Patent Publication Number: US-6699078-B2

Title: Connector block having at least one protrusion, for a terminal assembly

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to connector blocks for terminal assemblies, and more particularly, to connector blocks for electrical conductor pins of hermetic terminal assemblies. 
     2. Description of Related Art 
     A hermetically sealed compressor, typically used for air conditioning or refrigeration applications, has a sealed metal chamber. A motor and a compressor are mounted within the chamber. The electrical power to the motor is connected through the chamber and a terminal assembly. 
     The terminal assembly typically takes the form of a cup-shaped metal support having three holes, sometimes referred to as the terminal cap. An electrical conductor pin is mounted in each of the three holes and is mechanically supported in the cup-shaped element by fused glass beads that are bonded to both the pin and the metallic element. The fused glass beads and the metal are connected to form a glass-to-metal seal. 
     Within the compressor, the three leads to the motor are terminated in connector clips each having a receptacle that slides down upon the pin. The three connector clips are mounted in a connector block having three parallel passageways through which the connector clips and leads pass. The connector clips are equiangularly arrayed in a position to be pushed upon the three pins of the terminal assembly, thereby forming the electrical connection between the motor and the electrical conductor pins. 
     During the operation of the compressor, metallic or degraded oil particles in the system are attracted to the surface of the fused glass beads. The buildup of such particles on the surface of the fused glass beads can establish an electrical conductive path resulting in a short circuit and/or a thermal failure. Other contaminants in the system, such as moisture and acidic components (e.g., halogen acids resulting from a partial decomposition of the halogenated hydrocarbon refrigerant), may also directly attack the glass surfaces causing or contributing to an electrical breakdown. Another cause of electrical breakdown of the terminal assembly pertains to compressor motor failure. As a result of the high temperatures during the compressor motor failure, carbon may be generated. Consequently, a mixture of the generated carbon may be deposited on the inside portion of the hermetic terminal assembly and form a conductive path between the terminal electrical conductor pins and ground, which may lead to arcing. 
     The present invention, which relates to connector block modifications, serves to minimize contaminants leakage in ambient surroundings and to minimize undesirable arcing, which, if combined with leakage contamination, could lead to destructive consequences. 
     Connector blocks for connecting lead wire ends to electrical conductor pins of a terminal assembly are known in the electrical connector art. For example, U.S. Pat. No. 4,059,325, issued to Edward A. Diminnie et al. on Nov. 22, 1977, proposes a flat shield facing the peripheral edge of a terminal cup sidewall. Another U.S. Pat. No. 4,966,559, issued to Ronald R. Wisner on Oct. 30, 1990, proposes a pin surrounding cylindrical side wall portion extending from a connector block face to fit snugly in interface contact within the open end of the terminal body member side wall. Yet another U.S. Pat. No. 5,129,843, issued to Benjamin Bowsky et al. on Jul. 14, 1992 and U.S. Pat. No. 5,131,858, issued to Henry H. Heimbrock on Jul. 21, 1992, both propose over-surface wall shield members in surrounding relation to conductor pin end portions. Another U.S. Pat. No. 5,580,282, issued to F. Dieter Paterek on Dec. 3, 1996, proposes an over-surface wall shield assembly of O-ring sealing members, extending from the outer face of a connector block configured to fit inside the terminal assembly and spacedly surround both the exposed pin assembly and pin insulation to provide tortuous passageways therebetween. 
     From the above patents, it can be seen that various attempts have been made in providing structure that shields conductor pins, as well as their insulating materials, from contaminants to minimize undesirable conductive arcing paths. For the most part, these past structures have been comparatively complex and costly in both manufacture and assembly and have fallen short of the results they have sought to achieve. They further present structural assembly, disassembly and wear problems. 
     The present invention, recognizing the limitations of past structures, provides a unique connector block for a terminal assembly which is straightforward, economical to manufacture, and easy to assemble and disassemble. 
