Jidosha Kiki Co., Ltd.

Bosch Braking Systems Co. Ltd.

Robert Boschgmbh

Toshiaki Fukushima

Yuzi Wachi

In a brake system, a controller closes solenoid shut-off valves to shut off a communication between a master cylinder and wheel cylinders by pressing a brake pedal, and at the same time, drives a pump and controls the operation of brake fluid pressure control means to supply brake fluid through the pump to the wheel cylinders, thereby performing braking action. Idle travels of the wheel cylinders can be cancelled by the brake fluid from the pump, and a very short pedal stroke can be obtained. Since the brake characteristics are set by considering three factors, i.e. pedal characteristics, travel of a brake pedal, and deceleration (brake fluid pressure) of a vehicle, the brake system has a very short stroke of the brake pedal as compared to a conventional one and has optimal brake characteristics.

Brake system

In a fluid pressure booster, an input rod,and a valve member,are stroked forward during the operation so as to cause a control valve to be switched over. The atmosphere is introduced into a working pressure chamber,via the control valve,and a power piston,then operates to make a negative pressure booster,produces an output from a output rod,. As the atmosphere in the working pressure chamber,acts backward on a control piston,at this time, the valve member,will not be stroke further. However, the output rod,is continuously stroked forward and kept producing the output. Due to the stop of stroke of the valve member,, the stroke of the input rod,is suppressed and set at an extremely short stroke. When the negative pressure falls, the negative pressure booster,produces an output from the output rod,since the input rod,, the valve member,and the output rod,integrally give a stroke forward.

Fluid pressure booster and brake system using the same

An electrically controlled braking system allows a pedal stroke produced by an operation of a brake pedal to be detected by a stroke sensor and to be input to a controller, which in turn controls a brake pressure generated by a brake pressure generator in accordance with the magnitude of the pedal stroke. A pedal reaction unit is added to the brake pressure generator. The pedal reaction unit comprises an air cylinder connected to the brake pedal, the stroke sensor which detects the pedal stroke, and a pair of solenoid operated open/close valves for feeding the air pressure from an air tank to, or displacing the air pressure from, the air cylinder. The controller causes the air to be fed to or displaced from the air cylinder in accordance with the magnitude of the pedal stroke detected by the stroke sensor, thus producing a pedal reaction having a controlled magnitude.

Growing community of inventors

Saitama, Japan

Toshiaki Fukushima