US3303988A

US3303988A - Compressor capacity control

Info

Publication number: US3303988A
Application number: US336543A
Authority: US
Inventors: Herman R Weatherhead
Original assignee: Chrysler Corp
Current assignee: Old Carco LLC
Priority date: 1964-01-08
Filing date: 1964-01-08
Publication date: 1967-02-14
Anticipated expiration: 1984-02-14
Also published as: GB1074429A; FR1423152A

Description

Fell 1967 H. R. WEATHERHEAD 3,303,933

COMPRESSOR CAPACITY CONTROL Filed Jan. 8, 1964 5 Sheets-Sheet 1 Feb. 14, 1967 H. R. WEATHERHEAD 3,303,983

COMPRESSOR CAPACITY CONTROL Filed Jan. 8, 1964 5 Sheets-Sheet 3 Feb. 14, 1967 H. R. WEATHERHEAD 8 COMPRESSOR CAPACITY CONTROL Filed Jan. 8. 1964 5 Sheets-Sheet 5 WMW I TTOR/VI/'.

United States Patent 3,303,988 COMPRESSOR CAPACHTY CONTROL Herman R. Weatherhead, Dayton, Ohio, assignor to Chrysler Corporation, Highland Park, Mich, a corporation of Delaware Filed Jan. 8, 1964, Ser. No. 336,543 4 Claims. (Cl. 230-31) This invention relates generally to a compressor and more particularly to means associated therewith for controlling the capacity of the compressor in relation to the demand made upon the compressor.

More specifically the invention relates to novel and improved means for use with, as for example, reciprocating compressors of the type used in refrigeration systems, which includes means actuated to hold the compressor suction valve in an inoperative position during periods of operation wherein the compressor is experiencing reduced demands.

An object of this invention is to provide, for a compressor, a novel and improved compressor unloader arrangement which has the ability to either load or unload the compressor in response to small variations in either of the control parameters of temperature or pressure.

Another object of this invention is to provide a compressor unloader arrangement which has the ability to rapidly both load and unload the compressor without hesitation and without encountering the tendency to cycle and re-cycle as between successive steps of unloading as in a compressor comprised of a plurality of cylinders.

A further object of this invention is to provide a compressor unloader arrangement which unseats the compressor suction valve in a minimum of time so as to prevent damage to the suction valve and associated mechanism, as often occurs in prior art structures, during the period in which the suction valve is being lifted or unseated by the associated unloading mechanism.

Other objects and advantages of the invention will become apparent when reference is made to the following description and accompanying drawings wherein:

FIGURE 1 is an elevational axial end view of a multiple cylinder reciprocating compressor employing means, constructed in accordance with the teachings of this invention, for both loading and unloading the compressor;

FIGURE 2 is an enlarged fragmentary cross sectional View taken generally on the plane of line 2-2 of FIG- URE l and looking in the direction of the arrows;

FIGURE 3 illustrates a fragmentary portion of the cylinder .assembly of FIGURE 2 operatively connected to an unloader mechanism, constructed according to this invention, the fragmentary cross-sectional view of which is obtained by passing a plane through either FIGURES 1 or 2 substantially as indicated by line 33 thereon;

FIGURE 4 is an enlarged fragmentary cross-sectional view taken on the plane of line 44 of FIGURE 3;

FIGURE 5 is a view similar to FIGURE 3 illustrating a second embodiment of the invention;

FIGURE 6 is an enlarged fragmentary cross-sectional view taken on the plane of line 6-6 of FIGURE 5;

FIGURE 7 diagrammatically illustrates a multiple cylinder compressor, provided with a capacity control according to this invention, as employed in, for example, an air conditioning system serving a particular area;

FIGURE 8 is a simplified schematic wiring diagram illustrating the electrical circuitry employed for actuation of the compressor capacity control; and

FIGURE 9 is a top plan view of a partial assembly of a particularly successful embodiment of a compressor capacity control arrangement for a compressor having multiple cylinders and in which successive steps of loading or unloading are desired.

Referring now in greater detail to the drawings, FIG- "ice URE 1 illustrates a radial multiple-cylinder reciprocating type compressor 10 comprised of a main housing 12 and an end cover assembly 14 secured thereto as by screws 16. A plurality of cylinder assemblies 18 are arranged in a generally radiating fashion from a crankshaft 20, suitably journalled within housing 12, and axially spaced therealong.

Cylinder heads 22 close the top of each of the cylinder assemblies 18 and may be secured as by screws 24. The compressor discharge chamber 26 is separated from the compressor suction chamber 28 by a wall or partition 30 While a wall 32 separates the suction chamber 28 from the compressor crankcase chamber 34.

A cylinder liner 36 suitably received within walls 30 and 32 slidably receives a piston 38. A connecting rod 40 pivotally secured at one end to piston 38 is provided with a bearing portion 42 at its other end secured about crankshaft 20. Other connecting rods, having bearings as indicated, for example, at 44, are connected to other pistons comprising the compressor 10.

A suction valve 46 located between the top of the cylinder liner 36 and a suction valve plate 48 is normally urged downwardly into seating engagement with liner 36 by means of a plurality of circumferentially spaced suction valve springs one of which is shown at 50.

A suction valve lift ring 52 mounted about cylinder liner 36 and movable relative thereto engages a plurality of circumferentially spaced, axially directed lift pins biased resiliently downwardly, one of which is illustrated at 54.

An annular discharge valve 56, contained generally between a discharge valve cage 58 and suction valve plate 48, is normally urged downwardly into seating engagement with suction valve plate 48 by means of a plurality of circumferentially spaced springs, one of which is shown at 60, carried generally within valve cage 58. A spring 62 serves to maintain the discharge valve cage 53, suction valve plate and cylinder liner 36 in assembled relation.

An unloader yoke and body assembly 64, constructed in accordance with this invention, is mounted on wall 32, generally about cylinder liner 36 and below the suction valve lift ring 52. During required intervals of compressor operation the yoke and body assembly is caused to lift ring 52 in order to move the cooperating abutting pins 54 upwardly thereby temporarily unseating the suction valve 46 and unloading that particular cylinder assembly of the compressor 10.

During loaded operation of the cylinder assembly, every time that piston 38 moves downwardly suction valve 46 is moved upwardly off its seat allowing the gas in the suction chamber 28 to pass through a plurality of intake ports, one of which is shown at 66, and into the interior of cylinder liner 36. As piston 3-8 is moved upwardly in the compression cycle, the compressed gas is expelled from the cylinder liner through ports 68 of suction valve plate 48 unseating annular discharge valve 56 so as to pass through passageway '70 and into the discharge chamber 26. In a multiple cylinder compressor, as illustrated in FIGURE 1, the suction chamber 28 and discharge chamber 26, although separated from each other, may of course be common to all cylinders as is well known in the art.

