Signal transmission device for steering column

Abstract: The signal transmission device for a steering 46 is structured such that an inner cylinder formed as a rotating member is disposed inside and concentrically with an outer cylinder 47 formed as a fixed member, a spirally arranged cable is stored in an annular storage chamber formed between the outer cylinder 47 and inner cylinder, and one end 50a of the cable 50 is supported in the outer cylinder 47, whereas the other end 50b of the cable 50 is supported in the inner cylinder. In the signal transmission device for a steering 46, a canceler portion 57 is formed integrally in the upper cover 53 of the inner cylinder. The canceler portion 57, as the steering is rotated and returned, can be contacted with a return portion 59 formed in a turn signal cancel mechanism to thereby return a turn signal lever 43 to its neutral position.

Description: BACKGROUND OF THE INVENTION The present invention relates to a signal transmission device for a steering which is used to electrically connect an auxiliary device provided on the steering side to a wiring harness which is provided on the vehicle body side. As a signal transmission device for a steering which supplies electricity to an auxiliary device provided on a rotating steering, there is also available a signal transmission device for a steering which employs a sliding contact system. However, for example, in an air bag system to be mounted onto a steering, sliding contacts used can be cut off instantaneously, and such sliding contact instantaneous cutoff phenomenon is fatal to the air bag system. For this reason, there is employed a cable type of electric connecting device (SRC; Steering Roller Connector) which is high in reliability. Here, Fig. 1 is an exploded perspective view of a conventional column and Fig. 2 is a section view of the column shown in Fig. 1 taken along the axial direction of a steering. An SRC 1 comprises an outer cylinder 3 which is a fixed member, and an inner cylinder 5 which is a rotating member and is coaxial with the outer cylinder 3. Between the outer cylinder 3 and inner cylinder 5, there is formed an annular storage chamber in which a cable 6 is stored in a spiral manner. One end of the cable 6 is guided out from the outer cylinder 3 and is connected to a wiring harness provided on the vehicle body side, while the other end of the cable 6 is guided out from the inner cylinder 5 and is connected to an auxiliary device (such as a horn switch, a steering switch, a squib provided in an inflator, or the like). The SRC 1 can be fixed to a column 9 in such a manner that a fixing portion 7 provided on the outer periphery of the outer cylinder 3 is fixed to a screw hole 11 formed in the column 9. The column 9 includes a pair of connector storage portions 13 which are respectively formed on the two side surfaces thereof; and, a lever unit, that is, a turn signal head lamp switch lever (a turn signal lever) 15 or a wiper control switch 17 is mounted into the corresponding one of connector storage portions 13. Also, a canceler 19 is assembled to the column 9. The canceler 19 includes an engaging projection 27 on the upper surface thereof and, in order to prevent its relative rotation to the SRC 1, the engaging projection 27 is engaged with the lower surface of the inner cylinder 5 of the SRC 1. Also, the canceler 19 can be rotated integrally with the steering and thus, if the canceler 19 is rotated integrally with steering, then it not only transmits the rotation of the steering to the inner cylinder 5 of the SRC 1 but also brings a canceler portion 23 into contact with a return portion (a cancel cam) 25 provided in a turn signal cancel mechanism (not shown) to thereby return or cancel the turn signal lever 15 to its neutral position. Between the canceler 19 and a base plate 29 provided in the column 9, there is interposed a spring 31 which is used to energize the canceler 19 toward the SRC 1. Due to use of this structure, even when the SRC 1 is mounted at a position where the engaging projection 27 is not engaged, the canceler 19 can be moved in the steering axial direction against the energizing force of the spring 31, thereby being able to prevent itself against breakage. However, in the above-mentioned conventional column structure, since the SRC 1 is disposed on the column 9, the canceler 19 is disposed on the lower surface of the column 9 in such a manner that it can be moved in the steering axial direction, and the spring 31 is used to energize the canceler 19 toward the SRC 1, there is required a wide space which extends in the steering axial direction and is used to store these component parts, which not only increases the size of the column structure but also increases the number of parts to be disposed in the steering axial direction to thereby increase the number of man-hour for assembling. Also, when the SRC 1 is stored within the column 9, because of the limited