     SUMMARY OF THE INVENTION 
     According to one exemplary aspect of the present invention, an apparatus and method are provided for a connector block adaptable to engage with a terminal assembly of a hermetically sealed compressor. The terminal assembly defines a cap and a number of electrical conductor pins extending from inside the cap. The connector block defines a substantially flat surface that has a number of holes adaptable to receive the electrical conductor pins. Around one or more of these holes there is employed a protrusion that at least partially surrounds the circumference of the hole. The substantially flat surface may have a circular construction. The substantially flat surface defines a connector lip erected around its perimeter. This connector lip is designed to cover the open-end portion of the cap of the terminal assembly and to surround the electrical conductor pins so as to minimize possible electrical arcing. 
     In another exemplary aspect of the present invention, the connector lip is further designed to seal the open-end portion of the cap of the terminal assembly such that the amount of particles from the hermetically sealed compressor that can enter into the cap of the terminal assembly is greatly minimized. 
     In yet another exemplary aspect of the present invention, the connector lip has an inside diameter that is slightly larger than the outside diameter of the open-end portion of the cap. 
     In a further exemplary aspect of the present invention, the connector lip has an inside diameter of approximately 1.322 inches and a height of 0.05 inch. In a still further exemplary aspect of the present invention, the connector lip and the connector block is one piece. 
     In another exemplary aspect of the present invention, at least one protrusion is further designed to surround at least a portion of an electrical conductor pin. In a still further exemplary aspect of the present invention, the protrusion and the connector block are one piece. 
     The present invention has many advantages over the prior art. For example, by covering the entire periphery of the terminal cap&#39;s open end, the amount of contaminants from the compressor chamber that is likely to enter the terminal cap may be significantly reduced. Moreover, the employment of one or more protrusions to at least partially surround the circumference of one or more of the holes of the connector block may further shield the electrical connector pins from contaminants and further reduce the possibility of damaging arcing. In fact, none of the prior art of reference discloses such protection for the terminal cap. At most, the prior art may propose a connector block that seals the terminal cap with O-rings attached to the outer face of the connector block. Nevertheless, the terminal cap&#39;s open end would still be left uncovered, rendering it vulnerable to the possibility of accumulation of contaminants. In addition, the connector block of the present invention can be manufactured more easily at much lower cost than the prior art&#39;s connector block that incorporates O-ring sealing members on its outer face. 
     Thus, a connector block in accordance with the present invention, which covers the entire periphery of the terminal cap&#39;s open end and employs at least one protrusion that at least partially surrounds the circumference of at least one of the holes of the connector block, has apparent advantages over the prior art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and advantages of the present invention will be best appreciated upon reference to the following detailed description and the accompanying drawings, in which: 
     FIG. 1 is a diagrammatic side view, partly in section, of the interior of a hermetically sealed compressor. 
     FIG.  2 A and FIG. 2B are rear perspective views of connector blocks in accordance with exemplary embodiments of the present invention. 
     FIG.  3 A and FIG. 3B are rear perspective views of the connector blocks illustrated in FIG.  2 A and FIG. 2B, respectively, adapted to couple with a terminal assembly. 
     FIG. 4 illustrates a rear elevation view of the connector blocks illustrated in FIG.  2 A and FIG. 2B, coupled with the terminal assembly. 
     FIG.  5 A and FIG. 5B are cross-sectional views of connector blocks in accordance with exemplary embodiments of the present invention. 
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
     The following description of embodiments in accordance with the present invention is directed to a connector block, which is adaptable to couple with a terminal assembly of a hermetically sealed compressor. Thus, specific details of the compressor, the terminal assembly, and the electrical connection between the motor and the terminal assembly are omitted. These structures are typical and well known in the compressor art. An example of a terminal assembly is shown in U.S. Pat. No. 5,580,282 which is fully incorporated herein by reference 
     Turning to the figures, FIG. 1 illustrates a hermetically sealed compressor which includes a sealed metal chamber  110 . A motor  120  connected to drive a compressor  130  are located within the sealed metal chamber  110 . Power to the motor  120  is typically applied to the three electrical conductor pins  70 , which will be discussed in detail later. An example of the applied power is a 220-volt, single-phase three-wire system. The terminal assembly  50 , best shown in FIGS. 3A,  3 B and  4 , is welded to the sealed metal chamber  110 . 