During unloaded operation of the cylinder assembly suction valve 46 is maintained in an upper position, as a consequence of being lifted by pins 54, thereby causing the gas within the cylinder liner 36 to be expelled through intake ports 66 back into the suction chamber, every time that the piston 38 moves upwardly, rather than through the discharge ports 68.

FIGURE 3 illustrates the unloader yoke and body as sembly 64 hydraulically connected, as by means of a suitable conduit 70, to the unloader control assembly 72, which is comprised of a cover 74, solenoid assembly 76, a port plate 78 and valve housing 84). Cover 74, port plate 78, housing 80 and seals 82 and 84 located on either side of plate 7 8 are preferably secured to each other by means of a plurality of screws 86.

Cover 74 carries a valve seat 88, provided with an, annular seal 90, and a tubular valve housing 92 secured to the cover by means of a threaded annular nut 94. A radially extending flange 96 secured to the housing 92 as, for example, by brazing, in order to prevent leakage therebetween is held against a counterbore shoulder of the cover 74 by nut 94. Consequently, the tubular housing 92, which is secured to flange 96, is urged downwardly so as to have its open end 98 held against seat 88 in sealing engagement therewith. An annular seal 100 provided between flange 96 and cover 74 prevents leakage therebetween.

The upper end of housing 92 is sealingly closed by a plug member 102 secured thereto. An axially extending post 104 formed on plug 102 carries a flange 106 which serves as an abutment for securing the housing 108 and coil 110 of solenoid assembly 76 to the tubular housing 92. That is, after the tubular housing 92 (and plunger valve 112 contained therein) is secured to cover 74 by nut 94, the annular solenoid assembly 74 is placed over the extending upper end of housing 92 and brought into axial abutment with nut 94. Thereafter, a suitable spring clip 114 may be inserted between the upper end of solenoid housing 108 and the lower surface of flange 106 in order to lock the solenoid assembly 76 to the tubular housing 92. A spring 115 contained within housing 92 and generally between valve 112 and plug 102 normally urges plunger valve downwardly into sealing engagement with seat 88.

Housing 80 has a cylindrical chamber 116 which slidably receives a regulator valve 118 therein. The innermost end of chamber 116 is in communication with a conduit 120 while the other end is in free communication with the crankcase chamber 34 of the compressor 10. The regulator valve 118 is preferably formed so as to have an axially extending stem-like portion 122 about which a spring 124 is loosely confined. The spring 124 abuts against an annular spring clip 126 so as to normall urge regulator valve 118 to the left against an abutment member 128. Whenever regulator valve 118 is held against stop 128, an annular recess 130 formed in valve 118 is placed in communication with conduit 132. A plurality of radially formed passages 134 complete communication between recess 130 and an axially directed passageway 136, formed in regulator valve 118, which by virtue of the open end of chamber 116 is in constant communication with the compressor crankcase chamber 34.

Conduit 138 (formed in cover 74) communicates between chamber 140 (which generally surrounds end 98 of tubular housing 92) and passageway 142 (in port plate 78) which communicates with, for example, the discharge conduit 144 of a suitable pump 146. Pump 146, as in the case of hermetically sealed compressors which have their motor sealed therewith, may receive its supply of oil from the compressor crankcase sump as diagrammatically illustrated at 148. In such situations, the pump 146, which may be conveniently driven by the compressor motor or any other suitable means, will deliver oil through its discharge passage 144 at a pressure which may be some relatively fixed value above suction pressure at which the crankcase chamber normally exists. For convenience this pump discharge pressure will hereafter be referred to as P while the oil sump or suction pressure will be referred to as P The unloader yoke and body assembly 64 is comprised of a yoke member 150 having arm portions 152, generally disposed around the cylinder liner 36, each of which is pivotally mounted on separate pivot members 154 carried by vertically disposed supports 156. Each of the supports 156 is preferably formed integrally with a generally semi-circular base portion 158 of the body assembly 160 which is removably secured to wall 32 as by means of suitable screws one of which is shown at 162.

Body assembly 160 also includes a generally eccentrically disposed cylinder portion 164 containing therein a piston 166 which is preferably provided with an annular seal 168. Cylinder 164 is in continual communication with conduit 70 as by a coupling-like connector 170 secured within wall 32. Connector 170 is provided with an annular seal 172, to preclude leakage, and an annular snap-ring-like retainer to prevent accidental downward displacement of the connector relative to wall 32.

The terminal ends of arms 152 and base 158 are provided with

posts

174 and 176, respectively, for receiving thereabout and containing coiled compression springs one of which is illustrated at 178.

The free ends of arms 152 also have generally spherical portions 180 formed thereon which continually abut against the lower surface 182 of lift ring 52. Each of the yoke arms 152 have upwardly directed portions 184 which are, in turn, connected to each other by means of an integrally formed laterally extending bridge portion 186 which also serves to carry an axially adjustable abutment screw 188. A nut 190 may, of course, be provided for locking abutment screw 188 to bridge 186.

FIGURE 3 illustrates the cylinder assembly 18 in a loaded condition. That is, means responsive to certain control parameters have caused an electrical signal to be impressed upon electrical leads or conductors 192 and 194 of coil resulting in the ener-gization thereof so as to cause plunger valve 112 to be lifted off of seat 88 against the resistance of spring 115. Consequently, oil at a pressure P flows through passageway 142, conduit 138 and into chamber from where it passes through ports 196 of tubular housing 92, conduit 198 of seat 88, conduit 200 of cover 74 and into passageway 202 in port plate 78. From passageway 262, the oil at a pressure P; is directed into two divergent conduits 204- and 120 (as illustrated iby FIGURE 4). Conduit 204 and the restriction means 206 contained therein will be later referred to in greater detail.

The oil, under pressure P continues through conduit 120 and into chamber 116 forcing regulator valve 118 away from stop 128 to the position generally illustrated in FIGURE 3 thereby causing valve 118 to open conduit 132 permitting oil to flow therethrough and into passageway 208 in port plate 8. Passageway 208 extends around passageway 204, so as not to intersect therewith, and communicates with a conduit 210 formed in cover 74.

The oil, still at a pressure P flows from conduit 210 through conduit 70 and into cylinder 164 ca-using piston 166 and abutment 18 8 to rise. The upward movement of abutment 188, in turn, causes counter-clockwise rotation of yoke about pivots 154 compressing spring 178 and lowering li-ft ring 52. Consequently, the resiliently biased lift pins move downwardly allowing suction valve 46 to become seated.

