Lock-up control system for controlling lock-up clutch employed in a torque converter

摘要

A control system for controlling a lock-up clutch of a torque converter employed in an automatic transmission of a vehicle, the lock-up clutch being controllable by a pressure differential between apply and release pressures comprises a detector for detecting a demand of change (decrease/increase) in the pressure differential, a pressure-differential setting circuit for setting a target pressure differential in response to the demand of change in the pressure differential, and a pressure-differential filter having a desired dynamic characteristic and being responsive to the target pressure differential for outputting a filtered pressure-differential command value via a filtering process based on the desired dynamic characteristic. A pressure-differential regulation circuit is connected to the pressure-differential filter for receiving the filtered pressure-differential command value as an input information data to generate an output indicative of a duty ratio to be output to a lock-up solenoid valve and for regulating the pressure differential in accordance with the duty ratio.