Scroll compressor assembly having oil distribution and support feature

A horizontal scroll compressor assembly for compressing a working fluid and lubricated with oil includes a housing, an interior surface, and a suction sump for collected oil located in the suction plenum. A compression mechanism has an orbital scroll member having a thrust surface axially superposed with the housing and having an oil distribution channel. Oil from the suction sump is received into the distribution channel and delivered to locations between the superposed surfaces during movement of the orbital scroll member. A method for distributing oil in a scroll compressor assembly includes: receiving oil from a suction sump into an oil distribution channel located in the thrust surface of an orbital scroll member; pumping oil along the oil distribution channel to locations between the thrust surface and a superposed housing surface; and lubricating a thrust surface interface with oil.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a scroll-type compressor assembly for compressing a working fluid and lubricated with an oil, for use in an air conditioning system, and particularly to a scroll compressor assembly for use in an automotive air conditioning system, and to features for distributing oil within scroll compressor assemblies and using the oil for hydrodynamically separating and supporting relatively moving surfaces therein.

2. Description of the Related Art

Scroll-type compressor assemblies for automotive air conditioning systems are well-known in the art. A compressible working fluid such as a refrigerant gas is received into the compressor assembly housing at a suction pressure and discharged therefrom at a relatively higher discharge pressure. In automotive air conditioning systems, a scroll compressor assembly typically has a drive shaft whose rotation axis is generally horizontal and driven by the engine crankshaft through a drive belt coupled to the engine crankshaft pulley, which serves as a rotative power source. The compressor drive shaft is coupled to a compression mechanism within the compressor housing, which may be defined by front and rear casings. The compression mechanism of a scroll compressor assembly typically has an orbital scroll member coupled to the drive shaft and a nonorbital scroll member with which it is operably engaged. The orbital scroll member is driven in a generally circular orbit about the drive shaft rotation axis relative to the nonorbital scroll member.

The orbital scroll member includes a plate with a flat, inner surface that is perpendicular to the rotation axis and an involute wrap integral with the plate and extending out from the inner surface. The cooperating nonorbital scroll member includes a plate with a flat, inner surface that interfaces and is parallel to the inner surface of the orbital scroll member, and an involute wrap integral with its plate that extends from its inner surface. The wraps and flat, inner surfaces of the orbital and nonorbital scroll members cooperate to form fluid pockets which are bound by adjacent surfaces of the interengaged scroll members. These boundaries are established by line contacts between the intermeshed wraps, and contact between the axial tips of the intermeshed wraps and the inner surfaces of the scroll member plates against which the wrap tips are slidably engaged. A seal is normally provided in a groove formed in the axial tip of each involute scroll wrap, to seal between the wrap and the inner surface of the adjacent scroll member plate against which it slides. The axial tip seals are provided to accommodate thermal expansion of the scroll members, and separation therebetween that may result from the forces induced by the compressed fluid in the fluid pockets. An example of a prior such scroll compressor assembly is described in U.S. Pat. No. 5,346,376 (Bookbinder et al.) issued Sep. 13, 1994, the disclosure of which is expressly incorporated herein by reference.

The working fluid at substantially suction pressure, and in which substantially incompressible lubricating oil is entrained, is received in a compression mechanism inlet between the scroll members at a radially outward location. The working fluid/oil admixture received by the compression mechanism is captured within the fluid pockets defined by the interengaged scroll wraps as the orbital scroll member moves about the shaft rotation axis relative to the nonorbital scroll member. The entrained oil lubricates and cools the interengaged scroll members.

During compressor operation, as the orbital scroll member is driven by the rotating shaft, the contact lines and the fluid pockets defined between the intermeshed wraps move along the surfaces of the wraps toward the centers of the cooperating scroll members. The fluid pockets become smaller in volume as they move along the wraps toward the centers of the scroll members, and the working fluid in the fluid pockets is compressed. Thus, the interengaged orbital and nonorbital scroll members define the compression mechanism, and the fluid pockets define compression chambers of the compression mechanism in which the pressure of the contained working fluid/oil admixture is raised from substantially suction pressure to a relatively higher, substantially discharge pressure. A fluid discharge aperture is provided near the center of the nonorbital scroll member, providing a passageway through which the compressed admixture is expelled from the compression mechanism at substantially discharge pressure.

The orbital scroll member plate has an outer face that is located on the outside of the compression mechanism and opposite its flat, inner surface. Defined on the outer face is a flat thrust surface that is substantially parallel with the inner surface. Opposing the axial forces induced by the compressed admixture within the compression mechanism is a planar thrust washer disposed between the thrust surface of the orbital scroll member and a superposed, flat, rear-facing surface of the front casing of the housing. The thrust washer may be retained against movement relative to the front casing, and may include apertures that, with the rear-facing front casing surface, define pockets in which oil is disposed; the oil in these oil pockets lubricates the sliding interface between the thrust washer and the orbital scroll member thrust surface. Such a thrust washer/thrust surface interface is disclosed in above-mentioned U.S. Pat. No. 5,376,376. Despite the presence of such oil pockets, the compressor assembly may still experience frictional losses due to the sliding engagement of the orbital scroll member thrust surface and the thrust washer, particularly if oil is not adequately replenished to the oil pockets.

