Scroll compressor with captured thrust washer

A load transmittal apparatus transfers an axial load to a thrust surface during operation of a scroll compressor.

FIELD OF THE INVENTION

The present invention generally relates to scroll compressors for compressing refrigerant and more particularly to a load transmittal apparatus for transferring an axial load to a thrust surface during operation of the scroll compressor.

BACKGROUND OF THE INVENTION

A scroll compressor is a certain type of compressor that is used to compress refrigerant for such applications as refrigeration, air conditioning, industrial cooling and freezer applications, and/or other applications where compressed fluid may be used. Such prior scroll compressors are known, for example, as exemplified in U.S. Pat. No. 6,398,530 to Hasemann; U.S. Pat. No. 6,814,551, to Kammhoff et al.; U.S. Pat. No. 6,960,070 to Kammhoff et al.; and U.S. Pat. No. 7,112,046 to Kammhoff et al., all of which are assigned to a Bitzer entity closely related to the present assignee. As the present disclosure pertains to improvements that can be implemented in these or other scroll compressor designs, the entire disclosures of U.S. Pat. Nos. 6,398,530; 7,112,046; 6,814,551; and 6,960,070 are hereby incorporated by reference in their entireties.

As is exemplified by these patents, scroll compressors assemblies conventionally include an outer housing having a scroll compressor contained therein. A scroll compressor includes first and second scroll compressor members. A first compressor member is typically arranged stationary and fixed in the outer housing. A second scroll compressor member is movable relative to the first scroll compressor member in order to compress refrigerant between respective scroll ribs which rise above the respective bases and engage in one another. Conventionally the movable scroll compressor member is driven about an orbital path about a central axis for the purposes of compressing refrigerant. An appropriate drive unit, typically an electric motor, is provided usually within the same housing to drive the movable scroll member.

In some scroll compressors, it is known to have axial restraint, whereby the fixed scroll member has a limited range of movement. This can be desirable due to thermal expansion when the temperature of the orbiting scroll and fixed scroll increases causing these components to expand. Examples of an apparatus to control such restraint are shown in U.S. Pat. No. 5,407,335, issued to Caillat et al., the entire disclosure of which is hereby incorporated by reference.

In a scroll compressor, there is typically some amount of load that is induced in the axial direction of the crankshaft. For a vertical scroll compressor, this load is a combination of the mass of the rotating components as well as any electrically induced load caused by intentional or unintentional axial misalignment of the motor stator and motor rotor. These loads are commonly transmitted between the rotating crankshaft and a stationary housing a thrust surface. The thrust surface may be designed into the stationary component but such surface tends to wear away and surface preparation must be given careful consideration which adds costs to the compressor. It is also known to use a thrust washer, but to prevent unwanted movement, such thrust washer is fixed in place with various ways including the use of fastener(s), adhesive or tabs formed into the circumference of the washer. Such methods add cost to the compressor.

The present disclosure is directed towards improvements over the state of the art as it relates to the above-described features and other features of scroll compressors.

BRIEF SUMMARY OF THE INVENTION

There is provided a scroll compressor including a load transfer apparatus. The scroll compressor includes a rotating shaft and a stationary lower bearing member. The load transfer apparatus includes a central cylindrical hub defined by the stationary lower bearing member, with the central hub further defining an opening. A cylindrical bearing is configured to seat in the opening. The cylindrical bearing is configured to receive one end of the rotating shaft of the scroll compressor. A thrust washer is disposed in the opening of the central hub and captured axially within the lower bearing member by the cylindrical bearing. An axial load along the center line of the shaft transmits to the stationary lower bearing member through the thrust washer.

A load transfer apparatus of the present disclosure captures the thrust washer in the opening without the use of a fastener or an adhesive. The thrust washer is configured with a smooth circumference, meaning there are no tabs or notches on the circumference of the thrust washer. In one embodiment the thrust washer is metal and in another embodiment the thrust washer is composed of a matrix of a metal, for example steel, bronze, and aluminum, and a polymeric layer, for example PTFE, glass fibers, graphite fibers, silica, molybdenum disulfide or combinations of such material. The cylindrical bearing can also be composed of a metal, and a matrix of metal and a polymeric layer as described above.

There is further provided a scroll compressor including a housing having an upper end and a lower end. A pair of scroll compressor bodies are disposed in the housing. The scroll bodies include a first scroll body and a second scroll body, with the first and second scroll bodies having respective bases and respective scroll ribs that project from the respective bases. The scroll ribs mutually engage each other with the second scroll body being moveable relative to the first scroll body for a compressing fluid.

A pilot ring engages a perimeter surface of the first scroll body to limit movement of the first scroll body in the radial direction. The first scroll body has a first radially-outward-projecting limit tab being configured to limit movement of the first scroll body and at least one of the axial and rotational directions.

