Terminal for shielding connectors and shielding connector
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a terminal mounted in a shielding connector used for electric wiring of a vehicle and to a shielding connector. &#34;Shielding connector&#34; used herein is intended to mean a connector with a structure that provides connections for the inner conductor of a shielded cable and for the shielding layer of the cable at a time. 
     2. Description of the Prior Art 
     A shielded cable such as a coaxial cable or multicored shielded cable includes at an outer layer portion a shielding layer formed of a braided conductor. When such a shielded cable is connected to an electric instrument or to another shielded cable, it is necessary that not only the conductor but also the shielding layer be connected. 
     In order for a shielding layer to be connected, part of the outer sheath is conventionally removed to expose the shielding layer, followed by twisting of the exposed layer into a single wire. The wire is then at its front end soldered, or screwed via a terminal attached to its front end, to a shielding case or the like. 
     The connecting operation according to the above, however, is exceedingly inefficient. 
     To make an improvement in connecting means of shielding layers, as shown in FIG. 2 Japanese Utility Model Publication No. Hei 2-18533 proposes a shielding connector k in which a drain wire b electrically connected to a shielding layer a of a cable c is connected to a shielding case e of a mating housing via a shielding terminal d crimped on the drain wire b. 
     If, however, the shielding terminal d is directly crimped on the drain wire b as in the shielding connector k, a friction is caused between an edge g of the rear crimp portion f of the terminal d and the drain wire 6 as shown in FIG. 8 by the swinging of the drain wire b due to vibration and the like in use, resulting in possible severance of the drain wire b. 
     To prevent the severance by friction, it must be arranged for example that as shown in FIG. 9 the rear crimp portion f is crimped on the drain wire b via a flexible tube h through which the wire b is passed. This exceedingly lowers the operability. 
     SUMMARY OF THE INVENTION 
     This invention has been accomplished to overcome the above drawback and its object is to provide a reliable terminal for shielding connectors and a shielding connector, which enable an easy and secure connection between a shielding wire and a shielding case, and which are excellent in operability for assembly. 
     In order to attain the object, according to an aspect of this invention, there is provided a terminal for shielding connectors formed from a conductive plate in one piece, which comprises: a forward electric contact portion for contact with a mating terminal, a drain wire crimp flap crimped on a drain wire leading from a shielding layer of a shielded cable, shielded cable-holding means located at a position rearwardly of the drain wire crimp flap for holding the shielded cable, and contact means for shielding. 
     According to another aspect of this invention, there is provided a shielding connector which comprises: a terminal housing provided with a plurality of terminal accommodating chambers, a shielding case that houses the terminal housing, and a terminal mounted in the terminal housing, the terminal comprising a forward electric contact portion inserted in one of the terminal accommodating chambers for contact with a mating terminal, a drain wire crimp flap crimped on a drain wire leading from a shielding layer of a shielded cable, shielded cable-holding flaps crimped on an outer sheath of the shielded cable at a position rearwardly of the drain wire crimp flap, and contact means for shielding, wherein the contact means for shielding is brought into contact with the shielding case on assembling the terminal housing into the shielding case. 
     The terminal for shielding connectors has, in addition to a drain wire crimp flap, a shielded cable holding means. Thus, the drain wire electrically connected with the shielding layer of a shielded cable is connected to the terminal by crimping with the drain wire crimp flap, while the shielded cable holding means is crimped on the outer sheath of the cable to hold the cable. Consequently, the shielded cable is fixedly held by the shielded cable-holding means, thereby excluding friction between an edge of the crimp flap and the drain wire caused by friction and the like in use and possible severance of the drain wire. 
     Further, in the shielding connector of this invention, the connection between the shielding layer of a shielded cable and the shielding case is made when the contact means for shielding of the terminal is brought into contact with the shielding case. As a result, it becomes possible that on fitting into the shielding case the terminal housing having the terminal assembled therein, the contact means for shielding is contacted with the shielding case to effect shielding. 
     Further objects and advantages of this invention will be apparent from the following description of the Preferred embodiment of the invention as illustrated in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a terminal for shielding connectors as one embodiment of this invention; 
     FIG. 2 is a perspective view of the terminal of FIG. 1 with a shielded cable attached thereto; 
     FIG. 3 is a perspective view showing the terminal of FIG. 2 mounted in the terminal housing of a shielding connector; 
     FIG. 4 is a perspective view of a shielding connector as one embodiment of this invention with its constituents, terminal housing, shielding case and housing cover shown disassembled; 
     FIG. 5 is a perspective view of the shielding connector of FIG. 4, shown assembled; 
     FIG. 6 is a sectional view taken along the line X--X of FIG. 5; 
     FIG. 7 is a perspective view of a conventional shielding connector; 
     FIG. 8 is a side view showing the junction of the drain wire and the terminal in FIG. 7; and 
     FIG. 9 is a side view showing one example of conventional means for protecting the drain wire at the juntion of FIG. 8. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     FIG. 1 is a perspective view of a terminal A for shielding connectors according to one embodiment of this invention. 
