Koyo Seiko Company, Ltd.

Mitsubishi Denki Kabushiki Kaisha

Koyo Seikoco., Ltd.

Hidetoshi Tabuse

Hirofumi Matsuoka

Toshihiko Daido

Mitsuhiko Nishimoto

Disclosed is an electric power steering apparatus, in which a gate circuit is provided that allows the actuation of a motor and a clutch only when a signal indicating normal operation is obtained from both of two controllers of dual configuration and that immediately disables steering assisting action when either one or both of the two controllers have gone out of control, and in which a power supply for supplying power to the controllers is connected in common to the two controllers, to prevent a latch-up of either controller.

Electric power steering apparatus

A power steering apparatus having a torque sensor for detecting steering force, an actuator for assisting the steering force according to the torque detected by the torque sensor, two vehicle speed sensors for detecting vehicle speed, and a microcomputer for controlling the actuator according to the detection results by the vehicle speed sensors. When the difference between the vehicle speed values detected by the two vehicle speed sensors becomes greater than a predetermined value, the greater vehicle speed value of the two is integrated to obtain a control vehicle speed value for control of the actuator. When the vehicle speed value difference is greater than the predetermined value and remains in that state for more than a predetermined duration of time, either a predetermined vehicle speed value is set as the control vehicle speed value or the operation of the actuator is disabled.

Power steering apparatus

In an electric power steering apparatus which assists a steering power by an electric motor, the difference between currents flowing into and flowing out from the electric motor is obtained, and an abnormality of the electric motor due to a ground fault is detected on the basis of this difference. When a state in which this difference is greater than a given value has continued for a predetermined period of time, the abnormality of the electric motor is detected. Upon the detection of the abnormality of the electric motor, a relay contact of a fail-safe relay circuit is made off so that the supply of electric power from a main power supply to the electric motor is cut off, thereby inhibiting the electric motor from assisting the steering power.

Electric power steering apparatus having overload protection

An electric power steering apparatus has a main CPU for performing a drive control for steering assistance over a steering assistance motor based on the detected steering torque and detected vehicle speed and a sub CPU for detecting abnormality in the main CPU by monitoring inputs and outputs to and from the main CPU, wherein the sub CPU is destined to detect abnormality in the main CPU only when the drive control for steering assistance is performed by the main CPU.

The electric power steering apparatus of the invention is provided with a rotary detector for detecting a rotational position of a motor, a torque sensor for detecting a steering torque, and when the steering torque is within a dead zone, by increasing flow current to a motor for assisting steering force correspondingly to increase of a steering angle decided on the basis of the rotational position of the motor, the steering assisting force corresponding to the steering angle can be gained at the time of returning the steering wheel steered by mostly using by the steering torque being in the dead zone, and the proper steering assisting force can also be gained by making flow quantity corresponding to the steering angle to be minimum within a predetermined speed range and by increasing it at lower or higher speed than the predetermined speed range when the steering wheel is returned during a time of running at a low speed (such as a time of slowing down).

Motor-driven power steering apparatus

An electric power steering apparatus of the invention is provided with a rotary detector for detecting a rotational position of a motor, a vehicle speed sensor for detecting a vehicle speed, a torque sensor for detecting a steering torque, a calculating means for calculating angular velocity of aforesaid motor on the basis of aforesaid rotational position, and a target angular velocity setting means, wherein flow quantity of electric current to a motor for assisting steering force is made larger, when the steering torque is within a dead zone, correspondingly to the increase of the deviation on the basis of the deviation between the target angular velocity and the calculated angular velocity, thereby stabilized steering feeling in the vicinity of the steering angle middle point at the time of returning the steering wheel steered by mostly using the steering torque being in the dead zone. And this power steering apparatus is capable of fully following up the rotation of the steering wheel as well as preventing the extreme returning of the steering wheel at the time of returning control, by subtracting subtractor current which is made small when both the steering torque and angular velocity are large, and made large when the steering torque is small and the angular velocity is large, from the driving current.

Power steering apparatus and rotary detector used therefor

A motor-driven power steering apparatus comprising a steering assisting motor, a torque sensor detecting steering torque, a vehicle speed sensor, and a steering angular velocity detecting unit detecting steering angular velocity of steering mechanism. The power steering apparatus sets the value of current to be delivered to the steering assisting motor in correspondence with the detected steering torque and vehicle speed. The power steering apparatus sets the current value to be 0 when the steering torque remains in the dead zone in which the steering torque value is less than the first predetermined value. If the steering torque is more than the first predetermined value and less than the second predetermined value, the current value is set to increase as the steering torque value increases. If the steering torque is in excess of the second predetermined value, the growth rate of the current value against the steering torque is set to diminish as the vehicle speed rises. Further, the apparatus sets the subtraction current of which value increases as the detected steering angular velocity and the vehicle speed increases, and then subtracts the subtraction current from the set current value, transmitting the substracted result to the motor. Since the value of the subtraction current grows when the vehicle runs fast and a small value of current is set, only a small amount of current flows through the motor.

An electric power steering system comprising a power unit consisting essentially of drive circuits for an electric motor and the like, and a control unit separate from the power unit and consisting essentially of a control circuit for controlling the drive circuits. The control unit is connected to each of the drive circuits of the power unit by a transmission line for the control unit to transmit therethrough 'ON' or 'OFF' representing logical control signals to the drive circuit to thereby control the drive circuit. The power steering system has first signal conversion means provided in the control unit for converting an 'ON' representing logical control signal to a pulse signal, and second signal conversion means provided in the power unit and connected to the first signal conversion means by a transmission line for producing an 'ON' logical control signal when the input signal given is the pulse signal or for producing an 'OFF' logical control signal when the input signal is not the pulse signal.

Electric power steering system

The motor-driven power steering control apparatus of the invention detects overload of a motor according to the calculation of coil resistance and temperature detection based thereon. The coil resistance is calculated according to terminal voltage or effective voltage based on duty ratio, and counter-electromotive force, and the driving current. Thereby overload of the motor can be detected without delay.

Motor-driven power steering control apparatus

A steering angle middle point detecting apparatus of the invention is provided with a vehicle speed sensor for detecting vehicle speed, a torque sensor for detecting at regular intervals steering torque to be added to a steering wheel, a steering position detecting means for detecting a steering position of a steering mechanism, a means for comparing a steering torque set value previously set corresponding to the vehicle speed with the steering torque detected by the torque sensor, and a steering angle middle point calculating means for calculating a middle point of a steering angle by using the steering position of the steering mechanism detected by the steering position detecting means when the steering torque is smaller than the steering torque set value, which judges that the vehicle goes straight when the detected steering torque is smaller than the steering torque set value corresponding to the vehicle speed, and judges the steering position at that time to be the middle point of the steering angle. Further, another steering angle middle point detecting apparatus is added: a judgment of an angle velocity of the steering angle, that is, a rotational speed of the steering wheel or variation of the steering torque; determines that the vehicle goes straight when it is at the specified value or less, and judges the steering position at that time to be the middle point of the steering angle.

Growing community of inventors

Osaka, Japan

Hidetoshi Tabuse