Abstract:
A housing assembly for a refrigerant compressor in an air conditioning system includes a forward housing portion, and a rearward housing portion. The two mate together to contain the internal components and seal the compressor. A clamp engages the forward and the rearward housing portions and is rotated to compress the two together. It maintains a desired clamping force under various operating and environmental conditions.

Description:
BACKGROUND OF INVENTION 
     The present invention relates to air conditioning compressors and more particularly to the housings for air conditioning compressors. 
     Conventionally, for compressors employed in the air conditioning systems of vehicles, the housing is assembled from at least two separate parts. Typically, bolts are employed to hold the separate parts of the housing together. The bolts not only hold the housing together, but they also must provide a certain compressive load in order to assure that the housing seals properly. If not, refrigerant can leak out. A housing that is held together with bolts is not particularly well suited for this because the housing is usually made out a aluminum and the bolts are made out of steel. These materials have different thermal expansion characteristics. When the temperature in the engine compartment of a vehicle changes dramatically, the aluminum housing and the steel bolts expand at different rates, which changes the amount of compressive load—thus, the clamping loads can vary substantially from the clamping loads obtained during assembly of the compressor. 
     The appropriate clamping load can be very important to assuring that the housing seals adequately. This is particularly true as new refrigerants may be used in the near future that operate in much higher pressure ranges than current refrigerants. Thus, it is desirable to have a housing assembly for an air conditioning compressor that overcomes the drawbacks of the bolted together housing assemblies. In particular, one that will allow for adequate sealing of the housing, while still remaining simple to assemble, light weight and cost effective, as is required to meet the demands in today&#39;s automotive vehicles. 
     SUMMARY OF INVENTION 
     In its embodiments, the present invention contemplates a compressor for an air conditioning system. The compressor includes a first housing with an outer wall having an end with external threads thereon and an inner wall defining an inner cavity, and a component mounted partially within the inner cavity that has an outer surface sealingly engaging the inner wall. The compressor also includes a second housing having an inner wall defining an inner cavity for sealingly receiving a portion of the component along the component outer surface, and with the second housing including an engagement portion having an engagement device thereon. A clamping member, having a generally hollow cylindrical shape, includes a first set of internal threads that threadably engage the external threads on the first housing, and includes a second engagement device operatively engaging the engagement portion of the second housing such that rotation of the clamping member in a first direction will cause the first and the second housings to be pulled toward one another, and rotation of the clamping member in a second opposite direction will allow the first and the second housings to be pushed away from one another. 
     An advantage of the present invention is that the components of an air conditioning compressor housing can be assembled together and seal adequately within a wide temperature range. 
     Another advantage of the present invention is that the air conditioning compressor housing assembly is cost effective, assembles relative easily and minimizes the weight of the overall housing. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a side view of a portion of a compressor assembly in accordance with the present invention; 
     FIG. 2 is a sectional view of a portion of the compressor assembly in accordance with the present invention; 
     FIG. 3 is a view of encircled area  3  in FIG. 2, on an enlarged scale; 
     FIG. 4 is a perspective view of a ring clamp in accordance with the present invention; 
     FIG. 5 is a perspective view of the cylinder housing in accordance with the present invention; and 
     FIG. 6 is a schematic sectional view, similar to FIG. 3 but illustrating a second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1-5 illustrate a first embodiment of an air conditioning compressor housing assembly  20 , in accordance with the present invention. The housing assembly  20  is designed to form a portion of a piston-type refrigerant compressor. The pistons, drive mechanism, and other components are not illustrated herein, but are conventional in nature and are well know to those skilled in the art of refrigerant compressors for automotive vehicles. For example, the other components may be similar to those of a swash plate refrigerant compressor, as disclosed in U.S. Pat. No. 6,318,972, incorporated herein by reference. While the example in the preferred embodiment illustrates a compressor housing for a swash plate type of compressor, the present invention is also applicable to other types of refrigerant compressors as well. 
     The housing assembly  20  includes a front housing portion  22  (also sometimes called a crankcase), a rear housing portion  21  (also sometimes called a cylinder head), a cylinder block  23 , a valve plate assembly  27 , and a ring clamp  31 . When referring to front and rear herein, the wording is merely used for convenience in describing the assembly and the orientation of the parts relative to one another, but does not imply any particular orientation of the assembly within a vehicle. 
     The front housing portion  22 , rear housing portion  21 , and the ring clamp  31  are preferably made of aluminum, although they may be made of other materials. Preferably, these three components are all formed from the same material in order to reduce the effect of any thermal stresses—although they can be different materials if required. The valve plate  27  is preferably made of steel, although it may also be made of other materials. 
     The front housing portion  22  has a cylindrical wall  24  integral with an end wall  25 . The end wall  25  includes a driveshaft passage  29  therethrough. The cylindrical wall  24  includes an outer surface  26 , and an inner surface  32 , which defines an inner cavity  28  (also called a crankcase cavity) open at its rear end. The cylindrical wall  24  also includes a first set of external threads  30  on its outer surface  26  surrounding the opening at the rear end of the front housing  22 . A pair of mounting bosses  34  extend from the front housing  22 , and are use to mount the housing  20  in an engine compartment of a vehicle (not shown). 
