A control device for a continuously variable transmission, which sets a target input rotational speed, or a target value of an input rotational speed of the continuously variable transmission mounted on a vehicle, such that a speed ratio is changed in a stepped manner and which controls the continuously variable transmission such that the input rotational speed becomes equal to the target input rotational speed.

In a vehicle in which a continuously variable transmission and a gear mechanism are provided in parallel on a power transmission pathway between an input shaft and an output shaft, (i) an electronic control unit performs CVT shifting, in view of shift characteristics of C to C shifting in which the speed ratio is changed in stages, or (ii) then electronic control unit performs C to C shifting, in view of shift characteristics of CVT shifting in which the speed ratio is steplessly changed.

A powertrain system including a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining, employing a first controller, a first desired speed ratio in response to an output torque request. The first desired speed ratio is evaluated to determine if it is valid and achievable. A second controller is employed to determine a second desired speed ratio, and a final desired speed ratio is determined based upon the first and second desired speed ratios. The final desired speed ratio is evaluated, and the CVT is controlled based upon the final desired speed ratio.

A working machine having a belt-type continuously variable transmission in a working power transmission system includes a target working speed setting section for optionally setting a target working rotational speed of a working unit, a working unit speed sensor that detects an actual working rotational speed of the working unit, a speed reduction ratio regulation mechanism that regulates a minimum speed reduction ratio of a rotational speed of a driven pulley with respect to a drive pulley, and a control unit. The control unit controls a drive source rotational speed to bring the actual working rotational speed close to the target working rotational speed, obtains a minimum limit speed reduction ratio based upon a target minimum rotational speed of a drive source and the target working rotational speed, and controls the speed reduction ratio regulation mechanism to keep the minimum limit speed reduction ratio.

A belt-type continuously variable transmission capable of continuously changing a speed reduction ratio of a driven pulley to a drive pulley, has a speed reduction ratio regulation mechanism that regulates a minimum speed reduction ratio of the driven pulley to the drive pulley. The driven pulley includes a fixed sheave, a movable sheave displaceable in an axial direction with respect to the fixed sheave, and a coil spring that urges the movable sheave toward the fixed sheave. The speed reduction ratio regulation mechanism has a swing arm that adjusts an allowable range in which moving away in an axial direction of the movable sheave with respect to the fixed sheave is possible, and a regulation drive section that drives the swing distal end portion of the swing arm to swing continuously.