Other

Osamu Kanazawa

Mamoru Sawada

Hiroaki Niino

Michio Kobayashi

Kazuya Maki

Yoshiyasu Takasaki

Hiroyuki Oka

Hiroshi Ohsaki

Hidefumi Inoue

Masahiro Ikeda

Hiroyuki Yamaga

Hiroshi Osaki

Mitsuru Kakuda

The invention relates to a brake system including a brake booster. A pneumatic pressure operated brake booster VBB or a liquid pressure operated brake booster includes a valve mechanism which is urged by a force of depression applied to a brake pedal BP to switch a flow path to cause the brake booster to develop an output which depends on the magnitude of the force of depression. A solenoid SOL urges the valve mechanism in the same direction as or in the opposite direction from the force of depression. A controller ECU is responsive to a braking effort increase/decrease demand signal to increase or decrease the urging force which is applied by the solenoid to the valve mechanism, thus increasing or decreasing the output from the brake booster. An output from the brake booster can be freely controlled independently from the force of depression applied to the brake pedal in response to a braking effort increase/decrease demand. The arrangement is applicable to a wide variety of brake systems onboard a vehicle such as a regenerative brake unit, an engine brake or an exhaust gas brake unit or a brake assisting apparatus.

Brake system

In a brake booster of the present invention, by depression of a brake pedal an input shaft travels to the left, a pedal input converter generates thrust, and a valve element moves to the left. A valve passage is shut off from a valve passage and a valve passage is connected to a valve passage so as to develop output pressure Pr at an output port of a control valve because of the pressure of a pressure source. The output pressure Pr is supplied to a wheel cylinder thereby actuating the brake. At this point, since the displacement of the input shaft required for operating the control valve is defined only by the converter the input side is not affected by the brake rigidity of a circuit from the control valve to the wheel cylinder The output pressure Pr of the control valve acts on the valve element through a first reaction receiving portion and is regulated to pressure proportional to the thrust of the converter The second reaction force is transmitted to a driver through a second reaction receiving portion The control of the output can be conducted during the operation regardless of the input of the input side and the respective characteristics can be varied without being affected by the output side.

Brake booster

In a brake fluid pressure boosting device of the present invention, by operation, an input shaft is moves forward to rotate a lever to actuate a control valve so that the control valve produce working fluid pressure corresponding to the input. The working fluid pressure is introduced into the power chamber By this working fluid pressure, the primary piston is actuated to develop master cylinder pressure. On the other hand, the fluid pressure of the power chamber is introduced into the first annular groove of the valve spool By the difference between pressure receiving areas of the first annular groove the valve spool is subjected to rightward force. The position of the pivot of the lever is fixed and the valve spool is controlled in such a manner that the force applied to the valve spool and the spring force of the spool return spring balances with the input, thereby exhibiting the function as a stroke simulator. Because of this function as a stroke simulator, the stroke characteristic on the input side can be changed without affecting the output side.

Fluid pressure boosting device and brake system employing the same

Growing community of inventors

Higashimatsuyama, Japan

Osamu Kanazawa