Continuously variable transmission and shift control method

A shift control method for a continuously variable transmission which includes a variator which changes a speed ratio continuously and a stepped sub-transmission mechanism provided in series with the variator and capable of switching a speed ratio depending on engagement and release of a plurality of friction elements, and is installed in a vehicle to shift and output the output rotation of a driving source;

• comprising:
• setting a final through speed ratio as a target speed ratio based on a driving condition of the vehicle;
• causing a through speed ratio, which is an overall speed ratio of the variator and the sub-transmission mechanism, to follow the final through speed ratio in a specified response by changing at least one of the speed ratio of the variator or a gear position of the sub-transmission mechanism;
• causing the through speed ratio to follow the final through speed ratio by changing only the speed ratio of the variator if a shift instruction is given from the driver a plurality of times in a row when a manual mode is set in which a plurality of gear positions are set beforehand and a speed ratio corresponding to any one of the plurality of gear positions is set as the final through speed ratio based on a shift instruction from the driver;
• and
• advancing the start of a change in the speed ratio of the sub-transmission mechanism or accelerating the progression of the change of the speed ratio as compared with the case where the manual mode is not selected when the speed ratio of the variator is maximized or minimized and the through speed ratio cannot follow the final through speed ratio.

A continuously variable transmission installed in a vehicle to shift a rotation speed of an engine, comprising:

• a variator which changes a speed ratio continuously;
• a stepped sub-transmission mechanism provided in series with the variator and capable of switching a speed ratio depending on engagement and release of a plurality of friction elements;
• and
• shift control means for setting a final through speed ratio as a target speed ratio based on a driving condition of the vehicle and causing a through speed ratio, which is an overall speed ratio of the variator and the sub-transmission mechanism, to follow the final through speed ratio in a specified response by changing at least one of the speed ratio of the variator or a gear position of the sub-transmission mechanism,
• wherein the shift control means:
• has a manual mode in which a plurality of gear positions are set beforehand and a speed ratio corresponding to any one of the plurality of gear positions is set as the final through speed ratio based on a shift instruction from a driver;
• executes a control to cause the through speed ratio to follow the final through speed ratio by changing only the speed ratio of the variator if a shift instruction is given from the driver a plurality of times in a row when the manual mode is selected;
• and
• advances the start of a change in the speed ratio of the sub-transmission mechanism or accelerates the progression of the change of the speed ratio as compared with the case where the manual mode is not selected when the speed ratio of the variator is maximized or minimized and the through speed ratio cannot follow the final through speed ratio.