A stationary lower bearing member is disposed proximate the lower end of the housing. A motor is disposed in the housing, with the motor including a stator and a rotor with the rotor coupled to a shaft configured to rotate within the housing and with the pair of scroll compressor bodies coupled to the shaft.

A load transfer apparatus includes a central cylindrical hub defined by its stationary lower bearing member with the central hub defining an opening. A cylindrical bearing is configured to seat in the opening, with the cylindrical bearing further configured to receive one end of the shaft. A thrust washer is disposed in the opening of the central hub and captured axially within the lower bearing member by the cylindrical bearing. An axial load along the center line of the shaft is transmitted to the stationary lower bearing member through the thrust washer.

In another embodiment, the pilot ring is formed separately from a crankshaft case, with the pilot ring being attached to a crankcase via a plurality of posts extending axially therebetween. The first and second scroll bodies are disposed within the attached pilot ring and crankcase. A key coupling that acts upon the second scroll body, is disposed within the attached pilot ring and crankcase. The key coupling extends into spaces between adjacent posts, and the spaces allow the pilot ring, crankcase, and key coupling to have outer diameters that are approximately equal to the inner diameter of the housing.

In another aspect, embodiments of the scroll compressor provide a method of transferring axial loading from a rotating shaft in the scroll compressor to a stationary lower bearing member of the scroll compressor. An axial load on the rotating shaft typically includes the mass of the shaft, a motor rotor, and counter weights of the scroll compressor plus electrical-induced loads caused by misalignment of the motor rotor and a motor stator. The method includes depositing a thrust washer at the bottom of an opening in a central cylindrical hub defined by the stationary load bearing member. A cylindrical bearing is inserted into the opening in the central cylindrical hub. The cylindrical bearing is pressed into the opening axially until the bearing captures the thrust washer into position axially in the opening. An end of the shaft is inserted into the cylindrical bearing in the opening defined in the central cylindrical hub, wherein the axial load on the shaft around the center line of the shaft is transmitted to the stationary load bearing member through the thrust washer.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention is illustrated in the figures as a scroll compressor assembly10generally including an outer housing12in which a scroll compressor14can be driven by a drive unit16. The scroll compressor assembly10may be arranged in a refrigerant circuit for refrigeration, industrial cooling, freezing, air conditioning or other appropriate applications where compressed fluid is desired. Appropriate connection ports provide for connection to a refrigeration circuit and include a refrigerant inlet port18and a refrigerant outlet port20extending through the outer housing12. The scroll compressor assembly10is operable through operation of the drive unit16to operate the scroll compressor14and thereby compress an appropriate refrigerant or other fluid that enters the refrigerant inlet port18and exits the refrigerant outlet port20in a compressed high-pressure state.

The outer housing for the scroll compressor assembly10may take many forms. In particular embodiments of the invention, the outer housing12includes multiple shell sections. In the embodiment ofFIG. 1, the outer housing12includes a central cylindrical housing section24, and a top end housing section26, and a single-piece bottom shell28that serves as a mounting base. In certain embodiments, the housing sections24,26,28are formed of appropriate sheet steel and welded together to make a permanent outer housing12enclosure. However, if disassembly of the housing is desired, other housing assembly provisions can be made that can include metal castings or machined components, wherein the housing sections24,26,28are attached using fasteners.

As can be seen in the embodiment ofFIG. 1, the central housing section24is cylindrical, joined with the top end housing section26. In this embodiment, a separator plate30is disposed in the top end housing section26. During assembly, these components can be assembled such that when the top end housing section26is joined to the central cylindrical housing section24, a single weld around the circumference of the outer housing12joins the top end housing section26, the separator plate30, and the central cylindrical housing section24. In particular embodiments, the central cylindrical housing section24is welded to the single-piece bottom shell28, though, as stated above, alternate embodiments would include other methods of joining (e.g., fasteners) these sections of the outer housing12. Assembly of the outer housing12results in the formation of an enclosed chamber31that surrounds the drive unit16, and partially surrounds the scroll compressor14. In particular embodiments, the top end housing section26is generally dome-shaped and includes a respective cylindrical side wall region32that abuts the top of the central cylindrical housing section24, and provides for closing off the top end of the outer housing12. As can also be seen fromFIG. 1, the bottom of the central cylindrical housing section24abuts a flat portion just to the outside of a raised annular rib34of the bottom end housing section28. In at least one embodiment of the invention, the central cylindrical housing section24and bottom end housing section28are joined by an exterior weld around the circumference of a bottom end of the outer housing12.

