Hitachi, Ltd.

Yoshinari Kawahara

Atsushi Yokoyama

Satoru Kuragaki

Kenji Hiraku

Hiroyuki Saito

Mitsuhide Sasaki

Tohma Yamaguchi

Hirotaka Oikawa

Takaomi Nishigaito

Tadahiko Nogami

Kousaku Ohno

Provided is an electric brake capable of accurately estimating the brake pad temperature and securing a sufficient braking force and response. An electric brake has a disc rotor rotating with a wheel, an actuator for rectilinearly actuating a piston in the axial direction of the disc rotor by using an electric motor, a drive controller for controlling the drive of the actuator, a brake pad pressed by the piston to give a frictional resistance to the disc rotor in the direction of rotation, and a braking start position detector for detecting a braking start position of the piston where the disc rotor is brought into contact with the brake pad. The drive controller stores the braking start position detected by the braking start position detector as the maximum braking start position. When the braking start position shifts in the pressing force-increasing direction, the drive controller updates the value stored as the maximum braking-start position.

Electric brake

A motor-driven disk brake system is capable of preventing a pressing member from moving beyond a predetermined position at a time of stopping a motor. When a command for system termination is issued, motor current is reduced intermittently, which correspondingly reduces a motor displacement gradually such that a return force is spent gradually on a return displacement of a motor and a piston, thereby preventing a rotational speed of a rotor from increasing. A large accelerated backward movement of the motor and the piston beyond a predetermined position due to inertia is thereby prevented, because the return force does not act all at once during the return displacement of the motor and the piston. Accordingly, the piston is stopped near a standby position of non-braking state before system termination. As a result, a next activation of the motor-driven disk brake system can be conducted promptly.

Motor-driven disk brake system and control device for the motor-driven disk brake system

An electro-mechanical brake achieves a safe traveling and braking with a high accuracy device for detecting a piston position at which a brake pad and a disk rotor contact each other. A pad contact position detecting device in which an electric circuit is not formed to prevent an electric current from flowing therethrough when a pad pressing force is not generated and the electric circuit is formed to enable the electric current to flow therethrough when the pad pressing force is generated is applied to the electro-mechanical brake. A pad contact position can thereby be detected accurately.

Electro-mechanical brake

The invention provides an electro-mechanical brake system which can keep a stop state even if a malfunction is generated in a parking brake, and an electro-mechanical brake apparatus used for the electro-mechanical brake system. An electro-mechanical brake actuator presses a brake pad to a disc rotor so as to independently brake a braking force of each of wheels. A parking brake is constituted by a pawl portion attached to a motor of a motor driving the electro-mechanical actuator and a latch. A main controller detects a failure of the parking brake on the basis of a motor displacement at a time of reducing a motor current, and increases the pressing force in the remaining normal parking brake in the case that the parking brake failure in one wheel or more is detected.

Electro-mechanical brake system and electro-mechanical brake apparatus used therefor

A brake control apparatus for a vehicle having brake devices for generating pad-pressing forces at respective wheels includes brake control units for individually controlling the pad-pressing forces at the respective wheels; a storing unit for storing drive data required for controlling the pad-pressing force at each wheel; a vehicle-driving-state detector for detecting a driving state of the vehicle; and a vehicle controller for controlling a vehicle driving state using the brake control unit for each wheel. Memory data representing the relationship between a motor position and the pad-pressing force is updated using the state of brake actuators obtained when the driving state of the vehicle is stabilized by operating the brake devices during braking.

Brake control apparatus for vehicle

An electrically operated brake device in which braking force differences between electrically operated brakes are reduced to prevent unstable vehicle traveling during braking. Motorsof electrically operated brakes are returned to standard positions during the stop of a vehicle and the motorof each of the brakes is driven for a predetermined amount, pressing a brake padagainst a disc rotorto produce a braking force. An electric current value of each motorin the above operation is measured and differences between the values are calculated. Electric current of each motor is increased or decreased so that there is no current difference between the motors. Based on a drive amount of each motor in this operation, standard positions of the motors are determined and updated. Repeating the above operations reduces braking force differences between the brakes.

Growing community of inventors

Fukuoka, Japan

Yoshinari Kawahara