HYDRAULIC CONTROLLER FOR TRANSMISSION

PROBLEM TO BE SOLVED: To share a valve requiring large capacity in a hydraulic controller by combining the valve with a valve sufficient to have small capacity, and thereby reduce the size and weight of a hydraulic circuit. SOLUTION: This hydraulic controller for a transmission is provided with a flow rate control valve comprising an orifice 2 and a relief valve 3 and controlling the amount of drain which returns from an upstream side oil passage of the orifice 2 to a suction side oil passage (a) of an oil pump 1 in accordance with pressure difference before and after the orifice 2, between a discharge side oil passage (b) of the oil pump 1 and a hydraulic-activated circuit (c). A signal pressure selector valve 4 for controlling application and release of signal pressure with respect to the flow rate control valve is interposed in a signal pressure oil passage (e) applying hydraulic pressure in the orifice downstream side to the flow rate control valve. Due to this, the flow rate control valve can be operated also as an unloader valve with large capacity for releasing a pump drive load, and compared with the case where the unloader valve is actually mounted, reduction of the size and weight of the circuit is attained. COPYRIGHT: (C)2006,JPO&NCIPI