Controller for Vehicle Power Transmission System

A controller for a vehicle power transmission system, the vehicle power transmission system including:

• a gear mechanism, a belt-type continuously variable transmission and a switching mechanism, the gear mechanism and the belt-type continuously variable transmission being provided in parallel with each other in power transmission paths between an input shaft and an output shaft, the belt-type continuously variable transmission including an input-side sheave and an output-side sheave, the switching mechanism being configured to selectively establish any one of a first transmission path and a second transmission path, the first transmission path being a path through which torque input from the input shaft is transmitted to the output shaft via the belt-type continuously variable transmission, the second transmission path being a path through which torque input from the input shaft is transmitted to the output shaft via the gear mechanism, the controller comprising:
• an actual speed ratio calculation unit configured to calculate an actual speed ratio in the belt-type continuously variable transmission;
• a target speed ratio setting unit configured to set a target speed ratio of the belt-type continuously variable transmission;
• a hydraulic pressure output device configured to control hydraulic pressure that is output to the input-side sheave based on the target speed ratio;
• and
• a normal state return determination unit configured to, when there is a failure in the hydraulic pressure output device, establish a state where torque is transmitted through the second transmission path, and determine whether the hydraulic pressure output device has returned to a normal state by comparing the target speed ratio and actual speed ratio of the belt-type continuously variable transmission with each other in the state where torque is transmitted through the second transmission path.