space, the cancel system must be replaced with an electronic system, which further increases the number of parts required as well as the cost of the whole device. Further, since the spring load of the spring 31 is applied to the eliding surface of the spring 31, there increases a friction loss in rotation, which in turn degrades the operating feeling of the steering. EP-A-0 520 503 according to the precharacterizing part of claim 1 discloses a signal transmission device incorporated within a steering column. An outer cylinder is fixedly mounted on said column, while an inner cylinder is arranged to be rotated in unison with a steering shaft of said steering. A spirally arranged flat cable is contained in an annular chamber defined between said outer cylinder and said inner cylinder. One end of said cable is connected to male terminals and bus bars arranged on said inner cylinder, while the other end of said cable includes male terminals and bus bars for connecting with mating connectors of electrical devices. SUMMARY OF THE INVENTION The present invention aims at eliminating the drawbacks found in the above-mentioned conventional signal transmission device for a steering. Accordingly, it is an object of the invention to provide a signal transmission device for a steering which can eliminate the need for provision of a movably structured canceler using a spring and can structure a compact column with the reduced number of parts and at a low cost. In attaining the above object, according to the invention, there is provided a signal transmission device for a steering comprising: a column; a turn signal lever mounted on the column and movable within a range containing its neutral position, the turn signal lever having a turn signal cancel mechanism with a return portion; an outer cylinder fixedly mounted on the column; and an inner cylinder rotatably disposed inside and concentrically with the outer cylinder; and a spirally arranged cable stored in an annular storage chamber defined between the outer cylinder and the inner cylinder, one end of the cable being supported in the outer cylinder, the other end of the cable being supported in the inner cylinder; wherein the inner cylinder is provided with an upper cover having a canceler portion which is contactable with the return portion so as to return the turn signal lever to its neutral position. In the above-mentioned signal transmission device for a steering, the inner cylinder, the upper cover and the canceler portion are preferably formed integrally. In addition, the signal transmission device for a steering may also be structured such that an auxiliary device connecting connector is disposed in the upper cover and the other end of the cable is connected to the present auxiliary device connecting connector. Also, the signal transmission device for a steering may also be structured such that a steering wheel mounting contact surface is formed in the other portion of the upper surface of the cover than the canceler portion, and either of the other end of the cable or the auxiliary device connecting connector is fixed to the upper surface of the canceler portion. According to the signal transmission device for a steering in the above-mentioned manner, since there is employed the upper cover which can be rotated integrally with the steering and the canceler portion is integrally formed in the upper cover, not only the original function of a signal transmission device for a steering, that is, supply of electricity to the steering can be fulfilled but also the canceler portion can be contacted with the return portion of the turn signal cancel mechanism to thereby return the turn signal lever to its neutral position. In addition, according to the signal transmission device for a steering structured such that the auxiliary device connecting connector is disposed on the upper cover, there can be eliminated the need for provision of a wiring harness, which makes it possible to connect the auxiliary device connecting connector directly to the auxiliary device terminal provided on the steering side. Also, according to the signal transmission device for a steering structured such that the steering wheel mounting contact surface is formed in the other portion of the upper surface of the upper cover than the canceler portion, the steering wheel can be mounted onto the upper surface of the upper cover, so that the mounting height of the steering wheel can be lowered by an amount equivalent to the canceler portion. Further, according to the signal transmission device for a steering structured such that the cable is stored in the annular storage chamber of the column, the signal transmission device for a steering can be assembled by using part of the column in common, which eliminates the need for provision of the outer cylinder. Still further, according to the signal transmission device for a steering structured such that the connector storage portion is formed integrally in the outer cylinder, simply by assembling the signal transmission device for a steering, the column can be structured. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an exploded perspective view of a conventional column; Fig. 2 is a section view of the column shown in Fig. 8, taken along the axial direction of a steering shaft; Fig. 3 is a perspective view of a first embodiment of a signal transmission device for a steering according to the invention, in which it is shown together with a column; Fig. 4 is a partially sectional view of the signal transmission device for a steering shown in Fig. 3, showing a state thereof in which it is assembled to the column; Fig. 5 is a perspective view of a second embodiment of a signal transmission device for a steering according to the invention; Fig. 6 is a perspective view of a third embodiment of a signal transmission device for a steering according to the invention; Fig. 7 is a perspective view of a modification of the signal transmission device for a steering shown in Fig. 6; and Fig. 8 is an exploded perspective view of a fourth embodiment of a signal transmission device for a steering according to the invention, in which it is shown together with a column. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, description will be given below in detail of preferred embodiments of a signal transmission device for a steering according to the invention with reference to the accompanying drawings. Fig. 3 is a perspective view of a first embodiment of a signal transmission device for a steering according to the invention, which is shown together with a column; and, Fig. 4 is a partially sectional view of the signal transmission device for a steering shown in Fig. 3, illustrating a state thereof in which it is assembled to the column. In particular, a column 41 includes a pair of connector storage portions 42 respectively formed on the two side surfaces thereof, while each of the connector storage portions 42 is arranged such that it can store therein a connector portion 43a or 44a formed in the base end portion of a lever unit, that is, a turn signal head lamp switch lever (turn signal lever) 43 or a wiper control switch lever 44. The column 41 also includes an annular recessed portion 45 having an open upper surface in such a manner that the annular recessed portion 45 is coaxial with a steering shaft (not shown), while the annular recessed portion 45 is used to store and fix a signal transmission device for a steering (SRC) 46. The SRC 46 includes an outer cylinder (that is, an under cover) 47 and an inner cylinder (that is, a rotator) 49 which can be rotated inside the under cover 47. Between the under cover 47 and rotator 49, there is stored a cable 50 in a spiral manner. In the under cover 47, there is formed a guide portion 51 which is used to pull out one end 50a of a cable to the outside. The rotator 49 is mounted on the outer periphery of the steering shaft in such a manner that it is prevented from rotating with respect to the steering shaft. The rotator 49 includes a disk-shaped upper cover 53 which is formed integrally with the rotator 49 and can be rotated while covering the upper surface opening of the under cover 47. The upper cover 53 includes an upper surface 53a and a platform plate portion 55 which is formed integrally with and projected from the upper surface 53a. The upper surface of the platform plate portion 55 is used as a contact surface 55a for mounting a steering wheel. On the contact surface 55a of the platform plate portion 55, there are erected a pair of bosses 56 which are respectively used to position a steering wheel. The platform plate portion 55 includes a pressure surface (that is, a canceler portion) 57 which is formed by removing part of the circumferential portion of the platform plate portion 55 in such a manner that it is perpendicular to the upper surface 53a and stands up in the radial direction of the upper cover 53. If the canceler 57 is rotated integrally with the upper cover 53 with the return rotation of the steering, then it is butted against a return portion (that is, a cancel cam) 59 provided in a turn signal cancel mechanism to thereby return the turn signal lever 43 to its neutral position. Onto the upper surface of the upper cover 53, there is guided the other end 50b of the cable; and, the other end 50b of the cable is connected to a squib terminal (not shown) disposed on the steering when the steering wheel is mounted onto the steering shaft. Also, the column 41 includes a collective connector 61 formed integrally therewith; and, electric circuits respectively for the turn signal lever 43, wiper control switch lever 44, cable end 50a drawn out from the guide portion 51 of the under cover 47, a sensor and the like are collectively connected to the collective connector 61. According to the thus structured SRC 46, since there is used the upper cover 53 rotatable integrally with the