Scroll machine with capacity modulation

Claims

We claim:

1. A capacity modulation system for a scroll-type compressor comprising:

a first scroll member having a first end plate and a first spiral wrap upstanding therefrom;

a second scroll member having a second end plate and a second spiral wrap upstanding therefrom, said first and second spiral wraps being interleaved to define at least two moving fluid pockets which decrease in size as they move from a radially outer position to a radially inner position;

a first fluid passage provided in said first scroll member and extending generally radially from one of said at least two moving fluid pockets to a radially outer peripheral surface of said first scroll member;

a second fluid passage provided in said first scroll member and extending generally radially from a second of said at least two moving fluid pockets to a radially outer peripheral surface of said first scroll member and circumferentially spaced from said first passage; and

a single valve member movably supported on said radially outer peripheral surface of said first scroll member and operative to substantially simultaneously open and close said first and second fluid passages to thereby modulate the capacity of said scroll-type compressor.

2. A capacity modulation system as set forth in claim 1 further including an actuating assembly, said actuating assembly being operative to move said valve member between a first de-energized position in which said first and second passages communicate with said area at substantially suction pressure to a second energized position in which said first and second passages are closed off from said area at substantially suction pressure.

3. A capacity modulation system as set forth in claim 2 wherein said actuating assembly is de-energized when said compressor is started thereby enabling use of a lower starting torque motor for driving said compressor.

4. A capacity modulation system as set forth in claim 2 wherein said actuating assembly is de-energized when said compressor is shut down.

5. A capacity modulation system as set forth in claim 2 wherein said actuating assembly is actuated by fluid pressure.

6. A capacity modulation system as set forth in claim 2, wherein said actuating assembly includes a solenoid for affecting movement of said valve member.

7. A capacity modulation system as set forth in claim 1 wherein said valve member is an annular ring.

8. A capacity modulation system as set forth in claim 7 wherein said annular ring includes first and second portions movable into and out of overlying relationship with respect to said first and second passages respectively.

9. A capacity modulation system as set forth in claim 8 wherein said first and second portions cooperate with said first scroll member to axially support said annular ring with respect thereto.

10. A capacity modulation system for a scroll-type compressor comprising:

a first scroll member having a first end plate and a first spiral wrap upstanding therefrom;

a second scroll member having a second end plate and a second spiral wrap upstanding therefrom, said first and second spiral wraps being interleaved to define at least two moving fluid pockets which decrease in size as they move from a radially outer position to a radially inner position;

a first fluid passage communicating between one of said at least two moving fluid pockets and an area at substantially suction pressure;

a second fluid passage communicating between a second of said at least two moving fluid pockets and an area at substantially suction pressure; and

a single valve member operative to substantially simultaneously open and close said first and second fluid passages to thereby modulate the capacity of said scroll-type compressor, said valve member comprising an annular ring rotatably supported on one of said first and second scroll members, said annular ring including first and second portions movable into and out of overlying relationship with respect to said first and second passages respectively, and cooperating with said one of said first and second scroll members to axially support said annular ring with respect thereto, said annular ring also including a plurality of spaced guide surfaces engageable with portions of said one of said first and second scroll members, said guide surfaces cooperating with said one scroll member to radially position said annular ring with respect thereto and to guide rotational movement thereof.

11. A capacity modulation system as set forth in claim 2 wherein said actuating assembly includes a piston movably disposed in a cylinder, said piston being connected to said valve member and a fluid line for selectively supplying pressurized fluid to said cylinder whereby said piston will operate to move said valve member in a first direction from said first position to said second position.

12. A capacity modulation system as set forth in claim 11 wherein said actuating assembly includes a return member operative to move said valve member from said second position to said first position when said supply of pressurized fluid is discontinued.