In a particular embodiment, the drive unit16in is the form of an electrical motor assembly40. The electrical motor assembly40operably rotates and drives a shaft46. Further, the electrical motor assembly40generally includes a stator50comprising electrical coils and a rotor52that is coupled to the drive shaft46for rotation together. The stator50is supported by the outer housing12, either directly or via an adapter. The stator50may be press-fit directly into outer housing12, or may be fitted with an adapter (not shown) and press-fit into the outer housing12. In a particular embodiment, the rotor52is mounted on the drive shaft46, which is supported by upper and lower bearings42,44. Energizing the stator50is operative to rotatably drive the rotor52and thereby rotate the drive shaft46about a central axis54. Applicant notes that when the terms “axial” and “radial” are used herein to describe features of components or assemblies, they are defined with respect to the central axis54. Specifically, the term “axial” or “axially-extending” refers to a feature that projects or extends in a direction parallel to the central axis54, while the terms “radial’ or “radially-extending” indicates a feature that projects or extends in a direction perpendicular to the central axis54.

In one embodiment an axial load induced along the centerline54of the crankshaft46is transferred to the stationary lower bearing member44by a load transfer apparatus65.

Referring toFIGS. 15-17, an exemplary embodiment of a load transfer apparatus65is illustrated in an assembled view and an exploded view. A central cylindrical hub58is defined in the lower bearing member44, with the cylindrical hub58further defining an opening59. The opening is configured to receive one end49of the shaft46and a cylindrical bearing60. The bearing60is lubricated by oil through an orifice81defined in the shaft46. The orifice81is in fluid communication with the internal lubricant passageway80defined by the shaft46.

A thrust washer55is disposed in the opening59at the bottom of the central cylindrical hub58(SeeFIG. 16). The thrust washer55is disposed between the cylindrical bearing60and the stationary lower bearing44. In one configuration the thrust washer55is captured in the opening59by the cylindrical bearing60. During compressor14operation, since the friction between the shaft46and thrust washer55is substantially less than the friction between the thrust washer55at the bearing housing44the thrust washer55will remain stationary, i.e. will not spin with the shaft46or move axially. In another configuration the cylindrical bearing60is pressed into the opening59axially until sufficient force is exerted against the thrust washer55to capture the thrust washer in position axially but allow the thrust washer55to rotate since there is some axial clearance between the cylindrical bearing and the washer. With the load transfer apparatus65, there is no need to fix the thrust washer55in position with adhesive, fasteners or other means, for example tabs defined on the circumference of the thrust washer55. The thrust washer55in the described load transfer apparatus65is configured with a smooth circumference, i.e. no tabs, grooves or projections. The thrust washer55is composed of one of a metal or a metal and a polymeric layer capable of transferring the axial load from the shaft46to the lower bearing44.

The two bearings, cylindrical60or thrust washer55, can be either all metal or a metal-nonmetal assemblage. In a typical configuration, either or both bearings are composed of three layers. The outermost (away from the load bearing surface) is steel (to provide structural strength. To this is bonded a layer of sintered bronze particles in a “loose” (i.e. porous) matrix. Finally a polymeric layer is bonded into the porous matrix. The polymeric layer may also include PTFE, glass fibers or particles, graphite fibers or particles, silica, molybdenum disulfide, and/or other fillers. Alternately, all-metal bearings will typically have the steel shell and a solid bronze or babbitt liner. Some others may have a steel shell and porous bronze liner with a polymer or PTFE filing the bronze matrix but not forming an actual layer on top of the bronze. Another configuration is a bearing made of a single metal, without the described layered construction. In this case the material is typically a bronze or aluminum alloy.

The axial load is typically the combination of the mass of the rotating components that include the shaft46, the motor rotor52and counter weight and other members coupled to the shaft46. The axial load also includes any electrical induced load caused by intentional or unintentional axial misalignment of the motor stator50and motor rotor52.

With reference toFIG. 1, the lower bearing member44includes a central, generally cylindrical hub58that includes a central bushing58and opening59to provide the cylindrical bearing60to which the drive shaft46is journaled for rotational support. A plate-like ledge region68of the lower bearing member44projects radially outward from the central hub58, and serves to separate a lower portion of the stator50from an oil lubricant sump76. An axially-extending perimeter surface70of the lower bearing member44may engage with the inner diameter surface of the central housing section24to centrally locate the lower bearing member44and thereby maintain its position relative to the central axis54. This can be by way of an interference and press-fit support arrangement between the lower bearing member44and the outer housing12.

In the embodiment ofFIG. 1, the drive shaft46has an impeller tube47attached at the bottom end of the drive shaft46. In a particular embodiment, the impeller tube47is of a smaller diameter than the drive shaft46, and is aligned concentrically with the central axis54. As can be seen fromFIG. 1, the drive shaft46and impeller tube47pass through an opening in the cylindrical hub58of the lower bearing member44. At its upper end, the drive shaft46is journaled for rotation within the upper bearing member42. Upper bearing member42may also be referred to as a “crankcase.”

