Abstract:
A compressor ( 20 ) has a housing ( 22 ) having first ( 52 ) and second ( 48 ) members. A motor ( 24 ) within the housing ( 22 ) is coupled to one or more working elements ( 26, 28 ) to drive the one or more working elements ( 26, 28 ) to compress a fluid. A number of electrical terminals ( 104 ) are each mounted in an associated aperture ( 132 ) in the second housing member ( 48 ) and electrically connected to the motor ( 24 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to compressors. More particularly, the invention relates to hermetic refrigerant compressors. 
     Screw-type compressors are commonly used in air conditioning and refrigeration applications. In such a compressor, intermeshed male and female lobed rotors or screws are rotated about their axes to pump the working fluid (refrigerant) from a low pressure inlet end to a high pressure outlet end. During rotation, sequential lobes of the male rotor serve as pistons driving refrigerant downstream and compressing it within the space between an adjacent pair of female rotor lobes and the housing. Likewise sequential lobes of the female rotor produce compression of refrigerant within a space between an adjacent pair of male rotor lobes and the housing. The interlobe spaces of the male and female rotors in which compression occurs form compression pockets (alternatively described as male and female portions of a common compression pocket joined at a mesh zone). In one implementation, the male rotor is coaxial with an electric driving motor and is supported by bearings on inlet and outlet sides of its lobed working portion. There may be multiple female rotors engaged to a given male rotor or vice versa. 
     When one of the interlobe spaces is exposed to an inlet port, the refrigerant enters the space essentially at suction pressure. As the rotors continue to rotate, at some point during the rotation the space is no longer in communication with the inlet port and the flow of refrigerant to the space is cut off. After the inlet port is closed, the refrigerant is compressed as the rotors continue to rotate. At some point during the rotation, each space intersects the associated outlet port and the closed compression process terminates. 
     Many such compressors are hermetic compressors wherein the motor is located within the compressor housing and may be exposed to a flow of refrigerant. Hermetic compressors present difficulties regarding their wiring. Routing of conductors through the housing while maintaining hermeticity and convenience of use while controlling manufacturing costs present difficulty. One exemplary configuration involves mounting electrical power terminals on a machined terminal plate. The terminal plate is, in turn, mounted over an opening in the compressor housing and sealed thereto. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, a compressor has a housing having first and second members. A motor within the housing is coupled to one or more working elements to drive the one or more working elements to compress a fluid. A number of electrical terminals are each mounted in an associated aperture in the second housing member and electrically coupled to the motor. 
     In various implementations, the compressor may be a hermetic screw compressor. The first housing member may be a motor case having a compressor inlet port. The second housing member may be a rotor case. 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal sectional view of a compressor. 
         FIG. 2  is a view of a rotor case of the compressor of  FIG. 1  carrying a motor and an electrical terminal array. 
         FIG. 3  is a top view of the case of  FIG. 2 , partially cutaway along line  3 - 3  of  FIG. 2 . 
         FIG. 4  is a suction end view of the case of  FIG. 2 . 
         FIG. 5  is an enlarged view of the cutaway portion of  FIG. 3 . 
     
    
    
     Like reference numbers and designations in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
       FIG. 1  shows a compressor  20  having a housing assembly  22  containing a motor  24  driving rotors  26  and  28  having respective central longitudinal axes  500  and  502 . In the exemplary embodiment, the rotor  26  has a male lobed body or working portion  30  extending between a first end  31  and a second end  32 . The working portion  30  is enmeshed with a female lobed body or working portion  34  of the female rotor  28 . The working portion  34  has a first end  35  and a second end  36 . Each rotor includes shaft portions (e.g., stubs  39 ,  40 ,  41 , and  42  unitarily formed with the associated working portion) extending from the first and second ends of the associated working portion. Each of these shaft stubs is mounted to the housing by one or more bearing assemblies  44  for rotation about the associated rotor axis. 
     In the exemplary embodiment, the motor is an electric motor having a rotor and a stator. One of the shaft stubs of one of the rotors  26  and  28  may be coupled to the motor&#39;s rotor so as to permit the motor to drive that rotor about its axis. When so driven in an operative first direction about the axis, the rotor drives the other rotor in an opposite second direction. The exemplary housing assembly  22  includes a rotor housing  48  having an upstream/inlet end face  49  approximately midway along the motor length and a downstream/discharge end face  50  essentially coplanar with the rotor body ends  32  and  36 . Many other configurations are possible. 
     The exemplary housing assembly  22  further comprises a motor/inlet housing  52  having a compressor inlet/suction port  53  at an upstream end and having a downstream face  54  mounted to the rotor housing downstream face (e.g., by bolts through both housing pieces). The assembly  22  further includes an outlet/discharge housing  56  having an upstream face  57  mounted to the rotor housing downstream face and having an outlet/discharge port  58 . The exemplary rotor housing, motor/inlet housing, and outlet housing  56  may each be formed as castings subject to further finish machining. 
     Surfaces of the housing assembly  22  combine with the enmeshed rotor bodies  30  and  34  to define inlet and outlet ports to compression pockets compressing and driving a refrigerant flow  504  from a suction (inlet) plenum  60  to a discharge (outlet) plenum  62  (located below the cut plane and thus schematically indicated). A series of pairs of male and female compression pockets are formed by the housing assembly  22 , male rotor body  30  and female rotor body  34 . Each compression pocket is bounded by external surfaces of enmeshed rotors, by portions of cylindrical surfaces of male and female rotor bore surfaces in the rotor case and continuations thereof along a slide valve, and portions of face  57 . 
