Powder metal scroll hub joint

A scroll component including a spiral scroll wrap, a baseplate having a first major surface coupled to the scroll wrap and a second opposing major surface comprising a protruding pilot extending a distance from the baseplate, and a hub fastened to the baseplate adjacent to the protruding pilot. A method of forming a scroll compressor element is also provided.

FIELD

The present teachings relate to scroll machines, and more particularly, to a scroll compressor.

BACKGROUND

Scroll-type machines are commonly used as compressors in both refrigeration as well as air conditioning applications due primarily to their capability for extremely efficient operation. Unlike reciprocating technology with many moving parts, a typical scroll compressor has one scroll orbiting in a path defined by a matching non-orbiting scroll, which is attached to a compressor body. The orbiting scroll is coupled to a crankshaft in orbit, which creates a series of moving or successive gas chambers traveling between the two scrolls. On the outer portion of the scroll, a pocket draws in gas, which is compressed as the gas moves through a series of successive, increasingly smaller, moving chambers until the gas is discharged through a central port in the non-orbiting scroll.

Scroll compressors depend upon a number of seals to create and define the moving chambers. To perform properly, the scrolls must not leak, wear out or fracture. The costs associated with machining can be quite significant due to the complex shape of the scrolls themselves, the machining of grooves, and the assembly of these components.

Typical powder metal scrolls are commonly assembled by forming two individual pieces, a baseplate having a scroll wrap and a hub, and joining them together to form a scroll component. One current method of joining the two pieces together uses a brazing process. While this process is adequate for producing the scroll components, it also results in a braze joint that is situated in a potentially high stress zone, subject to localized high stresses due to the bearing loads applied to the hub. Joints that are located in high stress zones are more prone to failure as compared to joints located in lower stress zones.

SUMMARY

The present teachings are generally directed toward a scroll compressor, and more particularly to the joints of a scroll component for a scroll compressor. In one aspect, the scroll component includes a spiral scroll wrap and a baseplate having first and second opposing major surfaces. The first major surface is coupled to the scroll wrap and the second major surface includes a raised shoulder extending a distance from the baseplate. A cylindrical hub may be fastened to the raised shoulder. At least one portion of the scroll component may include a powdered metal material and the hub may be brazed to the raised shoulder.

The present teachings also provide a scroll component including a first member having a first baseplate portion and an integral spiral scroll wrap, and a second member having a second baseplate portion and an integral cylindrical hub. The first member may be joined to the second member to form a unitary scroll component.

The present teachings also provide a scroll component including a spiral scroll wrap and a baseplate. The baseplate has a first major surface coupled to the scroll wrap and a second opposing major surface including a protruding pilot extending a distance from the baseplate. A hub may be aligned with the protruding pilot and brazed to the baseplate adjacent the protruding pilot. The protruding pilot may include an annular wall.

The present teachings also provide a scroll component including a baseplate having a first major surface coupled to a scroll wrap, and a second opposing major surface having an annular tapered recess. A cylindrical hub having a tapered edge may be brazed to the tapered recess.

The present teachings also provide a scroll component including a baseplate having a first major surface coupled to a scroll wrap and a second opposing major surface having a protruding cone-shaped center pilot. A cylindrical hub may be brazed to the baseplate and surrounds the center pilot.

The present teachings also provide a method of forming a scroll compressor element. The method includes providing a baseplate having a first major surface coupled to a scroll wrap and a second opposing major surface having a protruding pilot. A cylindrical hub member is aligned with the protruding pilot. A braze material is provided adjacent at least one or both of the protruding pilot and the hub member. The hub member is then brazed to the baseplate. The protruding pilot may include a cone shape, and providing a braze material may include placing braze pellets on the protruding pilot and allowing the pellets to roll to an inside diameter of the hub member, or placing a ring of braze material onto the baseplate, the ring having a diameter sufficient to mate with the inside of the hub member, or placing a brazing paste on to the baseplate.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is in no way intended to limit the teachings, its application, or uses.