The drive shaft46further includes an offset eccentric drive section74that has a cylindrical drive surface75(shown inFIG. 2) about an offset axis that is offset relative to the central axis54. This offset drive section74is journaled within a cavity of a movable scroll compressor body112of the scroll compressor14to drive the movable scroll compressor body112about an orbital path when the drive shaft46rotates about the central axis54. To provide for lubrication of all of the various bearing surfaces, the outer housing12provides the oil lubricant sump76at the bottom end of the outer housing12in which suitable oil lubricant is provided. The impeller tube47has an oil lubricant passage and inlet port78formed at the end of the impeller tube47. Together, the impeller tube47and inlet port78act as an oil pump when the drive shaft46is rotated, and thereby pumps oil out of the lubricant sump76into an internal lubricant passageway80defined within the drive shaft46. During rotation of the drive shaft46, centrifugal force acts to drive lubricant oil up through the lubricant passageway80against the action of gravity. The lubricant passageway80has various radial passages projecting therefrom to feed oil through centrifugal force to appropriate bearing surfaces and thereby lubricate sliding surfaces as may be desired.

As shown inFIGS. 2 and 3, the upper bearing member, or crankcase,42includes a central bearing hub87into which the drive shaft46is journaled for rotation, and a thrust bearing84that supports the movable scroll compressor body112. (See alsoFIG. 9). Extending outward from the central bearing hub87is a disk-like portion86that terminates in an intermittent perimeter support surface88defined by discretely spaced posts89. In the embodiment ofFIG. 3, the central bearing hub87extends below the disk-like portion86, while the thrust bearing84extends above the disk-like portion86. In certain embodiments, the intermittent perimeter support surface88is adapted to have an interference and press-fit with the outer housing12. In the embodiment ofFIG. 3, the crankcase42includes four posts89, each post having an opening91configured to receive a threaded fastener. It is understood that alternate embodiments of the invention may include a crankcase with more or less than four posts, or the posts may be separate components altogether. Alternate embodiments of the invention also include those in which the posts are integral with the pilot ring instead of the crankcase.

In certain embodiments such as the one shown inFIG. 3, each post89has an arcuate outer surface93spaced radially inward from the inner surface of the outer housing12, angled interior surfaces95, and a generally flat top surface97which can support a pilot ring160. In this embodiment, intermittent perimeter support surface88abuts the inner surface of the outer housing12. Further, each post89has a chamfered edge94on a top, outer portion of the post89. In particular embodiments, the crankcase42includes a plurality of spaces244between adjacent posts89. In the embodiment shown, these spaces244are generally concave and the portion of the crankcase42bounded by these spaces244will not contact the inner surface of the outer housing12.

The upper bearing member or crankcase42also provides axial thrust support to the movable scroll compressor body112through a bearing support via an axial thrust surface96of the thrust bearing84. While, as shownFIGS. 1-3, the crankcase42may be integrally provided by a single unitary component,FIGS. 13 and 14show an alternate embodiment in which the axial thrust support is provided by a separate collar member198that is assembled and concentrically located within the upper portion of the upper bearing member199along stepped annular interface100. The collar member198defines a central opening102that is a size large enough to clear a cylindrical bushing drive hub128of the movable scroll compressor body112in addition to the eccentric offset drive section74, and allow for orbital eccentric movement thereof.

Turning in greater detail to the scroll compressor14, the scroll compressor includes first and second scroll compressor bodies which preferably include a stationary fixed scroll compressor body110and a movable scroll compressor body112. While the term “fixed” generally means stationary or immovable in the context of this application, more specifically “fixed” refers to the non-orbiting, non-driven scroll member, as it is acknowledged that some limited range of axial, radial, and rotational movement is possible due to thermal expansion and/or design tolerances.

The movable scroll compressor body112is arranged for orbital movement relative to the fixed scroll compressor body110for the purpose of compressing refrigerant. The fixed scroll compressor body includes a first rib114projecting axially from a plate-like base116and is designed in the form of a spiral. Similarly, the movable scroll compressor body112includes a second scroll rib118projecting axially from a plate-like base120and is in the shape of a similar spiral. The scroll ribs114,118engage in one another and abut sealingly on the respective surfaces of bases120,116of the respectively other compressor body112,110. As a result, multiple compression chambers122are formed between the scroll ribs114,118and the bases120,116of the compressor bodies112,110. Within the chambers122, progressive compression of refrigerant takes place. Refrigerant flows with an initial low pressure via an intake area124surrounding the scroll ribs114,118in the outer radial region (see e.g.FIGS. 1-2). Following the progressive compression in the chambers122(as the chambers progressively are defined radially inward), the refrigerant exits via a compression outlet126which is defined centrally within the base116of the fixed scroll compressor body110. Refrigerant that has been compressed to a high pressure can exit the chambers122via the compression outlet126during operation of the scroll compressor14.

