Abstract:
A positive temperature coefficient of resistance resistor/overload (PTCR/OL) resistor assembly that can be quickly and easily electrically connected and disconnected from equipment without the need for special tools or equipment. In some arrangements of the present invention, a locking tab on the electrical connector can be secured against an angle on the PTCR/OL to prevent the electrical connection from being broken during shipping or operation equipment movement or vibration. When it is necessary to electrically disconnect the PTCR/OL from the equipment, the locking tab can be disengaged from the angle on the PTCR/OL by bending the tab until it releases from against the angle, and the electrical plug can then be disconnected from the PTCR/OL. The improved assembly provides increased isolation of incoming electrical wires with less material than previous devices. The improved assembly also provides for an easy method of using different terminals in the PTCR/OL, so that a variety of isolated electrical connectors can be utilized with the PTCR/OL with minimal modifications or changes.

Description:
BACKGROUND OF INVENTION  
         [0001]    Positive temperature coefficient of resistance resistor/overload (PTCR/OL) assemblies have many uses in industry. The resistance of PTCR/OL assemblies increases with a rise in temperature of the device. Essentially, these assemblies operate normally under normal temperature or electrical current conditions. However, when the ambient temperature in the assemblies or the current flow through the assemblies increases to a level where heat is produced, the resistance of the assemblies increases to limit the flow of current. PTCR/OL assemblies have numerous uses in electronic circuit boards and larger commercial and consumer equipment, such as relays, generators, motors and compressors.  
           [0002]    It is desirable to simplify the manufacture of these assemblies and their installation on the equipment of which they comprise a part. Because the equipment in which PTCR/OL assemblies are used is often bulky and heavy, it may be difficult to install the PTCR/OL assembly onto the equipment during manufacture due to size and location restraints. Similarly, removing a failed PTCR/OL assembly and installing a new assembly in situ is often hampered by equipment size and location and the position of the PTCR/OL assembly on the equipment. Thus, the need arose for PTCR/OL assemblies that could be easily installed during equipment manufacture, and easily replaced in situ in the event of a failure.  
           [0003]    Because the equipment on which PTCR/OL assemblies are used tend to be subject to vibration, designs have evolved that ensure the assemblies remain securely attached to the equipment, and that connection mechanisms remain securely connected during use, and will not vibrate loose over time. For electrical connections, there is a dual need of making a connection that will remain secure, and keeping electrical connections sufficiently isolated to prevent undesirable contact or short-circuit during operation due to equipment vibration. In order to achieve these operational objectives of ensuring secure connections and proper electrical contact, the electrical connection mechanisms designed are often difficult to install, remove, or reconnect when assembling or replacing the PTCR/OL assembly, and may require the use of special tools.  
         SUMMARY OF INVENTION  
         [0004]    One aspect of the present invention, accordingly, provides a PTCR/OL assembly which has an electrical connection that can be easily connected, disconnected, and reconnected, but which is secure enough to prevent disconnection of the electrical connection from the PTCR/OL assembly due to vibration or movement of the mechanism during operation, and which will keep the electrical connections properly isolated during operation.  
           [0005]    Another aspect of the present invention provides a method for electrically connecting a PTCR/OL assembly to the equipment with which it is used. The method includes providing an electrical connection that can be secured on the PTCR/OL assembly during operation to prevent disconnection of the electrical connection during shipping or operation, but which can be disconnected without the need for special tools in order to remove the PTCR/OL when desired.  
           [0006]    Another aspect of the present invention provides a PTCR/OL assembly with a PTCR/OL device that has an angle protruding out from the side for use in securing certain types of electrical plugs, the PTCR/OL having at least one male conductive terminal in a socket, each terminal being connected to a terminal plate, and an electrically isolated plug having a female conductive element for connecting to each male conductive terminal on the PTCR/OL, and one female wire receptacle for each female conductive element for connecting a wire capable of conducting electrical current.  
           [0007]    Yet another aspect of the present invention provides a method for connecting a PTCR/OL device to electrically conductive wire, the PTCR/OL having an angle protruding outwardly from the body in a plane parallel to the top of the device, adjacent to the at least one socket in the PTCR/OL. A male conductive terminal protrudes into each socket, the terminal connected to a terminal plate in the PTCR/OL. A plug assembly with at least one electrically isolated female conductive element is inserted into the at least one socket on the PTCR/OL such that the at least one female conductive element on the plug assembly is fittingly engaged on the corresponding male conductive terminal in the socket. At least one electrically conductive wire is inserted into each electrically isolated female wire receptacle in the plug to connect the PTCR/OL device.  