Whenever control parameters indicate that a sufficiently reduced demand has been placed on the compressor cylinder assembly 18, indicia responsive means cause deenergization of coil 110 thereby permitting spring 115 to seat plunger valve 112 in sealing engagement with seat 88 terminating the communication of high pressure P therethro-ugh. -Restriction means 206, comprised of a cup-like body portion 212 pressed into conduit 204, continually bleeds the oil under pressure P through a calibrated orifice 214 to the crankcase chamber 34 which is at a suction pressure of P Consequently, after plunger valve 112 is seated, the bleed action of orifice 214 results in a reduction of pressure in chamber 116 thereby enabling spring 124 to move regulator valve 118 to the left terminating further communication between the innermost end 01f chamber 116 and conduit 132. When regulator valve 118 abuts against stop 128 conduit 132 and annular recess 130 are brought into full registry with each other causing cylinder 164 of yoke body 160 to be vented to the crankcase chamber 34 by means of

conduits

70, 210, passageway 208, radial passages 134 and axial passage 136.

The venting of cylinder 164 of course causes the pressure of the actuating oil the-rein to decrease permitting spring 178 to rotate unloader yoke 150 clockwise about pivots 154. The rotation of yoke 150, in turn, causes spherical portions 180 of yoke arms 152 to lift the suction valve lift ring 52 thereby moving pins 54 upwardly unseating the suction valve 46 and unloading the compressor cylinder assembly 18.

Conduit 204 also contains a filter 216 comprised of porous sintered bronze which is of a generally hollow truncated conical configuration. The larger diameter of filter 216 is in juxtaposition with the open end of a cuplike body 212 of restriction means 206 while the smaller closed diameter is disposed upstream thereof. The sum total of the individual areas of all the individual passages for fluid flow through filter 216 is considerably greater than the area for fluid flow defined by calibrated orifice 214. Consequently, the restriction to fluid flow through conduit 264 is attributable to only orifice 214 and not the filter 216. The generally tapered axial wall portion of filter 216 permits any foreign particles, which may be carried by the actuating oil, to be washed to the side of the filter thereby effectively increasing the useful life of the filter as compared to a filter which would be placed merely directly across conduit 204 so as to have a filtering area substantially equivalent to the cross-sectional area of conduit 204.

FIGURES 5 and 6 illustrate another embodiment of the invention. All elements thereof which are like or similar to those Otf FIGURES 1, 2, 3 and 4 are identified with like primed reference numerals.

Referring in greater detail to FIGURES 5 and 6, pump discharge conduit 144' supplies actuating oil under a pressure P to a chamber 218, formed in port plate 78', which communicates between conduit 138 in cover 74' and conduit 220 in housing 8%). Whenever regulator valve 118 is moved to the position illustrated, communication between conduit 226 and a conduit 222 is completed 'by virtue of an axially extending annular recess or groove 224 formed in the outer cylindrical surface of regulator valve 118. Conduit 222 is in continual communication at one end thereof with a passageway 226, in port plate 78', which is formed generally about

passages

218 and 202 so as not to intersect therewith. Conduit 210, as its counterpart in FIGURE 3, completes communication between passageway 226 and conduit 70' which leads to cylinder 164' Olf the unloader body 160.

The elements as shown in FIGURE 5 are in positions assumed during loaded compressor operation. That is, solenoid coil 110' has been energized causing plunger valve 112 to become unseated thereby permitting actuating oil, at pressure P to flow through conduits 200', 262, and 120 into the innermost end of .cylinder 116 so as to move regulator valve 118' against the resistance of spring 124 to the position shown. During the unseated condition of plunger valve 112', oil at P also flows through filter conduit 204, filter 216' and calibrated orifice 214 in the manner previously described with reference to FIGURE 4.

Whenever the cylinder assembly 18' is to operate at an unloaded condition, solenoid coil 110 is de-energized permitting spring 115' to seat plunger valve 112. The bleed action of calibrated restriction 214 sufficiently reduces the pressure within the innermost end of cylinder 116' enabling spring 124 to move regulator valve 118 to the left against stop 128'. Such movement of valve 118 terminates the communication between conduits 220 and 222, previously established by recess 223, and places annular recess 130' in registry with conduit 222 so as to complete communication between passageway 226 and 6 axial passageway 136' which exhausts into the crankcase chamber 34'.

It will become obvious from a comparison of FIG- URES 3 and 5 that the basic distinction therebetween resides in the solenoid controlled plunger valve and associated conduits. That is, in the arrangement of FIG- URE 3, all of the oil necessary to accomplish the raising of piston 166 must flow through conduit 138, ports 196 and conduits 198. In contrast, in the arrangement of FIGURE 5, the only quantity of oil which must flow through conduit 138', ports 196' and conduit 198 is that quantity necessary to move regulator valve 118 to the position illustrated. The oil actually used for raising piston 166' flows directly from passageway 218 through conduits 220, 222 and into conduit 70'. In other words, the arrangement of FIGURE 5 is, to a great extent, a servo system with the solenoid-operated plunger valve 112' being the pilot valve and the regulator valve 118' being the slave.

The invention has been thus far disclosed and described in relation to a single cylinder assembly of a compressor. Nevertheless, it should be apparent that the invention can be practiced equally well in connection with a plurality of cylinder assemblies especially Where such a multi-cylinder compressor is to have the capability of stepped or partial unloading.

For example, FIGURE 7 schematically and diagrammatically illustrates a multi-cylinder compressor 228 with an associated air conditioning system 230 serving an area 232. Each of the compressor cylinder assemblies 234 is served by a common low pressure or suction manifold 236 by which the refrigerant is returned to the cylinder assemblies and a common high pressure or discharge manifold 238 by which the compressed refrigerant is directed to the condenser 240. The system 230 is also comprised of a refrigerant receiver 242, expansion valve 243 and evaporator 244. A temperature sensitive member 246 is operatively connected to the unloader control circuitry diagrammatically illustrated at 248 which, in turn, is electrically connected to a plurality (four are illustrated) of solenoid assemblies 76 of an unloader control assembly 72'.

FIGURE 8, a simplified schematic wiring diagram, illustrates a motor relay 250 having

conductors

252, 254 and 256 leading thereto from a suitable source of electrical energy and conductors 258, 260, and 262 leading therefrom to a motor 264 fordriving the compressor.