The movable scroll compressor body112engages the eccentric offset drive section74of the drive shaft46. More specifically, the receiving portion of the movable scroll compressor body112includes the cylindrical bushing drive hub128which slideably receives the eccentric offset drive section74with a slideable bearing surface provided therein. In detail, the eccentric offset drive section74engages the cylindrical bushing drive hub128in order to move the movable scroll compressor body112about an orbital path about the central axis54during rotation of the drive shaft46about the central axis54. Considering that this offset relationship causes a weight imbalance relative to the central axis54, the assembly typically includes a counterweight130that is mounted at a fixed angular orientation to the drive shaft46. The counterweight130acts to offset the weight imbalance caused by the eccentric offset drive section74and the movable scroll compressor body112that is driven about an orbital path. The counterweight130includes an attachment collar132and an offset weight region134(see counterweight130shown best inFIGS. 2 and 3) that provides for the counterweight effect and thereby balancing of the overall weight of the components rotating about the central axis54. This provides for reduced vibration and noise of the overall assembly by internally balancing or cancelling out inertial forces.

With reference toFIGS. 4 and 7, the guiding movement of the scroll compressor14can be seen. To guide the orbital movement of the movable scroll compressor body112relative to the fixed scroll compressor body110, an appropriate key coupling140may be provided. Keyed couplings140are often referred to in the scroll compressor art as an “Oldham Coupling.” In this embodiment, the key coupling140includes an outer ring body142and includes two axially-projecting first keys144that are linearly spaced along a first lateral axis146and that slide closely and linearly within two respective keyway tracks or slots115(shown inFIGS. 1 and 2) of the fixed scroll compressor body110that are linearly spaced and aligned along the first axis146as well. The slots115are defined by the stationary fixed scroll compressor body110such that the linear movement of the key coupling140along the first lateral axis146is a linear movement relative to the outer housing12and perpendicular to the central axis54. The keys can comprise slots, grooves or, as shown, projections which project axially (i.e., parallel to central axis54) from the ring body142of the key coupling140. This control of movement along the first lateral axis146guides part of the overall orbital path of the movable scroll compressor body112.

Referring specifically toFIG. 4, the key coupling140includes four axially-projecting second keys152in which opposed pairs of the second keys152are linearly aligned substantially parallel relative to a second transverse lateral axis154that is perpendicular to the first lateral axis146. There are two sets of the second keys152that act cooperatively to receive projecting sliding guide portions254that project from the base120on opposite sides of the movable scroll compressor body112. The guide portions254linearly engage and are guided for linear movement along the second transverse lateral axis by virtue of sliding linear guiding movement of the guide portions254along sets of the second keys152.

It can be seen inFIG. 4that four sliding contact surfaces258are provided on the four axially-projecting second keys152of the key coupling140. As shown, each of the sliding contact surfaces258is contained in its own separate quadrant252(the quadrants252being defined by the mutually perpendicular lateral axes146,154). As shown, cooperating pairs of the sliding contact surfaces258are provided on each side of the first lateral axis146.

By virtue of the key coupling140, the movable scroll compressor body112has movement restrained relative to the fixed scroll compressor body110along the first lateral axis146and second transverse lateral axis154. This results in the prevention of relative rotation of the movable scroll body as it allows only translational motion. More particularly, the fixed scroll compressor body110limits motion of the key coupling140to linear movement along the first lateral axis146; and in turn, the key coupling140when moving along the first lateral axis146carries the movable scroll112along the first lateral axis146therewith. Additionally, the movable scroll compressor body can independently move relative to the key coupling140along the second transverse lateral axis154by virtue of relative sliding movement afforded by the guide portions254which are received and slide between the second keys152. By allowing for simultaneous movement in two mutually perpendicular axes146,154, the eccentric motion that is afforded by the eccentric offset drive section74of the drive shaft46upon the cylindrical bushing drive hub128of the movable scroll compressor body112is translated into an orbital path movement of the movable scroll compressor body112relative to the fixed scroll compressor body110.

To carry axial thrust loads, the movable scroll compressor body112also includes flange portions268projecting in a direction perpendicular relative to the guiding flange portions262(e.g. along the first lateral axis146). These additional flange portions268are preferably contained within the diametrical boundary created by the guide flange portions262so as to best realize the size reduction benefits. Yet a further advantage of this design is that the sliding faces254of the movable scroll compressor body112are open and not contained within a slot. This is advantageous during manufacture in that it affords subsequent machining operations such as finishing milling for creating the desirable tolerances and running clearances as may be desired.