     The exemplary compressor is a hermetic compressor wherein the motor  24  is sealed within the housing  22  and exposed to the refrigerant passing through the compressor. The motor  24  is coaxial with the rotor  26  along the axis  500  and has a stator  100  and a rotor  102 . The rotor  102  is secured to an end portion of the shaft stub  39  to transmit rotation to the rotor  26 . To supply power to the motor, electrical conductors must pass through the housing. These may include a number of terminals  104  mounted in the housing. Exemplary terminals have exterior pin-like contacts  106  having axes  510 . Exemplary terminals  104  have interior contacts  108  (e.g., screw fittings). For each terminal, a wire  110  extends from a first end at the contact  108  to a second end at the motor. For an exemplary three-phase motor, there are three pairs of such terminals ( FIG. 2 ).  FIG. 2  shows the terminals in an exemplary arrangement as a parallel linear array with outboard portions extending from a flat face (outer surface portion)  120  of an integral terminal plate  122  of the rotor case  48 . 
       FIG. 3  shows further details of the terminal mounting. Each terminal is sealed by an elastomeric O-ring  130  compressed within a bore  132  in the plate  122 . Along the housing interior surface  134  there is a counterbore  136 . An interior insulator  140  has a main portion  141  ( FIG. 5 ) accommodated in the counterbore  136 . An exterior insulator  142  has a main body  143  atop the face  120 . The insulators  140  and  142  have respective insertion portions  144  and  145  within the bore  133  and having distal end faces sandwiching and compressively engaging the O-ring  130 . Compression is maintained by a nut  146  threaded to the pin  106  and bearing against the insulator body  143 . A head  147  of the pin may be faceted and captured by a head  148  of the insulator  140  and may receive the screw contact  108 . 
     In the exemplary embodiment, the face  120  and plate  122  fall along a local shoulder  150  ( FIG. 3 ) between a flange  152  and a local recessed area  154 . The flange  152  acts as a mounting flange along the surface  49  and receives bolts  154  ( FIG. 1 ) securing the motor case  52  to the rotor case  48 . Along the terminal plate  122 , the shoulder is off-longitudinal by an angle θ. Thus, the axis  510  is off-longitudinal by θ&#39;s complement. Exemplary θ is 45°, more broadly 30-60°. This angling facilitates a number of advantages. It permits ease in forming the rotor housing by casting. The rotor housing precursor may be cast (e.g., of iron or aluminum) and subject to further machining. The machining may include machining of the rotor bores  160  and  162  and the slide valve bore  164 . The machining may include forming various mounting holes and fluid communication passageways. The machining may include machining of the face  120  for precise planarity. The machining may include machining the bores  132  through the face  120  of the terminal plate  122 . 
     However, for the terminals, the machining includes machining of the counterbores  136  ( FIG. 4 ) with a tool inserted through the open upstream/suction side end (either before or after machining the face  49  thereon). The machining may also include machining a flat plateau surface  168  surrounding the group of bores  132  and counterbores  136  (e.g., before machining at least the counterbores). The angling helps provide clearance for the tools doing the internal machining. As viewed in  FIG. 4 , clearance is relative to a portion of the mounting flange to the left and upper and lower wall segments of a stator bore to the right, both extending to the face  49 . The stator bore retains a downstream portion of the stator to ensure coaxiality with the rotor  26 . The counterboring provides a counterbore base surface at a precise and consistent separation T from the face  120 . This permits precise positioning of the terminals. This also avoids sealing problems associated with mounting the terminals in a plate separate from the casting and which must be sealed thereto by additional means. The angling may provide additional use benefits. For example, as shown in  FIG. 3 , a major portion of the exposed pin lies inboard of the projection  520  of the perimeter  170  of the flange  152 . This may help reduce chances of damage to the pins. 
     The precision of the thickness T may provide additional assembly ease benefits. A precise amount of compression of the O-ring  130  is required to provide an effective seal. Typically this precision could be obtained by precise torquing. However, with a precise thickness T and precise lengths of the insulator insertion portions  144  and  145  less torque precision is needed. These dimensions may be chosen to provide the desired degree of O-ring compression when the underside (shoulder) of the insulator body  143  is flat against the face  120  and the underside of the body  141  is bottomed against the base of the counterbore. This eases assembly and reduces risk of damage to the O-ring from overtorquing. 
     An additional assembly benefit may come from radial enlargement and faceting of the heads  148 . The spacing between bores and the size of the heads  148  is chosen so that each head  148  interfits with the next so that more than a slight rotation of the head  148  brings it into interference with the adjacent head(s)  148  to prevent more than limited rotation. The antirotation engagement of the pin head  147  to the insulator head  148  thus holds the pin against more than this limited rotation. Thus, to tighten the nuts  146  no separate tool is necessarily required to hold the head of the pin. 
     One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, in a reengineering, details of the existing compressor configuration may particularly influence or dictate details of the implementation. Accordingly, other embodiments are within the scope of the following claims.