A sequential switching device 226 responsive to and actuated by the temperature sensing bulb 246 of FIG- URE 7, or actuated by a pressure sensing device (not shown) as in the low pressure side of the conduitry containing the refrigerant, contains electrical contacts 268, 270, and 272 respectively serially connected in conductors 274, 276 and 278. Plunger valve actuating solenoid coils lltba, b, and lltlc are respectively serially connected, as by their respective terminals 192' and 194', to conductors 278, 276 and 274. Assuming that the compressor, for which the circuitry of FIGURE 8 is intended, is a four cylinder compressor requiring a completely unloaded condition during initial starting, a fourth unloader control assembly having a plunger valve actuating solenoid coil 110d may be added and serially connected to a conductor 280. It should be noted that each of the conductors 274, 276, 278, and 280 are connected in parallel relationship with conductors 282 and 284. A time delay switch indicated generally at 286, and comprised of contacts 287, permits a controlled time delay between starting of the compressor motor and loading of the compressor. Once contacts 287 close, the particular cylinder assembly controlled by solenoid coil 110'a' will, of course, remain in a loaded condition whereas coils 110a, 110b and 110'c, depending upon compressor operating conditions, may be singly or collectively energized or de-energized in order to satisfy such operating conditions.

A control schematically illustrated at 288 as being serially connected with conductor 290 is intended to represent all safety controls including such stop and start switches as are appropriate.

The general Operation of the compressor of FIGURE 7, if provided with the circuitry of FIGURE 8, would be as follows. The start switches in control 288 would be closed thereby causing relay 250 to close so as to energize the compressor motor 264. Simultaneously, time delay switch 286 would be energized but contacts 287 would not close until after the expiration of a predetermined span of time. Consequently, solenoid coils 110a, 110b, 110's and lltld would remain in a de-energized condition thereby resulting in an unloaded condition of each of the cylinder assemblies 234.

After the expiration of a sufficient period of time, contacts 287 of time delay switch 286 would close causing the energization of solenoid coil 110d which would result in one of the cylinder assemblies 234 operating in a loaded condition. Assuming that the area 232 required maximum cooling, temperature sensing probe 246, which controls the actuation of the sequence switch 226, would have caused contacts 268, 270 and 272 to be also closed at the time of the closing of contacts. 287. Under such conditions each of the cylinder assemblies 234 would have been placed in loaded condition by the respective solenoid coils.

As the cooling requirements of area 232 decrease, temperature sensitive probe 246, at a appropriate instant, causes the opening of, for example, contacts 272 thereby de-energizing solenoid coil 110'a and reducing the output of the compressor by one-quarter. If the cooling requirements of area 232 still further decrease, temperature probe 246 will again, at an appropriate instant, cause the opening of contacts 270 thereby reducing the compressor output by another one-quarter so as to have the compressor operating at half capacity. Similarly, contacts 268 could be opened so as to reduce the compressor to only one-quarter capacity, which, in the particular illustration under consideration, would be the minimum since solenoid coil 110d is not energized or de-energized in response to signals generated by temperature probe 246. As already indicated, it should be apparent that a pressure sensing device in the low pressure side of the conduitry containing the refrigerant could be employed, in lieu of the temperature probe 246, for controlling sequence switch 266.

FIGURE 9 illustrates, in generally plan view, one particularly successful arrangement of a cover, port plate, seals and valve housing with provision being made therein for the accommodation of a plurality of solenoidoperated valve assemblies in accordance with the embodiment of the invention as disclosed by FIGURES and 6. The various details carried by either the cover, or valve housing, such as the solenoid operated valve assemblies, the regulator valves are not shown so that the conduitry can be better illustrated. Elements in FIGURE 9, which are like or similar to those of FIG- URES 5 and 6 are identified with like reference numbers sufiixed to identify, where appropriate, multiplicity of such elements. Further, for ease of understanding, each reference number will be followed by either a (C), (P) or (H) to designate that that particular element is formed in either the cover, port plate or valve housing, respectively.

Referring now in greater detail to FIGURE 9, fluid under relatively high pressure, supplied as by pump 146' of FIGURE 5, is directed to conduit 144' (C) which communicates at its other end with a transverse elongated manifold-like supply passage 218 (P) which is in constant open communication with vertically disposed conduits 220a (H), 22012 (H), 220c (H) and 220d (H). Each of said conduits 220a, 220b, 2200 and 220d respectively communicate with cylindrical chambers 116a (H), 116b (H), 116'c (H) and 116d (H) in a manner so as to be in constant communication with the annular groove of the regulator valve contained in said cylindrical chambers as illustrated in FIGURE 5.

Supply passage 218 (P) is also in constant open communication with conduits 138a (C), 138'b (C), 138's (C) and 138'd (C) which have their other ends in constant open communication with chambers 141M (C), 140% (C), 1400 (C) and 140'd (C). The flow of pressurized fluid from said chambers 140'11, 140b, 149's and 140d to the vertically disposed conduits 200a (C), 20% (C), 20% (C) and 260d (C), respectively is controlled, as illustrated in FIGURE 5, by the plunger valve 112'. Passages 20221 (P), 202'b (P), 202's (P) and 20251 (P) are respectively in constant open communication between said conduits 209a, 200b, 200a and 260d and vertically disposed conduits 12022 (H), 12-0'b (H), 1290 (H) and 120'd (H) which communicate with said cylindrical chambers 116'a, 1161), 116c and 116d as also illustrated in FIGURE 5. Said conduits 12021, 12012, 120's and 120'd, as previously described with reference to FIGURE 5, provide an avenue of communication for pressurized fluid to enter cylindrical chambers 116a, 11'6b, 116c and 116'd in order to actuate the control valves 118' therein.

Vertically disposed conduits 222a (H), 2221) (H), 2220 (H) and 222d (H), which at times are respectively placed in communication with said

conduits

220a, 220b, 22% and 220d by means of groove 224 of control valves 118, are in continual open communication with passages 226a (P), 226!) (P), 226a (P) and 2260. (P). Said passages 226a, 226b, 2260 and 226d are, in turn, in constant communication with conduits 210'a (C), 210'b (C), 210c (C) and 210'd (C) which, as illustrated in FIG- URE 5, individually communicate with a suitable conduit such as 70 for supplying pressurized fluid to piston 164' of each cylinder assembly.

Conduits 204'a (H), 204'!) (H), 204'0 (H) and 204'd (H), which, as previously described with reference to FIGURES 5 and 6, continually permit some of the relatively high pressure fluid to be bled through appropriate restriction means, respectively communicate with passages 202'a (P), 202'b (P), 202'c (P) and 202'd (P).

