Patent Publication Number: US-5833476-A

Title: Rotary connector apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation in part of U.S. application Ser. No. 08/444,040 filed May 18, 1995, now U.S. Pat. No. 5,645,441. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a rotary connector apparatus mounted on, for example, a pad portion of an automotive steering wheel for supplying electric power to an air bag or the like. More specifically, the present invention relates to an improvement of a structure for connecting the flexible cable of the rotary connector apparatus with a wire harness. 
     2. Description of the Related Art 
     A conventional rotary connector apparatus is disclosed, for example, in Japanese Patent Publication No. JP A-7-263105. The external connection harness of the conventional rotary connector apparatus has a plurality of core wires fixed on each terminal piece using an electric resistance welding method, an ultrasonic wave welding method, or the like. 
     However, a problem exists when connecting the external connection harness of the conventional rotary connector apparatus. Specifically, in the external connection harness of the conventional rotary connector apparatus, when each of the core wires is welded on each terminal piece, the multiple strands of the core wires are scattered as shown in the drawings of the above-mentioned Japanese Patent Publication No. JP A-7-263105, thereby resulting in an unstable quality of the welded portion. To overcome this problem, the conventional core wire of the external connection harness has been fixed by using a compression press work, a soldering work, a return work, or the like in order to prevent scattering at the welded portion. 
     However, when the core wire in the external connection harness of the rotary connector apparatus is fixed at the welded portion by using the compression press work, the welding work, the return work or the like, the number of process steps and manufacturing cost is undesirably increased. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved rotary connector apparatus that overcomes the problems associated with the conventional rotary connector apparatus described above. 
     More specifically, it is an object of the present invention to fix the core wire of a wire harness of a rotary connector to a wire harness by providing a holding portion in the form of a through hole for holding the end point of the wire harness on a supporter. 
     Additional objects, advantages and novel features of the invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     In accordance with the present invention, in order to solve the problems described above, a rotary connector apparatus is provided comprising: a stator housing; a rotor housing mounted rotatably on the stator housing; a flexible cable received in a spiral formation within a space formed between the stator housing and the rotor housing; a terminal electrically connected to an electric wire exposed from the flexible cable; a supporter molded with the terminal and fixed on at least one of the stator housing and the rotor housing; and a harness connected to the terminal. The rotary connector apparatus is characterized by the supporter having a through hole into which a core wire or a coating film at an end point of the wire harness is inserted. 
     The supporter preferably has a recess portion formed therein. A welding portion of the terminal is exposed in the recess portion. A press groove is formed in the supporter into which a coating film of the wire harness is inserted, the press groove being located adjacent to the recess portion. 
     In a first embodiment of the present invention, the through hole extends through the recess portion of the supporter adjacent to the terminal, and a coating film covers the end point of the core wire inserted into the through hole. 
     In a second embodiment of the present invention, the through hole extends through the recess portion of the supporter adjacent to the terminal, and the end point of the core wire inserted into the through hole is exposed, thereby increasing a contact area between said core wire and said terminal. 
     In a third embodiment of the present invention, the through hole is formed through the terminal, which is formed within the supporter by insert molding. 
     In accordance with another aspect of the present invention, a rotary connector apparatus is provided which comprises a stator housing, a rotor housing mounted rotatably on the stator housing, a flexible cable received in a spiral formation within a space formed between the stator housing and the rotor housing, a terminal electrically connected to the flexible cable, a harness having at least one multistrand core wire electrically connected to the terminal, and a supporter molded with the terminal and fixed on at least one of the stator housing and the rotor housing. The rotary connector apparatus is characterized by the supporter comprising a through hole means for holding an end portion of the core wire and preventing individual strands of the core wire from scattering when a portion of the core wire adjacent to the end portion is electrically connected to the terminal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more clearly appreciated as the disclosure of the invention is made with reference to the accompanying drawings. In the drawings: 
     FIG. 1 is an exploded perspective view showing a rotary connector apparatus according to a first embodiment of the present invention. 