steering and the canceler portion 57 is formed integrally with the upper cover 53, the SRC 46 not only can fulfil its original function, that is, can supply electricity to the steering, but also can come into contact with the return portion 59 of the turn signal cancel mechanism to thereby return the turn signal lever 43 to its neutral position. This makes it possible not only to omit the movably structured canceler 19 (see Fig. 1) using the spring 31 (see Fig. 1) but also to assemble the column 41 to the SRC 46 with the reduced number of parts, in a compact assembly, and at an inexpensive cost. Next, description will be given below of a second embodiment of a signal transmission device for a steering according to the invention with reference to Fig. 5. In particular, Fig. 5 is a perspective view of the second embodiment of a signal transmission device for a steering according to the invention. By the way, in Fig. 5, the same parts or portions as those shown in Figs. 3 and 4 are given the same designations and thus the duplicated description thereof is omitted here. An SRC 71 according to the present embodiment includes an auxiliary device connecting connector 73 on the upper surface of the platform plate portion 55 in place of the above-mentioned cable 50b which is guided from the upper surface of the upper cover 53. The auxiliary device connecting connector 73 is connected to the other end of a cable built in the SRC 71 and is arranged such that, when the steering wheel is mounted onto the steering shaft, it can be fitted directly with an auxiliary device terminal (not shown) such as a squib or the like which is provided on the steering. According to the SRC 71, the auxiliary device connecting connector 73 is disposed on the upper cover 53 and is arranged such that it can be directly connected to the auxiliary device terminal on the steering side. Due to this, not only provision of a wiring harness can be eliminated but also the auxiliary device connecting connector 73 can be connected to the auxiliary device terminal at the same time when the steering is mounted, which can reduce the number of man-hour in operation. Next, description will be given below of a third embodiment of a signal transmission device for a steering according to the invention with reference to Figs. 6 and 7. In particular, Fig. 6 is a perspective view of the third embodiment of a signal transmission device for a steering according to the invention, and Fig. 7 is a perspective view of a modification of the signal transmission device for a steering shown in Fig. 6. By the way, in Figs. 6 and 7, the same parts or portions as those shown in Figs. 3 and 4 are given the same designations and thus the duplicated description thereof is omitted here. In an SRC 81 according to the present embodiment, the platform plate portion 55 except for the above-mentioned canceler portion 57 is omitted. In addition, a pair of bosses are erected directly on the upper surface 53a of the upper cover 53. Also, a take-out opening 83 (see Fig. 6) for taking out the other end 50b of the cable or an auxiliary device connecting connector 73 (see Fig. 7) is disposed on the upper surface 57a of the canceler portion 57. According to the present embodiment, the upper surface 53a of the upper cover 53 is used as a contact surface with the steering wheel, and the present contact surface is lower in height, by an amount corresponding to the platform plate portion 55 omitted, when compared with the above-mentioned SRC 46. By the way, in the present embodiment, the canceler portion 57 is projected upwardly from the lower surface of the steering wheel through a notch or the like formed in the lower surface of the steering wheel (not shown) and, in its projecting state, the canceler portion 57 can be contacted with the return portion 59 of the turn signal cancel mechanism to thereby return the turn signal lever 43 to its neutral position. According to the present SRC 81, the height of the column 41 in the steering shaft direction can be reduced by an amount equivalent to the omitted portion of the platform plate portion 55, which makes it possible to reduce the size of the column 41 further. Next, description will be given below of a fourth embodiment of a signal transmission device for a steering according to the invention with reference to Fig. 8. In particular, Fig. 8 is an exploded perspective view of the fourth embodiment of a signal transmission device for a steering according to the invention, together with a column. By the way, in Fig. 8, the same parts or portions as those shown in Figs. 3 and 4 are given the same designations and thus the duplicated description thereof is omitted here. In an SRC 91 according to the present embodiment, in the upper surface of a column 41, there is formed an annular recessed portion 93 coaxially with the steering shaft, while a cable 50 can be stored directly in the present annular recessed portion 93. The annular