CONTROL DEVICE FOR A DIRECT-COUPLING HYDRAULIC CLUTCH IN A HYDRAULIC TORQUE CONVERTER

摘要

A control device for controlling the operation of a direct- coupling hydraulic clutch of a hydraulic torque converter for use in an automotive vehicle, wherein the hydraulic torque converter is coupled to a transmission of the automotive vehicle selectable at a plurality of transmission gear ratios. A first fluid line is connected to the direct- coupling hydraulic clutch for supplying same with operating fluid pressure generated by an operating fluid pressure source. A selector valve is arranged across the first fluid line and shiftable to a first or a second position thereof in response to a transmission gear ratio established by the transmission, and is adapted to open the first fluid line when it assumes the first or second position, and to close the first fluid line when it assumes a third position between the first and second positions. A second fluid line branches off from the first fluid line at a location between the selector valve and the direct-coupling hydraulic clutch and communicates with a zone under lower pressure, and across which the selector valve is arranged. The selector valve has a valve operable to close the second fluid line when the first or second position is assumed, and to open the second fluid line to thereby escape operating oil pressure to the zone under lower pressure when the third position is assumed. Preferably, at least one restriction is arranged in the first fluid line at a location between the junction of the first and second fluid lines and the operating fluid pressure source.