Patent Publication Number: US-6709282-B2

Title: Waterproof connector

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a waterproof connector in which watertightness is not easily reduced due to an inappropriate installation process. 
     2. Description of the Related Art 
     There is proposed a waterproof connector which is provided with a connector housing having a plurality of terminal housing chambers for receiving metal terminals. A metal terminal is provided with first and second crimp portions. The first crimp portion clamps an insulated cable to electrically contact and the second crimp portion clamps a rubber plug. When the metal terminal is received in the terminal housing chamber, the rubber plug is fitted thereto so as to be watertight. 
     Japanese patent application laid-open H7-245149 discloses such an art of the proposed waterproof connector. 
     SUMMARY OF THE INVENTION 
     According to the proposed waterproof connector, the inner diameter A of the terminal housing chambers is secured to be large enough as compared to the outer diameter B of the insulated cable so that clearance between the first crimp portion clamping the insulated cable and the terminal housing chamber is assured. Thereby the first crimp portion may not scratch an inner surface of the terminal housing chamber in the course of the waterproof connector assembly. 
     However, if the inner diameter A is relatively small due to miniaturization of the waterproof connector, an appropriate clearance between the first crimp portion and the terminal housing chamber is not assured, the terminal housing chamber may be often scratched, then reducing watertightness. 
     The present invention is accomplished in view of the above problem and intends to provide a waterproof connector of a small-size, watertightness of which is not easily reduced due to an inappropriate installation process. 
     According to the present invention, the waterproof connector is provided with one or more terminals each including a contact, a first crimp portion and a second crimp portion, insulated cables respectively having leading conductor clamped by the first crimp portion, rubber plugs respectively fitted on the insulated cable, being clamped by the second crimp portion and a connector housing including terminal housing chambers respectively housing the terminals. The rubber plugs are fitted into the respective terminal housing chambers so as to be waterproof. Each of the second crimp portions has a larger width than height thereof in a state where the second crimp portion clamps the rubber plug. 
     A top end or a bottom end of the second crimp portion may cause scratches to the terminal housing chamber because the top end and the bottom end often have burrs due to the manufacturing process thereof. Each of the second crimp portions is formed to have a larger width than height thereof so that clearance between the top and bottom end thereof and the terminal housing chamber are broad enough to avoid scratching the terminal housing chamber. Thereby excellent watertightness is assured. 
     More preferably, the terminal housing chambers are respectively formed in a cylindrical hollow shape and sizes of the terminal housing chambers and the terminals are formed to satisfy the following inequalities; 
     
