Patent Publication Number: US-6222133-B1

Title: One-piece ceramic terminal insulator mounting arrangement

Description:
FIELD OF THE INVENTION 
     This invention relates to a one-piece ceramic terminal insulator for use in mounting an electrical connecting terminal through a support wall of an apparatus. In particular, the present invention relates to a ceramic terminal insulator mounting arrangement for use with a heating assembly in a clothes dryer. 
     BACKGROUND OF THE INVENTION 
     In the manufacture of heating assemblies for use in clothes dryers, it is common practice to mount a helical coil on insulators relative to a heating housing. Electrical connection of electrical energy to the heating coils is typically provided through a terminal assembly mounted in a sidewall of the heater housing comprising an electrical connector terminal and an insulator. 
     One such terminal assembly is shown in U.S. Pat. No. 5,623,126 issued to Jimmy L. Sherrill on Apr. 22, 1997. This patent teaches a two piece ceramic insulator comprising male and female parts which cooperate with a relatively flat or blade like terminal connector passing through the male and female members. This two piece ceramic insulator requires the assembly of the two parts relative to the supporting wall and must be held in place while a relatively flat connector terminal blade is passed through a center aperture in the male and female parts. The flat terminal blade has tabs which engage the female portion of the ceramic insulator to limit the travel of the blade terminal through the ceramic insulator. The other end of the terminal blade must be bent in order to maintain the male and female insulator members in mating relationship. This insulator is difficult to assemble because it requires holding the male and female members together while the terminal blade is passed through the insulators. Further, the terminal blade is crimped onto the end of a regular terminal. Accordingly, a disadvantage associated with this ceramic terminal insulator assembly is that it is difficult and labour intensive to assemble through the supporting wall of the heater assembly. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a one-piece ceramic terminal assembly which is readily mounted through a supporting wall of a heater housing. 
     The present invention relates to a terminal assembly comprising a one-piece ceramic insulator for mounting an electrical conductor therethrough and relative to a support wall of a heater housing. The insulator has a central block extending along a longitudinal axis and between first and second ends thereof. The central block has a passageway extending through its center between the first and second ends for receiving the electrical conductor. The central block passes through a first aperture in the supporting wall and has a diameter less than the diameter of a central opening in the first aperture. The first aperture has at least one slot extending outward from the central aperture. The insulator includes at least a first wing extending out from the central block adjacent the first end a first distance greater than the diameter of the central opening of the first aperture and less than the at least one slot to permit the passage of the first wing through the first aperture. The insulator includes a second wing extending out from the central block adjacent the second end spaced axially and readily offset of the central block from the first opposing first wing. The second wing is larger than the at least one slot in the supporting wall so as to engage a second opposing side of the supporting wall and prevent the second wing from passing through the first aperture. 
     Advantage is found with the present invention in that a one-piece insulator does not have to be assembled and can be passed through a supporting wall aperture and rotated such that the first and second wings axially spaced along the central block of the insulator are rotated into engagement with opposing side surfaces of the supporting wall. Such a one-piece ceramic insulator is easy to assemble within the heating assembly. The electrical conductor may be a relatively flat blade member that passes through the passageway in the ceramic insulator. 
     Another aspect of the one-piece ceramic insulator of the present invention is that the central block may have concave surfaces extending from the first end to the second end of the central block between the first and second wings to define an air gap passageway between the central block and the aperture in the supporting sidewall. This gap allows air to be drawn in across the ceramic insulator towards the heating elements and thereby cool the ceramic insulator and prevent it from overheating due to the passage of electrical current through the electrical conductor. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the nature and objects of the present invention, reference may be had to the accompanying diagrammatic drawings in which: 
     FIG. 1 is an elevation view showing the positioning of heating elements around the perimeter of a dryer support wall and the electrical connection through the dryer support wall utilizing the electrical terminal assembly and mounting arrangement of the present invention; 
     FIG. 2 is an isometric view of the one-piece terminal of the present invention; 
     FIG. 3 is an end view of the one-piece terminal insulator; 
     FIGS. 4 a ,  4   b , and  4   c  illustrate an end view of the assembly of the insulator in the supporting wall; 
     FIG. 5 is a side view showing the steps involved to insert the insulator through th supporting wall; and, 
     FIG. 6 a ,  6   b , and  6   c  illustrate and end view of the assembly of the insulator in the supporting wall wherein the aperture in the supporting wall has two diametrically opposed radially extending slots. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1, a heater assembly  10  suitable for use in a clothes dryer is shown. The heater housing  10  has a support wall  12  with a peripheral wall  14  and a rim  16 . Wall  14  includes first openings for securing thermostats  18  to the heater assembly  10 . In the embodiment shown in FIG. 1 four securing bolts  20   a, b, c  and  d  respectively, are shown for further retaining the heater assembly  10  in place relative to the dryer (not shown). Two helical wound heater coils  22  extends around the perimeter of support wall  12 . Heater coils  22  are retained in position by a series of heater coil mounting support brackets  28  that are secured to the support wall  12 . One end of the heater coils  22  is connected to a power source via electrical conductor terminals  24 , and the other ends is connected to electrical conductor terminals  26 . 