     FIG. 2A illustrates a front perspective view of a connector block  10  for a hermetically sealed compressor in accordance with the present invention. As shown in FIG. 2A, the connector block  10  includes a substantially flat surface  30 . FIG. 2A further illustrates three holes  40  in the center of the substantially flat surface  30 . A connector wall or lip  20  is erected around the perimeter of the substantially flat surface  30 . In this embodiment, the substantially flat surface  30  may have a circular construction. At least partially surrounding the circumference of at least one hole is a protrusion located on the substantially flat surface. As shown in FIG. 2A, there may be employed a protrusion  140  for each hole that fully surrounds the circumference of each hole  40  A protrusion  140  may take the form of a surface that is rounded and convex with respect to substantially flat surface  30 . In one embodiment, the protrusion will have a height of about 0.125 to 0.128 inches above the substantially flat surface, and a radius of about 0.188 to 0.191 inches, such that the intersection between the protrusion and the substantially flat surface defines a circle having a diameter of about 0.362 to 0.367 inches. 
     In another embodiment of the present invention, as shown in FIG. 2B, there may be employed a protrusion  141  that takes the form of a relatively thin cylindrical wall that fully surrounds the circumference of each hole. In one embodiment, the protrusion  141  will have a height of about 0.122 to 0.127 inches above the substantially flat surface. The protrusion may also have an inside diameter of about 0.160 inches, and an outside diameter of about 0.190 inches. 
     It will be understood by those of ordinary skill in the art with the benefit of this disclosure that other shapes for one or more protrusions may be employed. For example, a protrusion may take the form of a more conical, volcano-shaped structure having a relatively narrow top portion and a relatively broad base interfacing with the substantially flat surface. It will also be understood that one or more of the holes  40  of the connector block  10  may be key shaped, rather than circular. In this case, a protrusion of the present invention may accordingly be adapted to surround at least a portion of a key shaped hole. In one embodiment, the three holes  40  are equiangularly spaced from each other. 
     The connector block of the present invention is adapted to engage with a terminal assembly  50  as shown in FIGS. 3A and 3B. FIGS. 3A and 3B illustrate that the terminal assembly  50  may include a cap  60  and three electrical conductor pins  70 , which are adaptable to mate with the three holes  40  in the center of the substantially flat surface  30  of the connector block  10 . For that reason, the three holes  40  are spaced and aligned with the three electrical conductor pins  70 . Each electrical conductor pin  70  is mounted through the cap  60  such that a portion of the conductor pin  70  is shown on each side of the cap  60 . Each electrical conductor pin  70  is mounted inside the cap  60  by means of fused glass beads (not shown). The fused glass beads are sealed around the electrical conductor pins  70  and are sealed to the inside portion of the cap  60 . It is to be understood that the shape and number of holes can be varied in accordance with the terminal assembly electrical conductor pins with which they are to be associated. 
     The connector lip  20 , as shown in FIGS. 2A and 2B, is designed to engage with the open-end portion  80  of the terminal cap  60 . When the connector block  10  engages with the terminal assembly  50 , the connector lip  20  completely covers the terminal cap&#39;s open-end portion  80 . In one embodiment, the connector lip  20  overlaps the terminal cap&#39;s open-end portion  80 . In another embodiment, the connector lip  20  covers the entire terminal cap  60 . Nevertheless, the terminal cap&#39;s open-end portion  80  is covered in such a way that the cap&#39;s open-end portion  80  is sealed by the lip  20 . As the connector lip  20  seals the terminal cap&#39;s open-end portion  80 , the lip  20  also surrounds the electrical conductor pins  70  that are mounted inside the terminal cap  60 . As a result, the amount of particles or contaminants from the hermetically sealed compressor chamber that could enter into the terminal cap  60  is significantly reduced. Accordingly, the likelihood that an arc will jump from one electrical conductor pin to another pin or to other portions of the cap  60  where the contaminants have accumulated is thereby minimized. 
