Impact absorbing steering apparatus

Abstract: In a shock absorbing steering, a bracket (7) rotatably fixed to a clamp (9), attached to a vehicle body is linked to a column jacket (1) by means of welding and an enclosing body (13) is extended in a space between the bracket (7) and clamp (9) so as to enclose the upper surface of the bracket (7), thus preventing foreign matter from invading the inside of the bracket. In addition, the bracket (7) includes a front wall (7a) to which the column jacket (1) is perpendicularly fixed, curling portions (7b) formed on both side ends of the front wall (7a), rollers (8) inserted into the corresponding curling portions, and side walls (7c) extended from the curling portions in parallel to the column jacket, and cut-out portions (7d) formed on a portion of the bracket below the curling portions. Furthermore, the bracket (7) includes projection portions (11) located below the cut-out portions (7d) and engaged by step portions of the clamp, the clamp (9) including pawl portions (10) engaging bottom and front portions. Therefore, even if spot welded portions (12) connecting the bracket and clamp are snapped due in the secondary collision, the projection portion and pawl portions serve to block the shock energy from being transmitted and prevent the bracket from disengaging from the clamp. Shock energy is absorbed when the cut-out portions (7d) are torn off.

Description: The present invention relates to a structure of an impact absorbing steering apparatus for an automotive vehicle. A steering apparatus generally includes a steering column having a steering bracket removably supporting a column jacket from a vehicle body, the column jacket being extendable and contractable in its axial direction so that a vehicle occupant can be protected from a secondary collision against the steering apparatus after collision with a moving or stationary obstacle. JP-U-53-26030 discloses a bracket that has a U-shaped groove opened toward an upper end portion thereof and is fixed to the vehicle body by means of a bolt fitted into the groove. Therefore, if impact is received by the column jacket from the occupant, the bracket slides downward leaving the bolt. However, it is difficult for the column jacket to smoothly detach from the vehicle body in a case where shock from a direction other than the axial direction of the column is applied to the column jacket. A Japanese Utility Model Registration First Publication No. Showa 52-55535 published on April 20, 1977 (filed on December 20, 1975) exemplifies a previously proposed structure of an impact absorbing steering apparatus in which a cut out portion in a substantially horizontal direction intersecting with the column jacket is previously formed on the bracket so that shock energy may be absorbed by tearing off the cut out portion when an excessive force is applied to the column jacket. Since secondary collision generates a force which pushes from the upper end portion of the column jacket toward the front of the vehicle body, the bracket linking the column jacket is supported on a clamp fixed to the vehicle body with merely a plurality of spot welded portions. However, in the previously proposed structure of the steering apparatus disclosed in the above-identified Japanese Utility Model Registration First Publication, the bracket may be detached from the clamp if the spot welded portions are snapped due to shock upon vehicle collision. At this time, the shock absorbing effect induced by the tearing off of the cut out portion is pre-empted and therefore of no benefit to the vehicle driver. On the other hand, JP-A-1-249571 discloses a steering apparatus in which the bracket includes a front wall to which the column jacket is perpendicularly fixed, a curl portion formed on both side ends of the front wall by bending thereof at a predetermined curvature, a roller inserted into the curl portion, both side portions extended in parallel to the column jacket from the curl portion, and cut out portions formed respectively on the both side portions. The bracket is fixed on a clamp fixed to the vehicle body. In a case where impact is received by the column jacket in the axial direction, the bracket generates curling and ripping so as to absorb the shock energy. However, since in the above previously proposed steering apparatus a steering shaft and its universal joints are arranged within the jacket enclosing the clamp and bracket, the rotation of the steering shaft could be blocked or canceled by foreign matter (,e.g., a bolt or coin placed on an instrument panel) slipping into the inside of the bracket or dropped thereinto. Also, in the steering column in which curling and ripping are generated, foreign matter dropped into the bracket as described above could inhibit the curling and ripping action so that the shock energy cannot be absorbed. DE-A-23 65 063, on which the preamble of claim 1 is based, discloses with reference to Figs. 5 and 8 a structure that has a pair of clamp portions fixed to a vehicle body; a bracket body integral with the clamp portions and having a wall portion with an opening in which a column jacket is mounted; and a plate-like reinforcing body extending across the top of the bracket body between the clamp portions. It is