     Conductors  24  and  26  pass through electrical insulators  30 . The insulators  30  pass through terminal apertures  32  in the supporting wall  14 . The insulators  30  are mounted to the supporting wall  14  engaging first and second opposing sides  34 ,  36  of the supporting wall  14 . In FIG. 1, insulators  30  supporting terminals  24  are shown mounted through the supporting wall  14  in an opposite manner to the insulators  30  supporting terminals  26 . 
     Referring to FIGS. 4A and 6A, a portion of the supporting wall  14  looking at the outside surface  34  is shown to include the terminal or first aperture  32  passing through the supporting wall  14 . In the embodiment of FIG. 4A, the first aperture  32  has a central opening  38  and one slot  40  extending outwardly from the central opening  38  of the first aperture  32 . In the embodiment shown if FIG. 6A, the aperture  32  has a central opening  38  with a pair of slots  40 ,  42  extending outwardly from the central opening  38  and being radially diametrically opposed from one another. The use of one or two slots  40 ,  42  has an effect on the positioning of the insulator  30  relative to the aperture  32  during the insertion of the insulator  30  through the sidewall  14 . These differences will be explained in more detail hereinafter. 
     Referring to FIGS. 2 and 3 there is shown the one-piece ceramic insulator of the present invention. The ceramic insulator  30  has a central block  44  having a generally circular diameter at its outer surfaces. The central block  44  extends along a longitudinal axis  46  between first and second ends  48 ,  50  of the central block  44 . The central block  44  has a passageway  52  extending therethrough between the first and second ends  48  and  50  for receiving one of the electrical conductor terminals  24 ,  26  (see FIG.  1 ). The passageway  52  is a circular passage with slotted sides so as to receive a relatively flat terminal assembly blade like shaped terminal or circular terminal. The central block  44  has a diameter  39  that is less than the diameter  38  of the first aperture  32 . 
     The central block  44  includes a first pair of diametrically opposed first wings  54  which extend out from the central block  44  adjacent the first end  48  a distance which is greater than the diameter of the central opening  38  and less than the at least one slot  40 ,  42 . 
     The central block  44  further includes a second pair of diametrically opposed second wings  60  which extend out from the central block  44  adjacent the second end  50 . The second pair of wings  60  are spaced axially along the longitudinal axis  46  from the first pair of wings  54 . Further, the second pair of wings  60  are offset radially relative to the first pair of wings  54 . The second wings  60  are larger in size than the slots  40 ,  42  so as to engage one of the sides of the supporting wall  14 . 
     The central block  44  further includes concave shaped surfaces  62  that extend between the first and second ends  48 ,  50  of the central block  44  and between the first and second wings  54 ,  60 . The concave surfaces  62  define an air gap  64  between the concave surface  62  and the central opening  38  of the aperture  32  which is shown in FIG. 3 between the concave surface  62  and dotted line  38  representing the central opening of the aperture  32 . 
     Referring now to FIGS. 4A,  4 B,  4 C and FIG. 5, the assembly of the insulator  30  relative to the supporting wall  14  will now be described for the insulators  30  that support terminal  26  in FIG.  1 . It should be understood that this method of assembly may be used for the insulators  30  that support terminals  24  when inserted through the supporting wall  14  from the opposite direction. 
     To insert the terminal  30  through aperture  32  in the supporting wall  14 , the terminal  30  is moved as shown in FIG.  5 (A) towards the surface  32  of the supporting wall  14 . As the terminal  30  is moved towards supporting surface  32 , it is angled so that the lower wing  54  passes through the central opening  38  of the aperture  32 . Next the terminal  30  is pivoted as shown in FIGS.  5 (B), (C), and (D), so that the upper wing  54  passes through the slot  40  in the aperture  32 . At this time, the larger second wings  60  engage the surface  32  preventing any further forward movement of the terminal  30  through the aperture  32 . 
     FIG. 4B shows the mounting of the insulator  30  through the aperture  32  in end view. The insulator  30  is then rotated in the direction of arrow  70  shown in FIG. 4C so as to rotate the wings  54  relative to the slot  40  and bring the wings  54  into engagement with surface  34  of the supporting wall  14 . 
     The difference between the method of assembly shown in FIGS. 4 and 5 relative to that shown in FIG. 6 is that the additional aperture  42  shown in FIG. 6A permits the direct insertion of the insulator  30  through the aperture  32  without having to first insert one wing  54  and pivot the other wing through slot  40 . Again, the insulator  30  is rotated in the direction of the arrow  70  to move the insulator into position. While arrows  70  are shown rotating the insulator in a clockwise fashion, it should be understood that the insulator could be rotated in a counterclockwise direction if this was more appropriate. 
     The electrical conductor terminals  26  are pushed through the passageway  52  and bent as shown in FIG. 1 at  75 . This prevents the terminal block  30  from rotating relative to the aperture  32  and disengaging itself from the aperture. It should be understood that electrical conductor terminals  24 ,  26  can be pre-assembled to insulators  30  prior to the insulators  30  being assembled to the supporting wall  14 . Further, the conductor terminals  24 ,  26 , alternatively can be bent against one of the ends  48 ,  50  of the insulator  30  to prevent rotation of the insulator  30 . 
     From the foregoing it will be seen that the use of a one-piece ceramic insulator with electrical contact may be readably mounted through a supporting wall of the heating assembly.