Fluid pressure boosting device and brake system employing the same

Abstract

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.