The various screws and tapped holes for securing the valve housing seals 84' and 82, port plate 78' and cover 74' to each other are not illustrated for purposes of clarity. However, one of the advantages of the invention, as will become evident, is the fact that these same elements can be secured to each as a functioning subassembly prior to installation in an otherwise complete compressor. Apertures 292 are provided in cover 74' in order to accommodate screws for securing the cover, and other elements secured thereto, to housing 12' of the compressor 10.

The invention as herein disclosed provides an arrangement whereby rapid loading and unloading of the compressor can be accomplished with very slight changes in temperature (or other indicia of compressor demands). In compressor unloaders of the prior art actuated by suction pressure change within the compressor, there is of necessity, upon compressor unloading, a sudden surge of suction pressure within the compressor body which causes erratic movement of the unloader regulator between steps of unloading. This, in turn, causes recycling of the unloader mechanism which results in an appreciable span of time before the mechanism and suction pressure achieve a substantially steady state operating condition. This interval of time during which cyclic instability occurs, results in excessive pounding and chattering of the suction valve often leading to failure thereof or its associated seat. The invention, in addition to its ability of rapid loading and unloading, provides stability. That is, the signal generated for initiating the unloading of any particular cylinder assembly can not be influenced or in any way impaired by the accompanying sudden change in suction pressure because of the suction pressure per se does not form a link in the circuitry for causing loading or unloading.

Another important advantage is derived by employing the restriction means 296 and the attendant bleed characteristics. That is, the bleeding action continually purges the hydraulic circuitry of any refrigerant and/or gas which might become entrained in the oil employed in the hydraulic circuitry.

As previously indicated, the ability of assembling the cover, port plate, valve housing, solenoid operated plunger valve assembly, regulator valve, bleed means and all seals into a totally functioning subassembly is still another important advantage. This enables the complete control to be both hydraulically and electrically tested for the complete range of anticipated operation and then, without any subsequent disassembly, mounted on the compressor housing and connected to the yoke and body assembly 64.

Although only two embodiments of this invention have been disclosed and described it should be apparent that other embodiments and modifications of the invention are possible within the scope of the appended claims.

I claim: I

1. Unloader means for varying the capacity of a reciprocating compressor having a casing, a first partition in the casing for dividing the compressor into a compression portion and a crankcase portion, a second partition means in the compression portion of the compressor for dividing the same into a suction chamber and a discharge chamber, means forming a cylinder in the compression portion of the compressor, a piston slidably disposed in the means forming a cylinder, a suction inlet for the means forming a cylinder in communication with the suction manifold, a discharge outlet for the means forming a cylinder in communication with the discharge chamber, suction and discharge valve means movably mounted on the suction inlet and discharge outlet to control fluid flow into and out of said cylinder, said unloader means comprising an unloader yoke and body assembly, and an unloader control assembly, said unloader body compris ing a generally semicircular arcuate base portion secured to said first partition so as to be located generally within said suction chamber and disposed in general straddling fashion about said means forming a cylinder, pivot support members carried by said base in a manner so as to be generally oppositely disposed about said means forming a cylinder, a second cylinder having an open end and being carried by said base, a second piston received in said second cylinder, said yoke comprising arm portions respectively pivotally supported on said pivot support members so as to generally straddle said means forming a cylinder, a bridge-like portion connecting said yoke arm portions and carrying an adjustably positioned motion transmitting member, at least one spring contained between said yoke arm portions and said base continually urging said yoke to rotate in a direction resulting in said motion transmitting member abutting against said second piston, an annular member closely received about said means forming a cylinder and being continually urged into engagement with said yoke arm portions, second means interposed between said annular member and said suction valve, said unloader control assembly comprising a cover member detachably secured to said casing, a port plate secured to said cover, a first gasket interposed between said port plate and said cover, a valve housing secured to said port plate and said valve housing, a second gasket interposed between said port plate and said valve housing, a source of pressurized hydraulic fluid, a cavity formed in said cover, a valve seat having a passageway formed therethrough received in said cavity, an elongated valve housing having an open end closely engaging said valve seat so as to generally circumscribe said passageway, a flange carried by said elongated valve housing, means urging said flange into sealing engagement with said cover, a plunger valve slidably received within said elongated valve housing, a second spring received within said elongated valve housing continually urging said plunger valve into sealing engagement with said valve seat and passageway, a first conduit communicating between said source of fluid and said cavity, a second conduit formed in said elongated valve housing enabling communication of said fluid from said cavity to one end of said passageway, a third cylinder formed in said first-mentioned valve housing, a regulator valve slidably received in said third cylinder, a groove formed in the periphery of said regulator valve, a third conduit formed in said regulator valve having one end in open communication with said crankcase portion, a fourth conduit formed in said regulator valve interconnecting said groove and said third conduit, a third spring received in said third cylinder continually urging said regulator valve into one of two regulator valve operating positions, a fifth conduit interconnecting said third cylinder and said passageway, a sixth conduit including restriction means interconnecting said crankcase portion and said fifth conduit, a seventh conduit interconnecting said third cylinder and said second cylinder, said regulator valve being effective upon movement by said third spring to said one position to terminate communication between said third cylinder and said seventh conduit and to complete communication between said second cylinder, seventh conduit, groove, fourth conduit, third conduit and crankcase portion, and solenoid means energized in accordance with indicia of compressor operation for at times moving said plunger valve against said second spring to permit communication between said passageway and said first conduit, said hydraulic fluid being effective whenever said communication between said passageway and said first conduit is permitted to move said regulator valve to the other of said two operating positions, said regulator valve being effective upon being moved to said other operating position to terminate 7 said communication between said seventh conduit and said crankcase and to complete communication between said fifth conduit and said seventh conduit in order to admit said hydraulic fluid to said second cylinder to force said second piston to rotate said yoke against the resisting force of said first spring thereby allowing said annular member to move toward said base in order to seat said suction valve and load said compressor.