     FIG. 2 is a plan view showing the supporter according to the first embodiment of the present invention. 
     FIG. 3 is a side view showing the supporter according to the first embodiment of the present invention. 
     FIG. 4 is an enlarged sectional view showing the supporter according to the first embodiment of the present invention. 
     FIG. 5 is an enlarged perspective view showing the main portion of the supporter in which the wire harness is removed according to the first embodiment of the present invention. 
     FIG. 6 is an enlarged sectional view showing the supporter according to a second embodiment of the present invention. 
     FIG. 7 is an enlarged sectional view showing the supporter according to a third embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A first embodiment of the present invention will now be described, by way of example, with reference to FIGS. 1 to 5 of the accompanying drawings. 
     The rotary connector apparatus includes a stator housing 1 mounted on a combination switch of, for example, an automobile. A rotor housing 2 is rotatably mounted on the stator housing 1 and coupled to a steering wheel (not shown) by using a connection pin 3. The rotor housing 2 is provided with the connection pin 3 and a pair of resilient claws 2a on which a cover 8 is mounted. 
     At the portion adjacent to the resilient claws 2a, a mounting hole 2b is provided in order to mount the supporter 6. The supporter 6 is disposed under the mounting hole 2b, and the cover 8 is disposed above the mounting hole 2b. The peripheral portion of the mounting hole 2b is secured by the supporter 6 and the cover 8. The connection pin 3 is projected from the upper surface of the rotor housing 2 and coated by a resilient rubber or the like. 
     The flexible cable 4 is, as shown in FIG. 3, a so-called flat cable having electric wires 4a that are molded together by a resin film 4b. The flexible cable 4 is received within the doughnut-shaped space formed between the stator housing 1 and the rotor housing 2. One end of the flexible cable 4 is connected with the stator housing 1, and the other end thereof is connected with the rotor housing 2, respectively. 
     A terminal 5 is made of a metallic material, such as copper or the like, and molded within the L-shaped resin supporter 6 by using an insert molding method. The terminal 5 has a plurality of terminal pieces 5a to be connected to each of the electric wires 4a, which are arranged in parallel within the flexible cable 4. The terminal 5 also has a plurality of welding portions 5b to be connected to each of the core wires 7a of the wire harness 7. The terminal pieces 5a provide a connecting portion for the electric wires 4a, which connecting portion is projected from the supporter 6 as shown in FIG. 3. The welding portion 5b is exposed within the recess portion 6a of the supporter 6, as shown in FIGS. 2, 4 and 5, and fixed with the core wire 7a by using electric resistance welding, ultrasonic wave welding, or the like. 
     The supporter 6 is made of molded resin which is insert molded about the terminal 5. As shown in FIG. 1, the supporter 6 is fixed on the rotor housing 2. However, the supporter 6 can also be secured on the stator housing 1. As shown in FIG. 1, the wire harness 7 having a connector 9 at its end is mounted to the supporter 6 by passing through the mounting hole 2b from the lower surface of the rotor housing 2. The wire harness 7 is secured on the rotor housing 2 by fitting the cover 8 to the resilient claws 2a. The cover 8 is fixed on the supporter 6 by using screws. Thus, the supporter 6 serves as a junction member for electrically connecting the flexible cable 4 with the external connection harness 7. 
     The supporter 6 has the welding portion 5b of the terminal 5 in the recess portion 6a, and the through hole 6b at the portion adjacent to the recess portion 6a. The through hole 6b is provided for supporting the coating film 7d at the end point of the wire harness 7, which is inserted into the through hole 6b. The through hole 6b, the welding portion 5b, the recess portion 6a, and the press groove 6c of the supporter 6 are aligned on the same line. 