Generally, scroll compressors with movable and fixed scroll compressor bodies require some type of restraint for the fixed scroll compressor body110which restricts the radial movement and rotational movement but which allows some degree of axial movement so that the fixed and movable scroll compressor bodies110,112are not damaged during operation of the scroll compressor14. In embodiments of the invention, that restraint is provided by a pilot ring160, as shown inFIGS. 5-9.FIG. 5shows the top side of pilot ring160, constructed in accordance with an embodiment of the invention. The pilot ring160has a top surface167, a cylindrical outer perimeter surface178, and a cylindrical first inner wall169. The pilot ring160ofFIG. 5includes four holes161through which fasteners, such as threaded bolts, may be inserted to allow for attachment of the pilot ring160to the crankcase42. In a particular embodiment, the pilot ring160has axially-raised portions171(also referred to as mounting bosses) where the holes161are located. One of skill in the art will recognize that alternate embodiments of the pilot ring may have greater or fewer than four holes for fasteners. The pilot ring160may be a machined metal casting, or, in alternate embodiments, a machined component of iron, steel, aluminum, or some other similarly suitable material.

FIG. 6shows a bottom view of the pilot ring160showing the four holes161along with two slots162formed into the pilot ring160. In the embodiment ofFIG. 6, the slots162are spaced approximately 180 degrees apart on the pilot ring160. Each slot162is bounded on two sides by axially-extending side walls193. As shown inFIG. 6, the bottom side of the pilot ring160includes a base portion163which is continuous around the entire circumference of the pilot ring160forming a complete cylinder. But on each side of the two slots162, there is a semi-circular stepped portion164which covers some of the base portion163such that a ledge165is formed on the part of the pilot ring160radially inward of each semi-circular stepped portion164. The inner-most diameter or the ledge165is bounded by the first inner wall169.

A second inner wall189runs along the inner diameter of each semi-circular stepped portion164. Each semi-circular stepped portion164further includes a bottom surface191, a notched section166, and a chamfered lip190. In the embodiment ofFIG. 6, each chamfered lip190runs the entire length of the semi-circular stepped portion164making the chamfered lip190semi-circular as well. Each chamfered lip190is located on the radially-outermost edge of the bottom surface191, and extends axially from the bottom surface191. Further, each chamfered lip190includes a chamfered edge surface192on an inner radius of the chamfered lip190. When assembled, the chamfered edge surface192is configured to mate with the chamfered edge94on each post89of the crankcase. The mating of these chamfered surfaces allows for an easier, better-fitting assembly, and reduces the likelihood of assembly problems due to manufacturing tolerances.

In the embodiment ofFIG. 6, the notched sections166are approximately 180 degrees apart on the pilot ring160, and each is about midway between the two ends of the semi-circular stepped portion164. The notched sections166are bounded on the sides by sidewall sections197. Notched sections166thus extend radially and axially into the semi-circular stepped portion164of the pilot ring160.

FIG. 7shows an exploded view of the scroll compressor14assembly, according to an embodiment of the invention. The top-most component shown is the pilot ring160which is adapted to fit over the top of the fixed scroll compressor body110. The fixed scroll compressor body110has a pair of first radially-outward projecting limit tabs111. In the embodiment ofFIG. 7, one of the pair of first radially-outward projecting limit tabs111is attached to an outermost perimeter surface117of the first scroll rib114, while the other of the pair of first radially-outward projecting limit tabs111is attached to a perimeter portion of the fixed scroll compressor body110below a perimeter surface119. In further embodiments, the pair of first radially-outward projecting limit tabs111are spaced approximately 180 degrees apart. Additionally, in particular embodiments, each of the pair of first radially-outward-projecting limit tabs111has a slot115therein. In particular embodiments, the slot115may be a U-shaped opening, a rectangular-shaped opening, or have some other suitable shape.

The fixed scroll compressor body110also has a pair of second radially-outward projecting limit tabs113, which, in this embodiment, are spaced approximately 180 degrees apart. In certain embodiments, the second radially-outward projecting limit tabs113share a common plane with the first radially-outward-projecting limit tabs111. Additionally, in the embodiment ofFIG. 7, one of the pair of second radially-outward projecting limit tabs113is attached to an outermost perimeter surface117of the first scroll rib114, while the other of the pair of second radially-outward projecting limit tabs113is attached to a perimeter portion of the fixed scroll compressor body110below the perimeter surface119. The movable scroll compressor body112is configured to be held within the keys of the key coupling140and mates with the fixed scroll compressor body110. As explained above, the key coupling140has two axially-projecting first keys144, which are configured to be received within the slots115in the first radially-outward-projecting limit tabs111. When assembled, the key coupling140, fixed and movable scroll compressor bodies110,112are all configured to be disposed within crankcase42, which can be attached the to the pilot ring160by the threaded bolts168shown above the pilot ring160.

