Abstract:
A method of manufacturing a compressor housing assembly including a drawn race bearing assembly. The method comprises the steps of: providing a housing body having a face surface; machining a shaft bore through the face surface; press fitting a drawn outer race into the shaft bore; machining at least one piston cylinder bore into the face surface after the outer race is positioned in the shaft bore; and securing a roller assembly within the shaft bore in alignment with the drawn outer race.

Description:
BACKGROUND  
         [0001]    The present invention relates to radial bearing assemblies. More particularly, the present invention relates to a radial bearing assembly positioned within an internal bore of a housing, for example, a shaft bore in a swashplate air conditioning compressor assembly.  
           [0002]    An example of a fixed displacement compressor assembly  5  incorporating the present invention is illustrated in section in FIG. 1. The compressor assembly  5  includes a main shaft  10  supported in shaft bores  20  extending through opposed, interconnected housings  12 . The shaft  10  is supported in each shaft bore  20  by a respective radial bearing assembly  50 .  
           [0003]    Referring to FIG. 2, each housing  12  has the shaft bore  20 , a plurality of compressed fluid passages  22  and a plurality of cylinder bores  24 . The cylinder bores  24  are configured for reciprocating motion of pistons  16  therein. A clearance between the piston  16  and respective cylinder bore  24  is necessary for smooth operation of the piston  16 , but it is desirable to minimize the clearance to prevent fluid leakage and maximize the compressor efficiency.  
           [0004]    To ensure the proper piston clearance, the cylinder bores  24  are precisely machined and steps are taken to avoid any distortion of the cylinder bores  24 . Such distortion may compromise the fit between the piston  16  and the cylinder bore  24 , resulting in a reduced compressor efficiency. In this effort, machined race roller bearings are generally used for radial shaft  10  support. The machined race bearings can be manufactured to tight tolerances and require little or no press fitting into the shaft bore  20 , thereby reducing the potential for cylinder bore  24  distortion during insertion of the machined race bearing. While the machined race bearings are effective, they are relatively expensive to manufacture.  
           [0005]    Accordingly, there is a desire for a method to provide a bearing assembly utilizing a fairly inexpensive, effective radial bearing assembly that can be installed in a compressor shaft bore  20  while maintaining a limited risk of distorting the cylinder bores  24 .  
         SUMMARY  
         [0006]    The present invention provides a method of manufacturing a compressor housing assembly including a drawn race bearing assembly. The method comprises the steps of: providing a housing body having a face surface; machining a shaft bore through the face surface; press fitting a drawn outer race into the shaft bore; machining at least one piston cylinder bore into the face surface after the outer race is positioned in the shaft bore; and securing a roller assembly within the shaft bore in alignment with the drawn outer race.  
           [0007]    Various drawn race bearing assemblies for use in accordance with the method are also provided. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a cross-sectional view of an air compressor assembly incorporating radial bearing assemblies that are a first embodiment of the present invention.  
         [0009]    [0009]FIG. 2 is an isometric view of a housing of the air compressor assembly of FIG. 1.  
         [0010]    [0010]FIGS. 3 and 4 are isometric and planar, respectively, cross-sectional views of a portion of the housing assembly taken along the line  3 - 3  in FIG. 2 with an illustrative roller cage assembly aligned therewith.  
         [0011]    FIGS.  5 - 8  are progressive isometric views illustrating the preferred method of manufacturing the housing of FIG. 2.  
         [0012]    [0012]FIGS. 9 and 10 are isometric and planar, respectively, cross-sectional views similar to FIGS. 3 and 4 illustrating a second embodiment of the present invention.  
         [0013]    [0013]FIGS. 11 and 12 are isometric and planar, respectively, cross-sectional views similar to FIGS. 3 and 4 illustrating a third embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]    The present invention will be described with reference to the accompanying drawing figures wherein like numbers represent like elements throughout. Certain terminology, for example, “top”, “bottom”, “right”, “left”, “front”, “frontward”, “forward”, “back”, “rear” and “rearward”, is used in the following description for relative descriptive clarity only and is not intended to be limiting.  
         [0015]    Referring to FIGS. 3 and 4, a bearing assembly  50  in accordance with a first embodiment of the present invention is illustrated. The preferred bearing assembly  50  includes a drawn outer race  52 , a roller assembly  60  and a retainer assembly  70 . The drawn cup outer race  52  includes an inner lip  54  and a circumferential raceway surface  56  with the end  58  opposite the inner lip  54  being substantially open. The inner lip  54  provides an inner retention surface for the roller assembly  60 . The drawn outer race  52  is preferably manufactured from a hardened steel blank with a hardness of approximately 58 HRC that is drawn using known techniques. The drawn outer race  52  has an outside diameter that is equal to, and preferably slightly greater than, the inside diameter of the shaft bore  20  at the intended location of the bearing assembly. As such, the drawn cup outer race  52  is press fit into and retained in the shaft bore  20 .  