13. A capacity modulation system for a scroll-type compressor comprising:

a first scroll member having a first end plate and a first spiral wrap upstanding therefrom;

a second scroll member having a second end plate and a second spiral wrap upstanding therefrom, said first and second spiral wraps being interleaved to define at least two moving fluid pockets which decrease in size as they move from a radially outer position to a radially inner position;

a first fluid passage communicating between one of said at least two moving fluid pockets and a lower pressure area;

a second fluid passage communicating between a second of said at least two moving fluid pockets and a lower pressure area;

a single valve member operative to substantially simultaneously open and close said first and second fluid passages to thereby modulate the capacity of said scroll-type compressor; and

an actuating assembly operative to move said valve member between a first de-energized position in which said first and second passages communicate with said lower pressure area to a second energized position in which said first and second passages are closed off from said lower pressure area said actuating assembly including a piston movably disposed in a cylinder piston being connected to said valve member and a fluid line for selectively supplying pressurized fluid to said cylinder whereby said piston will operate to move said valve member in a first direction from said first position to said second position; and said cylinder communicating with a passage for venting said pressurized fluid to a lower pressure area within said compressor.

14. A capacity modulation system as set forth in claim 11 wherein said pressurized fluid is supplied from compressed refrigerant discharged by said compressor.

15. A capacity modulation system as set forth in claim 14 further including a control valve for selectively supplying pressurized fluid to said cylinder and control means operative to selectively actuate said control valve in response to sensed operating conditions.

16. A capacity modulation system as set forth in claim 2 wherein said actuating assembly includes a rack connected to said valve member and a motor driven pinion gear operative to drive said rack.

17. A capacity modulation system as set forth in claim 1 wherein said first and second passages communicate with said moving fluid pockets within 450.degree. of the outer end of first and second scroll members respectively.

18. A capacity modulation system as set forth in claim 1 further comprising a third fluid passage communicating with said one of said moving fluid pockets and a fourth fluid passage communicating with said second of said moving fluid pockets, said third fluid passage being located circumferentially inwardly from said first fluid passage and said fourth fluid passage being located circumferentially inwardly of said second fluid passage, said single valve member being operative to open and close said third and fourth fluid passages substantially simultaneously.

19. A capacity modulation system as set forth in claim 18 wherein said single valve member is movable from a first position in which said first, second, third and fourth fluid passages are open to a second position in which said third and fourth fluid passages are closed.

20. A capacity modulation system as set forth in claim 19 wherein said valve member is movable to a third position in which said first, second, third and fourth fluid passages are closed.

21. A scroll-type refrigeration compressor comprising:

a first scroll member having a first end plate and a first spiral wrap upstanding therefrom;

a second scroll member having a second end plate and a second spiral wrap upstanding therefrom, said first and second spiral wraps being interleaved to define at least two moving fluid pockets which decrease in size as they move from a radially outer position to a radially inner position;

a stationary body supporting said second scroll member for orbital movement with respect to said first scroll member, said first scroll member being supportingly secured to said stationary body;

a drive shaft rotatably supported by said stationary body and drivingly coupled to said second scroll member; p1 a driving motor operative to rotatably drive said drive shaft;

a first fluid passage provided in said first scroll member and extending generally radially from a first fluid pocket and opening outwardly along an outer peripheral surface of said first scroll member;

a second fluid passage provided on said first scroll member and extending generally radially from a second fluid pocket and opening outwardly along an outer peripheral surface of said first scroll member, in circumferentially spaced relationship from said first passage;

an annular valve ring rotatably supported on said peripheral surface in radially spaced overlying relationship to said openings of said first and second passages, said valve ring including first and second radially inwardly extending protrusions movable into and out of overlying relationship with respect to said first and second openings respectively to close and open said passages; and

an actuating assembly supported on said first scroll member, said actuating assembly being operable to effect rotary movement of said valve ring with respect to said first scroll member to thereby move said protrusions into and out of overlying relationship with said openings whereby the capacity of said compressor may be modulated.

22. A scroll-type refrigeration compressor as set forth in claim 21 wherein said protrusions are positioned on said ring so as to simultaneously open and close said passages.

23. A scroll-type refrigeration compressor as set forth in claim 22 wherein said first and second passages are positioned so as to open into said first and second fluid pockets within 360 degrees of the outer end of said first wrap.