     The cylinder block  23  has a forward, outer surface  36 , which is generally cylindrical and slides within the inner cavity  28  with a small clearance between the outer surface  36  and the inner surface  32  of the front housing  22 . A first O-ring seal  38  mounts within a seal recess and presses against the inner surface  32 , sealing between the front housing  22  and the cylinder block  23 . The cylinder block also includes a rearward, outer surface  40 , which is generally cylindrical in shape. It includes a seal recess within which is mounted a second  0 -ring seal  42 . The cylinder block  23  has six piston cylinders  44  extending therethrough, twelve weight reduction bores  46 , and a central bore  48  for receiving and mounting a shaft and bearing assembly (not shown). 
     The rear face  55  of the cylinder block  23  includes a recess around each piston cylinder opening for receiving cylinder O-ring seals  53 , which seal between the rear face  55  and the valve plate assembly  27 . In the alternative, a gasket can be used between the rear face  55  of the cylinder block  23  and the valve plate  27 , although this may require a higher clamp load in order to provide the desired sealing. 
     The cylinder block  23  can be formed from aluminum, steel or iron. It can be made of iron without concerns with possible corrosion because it is completely sealed within the front housing portion  22  and rear housing portion  21 , and so it is not exposed to the environment external to the housing assembly  20 . 
     The rear housing portion  21  includes an outer, cylindrical wall  50 , which encloses a suction chamber  52  and a discharge chamber  54 , as well as various passages (only partially shown) for receiving refrigerant into and sending refrigerant out of the compressor housing  20 . The cylindrical wall  50  also has an inner surface  51 , which forms a cylinder block cavity  56  forward of the suction  52  and discharge  54  chambers. 
     An outer surface  58 , of the cylindrical wall  50 , includes a threaded portion  60  around its circumference, near the forward end, and a cylindrical sealing portion  62  forward of the threaded portion  60 . The cylindrical sealing portion  62  slides within the inner surface  32  of the front housing portion  22 , with minimal clearance between  30  them. The cylindrical sealing portion  62  includes a recess that receives a third O-ring seal  64 , which seals against the inner surface  32 . Also, the inner surface  51  of the cylindrical wall  50  seals against the second O-ring  42 , since the rearward outer surface  40  of the cylinder block  23  fits within the cylinder block cavity  56  with minimal clearance. Of course, even though the rear housing portion  21  is shown sliding within the front housing portion  22 , the design of the joint configuration can be reversed, with the front housing portion having a smaller diameter outer surface that slides within the rear housing portion. Also, the front and rear housing portions and cylinder block can have locating pins and corresponding holes to assist with maintaining the orientation of the parts during assembly. 
     The valve plate assembly  27  mounts between the cylinder block  23  and the rear housing portion  21 . It has a valve retainer  66  mounted to it with bolts  68 . 
     The ring clamp  31  is a generally cylindrical member with a forward set of internal threads  84 , a rearward set of internal threads  86 , and a small circular wall  88  between them. The forward set of threads  84  are configured to mate with the external threads  30  on the front housing portion  22 , an the rearward set of threads  86  are configured to mate with the external threads  60  on the rear housing portion  21 . The orientation of the threads are such that, when the clamp  31  is turned in a first direction, the external threads  30  on the front housing  22  and the external threads  60  on the rear housing  21  will pull the two housing portions  21 ,  22  towards each other, and when the clamp  31  is turned in the opposite direction, the two housing portions  21 ,  22  will be pushed apart. The thread sets can be opposing or in the same direction, so long as the rotation in a first direction will pull the housing portions  21 ,  22  together. A set of grips  90  are spaced around the outer surface of the clamp  31 . The grips  90  allow for adequate engagement with the clamp  31  when turning with the appropriate torque, to assure that the desired clamp load is applied between the assembled portions of the housing assembly  20 . 
     After assembly to the desired torque, a locking hole is then drilled through the clamp  31  and a short distance into the rear housing portion  21 . A locking pin  92  is inserted into the locking hole to assure that the clamp  31  cannot work its way loose over time. In the alternative, a keyway or other locking mechanism may be employed to retain the clamp  31  in the desired position. 
     FIG. 6 illustrates a second embodiment of the present invention. In this embodiment, elements that are the same as in the first embodiment will be designated with the same element numbers, but those that have changed or been added will be designated with  100  series numbers. The valve plate assembly  27  and the cylinder block  123  mount within the forward housing portion  122  and the rearward housing portion  121 . The clamp  131  is slid over the outer surface  158  of the rear housing  121  until a shoulder  186  on the clamp  131  abuts a shoulder  160  on the rear housing  121 . The threads  30  on the forward housing  122  are engaged with the forward threads  84  on the clamp  131 . The clamp  131  is then turned, pulling the front  122  and rear  121  housings together until the desired clamping force is achieved. 
     Of course, O-ring seals (not illustrated in FIG. 6) can be located similar to those in the first embodiment to assure the proper sealing of the housing assembly  120 . Also, the configuration can be reversed so that the shoulder is on the front housing and the threads on the rear housing, if so desired. 
     While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.