Toyota Jidosha Kabushiki Kaisha

Masaki Fujimoto

Masaharu Yamashita

Eiji Kasai

Kenichiro Aoki

Keitaro Niki

Akihiro Ohtomo

Tsutomu Onagi

Takatoshi Saito

Megumu Nishikohri

Shigeki Tashiro

A steering angle estimation section calculates a front-wheel-side estimative steering angle and a rear-wheel-side estimative steering angle through use of wheel speeds of respective wheels, and averages these steering angles to thereby obtain an accurate estimative steering angle. It also calculates an estimative steering angle difference between the steering angles. An axial force estimation section calculates a base axial force through use of the estimative steering angle and a vehicle speed, and calculates a correction axial force which applies an axial force difference (hysteresis) to the base axial force in accordance with a turning or returning operation by a driver. The axial force estimation section adds the base axial force and the correction axial force together to thereby calculate an accurate estimative axial force. An assist computation section compares a target steering torque, which changes with the vehicle speed, and the accurate estimative axial force, and subtracts the target steering torque from the estimative axial force, to thereby calculate an assist torque.

Electric power steering apparatus for vehicle

In a center-takeoff-type steering apparatus for a vehicle, radiant heat from a heat source such as an engine is shut off reliably. The bracket is fixed to a central portion of a rack bar for unitary movement, the rack bar moving in the lateral direction in accordance with a steering operation of a steering wheel. Ball joint mechanisms are assembled to the bracket. The ball joint mechanisms rotatably support the inboard ends of the tie rods, swing tie rods in accordance with the movement of the rack bar to thereby steer the left and right front wheels. The heat insulator is integrally formed to have an upper plate portion and a lower plate portion facing each other, and fixed to the bracket so as to cover the ball joint mechanisms.

Vehicular steering device

An electric power steering device for a vehicle includes an estimation mechanism estimating if there is a possibility that a backward electric current flows in a booster circuit toward a vehicle battery device, and a boosting controller stopping the boosting operation of the booster circuit to prevent a backward electric current from flowing in the booster circuit when it is estimated that there is a possibility that a backward electric current flows by the estimation mechanism. The estimation mechanism estimates that there is a possibility that a backward electric current flows in the booster circuit when the steering condition of a steering wheel is a returning condition or a steering-held condition. Otherwise, the estimation mechanism estimates if a backward electric current flows on the basis of input and output voltages of the booster circuit and information on the switching of a first boosting switching element. Thereby, overheat of the booster circuit can be prevented.

Electric power steering device

An Assist Control Unitdetects a power generation state of an electric motor where the direction for generating torque of motor current im does not match the rotational direction of steering speed &#x3c9;x (S), and calculates an Amount E Corresponding to Power Generation Energy during a period when the power generation state is detected continuously (S). When the Amount E Corresponding to Power Generation Energy exceeds a Criterion Value E(S: Yes), the state is judged as a reverse input state that a large reverse input is acting on a steering mechanism from a tire. Consequently, a small reverse input state not affecting the steering mechanism is excluded, and a large reverse input state having a risk of affecting the steering mechanism can be detected precisely.

A power steering system, which is disposed in the forward part of a vehicle, allows an electric motor to boost the steering torque applied by a driver, and transmits the steering torque to wheels via a steering transmission mechanism. The power steering system includes an impact detection device that detects the impact of an object on a rack housing that houses a rack bar constituting the steering transmission mechanism to detect the impact on the power steering system more accurately.

Growing community of inventors

Toyota, Japan

Masaki Fujimoto