Mehrzweck-Ventilsteuerung für eine hydraulische Kupplung

摘要

A hydraulic coupling including a multi-plate clutch assembly operably connecting two relatively rotatable members and an actuator assembly for actuating the clutch assembly in response to speed differentiation between the two rotary members. The actuator assembly includes a hydraulic pump, a piston disposed in a piston chamber, and a fluid distribution system including a first flow path for supplying hydraulic fluid from a sump to the hydraulic pump and a second flow path for supplying hydraulic fluid from the hydraulic pump to the piston chamber. Hydraulic pressure in the piston chamber controls the magnitude of the clutch engagement force exerted by the piston on the clutch assembly. The fluid distribution system further includes a third flow path between the piston chamber and a clutch chamber. A control valve assembly is located in the third flow path and provides a flow control function for regulating the fluid pressure in the piston chamber and supplying fluid to the clutch chamber for cooling the clutch assembly. The control valve assembly also provides a pressure relief function for limiting the fluid pressure in the piston chamber to a predetermined maximum value, and a thermal unload feature for venting the piston chamber when the fluid temperature exceeds a predetermined maximum value.