Flow control valve for antilock brake control device

Abstract

A flow control valve for use in an antilock control device includes a housing having inlet and outlet ports communicating with a pressure source and a wheel brake, respectively, and a spool slidably mounted in the housing and formed with a channel including an orifice. When the spool is in a first position, a large-flow passage is formed between the inlet and outlet ports. When in another position, a restricted-flow passage is formed between the inlet and outlet ports through the orifice while the large-flow passage is closed. A piston is mounted in the housing on top of the spool. Every time the brake is applied, the piston is adapted to move up and down, thus allowing the spool to slide in the same direction to the first position. Instead of the piston, a sleeve may be disposed between the inner periphery of the housing and the outer periphery of the spool so as to be slidable relative to both the housing and the spool. Every time the brake is applied, the sleeve is adapted to slide against the bias of a spring. In either arrangement, a relative movement takes place between the spool and the housing or the sleeve every time the brake is applied. This will prevent the spool from getting stuck between the first and second positions.