24. A scroll-type refrigeration compressor as set forth in claim 21 wherein said first scroll member is secured to said stationary body by a plurality of circumferentially spaced bolts and said valve ring includes a plurality of arcuate cutouts around the periphery thereof, said cutouts affording access to said bolts subsequent to assembly of said valve ring to said first scroll member.

25. A scroll-type refrigeration compressor as set forth in claim 21 wherein said actuating assembly includes a housing having a cylinder therein, a piston movably disposed within said cylinder and having one end projecting outwardly from said housing, said one end being coupled to said valve ring whereby movement of said piston will effect rotary movement of said valve ring from a first position to a second position.

26. A scroll-type refrigeration compressor as set forth in claim 25 further comprising a fluid passage in said housing for conducting pressurized fluid to said cylinder to effect movement of said piston outwardly from said cylinder.

27. A scroll-type refrigeration compressor as set forth in claim 26 wherein said housing includes a first abutment surface and said valve ring includes a second abutment surface movable into engagement with said first abutment surface to limit rotational movement of said valve ring in a first direction.

28. A scroll-type refrigeration compressor as set forth in claim 26 wherein said housing includes a passage for venting pressurized fluid from said cylinder.

29. A scroll-type refrigeration compressor as set forth in claim 28 further comprising a return biasing member having one end coupled to said valving ring and operative to urge said valving ring from said second position to said first position.

30. A scroll-type refrigeration compressor as set forth in claim 26 further including a first fluid line having one end in fluid communication with compressed refrigerant discharged from said compressor and the other end connected to a solenoid valve, a second fluid line connected between said solenoid valve and said fluid passage in said housing, a control module connected to said solenoid valve and operable to actuate same from a first closed position to prevent supplying compressed refrigerant at discharge pressure to said cylinder to a second open position in which compressed refrigerant at discharge pressure is supplied to said cylinder in response to sensed operating conditions.

31. A scroll-type refrigeration compressor as set forth in claim 30 further comprising a third fluid line having one end connected to said solenoid valve and the other end in fluid communication with a suction inlet to said compressor, said solenoid valve being operative to place said cylinder in fluid communication with said suction inlet when in said first position.

32. A capacity modulation system as set forth in claim 21 further comprising a third fluid passage communicating with said one of said moving fluid pockets and a fourth fluid passage communicating with said second of said moving fluid pockets, said third fluid passage being located circumferentially inwardly from said first fluid passage and said fourth fluid passage being located circumferentially inwardly of said second fluid passage, said single valve member being operative to open and close said third and fourth fluid passages substantially simultaneously.

33. A capacity modulation system as set forth in claim 32 wherein said first protrusion is also movable into and out of overlying relationship with said third fluid passage and said second protrusion is also movable into and out of overlying relationship with said fourth fluid passage.

34. A scroll-type refrigeration compressor comprising:

a first scroll member having a first end plate and a first spiral wrap upstanding therefrom;

a second scroll member having a second end plate and a second spiral wrap upstanding therefrom, said first and second spiral wraps being interleaved to define at least two moving fluid pockets which decrease in size as they move from a radially outer position to a radially inner position;

a stationary body supporting said second scroll member for orbital movement with respect to said first scroll member, said first scroll member being supportingly secured to said stationary body;

a drive shaft rotatably supported by said stationary body and drivingly coupled to said second scroll member;

a driving motor operative to rotatably drive said drive shaft;

a first fluid passage provided in said first scroll member and extending generally radially from a first fluid pocket and opening outwardly along an outer peripheral surface of said first scroll member;

an annular valve ring rotatably supported on said peripheral surface in radially spaced overlying relationship to said opening of said first passage, said valve ring including a first radially inwardly extending protrusion movable into and out of overlying relationship with respect to said first opening to close and open said passage; and

an actuating assembly supported on said first scroll member, said actuating assembly being operable to effect rotary movement of said valve ring with respect to said scroll member to thereby move said protrusion into and out of overlying relationship with said openings whereby the capacity of said compressor may be modulated.