Referring to the drawings in which like reference numerals designate like or corresponding parts throughout the several views,FIG. 1illustrates an exemplary scroll compressor10that is capable of incorporating a representative scroll component in accordance the present teachings. The compressor10includes a generally cylindrical hermetic shell12having a cap14welded at the upper end thereof and a base16at the lower end optionally having a plurality of mounting feet (not shown) integrally formed therewith. The cap14is provided with a refrigerant discharge fitting18which may have the usual discharge valve therein (not shown). Other major elements affixed to the shell include a transversely extending partition22welded about its periphery at the same point that the cap14is welded to the shell12, a main bearing housing24suitably secured to the shell12, and a lower bearing housing26also having a plurality of radially outwardly extending legs, each of which is also suitably secured to the shell12. A motor stator28, which is generally polygonal in cross-section, e.g., 4 to 6 sided, with rounded corners, is press fitted into the shell12. The flats between the rounded corners on the stator provide passageways between the stator and shell, which facilitate the return flow of lubricant from the top of the shell to the bottom.

A drive shaft or crankshaft30having an eccentric crank pin32at the upper end thereof is rotatably journaled in a bearing34in the main bearing housing24. A second bearing36is disposed in the lower bearing housing26. The crankshaft30has a relatively large diameter concentric bore38at the lower end which communicates with a radially outwardly inclined smaller diameter bore40extending upwardly therefrom to the top of the crankshaft30. A stirrer42is disposed within the bore38. The lower portion of the interior shell12defines an oil sump44filled with lubricating oil to a level slightly lower than the lower end of a rotor46but high enough to immerse a significant portion of the lower end turn of the windings48. The bore38acts as a pump to pump lubricating fluid up the crankshaft30and into the passageway40and ultimately to all of the various portions of the compressor which require lubrication.

The crankshaft30is rotatively driven by an electric motor including a stator28and windings48passing therethrough. The rotor46is press fitted on the crankshaft30and has upper and lower counterweights50and52, respectively.

The upper surface of the main bearing housing24is provided with a flat thrust bearing surface54on which an orbiting scroll member56is disposed having the usual spiral vane or wrap58on the upper surface thereof. A cylindrical hub90downwardly projects from the lower surface of orbiting scroll member56and has a bearing bushing60therein. A drive bushing62is rotatively disposed in the bearing bushing60and has an inner bore64in which a crank pin32is drivingly disposed. Crank pin32has a flat on one surface which drivingly engages a flat surface formed in a portion of the bore64to provide a radially compliant driving arrangement, such as shown in U.S. Pat. No. 4,877,382, the disclosure of which is hereby incorporated herein by reference. An Oldham coupling66is provided positioned between the orbiting scroll member56and the bearing housing24and is keyed to the orbiting scroll member56and a non-orbiting scroll member68to prevent rotational movement of the orbiting scroll member56. The Oldham coupling66may be of the type disclosed in U.S. Pat. No. 5,320,506, the disclosure of which is hereby incorporated herein by reference.

The non-orbiting scroll member68includes a wrap70positioned in meshing engagement with the wrap58of the orbiting scroll member56. The non-orbiting scroll member68has a centrally disposed discharge passage72that communicates with an upwardly open recess74in fluid communication with a discharge muffler chamber76defined by the cap14and the partition22. An annular recess78may be formed in the non-orbiting scroll member68within which a seal assembly80is disposed. The recesses74,78and the seal assembly80cooperate to define axial pressure biasing chambers to receive pressurized fluid compressed by the wraps58,70so as to exert an axial biasing force on the non-orbiting scroll member68to urge the tips of the respective wraps58,70into sealing engagement with the opposed end plate surfaces. The seal assembly80may be of the type described in greater detail in U.S. Pat. No. 5,156,539, the disclosure of which is hereby incorporated herein by reference. The non-orbiting scroll member68may be designed to be mounted to the bearing housing24in a suitable manner such as disclosed in the aforementioned U.S. Pat. No. 4,877,382 or U.S. Pat. No. 5,102,316, the disclosure of which is hereby incorporated herein by reference.

