Hitachi Automotive Systems, Ltd.

Daisuke Kojima

Kentaro Ueno

Tohma Yamaguchi

Yusuke Nozawa

Yukihiko Yamada

An electric motor is controlled based on an operation of a brake pedal to move a primary piston forward through a ball screw mechanism, thereby generating a hydraulic pressure in a master cylinder. At this time, a reaction force from the hydraulic pressure in the master cylinder is fed back to the brake pedal through an input piston. Automatic brake control, which generates the hydraulic pressure by driving the electric motor regardless of whether there is the operation of the brake pedal, is carried out. During the automatic brake control, an actual relative position is compared with a determination threshold value set based on the relative position between the primary piston and the input piston which is generated by a movement of the primary piston, and it is determined that the brake pedal is operated in a case where the relative position is smaller than the determination threshold value.

Electric booster

A brake control system displaces a primary piston by controlling an operation of the electric motor by a master pressure control unit according to the operation amount (Xop) of the brake pedal, thereby generating a hydraulic pressure in the master cylinder to supply it to wheel cylinders (Ba to Bd). The master pressure control unit sets a target relative displacement (&#x394;XT) between an input piston and the primary piston and a target hydraulic pressure (PT) in the master cylinder, and appropriately switch which is used to control a brake force. During regenerative cooperation, the master pressure control unit selects the control with use of the target hydraulic pressure, which enables easy execution of a hydraulic pressure control including a subtraction of the hydraulic pressure corresponding to a brake effect from the regenerative cooperation.

Growing community of inventors

Minami-Alps, Japan

Daisuke Kojima