2. Unloader means for varying the capacity of a reciprocating compressor having a casing, a first partition in the casing for dividing the compressor into a compression portion and a crankcase portion, a second partition means in the compression portion of the compressor for dividing the same into a suction chamber and a discharge chamber, means for forming a cylinder in the compression portion of the compressor, a first piston slidably disposed in the means forming a cylinder, a suction inlet for the means forming a cylinder in communication with the suction manifold, a discharge outlet for the means forming a cylinder in communication with the discharge chamber, suction and discharge valve means movably mounted on the suction inlet and discharge outlet to control fluid flow into and out of said cylinder, said unloader means comprising an unloader yoke and body assembly, and an unloader control assembly, said unloader body comprising a generally semicircular a'rcuate base portion secured to said first partition so as to be located generally within said suction chamber and disposed in general straddling fashion about said means forming a cylinder, pivot support members carried by said base in a manner so as to be generaly oppositely disposed about said means forming a cylinder, a second cylinder having an open end and being carried by said base, a second piston received in said second cylinder, said yoke comprising arm portions respectively pivotally supported on said pivot support members so as to generally straddle said means forming a cylinder, a bridgelike portion connecting said yoke arm portions and carrying an adjustably positioned motion transmitting member, at least one spring contained between said yoke arm portions and said base continually urging said yoke to rotate in a direction resulting in said motion transmitting member abutting against said second piston, an annular member closely received about said means forming a cylinder and being continually urged into engagement with said yoke arm portions, second means interposed between said annular member and said suction valve, said unloader control assembly comprising a cover member detachably secured to said casing, a port plate secured to said cover, a first gasket interposed between said port plate and said cover, a valve housing securedto said port plate and said valve housing, a second gasket interposed between said port plate and said valve housing, a source of pressurized hydraulic fluid, a cavity formed in said cover, a valve seat having a passageway formed therethrough received in said cavity, an elongated valve housing having an open end engaging said valve seat so as to generally circumscribe said passageway, a flange carried by said elongated valve housing, threadable means urging said flange into sealing engagement with said cover, a plunger valve slidably received within said elongated valve housing, a second spring received within said elongated valve housing continually urging said plunger valve into sealing engagement with said valve seat and passageway, a first conduit communicating between said source of fluid and said cavity, a second conduit formed in said elongated valve housing enabling communication of said fluid from said cavity to one end of said passageway, a third cylinder formed in said first-mentioned valve housing, a regulator valve slidably received in said third cylinder, a first groove formed in the periphery of said regulator valve, a third conduit formed in said regulator valve having one end in open communication with said crankcase portion, a fourth conduit formed in said regulator valve interconnecting said first groove and said third conduit, a second groove formed in the periphery of said regulator valve spaced from said first groove, a third spring received in said third cylinder continually urging said regulator valve into one of two regulator valve operating positions, a fifth conduit interconnecting said third cylinder and said passageway, a sixth conduit including restriction means interconnecting said crankcase portion and said fifth conduit, a seventh conduit interconnecting said third cylinder and said second cylinder, an eighth conduit interconnecting said first conduit and said third cylinder, said regulator valve being effective upon movement by said third spring to said one position to terminate communication between said third cylinder and said seventh conduit and to complete communication between said second cylinder, seventh conduit, first groove, fourth conduit, third conduit and crankcase portion, and solenoid means energized in accordance with indicia of compressor operation for at times moving said plunger valve against said second spring to permit communication between said passageway and said first conduit, said hydraulic fluid being effective whenever said communication between said passageway and said first conduit is permitted to move said regulator valve to the other of said two operating positions, said regulator valve being effective upon being moved to said other operating position to terminate said communication between said seventh conduit and said crankcase and to complete communication between said seventh conduit and said eighth conduit in order to admit said hydraulic fluid to said second cylinder to force said second piston to rotate said yoke against the resisting force of said first spring thereby allowing said annular member to move toward said base in order to seat said suction valve and load said compressor.

3. Unloader means for varying the capacity of a reciprocating compressor having a casing, a first partition in the casing for dividing the compressor into a compression portion and a crankcase portion, a second partition means in the compression portion of the compressor for dividing the same into a suction chamber and a discharge chamber, means forming a cylinder in the compression portion of the compressor, a piston slldably disposed in the means forming a cylinder, a suction inlet for the means forming a cylinder in communication with the suction manifold, a discharge outlet for the means forming a cylinder in communication with the discharge chamber, suction and dischargeyalve means movably mounted on the suction inlet and discharge outlet to control fluid flow into and out of said cylinder, said unloader means comprising an unloader yoke and body assembly, and an unloader control assembly, said unloader body comprising a base portion secured to said first partition so as to be located generally within said suction chamber and disposed generally adjacent to said means forming a cylinder, pivot support members carried by said base in a manner so as to be generally oppositely disposed about said means forming a cylinder, a second cylinder having an open end and being carried by said base, a second piston received in said second cylinder, said yoke comprising arm portions respectively pivotally supported on said pivot support members so as to generally straddle said means forming a cyhnder, a bridge-like portion connecting said yoke arm portions and carrying an adjustably positioned motion transmitting member, at least one spring contained between sa d yoke arm portions and said base continually urging said yoke to rotate in a direction resulting in said motion transmitting member abutting against said second piston, an annular member closely received about said means forming a cylinder and being continually urged into engagement with said yoke arm portions, second motion transmitting means interposed between said annular member and said suction valve, said unloader control assembly comprising a cover member detachably secured to said casing, a port plate secured to said cover, a valve housing secured to said port plate, a source of pressurized hydraulic fluid, a cavity formed in said cover, a valve seat having a passageway formed therethrough received in said cavity, an elongated valve housing having an open end closely engaging said valve seat so as to generally circumscribe said passageway, a flange carried by said elongated valve housing, means urging said flange into sealing engagement with said cover, a plunger valve slidably received within said elongated valve housing, a second spring received within said elongated valve housing continually urging said plunger valve into sealing engagement with said valve seat and passageway, a first conduit communicating between said course of fluid and said cavity, a second conduit formed in said elongated valve housing enabling communication of said fluid from said cavity to one end of said passageway, a third cylinder formed in said first-mentioned valve housing, a regulator valve slidably received in said third cylinder, a groove formed in the periphery of said regulator valve, a third conduit formed in said regulator valve having one end in open communication with said crankcase portion, a fourth conduit formed in said regulator valve interconnecting said groove and said third conduit, 9.

third spring received in said third cylinder continually urging said regulator valve into one of two regulator valve operating positions, a fifth conduit interconnecting said third cylinder and said passageway, a sixth conduit including restriction means interconnecting said crankcase portion and said fifth conduit, a seventh conduit interconnecting said third cylinder and said second cylinder, said regulator valve being eflFective upon movement by said third spring to said one position to terminate communication between said third cylinder and said seventh conduit and to complete communication between said second cylinder, seventh conduit, groove, fourth conduit, third conduit and crankcase portion, and solenoid means energized in accordance with indicia of compressor operation for at times moving said plunger valve against said second spring to permit communication between said passageway and said first conduit, said hydraulic fluid being effective whenever said communication between said passageway Y and said first conduit is permitted to move said regulator valve to the other of said two operating positions, said regulator valve being effective upon being moved to said other operating position to terminate said communication between said seventh conduit and said crankcase and to complete communication between said fifth conduit and said seventh conduit in order to admit said hydraulic fluid to said second cylinder to force said second piston to rotate said yoke against the resisting force of said first spring thereby allowing said annular member to move toward said base in order to seat said suction valve and load said compressor.

