JP2009166763A5 - - Google Patents

Claims (7)

An electric power steering apparatus including a control unit that calculates a steering assist command value based on the steering torque and the vehicle speed, and controls a motor that applies a steering assist force to the steering mechanism based on the steering assist command value. In
A differential gear for adjusting a difference between the rotation speeds of the left and right wheels; and the control unit detects an abnormality of the electric power steering device, and an abnormality is detected by the abnormality detection unit. A steering assist switching determination unit that performs a first determination as to whether or not it is possible to continue steering assistance by the electric power steering device, and that the steering assistance cannot be continued by the first determination. An electric power steering apparatus, wherein, if determined, the differential gear performs alternative steering assistance based on a vehicle state. The differential gear is controlled by a differential gear control unit, and the differential gear control unit is controlled based on the left wheel speed detected by the left wheel speed sensor and the right wheel speed detected by the right wheel speed sensor. A rotational speed difference calculating unit that calculates a rotational speed difference between the wheel and the right wheel; a differential limiting torque calculating unit that calculates a differential limiting torque based on the steering torque and the rotational speed difference; and based on the vehicle state 2. The electric power steering apparatus according to claim 1 , wherein an alternative steering assist necessary amount calculation unit that calculates a required alternative steering assist torque, and the differential gear is controlled based on the differential limiting torque and the alternative steering assist torque. The control unit includes a steering assist condition setting unit, and when the abnormality is detected by the abnormality detection unit and the first determination determines that the steering assist can be continued, the steering assist condition setting is performed. The electric power steering apparatus according to claim 1 or 2 , wherein the unit restricts the steering assist under a certain condition according to the abnormality. The control unit includes a vehicle safety ensuring condition determination unit, and the steering assist switching determination unit determines whether the electric power steering device has returned to normal after a predetermined time after the alternative steering assist is performed. 2, and if it is determined by the second determination that the electric power steering device has returned to normal, the steering assist by the electric power steering device is returned, and the electric power steering device is determined by the second determination. When it is determined that the vehicle has not returned to normal, the vehicle safety ensuring condition determining unit determines the conditions for ensuring the safety of the vehicle. The electric power steering apparatus according to claim 3 , wherein the alternative steering assistance is continued when there is not. The steering assist switching determination unit performs a third determination as to whether or not the electric power steering apparatus has returned to normal after a predetermined time after limiting the steering assist under a certain condition, and the electric power is determined based on the third determination. When it is determined that the steering device has returned to normal, the restriction is released to return normal steering assistance, and when it is determined that the electric power steering device has not returned to normal, the vehicle safety ensuring condition The confirming unit confirms the conditions for ensuring the safety of the vehicle. When the condition is confirmed, the steering assist limited by the certain condition is stopped, and when the condition is not confirmed, the certain condition is satisfied. The electric power steering apparatus according to claim 4 , wherein the limited steering assist is continued. The electric power steering apparatus according to any one of claims 1 to 5 , wherein the vehicle state is the vehicle speed, the steering torque, and a steering angle signal. The electric power steering device is a steer-by-wire system in which a steering wheel and a steered wheel are mechanically disconnected, a control unit controls a steering actuator according to a steering angle of the handle, and the steered wheel is steered by the driving force. the electric power steering apparatus according to any one of claims 1 to 6, characterized in that an electric power steering device of the type.