Conventional thrust bearing assemblies employing needle roller bearings or ball bearings may be positioned between the thrust surface, and the thrust washer or the rear-facing surface of the front casing to axially support the orbital scroll member relative to the housing. Often, such thrust bearing assemblies, though intended to reduce frictional losses, either do not adequately accommodate the orbital motion of the thrust surface relative to the thrust washer or front casing surface, or add significantly to the complexity and/or cost of the compressor assembly. Furthermore, such thrust bearing assemblies have moving parts, the introduction of which may contribute to potential durability concerns in a compressor assembly, particularly if the thrust bearing assemblies are inadequately lubricated.

It would be beneficial if, during compressor operation, lubricating oil were continually distributed to the interface between the orbital scroll member thrust surface and the thrust washer, and was also used for hydrodynamically separating and supporting the orbital scroll member thrust surface relative to the thrust washer and the front casing. Such an improvement would reduce frictional losses without introducing additional complexity or cost, or the potential durability concerns often associated with incorporating additional moving parts.

SUMMARY OF THE INVENTION

The present invention provides the benefits of facilitating oil distribution to the interface between the thrust surface of the orbital scroll member and the thrust washer, for lubricating their interface and hydrodynamically separating and supporting the orbital scroll member relative to the thrust washer and the front casing, with the oil. The improvement reduces frictional losses in the compressor assembly without increasing its complexity or cost, or raising durability concerns associated with the introduction of additional moving parts, and axially supports the orbital scroll member relative to the housing during compressor operation.

A scroll compressor assembly according to the present invention includes a nonorbital scroll member and a cooperating, driven orbital scroll member mounted inside a housing. An orbital scroll member drive shaft is journaled in the compressor housing for rotation about a drive shaft rotation axis, and is operably connected to the orbital scroll member. The housing includes a suction plenum into which is received working fluid at substantially suction pressure and that defines an oil sump (the “suction sump”) in which lubricating oil is disposed. The orbital scroll member moves in a circular orbit about the shaft rotation axis within the suction plenum, relative to the housing and the nonorbital scroll member. The scroll members include end plates with parallel flat, inner surfaces and intermeshed involute wraps which cooperate to form fluid pockets, in which is received working fluid in which lubricating oil is entrained. An anti-rotation mechanism prevents rotation of the orbital scroll member relative to the housing and the nonorbital scroll member, and permits its orbital movement relative thereto.

As the drive shaft propels the orbital scroll member, the sealed fluid pockets move toward the centers of the cooperating scroll members and become smaller in volume. As the fluid pockets decrease in volume the fluid in the fluid pockets is compressed to relatively higher pressures. The scroll members thus define a compression mechanism in which the working fluid/oil admixture is received into the fluid pockets, which are compression chambers, at substantially suction pressure and is compressed to substantially discharge pressure as the fluid pocket volume decreases. A fluid discharge aperture or passageway is provided near the center of the nonorbital scroll member for the passage of the working fluid/oil admixture from between the interengaged scroll members into a discharge plenum located in the housing.

The compressor housing rear casing has an interior surface, and the nonorbital scroll member has a rear face. The nonorbital scroll member rear face and the rear casing interior surface cooperate to form the discharge plenum of the compressor assembly. The discharge plenum receives the compressed fluid/oil admixture from between the intermeshed scroll wraps via the fluid discharge aperture at substantially discharge pressure. A compressor discharge port is provided in the rear casing for the delivery of compressed fluid at a discharge pressure from the discharge plenum to the remainder of the refrigerant system. Oil that may become separated from the compressed working fluid/oil admixture in the discharge plenum, and not delivered to the system, is received in an oil sump (the “discharge sump”) located in the discharge plenum. The discharge sump and the suction plenum are in fluid communication, and oil collected in the discharge sump is urged into the suction plenum. Oil received into the suction plenum from the discharge sump tends to either mix with working fluid received into the suction plenum via the suction port or flow into the suction sump located in the suction plenum. Oil entrained in the working fluid received into the suction plenum either remains admixed with the working fluid, or separates therefrom and becomes deposited on surfaces within the suction plenum or is collected in the suction sump.

The thrust surface of the orbital scroll member is provided with an annular groove into which oil from the suction sump is received and conveyed to the thrust surface/thrust washer interface. The groove thus forms an oil distribution channel by which oil from the suction sump is conveyed to that interface, replenishes the oil pockets, and is forced between the thrust surface and the thrust washer.

The annular oil distribution channel may include a plurality of arcuate grooves or groove segments interconnected through spaces defined in the orbital scroll member that accommodate the anti-rotation mechanism of the compressor assembly. One of these spaces may be located at least partially below the surface level of oil in the suction sump, from which it receives oil that is distributed by the oil distribution channel. The spaces accommodating the anti-rotation mechanism may be toroidal and define circular tracks that move in unison with the orbital scroll member, orbitally about cylindrical members whose locations relative to the housing are fixed. The cylindrical members may be pins, or in the form of needle roller bearing assemblies disposed on the pins. The orbital movement of the circular track receiving oil from the suction sump, about its respective cylindrical member, tends to force oil received from the suction sump into at least one of a pair of groove segments interconnected through the toroidal space. Oil forced from that space into only one of the groove segments connected to the space tends to be conducted in a single circular direction through the oil distribution channel from the space. Oil forced from that space into both of the groove segments connected to the space tends to be conducted from the space in opposite directions through the oil distribution channel. Oil that is distributed by the channel to the interface between the thrust surface and the thrust washer lubricates the interfacing surfaces and replenishes the oil pockets.