FIG. 2illustrates an exploded perspective view of an orbiting scroll member56andFIG. 3Ais a cross-sectional view of an assembled orbiting scroll member as illustrated inFIG. 2. As shown, the orbiting scroll member56may include a generally circular baseplate82having first and second generally planar opposing major surfaces represented by reference numbers84and86, respectively. The first major surface84may be coupled to the spiral scroll wrap58. The second major surface86may include a raised portion such as an annular raised shoulder88as shown inFIG. 3A, or a raised cylindrical pad89as shown inFIG. 3B, extending a distance generally perpendicular to the baseplate82. The scroll wrap58and the baseplate82may be one monolithic component formed out of powdered metal using techniques known in the art, such as disclosed in U.S. Pat. No. 6,705,848, the disclosure of which is hereby incorporated herein by reference, or may include multiple components joined together such as by using brazing materials to join a scroll wrap58to a baseplate82. The components may also be produced from a powder metal or wrought material.

A cylindrical hub member90may include first and second opposing edges92,94. The hub member90may be formed using wrought material, standard casting techniques or other forming processes, including powdered metal, and is fastened to the baseplate82. For example, the hub member90may be brazed to the raised shoulder88, or raised pad89, at a joint96using typical brazing methods known to those skilled in the art. It may also be brazed using methods suitable for use with powdered metal materials. For example, the green components can be assembled and brazed together while the powder metal component is sintered. A solid hub may be fastened utilizing materials that harden during the sintering process.

With reference toFIG. 3A, the raised shoulder88(or cylindrical pad89ofFIG. 3B) may extend a distance D1from the second major surface86. This distance D1may be from about 5 to about 20 times less than the base plate82thickness. The hub edge92and raised shoulder edge98may be provided with complementary tapered angles configured to mate and form a tapered joint96. The angle of the tapered surface to the base plate may be between about 0 and about 20 degrees. Phantom lines, as shown inFIG. 3A(and other figures), illustrate the form of the scroll components prior to any machining, if desired, as the parts are assembled and sintered. After assembled, the scroll56may be machined having a final shape as shown inFIG. 3B. A slightly recessed annular groove or recessed channel100may be initially formed or subsequently machined around the raised shoulder88, or cylindrical pad89, prior to the hub member90being brazed to the baseplate82if desired. The channel100may serve as a braze dam that assists in minimizing any flow of braze material onto a thrust surface of the scroll member56. Additionally, the lower edge94of the hub member90may be machined with angled or rounded corners95.

The use of a raised shoulder88, or raised pad89, may increase the overall strength of the scroll member56by moving the actual braze joint location96away from one of the highest localized stress zones, which is the mid-radius point, or thereabout, as designated by reference number97. This area97typically exhibits the most applied bearing loads during use, and is now slightly removed from the hub and baseplate braze joint by the use of the raised should88or pad89.

FIG. 3Billustrates the raised pad89feature where the centralized portion of the baseplate82that is joined to the hub90is raised completely across, to simplify the overall part structure. As previously discussed, the hub member90may be joined to the baseplate82with a brazing process. During the brazing process, it may be necessary to align and retain the hub member90in an intended final brazing position with respect to the baseplate82and to prevent and/or minimize any movement away from the intended joint96. As shown in this embodiment, the baseplate may be provided with an integral recessed pilot, or vane101, and the hub90may be provided with an external protruding pilot103for consistent pre-assembly placement and alignment of the of the hub90onto the baseplate82, before they are brazed together. As illustrated, the protruding pilot103has a substantially rectangular cross-section. However, as should be understood to those skilled in the art, the pilot cross-section may also be triangular, semi-circular, etc.

FIG. 4Aillustrates a cross sectional view of a scroll component56depicting another aspect of the present teachings. Similar toFIGS. 3A and 3B, the baseplate82has a first major surface84coupled to the scroll wrap58and a second opposing major surface86with an annular recess110. To aid alignment, the annular recess110of the baseplate82may include a protruding pilot102extending a distance D2generally perpendicular to the baseplate82. The distance D2may be about 2 to about 20 times smaller than the thickness of the baseplate. The hub member90may be fastened, e.g., brazed, to the baseplate82adjacent the protruding pilot102.

The protruding pilot102may be an annular wall that assists in aligning the hub member90with the baseplate82and to minimize any shifting, misalignment, or movement between the hub90and the baseplate82during the fastening process. The annular wall may be a continuous ring-shaped protrusion, or may include a plurality of discontinuous sections (not shown) configured to serve the same purpose. The protruding pilot102may be formed having a generally hollow cylindrical shape, or may be formed having one or more angled or tapered sides104that do not allow excessive shifting or movement of the hub member90with respect to the baseplate82.

