Patent Publication Number: US-2003234115-A1

Title: Hermetically sealed current conducting terminal assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     [0001] This application claims the benefit of U.S. Provisional Application No. 60/380,994 filed on May 16, 2002. The disclosure of the above application is incorporated herein by reference. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The present invention relates to hermetically sealed, current conducting terminal assemblies suitable for installation in an opening in the wall of a housing.  
       BACKGROUND OF THE INVENTION  
       [0003] It is known to provide a hermetically sealed, current conducting terminal assembly that can be installed in a housing to provide an electrical connection through a wall of the housing, while electrically isolating the terminal assembly from the housing. Such terminal assembly incorporates a current conducting terminal pin, the outer segment of the pin being connected to an electrical power source and the inner segment of the pin being hermetically confined within the housing and connected to a device within the housing, such as a sealed motor unit, for example.  
       [0004] As shown in FIG. 6, a plurality of terminal assemblies  10  are extending through a housing plate  12  and walled housing  14 . The housing plate  12  and walled housing  14  include a series of attachment apertures  16  and accompanying fasteners  18  for attaching the housing plate  12  to the walled housing  14 . In addition, the housing plate  12  and walled housing  14  include a plurality of coaxially aligned threaded bores  20  for mating engagement with the terminal assemblies  10 .  
       [0005] The terminal assemblies  10  are received by the threaded bores  20  of the housing plate  12  and walled housing  14 . One terminal assembly arrangement can be found in U.S. Pat. No. 5,227,587, issued on Jul. 13, 1993 to F. Dieter Paterek, the general arrangement being particularly adapted to hermetically sealed housings. As shown in FIG. 7, the hermetic terminal assembly  10  of Paterek includes an annular sleeve  26 , a hermetic seal  28 , a pair of insulating annular ceramic sleeves  30 , and a current conducting pin  32 . The annular sleeve  26  includes a series of threads  34  for attaching the terminal assembly  10  to a threaded bore  20  of a housing plate  12  or walled housing  14 . The current conducting pin  32  comprises a unitary body having a first threaded end  36  and a second threaded end  38 . The first threaded end  36  and second threaded end  38  are operable to connect to an external source generally disposed outside of the walled housing  14  and an internal source disposed within the walled housing  14 , respectively.  
       [0006] The hermetic seal  28  and annular ceramic sleeves  30  electrically isolate the current conducting pin  32  from the annular sleeve  26 . In this regard, the hermetic seal  28  and annular ceramic sleeves  30  allow the current conducting pin  32  to transmit electricity into and out of the walled housing  14  without transmitting electricity to the housing wall  40 .  
       [0007] The terminal assemblies described above may be comparatively expensive and difficult to manufacture. Therefore, a hermetically sealed terminal assembly that is easier and less expensive to manufacture while concurrently providing for the effective electrical isolation between a current conducting pin and a housing is desirable in the industry.  
       SUMMARY OF THE INVENTION  
       [0008] The invention provides a self-contained, hermetically sealed terminal assembly. The invention is suitable for installation in the wall of a housing or in a housing plate. The terminal assembly comprises a multi-component, current conducting pin assembly having a first pin member and a second pin member that are joined at a core. In at least some embodiments of the invention, the core physically and/or electrically connects the first and second pin members of the pin assembly. An annular sleeve is axially disposed around pin assembly. The pin assembly is fused to the annular sleeve by a glass-to-metal seal that provides a first electrically insulating hermetic seal between the pin assembly and the annular sleeve. In addition, first and second sleeves are disposed over the first and second pin members on opposite sides of the core to provide a second electrically insulating seal and oversurface protection between the pin assembly and the annular sleeve.  
