Fluid pressure controlling device for vehicle braking system

摘要

An improved fluid pressure controlling device for a vehicle braking system has a valve housing provided with an input chamber communicating with an output port of a master cylinder and an output chamber communicating with a rear wheel brake. A resilient valve seat separating the input and output chambers from each other is disposed in the input chamber. The resilient valve seat is provided with a valve port through which the input and output chambers are communicate with each other. A valve member is accommodated in the output chamber for opening and closing the valve port. The valve member is resiliently biased by a spring in a direction to move the pressure-receiving piston away from the resilient valve seat. The valve seat has an inner peripheral portion with a conical valve seat surface opposing the valve member and an annular thin-walled portion surrounding the inner peripheral portion. The annular thin-walled portion is seatingly engageable with the valve member and deformable to improve responsiveness of the valve member to pressure differential between the input and output chambers, whereby excellent sealing between the input and output chambers is provided without any accompanying substantial braking hysteresis during the brake-releasing operation.