing uid communication between said irst and second chambers; valve means cooperating with said fluid passage to control fluid ow between said iirst and second chambers; and means for delivering suction gas into said first chamber; whereby suction gas to said second cylinder may be controlled by said valve means.

2. A compressor as defined in claim 1, including operator means for actuating said valve means, said operator means including an electrically actuated valve adapted to selectively direct high pressure gas from compressor discharge to said valve means for actuating the same.

3. A compressor as defined in claim 1, wherein said housing is constructed of two complementary housing sections including a iirst section containing said cylinders and a second section receiving suction gas; a motor adapted to drive said pistons supported in said second housing section; and means for causing said suction gas to ow through said motor in heat exchange relation.

References Cited UNITED STATES PATENTS 1,081,176 12/1913 Wainwright 417-2286 1,117,394 11/1914 Joleen 4l7-295 2,350,537 6/1944 Scott 417-295 3,448,918 6/1969 Cawley 417-371 CORNELIUS I. HUSAR, Primary Examiner I. I. VRABLIK, Assistant Examiner U.S. C1. X.R. 417--295, 371

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