Patent ID: 8105191
Filing Date: 2012-01-31
Classification: F16H,Y10T

Abstract:
1. A control apparatus for a belt type continuously variable transmission that is provided on a power transmission path between a drive power source and drive wheels in a vehicle and has a primary pulley, a secondary pulley, a belt that is wound around the primary pulley and the secondary pulley, a primary-pulley-side hydraulic cylinder that is used to change a width of a groove of the primary pulley, and a secondary-pulley-side hydraulic cylinder that is used to change a width of a groove of the secondary pulley, the control apparatus being adapted to change a speed ratio of the continuously variable transmission by operating the primary-pulley-side hydraulic cylinder so as to eliminate a deviation between a target speed ratio related value and an actual speed ratio related value and to control a belt clamping force by operating the secondary-pulley-side hydraulic cylinder so as to prevent slipping between the belt and the primary pulley and slipping between the belt and the secondary pulley, the control apparatus comprising: a steady balance pressure calculating portion that calculates a steady balance pressure for maintaining the speed ratio constant; a required shift pressure calculating portion that calculates a required shift pressure for changing the groove width of the primary pulley to change the speed ratio; a primary hydraulic pressure calculating portion that, when the continuously variable transmission is to be shifted up, calculates a hydraulic pressure of the primary-pulley-side hydraulic cylinder based on the steady balance pressure and a higher of the required shift pressure calculated based on a rate of change in the target speed ratio related value and the required shift pressure calculated based on a rate of change in the actual speed ratio related value; and a base pressure setting portion that obtains a base pressure based on the hydraulic pressure of the primary-pulley-side hydraulic cylinder calculated by the primary hydraulic pressure calculating portion and the hydraulic pressure of the secondary-pulley-side hydraulic cylinder, and subsequently sets the hydraulic pressures of the primary-pulley-side hydraulic cylinder and the secondary-pulley-side hydraulic cylinder to the base pressure.