Patent Publication Number: US-6210208-B1

Title: Quick connect terminal and terminal block

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     This invention relates to electrical connectors used to connect the heating element of a heating unit installed in a water heater or the like, and more particularly, to a quick connect terminal and terminal block which provides a simplified way of connecting electrical leads to the heating element, this being accomplished without the use of screwdrivers or similar type tools. 
     Heating units used in water heaters are well-known in the art. Conventional units include a screwplug which is screwed into a threaded opening in a sidewall of a water heater tank. The heating element has an elongate U-shape and extends well into the interior of the tank. Terminal ends of the heating element extend through the screwplug for electrical leads to be connected to the respective ends of the heating element. These connections have heretofore typically been made by soldering an end of the lead to an end of the heating element, by wrapping a portion of the lead about a screw and threading the screw into a threaded hole using a screwdriver, or by otherwise permanently connecting the two together. A drawback with these previous techniques is that they involve a great deal of manual labor which adds to the time and cost of completion of the assembly. 
     BRIEF SUMMARY OF THE INVENTION 
     Among the several objects of the present invention may be noted the provision of a resistance heating unit for use in a water heater, the heating unit being a screwplug type unit having a heating element with terminal ends which extend through the screwplug; 
     the provision of such a heating unit employing a new method of attaching the terminal ends of the heating element into an electrical circuit by which current is directed through the heating element to heat the water; 
     the provision of such a new method to include, in combination, a terminal quick connect and a terminal block in which the terminal quick connect is installed; 
     the provision of such a method to employ a separate quick connect for connecting each end of the heating element with an electrical lead, both quick connects being installed in the terminal block; 
     the provision of each terminal quick connect to separately engage an end of the heating element and the electrical lead to which the heating element connects; 
     the provision of each terminal quick connect to be of an electrically conductive material with the end of the heating element frictionally fitting into one portion of the quick connect, and the electrical lead being captured at another portion of the quick connect; 
     the provision of each terminal quick connect to include a slot in which the electrical lead is captured, the lead being readily and automatically inserrtable into the slot and not requiring manual labor to complete the electrical connection; 
     the provision of each terminal quick connect to permanently secure the end of the heating element and the electrical lead together; 
     the provision of the terminal block to be an electrically non-conductive material and to include provisions for separately securing each terminal disconnect in place and electrically isolated from each other so the terminations cannot short together; 
     the provision of such a terminal block in which the terminal quick connects are easily installed and from which they cannot be removed or dislodged; and, 
     the provision of such a new method of installation which simplifies manufacture of the heating unit, eliminates current manufacturing steps so to lower the manufactured cost of a heating unit, yet which provides a reliable heating unit which is readily installed in a water heater. 
     In accordance with the invention, generally stated, apparatus is provided which facilitates electrical connection of a heating element used in a water heater heating unit. The heating unit is a screwplug type unit having a body through which the ends of the heating element pass. A separate terminal quick connect frictionally engages each end of the heating element. The electrical lead which connects with the end of the heating element is separately engaged by the terminal quick connect so the end of the heating element is electrically connected in the circuit supplying power to the heating unit. A terminal block attaches to an outer face of the screwplug. The terminal block has a set of openings in it in which the terminal quick connects are received. The terminal quick connects each have a tab received in a slot formed in the terminal block to secure the terminal quick connects to the terminal block. Other objects and features will be in part apparent and in part pointed out hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     In the drawings, FIG. 1A is a simplified representation of a section of a water heater in which a screwplug type water heater is installed, and FIG. 1B illustrates a body portion of the screwplug with the ends of heating element extending through it; 
     FIG. 2 is an end view of the heater unit illustrating the apparatus of the present invention for electrically connecting the ends of the heating element into an electrical circuit; 
     FIGS. 3A,  3 B, and  3 C are respective top plan, side elevational, and end elevational views of a terminal block portion of the apparatus; 
     FIG. 4A is a top plan view of a terminal quick connect of the apparatus; and, 
     FIGS. 4B,  4 C, and  4 D are respective side elevational views of the terminal quick connect. 
    
    
     Corresponding reference characters indicate corresponding parts throughout the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, a heater unit  10  is for heating water W contained in a water heater tank T such as is well-known in the art. As shown in FIGS. 1A and 1B, heater  10  is a screwplug type unit having a body  12  and a heating element  14 . The heating element has an elongate U-shape, and the body has a threaded plug portion  12   a  for screwing the heater unit into a threaded bore in the water tank sidewall S. The outer end of the screwplug body has a flange section  12   b  which is of a hexagonal shape, for example. In FIG. 1B, the ends  14   a,    14   b  of the heating element are shown to extend through longitudinal bores B in the screwplug body and to project a distance past the flange end of the body. 