         [0016]    The preferred roller assembly  60  includes a plurality of rollers  62  maintained within a cylindrical cage  64 . Other roller assemblies  60  may also be utilized. The open end  58  of the drawn outer race  52  allows the roller assembly  60  to be easily positioned within the outer race  52  with the cage  64  retained on one side by the inner lip  54 . After the roller assembly  60  is inserted, the retainer assembly  70  is inserted into the shaft bore  20  to capture the roller assembly  60  within the drawn outer race  52 . The retainer assembly  70  preferably includes a hardened washer  72  adjacent the roller assembly cage  64  and a retainer ring  74  that is secured within the shaft bore  20 . The retainer ring  74  is preferably a split ring manufactured from a polymer material, for example, a plastic, having an outside diameter slightly greater than inside diameter of the shaft bore  20 . The retainer ring  74  is snapped into the shaft bore  20  with an interference fit to retain the washer  72  and thereby the roller assembly  60 . The plastic character of the retainer ring  74  reduces the potential for distortion of the cylinder bores  24 . In a situation where the drawn outer race  52  is the same length as the bearing bore and an end plate of suitable wear resistance exists in the compressor design, the end plate replaces the retainer assembly  70 .  
         [0017]    Referring to FIGS.  5 - 8 , the preferred method of manufacturing the bearing assembly  50  and positioning it within the housing  12  is illustrated. Referring to FIG. 5, the housing  12  is preferably cast with somewhat rough fluid passages  22 ′ and cylinder bores  24 ′. The shaft bore  20  is also somewhat rough, but is finished, for example, by machining, boring or another finishing technique. Finishing as used herein incorporates various methods, but generally relates to finishing the surface to desired characteristics, for example, desired dimensions and smoothness. While the bores  20 ,  24  and passages  22  are preferably cast in the housing  12 , other methods can also be used. For example, the bores  20 ,  24  and passages  22  may be machined into a solid housing (not shown). Also, while it is preferable to finish the fluid passages  22  at the same time as the cylinder bores  24 , such may not be necessary as the passages  22  do not require as tight tolerances.  
         [0018]    The drawn outer race  52  is press fit into the shaft bore  20  to a desired position as indicated by the arrow A in FIG. 6. After the drawn outer race  52  has been inserted, each of the fluid passages  22  and cylinder bores  24  is finished as illustrated in FIG. 7. Since the drawn outer race  52  is already positioned, it does not impact the finishing of the cylinder bore  24 . The cylinder bores  24  can be finished to any desired tolerance. After the bores  22  and  24  are finished, the roller assembly  60  is inserted into the drawn outer race  52  and secured by the retainer assembly  70 , as indicated by arrow B in FIG. 8. Since the insertion of the roller assembly  60  and the retainer assembly  70  do not exert an excessive outward force on the shaft bore  20 , the risk of cylinder bore  24  distortion is minimized.  
         [0019]    Referring to FIGS. 9 and 10, a roller bearing assembly  100  that is a second embodiment of the present invention is illustrated. The bearing assembly  100  includes a drawn outer race  102 , a roller assembly  110  and an inverted drawn inner race  120 . The drawn outer race  102  is similar to drawn outer race  52 , but preferably does not include an inner lip, but instead is substantially open at both ends. The circumferential portion  106  of the drawn outer race  102  has an outer diameter slightly larger than the inside diameter of the shaft bore  20  and is press fit therein. As in the previous embodiment, the outer drawn race  102  is press fit into the shaft bore  20  prior to finishing of the cylinder bores  24 . The inverted drawn inner race  120  is formed with a circumferential inner surface  122  and opposed lips  124  and  126  substantially perpendicular thereto. The drawn inner race  120  is preferably formed with the roller assembly  110  retained therein, i.e., the roller assembly  110  is positioned about the circumferential inner surface  122  prior to formation of the second lip  126 . Alternatively, the roller assembly  110  may be a split cage assembly that is positioned about the inner surface  122  after drawing of both lips  124 ,  126 . The drawn inner race  120  is positioned about and secured to the shaft  10  to define the positioning of the roller assembly  110 . The drawn inner race  120  is preferably press fit onto the shaft  10 , however, other connection methods, for example, the use of splines, may also be used. With the inner race  120  positioned thereabout, the shaft  10  is extended through the shaft bore  20  until the roller assembly  110  is aligned with the drawn outer race  102 . Insertion of the shaft  10  with the drawn inner race  120  and roller assembly  110  thereabout provides little risk of cylinder bore  24  distortion.  
         [0020]    Referring to FIGS. 11 and 12, a roller bearing assembly  150  that is a third embodiment of the present invention is illustrated. The bearing assembly  150  includes a drawn outer race  152  and a split ring roller assembly  160 . The drawn outer race  152  is similar to drawn outer race  52 , but includes inner and outer lips  154  and  158  on opposite sides of the circumferential portion  156 . Again, the circumferential portion  156  of the drawn outer race  152  has an outer diameter slightly larger than the inside diameter of the shaft bore  20  and is press fit therein. As in the previous embodiments, the outer drawn race  152  is press fit into the shaft bore  20  prior to machining of the cylinder bores  24 . The roller assembly  160  preferably includes a plurality of rollers  162  maintained in a polymer split ring cage  164 . The illustrated cage  164  has two interlocking halves  166  and  168 . After finishing of the cylinder bores  24 , a first half  166  of the cage  164  is positioned in the pre-positioned drawn outer race  152  and then the second half  168  of the cage  164  is positioned in the outer race  152  and interconnected with the first half  166 . The polymer material allows the cage  164  sufficient flexibility to be positioned within the opposed outer race lips  154  and  158 . Additionally, the cage  164  can be split into more than two pieces to further facilitate insertion. Alternatively, the split cage  164  can be a single unit with only one split. The flexible nature of the cage  164  allows it to be compressed upon itself and then snapped into the drawn outer race  152  after positioning therein. Insertion of the split cage  164  provides little risk of cylinder bore  24  distortion.