Control device for continuously variable transmission equipped with auxiliary transmission

1. A control device for a continuously variable transmission with an auxiliary transmission which is mounted to a vehicle, and which includes a variator arranged to continuously vary a transmission gear ratio, and an auxiliary transmission mechanism that is disposed in series with the variator, and that has a first shift stage being a forward shift stage, and a second shift stage being the forward shift stage, and having a transmission gear ratio smaller than a transmission gear ratio of the first shift stage, the control device comprising:

a cooperative control section configured to perform a cooperative control to shift the auxiliary transmission mechanism, and to shift the variator in a direction opposite to a shift direction of the auxiliary transmission mechanism when the shift stage of the auxiliary transmission mechanism is varied,

the cooperative control section including an inertia phase time period setting control section configured to set a first inertia phase time period which is a cooperative shift inertia phase time period of an overall transmission, and a second inertia phase time period which is shorter than the first inertia phase time period,

the cooperative control section being configured to shift the auxiliary transmission mechanism during the first inertia phase time period, and to shift the variator during the second inertia phase time period, when the cooperative control in which an input torque to the continuously variable transmission is equal to or smaller than a predetermined value in the cooperative control is judged, and

the cooperative control section being configured to shift the auxiliary transmission mechanism during the first inertia phase time period, and to shift the variator during the first inertia phase time period when the cooperative control in which the input torque to the continuously variable transmission is greater than the predetermined value is judged.

2. The control device for the continuously variable transmission with the auxiliary transmission as claimed in claim 1 , wherein the inertia phase time period setting section is configured to set the second inertia phase time period which is shorter than the first inertia phase time period when a progress speed of the shift of the variator is slower than a progress speed of the shift of the auxiliary transmission, and the vehicle is in a driving region when an input rotation speed to the continuously variable transmission is decreased.

3. The control device for the continuously variable transmission with the auxiliary transmission as claimed in claim 1 , wherein the cooperative control section is configured to perform an input rotation speed increase suppressing control in which an engagement force of an engagement side frictional engagement element is increased when an increase of an input rotation speed to the continuously variable transmission is sensed during the cooperative control in which the auxiliary transmission mechanism is shifted during the first inertia phase time period, and the variator is shifted during the second inertia phase time period.

4. A control device for a continuously variable transmission with an auxiliary transmission which is mounted to a vehicle, and which includes a variator arranged to continuously vary a transmission gear ratio, and an auxiliary transmission mechanism that is disposed in series with the variator, and that has a first shift stage being a forward shift stage, and a second shift stage being the forward shift stage, and having a transmission gear ratio smaller than a transmission gear ratio of the first shift stage, the control device comprising:

a transmission controller configured to

perform a cooperative control to shift the auxiliary transmission mechanism, and to shift the variator in a direction opposite to a shift direction of the auxiliary transmission mechanism when the shift stage of the auxiliary transmission mechanism is varied,

set a first inertia phase time period which is a cooperative shift inertia phase time period of an overall transmission, and a second inertia phase time period which is shorter than the first inertia phase time period,

cause the auxiliary transmission mechanism to shift during the first inertia phase time period, and cause the variator to shift during the second inertia phase time period, when the cooperative control in which an input torque to the continuously variable transmission is equal to or smaller than a predetermined value in the cooperative control is judged, and

cause the auxiliary transmission mechanism to shift during the first inertia phase time period, and cause the variator to shift during the first inertia phase time period when the cooperative control in which the input torque to the continuously variable transmission is greater than the predetermined value is judged.

5. The control device for the continuously variable transmission with the auxiliary transmission as claimed in claim 4 , wherein the transmission controller is further configured to set the second inertia phase time period which is shorter than the first inertia phase time period when a progress speed of the shift of the variator is slower than a progress speed of the shift of the auxiliary transmission, and the vehicle is in a driving region when an input rotation speed to the continuously variable transmission is decreased.

6. The control device for the continuously variable transmission with the auxiliary transmission as claimed in claim 4 , wherein the transmission controller is further configured to perform an input rotation speed increase suppressing control in which an engagement force of an engagement side frictional engagement element is increased when an increase of an input rotation speed to the continuously variable transmission is sensed during the cooperative control in which the auxiliary transmission mechanism is shifted during the first inertia phase time period, and the variator is shifted during the second inertia phase time period.