During compressor operation, the buildup of oil pressure in the annular distribution channel, in part due to oil flow resistances through its groove(s) and the interface between the thrust surface and thrust washer, hydrodynamically supports the orbital scroll member axially away from the thrust washer and the rear-facing surface of the front casing. Oil leaked from between the thrust surface/thrust washer interface is recollected in the suction sump.

The present invention provides a horizontal scroll compressor assembly for compressing a working fluid and lubricated with an oil. The compressor assembly includes a housing having an axis, an interior surface, and suction and discharge ports. Located in the housing are a suction plenum for receiving working fluid substantially at a suction pressure through the suction port, a discharge plenum from which working fluid substantially at a discharge pressure is dischargeable through the discharge port, and a suction sump for collected oil. The suction sump is located in the suction plenum. A compression mechanism is disposed in the housing for compressing an admixture of working fluid and oil. The compression mechanism includes an orbital scroll member and a nonorbital scroll member, the scroll members interengaged for defining a compression chamber therebetween into which the admixture is receivable from the suction plenum for compression. The compression mechanism has a discharge aperture for passing compressed admixture from the compression chamber to the discharge plenum. The orbital scroll member has a thrust surface in axial superposition with the housing interior surface, and movement about the axis relative to the housing and the nonorbital scroll member. The thrust surface is provided with an oil distribution channel extending at least partially about the axis, and oil from the suction sump is receivable into the oil distribution channel. Oil in the distribution channel is urged therealong and delivered to locations between the axially superposed thrust and housing interior surfaces during movement of the orbital scroll member.

In accordance with one aspect of the present invention, the compressor assembly includes a thrust washer disposed between the superposed surfaces, the thrust surface and the thrust washer having movement relative to each other. A further aspect of the present invention is that the thrust washer is provided with a plurality of apertures, the apertures and the housing interior surface defining oil pockets in which oil delivered through the oil distribution channel to locations between the superposed surfaces is deposited.

In accordance with another aspect of the present invention, in the compressor assembly the thrust surface and the housing interior surface are axially separable by hydrodynamic forces in oil delivered by the distribution channel to locations between the superposed surfaces during the movement of the orbital scroll member.

In accordance with another aspect of the present invention, in the compressor assembly the orbital scroll member is axially supportable away from the housing interior surface by hydrodynamic forces in oil delivered by the distribution channel to locations between the superposed surfaces during the movement of the orbital scroll member.

In accordance with another aspect of the present invention, the compressor assembly includes an anti-rotation mechanism through which the orbital scroll member and the housing are coupled. The orbital scroll member is provided with a plurality of spaces partially defining the anti-rotation mechanism, a lowermost one the spaces disposed in the suction sump and being receivable of oil from the suction sump; the oil distribution conduit is fluidly connected to that space. A further aspect of the present invention is that that space has at least one cylindrical surface, and the anti-rotation mechanism includes a cylindrical member disposed in that space. The cylindrical surface of that space is moved about the cylindrical member, and movement of oil in the lowermost space is induced by the anti-rotation mechanism. Oil from the suction sump receivable into that space is forced from that space into the oil distribution channel during the movement of the orbital scroll member. Furthermore, another aspect of the present invention is that that space is toroidal and has a pair of concentric cylindrical surfaces between which the cylindrical member is located. Moreover, another aspect of the present invention is that the oil distribution channel includes at least two groove segments fluidly interconnected through the toroidal space. Oil receivable into the toroidal space from the suction sump is forced into at least one of the groove segments and pumped along the oil distribution channel during the movement of the orbital scroll member. Further still, an aspect of the present invention is that the oil distribution channel includes two or more groove segments arranged about the axis, an end of one groove segment interconnected to an end of another groove segment through the toroidal space.

In accordance with another aspect of the present invention, in the compressor assembly the oil distribution channel includes an elongate groove segment. A further aspect of the present invention is that the elongate groove segment has uniformly spaced edges and a floor located therebetween. A further aspect of the present invention is also that the oil distribution channel includes a plurality of elongate groove segments, an end of one groove segment fluidly interconnected with an end of another groove segment within the orbital scroll member. An additional aspect of the present invention is that the compressor assembly includes an anti-rotation mechanism through which the housing and the orbital scroll member are coupled, and wherein the fluidly interconnected groove segment ends are interconnected through a space located in the orbital scroll member and partially defining the anti-rotation mechanism. Furthermore, another aspect of the present invention is that the space is at least partially located in the suction sump and is receivable of oil from the suction sump. Moreover, another aspect of the present invention is that the anti-rotation mechanism includes a pair of concentric cylindrical surfaces between which at least a portion of the space is located, and a cylindrical member having a fixed location about the axis relative to the housing, the cylindrical member diametrically extending between the concentric cylindrical surfaces. Movement of oil in the space is induced by relative movement between the concentric cylindrical surfaces and the cylindrical member. Oil from the suction sump receivable into the space is forced from the space and into the oil distribution channel during the movement of the orbital scroll member. Further still, an aspect of the present invention is that the cylindrical member is a needle roller bearing assembly on which at least one of the concentric cylindrical surfaces rides during the movement of the orbital scroll member.

The present invention further provides a method for distributing oil in a scroll compressor assembly including: receiving oil into an oil distribution channel located in the thrust surface of an orbital scroll member; pumping oil along the oil distribution channel to locations between the thrust surface and a superposed housing surface; and lubricating a thrust surface interface with oil pumped to locations between the thrust surface and the superposed housing surface.