recessed portion 93 with the cable 50 stored therein is closed by a cover 97 including a steering shaft insertion hole 95. In the steering shaft insertion hole 95 of the cover 97, there is rotatably mounted an upper cover 53 which can be rotated integrally with the steering shaft. Similarly to the previously described SRC 46, the upper cover 53 is arranged such that the other end 50b of the cable 50 can be guided out from the upper surface thereof. According to the present SRC 91, since the annular recessed portion 93 for storing the cable 50 therein is formed in the column 41, the SRC 91 can be assembled using part of the column 41 in common, which eliminates the provision of the under cover 47 (see Fig. 4). This not only can reduce the number of parts but also can reduce the size of the column 41 by an amount equivalent to the under cover 47 omitted. As has been described heretofore in detail, according to the signal transmission device for a steering of the invention, since the canceler portion is formed integrally on the upper cover which can be rotated integrally with the steering, there can be omitted a conventional canceler of a movable structure using a spring, so that the column can be assembled to the present signal transmission device for a steering with the reduced number of parts, in a compact manner, and at an inexpensive cost. In addition, according to the signal transmission device for a steering structured such that the auxiliary device connecting connector is disposed on the upper cover, there can be eliminated the provision of a wiring harness, which makes it possible to connect the auxiliary device connecting connector to the auxiliary device terminal at the same time when the steering is mounted, thereby being able to reduce the number of man-hour in operation. Also, according to the signal transmission device for a steering structured such that the steering wheel mounting contact surface is formed in the other portion of the upper surface of the upper cover than the canceler portion, the steering wheel can be directly contacted with and mounted onto the upper surface of the upper cover, so that the mounting height of the steering wheel can be lowered by an amount equivalent to the canceler portion. While there has been described in connection with the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is aimed, therefore, to cover all such changes and modifications as fall within the scope of the invention as defined by the claims.

Claims: A signal transmission device for a steering comprising: a column (41); an outer cylinder (47) fixedly mounted on said column (41); an inner cylinder (49) rotatably disposed inside and concentrically with said outer cylinder (47); and a spirally arranged cable (50) stored in an annular storage chamber defined between said outer cylinder (47) and said inner cylinder (49), one end (50a) of said cable (50) being supported in said outer cylinder (47), the other end (50b) of said cable (50) being supported in said inner cylinder (49); characterized by a turn signal lever (43) mounted on said column (41) and movable within a range containing its neutral position, said turn signal lever (43) having a turn signal cancel mechanism with a return portion (59); wherein said inner cylinder (49) is provided with an upper cover (53) having a canceler portion (57) which is contactable with said return portion (59) so as to return said turn signal lever (43) to its neutral position. The signal transmission device for a steering as set forth in claim 1, wherein said inner cylinder (49), said upper cover (53) and said canceler portion (57) are formed integrally. The signal transmission device for a steering as set forth in claim 1, wherein an auxiliary device connecting connector (73) is formed in said upper cover (53), and said other end (50b) of said cable (50) is connected to said auxiliary device connecting connector (73). The signal transmission device for a steering as set forth in claim 1, wherein a steering wheel mounting contact surface (53a) is formed in the other portion of the upper surface of said cover (53) than said canceler portion (57), and said other end (50b) of said cable is provided to the upper surface (57a) of said canceler portion (57). The signal transmission device for a steering as set forth in claim 3, wherein a steering wheel mounting contact surface (53a) is formed in the other portion of the upper surface of said cover (53) than said canceler portion (57), and one of said other end of said cable and said auxiliary device connecting connector (73) is fixed to the upper surface (57a) of said canceler portion (57).

Inventors: KIKKAWA TOMOYOSHI, MASUDA HIROMI, KIKKAWA, TOMOYOSHI, MASUDA, HIROMI, Kikkawa, Tomoyoshi, c/o Yazaki Parts Co., Ltd., Masuda, Hiromi, c/o Yazaki Parts Co., Ltd.
Applicants: YAZAKI CORP, YAZAKI CORPORATION
Application year: 1998
Main classification: B60R16
IPC codes: H01H25, B60R16, B62D1, B60Q1, H01R35