     The recess portion 6a is a hole provided for exposing each of the welding portions 5b of the terminal 5, which is inserted into the supporter 6 by using an insert molding method. The number of recess portions 6a in the supporter 6 is at least as large as the number of core wires 7a in the wire harness 7. The through hole 6b receives the coating film 7d made of resin or the like at the end point of the wire harness 7. The through hole 6b serves as a hole by which the core wire 7a is guided at the center position of the welding portion 5b in the recess portion 6a. The through hole 6b is disposed at the position adjacent a corner of the approximately L-shaped terminal 5. Moreover, the through hole 6b has a circle section, rectangular section, or the like into which each coating film 7d, or all of coating films 7d, is inserted. The structural formation of the through hole 6b, however, is not limited to the specific structure shown in the drawings. For example, the through hole 6b may be a plurality of holes into which each individual coating film 7d is inserted, or a single hole into which all of coating films 7d are inserted. 
     The wire harness 7 is composed of a plurality of core wires 7a having multiple strands coated with the coating film 7b, 7d. A tube 7c covers the core wires 7a and coating film 7b, except the exposed end portions which are coupled with the supporter 6 and terminal 5. As shown in FIG. 1, the wire harness 7 is coupled to the supporter 6 at its one end, and another end thereof is connected to the connector 9. Moreover, the wire harness 7 has, as shown in FIGS. 2 and 3, the supporter 6 forming the holding portion 6b for holding the end point of the wire harness 7. 
     As shown in FIGS. 2 and 4, the coating film 7d supports the wire harness 7 by inserting the coating film 7d into the through hole 6b. The length and the position of the coating film 7d are not limited to the specific structure shown in the drawings. Other arrangements where the wire harness 7 is supported by passing the coating film 7d through the through hole 6b can also be used. 
     The core wire 7a located rearward of the coating film 7d is stripped by using a cutter between the coating films 7b and 7d. The exposed core wire 7a is then welded to the welding portion 5b by using the electric resistance welding method, the ultrasonic wave welding method, or the like. The coating film 7b is supported such that the portion between the welding portion 5b and the tube 7c is fitted into the press groove 6c. 
     As shown in FIG. 1, the cover 8 is secured on the rotor housing 2 such that the contact holes 8a are contacted to the resilient claws 2a projected from the rotor housing 2 adjacent to the mounting hole 2b, and the cover 8 is screwed to the supporter 6 thereby closing the mounting hole 2b. The connector 9 is connected to a counter-side connector (not shown) of the steering wheel. A connector 10 is disposed at the lower surface of the stator housing 1 and may be formed as an integral body with the stator housing 1. The connector 10 is connected to the counter-side connector (not shown) mounted on the steering column or body of the automobile. 
     The operation of a first embodiment of the present invention as described above will now be described by reference to the process of connecting the wire harness 7 to the flexible cable 4. 
     In the wire harness 7, the tube 7c is stripped off from the end of the wire harness, and then the coating film 7b is stripped off from the core wire 7a leaving a coating film 7d at an end portion of the wire harness and an exposed portion of the core wire 7a between the coating film 7d and the coating film 7b. The one end of the core wire 7a is connected with the connector 9. The other end of the wire harness 7, as shown in FIGS. 2 to 4, is held such that the coating film 7d at the end point thereof is fitted into the through hole 6b. As shown in FIGS. 2 to 4, the exposed core wire 7a is disposed on the welding portion 5b at a portion adjacent the coating film 7d located at the end point of the wire harness 7. Each of the coating films 7b is held by being inserted into each of the press grooves 6c. The multiple strands of the core wire 7a in the wire harness 7 are prevented from scattering because the coating film 7d remains at the end point of the wire harness 7, and each end point is inserted into the through hole 6b. Therefore, the core wire 7a does not require any solder or press work for avoiding such scattering during assembly. 
     Each of the coating films 7d of the wire harness 7 is inserted into a respective through hole 6b to position each of the core wires 7a on each of the welding portions 5b, respectively. The coating film 7b within the press groove 6c holds the coating film 7b by being fitted into the press groove 6c with pressure. 