           [0008]    Additionally, because the PTCR/OL assembly is used with various pieces of equipment that use different types of electrical connectors, another aspect of the present invention is that with only minor modifications which can be made easily during manufacture, it is possible to configure various models of PTCR/OL such that they can be connected to numerous pieces of equipment, making it easier to manufacture a different PTCR/OL for each customer requirement. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0009]    For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:  
         [0010]    [0010]FIG. 1 is a partially exploded view of a PTCR/OL assembly embodying features of the prior art;  
         [0011]    [0011]FIG. 2 is an assembled view of a PTCR/OL assembly embodying features of the prior art;  
         [0012]    [0012]FIG. 3 is a partially exploded view of a PTCR/OL assembly embodying features of one arrangement of the present invention;  
         [0013]    [0013]FIG. 4 is an assembled view of a PTCR/OL assembly embodying features of one arrangement of the present invention;  
         [0014]    [0014]FIG. 5 is a detailed view of a locking tab plug of one arrangement of the present invention;  
         [0015]    [0015]FIG. 6 is a partially exploded view of a PTCR/OL assembly embodying features of another arrangement of the present invention;  
         [0016]    [0016]FIG. 7 is a detailed partially exploded view of an electrically isolated electrical plug of an arrangement of the present invention;  
         [0017]    [0017]FIG. 8 is a top view of a PTCR/OL device of one arrangement of the present invention;  
         [0018]    [0018]FIG. 9 is a top view of one arrangement of a PTCR/OL of the present invention with the cover removed, showing part of the mechanism of the present invention, including the terminals, plate, and pressure plates;  
         [0019]    [0019]FIG. 10 is a perspective view of the neutral terminal and pressure plate of the prior art;  
         [0020]    [0020]FIG. 11 is a perspective view of the neutral terminal and pressure plate of the prior art modified for use with the present invention; and  
         [0021]    [0021]FIG. 12 is an exploded view of some arrangements of the neutral terminals and pressure plate of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0022]    In the discussion of the FIGURES, the same reference numerals will be used throughout to refer to the same or similar components. In the interest of conciseness, various other components known to the art, such as compressors, generators, relays, and the like on which PCTR/OL assemblies are commonly used, have not been shown or discussed, except insofar as necessary to describe the present invention.  
         [0023]    In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be obvious to those skilled in the art that the present invention may be practiced without such specific details.  
         [0024]    Referring to FIGS. 1 and 2 of the drawings, the reference numeral  100  generally designates a PTCR/OL assembly embodying features of the prior art. The PTCR/OL assembly  100  comprises a PTCR/OL  102 , a plug-in run capacitor  108 , lead wires  104 ,  106 , and locking mechanisms  104   a ,  106   a  on the lead wires  104 ,  106 . The locking mechanisms  104   a ,  106   a , are required to prevent the lead wires  104 ,  106  from disconnecting, or vibrating loose from the terminals  114 ,  116  in the PTCR/OL  102  during operation of the equipment. As can be seen in FIG. 2, there are relatively deep wells  110 ,  112  that are used to insulate and isolate each of the lead wires  104 ,  106  and terminals  114 ,  116  in the PTCR/OL  102 , onto which the positive and negative locking mechanisms  104   a ,  106   a  are connected. The locking mechanisms  104   a ,  106   a  must be properly oriented in the wells  110 ,  112 , to be connected to the terminals. This orientation can be difficult to determine given the relative depth of the wells, which are required to electrically isolate the connections. Additionally, a special tool or small screwdriver must be inserted into the wells  110 ,  112  to actually connect or disconnect the locking mechanisms  104   a ,  106   a  from the terminals  114 ,  116  in the wells  110 ,  112  in order to remove or replace the device. This process is often complicated by confined physical locations of equipment and the position of the PTCR/OL assembly  100  on the equipment. Often, the size and bulk of the capacitor  108  makes access to the wells  110 ,  112  difficult, depending on the orientation of the PTCR/OL assembly  100  in situ.  
