ELECTROHYDRAULIC CONTROL DEVICE FOR A DRIVE TRAIN OF A VEHICLE

摘要

An Electrohydraulic Control Device for a Drive Train of a Vehicle A vehicle (12) such as an earthmoving wheel loader has an engine (14), a torque converter (20) having an impeller element (22), a reactor element (24) and a turbine element (28), and an input clutch (64) connected between the engine (14) and the impeller element (22). An electrohydraulic control device (76) is provided to controllably engage the input clutch (64) and that includes a microprocessor-based electronic control module (78), an actuator mechanism (120) having a control member (122) that is progressively movable between first, second and third positions to deliver a first electrical signal to the electronic control module (78), and a valve (170) for directing fluid to the input clutch (64) at a decreasing pressure level when the control member (122) is moved from the first to the second positions in response to another signal from the electronic control,module (78). The electronic control module (78) is programmed to maintain at least a minimal pressure level to the actuating piston (68) of the input clutch (64) when the control member (122) is between the second and third positions. Moreover, a service brake (150,152) is increasingly engaged by a service brake mechanism (128) in response to the control member (122) moving between the second and third positions. Other logic functions are included to control the input clutch (64) and a lockup clutch (66) connected between the engine (14) and the turbine element (28).