     In the wire harness 7, the coating film 7b and the coating film 7d, which are located at both ends of the exposed core wire 7a welded on the welding portion 5b, are held by the through hole 6b and the press groove 6c. By this structure, the exposed core wire 7a is aligned on the center portion of the welding portion 5b and fixed thereon. The core wire 7a is fixed to the welding portion 5b by using the electric resistance welding method, the ultrasonic wave welding method, or the like. The core wire 7a is prevented from scattering because the coating film 7b and the coating film 7d at the end point thereof are fixed at both sides of the exposed core wire 7a by the press groove 6c and through hole 6b, respectively. Therefore, the core wire 7a does not require any solder or press work for avoiding scattering, thereby reducing the number of work processes and the manufacturing cost. 
     When welding the core wire 7a to the wire harness on the welding portion 5b, it is unnecessary to hold the wire harness by using human hands, fastening members, or the like, thereby achieving an easy assembly operation and a reliable welding. 
     As shown in FIG. 3, each of electric wires 4a of the flexible cable 4 is connected to each terminal piece 5a, respectively. The other end of the flexible cable 4 is connected to the connector 10. 
     The supporter 6 provided with the flexible cable 4 and the wire harness 7 is mounted such that the connector 9 is passed through the mounting hole 2b of the rotor housing 2 from the lower side in FIG. 1. The cover 8 is mounted such that contact holes 8a of the cover 8 are fitted with the claws 2a provided on the rotor housing 2, respectively. The cover 8 is then fixed on the supporter 6 by using screws. By this arrangement, both the cover 8 and the supporter 6 grip the periphery portion of the mounting holes 2b and are fixed on the rotor housing 2. 
     The flexible cable 4 is received within the case composed of the stator housing 1 and the rotor housing 2, and the rotor housing 2 and the connector 9 are attached on the steering side of the rotary connector apparatus. The stator housing 1 and the connector 10 are attached on the automobile body side of the rotary connector apparatus. 
     Referring now to FIG. 6, a second embodiment of the present invention will be described hereinafter. In FIG. 6, the same components which are present in the first embodiment are denoted by the same numerals as in the first embodiment. In the second embodiment shown in FIG. 6, a wire harness 11 is used which is similar to the wire harness 7 of the first embodiment, except that the coating film 7d at the end point of the wire harness 7 is removed. 
     The wire harness 11 has only an exposed core wire 11b at the end point of the coating film 11a. The coating film 11a is held by being fitted into the press groove 6c. The end point of the exposed core wire 11b is inserted into the through hole 6b. The portion of the exposed core wire 11b rearward of the through hole 6b is welded onto the welding portion 5b. Moreover, the supporter 6, including the through hole 6b, is the same as that shown in FIGS. 4 and 5 of the first embodiment. The structural formation and size of the through hole 6b is not limited to the specific structure shown in the drawings, as long as the through hole 6b allows the insertion of the end point of the core wire 11b. 
     Since the end point of the core wire 11b of the wire harness 11 is held by the through hole 6b, the multiple strands of the core wire 11b on the welding portion 5b are prevented from scattering during assembly. Therefore, it is unnecessary to use a solder, a press work, or the like to hold the multiple strands of the core wire 11b together. When welding the core wire 11b on the welding portion 5b, the end point of the core wire 11b is inserted into the through hole 6b, and the coating film 11a is pressed into the press groove 6c. Therefore, the core wire 11b is guided to the center position of the welding portion 5b, and both sides of the core wire 11b are held. It is unnecessary upon welding the core wire 11b on the welding portion 5b to hold the wire harness 11 by using human hands, fastening members, or the like, thereby simplifying a welding operation. Moreover, the area in which the core wire 11b contacts the terminal 5 becomes large, which results in a reliable electrical connection. 
     Referring now to FIG. 7, a third embodiment of the present invention will be described hereinafter. In FIG. 7, the same components which are present in the first and second embodiments are denoted by the same numerals as in the first and second embodiments. According to the third embodiment shown in FIG. 7, the core wire 11b of the wire harness 11 is held by a through hole 13a formed in the terminal 13. 
     The wire harness 11 of the third embodiment is the same as that of the second embodiment as shown in FIG. 6. The coating film 11a of the wire harness 11 is inserted into the press groove 12b of the supporter 12. The end point of the core wire 11b is inserted into the through hole 13a. A portion of the core wire 11b rearward of the through hole 13a is welded onto the welding portion 13b of the terminal 13. 
