Hydraulic control valve apparatus and hydraulic drive system

摘要

PCT No. PCT/JP93/01558 Sec. 371 Date May 16, 1994 Sec. 102(e) Date May 16, 1994 PCT Filed Oct. 28, 1993 PCT Pub. No. WO94/10456 PCT Pub. Date May 11, 1994.A hydraulic control valve apparatus including a flow control valve having a pair of variable throttles, a feeder passage, a pair of load passages, directional control valve devices comprise a seat valve having a seat valve body movably disposed in a housing to form an auxiliary variable throttle in the feeder passage, and a control variable throttle (33) formed in the seat valve body for changing an opening area in accordance with an amount of movement of the seat valve body; (b) a pilot line (24, 29-31, 35-37) for communicating a portion (7C) of the feeder passage upstream of the auxiliary variable throttle with a downstream portion (7A, 7B) of the feeder passage through the control variable throttle to determine the amount of movement of the seat valve body in accordance with a flow rate of the hydraulic fluid passing through the pilot line; and (c) pilot flow control (400; 401; 403; 405; 406; 407; 408) having a pilot variable throttle (45) disposed in the pilot line and input (800; 52-59; 159, 54-59; 231A, 231B, 251, 252) for receiving a flow restricting signal whereby an opening area of the pilot variable throttle is changed in accordance with the received flow restricting signal to control a flow rate of the hydraulic fluid passing through the pilot line.