     In one embodiment, the inside diameter of the connector lip  20  is slightly larger than the outside diameter of the terminal cap&#39;s open-end portion  80 . For example, the connector lip  20  may have a diameter of 1.322 inches. In another embodiment, the connector lip  20  has a height of 0.05 inch. In another embodiment, the connector lip  20  may have a diameter of about 1.290 to 1.310 inches, and a height of about 0.122 to 0.127 inches, or a height of about 0.125 to 0.128 inches. Moreover, the connector lip  20  may either be separable from the connector block  10  or integral with the connector block  10 . 
     The connector block  10  may be formed using an injection molding technique. The connector block  10  may also be made from any one of a number of known plastic compounds having insulative properties. More specifically, the connector block  10  may be made from either ceramic, various polymeric materials, such as polypropylene, or anything that would be amenable to keeping the contaminants outside of the cap  60 . 
     As shown in FIG. 3A, FIG.  3 B and FIG. 4, the connector block  10  may also include three longitudinally extending separately spaced parallel passageways  90 . These passageways  90  are designed to accommodate lead wires  100 , which at one end are electrically connectable to the electrical conductor pins  70  through one end of the connector block  10 , i.e., the three holes  40  in the center of the substantially flat surface  30 . The other end of the lead wires  100  are electrically connectable to the motor  120  through the other end of the connector block  10 . The lead wires  100  can be selected from any lead wires known in the electrical art. 
     Clips (not shown) are attached at the ends of the lead wires  100 , which are connectable to the electrical conductor pins  70 . The clips are aligned with those holes  40  so that when the connector block  10  is pushed upon the electrical conductor pins  70 , the pins  70  will enter the clips and make electrical connection therewith and thereby connecting the motor  120  to the power supply (not shown) connected to the outside of the terminal assembly  50 . 
     FIG. 5A is a cross-sectional view of an exemplary connector block  10  according to the present invention, coupled with a terminal assembly  50 . Protrusion  140  is rounded and convex with respect to the substantially flat surface of the connector block. Electrical conductor pins  70  are mechanically supported within cap  60  by fused glass  150 . Protrusion  140  acts to shield at least a portion of the exposed portion of electrical pin  70 . The top most portion of protrusion  140  may extend above the exposed portion of electrical pin  70 , but it need not do so order to obtain the benefit of the present invention. In one embodiment, the top most portion of protrusion  140  may actually touch and seal against the fused glass  150  portion of the terminal assembly  50 . 
     FIG. 5B is a cross-sectional view of another exemplary connector block  10  according to the present invention, coupled with a terminal assembly  50 . In this exemplary connector block, protrusion  141  is a relatively thin cylindrical wall that fully surrounds the circumference of each hole. Similarly, protrusion  141  acts to shield at least a portion of the exposed portion of electrical pin  70 . The top most portion of protrusion  141  may extend above the exposed portion of electrical pin  70 , but it need not do so order to obtain the benefit of the present invention. In one embodiment, the top most portion of protrusion  141  may actually touch and seal against the fused glass  150  portion of the terminal assembly  50 . 
     It is to be understood that the connector block in accordance of the present invention can be efficiently and effectively used to engage with other types of terminal assemblies or other pin configurations. It further is to be understood that the present invention is not limited for use only with three electrical conductor pins. Rather, it is adaptable for use with one, two or any number of electrical conductor pins. 
     The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown. It is therefore evident that the particular embodiments disclosed above might be altered or modified and all such variations are considered within the scope and spirit of the invention.