     In the supporter 12 shown in FIG. 7, the welding portion 13b of the terminal 13 is disposed in the recess portion 12a, and the through hole 13a for holding the exposed end point of the core wire 11b is formed in the terminal 13. The press groove 12bis a groove with a semi-circle section into which the coating film 11a can be inserted with pressure. The press groove 12b is adjacent to the recess portion 12a. 
     The terminal 13 has the welding portion 13b mounted with a through hole 13a in the recess portion 12a of the supporter 12. The terminal 13 is inserted into the supporter 12 by using an insert molding method. The exposed core wire 11b is passed through the circular through hole 13a and is mounted at the end portion of the welding portion 13b in the recess portion 12b. The structural formation and size of the through hole 13a is not limited to the specific structure shown in the drawings, as long as the through hole 13a allows the end point of the core wire 11b to be inserted therein. The supporter 12 includes the press groove 12b for holding the coating film 11a and the recess portion 12a for positioning the core wire 11b. The terminal 13 is formed within the supporter 12 by an insertion molding method or the like. 
     According to the third embodiment of the present invention, the wire harness 11 holds the end point of the core wire 11b by utilizing the through hole 13a formed in the terminal 13. Therefore, the multiple strands of the exposed core wire 11b on the welding portion 13b are prevented from scattering without using a solder, a press work, or the like. When the core wire 11b of the wire harness 11 is welded to the welding portion 13b of the terminal 13, the end point of the core wire 11b is inserted into or held by the through hole 13a, and the coating film 11a is inserted into the press groove 12b. Therefore, the core wire 11b is guided at the center position of the welding portion 5b, and both sides of the core wire 11b disposed on the welding portion 13b are held. The core wire 11b can be welded on the welding portion 13b without the use of human hands, a fastening member, or the like, to hold the wire harness 11, thereby achieving an easy welding operation. Moreover, since the core wire 11b is inserted into the through hole 13a, the area of the core wire 11b in contact with the terminal 13 becomes large, thereby achieving a reliable electric welding. 
     The rotary connector apparatus of the present invention having the structure described above has the following effects. 
     (1) The supporter is formed with a through hole into which the core wire at the end point of the wire harness or the coating film are inserted. Therefore, the wire harness may be guided and held at a desired position using the through hole, and upon welding the wire harness to the terminal, it is unnecessary to hold the wire harness by using human hands, a fastening member, or the like, thereby achieving an easy welding operation and a reliable welding. 
     (2) A recess portion is formed in the supporter, the welding portion of the terminal is exposed in the recess portion, and the through hole into which the end point of the core wire is inserted and supported is formed in the supporter. Therefore, the multiple strands of the core wire are prevented from scattering, and the core wire does not require any additional holding when welding the core wire onto the welding portion, thereby reducing the number of work processes and the manufacturing cost. 
     (3) The through hole is formed at the position adjacent to the terminal. Therefore, the core wire is guided to a desired position and fixed. 
     (4) The through hole is formed on the terminal inserted into the supporter. Therefore, when the core wire of the wire harness is welded onto the welding portion, the end point of the core wire is inserted into the through hole, and the core wire may be held at a desired position on the welding portion, thereby resulting in an easy welding operation. Moreover, by inserting the core wire into the through hole, the area in which the core wire is electrically connected to the terminal becomes large, thereby enabling a reliable electric connection. 
     (5) The supporter is provided with the press groove into which the coating film is inserted or fitted at the portion adjacent to the recess portion. Therefore, it is possible to hold both sides of the core wire to be welded on the terminal, and to guide and fix the core wire at the center position of the welding portion, thereby enabling an easy welding operation. 
     It will be appreciated that the present invention is not limited to the exact construction that has been described above and illustrated in the accompanying drawings, and that various modifications and changes can be made without departing from the scope and spirit thereof. It is intended that the scope of the invention only be limited by the appended claims.