In accordance with one aspect of the present invention, the method also includes supporting the orbital scroll member away from the housing surface that superposes the thrust surface with hydrodynamic forces in the oil delivered by the oil distribution channel to locations between the thrust surface and the superposed housing surface.

In accordance with another aspect of the present invention, the method also includes receiving oil from a suction sump into a space located in the thrust surface of the orbital scroll member; inducing movement to oil received in the space with a member of an anti-rotation mechanism located in the space; forcing oil received into the space from the suction sump into the oil distribution channel with the anti-rotation mechanism.

There has thus been outlined, rather broadly, certain features of an exemplary embodiment of the invention in order that the detailed description thereof may be better understood, and in order that the present contribution to the art may be better appreciated. Additional or alternative features of an embodiment of the invention are described in further detail below. Before explaining an embodiment of the invention in detail, however, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangement of the components described above or set forth in the following detailed description of the best mode of the invention illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The compressor and clutch assembly20shown inFIG. 1includes a scroll-type compressor assembly22and an attached clutch assembly24. The scroll compressor assembly22includes a generally cylindrical compressor housing26having inter-sealed front and rear casings28and30that are parts of the housing. Generally, axial and radial directions mentioned herein are with reference to the housing26. The front and rear casings28and30are respectively provided with mating surfaces32and34, and are affixed to each other by bolts36to define the housing26. A compressor fluid inlet or suction port38and a compressor fluid outlet or discharge port40are provided in the housing26. During compressor operation, a compressible working fluid, such as a refrigerant gas, is received at a suction pressure by the suction port38, and is expelled a relatively higher, discharge pressure from the discharge port40. The magnitudes of the suction and discharge pressures, and the differentials therebetween, vary considerably with different system operating conditions.

The compressor housing26is axially divided into a suction plenum42in fluid communication with the suction port38, and a discharge plenum44in fluid communication with the discharge port40. As used herein, “fluid communication” is understood to mean that the uninterrupted flow of a gas or liquid is facilitated between elements said to be in fluid communication.

An orbital scroll member50and a nonorbital scroll member52are interengaged and mounted within the housing26. The scroll members50and52include end plates54and56with parallel, interfacing, flat, inner surfaces58and60, and involute wraps62and64extending therefrom, respectively. The involute wraps62and64are intermeshed and contact each other along contact lines66,68,70and72and the adjacent inner surfaces58and60to form closed fluid pockets or compression chambers74of variable volume, as shown inFIG. 7. The interengaged scroll members50,52thus define a compression mechanism76. Compressed fluid is expelled from the compression mechanism76via a passageway78, such as a discharge aperture78, centrally located in the nonorbital scroll member52.

As shown, tip seal grooves79may be provided in the scroll wraps62,64and have axial tip seals80which float therein. The tip seals80slidably engage the inner surfaces58,60of the scroll members50,52. The tip seals80also improve compressor efficiency, and accommodate the differences in thermal expansion between the radially inner portions of the involute wraps62and64where temperatures are highest during compressor operation and at their radially outer portions where temperatures are lowest during compressor operation. Further, the tip seals80accommodate a small amount of axial movement between the scroll members50,52. Typically, the tip seals80also reduce wear and improve sealing between the axial tips of the involute wraps62and64and flat surfaces58and60on end plates54and56.

Within the housing26, the nonorbital scroll member52is secured to the rear casing30with bolts81extending through clearance holes82in the rear casing30and threaded into corresponding blind, tapped holes84provided in the rear face86of the nonorbital scroll member52, which is opposite the flat surface60of its end plate54. The discharge plenum44is sealed relative to the clearance holes82. The nonorbital scroll member rear face86and the interfacing, interior surface88of the rear casing30are provided with axially projecting bosses which define abutment surfaces90and92brought into compressive engagement directly or through an intermediate gasket (not shown) when the bolts81are tightened.

The cylindrical outer peripheral surface94of the nonorbital scroll member52is provided with circumferential grooves96in which o-ring seals98are disposed. The seals98are engaged with the mating, cylindrical, inner peripheral surface100of the rear casing30that radially interfaces the nonorbital scroll member surface94. Thus, the nonorbital scroll member52is fixed relative to the housing26and, with the front and rear casings28,30assembled, the nonorbital scroll member52axially partitions or separates the housing26into the suction plenum42and the discharge plenum44.

It can thus be understood that: during compressor operation the suction plenum42contains working fluid at substantially suction pressure and the discharge plenum44contains working fluid at substantially discharge pressure; the suction plenum42is in fluid communication with the compressor suction port38and the inlet to the compression mechanism76, and the discharge plenum44is in fluid communication with the compressor discharge port40; and the fluid entering the inlet of the compression mechanism76is captured in the compression chambers74defined by the interleaved wraps62,64of the scroll members50,52during their relative movements, compressed, and discharged from the compression mechanism76into the discharge plenum44via the passageway defined by the discharge aperture78.

The discharge plenum44in the depicted embodiment defines a radially central discharge chamber102, into which is received the working fluid/oil admixture compressed by the compression mechanism76, and a radially surrounding exhaust chamber104. Referring toFIGS. 3 through 5, the axially projecting bosses of the rear face86of the nonorbital scroll member52and the front-facing interior surface88of the rear casing30define a mating pair of continuous, C-shaped walls106and108which axially abut and together partially enclose the generally cylindrical discharge chamber102. The C-shaped walls106and108axially abut directly or through an intermediate gasket (not shown). A reed-type check valve110is employed to prevent the backflow of compressed fluid from the discharge plenum44into the compression mechanism76through the passageway defined by the discharge aperture78. In the depicted embodiment, the reed valve110is mounted on the rear face86of the end plate56of the nonorbital scroll member52. A ramped valve stop112attached to the nonorbital scroll member52limits the opening movement of the valve110. Alternatively, the valve stop112may be formed on a boss (not shown) projecting from the front-facing interior surface88of the rear casing30within the discharge chamber102.

