CLUTCH CONTROLLER OF HYDRAULIC TRANSMISSION FOR VEHICLES

摘要

PURPOSE:To prevent an engine speed from going up over the extent of necessity, by constituting a clutch valve so as to keep the opening of a short circuit passage to a constant value within a fixed range in a valve opening direction from an opening position corresponding to an idling state of an engine. CONSTITUTION:A hydraulic stepless transmission T consists of a constant discharge hydraulic pump 2 having an input shaft 1 to be driven by an engine E and a variable displacement hydraulic motor 4 having an output shaft 3 driving wheels W. The pump 2 and the motor 4 are connected with each other by a hydraulic closed circuit 5, while a short circuit passage 6 is connected to this circuit 5 and there is provided with a clutch valve CV which is driven by a servomotor 15 to which a first control unit 16 showing controlling force proportionate to throttle opening for driving this valve CV in its opening direction and a second control unit 17 showing the controlling force proportionate to an engine speed for driving the valve CV in its closing direction both are connected.