     The terminal A--which is formed by folding a conductive plate of metal such as brass through press processing --has at one end a female electric contact portion 1 for receiving a mating terminal and at the other end a pair of opposed shielded cable-holding flaps 2, 2. At intermediate portions, the terminal A has a pair of opposed drain wire crimp flaps 3, 3 and shielding contact portions 5, 5 folded to have a legs-shape. 
     The electric contact portion 1 has an electric contact piece 1a extended from its front end and folded back into the electric contact portion 1. 
     The shielding contact portions 5 are shaped so as to be adapted to a later-described shielding case and each has resilient contact pieces 6 cut and raised at its outer and upper sides. 
     FIG. 2 is a perspective view of a shielded cable 7 attached to the terminal A as mentioned above. A drain wire (exposed conducting wire) 10 leading from the shielding layer of the shielded cable 7 is connected to the terminal A by the crimp flaps 3 crimped on the drain wire 10. The shielded cable holding flaps 2 are crimped on the outer sheath 7a of the shielded cable 7 to hold the shielded cable 7. A female terminal 9 is attached to each of the covered wires 8 inside the shielded cable 7. 
     Description is now made of the steps for mounting the above-obtained shielded cable-attached terminal A in a shielding connector S (later described). 
     FIG. 3 shows the shielded cable-attached terminal A disposed in a terminal housing 11, a constituent of the shielding connector S. 
     The terminal housing 11 has at the front end portion a plurality (three in the embodiment shown) of terminal accommodating chambers 12A, 12B and 12C, and at the rear end portion a shielded cable-mounting portion 11a wherein the shielding contact portions 5 of the terminal A are accommodated. 
     The electric contact portion 1 of the terminal A is inserted into the central terminal accommodating chamber 12B (not shown), and the female terminals 9 attached to the covered wires 8 are inserted into the other terminal accommodating chambers 12A and 12C. 
     The shielding contact portions 5 of the terminal A are fitted between the side walls 11b of the shielded cable-mounting portion 11a, and the lateral resilient contact pieces 6 project outwardly of the side walls 11b through respective openings 11c formed therein. The upper resilient contact pieces 6 are raised beyond the top of the side walls 11b. 
     FIG. 4 is a perspective view of the shielding connector S according to one embodiment of this invention, with its constituents, terminal housing 11, shielding case 13 and housing cover 14 shown separated. 
     The terminal housing 11 with the shielded cable-attached terminal A assembled thereon on is fitted into the shielding case 13 as indicated by an arrow in FIG. 4. In this instance, the shielding case 13 is usually first assembled into the housing cover 14, followed by fitting the terminal housing 11 into the shielding case 13, although the shielding case 13 is shown separated from the housing cover 14 in FIG. 4. 
     FIG. 5 is a perspective view of the shielding case 13 and terminal housing 11 assembled into the housing cover 14. 
     The shielding case 13, as shown in FIG. 6, includes a hollow circumferential wall 13a fabricated from a synthetic resin material and a conductive layer (not shown) metallized on a surface 13b of the circumferential wall 13a. The circumferentail wall 13a may optionally be formed from a metal plate. The shielding case 13 houses the entire terminal housing 11 to effect shielding. On insertion of the terminal housing 11 into the shielding case 13, the resilient contact pieces 6 of the terminal A project outwardly of the terminal housing 11 and resiliently contact the conductive layer on the shielding case 13 or the metal plate constituting the shielding case 13, so that the drain wire 10 of the shielded cable 7 is connected with the shielding case 13 via the terminal A. 
     The housing cover 14 is fabricated from an insulating synthetic resin material and houses the shielding case 13 (and the terminal housing 11 assembled therein) for its protection and electrical insulation against the outside. 
     As described above, this invention has the following features and advantages. Since the terminal for shielding connectors is provided with shielded cable-holding flaps in addition to the drain wire crimp flaps, the crimp flap-crimped drain wire is fixedly held by the shielded cable-holding flaps, thereby excluding friction between an edge of the crimp flaps and the drain wire caused by vibration in use and possible unfavorable phenomena such as severance of the drain wire. Further, owing to the structure whereby the shielding contact pieces resiliently contact the shielding case, the shielding wire is connected to the shielding case on fitting the terminal housing into the shielding case in the housing cover, resulting in a marked improvement in operability for assembling the shielding connector. 
     In addition, since the electric contact portion and the shielding wire crimp flaps may be provided in shape similar to those of terminals attached to electric wires other than the shielding wire, the pressure-welding of the shielding wire to the terminal may be effected concurrently with the pressure-welding of other electric wires, advantageously resulting in an improvement in productivity and reliability.