Referring still toFIG. 7, the fixed scroll compressor body110includes plate-like base116(seeFIG. 14) and a perimeter surface119spaced axially from the plate-like base116. In a particular embodiment, the entirety of the perimeter surface119surrounds the first scroll rib114of the fixed scroll compressor body110, and is configured to abut the first inner wall169of the pilot ring160, though embodiments are contemplated in which the engagement of the pilot ring and fixed scroll compressor body involve less than the entire circumference. In particular embodiments of the invention, the first inner wall169is precisely toleranced to fit snugly around the perimeter surface119to thereby limit radial movement of the first scroll compressor body110, and thus provide radial restraint for the first scroll compressor body110. The plate-like base116further includes a radially-extending top surface121that extends radially inward from the perimeter surface119. The radially-extending top surface121extends radially inward towards a step-shaped portion123(seeFIG. 8). From this step-shaped portion123, a cylindrical inner hub region172and peripheral rim174extend axially (i.e., parallel to central axis54, when assembled into scroll compressor assembly10).

FIG. 8shows the components ofFIG. 7fully assembled. The pilot ring160securely holds the fixed scroll compressor body110in place with respect to the movable scroll compressor body112and key coupling140. The threaded bolts168attach the pilot ring160and crankcase42. As can be seen fromFIG. 8, each of the pair of first radially-outward projecting limit tabs111is positioned in its respective slot162of the pilot ring160. As stated above, the slots115in the pair of first radially-outward projecting limit tabs111are configured to receive the two axially-projecting first keys144. In this manner, the pair of first radially-outward projecting limit tabs111engage the side portion193of the pilot ring slots162to prevent rotation of the fixed scroll compressor body110, while the key coupling first keys144engage a side portion of the slot115to prevent rotations of the key coupling140. Limit tabs111also provide additional (to limit tabs113) axial limit stops.

Though not visible in the view ofFIG. 8, each of the pair of second radially-outward projecting limit tabs113(seeFIG. 7) is nested in its respective notched section166of the pilot ring160to constrain axial movement of the fixed scroll compressor body110thereby defining a limit to the available range of axial movement of the fixed scroll compressor body110. The pilot ring notched sections166are configured to provide some clearance between the pilot ring160and the pair of second radially-outward projecting limit tabs113to provide for axial restraint between the fixed and movable scroll compressor bodies110,112during scroll compressor operation. However, the radially-outward projecting limit tabs113and notched sections166also keep the extent of axial movement of the fixed scroll compressor body110to within an acceptable range.

It should be noted that “limit tab” is used generically to refer to either or both of the radially-outward projecting limit tabs111,113. Embodiments of the invention may include just one of the pairs of the radially-outward projecting limit tabs, or possibly just one radially-outward projecting limit tab, and particular claims herein may encompass these various alternative embodiments

As illustrated inFIG. 8, the crankcase42and pilot ring160design allow for the key coupling140, and the fixed and movable scroll compressor bodies110,112to be of a diameter that is approximately equal to that of the crankcase42and pilot ring160. As shown inFIG. 1, the diameters of these components may abut or nearly abut the inner surface of the outer housing12, and, as such, the diameters of these components are approximately equal to the inner diameter of the outer housing12. It is also evident that when the key coupling140is as large as the surrounding compressor outer housing12allows, this in turn provides more room inside the key coupling140for a larger thrust bearing which in turn allows a larger scroll set. This maximizes the scroll compressor14displacement available within a given diameter outer housing12, and thus uses less material at less cost than in conventional scroll compressor designs.

It is contemplated that the embodiments ofFIGS. 7 and 8in which the first scroll compressor body110includes four radially-outward projecting limit tabs111,113, these limit tabs111,113could provide radial restraint of the first scroll compressor body110, as well as axial and rotation restraint. For example, radially-outward projecting limit tabs113could be configured to fit snugly with notched sections166such that these limit tabs113sufficiently limit radial movement of the first scroll compressor body110along first lateral axis146. Additionally, each of the radially-outward-projecting limit tabs111could have a notched portion configured to abut the portion of the first inner wall169adjacent the slots162of the pilot ring160to provide radial restraint along second lateral axis154. While this approach could potentially require maintaining a certain tolerance for the limit tabs111,113or the notched section166and slots162, in these instances, there would be no need to precisely tolerance the entire first inner wall169of the pilot ring160, as this particular feature would not be needed to provide radial restraint of the first scroll compressor body110.

With reference toFIGS. 9-12, the upper side (e.g. the side opposite the scroll rib) of the fixed scroll110supports a floating seal170above which is disposed the separator plate30. In the embodiment shown, to accommodate the floating seal170, the upper side of the fixed scroll compressor body110includes an annular and, more specifically, the cylindrical inner hub region172, and the peripheral rim174spaced radially outward from the inner hub region172. The inner hub region172and the peripheral rim174are connected by a radially-extending disc region176of the base116. As shown inFIG. 11, the underside of the floating seal170has circular cutout adapted to accommodate the inner hub region172of the fixed scroll compressor body110. Further, as can be seen fromFIGS. 9 and 10, the perimeter wall173of the floating seal is adapted to fit somewhat snugly inside the peripheral rim174. In this manner, the fixed scroll compressor body110centers and holds the floating seal170with respect to the central axis54.

