Brake fluid pressure control apparatus for antiskid control and traction control

A brake fluid pressure control apparatus for controlling fluid pressure in an antiskid braking system of a vehicle having a master cylinder operatively connected to a pedal, and having a wheel cylinder associated with each wheel of said vehicle, wherein the fluid pressure is reduced or increased in accordance with a condition of skidding of each wheel, said apparatus comprising a flow value and a flow switching device:

• wherein the flow valve comprises:
• (a) a casing having a master cylinder communication port communicating with an output fluid passage of said master cylinder;
• a wheel cylinder communication port communicating with said wheel cylinder;
• a pump communication port communicating with a discharge side of a pumping device for intaking and discharging brake fluid;
• (b) a spool slidably disposed in said casing, said spool being in a stationary position when antiskid control is not operating by being pressed by a spool spring so as to communicate said master cylinder communication port with said wheel cylinder communication port;
• and
• (c) a fluid flow control device which closes said pump communication port when the spool is in said stationary position, and at least during a repressurization phase of antiskid control operation, said spool moves against the biasing force of said spool spring to an operating position because of a pressure differential generated between the end sections of said spool, and communicates said pump communication port with said wheel cylinder communication port;
• and
• said flow switching device is disposed between said output fluid passage of said master cylinder and said master cylinder communication port for switching between a first state and a second state, such that in said first state, said master cylinder communication port is communicated with said output fluid passage of said master cylinder while the communication between said pump communication port and said master cylinder communication port is shut-off, and in said second state, the communication between said master cylinder communication port and said output fluid passage of said master cylinder is shut-off while said pump communication port is communicated with said master cylinder communication port.