Flow control valve apparatus

Abstract

A flow control valve apparatus includes a housing including a main fluid passage having an inlet port and an outlet port; a main valve disposed between the inlet port and the outlet port for allowing or shutting off communication between the inlet port and the outlet port; a backpressure chamber formed between an inner wall of the housing and a rear portion of a valve member of the main valve, the backpressure chamber communicating with the inlet port through an orifice; an auxiliary passage for placing the backpressure chamber in communication with the outlet port; and a pivot valve for actuating the main valve by controlling the opening and closing of the auxiliary passage and varying the fluid pressure in the backpressure chamber. A differential pressure generating means is disposed in the main fluid passage for generating differential pressures that correspond to the flow rate in the main fluid passage. The differential generating means includes a displacement member disposed for movement in the direction in which a fluid flows in the main fluid passage and spring means for urging the displacement member in the direction opposite to the direction in which the fluid flows, and the displacement member cooperates with a wall surface of the main fluid passage to define a fluid passage having an opening area which increases in accordance with an increase in the stroke of travel of the displacement member.