35. A scroll-type refrigeration compressor comprising:

a first scroll member having a first end plate and a first spiral wrap upstanding therefrom;

a second scroll member having a second end plate and a second spiral wrap upstanding therefrom, said first and second spiral wraps being interleaved to define at least two moving fluid pockets which decrease in size as they move from a radially outer position to a radially inner position;

a stationary body supporting said second scroll member for orbital movement with respect to said first scroll member, said first scroll member being supportingly axially movably secured to said stationary body;

a drive shaft rotatably supported by said stationary body and drivingly coupled to said second scroll member;

a driving motor operative to rotatably drive said drive shaft;

a first fluid passage provided in said first scroll member and extending generally radially from a first fluid pocket and opening outwardly along an outer peripheral surface of said first scroll member;

a second fluid passage provided on said first scroll member and extending generally radially from a second fluid pocket and opening outwardly along an outer peripheral surface of said first scroll member, in circumferentially spaced relationship from said first passage;

an annular valve ring movably supported on said peripheral surface in overlying relationship to said openings of said first and second passages, said valve ring including first and second opening portions movable into and out of overlying relationship with respect to said first and second openings respectively to open and close said passages; and

an actuating assembly supported on said first scroll member, said actuating assembly being operable to effect movement of said valve ring with respect to said first scroll member to thereby move said open portions into and out of overlying relationship with said openings whereby the capacity of said compressor may be modulated.

36. A scroll-type refrigeration compressor as set forth in claim 35 further comprising biasing means acting on said end plate of said first scroll member for axially biasing said first scroll member toward said second scroll member.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates generally to scroll compressors and more specifically to a capacity modulation system of the delayed suction type for such compressors.

Refrigeration and air conditioning systems are commonly operated under a wide range of loading conditions due to changing environmental conditions. In order to effectively and efficiently accomplish the desired cooling under such changing conditions, it is desirable to incorporate means to vary the capacity of the compressors utilized in such systems.

A wide variety of systems have been developed in order to accomplish this capacity modulation most of which delay the initial sealing point of the moving fluid pockets defined by scroll members. In one form, such systems commonly employ a pair of vent passages communicating between suction pressure and the outermost pair of moving fluid pockets. Typically these passages open into the moving fluid pockets at a position normally within 360.degree. of the sealing point of the outer ends of the wraps. Some systems employ a separate valve member for each such vent passage which valves are intended to be operated simultaneously so as to ensure a pressure balance between the two fluid pockets. Other systems employ additional passages to place the two vent passages in fluid communication thereby enabling use of a single valve to control capacity modulation.

The first type of system mentioned above creates a possibility that the two valves may not operate simultaneously. For example, should one of the two valves fail, a pressure imbalance will be created between the two fluid pockets which will increase the stresses on the Oldham coupling thereby reducing the life of the compressor. Further, such pressure imbalance may result in increasing operating noise to an unacceptable level. Even slight differences in the speed of operation between the two valves can result in objectionable noise generating transient pressure imbalances.

While the second type of system mentioned above eliminates the concern over pressure imbalances encountered with the first system, it requires additional costly machining to provide a linking passage across the scroll end plate to interconnect the two vent passages. Additionally, the addition of this linking passage increases the re-expansion volume of the compressor when it is operated in a full capacity mode thus reducing its efficiency.

