Steering device and vehicle wheel mounting module including the same
A steering device, including: a steering knuckle rotatably holding a wheel; an electric motor and a speed reducer configured to decelerate rotation of the electric motor, the electric motor and the speed reducer being fixed to a suspension arm; and a joint through which the steering knuckle is supported by the suspension arm in a state in which a kingpin axis is allowed to incline with respect to the suspension arm, the joint coupling the steering knuckle and an output shaft of the speed reducer such that the steering knuckle pivots about the kingpin axis by an operation of the electric motor.
1. A wheel mounting module for a vehicle, comprising:
a base to be installed on a body of the vehicle;
a first suspension arm, a proximal end portion of which is pivotally supported by the base;
a steering device comprising:
(a) a steering knuckle rotatably holding a wheel,
(b) an electric motor and a speed reducer configured to decelerate rotation of the electric motor, the electric motor and the speed reducer being fixed to the first suspension arm, and
(c) a joint through which the steering knuckle is supported by the first suspension arm in a state in which a kingpin axis is allowed to incline with respect to the first suspension arm, the joint coupling the steering knuckle and an output shaft of the speed reducer such that the steering knuckle pivots about the kingpin axis by an operation of the electric motor;
a second suspension arm, a proximal end portion of which is pivotally supported by the base, the second suspension arm being coupled to the steering knuckle through another joint;
a suspension spring and a shock absorber disposed in parallel with each other, the suspension spring and the shock absorber coupling the base and one of the first suspension arm and the second suspension arm; and
a wheel drive unit disposed inside a rim of the wheel and including a drive motor for driving the wheel, a housing of the wheel drive unit functioning as the steering knuckle.
2. The wheel mounting module according to claim 1 , wherein the joint is a constant velocity joint.
3. The wheel mounting module according to claim 2 , wherein the constant velocity joint is a tripod constant velocity joint.
4. The wheel mounting module according to claim 1 , wherein the speed reducer comprises a speed reduction mechanism that comprises an input shaft disposed coaxially with the output shaft, and wherein the speed reduction mechanism has a reduction ratio of not less than 50, the reduction ratio being a ratio of a rotation speed of the input shaft to a rotation speed of the output shaft.
5. The wheel mounting module according to claim 4 , wherein the speed reduction mechanism is one from among a differential mechanism of an internally-meshing gear type and a harmonic gear mechanism.