         [0025]    In FIG. 3, one embodiment of the present invention is shown which permits easy electrical connection or disconnection of the PTCR/OL assembly without the need for special tools. The reference numeral  200  generally designates a PTCR/OL assembly embodying features of the present invention. The PTCR/OL assembly  200  comprises a PTCR/OL  202 , and an electrical connection. Some arrangements of the PTCR/OL assembly  200  also comprise a plug-in run capacitor  208 . In the arrangement of the present invention shown in FIG. 3, the electrical connection comprises a locking-tab electrical plug  204  with lead wires  206  attached thereto. The plug  204  depicted in FIG. 3 is a commercially available plug comprising female connections into which the lead wires  206  are attached to make a secure electrical connection, female terminals for securing to the male electrical terminals on the PTCR/OL  202 , and an inward-facing locking tab  214  on an attached, flexible arm that snaps in place and locks under an angle  218  on cover  216  of the PTCR/OL  202 . It is understood that other types of commercially available plugs  204  can also be used with the PTCR/OL assembly  200  of the present invention. The PTCR/OL  202  has sockets  210 ,  212  into which the electrical plug  204  is inserted. Each socket  210 ,  212  contains a knife-blade type male electrical terminal  220 ,  222  onto which the female terminals of the plug  204  are connected. Because the plug  204  offers isolation of each of the wires  206 , the deep wells  110 ,  112  required for isolation of individual wires  104 ,  106  in the prior art are no longer necessary. Therefore, the sockets  210 ,  212  of the present invention are much shallower than the wells used in the prior art.  
         [0026]    As can be clearly seen in FIGS. 4 and 5, the size of the electrical plug  204  in one embodiment of the present invention is such that when the plug  204  is secured into the sockets  210 ,  212  on the PTCR/OL  202 , the locking tab  214  on the plug  204  rests under and against the angle  218  that projects from the side of the PTCR/OL  202 , as shown in FIG. 3. Because the arm on which the locking tab  214  is located is relatively thin, when the plug  204  is snapped in place, the arm flexes enough that the locking tab slides across the upper surface and along the side of the angle  218  on the PTCR/OL  202 , and snaps in place against the underside of the angle  218 . This secures the plug  204  onto the terminals  220 ,  222  on the PTCR/OL  202  such that the plug  204  will not vibrate loose from the PTCR/OL  202  during operation of the equipment on which the PTCR/OL assembly  200  is installed.  
         [0027]    When it is desired to electrically disconnect the PTCR/OL assembly  200  from the equipment, the locking tab  214  can be unlocked by flexing the arm into which the locking tab  214  is incorporated until the locking tab  214  is released from under the angle  218  on the PTCR/OL  202 . By pulling the plug  204  fully away from the PTCR/OL  202 , the electrical connection can be disconnected. In order to electrically reconnect the PTCR/OL assembly  200  to the equipment, the plug  204  should be aligned with the sockets  210 ,  212 , and the locking tab  214  aligned with the angle  218  on the PTCR/OL  202 . The plug  204  should be pushed into the sockets  210 ,  212  until the locking tab  214  snaps into place under the angle  218  and the female connections on the plug  204  are securely connected to the terminals  220 ,  222  on the PTCR/OL  202 . In addition to requiring only a single step, no special tools are required to electrically connect or disconnect the plug  204  and attached wires  206  from the PTCR/OL  202 . Also, because deep wells are not required to ensure electrical isolation during operation due to the fact that the plug  204  offers an extra degree of electrical isolation not seen in the old individual wires  104 ,  106 , less material is required to manufacture the PTCR/OL  202 .  
         [0028]    In another embodiment of the present invention shown in FIG. 6, the electrical connection comprises individual isolated electrical plugs  230   a ,  232   a  with lead wires  230 ,  232  attached thereto. The isolated electrical plugs  230   a ,  232   a  depicted in FIG. 6 are commercially available electrically isolated plugs comprising female connections into which the lead wires are attached to make a secure electrical connection. The PTCR/OL  202  has sockets  210 ,  212  into which the isolated plugs  230   a ,  232   a  are inserted. Each socket  210 ,  212  contains a knife-blade type male electrical terminal  220 ,  222  onto which the female terminals of the isolated electrical plugs  230   a ,  232   a  are connected. Typically, to prevent the possibility of incorrect electrical connection, terminal  220  and electrical plug  230   a  for the lead wire  230  are of a different size and/or shape than terminal  222  and electrical plug  232   a  for the neutral wire  232 . Because the plugs  230   a ,  232   a  of the present invention offer isolation of each of the wires  230 ,  232 , the deep wells  110 ,  112  required for isolation of individual wires  104 ,  106  in the prior art are no longer necessary. Therefore, the sockets  210 ,  212  of the present invention are much shallower than the sockets used in the prior art. Many varieties of electrically isolated plugs are commercially available. FIG. 7 shows another of the many types of isolated electrical plugs  230   a ,  232   a  that can be used in the PTCR/OL assembly  200  of the present invention.  
