Patent ID: 11878740
Assignee: MAZDA MOTOR CORPORATION
Field: Mechanical elements (Mechanical engineering)
Classification: CPC B  F | IPC B  F

Claim 0:
1. A steering device configured to cause a pinion gear provided on a steering shaft to mesh with a rack gear of a steering rack with a tie rod swingably linked, thereby allowing the steering rack to reciprocate in an axial direction of the steering rack, the steering device comprising:
a rack housing having a hollow cylindrical shape, the steering rack being inserted in the rack housing in a row direction of rack gear teeth; and
a rack bushing attached to the rack housing to intervene between the steering rack and an inner circumferential surface of the rack housing, the rack bushing supporting the steering rack while allowing the steering rack to move in the row direction of the rack gear teeth, the rack bushing comprising:
a bushing main body having a hollow cylindrical shape, the steering rack being inserted into the bushing main body in the row direction of the rack gear teeth; and
an elastic member having an annular shape and arranged around an axis of the bushing main body so as to be located between the rack housing and the bushing main body;
the bushing main body comprising:
an inner circumferential surface surrounding the steering rack across a row of the rack gear teeth and supporting the steering rack, the inner circumferential surface being configured to allow the steering rack to reciprocate in the row direction of the rack gear teeth and to be displaced in a tooth depth direction of the rack gear teeth; and
an outer circumferential surface including an elastic member attachment groove formed along a circumferential direction of the bushing main body, the elastic member being attached to the elastic member attachment groove;
the inner circumferential surface comprising:
a first support surface and a second support surface each being flat and extending along the tooth depth direction of the rack gear teeth, the first support surface and the second support surface being located place opposite each other with the axis of the bushing main body therebetween and supporting the steering rack movable in the row direction of the rack gear teeth while allowing the steering rack to be displaced in the tooth depth direction of the rack gear teeth; and
a third support surface located, with respect to the circumferential direction of the bushing main body, between the first support surface and the second support surface, and facing an outer circumferential surface of the steering rack at a position on an opposite side of the axis of the bushing main body from the rack gear teeth and with a clearance in the tooth depth direction of the rack gear teeth between the outer circumferential surface of the steering rack and the third support surface; and

the elastic member attachment groove comprising:
a first groove section having a groove bottom located on and running along an arc which belongs to a first imaginary circle having a center lying on the axis of the bushing main body and which is located closer to the first support surface than the axis of the bushing main body; and
a second groove section having a groove bottom located on and running along an arc which belongs to a second imaginary circle defined as a shifted duplicate of the first imaginary circle toward the second support surface than the axis of the bushing main body,

wherein the first groove section is located closer to a place in which the steering rack is to push the rack bushing against the rack housing due to a reaction force from the tie rod when pushing the tie rod, than the axis of the bushing main body, and
wherein between the outer circumferential surface of the bushing main body and the inner circumferential surface of the rack housing, there is a space created by the elastic member embedded in the elastic member attachment groove depending on a protrusion amount of the elastic member above the outer circumferential surface of the bushing main body.