       
           B/A&gt; 0.6 and  D/C&lt; 1,  
       
     
     where A is an inner diameter of the terminal housing chamber, B is an outer diameter of the insulated cable, C, D are respectively the width and height of the second crimp portion in a state where the second crimp potion clamps the rubber plug. 
     Miniaturizing the connector makes a B/A ratio larger to be close to 1. In a case where the B/A ratio is more than 0.6, scratching is highly likely to happen. Because the D/C ratio is kept at less than 1 in such a case, scratching is avoided and watertightness is assured. 
     Further preferably, each of the second crimp portions has an oval cylinder shape in a state where the second crimp portion clamps the rubber plug. The rounded shape prevents the second crimp portions from scratching the terminal housing chamber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a waterproof connector according to an embodiment of the present invention; 
     FIG. 2 is a plan view of the terminal of the waterproof connector; 
     FIG. 3 is a side view of the terminal of the waterproof connector; 
     FIG. 4 is a close-up side view of the terminal of the waterproof connector showing the vicinity of a second crimp portion thereof; 
     FIG. 5 is an explanation drawing explaining the relationship of the second crimp portion and a terminal housing chamber of the connector; 
     FIG. 6 is a perspective view of the waterproof connector in a state where the terminal is ready to be housed therein. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A preferred embodiment of the present invention will be described hereinafter with reference to FIGS. 1 to  6 . 
     The waterproof connector  10  is provided with a connector housing  11  which is made of resin and has a box-like shape. A plurality of terminal housing chambers  12  penetrate the connector housing  11  from a front end to a rear end thereof. A front half of the respective terminal housing chamber  12  is surrounded by a circumferential wall  12   a  to be of a rectangular tube shape and a rear half is surrounded by a sealing surface  12   b  to be of a cylindrical tube shape. 
     An insulated cable  19  with a rubber plug  20  fitted thereto is inserted to a rear end of the terminal housing chamber  12 . The rubber plug  20  is in close contact with the sealing surface  12   b  so that the terminal housing chamber  12  is assured to be watertight. 
     Each terminal housing chamber is integrally provided with a resilient latch arm  13  diagonally extending from an upper surface thereof to a front end of the terminal housing chamber  12  so that a main body  31  of a terminal  30  housed in the circumferential wall  12   a  of the terminal housing chamber  12  is engaged therewith. Circular rubber packings  14  are respectively fitted to outer surfaces of the circumferential walls  12   a . Tubular spacers  15  are respectively slidably fitted into the circumferential walls  12   a  so as to press the circular rubber packings  14 . The tubular spacers  15  are made of synthetic resin and formed in a box-like shape. Each tubular spacer  15  is provided with a barrier wall  16  and an end portion  16   a  of the barrier wall  16  is in contact with a proximal end of the respective resilient latch arm  13  so as to prevent upward elastic deformation. Thereby the terminals  30  are doubly latched with the resilient latch arms  13  and the tubular spacers  15 . The tubular spacers  15  are respectively provided with rectangular apertures  17  corresponding to the terminal housing chambers  12  for receiving opposite terminals (not shown). 
     The insulated cable  19  is composed of a conductor  19   a  and an insulation sheath  19   b  covering the conductor  19   a  as shown in FIG.  5 . An end of the insulation sheath  19   b  is removed and an end of the conductor  19   a  is exposed. The leading conductor  19   a  is clamped by a first crimp portion  32  of a terminal  30  (to be described later). 
     The rubber plug  20  is integrally provided with a connection portion  21  for attaching to a second crimp portion  33  of the terminal  30 , a sealing portion  22  having a plurality of torus-like portions for closely contacting the sealing surface  12   b  of the terminal housing chamber  12  and a proximal portion  23  for closely contacting with a peripheral surface of the insulated cable  19 . The sealing portion  22  and the proximal portion  23  have larger diameter than the sealing surface  12   b  of the terminal housing chamber  12 . 
     The terminal  30  is provided with a contact  31  having a rectangular tube-like shape at a proximal end thereof, a first crimp portion  32  having a pair of crimp arms for clamping the conductor  19   a , a second crimp portion  33  having a pair of crimp arms for clamping the connection portion  21  of the rubber plug  20 . Both sides of the first crimp portion  32  and the second crimp portion  33  are integrally connected by a pair of side walls  34 . The terminal  30  is inserted into the terminal housing chamber  12  from the rear end thereof so that a proximal end  31   a  of the contact  31  is latched by a distal end of the resilient latch arm  13 . The whole body of the terminal  30  is made from a blanked metal sheet (not shown). A metal sheet is blanked and bent in a predetermined shape of the terminal  30 , therefore it rarely happens that burrs  35  are formed due to production tolerance as shown in FIG.  4 . The burrs  35  often cause scratching the sealing surface  12   b.    
     Width C of the second crimp portion  33  clamping the connection portion  21  is larger than height D thereof as shown in FIG.  5 . More specifically, the terminal  30  is formed so that an inequality D/C&lt;1 is assured to be satisfied whenever an inequality B/A&gt;0.6 is satisfied, where A is an inner diameter of the sealing surface  12   b  of the terminal housing chamber  12  and B is an outer diameter of the insulated cable  19 . 
     For example, a compact waterproof connector  10  is formed so that A is 2.6 mm, B is 1.8 mm, C is 2.3 mm and D is 2.1 mm. In such a case, B/A=0.69&gt;0.6 and D/C=0.91&lt;1 are satisfied. Though the inner diameter A of the terminal housing chamber  12  can be smaller, the outer diameter B of the insulated cable  19  may be limited. Therefore miniaturizing the connector makes a B/A ratio larger to be close to 1. In a case where the B/A ratio is more than 0.6, scratching of the sealing surface  12   b  by the terminal  30  is highly likely to happen. The critical ratio of B/A=0.6 is determined by the above consideration. 
     Furthermore, a width and a height of the contact  31  are respectively smaller than the width C and the height D of the second crimp portion  33 , thereby the waterproof connector  10  is formed smaller. The width C of the second crimp portion  33  is smaller than the inner diameter A of the sealing surface  12   b  of the terminal housing chamber  12 . 
     According to the above described embodiment of the present invention, the waterproof connector  10  is formed so that the inequality D/C&lt;1 is assured to be satisfied whenever the inequality B/A&gt;0.6 is satisfied, where A is the inner diameter of the sealing surface  12   b  of the terminal housing chamber  12 , B is the outer diameter of the insulated cable  19 , C is the width of the second crimp portion  33  and D is the height of the second crimp portion  33 . Thereby the crimp portion  33 , the burrs  35  and such do not easily scratch the sealing surface  12   b  of the terminal housing chamber  12  in course of inserting the terminal  30 . 
     The height of the terminal  30  slightly has some variation due to a production error because the blanking burrs stand in a vertical direction and the terminal  30  is easy to be bent upward or downward. Moreover, the terminal  30  is often inserted into the terminal housing chamber  12  in a slanted direction. The width C of the second crimp portion  33  is larger than the height D thereof so that a considerable clearance between the second crimp portion  33  and the sealing surface  12   b  is assured to prevent scratching. On the contrary, the width of the terminal  30  is formed more precisely than the height thereof. 
     As described above, the sealing surface  12   b  is not easily to be scratched and the rubber plug  20  can be in close contact thereto, thereby excellent watertightness is assured. 
     Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art, in light of the above teachings. For example, according to the above description, the crimp portions are bent in an oval tube as shown in FIG.  5 . The crimp portions may be bent in a rectangular tube instead.