The scroll compressor assembly22has an orbital scroll member drive assembly120that includes a drive shaft122, such as the depicted crankshaft122, journaled in the front casing28for rotation about a shaft rotation axis124, which extends axially relative to the housing26. The crankshaft122has a cylindrical stub shaft portion126that revolves about the shaft rotation axis124. The centerline of the stub shaft portion126is parallel with and offset from the shaft rotation axis124. A cylindrical, inertial balance weight128is mounted to the crankshaft122, and has a through bore130extending between its axially opposite ends into which the stub shaft portion126extends. The crankshaft122and the balance weight128are cooperatively interfitted such that the balance weight128rotates with the crankshaft122about the shaft rotation axis124. The outer cylindrical surface of the balance weight128defines a cylindrical crank132having a centerline axis134that revolves in a circular orbit about the shaft rotation axis124. The crank axis134is parallel with and offset from the shaft rotation axis124. The axes124and134are offset by a distance equal to the orbit radius Ro, of the orbital scroll member50relative to the nonorbital scroll member52. The cylindrical crank132is received in, and is rotatably coupled through a bearing136to, a cylindrical hub138centrally-located on and extending from the front face140of the orbital scroll member end plate54. The cylindrical, central hub138is an integral part of the orbital scroll member50, and is concentric with the cylindrical crank132about the axis134. Thus, the axis134is the central axis of both the crank132and the hub138. Rotation of the crankshaft122thus imparts orbital motion to the orbital scroll member50about the shaft rotation axis124at orbit radius Ro.

The crankshaft122extends forward along the shaft rotation axis124, away from the compression mechanism76to its front end142, and out of the suction plenum42through the front casing28, so that the front end142can be coupled to and driven by a rotative power source (not shown) through the clutch assembly24. In a well-known manner, the crankshaft122and the front casing28are mutually sealed against working fluid and oil leakage from the compressor housing26by a shaft seal disposed about the crankshaft122.

Referring toFIG. 2, the clutch assembly24includes a clutch hub assembly144rotatably fixed to the crankshaft front end142, a pulley assembly146having a bearing148rotatably mounted to the front casing28, and a selectively energizable electromagnetic coil assembly150affixed to the front casing28. The clutch hub assembly144and the pulley assembly146are rotatable about the axis124. The toroidal coil assembly150is generally centered about the axis124and surrounds the pulley bearing148. The coil assembly150is itself surrounded by the sheave152of the pulley assembly146. With the compressor and clutch assembly20operatively installed, the rotative power source (e.g., the engine crankshaft pulley, not shown) is continuously coupled to the pulley assembly146via a drive belt (not shown) that engages the pulley sheave152. Movement of the drive belt drivingly rotates the pulley assembly146about the axis124relative to the compressor housing26.

The clutch assembly24is biased into a disengaged state when the coil assembly150is nonenergized. In the disengaged state, the clutch hub assembly144is elastically biased into a position in which its rear-facing clutch surface154is spaced from the front-facing clutch surface156of the pulley assembly146. The location of clutch surface156is generally fixed axially relative to the housing26. In the disengaged state, the clutch hub assembly144and the pulley assembly146are uncoupled, and the shaft122is not driven. When the coil assembly150is electrically energized, the clutch assembly24is brought into its engaged state, in which the clutch surface154of the clutch hub assembly144is electromagnetically forced against its bias and into contact with the clutch surface156of the pulley assembly146. In the engaged state of the clutch assembly24, the interfacing clutch surfaces154and156are frictionally coupled for rotation in unison about the axis124, thereby operably coupling the rotative power source and the compressor drive shaft122for driving the compression mechanism76.

An anti-rotation mechanism160is mounted to and couples the front casing28and the orbital scroll member50. The anti-rotation mechanism160of the scroll compressor assembly22is similar to that disclosed in above-mentioned U.S. Pat. No. 5,346,376 except as herein described. The anti-rotation mechanism160prevents rotation of the orbital scroll member50relative to the housing26while allowing the orbital scroll member50to move orbitally relative to the nonorbital scroll member52about the shaft rotation axis124. The orbital scroll member50moves with the crank132and thus moves relative to the nonorbital scroll member52in a circular orbit about the shaft rotation axis124. The distance of the relative orbital movement of the interleaved wraps62,64is at radius Ro. The interleaved wraps62,64define, and then reduce the volume of, the compression chambers74as the compression chambers74move away from the inlet of the compression mechanism76and toward the central discharge aperture78located in the nonorbital scroll member52.

