Motor-driven position adjustment apparatus for steering wheel

• US 20060191368A1
• Filed: 02/17/2006
• Published: 08/31/2006
• Est. Priority Date: 02/17/2005
• Status: Active Grant

• Current Assignee: NSK Limited
• Original Assignee: NSK Limited
• Inventors: Sawada, Naoki, Fujiwara, Takeshi, Iwakawa, Masato, Shoda, Akihiro
• Granted Patent: US 7,410,190 B2
• Time in Patent Office: Days
• US Class Current: 74/495
• CPC Class Codes: B62D 1/181 with power actuated adjustment, e.g. with position memory
• CPC Class Codes: B62D 1/19 incorporating energy-absorbing arrangements, e.g. by being yieldable or collapsible shock absorbers using plastic deformation of members in general F16F7/12

Abstract

The present invention realizes a structure that can ensure silence during position adjustment of a steering wheel 8 by a feed screw mechanism 16, and that can achieve an improvement in the protection of a driver at the time of a collision accident.

A nut 17 being a driven member is mounted such that it can be detached from an inner column 3a constituting a steering column 1a, based on a shock load applied at the time of a secondary collision. Therefore, at the time of a secondary collision, a threaded rod 18 constituting the feed screw mechanism 16, does not have resistance with respect to displacement of the inner column 3a in the forward direction, and hence an improvement in the protection of the driver can be achieved. Moreover, since an integrated member can be used for the threaded rod 18, silence during the position adjustment can be ensured.

Claims

1. A motor-driven position adjustment apparatus for a steering wheel comprising:

a steering column with a steering shaft rotatably supported inside;

a driven member supported on a part of the steering column;

a driving member which is engaged with the driven member, and which displaces the driven member as it rotates; and

an electric motor for rotating and driving the driving member, and the steering column being displaced based on a relative displacement of the driving member and the driven member based on a current supplied to the electric motor, adjusting a position of a steering wheel supported on an end of the steering shaft,

wherein at least either one of the members of the driven member and the electric motor is mounted such that it can be detached from the steering column based on a shock load applied at the time of a collision.

2. A motor-driven position adjustment apparatus for a steering wheel according to claim 1, wherein at least either one of the members of the driven member and the electric motor, which is detached from the steering column at the time of a collision, is retained by a joining bracket, and the joining bracket is supported on the steering column by a joining member inserted through a mounting hole formed in a flange part thereof butted up against an outer peripheral surface of the steering column, and joined to the steering column, and the mounting hole is opened at one end of the flange part in a direction in which the joining member exits when the steering column is displaced due to a collision accident.

3. A motor-driven position adjustment apparatus for a steering wheel according to claim 2, wherein a low friction material is interposed between the flange part and an outer peripheral surface of the steering column.

4. A motor-driven position adjustment apparatus for a steering wheel according to claim 1, wherein at least either one of the members of the driven member and the electric motor, which is detached from the steering column at the time of a collision, is retained by a joining bracket and the joining bracket is supported on the outer periphery of the steering column via a joining member formed from a synthetic resin with a suitable strength such that it can be broken accompanying the impact of a collision accident.

5. A motor-driven position adjustment apparatus for a steering wheel according to claim 1, wherein the steering column is an inner column of a telescopic steering column whose overall length can be extended and contracted by inserting a front portion of the inner column arranged toward the rear into a rear portion of an outer column arranged toward the front, and the driven member is a nut which is supported on part of the inner column, exposed from the outer column, and that has a threaded hole in a direction parallel to the axial direction of the steering column, and the driving member is a threaded rod which is arranged parallel to the axial direction of the steering column, and a proximal end thereof is supported on part of the outer column such it can only be rotated freely, and a central part or a tip end thereof is screwed into the nut, and a position of the steering wheel in relation to the axial direction of the steering column can be adjusted freely by rotating the threaded rod using an electric motor supported on part of the outer column.

6. A motor-driven position adjustment apparatus for a steering wheel according to claim 5, wherein a sphere fixed to the nut is fitted inside a cylinder part provided on the joining bracket mounted on the outer periphery of the inner column such that it can be detached based on a shock load applied at the time of a collision, such that it can be displaced in the axial direction of the cylinder part.

7. A motor-driven position adjustment apparatus for a steering wheel comprising:

a steering column with a steering shaft rotatably supported inside;

a driven member joined to a part of the steering column;

a push-pull rod which is arranged in the axial direction of the steering column in a state where one end is joined to the driven member;

a driving member that is rotatably supported on the periphery of a part toward the other end of the push-pull rod, and that displaces the push-pull rod in the axial direction of the steering column as it rotates; and

an electric motor for rotating and driving the driving member, and the steering column being displaced based on a relative displacement of the driving member and the push-pull rod based on a current supplied to the electric motor, adjusting a position of a steering wheel supported on an end of the steering shaft,

wherein at least either one of a joined part between the push-pull rod and the driven member, and a joined part between the driven member and the steering column, can be separated based on a shock load applied at the time of a collision.

8. A motor-driven position adjustment apparatus for a steering wheel according to claim 7, wherein the separable joined part is constructed by fitting a pair of members to be joined, via an elastic deformable spacer.

9. A motor-driven position adjustment apparatus for a steering wheel according to claim 7, wherein the separable joined part is constructed by fitting a pair of members to be joined, via a spacer having a high coefficient of friction.

10. A motor-driven position adjustment apparatus for a steering wheel according to claim 8, wherein a spacer is interposed between an outer peripheral surface of a push-pull rod, and an inner peripheral surface of a retainer sleeve arranged on the periphery of the push-pull rod, and the retainer sleeve is joined to a driven member such that it can be displaced freely together with the driven member at the time of a collision accident.

11. A motor-driven position adjustment apparatus for a steering wheel according to claim 8, wherein an outer diameter of a part of the push-pull rod that is positioned on an inner diameter side of the spacer at a normal time, is made larger than an outer diameter of a part of the same that enters the inner diameter side of the spacer as a collision accident occurs.

12. A motor-driven position adjustment apparatus for a steering wheel according to claim 11, wherein two spacers whose inner diameters are different in a free state are provided at two positions in the axial direction on the periphery of the push-pull rod, and at normal times, a part of the push-pull rod whose outer diameter is large is located inside of the spacer whose inner diameter is large in a free state, and a part of the same whose outer diameter is small is located inside of the spacer whose inner diameter is small in the same state.

13. A motor-driven position adjustment apparatus for a steering wheel according to claim 7, wherein the separable joined part is constructed by joining a pair of members to be joined, using a joining member that breaks based on a shock load.