CONTROL SYSTEM FOR TORQUE CONVERTER

摘要

A control system for a torque converter (1) comprising a lock-up clutch (30) provided in said torque converter (1) for connecting input and output members of the torque converter (1) directly. A shift valve (50) having first (54) and second spools (55) disposed in series in a sleeve for shifting an introduction of an engaging and releasing pressure acting on the lock-up clutch (30) in accordance with positions of the first (54) and second spools (55). The first spool (54) is subjected to a first hydraulic pressure at one end thereof. The second spool (55) is subjected to a second hydraulic pressure at one end thereof opposite to said one end of the first spool (54). The first (54) and second spools (55) are subjected to a third hydraulic pressure therebetween. The control system further comprises a first control device for controlling the first hydraulic pressure, an adjusting valve (60) for controlling the releasing pressure of the lock-up clutch means (30). The shift valve means (50) provide the first (54) and second spools (55) with a first, second and third positions corresponding to a converter condition, lock-up condition and slip condition respectively. The shift valve (50) is shifted between the second and third positions when the releasing pressure is relatively low so that the releasing pressure is continuously changed irrespective of the shifting action among the first, second and third positions on the shift valve (50). An abrupt change in the engaging force of the lock-up clutch (30) is prevented.