The anti-rotation mechanism160includes a plurality of large, blind, first bores162in the front face140of the orbital scroll member50that are spaced radially outboard of the hub138and open toward the front casing28. In the depicted embodiment, four such first bores162, designated first bores162a,162b,162c, and162d, are included, and are circumferentially spaced equidistantly about the orbiting scroll member hub138, at a common radial distance from the hub's central axis134, which coincides with the crank axis134. As shown, one of these first bores162is positioned vertically below the others in the operating orientation of the scroll compressor assembly22. In the depicted embodiment, first bore162ais so positioned and remains located substantially directly below the crank axis134throughout rotation of the crankshaft122in the operating orientation. A cup164is pressed into and seated against the bottom of each blind first bore162. Each cup164has a circular edge or rim165that is spaced from the orbital scroll member front face140within the respective first bore162, as best seen inFIGS. 8A and 8B. A first pin166is pressed through an opening in the center of each cup164and into a blind second bore168in the orbital scroll member50. Each second bore168is concentric with its respective first bore162and has a relatively smaller diameter. Alternatively, each first pin166could be an integral part of its cup164, as shown. The first pins166and the cups164have concentric cylindrical surfaces that cooperate to define a toroidal space170in each first bore162. Each toroidal space170defines a circular track170about its respective first pin166.

Second pins172are pressed into mating, blind, third bores174in the planar rear-facing surface176of the front casing28, which superposes the orbital scroll member front face140. Each of the third bores174corresponds to one of the first bores162in the orbital scroll member50. Each cylindrical second pin172has an axis parallel with shaft axis124and defines a cylindrical member172that extends into a respective toroidal space170. The diameter of each second pin172, or at least of the portion of it that projects into space170, may be such that it extends substantially between the concentric cylindrical surfaces of the first pins166and the cups164. Optionally, a hollow cylindrical member such as a needle roller bearing assembly178having an axis parallel with the shaft axis124may be pressed onto the end of each second pin172, as shown. In the depicted embodiment, each roller bearing assembly178is received in a respective toroidal space170, with bearing outer diameter substantially extending between the concentric cylindrical surfaces of the first pin166and the cup164.

Relative to the orbital scroll member50, the second pin172and, if present, its optional needle roller bearing assembly178received within each first bore162orbits in a circle defined by the toroidal space170inside of its cup164, and about its first pin166. Thus, relative to the housing26, the first pin166within each cup164moves in a circular orbit about the circumference of the respective cylindrical member (i.e., about the second pin172or its optional roller bearing assembly178) disposed in the respective circular track170. These circular orbits are substantially equivalent to the distance of the orbit radius Ro. The cylindrical inner peripheral surface of each cup164thus rides on the outer circumference of the respective cylindrical member disposed therein, such as a portion of a second pin172projecting from housing front casing surface176, or a needle roller bearing assembly178rotatably mounted about a second pin172as shown.

A thrust washer180is mounted on the rear-facing surface176of the front casing28. The thrust washer180is disposed between the axially superposed surfaces of the orbital scroll member front face140and the front casing28. The thrust washer180of the scroll compressor assembly22is similar to that disclosed in above-mentioned U.S. Pat. No. 5,346,376. The planar thrust washer180has parallel, opposite sides and is preferably made from a steel stamping. The front-facing side surface181of the thrust washer180abuts the rear-facing surface176of the front casing28, thereby preventing frontward movement of the thrust washer180within the housing26. Fasteners such as third pins182are pressed through first apertures184in the thrust washer180and into mating, blind bores (not shown) in the rear-facing surface176of the front casing28, thereby fixing the position of the thrust washer180relative to the housing26. The exposed ends of the third pins182are flush with or recessed relative to the rear-facing side surface185of the thrust washer180. Additionally, several second apertures186are provided in the thrust washer180. The second apertures186cooperate with the planar rear-facing surface176of the front casing28to define a plurality of oil pockets187which are open towards the planar, front-facing thrust surface188of the orbital scroll member front face140, which superposes the rear-facing interior surface176of the housing26. These oil pockets187contain quantities of the substantially incompressible oil that lubricate the sliding interface between the orbital scroll member thrust surface188and the rear-facing thrust washer surface185. The thrust washer180may also be coated with a low friction material on at least its rear-facing surface185. Abutment between the front-facing thrust surface188of the orbital scroll member50, and the rear-facing surface185of the thrust washer180, limits forward axial movement of the orbital scroll member50away from the nonorbital scroll member52. The thrust washer180is also provided with circumferentially-distributed notches190in which the cylindrical members (e.g., the needle roller bearing assemblies178and/or the second pins172) are disposed.

Referring toFIG. 6, the thrust surface188of the orbital scroll member50is provided with an annular groove or oil distribution channel192located about the hub138. In the depicted embodiment, the groove192is circular, and centered about the hub axis134. In the depicted embodiment, the annular groove192is formed of a plurality of elongate arcuate grooves or groove segments192a,192b,192c, and192darranged in a circle, with their adjacent ends respectively interconnected through the first bores162a,162b,162c, and162d, as shown inFIGS. 6 and 9.

In the depicted embodiment, each arcuate groove segment192a-192dis of uniform width radially, and open at the thrust surface188. Each groove segment192a-192dmay also be of uniform depth from the planar thrust surface188. Alternatively, the groove segments192may have nonuniform width(s) and/or depth(s). At its juncture with a first bore162, the floor of each groove segment192a-192d, located between its radially spaced sides or edges, is preferably at the same distance or less from the thrust surface188than the rims165of the cups164are, as best shown inFIG. 8B. Thus, with the cups164and first pins166installed in the first and second bores162,168, the arcuate groove segments192a-192dare interconnected through the toroidal spaces170which accommodate the anti-rotation mechanism160.

Although groove192is shown as including separate, arcuate grooves or groove segments192a-192dintersecting the toroidal spaces170of the anti-rotation mechanism160, the oil distribution channel192may itself be continuous along its entire length as shown. Alternatively, the oil distribution channel192may be non-annular. Further, although the circular distribution channel192of the depicted embodiment is endless, it is envisioned that in certain embodiments, the channel192may extend between opposite terminal ends thereof that are not joined to each other directly indirectly in the orbital scroll member50, such as through an intermediate first bore162.