     Once installed, it is necessary to connect the heater unit into an electrical circuit by which power is supplied to the heating element. In the drawings, this circuit is represented by the electrical leads L 1 , L 2 . Heretofore, the leads have been connected to the ends of the heating element in various ways as is known to those skilled in the art. While these ways are not described, they all require the installer to use tools of some sort such as screwdrivers, or to solder the leads to the ends of the heating element. As noted above, this is a time consuming process which adds to the manufactured cost of the water tank. 
     The apparatus of the present invention is indicated generally  20  in FIG.  2 . As shown therein, and as described hereinafter, the apparatus first includes one, and preferably a pair of terminal quick connects indicated generally  22 . These units each frictionally engage one end  14   a  or  14   b  of heating element  14 . Further, each terminal quick connect unit separately engages one of the electrical leads to which an end of the heating element is electrically connected, thus connecting the heating element into the power circuit. In addition, apparatus  20  includes a terminal block  24  which is attached in any convenient manner to an outer surface  26  of the flange. As described hereinafter, the terminal quick connects are installed in and secured to the terminal block. 
     In FIGS. 4A-4D, one of the terminal quick connects  22  is shown. The other unit is identical to the one shown and will not be described. The terminal quick connect unit first includes a plate  32  made of an electrically conductive material. The plate is generally rectangular in plan. At one end  34  of the plate, the edges  36   a,    36   b  are chamfered as shown in FIG.  4 A. On the side of plate  32  inwardly of end  34  is formed a pair of opposed tabs  38   a,    38   b  for frictionally engaging one end of the heating element. These tabs are formed by a cutting operation in which two parallel slits  40  are cut into the top of plate  32 . These slits extend parallel to side  34  of the plate. Another slit extends perpendicular to the slits  40  and extends between these slits. Respective correspondingly formed notches  42   a,    42   b  are now made in abutting sides of the opposed tabs. These notches are V shaped notches and their size is such as to accommodate an end of the heating unit. Both of the tabs  38   a,    38   b  are bent outwardly away from the outer, flange end of the screwplug body when the apparatus is in place. The tabs extend outwardly from the plate at corresponding angles with respect to the plate. End  14   a  or  14   b  of the heating element extends through the opening formed by the notches from the underside of the plate. The tabs  38   a,    38   b  now frictionally engage this outer end of the heating element and prevent its withdrawal from engagement with the tabs. 
     Referring to FIG. 4A, a slot  50  is formed in plate  32 . Slot  50  extends into the body of plate  32  from one side  52  of the plate. A first reach  54  of the slot extends transversely of a longitudinal axis of the plate and substantially across the width of the plate. A second reach  56  and third reach  58  of the slot extend lengthwise of the plate (orthogonally of reach  54 ) in the direction of the tabs  38   a,    38   b.  As shown in the drawings, slot  50  defines an engagement tab  60  for engaging wire strands of a respective lead L so to electrically connect the lead to the plate. Reach  54  of slot  50  is formed adjacent one end  62  of plate  32 , end  62  being downwardly turned to form a sidewall for the plate. Further, as shown in FIG. 4A, a notch or recess  64  is formed in the sidewall. The notch is sized to accommodate the wire strands for the electrical lead. During assembly of the heater unit, the insulation is stripped from the end of the lead to expose the wire strands which are then pushed through slot  50 . As indicated in FIG. 4A, a line of weakness  66  allows engagement tab  60  to be depressed beneath the top surface of the plate. The angled surface of the engagement tab facilitates insertion of the lead into slot  50 . Once the wire strands are in place, the engagement tab can be pushed against them to secure the electrical lead to the terminal quick connect. It will be noted that no tools are required to attach the electrical lead to the terminal quick connect. This saves manufacturing time and cost. 
     On opposite side  66  of plate  32  from side  62 , a mounting tab  70  is formed. This mounting tab is used to attach terminal quick connect  22  to terminal block  24 . As best shown in FIG. 4D, mounting tab  70  is a spear shaped tab which is centered along the length of side  66  and depends below the lower end of sidewall  62  of the terminal quick connect. The tab extends outwardly from the side of the plate and tapers inwardly from the upper end of the tab to where the lower spear shaped end  72  of the tab is formed. 