The baseplate82may include an annular recessed area110circumferentially disposed around the protruding pilot102and configured to be joined with an edge92of the hub member90. As shown, the recessed area can be sized slightly larger than the edge92of the hub member90to provide a small gap area112for excess brazing material as will be described in more detail below. The recessed area110may be tapered and the hub member may include a complementary tapered edge configured to mate with the baseplate recess110and form a tapered joint96.

As shown inFIG. 4B, which illustrates a partial bottom plan view of a center portion of the baseplate82, the protruding pilot may be disposed on the baseplate82such that its outermost edge106is adjacent to and abuts the inner diameter (ID) of the hub member90. In other aspects, the protruding pilot may be disposed on the baseplate82such that it would surround the hub member90and have an innermost edge108abutting the outer diameter (OD) of the hub member90.

FIG. 5illustrates a cross-sectional view of a scroll component56including a first member116including a first baseplate portion118and an integral scroll wrap58. A second member120may include a second baseplate portion124and an integral cylindrical hub portion126. The first member116is joined to the second member120at a joint128, such as by brazing the first baseplate portion to the second baseplate portion, to form a unitary scroll component56.

As shown, the first baseplate portion118and the second baseplate portion124are of equivalent diameter and each include roughly half of the width, or thickness, of the baseplate82. The dimensions of each portion118,124are not required to be the same, however, and suitable variations are within the scope of the present teachings. At least one or both of the baseplate portions118,124may include a protruding pilot130to assist in providing uniform and accurate alignment of the first and second members116,120prior to brazing. Accordingly, at least one or both of the baseplate portions118,124may also include an internal, or recessed pilot132, configured to mate with the protruding pilot130. Additionally, the lower edge94of the hub member90may be machined with angled or rounded corners95.

FIG. 6illustrates an exploded perspective view of an orbiting scroll component56with the baseplate82having a first major surface84coupled to a scroll wrap58and a second opposing major surface86having a protruding cone shaped center pilot134.FIG. 7illustrates a partial magnified perspective view of the center pilot134area of the baseplate82ofFIG. 6. The baseplate surface86may further define an annular tapered recess136surrounding the center pilot134. The annular recess136may be tapered to mate with a tapered edge92of the hub member90to form a tapered joint96.

FIG. 8illustrates a cross-sectional view ofFIG. 6taken along the reference line8-8.FIG. 9is a partial magnified view ofFIG. 8depicting a center point138of the cone shaped pilot134. The tapered, cone shaped protruding pilot134assists spherical shaped braze pellets to roll to the inner diameter of the hub member90prior to the brazing process. The annular recess136of the baseplate82may be sized having a width slightly larger than a width of the tapered edge92of the hub member90such that there is a slight extension148as best shown inFIG. 10, which is a partial magnified view ofFIG. 9.FIG. 11is a variation ofFIG. 9illustrating the outer edge areas of the joint96after a machining process. In this regard,FIG. 11shows an exterior coupling radius formed on the hub90.FIG. 12illustrates a further orientation of the joint96between the hub member90and the baseplate82where the angle of the joint96is reversed.

As best seen inFIGS. 6,7,10, and11, the annular recess136can have a plurality of protrusion137radially disposed about the annular recess. In this regard, the protrusion137is configured to control the gap between the hub90and the annular recess136. This allows for the proper flow and distribution of the braze material between the hub90and the annular recess136.

A method of joining a cylindrical hub member to a baseplate of a scroll component includes providing a baseplate having a first major surface coupled to a scroll wrap and a second opposing major surface having a protruding pilot. The cylindrical hub member is aligned with the protruding pilot, and a braze material, such as a braze paste, or spherical braze pellets are provided adjacent at least one or both of the protruding pilot and the hub member. The protruding pilot may include a cone shape and providing a braze material may include placing braze pellets on the protruding pilot and allowing the pellets to roll to an inside diameter of the hub member prior to the brazing process. In other aspects, a ring of braze material is placed onto the baseplate having a diameter sufficient to mate with the inside of the hub member. The hub member is then brazed to the baseplate, and any desired machining of the scroll component can be performed.

The description is merely exemplary in nature and, thus, variations are intended to be within the scope of the teachings.