During compressor operation, compressed fluid at substantially discharge pressure and containing an entrained quantity of lubricating oil is expelled from the fluid pockets or compression chambers74of the compression mechanism76through the passageway or discharge aperture78in the nonorbital scroll member52, past discharge reed valve110, and into the discharge chamber102. The compressed working fluid/oil admixture flows from the discharge chamber102via a discharge chamber outlet or passage194located between the circumferential ends of the axially-stacked, C-shaped walls106and108that together define the continuous side wall of the discharge chamber102. These circumferential wall ends are indicated by points A and B inFIGS. 3-5. Points A and points B of the rear casing30and of the nonorbital scroll member52respectively coincide when these components are assembled together, thereby defining points A and B of the scroll compressor assembly discharge plenum44. The circumferentially elongate discharge chamber outlet194thus extends between discharge plenum points A and B. In other words, the discharge and exhaust chambers102and104are in fluid communication with each other through the passage194located between the discharge plenum points A and B.

In scroll compressor assembly22, the shaft rotation axis124lies in an imaginary plane196; the plane196is preferably positioned between discharge plenum points A and B. When operatively installed, compressor assemblies used in automotive refrigeration systems typically have a belt-driven drive shaft axis of rotation that extends in a generally horizontal direction; they are thus known as horizontal compressor assemblies. In its preferred mounting configuration and operating orientation, the shaft rotation axis124and the plane196of the scroll compressor assembly22are generally horizontal. In other words, the plane196of the operatively installed compressor assembly22is generally horizontal and preferably positioned between points A and B, within the passage194that extends between the discharge and exhaust chambers102,104, as can be understood with reference toFIG. 3. It can thus be understood that the scroll compressor assembly22is an embodiment of a horizontal scroll compressor assembly. Moreover, the discharge port40is preferably positioned vertically above the generally horizontal plane196when the compressor assembly22is in its operating orientation.

Oil sumps198and200are respectively located in the suction and discharge plenums42and44. The oil sump198located in the suction plenum42, and the oil sump200located in the discharge plenum44, are also referred to herein as the suction sump198and the discharge sump200, respectively. Normally, the respective oil surface levels202and204of these oil sumps are both located vertically below the plane196during compressor operation, as respectively indicated inFIGS. 9 and 3. Those of ordinary skill in the art will recognize that during compressor operation the oil deposited in the suction sump198is under substantially suction pressure, and the oil deposited in the discharge sump200is under relatively higher, substantially discharge pressure. They will also recognize that their respective oil surface levels202and204will vary with differing system operating conditions.

Oil separated from the working fluid as a result of the compressed admixture contacting compressor assembly surfaces in the discharge plenum44is collected in the discharge sump200. For example, with reference toFIGS. 3 and 4, the working fluid/oil admixture expelled from the discharge chamber102through the outlet or passage194will impact the interior side wall surface216of the housing26in the exhaust chamber104, causing a portion of the entrained oil to separate from the working fluid and collect on the side wall surface216. Oil collected on the interior side wall surface216flows downwardly therealong, primarily under the force of gravity, and is received into the region of the exhaust chamber104containing the discharge sump200.

Lubricating oil collected in the discharge sump200, which is under substantially discharge pressure, is conveyed from the discharge sump200to the suction plenum42, within the compressor housing26, through an oil return conduit218. The discharge plenum44and the suction plenum42are in fluid communication internally of the scroll compressor assembly22through the oil return conduit218. During compressor operation, oil flow through the oil return conduit218is continuous, but restricted by a length and/or a cross-sectional size of the conduit218. The oil flow through the oil return conduit218is urged by the pressure differential between the suction and discharge plenums42and44, i.e., between substantially discharge and substantially suction pressures.

The oil return conduit218has an inlet220opening into the discharge sump200at a location normally below the surface level204of the oil pooled therein. The oil return conduit218has a first leg or first portion222that extends from the conduit inlet220to the entrance224of an oil return bore226. The oil return bore226extends axially through the nonorbital scroll member52, as best seen inFIG. 5.

The first leg222of the oil return conduit218may be defined by a groove222formed in one or the other, or both, of a pair of the axially abutting surfaces90,92of bosses projecting from the rear face86of the nonorbital scroll member52and the interfacing interior surface88of the rear casing30. Alternatively, the first leg222of the oil return conduit218may be defined by an elongate slot extending through the axial thickness of a gasket (not shown) sandwiched between that pair of axially abutting boss surfaces90,92. Alternatively, the first leg222may be defined by one or a plurality of intersecting bores (not shown) extending through one of these abutting bosses. In the depicted embodiment, a first leg-defining groove222is formed in portions of the axial abutment surface92of a boss projecting from the interior, front-facing surface88of the rear casing30, as shown inFIGS. 3 and 4.

The oil return bore226extending through nonorbital scroll member52defines a second leg or second portion228of the oil return conduit218that has a minimal cross-sectional size larger than that of the conduit first leg222. The terminal end230of the first leg groove222, shown inFIG. 3, is located within an area bounded by the circumference of the oil return bore entrance224. Referring toFIGS. 3 and 5, the entrance224to the oil return bore226is located in a portion232(FIG. 5) of the abutment surface90of the nonorbital scroll member52, and that surface portion232is superposed by a portion234(FIG. 3) of the abutment surface92of the rear casing30in which the terminal end230of the conduit first leg groove222is located. Thus, the first and second legs222,228of the oil return conduit218are in fluid communication with each other, and the oil return conduit218is sealed along its overall length from the discharge plenum44.

