Patent ID: 7998006
Filing Date: 2011-08-16
Classification: F16H,Y10T

Abstract:
1. A speed ratio control device for a belt continuously variable transmission in which a belt is wrapped around a primary pulley connected to an input side of a vehicle drive system and a secondary pulley connected to an output side, a groove width of the primary pulley and the secondary pulley is varied by controlling an oil pressure supplied by a hydraulic pump, a speed ratio is varied in accordance with the groove width, and the transmission operates in a fixed speed ratio mode in which a target speed ratio is held at a fixed value, the device comprising a controller which: calculates the target speed ratio on a basis of a driving condition of a vehicle; feedback-controls the speed ratio on a basis of a difference between an actual speed ratio and the target speed ratio; and corrects pressure supplied to the primary pulley to a lower pressure by addition of a predetermined correction amount to the target speed ratio when an input torque into the primary pulley decreases rapidly while traveling in the fixed speed ratio mode in which the target speed ratio is held at the fixed value, and to a higher pressure by subtraction of the predetermined correction amount from the target speed ratio when the input torque into the primary pulley increases rapidly while traveling in the fixed speed ratio mode.