         [0029]    As can be seen in more detail in FIG. 8, the angle  218  is located adjacent to the sockets  210 ,  212  on the PTCR/OL  202 , and projects beyond the body of the PTCR/OL  202 . When the PTCR/OL  202  is connected to individual isolated electrical plugs,  230   a ,  232   a , rather than a plug  204  utilizing a locking tab  214 , the angle  218  may not be used, but is of a size and location so as to not interfere with the connection of the plugs  230   a ,  232   a . In one arrangement of the present invention, as shown in FIG. 8, the sockets  210 ,  212  on the PTCR/OL  202  are preferably not the same size as each other to further inhibit connecting the plug  204  or isolated electrical plugs  230   a ,  232   a  to the PTCR/OL  202  with an improper electrical orientation. This prevents any improper orientation of the wires, or reversal of the circuits, which could cause possible shorts or failures of the PTCR/OL assembly  200  or the device to which it is attached.  
         [0030]    As shown in FIG. 9, the cover  216  of the PTCR/OL  202  of the present invention has been removed. The terminals  220 ,  222  must be configured so that they project through the sockets  210 ,  212  in the cover  216  of the PTCR/OL  202 , as shown in FIG. 8. The lead terminal  220  must also be configured to connect to the plate  320  inside the PTCR/OL  202 . The neutral terminal  222  must be configured to connect to pressure plate  322  inside the PTCR/OL  202 . The pressure plate  322  connected to the neutral terminal  222  is configured to form a holder, along with an identical pressure plate  322   a  for the positive temperature coefficient (PTC) sensor  500 . Because the same pressure plate can be used for two parts within the PTCR/OL  202 , the number of parts to be manufactured, inspected and stocked for replacements is greatly reduced.  
         [0031]    The single piece pressure plate  322  and neutral terminal  114  used in the prior art is shown in detail in FIG. 10. However, the present invention utilizes a single PTCR/OL  200  that has neutral connection terminals  222  of varying shapes and sizes, depending on the particular arrangement used. One method of doing this is to make different plates  322  for each arrangement of PTCR/OL  200  developed. However, to reduce the cost and number of parts that must be manufactured, inspected and stocked, it was determined that it would be desirable to develop a single pressure plate  322  to which a variety of different types of connection terminals  222  could be attached. This was especially practical for the neutral terminal pressure plate  322 , because it already served a dual purpose as it existed in the PTCR/OL  200  to form the holder for the PTC sensor  500  when used with second pressure plate  322   a , and would have to continue to be manufactured in its present form. If the same pressure plate  322  could be used in the present invention with a variety of electrical connection terminals  222  without necessitating extensive rework, great savings in cost and efficiency could be recognized.  
         [0032]    As shown in FIG. 11, a part usable in the present invention can be achieved by welding, soldering or otherwise attaching an electrical connection terminal  222  to the existing pressure plate  322 . The terminal  114  used in the prior art PTCR/OL  100  can be cut off before or after attaching the new terminal  222  to the pressure plate  322 . However, because the PTCR/OL  200  of the present invention has sockets  210 ,  212 , which are in slightly different positions than the wells  110 ,  112  of the prior art PTCR/OL  100 , in most cases it is not necessary to cut off the terminal  114  used in the prior art PTCR/OL  100 . Because the terminal  222  is made separately and then attached to the pressure plate  322 , it can be made in a variety of different sizes, or of different conductive materials than the pressure plate  322 . FIG. 12 shows a pressure plate  322  and different shapes of terminals  222  which can be attached to the pressure plate  322 , depending on the application for which the PTCR/OL  200  will be used, and the electrical connection methods that will be employed. FIG. 12 depicts a pressure plate  322  from which the prior art terminal  114  has been removed.  
         [0033]    It is understood that the present invention can take many forms and embodiments. Having described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.