HYDRAULIC CONTROL DEVICE OF BELT TYPE CONTINUOUSLY VARIABLE TRANSMISSION HAVING TORQUE CONVERTER

摘要

PROBLEM TO BE SOLVED: To surely prevent the belt slip by checking that the belt pressing hydraulic pressure is not lower than the hydraulic pressure when the switching signal is detected even when the switching is achieved in the control range due to the rise in the hydraulic pressure by confirming that the hydraulic pressure rises to the prescribed value. SOLUTION: When the timer value exceeds the switching delay control completion time, the belt pressing hydraulic pressure rises to the hydraulic pressure so as not to be lower than the hydraulic pressure when the signal changing to the lock-up on is detected even when the belt pressing hydraulic pressure is switched in the control range. As indicated by the arrow (d), the hydraulic pressure control characteristic of a linear solenoid valve is switched from the lock-up off to the lock-up on. The upper limit of the controlled pressure PLNR of the linear solenoid valve is regulated low. Because the controlled pressure PLNR is increased as indicated by the arrow (c) by the switching delay control, the controlled pressure PLNR is not lower than the hydraulic pressure P required at the present even when it is dropped as indicated by the arrow (d).