       [0009] Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0010] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
     [0011]FIG. 1 is cross-sectional front view showing a terminal assembly installed in a housing, the terminal assembly comprising a pin assembly including first and second pin members and a core comprising a cylindrical collar and a stud portion having threaded extensions;  
     [0012]FIG. 2 is cross-sectional front view showing another embodiment of a terminal assembly comprising a pin assembly including first and second pin members and a core comprising a cylindrical collar portion and threaded extension portions having a unitary construction;  
     [0013]FIG. 3 is cross-sectional front view of another embodiment of a terminal assembly comprising a pin assembly including first and second pin members and a cylindrical collar comprising two internally threaded blind bores each for receiving one of the first and second pin members;  
     [0014]FIG. 4 is cross-sectional front view of a fourth embodiment of a terminal assembly including a pin assembly comprising first and second pin members and a cylindrical collar having a bore for receiving the first and second pin members; and  
     [0015]FIG. 5 is a cross-sectional front view of another embodiment a terminal assembly including a pin assembly comprising first and second pin members and a collar having a threaded through bore for receiving both the first and second pin members;  
     [0016]FIG. 6 is a perspective view of a housing plate and walled housing including a plurality of hermetically sealed, current conducting terminal assemblies; and  
     [0017]FIG. 7 is a terminal assembly having a current conducting pin of unitary construction. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0018] The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
     [0019] FIGS.  1  though  5  show various configurations of a hermetically sealed, current conducting pin installation  100 ,  200 ,  300 ,  400 ,  500  for mounting in a wall of a hermetically sealed housing  50 . The housing  50  can enclose a comparatively large size electric device demanding high operating voltages and currents, such as a compressor with a rating as high as three hundred ( 300 ) horsepower, for example. A control unit that conventionally demands lower current and voltage ratings may also be included (not shown) within the sealed housing  50 . The different power requirements for both the compressor and the control unit may be carried by hermetically sealed, current conducting pin installation  100 ,  200 ,  300 ,  400 ,  500 . It is to be understood that the several features of the present invention, although particularly suitable for sealed housings of larger type compressor and control units, are not to be considered as limited to the particular size and shape disclosed and, that such features can also be utilized with other devices, such as those with lower power requirements.  
     [0020] With particular reference to FIG. 1, a first embodiment of the hermetically sealed current conducting pin installation  100  is shown as including an annular sleeve  102 , a pin assembly  104 , a first electrical insulator and hermetic seal  106 , and a second electrical insulator  108 .  
     [0021] The annular sleeve  102  is a substantially cylindrical member having a bore  110 , an axial flange  112  at a first end, and a threaded portion having threads  114  adapted to matingly engage corresponding threads of a larger opening in a housing  50 . The junction of the threaded portion and the axial flange  112  cooperate to form an axial recess  116  where an O-ring  118  is disposed for engagement with an outer wall of the housing  50  to create a seal. While an O-ring  118  is disclosed, any suitable gasket could be used to adequately seal the outer surface of the housing wall and the axial flange  112  of the annular sleeve  102  and should be considered within the scope of the invention.  
     [0022] The pin assembly  104  includes a first longitudinal pin member  120  and a second longitudinal pin member  122 , each of which are formed from a current conducting material such as copper or brass. The first pin member  120  is substantially cylindrical and has a generally constant diameter along its length. The first member  120  includes a threaded portion  124  at a distal end  126  and a threaded bore  128  at a proximal end  130 .  
     [0023] The second pin member  122  is also substantially cylindrical and has a constant diameter along its length. The second pin member  122  similarly includes a threaded portion  132  at a distal end  134  and a bore  136  formed at a proximal end  138 . While the present invention discloses that the pin members  120 ,  122  are formed from stainless steel, it should be noted that any suitable conductive material may be used and should be considered within the scope of the present invention.  
     [0024] The pin assembly  104  also includes a core  140  that serves to physically join together and electrically connect the first and second longitudinal pin members  120 ,  122 . The core  140  includes a stainless steel tube or collar  142  and a central member or stud portion  144  formed from a conductive material such as, for example, copper. The collar  142  includes an inner surface  146  and an outer surface  148 . The outer surface  148  has a diameter that is generally the same as the diameter of the pin members  120 ,  122 . The collar  142  surrounds the stud  144  at its midpoint such that first and second extension portions  150 ,  152  of the stud  144  extend away from the collar  142  in opposite directions. The collar  142  is brazed to the stud  144  at the inner surface  146  to fixedly attach the collar  142  to the stud  144 .  
     [0025] The stud  144  has a generally cylindrical shape and is disposed between the first and second longitudinal pin members  120 ,  122 . The first extension portion  150  of the stud  144  is received in the bore  128  of the first pin member  120  and the second extension portion  152  of the stud  144  is received in the bore  136  of the second member  122 . The first and second longitudinal pin members  120 , 122  are joined together via the stud  144 .  
     [0026] The outer surface  148  of the collar  142  has a diameter that is generally equivalent to the diameter of the longitudinal pin members  120 ,  122 . Thus, the outer surface  148  of the collar  142  is generally flush with both the outer surface  154  of the first longitudinal pin member  120  and the outer surface  156  of the second longitudinal pin member  122 .  
     [0027] While the stud  144  described above is formed from copper, other conductive materials such as brass, for example, may be used and should be considered within the scope of the present invention.  
