Controller for vehicle continuously variable transmission

A controller for a vehicle continuously variable transmission, the vehicle continuously variable transmission including a primary pulley, which receives drive force from an internal combustion engine, a secondary pulley, which is coupled to a wheel, a belt, which runs around the pulleys to transmit the drive force from the primary pulley to the secondary pulley, and a rotation speed sensor, which detects a rotation speed of each of the pulleys, comprising:

• a controller that executes transmission control to vary a gear ratio by varying a transmission control oil pressure, which is an oil pressure of a first oil pressure chamber arranged in the primary pulley, and a narrowing control oil pressure, which is an oil pressure of a second oil pressure chamber arranged in the secondary pulley, while calculating an actual gear ratio based on the rotation speed of each pulley and executing feedback control so that the actual gear ratio conforms to a target gear ratio, wherein
• when the target gear ratio is set as a maximum gear ratio and a vehicle speed is decreased to less than a first reference vehicle speed, the controller suspends varying of the gear ratio by the transmission control and starts a gear ratio hold control that releases operational oil from the first oil pressure chamber and holds the gear ratio at the maximum gear ratio, and
• the controller ends the gear ratio hold control and delivers operational oil to the first oil pressure chamber when the vehicle speed increases to a second reference vehicle speed or greater, which is lower than the first reference vehicle speed, and restarts the varying of the gear ratio by the transmission control when the vehicle speed subsequently increases to the first reference speed or greater.