The present invention, however, overcomes these and other problems by providing a single valving ring operated by a single actuator so as to ensure simultaneous opening and closing of the vent passages thus avoiding any possibility of even transient pressure imbalances in the fluid pockets. The valving ring of the present invention is in the form of an annular ring which is rotatably mounted on the non-orbiting scroll member and includes portions operative to open and close, one, two or more vent passages simultaneously. In one form a single actuator is provided which is operative to move the valving member preferably from an open reduced capacity position to a closed position and a return spring operates to return the valving member to a preferred open position. In another form, the return spring is omitted and the actuator operates to drive the valving member between the open and closed positions. Thus a minimum number of parts are required to accomplish the capacity modulation. Further, the capacity modulation system of the present invention will preferably be designed such that the compressor will be in a reduced capacity mode at both start up and shut down. The reduced capacity starting mode reduces the required starting torque because the compressor is compressing a substantially smaller volume of refrigerant. This reduced starting torque enables use of a lower torque higher efficiency motor. Also, reduced capacity operation at shut down reduces the potential and degree of noise generating reverse rotation of the scrolls thereby enhancing customer satisfaction. Additionally, the system of the present invention is designed such that should the actuating system fail, the compressor will be able to continue operation in a reduced or modulated capacity mode. This is desirable because under normally encountered operating conditions, the compressor will spend most of its running time in the modulated or reduced capacity mode.

Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary section view of a hermetic scroll compressor incorporating the capacity modulation system of the present invention;

FIG. 2 is an enlarged view of a portion of the compressor shown in FIG. 1 with the valving ring shown in a closed position;

FIG. 3 is a plan view of the compressor shown in FIG. 1 with the top portion of the outer shell removed;

FIG. 3a is a fragmentary view showing a portion of a modified valving member in accordance with the present invention;

FIG. 4 is a perspective view of the valving ring incorporated in the compressor of FIG. 1;

FIGS. 5 and 6 are section views of the valving ring of FIG. 4, the sections being taken along lines 5--5 and 6--6 thereof, respectively;

FIG. 7 is a fragmentary section view showing the scroll assembly forming a part of the compressor of FIG. 1, the section being taken along line 7--7 thereof;

FIG. 8 is an enlarged view of the actuating assembly incorporated in the compressor of FIG. 1, all in accordance with the present invention;

FIG. 9 is a plan view of the non-orbiting scroll with the valving ring removed therefrom, all in accordance with the present invention;

FIG. 10 is a fragmentary section view of the non-orbiting scroll shown in FIG. 9, the section being taken along line 10--10 thereof;

FIG. 11 is an enlarged detail view of a portion of the non-orbiting scroll shown in FIG. 9;

FIG. 12 is an enlarged detail view showing the interconnection between the actuating assembly and the valving ring, all in accordance with the present invention;

FIG. 13 is a fragmentary section view similar to FIG. 1 but showing another embodiment of the present invention;

FIG. 14 is an enlarged detail view of the actuating assembly incorporated in the embodiment shown in FIG. 13;

FIG. 15 is a fragmentary section view similar to that of FIG. 1 but showing yet another embodiment of the present invention;

FIG. 16 is a perspective view of a modified actuator housing, all in accordance with the present invention;

FIGS. 17-19 are all views similar to that of FIG. 7 but showing modified embodiments of the present invention; and

FIGS. 20 and 21 are views similar to that of FIG. 8 but showing two different actuating assemblies all in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings and in particular to FIG. 1, there is shown a hermetic scroll-type refrigeration compressor indicated generally at 10 and incorporating a capacity modulation system in accordance with the present invention.

Compressor 10 is generally of the type disclosed in U.S. Pat. No. 4,767,293 issued Aug. 30, 1988 and assigned to the same assignee as the present application the disclosure of which is hereby incorporated by reference. Compressor 10 includes an outer shell 12 within which is disposed orbiting and non-orbiting scroll members 14 and 16 each of which include upstanding interleaved spiral wraps 18 and 20 which define moving fluid pockets 22, 24 which progressively decrease in size as they move inwardly from the outer periphery of the scroll members 14 and 16.

A main bearing housing 26 is provided which is supported by outer shell 12 and which in turn movably supports orbiting scroll member 14 for relative orbital movement with respect to non-orbiting scroll member 16. Non-orbiting scroll member 16 is supported by and secured to main bearing housing for limited axial movement with respect thereto in a suitable manner such as disclosed in U.S. Pat. No. 5,407,335 issued Apr. 18, 1995 and assigned to the same assignee as the present application, the disclosure of which is hereby incorporated by reference.