     [0028] The first insulator and seal  106  is disposed between the outer surface  148  of the collar  142  and an inner surface  158  of annular sleeve  102  to hermetically seal and electrically insulate the pin assembly  104  from the annular sleeve  102 . Insulator and seal  106  provides a hermetic seal  160  and may comprise a glass-to-metal seal that is well known to those in the art. The glass-to-metal seal may be fused to both the pin assembly  104  and inner surface  158  of the annular sleeve  102 .  
     [0029] The second insulator  108  comprises a pair of opposed, annular ceramic sleeves  162 ,  164  that surround the first and second longitudinal pin members  120 ,  122  of the pin assembly  104  at their respective proximal ends  130 ,  138 . The second insulator  108  provides oversurface protection for the pin members  120 ,  122  to further insulate the pin assembly  104  from both the annular sleeve  102  and the housing  50 . Each of the insulating sleeves  162 ,  164  is disposed in mirror-image relation to one another on opposite faces  166 ,  168  of the hermetic seal  160  and are so contoured that a lower extremity face  170 ,  172  of a smaller diameter portion  174 ,  176  of the insulating sleeves  162 ,  164  can be fused or epoxy glued to the faces  166 ,  168  of the hermetic seal  160 .  
     [0030] The smaller diameter portions  174 ,  176  of the insulating sleeves  162 ,  164  abut the inner surface  158  of externally threaded annular sleeve  102  on a first side  178  and abut the outer surfaces  154 ,  156  of the longitudinal pin members  120 ,  122  of the pin assembly  104  on a second side  180 . A larger diameter annular shoulder  182 ,  184  of each insulating sleeve  162 ,  164  is arranged to overlap the outer face extremities  186 ,  188  of the annular sleeve  102 .  
     [0031] As previously discussed, the first and second insulators  106 ,  108  are operable to electrically isolate the pin assembly  104  from the annular sleeve  102 . In this manner, the current conducting pin installation  100  may be attached to the housing  50  via the annular sleeve  102  and an electric current may pass through the pin assembly  104  between sides  52 ,  56  of a housing wall  54 .  
     [0032] With particular reference to FIG. 2, a second embodiment of the hermetically sealed current conducting pin installation  200  is shown having an annular sleeve  102 , first and second insulators  106 ,  108 , and a pin assembly  204 .  
     [0033] In general, the hermetically sealed current conducting pin installation  200  is substantially similar to the hermetically sealed current conducting pin installation  100  described above. In view of the substantial similarity in structure and function of the components associated with the hermetically sealed current conducting pin installation  100  and the hermetically sealed current conducting pin installation  200 , like reference numerals are used here and in the drawings to identify like components.  
     [0034] The pin assembly  204  of this embodiment comprises a core  240  having unitary construction, including a central cylindrical collar portion  244  and first and second extension portions or studs  250 ,  252 . The central collar portion  244  has an outer surface  248  that is generally equivalent to that of the pin members  120 ,  122 . The central collar portion  244  is attached to the first insulator and seal  106  along the outer surface  248 . The first and second extension portions  250 ,  252  are received in the first and second pin members  120 ,  122  of the pin assembly  204 , thereby joining the first and second members  120 ,  122  of the pin assembly  204  to the central collar portion  244 , as previously discussed.  
     [0035] With particular reference to FIG. 3, a third embodiment of the hermetically sealed current conducting pin installation  300  is shown having an annular sleeve  102 , a first and second insulators  106 ,  108 , and a pin assembly  304 .  
     [0036] The hermetically sealed current conducting pin installation  300  is substantially similar to the hermetically sealed current conducting pin installation  100  described above. In view of the substantial similarity in structure and function of the components associated with the hermetically sealed current conducting pin installation  100  and the hermetically sealed current conducting pin installation  300 , like reference numerals are used here and in the drawings to identify like components.  
     [0037] The pin assembly  300  has a core  340  comprising a cylindrical collar  341  that includes first and second blind threaded bores  390 ,  392  and an outer surface  348 . The outer surface  348  is generally the same in diameter as the diameters of pin members  320 ,  322  of the pin assembly  304 . The core  340  is attached to the first insulator and seal  106  generally at the outer surface  348  and serves to insulate the pin assembly  304  from the annular sleeve  102 .  