In a particular embodiment of the invention, a central region of the floating seal170includes a plurality of openings175. In the embodiment shown, one of the plurality of openings175is centered on the central axis54. That central opening177is adapted to receive a rod181which is affixed to the floating seal170. As shown inFIGS. 9 through 12, a ring valve179is assembled to the floating seal170such that the ring valve179covers the plurality of openings175in the floating seal170, except for the central opening177through which the rod181is inserted. The rod181includes an upper flange183with a plurality of openings185therethrough, and a stem187. As can be seen inFIG. 9, the separator plate30has a center hole33. The upper flange183of rod181is adapted to pass through the center hole33, while the stem187is inserted through central opening177. The ring valve179slides up and down the rod181as needed to prevent back flow from a high-pressure chamber180. With this arrangement, the combination of the separator plate30and the fixed scroll compressor body110serve to separate the high pressure chamber180from a lower pressure region188within the outer housing12. Rod181guides and limits the motion of the ring valve179. While the separator plate30is shown as engaging and constrained radially within the cylindrical side wall region32of the top end housing section26, the separator plate30could alternatively be cylindrically located and axially supported by some portion or component of the scroll compressor14.

In certain embodiments, when the floating seal170is installed in the space between the inner hub region172and the peripheral rim174, the space beneath the floating seal170is pressurized by a vent hole (not shown) drilled through the fixed scroll compressor body110to chamber122(shown inFIG. 2). This pushes the floating seal170up against the separator plate30(shown inFIG. 9). A circular rib182presses against the underside of the separator plate30forming a seal between high-pressure discharge gas and low-pressure suction gas.

While the separator plate30could be a stamped steel component, it could also be constructed as a cast and/or machined member (and may be made from steel or aluminum) to provide the ability and structural features necessary to operate in proximity to the high-pressure refrigerant gases output by the scroll compressor14. By casting or machining the separator plate30in this manner, heavy stamping of such components can be avoided.

During operation, the scroll compressor assembly10is operable to receive low-pressure refrigerant at the housing inlet port18and compress the refrigerant for delivery to the high-pressure chamber180where it can be output through the housing outlet port20. This allows the low-pressure refrigerant to flow across the electrical motor assembly40and thereby cool and carry away from the electrical motor assembly40heat which can be generated by operation of the motor. Low-pressure refrigerant can then pass longitudinally through the electrical motor assembly40, around and through void spaces therein toward the scroll compressor14. The low-pressure refrigerant fills the chamber31formed between the electrical motor assembly40and the outer housing12. From the chamber31, the low-pressure refrigerant can pass through the upper bearing member or crankcase42through the plurality of spaces244that are defined by recesses around the circumference of the crankcase42in order to create gaps between the crankcase42and the outer housing12. The plurality of spaces244may be angularly spaced relative to the circumference of the crankcase42.

After passing through the plurality of spaces244in the crankcase42, the low-pressure refrigerant then enters the intake area124between the fixed and movable scroll compressor bodies110,112. From the intake area124, the low-pressure refrigerant enters between the scroll ribs114,118on opposite sides (one intake on each side of the fixed scroll compressor body110) and is progressively compressed through chambers122until the refrigerant reaches its maximum compressed state at the compression outlet126from which it subsequently passes through the floating seal170via the plurality of openings175and into the high-pressure chamber180. From this high-pressure chamber180, high-pressure compressed refrigerant then flows from the scroll compressor assembly10through the housing outlet port20.

FIGS. 13 and 14illustrate an alternate embodiment of the invention. Instead of a crankcase42formed as a single piece,FIGS. 13 and 14show an upper bearing member or crankcase199combined with a separate collar member198, which provides axial thrust support for the scroll compressor14. In a particular embodiment, the collar member198is assembled into the upper portion of the upper bearing member or crankcase199along stepped annular interface100. Having a separate collar member198allows for a counterweight230to be assembled within the crankcase199, which is attached to the pilot ring160. This allows for a more compact assembly than described in the previous embodiment where the counterweight130was located outside of the crankcase42.

As is evident from the exploded view ofFIG. 13and as stated above, the pilot ring160can be attached to the upper bearing member or crankcase199via a plurality of threaded fasteners to the upper bearing member199in the same manner that it was attached to crankcase42in the previous embodiment. The flattened profile of the counterweight230allows for it to be nested within an interior portion201of the upper bearing member199without interfering with the collar member198, the key coupling140, or the movable scroll compressor body112.

For purposes of this disclosure, the term “coupled” means the joining of two components (electrical or mechanical) directly or indirectly to one another. Such joining may be stationary in nature or moveable in nature. Such joining may be achieved with the two components (electrical or mechanical) and any additional intermediate members being integrally formed as a single unitary body with one another or the two components and any additional member being attached to one another. Such adjoining may be permanent in nature or alternatively be removable or releasable in nature.