4. Unloader means for varying the capacity of a reciprocating compressor having a casing, first partition in the casing for dividing the compressor into a compression portion and a crankcase portion, a second partition means in the compression portion of the compressor for dividing the same into a suction chamber and a discharge chamber, means forming a cylinder in the compression portion of the compressor, a first piston slidably disposed in the means forming a cylinder, a suction inlet for the means forming a cylinder in communication with the suction manifold, a discharge outlet for the means forming a cylinder in communication with the discharge chamber, suction and discharge valve means movably mounted on the suction inlet and discharge outlet to control fluid flow into and out of said cylinder, said unloader means comprising an unloader yoke and body assembly, and an unloader control assembly, said unloader body comprising a base portion secured to said first partition so as to be located generally within said suction chamber and disposed generally adjacent to said means forming a cylinder, pivot support members carried by said base in a manner so' as to be generally oppositely disposed about said means forming a cylinder, a second cylinder having an open end and being carried by said base, a second piston received in said second cylinder, said yoke comprising arm portions respectively pivotally supported on said pivot support members so as to generally straddle said means forming a cylinder, a bridge-like portion connecting said yoke arm portions and carrying an adjustably positioned motion transmitting member, at least one spring contained between said yoke arm portions and said base continually urging said yoke to rotate in a direction resulting in said motion transmitting member abutting against said second piston, an annular member closely received about said means forming a cylinder and being continually urged into engagement with said yoke arm portions, second motion transmitting means interposed between said annular member and said suction valve, said unloader control assembly comprising a cover member detachably secured to said casing, a port plate secured to said cover, a valve housing secured to said port plate, a source of pressurized hydraulic fluid, a cavity formed in said cover, a valve seat having a passageway formed therethrough received in said cavity, an elongated valve housing having an open end closely engaging said valve seat so as to generally circumscribe said passageway, a flange carried by said elongated valve housing, means urging said flange into sealing engagement with said cover, a plunger valve slidably received within said elongated valve housing, a second spring received within said elongated valve housing continually urging said plunger valve into sealing engagement with said valve seat and passageway, a first conduit communicating between said source of fluid and said cavity, a second conduit formed in said elongated valve housing enabling commuication of said fluid from said cavity to one end of said passageway, a third cylinder formed in said firstmentioned valve housing, a regulator valve slidably received in said third cylinder, a groove formed in the periphery of said regulator valve, a third conduit formed in said regulator valve having one end in open communication with said crankcase portion, a fourth conduit formed in said regulator valve interconnecting said first groove and said third conduit, a second groove formed in the periphery of said regulator valve spaced from said first groove, a third spring received in said third cylinder continually urging said regulator valve into one of two regulator valve operating positions, a fifth conduit interconnecting said third cylinder and said passageway, a sixth conduit including restriction means interconnecting said crankcase portion and said fifth conduit, a seventh conduit interconnecting said third cylinder and said second cylinder, an eighth conduit interconnecting said first conduit and said third cylinder, said regulator valve being effective upon movement by said third spring to said one position to terminate communication between said third cylinder and said seventh conduit and to complete communication between said second cylinder, seventh conduit, first groove, fourth conduit, third conduit and crankcase portion, and solenoid means energized in accordance, with indicia of compressor operation for at times moving said plunger valve against said second spring to permit communication between said passageway and said first conduit, said hydraulic fluid being elfective whenever said communication between said passageway and said first conduit is permitted to move said regulator valve to the other of said two operating positions, said regulator valve being eflective upon being moved to said other operating position to terminate said communication between said seventh conduit and said crankcase and to complete communication between said seventh conduit and said eighth conduit in order to admit said hydraulic fluid to said second cylinder to force said second piston to rotate said yoke against the resisting force of said first spring thereby allowing said annular member to move toward said base in order to seat said suction valve and load said compressor.

References Cited by the Examiner UNITED STATES PATENTS 1,894,267 1/1933 Foresman 251-39 2,185,473 1/1940 Neeson 230-30 2,522,762 9/1950 Neeson 23031 2,638,265 5/1953 Newton 230-31 2,654,393 10/1953 Ghormley 25130 2,961,148 11/1960 Courtney 230-31 2,986,368 5/1961 Moore 25130 2,991,924 7/ 1961 Ramsay 23030 DONLEY I. STOCKING, Primary Examiner.

MARK NEWMAN, MARTIN P. SCHWADRON,

Examiners. W. I. KRAUSS, Assistant Examiner.