     [0038] The pin assembly  304  includes the first longitudinal pin member  320  and the second longitudinal pin member  322  which are physically joined together and electrically connected by the core  340 . The first pin member  320  includes a first cylindrical post  394  extending from its proximal end  330 . The post  394  includes external, male threads  393  for interaction with corresponding internal, female threads  395  in the core  340 . Similarly, the second pin member  322  includes a second cylindrical post  396  extending from its proximal end  338  having external, male threads  397  for interaction with corresponding internal female threads  399  in the core  340 . The first and second posts  394 ,  396  are received, respectively, in the first and second threaded bores  390 ,  392  of the core  340  such that both the first pin member  320  and the second pin member  322  are connected with the core  340 .  
     [0039] With particular reference to FIG. 4, a fourth embodiment of the hermetically sealed current conducting pin installation  400  is shown. Current conducting pin installation  400  is illustrated as having an annular sleeve  102 , first and second insulators  106 ,  108 , and a pin assembly  404 .  
     [0040] In general, the hermetically sealed current conducting pin installation  400  is substantially similar to the hermetically sealed current conducting pin installation  100  described above. In view of the substantial similarity in structure and function of the components associated with the hermetically sealed current conducting pin installation  100  and the hermetically sealed current conducting pin installation  400 , like reference numerals are used here and in the drawings to identify like components.  
     [0041] The pin assembly  404  includes a core  440 , a first pin member  420  and a second member  422 . The first and second pin members  420 ,  422  are operable to directly engage one another to become physically and electrically connected. Specifically, the first member  420  includes a frustum  401  formed at the proximal end  430  of a first cylindrical post  494  for mating engagement with a tapered bore  403  formed in a second cylindrical post  496  of the second member  422  where the second cylindrical post  496  is formed in the proximal end  438  of the second pin member  422 .  
     [0042] The core  440  surrounds the connection between the first and second posts  494 ,  496 . The core  440  comprises a stainless steel tube or collar  142  having an inner surface  146  and an outer surface  148 . The inner surface  146  engages outer surfaces  405 ,  407  of each of the first and second cylindrical posts  494 ,  496  and the outer surface  148  is attached to the first seal  106 . The collar  142  abuts the first and second members  420 ,  422  of the pin assembly  404  such that the outer surface  148  of the collar  142  and the outer surfaces  154 ,  156  of the first and second pin members  420 ,  422  are flush relative one another.  
     [0043] Referring now to FIG. 5, a fifth embodiment of the hermetically sealed current conducting pin installation  500  is shown. The hermetically sealed current conducting pin installation  500  is substantially similar to the hermetically sealed current conducting pin installation  100  described above. In view of the substantial similarity in structure and function of the components associated with the hermetically sealed current conducting pin installation  100  and the hermetically sealed current conducting pin installation  500 , like reference numerals are used here and in the drawings to identify like components.  
     [0044] The current conducting pin installation  500  is shown as comprising an annular sleeve  102 , a first insulator and seal  506 , a second insulator  108 , and a pin assembly  504 . The pin assembly  504  comprises a core  540 , a first pin member  520  and a second pin member  522 . The first member  520  includes a first extension  594  having external male threads  593  that are aligned adjacent to a second extension  596  of the second pin member  522 , which similarly includes external male threads  597 . The opposing end faces of the first and second extensions  594 ,  596  may be joined by a suitable method such as, but not limited to, brazing.  
     [0045] The core  540  surrounds the interface between the first and second posts  594 ,  596  and is operable to join the first and second members  520 ,  522  to the first insulator and seal  506 . The core  540  comprises a stainless steel tube or collar  542  having an inner surface  546  including a series of threads  509  for mating engagement with the first and second threads  593 ,  597  of the first and second cylindrical posts  594 ,  596 . In addition, the collar  542  includes an outer surface  148  for attachment to the first insulator and seal  506 . The collar  542  abuts the first and second pin members  520 ,  522  of the pin assembly  504  such that the outer surface  148  of the collar  542  and outer surfaces  154 ,  156  of the first and second members  520 ,  522  are flush relative one another.  
     [0046] The first seal  506  includes a central portion  511  formed from a suitable glass material flanked by a pair of epoxy layers  513 . The epoxy layers  513  serve to attach the central portion  511  of the first insulator and seal  506  to the outer surface  148  of the collar  542  and also to the smaller diameter portions  174 ,  176  of the second insulator  108  to ensure a constant seal between the pin assembly  504  and the first and second insulators  506 ,  108 .  
     [0047] From the above description, it can be seen that a hermetically sealed current conducting terminal assembly is provided for ready insertion and maintenance removal. Further, each embodiment provides a novel approach to construction of a hermetically sealed current conducting terminal assembly that provides for a reduction in manufacturing time, effort and cost.  
     [0048] The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.