Steering control device

#This application claims priority to Japanese Patent Application No. 2020-039935 filed on Mar. 9, 2020, incorporated herein by reference in its entirety.

#The disclosure relates to a steering control device.

#For example, Japanese Unexamined Patent Application Publication No. 2019-131072 (JP 2019-131072 A) discloses an example of a so-called steer-by-wire steering device which is used for a vehicle and which includes a steering wheel that can be displaced without transmitting power to turning wheels.

#Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein:

#FIG. 1 is a diagram illustrating a steering device according to a first embodiment;

#FIG. 2 is a block diagram illustrating processes which are performed by a steering control device according to the first embodiment;

#Hereinafter, a first embodiment in which a steering control device is applied to a steer-by-wire steering device will be described with reference to the accompanying drawings.

#As illustrated in FIG. 1, a steering device 10 includes a steering mechanism 20, a turning actuator 50 that turns turning wheels 42, and the turning wheels 42. The steering mechanism 20 includes a steering wheel 22, a drag force actuator 30 that applies a drag force which is a force against a driver's operation of the steering wheel 22, a rack and pinion mechanism 27, and a clutch 24 that is interposed between an input shaft 32 rotating integrally with the steering wheel 22 and the rack and pinion mechanism 27.

#The drag force actuator 30 includes an input shaft 32, a reduction gear 34, a steering-side electric motor 36, and an inverter 38, and applies power of the steering-side electric motor 36 to the input shaft 32 via the reduction gear 34. In this embodiment, a three-phase surface permanent magnet synchronous motor (SPMSM) is exemplified as the steering-side electric motor 36. The rack and pinion mechanism 27 includes a pinion shaft 26 which is mechanically connected to the input shaft 32 via the clutch 24 and a rack shaft 28, and converts a rotational force of the pinion shaft 26 to a displacement in an axial direction of the rack shaft 28. The clutch 24 transmits power of the input shaft 32 to the pinion shaft 26 in an engaged state, and cuts off transmission of power between the input shaft 32 and the pinion shaft 26 in a disengaged state. In the engaged state of the clutch 24, a rotational force of the steering wheel 22 is converted to a displacement in the axial direction of the rack shaft 28, and this displacement in the axial direction is transmitted to the turning wheels 42 via tie rods 40 connected to both ends of the rack shaft 28, whereby a turning angle of the turning wheels 42 is changed.