an object of the present invention to provide a structure of a steering apparatus which assures absorption of shock energy when a secondary collision occurs and which can suitably prevent foreign matter from being introduced thereinto. The invention provides a structure for a steering apparatus applicable to a vehicle, comprising: a clamp portion arranged to be attached to a predetermined part of a vehicle body; a bracket body fixed to the clamp portion and having a wall portion through which a column jacket, in which a steering shaft is coaxially housed, is linked, said bracket body being substantially C-shaped in horizontal cross section, and said bracket body including side walls having spot welded portions respectively so as to link to the clamp portion; and an enclosing body enclosing an entire upper surface of the bracket body, characterised in that said bracket body includes a wall portion including curl portions located adjacent to the side walls, into which rollers are inserted, and that said enclosing body has leg-like formed portions at one end thereof inserted into the lower portion of a stop portion of the column jacket, and includes holes at the other end thereof through which the rollers are inserted into the curl portions. Two forms of steering apparatus incorporating structures according to the invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a partially sectioned side view of a structure of a steering apparatus in a first preferred embodiment according to the present invention. Fig. 2 is an elevation of an essential part of the steering apparatus shown in Fig. 1. Fig. 3 is a partially sectioned side view of the structure of the steering apparatus in a second preferred embodiment according to the present invention. Fig. 4 is an elevation of the essential part of the steering apparatus shown in Fig. 3. Fig. 5 is a partially omitted cross sectional view cut away along a line A - A of Fig. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS : Reference will hereinafter be made to the drawings in order to facilitate a better understanding of the present invention. Figs. 1 and 2 show a first preferred embodiment of a structure of a steering apparatus according to the present invention. In Figs. 1 and 2, an upper jacket 1 and lower jacket 2 are engaged so as to enable contraction in an axial direction via a pressure contact portion 3, the jackets 1 and 2 being axially engaged with an upper shaft 4 and lower shaft 5 so as to enable contraction, the construction having a substantially elliptical cross section. A lower end of the lower shaft 5 is linked with an universal joint 6. A C-shaped bracket 7 is linked to the upper jacket 1 by means of welding with the upper jacket 1 perpendicularly intersecting the front wall 7a. The front wall 7a of the bracket 7 contacts both side portions on which curl portions 7b, 7b are formed. Side portions 7c, 7c are formed extending parallel to each other along the upper jacket 1 and cut out portions 7d, 7d (refer to Fig. 1) are formed on the both side portions 7c, 7c. It is noted that rollers 8, 8 in flat head pin forms are inserted under pressure into the curl portions 7b, 7b. The bracket 7 has its front end portion engaged with a clamp 9 fixed to a vehicle body via a pawl portion 10 bent in a key form so as to project toward the inner portion of the bracket 7. The side portions 7c, 7c engage the clamp 9 via another pawl portion 11. In addition, the bracket 7 is fixed to the clamp 9 via spot welded portions 12, 12. The clamp 9 is fixed to the vehicle body so as not to disengage from the vehicle body. As shown in Fig. 2, the bracket 7 is covered with a enclosing body 13 on the upper surface thereof. The front end portions 13a, 13a of the enclosing body 13 project in leg-like forms and are disposed so as to be bent wholly upward with the front end portions 13a, 13a of the enclosing body 13 inserted into the lower portion of the projection stop portion 14 of the column jacket. Holes 13b, 13b are fitted into the corner at the rear end thereof so as to insert the rollers 8, 8. The enclosing body 13 requires a soft and flexible material, a thin metal or a plastic such as chloreoethylene, for example. An operation of the first preferred embodiment will be described below. When a so-called secondary collision occurs, the weight of the vehicle driver is imposed on the steering wheel and the upper column jacket and upper shaft are moved downward in the axial direction. At this time, the curl portions 7b, 7b formed on the front walls 7a of the bracket 7 by which the movement of the clamp 1 is blocked absorb the energy, curling via the rollers 8, 8 without change in curvature. Then, at the final stage, the cut out portions 7d, 7d are finally ripped. When the bracket is broken, the shock energy can be absorbed. In addition, since the bracket 7 is completely covered with the enclosing body 13, foreign matter is blocked from the inside of the bracket 7 so that ill effects therefrom on the shock absorbing structure can completely be prevented. A hole 13b of the enclosing body 13 acts as a holder holding the roller 8. As a whole, the roller 8 is disposed so as to bend upward, the bracket 7 itself serves to act as a so-called play killer, such that, when the vehicle