Referring toFIG. 9, the exit236of the oil return bore226, which is located axially opposite its entrance224, is open to the suction plenum42at a location normally above the oil surface level202of the suction sump198. During compressor operation, oil received into the suction plenum42via the oil return conduit218tends to flow under the influence of gravity toward the suction sump198, in which it is received and held at substantially suction pressure.

Oil which is not separated from the compressed working fluid in the discharge plenum44exits the compressor assembly22through the discharge port40as part of the working fluid/oil admixture at a discharge pressure, and is directed to the remainder of the refrigerant system. Normally, portions of the oil carried in the admixture discharged from the compressor assembly22are separated and remixed with the working fluid in the refrigerant system, at locations upstream of the compressor assembly22. Eventually, oil discharged from the compressor assembly22in a compressed working fluid/oil admixture returns to the compressor assembly entrained in working fluid received at a suction pressure through suction port38.

Within the suction plenum42, oil in the admixture received via the suction port38may also separate from the working fluid as a result of the admixture contacting surfaces within the suction plenum, and be received into the suction sump198. A portion of the entrained oil received into the suction plenum42via the suction port38, or oil returned to the suction plenum42via the oil return conduit218and remixed with working fluid at substantially suction pressure, is drawn into the inlet of the compression mechanism76and discharged via the passageway78into the discharge plenum44.

Oil disposed in the suction sump198that does not become admixed with working fluid in the suction plenum42is partly distributed within the suction plenum42. This oil may be distributed by being sloshed, or splashed or carried or pumped by movement of the orbital scroll member50in its circular orbit about the shaft rotation axis124. The distributed oil becomes deposited on surfaces in the suction plenum42, in the oil pockets187, and between the thrust surface188and the interfacing surface185of the thrust washer180.

The oil distribution channel192better ensures that oil is distributed between the thrust surface188and the thrust washer180, and replenished to the oil pockets187. The oil introduced to the distribution channel192from the suction sump198and/or the space170in lowermost first bore162ais urged therealong under the influence of pumping action, and urged outwardly of the groove192into the pockets187and between the thrust surface188and the thrust washer surface185. A lower portion of the groove192receives from the suction sump198oil that is distributed by the oil distribution channel192. Referring toFIG. 9, in the depicted embodiment, the ends of the groove segments192aand192dopen into the toroidal space defining the circular track170within the first bore162a. At least a portion of the toroidal space170is located within the suction sump198. The orbital movement of the lowermost circular track170about its shown needle bearing assembly178tends to force oil received from the suction sump198into the toroidal space170within first bore162a, into at least one of the groove segments192aand192d, thereby urging oil received into the oil distribution channel192along the oil distribution channel. Under certain operating conditions, oil may be forced from this lowermost toroidal space170into only one of the groove segments192aand192d, whereby the oil received into the oil distribution channel192is urged to flow in a single direction therealong. Under other operating conditions, oil may be forced from the lowermost space170into both of the groove segments192aand192d, whereby the oil received into the oil distribution channel192is urged to flow in opposite directions therealong. Additionally, the lower portions of groove segments192aand/or192dmay, under some operating conditions, extend below the suction sump oil surface level202and thus become open to receive oil from the suction sump198directly therein, rather than receive it solely from the lowermost toroidal space170.

Whether oil from the suction sump198is urged to flow to the upper reaches of the oil distribution channel192via one or both of the groove segments192aand192dduring compressor operation is thought to depend in part on the depth of the oil in the suction sump198. An oil surface level202high enough to immerse most of the cylindrical member, e.g., depicted needle bearing assembly178, is expected to facilitate the pumping of oil received by the space170within the first bore162afrom the suction sump198along both of the groove segments192aand192d; whereas an oil surface level oil high enough to immerse only a minor portion of the cylindrical member is expected to facilitate the pumping of the oil primarily into and along only one of the groove segments192aand192d, in which case oil will be urged along a path defined by the serially arranged groove segments192a-192dthat define the oil distribution channel192.

It can thus be understood that oil is delivered to the interface between the orbital scroll member thrust surface188and the thrust washer surface185, at locations between the axially superposed orbital scroll member front face140and housing rear-facing interior surface176, and the delivered oil lubricates the interfacing surfaces188,185and replenishes the oil pockets187. Moreover, during compressor operation, pressure in the oil being delivered to locations between the axially superposed surfaces176and188via the distribution channel192is built up, in part due to oil flow resistances through the groove segments192a-192d, and along the interface between the slightly axially spaced thrust washer surface185and thrust surface188. This increase in pressure of the delivered oil induces hydrodynamic forces that act to separate the interfacing surfaces185and188, and support the orbital scroll member50axially away from the thrust washer180and the rear-facing surface176of the front casing28. As the oil which lubricates and separates surfaces185and188leaks from between their interface, it is recollected in the suction sump198.

The foregoing description of the best mode for carrying out the invention is considered as illustrative of principles of the invention. It will be understood by those of ordinary skill in the art that modifications to the described embodiment can be made that are within the scope of the invention.

As to a further discussion of the manner of usage and operation of the present invention, the same should be apparent from the above description. With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to those of ordinary skill in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.