     Referring to FIGS. 3A-3C, terminal block  24  has a generally rectangular base  82  with depending sidewalls  84 ,  86 , and endwalls  88 ,  90 . The corners of the terminal are each chamfered. The height of the sidewalls and endwalls are such that when mounted in place, the terminal quick connects do not touch outer face  26  of flange  12   b.  Plate  82  is divided in half by an upstanding, longitudinally extending wall  92 . The terminal block is of an integrally formed, one-piece construction and is made of a plastic or other suitable non-electrically conductive material. One terminal quick connect is mounted one side of the terminal block, and the other terminal quick connect on the other. Wall  92  not only provides a handle to make the terminal block easy to grip and hold, but also serves to electrically isolate the two terminal quick connects so the heating element cannot be shorted out at the ends of the heating element. 
     Referring to FIG. 3A, plate  82 , on each side of wall  92 , has three identical sets of openings. One set of openings  94   a,    94   b,  are circular openings sized for ends  14   a,    14   b  of heating element  14  to be inserted through the openings. This set of openings is generally formed such that opening  94   a  is slightly to one side of the center of the terminal block, and opening  94   b  is slightly to the other side of center. The next set of openings  96   a,    96   b  are oblong generally L-shaped openings which accommodate one end of a terminal quick connect  22 . One leg of the openings extends generally parallel to wall  92  and the other leg perpendicular of the wall, toward the wall. The opening  96   a  is toward one end of the terminal block, and the other opening is toward the opposite end of the terminal block. The openings are sized so end  62  of plate  32  is received in the opening, as is engagement tab  60 . Finally, a pair of slots  98   a,    98   b,  extend perpendicular to wall  92 . Slot  98   a  is formed on the opposite side of opening  94   a  from opening  96   a,  and slot  98   b  is on the opposite side of opening  94   b  from opening  96   b.  The width of the slots  96   a,    96   b  is such that the respective mounting tabs  70  of the terminal quick connects fit into the slots to both capture the terminal quick connects in the terminal blocks, and align the terminal quick connects with respect to each other and the heater unit. 
     During fabrication of a heater unit, the ends  14   a,    14   b  of heating element  14  are inserted through the bores B in body  12  so to extend a distance past flange  12   b.  Insulation is stripped from the ends of the respective leads L 1 , L 2  exposing strands of wire at the end of each lead. The lead ends are then inserted in slot  50  of the respective terminal quick connects and pulled through the slots into the recess  64  formed in sidewall  62  of the terminal quick connect. Engagement tab  60  is then pressed upwards against the wire to partially close the slot and attach the lead to the terminal quick connect. 
     After the leads are attached to the terminal quick connects, the mounting tab  70  of the respective units is aligned with the slot  98   a,    98   b.  This further aligns the tabs  38   a,    38   b  with a projecting end of heating element  14 . When tab  70  is pushed into the slot  98   a  or  98   b,  the end of the heating element is pushed the notches  42   a,    42   b  formed in the tabs  38   a,    38   b.  This action deforms the tabs about the heating element so they frictionally engage the end of the heating element. When both terminal quick connects are in place, the base  100  of terminal  24  is seated against outer face  26  of flange  12   b  and secured to the face in any convenient manner. None of the above described process steps require use of screw drivers or similar tools previously required to complete the installation. 
     What has been described is apparatus and a method for attaching the terminal ends of the heating element into an electrical circuit by which current is directed through the heating element. The apparatus includes the combination of a pair of terminal quick connects made of an electrically conductive and a terminal block made of a non-conductive material in which the terminal quick connects are installed. A separate quick connect electrically connects each end of the heating element with an electrical lead, and both terminal quick connects are installed in the terminal block. One end of the heating element is frictionally engaged by one portion of the terminal quick connect and an electrical lead is captured in another portion of the terminal quick connect. Importantly, no tools are required to make the electrical connections or permanently attach the terminal quick connects to the terminal block. Once installed on the terminal blocks, the terminal quick connects are electrically isolated from each other so the terminations cannot short together. Finally, the method and apparatus of the invention simplifies manufacture of the heating unit and lowers the manufacturing cost of a heating unit, while providing a reliable heating unit which is readily installed and replaced. 
     In view of the foregoing, it will be seen that the several objects of the invention are achieved and other advantageous results are obtained. 
     As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.