runs the bracket will not vibrate. Hence, abnormal sound can be prevented. In the first preferred embodiment, the same effect can be generated even if the present invention is applied to a so-called tilt type steering column in which the bracket of a flat C-shaped type is rotatably pivoted to the clamp. Figs. 3 to 5 show a second preferred embodiment of the steering apparatus of the shock absorbing type according to the present invention. In the second preferred embodiment, the projection portions 7f, 7f are penetrated thorough elongated holes 9b, 9b of step portions 9a, 9a formed on the clamp 9, projected toward the external side (as shown in Fig. 5), and linked to the clamp 9 by means of spot welded portions 12, 12. In the second preferred embodiment, when the weight of the vehicle driver is imposed on the steering wheel so that the upper jacket 1 and upper shaft 4 receive the weight in the arrow marked direction of Fig. 3, the curl portions 7b, 7b of the front wall 7a of the bracket 7, the movement of which is blocked by the clamp 1, absorbs the energy, curling via the rollers 8, 8 without change in curvature. Finally, with the cut-out portions 7d, 7d ripped, the bracket is broken so that the shock energy is absorbed. At this time, the bracket 7 receives the rotating force in the arrow-marked direction with the pawl portions 10, 10 as a fulcrum. Then, since the projection portions 7f, 7f engage the clamp 9 and engage the pawl portions 11, 11, they serve to block rotational force. The other structure and operation are substantially the same as those in the first preferred embodiment. As described hereinabove, since, in the steering apparatus according to the present invention, the enclosing body is installed so as to enclose the upper surface area of the bracket, the bracket being a flat C-shaped column jacket in which the steering shaft is coaxially housed, a dangerous state such that foreign matter is invaded into the bracket or inserted thereinto can be prevented. In addition, influence on the curling and ripping action of the bracket itself, or on the rotation of the steering shaft can be prevented. In addition, since the projection portions are installed on the lower part of the cut-out portions of the bracket and its projection portion is penetrated and engaged through the clamp and the pawl portions engaging the bottom portion and front portion of the bracket are formed on the clamp, the projection portions penetrating through the clamp prevent the spot welded portions from tearing off due to the shock of collision. Therefore, the bracket will not be separated from the clamp and the tearing-off effect of the cut-out portions is retained. It will fully be appreciated by those skilled in the art that the foregoing description is made in terms of the preferred embodiments and various changes and modifications may be made without departing from the scope of the present invention which is to be defined by the appended claims.

Claims: A structure for a steering apparatus applicable to a vehicle, comprising: a clamp portion (9) arranged to be attached to a predetermined part of a vehicle body; a bracket body (7) fixed to the clamp portion and having a wall portion (7a) through which a column jacket (1), in which a steering shaft (4, 5) is coaxially housed, is linked, said bracket body being substantially C-shaped in horizontal cross section, and said bracket body (7) including side walls having spot welded portions respectively so as to link to the clamp portion; and an enclosing body (13) enclosing an upper surface of the bracket body, characterised in that said bracket body (7) includes a wall portion (7a) including curl portions (7b, 7b) located adjacent to the side walls, into which rollers (8, 8) are inserted, and that said enclosing body (13) has leg-like formed portions (13a) at one end thereof inserted into the lower portion of a stop portion (14) of the column jacket, and includes holes (13b) at the other end thereof through which the rollers (8) are inserted into the curl portions (7b). A structure as set forth in claim 1, characterised in that said enclosing body (13) is of a soft, flexible material. A structure as set forth in claim 2, characterised in that said soft, flexible material is chloroethylene. A structure as set forth in claim 3, characterised in that each of said rollers (8) comprises a flat head type pin. A structure as set forth in claim 4, characterised in that said clamp portion (9) includes pawl portions (11, 11) engaged with the side walls of the bracket body. A structure as set forth in claim 5, characterised in that said side walls of the bracket body (7) includes: cut out portions (7d, 7d) and projection portions (7f, 7f) which are placed below the corresponding spot welded portions and below the cut out portions (7d, 7d), said projection portions (7f, 7f) penetrating through elongate holes of step portions (9a, 9a) formed on the clamp portion.

Inventors: MARUYAMA TOMOYUKI C O FUJI KIK, SHIMIZU YOSHIYUKI C O FUJI KIK, MARUYAMA, TOMOYUKI, SHIMIZU, YOSHIYUKI, MARUYAMA, TOMOYUKI, C/O FUJI KIKO COMPANY LTD., SHIMIZU, YOSHIYUKI, C/O FUJI KIKO COMPANY LTD.
Applicants: FUJI KIKO KK, FUJI KIKO COMPANY LIMITED
Application year: 1990
Main classification: B62D1
IPC codes: B62D1