Control of toroidal continuously variable transmission

A control device of a toroidal continuously variable transmission for a vehicle, the vehicle comprising an accelerator pedal, and the toroidal continuously variable transmission comprising an input disk, an output disk, a power roller which transmits torque between the input disk and the output disk, a trunnion which supports the power roller free to rotate, the trunnion comprising a trunnion shaft, the power roller varying a gyration angle (φ) according to a displacement (y) of the trunnion in the direction of the trunnion shaft to vary a speed ratio of the input disk and output disk, and an oil pressure actuator which drives the trunnion in the direction of the trunnion shaft, the device comprising:

• means for supplying oil pressure to the oil pressure actuator;
• means for connecting the trunnion and the control valve to feed back the displacement of the trunnion to the control valve;
• means for controlling the supplying means according to a command value (u);
• means for detecting a rotation speed (ωco) of the output disk;
• means for detecting a depression amount (APS) of the accelerator pedal;
• means for detecting the gyration angle (φ) of the power roller;
• means for detecting the displacement (y) of the trunnion in the direction of the trunnion shaft;
• means for calculating a target control variable (z*) which is a target value of a control variable (z) being an object of control, based on the accelerator pedal depression amount (APS) and the output disk rotation speed (ωco);
• means for calculating a time-variant coefficient (f) representing the relation between the displacement (y) of the trunnion in the direction of the trunnion shaft and a variation rate ({dot over (φ)}) of the gyration angle (φ) of the power roller;
• means for calculating a first time differential ({dot over (f)}) which is a time differential of the time-variant coefficient (f);
• and
• means for determining the command value (u) by applying a control gain based on the first time differential ({dot over (f)}).

A control method of a toroidal continuously variable transmission for a vehicle, the vehicle comprising an accelerator pedal, and the toroidal continuously variable transmission comprising an input disk, an output disk, a power roller which transmits torque between the input disk and the output disk, a trunnion which supports the power roller free to rotate, the trunnion comprising a trunnion shaft, the power roller varying a gyration angle (φ) according to a displacement (y) of the trunnion in the direction of the trunnion shaft to vary a speed ratio of the input disk and output disk, an oil pressure actuator which drives the trunnion in the direction of the trunnion shaft, a control valve which supplies oil pressure to the oil pressure actuator, a mechanical feedback mechanism connecting the trunnion and the control valve to feed back the displacement of the trunnion to the control valve, and a valve actuator which controls the control valve according to a command value (u), the method comprising:

• detecting a rotation speed (ωco) of the output disk;
• detecting a depression amount (APS) of the accelerator pedal;
• detecting the gyration angle (φ) of the power roller;
• detecting the displacement (y) of the trunnion in the direction of the trunnion shaft;
• calculating a target control variable (z*) which is a target value of a control variable (z) being an object of control, based on the accelerator pedal depression amount (APS) and the output disk rotation speed (ωco);
• calculating a time-variant coefficient (f) representing the relation between the displacement (y) of the trunnion in the direction of the trunnion shaft and a variation rate ({dot over (φ)}) of the gyration angle (φ) of the power roller;
• calculating a first time differential ({dot over (f)}) which is a time differential of the time-variant coefficient (f);
• and
• determining the command value (u) by applying a control gain based on the first time differential ({dot over (f)}).