A drive shaft 28 is rotatably supported by main bearing housing 26 and includes an eccentric pin 30 at the upper end thereof drivingly connected to orbiting scroll member 14. A motor rotor 32 is secured to the lower end of drive shaft 28 and cooperates with a stator 34 supported by outer shell 12 to rotatably drive shaft 28.

Outer shell 12 includes a muffler plate 36 which divides the interior thereof into a first lower chamber 38 at substantially suction pressure and an upper chamber 40 at discharge pressure. A suction inlet 42 is provided opening into lower chamber 38 for supplying refrigerant for compression and a discharge outlet 44 is provided from discharge chamber 40 to direct compressed refrigerant to the refrigeration system.

As thus far described, scroll compressor 10 is typical of such scroll-type refrigeration compressors. In operation, suction gas directed to lower chamber 38 via suction inlet 42 is drawn into the moving fluid pockets 22 and 24 as orbiting scroll member 14 orbits with respect to non-orbiting scroll member 16. As the moving fluid pockets 22 and 24 move inwardly, this suction gas is compressed and subsequently discharged into discharge chamber 40 via a center discharge passage 46 in non-orbiting scroll member 16 and discharge opening 48 in muffler plate 36. Compressed refrigerant is then supplied to the refrigeration system via discharge outlet 44.

In selecting a refrigeration compressor for a particular application, one would normally choose a compressor having sufficient capacity to provide adequate refrigerant flow for the most adverse operating conditions to be anticipated for that application and may select a slightly larger capacity to provide an extra margin of safety. However, such "worst case" adverse conditions are rarely encountered during actual operation and thus this excess capacity of the compressor results in operation of the compressor under lightly loaded conditions for a high percentage of its operating time. Such operation results in reducing overall operating efficiency of the system. Accordingly, in order to improve the overall operating efficiency under generally encountered operating conditions while still enabling the refrigeration compressor to accommodate the "worst case" operating conditions, compressor 10 is provided with a capacity modulation system.

The capacity modulation system of the present invention includes an annular valving ring 50 movably mounted on non-orbiting scroll member 16, an actuating assembly 52 also supported on non-orbiting scroll member 16 and a control system 54 for controlling operation of the actuating assembly.

As best seen with reference to FIGS. 2 and 4 through 6, valving ring 50 comprises a generally circularly shaped main body portion 56 having a pair of substantially diametrically opposed radially inwardly extending protrusions 58 and 60 provided thereon of substantially identical predetermined axial and circumferential dimensions. Suitable substantially identical circumferentially extending guide surfaces 62, 64 and 66, 68 are provided adjacent axially opposite sides of protrusions 58 and 60, respectively. Additionally, two pairs of substantially identical circumferentially extending axially spaced guide surfaces 70, 72 and 74, 76 are provided on main body 56 being positioned in substantially diametrically opposed relationship to each other and spaced circumferentially approximately 90.degree. from respective protrusions 58 and 60. As shown, guide surfaces 72 and 74 project radially inwardly slightly from main body 56 as do guide surfaces 62 and 66. Preferably, guide surfaces 72, 74 and 62, 66 are all axially aligned and lie along the periphery of a circle of a radius slightly less than the radius of main body 56. Similarly, guide surfaces 70 and 76 project radially inwardly slightly from main body 56 as do guide surfaces 64 and 68 with which they are preferably axially aligned. Also surfaces 70, 76 and 64, 68 lie along the periphery of a circle of a radius slightly less than the radius of main body 56 and preferably substantially equal to the radius of the circle along which surfaces 72, 74 and 62, 66 lie. Main body 56 also includes a circumferentially extending stepped portion 78 which includes an axially extending circumferentially facing stop surface 79 at one end. Step portion 78 is positioned between protrusion 60 and guide surfaces 70, 72. A pin member 80 is also provided extending axially upwardly adjacent one end of stepped portion 78. Valving ring 50 may be fabricated from a suitable metal such as aluminum or alternatively may be formed from a suitable polymeric composition and pin 80 may be either pressed into a suitable opening provided therein or integrally formed therewith.