Claims

1. UNLOADER MEANS FOR VARYING THE CAPACITY OF A RECIPROCATING COMPRESSOR HAVING A CASING, A FIRST PARTITION IN THE CASING FOR DIVIDING THE COMPRESSOR INTO A COMPRESSION PORTION AND A CRANKCASE PORTION, A SECOND PARTITION MEANS IN THE COMPRESSION PORTION OF THE COMPRESSOR FOR DIVIDING THE SAME INTO A SUCTION CHAMBER AND A DISCHARGE CHAMBER, MEANS FORMING A CYLINDER IN THE COMPRESSION PORTION OF THE COMPRESSOR, A PISTON SLIDABLY DISPOSED IN THE MEANS FORMING A CYLINDER, A SUCTION INLET FOR THE MEANS FORMING A CYLINDER IN COMMUNICATION WITH THE SUCTION MANIFOLD, A DISCHARGE OUTLET FOR THE MEANS FORMING A CYLINDER IN COMMUNICATION WITH THE DISCHARGE CHAMBER, SUCTION AND DISCHARGE VALVE MEANS MOVABLY MOUNTED ON THE SUCTION INLET AND DISCHARGE OUTLET TO CONTROL FLUID FLOW INTO AND OUT OF SAID CYLINDER, SAID UNLOADER MEANS COMPRISING AN UNLOADER YOKE AND BODY ASSEMBLY, AND AN UNLOADER CONTROL ASSEMBLY, SAID UNLOADER BODY COMPRISING A GENERALLY SEMICIRCULAR ARCUATE BASE PORTION SECURED TO SAID FIRST PARTITION SO AS TO BE LOCATED GENERALLY WITHIN SAID SUCTION CHAMBER AND DISPOSED IN GENERAL STRADDLING FASHION ABOUT SAID MEANS FOR A CYLINDER, PIVOT SUPPORT MEMBERS CARRIED BY SAID BASE IN A MANNER SO AS TO BE GENERALLY OPPOSITELY DISPOSED ABOUT SAID MEANS FORMING A CYLINDER, A SECOND CYLINDER HAVING AN OPEN END AND BEING CARRIED BY SAID BASE, A SECOND PISTON RECEIVED IN SAID SECOND CYLINDER, SAID YOKE COMPRISING ARM PORTIONS RESPECTIVELY PIVOTALLY SUPPORTED ON SAID PIVOT SUPPORT MEMBERS SO AS TO GENERALLY STRADDLE SAID PIVOT SUPPORT A CYLINDER, A BRIDGE-LIKE PORTION CONNECTING SAID YOKE ARM PORTIONS AND CARRYING AN ADJUSTABLY POSITIONED MOTION TRANSMITTING MEMBER, AT LEAST ONE SPRING CONTAINED BETWEEN SAID YOKE ARM PORTIONS AND SAID BASE CONTINUALLY URGING SAID YOKE TO ROTATE IN A DIRECTION RESULTING IN SAID MOTION TRANSMITTING MEMBER ABUTTING AGAINST SAID SECOND PISTON, AN ANNULAR MEMBER CLOSELY RECEIVED ABOUT SAID MEANS FORMING A CYLINDER AND BEING CONTINUALLY URGED INTO ENGAGEMENT WITH SAID YOKE ARM PORTIONS, SECOND MEANS INTERPOSED BETWEEN SAID ANNULAR MEMBER AND SAID SUCTION VALVE, SAID UNLOADER CONTROL ASSEMBLY COMPRISING A COVER MEMBER DETACHABLY SECURED TO SAID CASING, A PORT PLATE SECURED TO SAID COVER, A FIRST GASKET INTERPOSED BETWEEN SAID PORT PLATE AND SAID COVER, A VALVE HOUSING SECURED TO SAID PORT PLATE AND SAID VALVE HOUSING, A SECOND GASKET INTERPOSED BETWEEN SAID PORT PLATE AND SAID VALVE HOUSING, A SOURCE OF PRESSURIZED HYDRAULIC FLUID, A CAVITY FORMED IN SAID COVER, A VALVE SEAT HAVING A PASSAGEWAY FORMED THERETHROUGH RECEIVED IN SAID CAVITY, AN ELONGATED VALVE HOUSING HAVING AN OPEN END CLOSELY ENGAGING SAID VALVE SEAT SO AS TO GENERALLY CIRCUMSCRIBE SAID PASSAGEWAY, A FLANGE CARRIED BY SAID ELONGATED VALVE HOUSING, MEANS URGING SAID FLANGE INTO SEALING ENGAGEMENT WITH SAID COVER, A PLUNGER VALVE SLIDABLY RECEIVED WITHIN SAID ELONGATED VALVE HOUSING, A SECOND SPRING RECEIVED WITHIN SAID ELONGATED VALVE HOUSING CONTINUALLY URGING SAID PLUNGER VALVE INTO SEALING ENGAGEMENT WITH SAID VALVE SEAT AND PASSAGEWAY, A FIRST CONDUIT COMMUNICATING BETWEEN SAID SOURCE OF FLUID AND SAID CAVITY, A SECOND CONDUIT FORMED IN SAID ELONGATED VALVE HOUSING ENABLING COMMUNICATION OF SAID FLUID FROM SAID CAVITY TO ONE END OF SAID PASSAGEWAY, A THIRD CYLINDER FORMED IN SAID FIRST-MENTIONED VALVE HOUSING, A REGULATOR VALVE SLIDABLY RECEIVED IN SAID THIRD CYLINDER, A GROOVE FORMED IN THE PERIPHERY OF SAID REGULATOR VALVE, A THIRD CONDUIT FORMED IN SAID REGULATOR VALVE HAVING ONE END IN OPEN COMMUNICATION WITH SAID CRANKCASE PORTION, A FOURTH CONDUIT FORMED IN SAID REGULATOR VALVE INTERCONNECTING SAID GROOVE AND SAID THIRD CONDUIT, A THIRD SPRING RECEIVED IN SAID THIRD CYLINDER CONTINUALLY URGING SAID REGULATOR VALVE INTO ONE OF TWO REGULATOR VALVE OPERATING POSITIONS, A FIFTH CONDUIT INTERCONNECTING SAID THIRD CYLINDER AND SAID PASSAGEWAY, A SIXTH CONDUIT INCLUDING RESTRICTION MEANS INTERCONNECTING SAID CRANKCASE PORTION AND SAID FIFTH CONDUIT, A SEVENTH CONDUIT INTERCONNECTING SAID THIRD CYLINDER AND SAID SECOND CYLINDER, SAID REGULATOR VALVE BEING EFFECTIVE UPON MOVEMENT BY SAID THIRD SPRING TO SAID ONE POSITION TO TERMINATE COMMUNICATION BETWEEN SAID THIRD CYLINDER AND SAID SEVENTH CONDUIT AND TO COMPLETE COMMUNICATION BETWEEN SAID SECOND CYLINDER, SEVENTH CONDUIT, A GROOVE, FOURTH CONDUIT, THIRD CONDUIT AND CRANKCASE PORTION, AND SOLENOID MEANS ENERGIZED IN ACCORDANCE WITH INDICIA OF COMPRESSOR OPERATION FOR AT TIMES MOVING SAID PLUNGER VALVE AGAINST SAID SECOND SPRING TO PERMIT COMMUNICATION BETWEEN SAID PASSAGEWAY AND SAID FIRST CONDUIT, SAID HYDRAULIC FLUID BEING EFFECTIVE WHENEVER SAID COMMUNICATION BETWEEN SAID PASSAGEWAY AND SAID FIRST CONDUIT IS PERMITTED TO MOVE SAID REGULATOR VALVE TO THE OTHER OF SAID TWO OPERATING POSITIONS, SAID REGULATOR VALVE BEING EFFECTIVE UPON BEING MOVED TO SAID OTHER OPERATING POSITION TO TERMINATE SAID COMMUNICATION BETWEEN SAID SEVENTH CONDUIT AND SAID CRANKCASE AND TO COMPLETE COMMUNICATION BETWEEN SAID FIFTH CONDUIT AND SAID SEVENTH CONDUIT IN ORDER TO ADMIT SAID HYDRAULIC FLUID TO SAID SECOND CYLINDER TO FORCE SAID SECOND PISTON TO ROTATE SAID YOKE AGAINST THE RESISTING FORCE OF SAID FIRST SPRING THEREBY ALLOWING SAID ANNULAR MEMBER TO MOVE TOWARD SAID BASE IN ORDER TO SEAT SAID SUCTION VALVE AND LOAD SAID COMPRESSOR.