| CPC B62D 5/0448 (2013.01) [B62D 5/0445 (2013.01); F16H 25/2214 (2013.01); F16H 25/2472 (2013.01); B62D 5/0403 (2013.01); B62D 5/0424 (2013.01)] | 10 Claims |
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1. A steering device for driving steered wheels of an automobile, the steering device comprising:
a housing internally including a turning shaft accommodating space, a speed reducer accommodating space, an outer race abutting portion, a lock nut fastening female thread portion, and a lock nut abutting portion;
a turning shaft, which is provided in the turning shaft accommodating space, and includes a turning shaft main body having a bar-like shape and a turning shaft ball screw groove formed on an outer peripheral side of the turning shaft main body;
a turning nut, which is provided in the speed reducer accommodating space, includes a nut main body having a tubular shape, a nut ball screw groove formed on an inner peripheral side of the nut main body, and an inner race groove formed on an outer peripheral side of the nut main body, and is threadably engaged with an outer periphery of the turning shaft;
a plurality of circulating balls, which are provided between the turning shaft ball screw groove and the nut ball screw groove, and are configured to transmit a rotational force of the turning nut to the turning shaft;
a ball bearing, which is provided in the speed reducer accommodating space, and includes an outer race including an outer race main body having a tubular shape and an outer race groove formed on an inner peripheral side of the outer race main body, and balls provided between the inner race groove formed on the outer peripheral side of the nut main body and the outer race groove;
an electric actuator configured to apply a rotational force to the turning nut; and
a lock nut, which is provided in the speed reducer accommodating space, and includes a lock nut main body, a lock nut fastening male thread portion, a loosening prevention protruding portion, and a lock nut recessed portion,
wherein the lock nut main body is provided in such a manner that the outer race is sandwiched between the lock nut main body and the outer race abutting portion in a direction of an axis of the turning shaft,
wherein the lock nut fastening male thread portion is formed on an outer peripheral side of the lock nut main body so as to be threadably engageable with the lock nut fastening female thread portion,
wherein the loosening prevention protruding portion is formed to protrude from the lock nut main body in the direction of the axis of the turning shaft, and, when the lock nut is fastened to the housing, the loosening prevention protruding portion is contactable with the lock nut abutting portion so as to generate a fastening force for the lock nut, and
wherein the lock nut recessed portion is formed in the loosening prevention protruding portion so that a thickness of the loosening prevention protruding portion in a radial direction orthogonal to the axis of the turning shaft becomes smaller than a thickness of a region of the loosening prevention protruding portion, which is adjacent to the lock nut recessed portion, or is formed in the lock nut main body so that a thickness of the lock nut main body in the direction of the axis of the turning shaft becomes smaller than a thickness of a region of the lock nut main body, which is adjacent to the lock nut recessed portion.
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