As previously mentioned, valving ring 50 is designed to be movably mounted on non-orbiting scroll member 16. In order to accommodate valving ring 50, non-orbiting scroll member 16 includes a radially outwardly facing cylindrical sidewall portion 82 thereon having an annular groove 84 formed therein adjacent the upper end thereof. In order to enable valving ring 50 to be assembled to non-orbiting scroll member 16, a pair of diametrically opposed substantially identical radially inwardly extending notches 86 and 88 are provided in non-orbiting scroll member 16 each opening into groove 84 as best seen with reference to FIG. 3. Notches 86 and 88 have a circumferentially extending dimension slightly larger than the circumferential extent of protrusions 58 and 60 on valving ring 50.

Groove 84 is sized to movably accommodate protrusions 58 and 60 when valving ring is assembled thereto and notches 86 and 88 are sized to enable protrusions to be moved into groove 84. Additionally, cylindrical portion 82 will have a diameter such that guide surfaces 62, 64, 66, 68, 70, 72, 74 and 76 will slidingly support rotary movement of valving ring 50 with respect to non-orbiting scroll member 16.

Non-orbiting scroll member 16 also includes a pair of generally diametrically opposed radially extending passages 90 and 92 opening into the inner surface of groove 84 and extending generally radially inwardly through the end plate of non-orbiting scroll member 16. An axially extending passage 94 places the inner end of passage 90 in fluid communication with moving fluid pocket 22 while a second axially extending passage 96 places the inner end of passage 92 in fluid communication with moving fluid pocket 24. Preferably, passages 94 and 96 will be oval in shape so as to maximize the size of the opening thereof without having a width greater than the width of the wrap of the orbiting scroll member 14. Passage 94 is positioned adjacent an inner sidewall surface of scroll wrap 20 and passage 96 is positioned adjacent an outer sidewall surface of wrap 20. Alternatively passages 94 and 96 may be round if desired however the diameter thereof should be such that the opening does not extend to the radially inner side of the orbiting scroll member 14 as it passes thereover.

Actuating assembly 52 includes a piston and cylinder assembly 98 and a return spring assembly 99. Piston and cylinder assembly 98 includes a housing 100 having a bore defining a cylinder 104 extending inwardly from one end thereof and within which a piston 106 is movably disposed. An outer end 107 of piston 106 projects axially outwardly from one end of housing 100 and includes an elongated opening 108 therein adapted to receive pin 80 forming a part of valving ring 50. Elongated or oval opening 108 is designed to accommodate the arcuate movement of pin 80 relative to the linear movement of piston end 107 during operation. A depending portion 110 of housing 100 includes an enlarged diameter opening 112 therein from which a fluid passage 114 extends upwardly as shown in FIG. 8. Fluid passage 114 intersects a laterally extending passage 116 which opens into the end of cylinder. A second relatively small laterally extending passage 118 extends from fluid passage 114 in the opposite direction of fluid passage 116 and opens outwardly through an end wall 120 of housing 100. Housing 100 also includes a mounting flange 122 integrally formed therewith and projecting upwardly and laterally outwardly therefrom. Mounting flange 122 is adapted to be seated on flat 124 provided on non-orbiting scroll member 16 and includes a pair of spaced openings 126, 128 for receiving locating pins 130 and 132 respectively and a center opening for receiving a suitable securing threaded fastener 134 which is received in threaded bore 136 in non-orbiting scroll member 16. As shown in FIG. 11, locating pins 130 and 132 will initially be press fitted into suitable openings provided on flat 124 of non-orbiting scroll member 16 and serve to retain housing 100 in proper position both during assembly as well as in operation thereby eliminating the need for multiple threaded fasteners to secure same.

A suitable generally L-shaped fitting 138 is secured to shell 12 and extends outwardly therethrough the outer end being adapted for connection to a fluid line 140. An enlarged diameter opening 142 is provided in fitting 138 and is adapted to receive one end of a resilient fluid coupling 144. The opposite end of fluid coupling 144 is