Controller for continuously variable transmission

摘要

A controller for a continuously variable transmission includes an electronic control unit. The electronic control unit reduces a change in a target speed ratio of the continuously variable transmission when a sensitivity coefficient is large as compared to when the sensitivity coefficient is small. When the sensitivity coefficient is large, a change in speed ratio is suppressed, so the stability of the speed ratio is improved. When the sensitivity coefficient is small, the response of a shift is improved. The controller changes a degree of suppressing a shift of the continuously variable transmission in response to the sensitivity coefficient, so it is possible to suppress a shift where necessary. Thus, it is possible to achieve both improvement in the stability of the speed ratio and improvement in the response of a shift in automatic vehicle speed control. This suppresses a feeling of strangeness experienced by a driver.

主权项

1. A controller for a continuously variable transmission, the continuously variable transmission being configured to transmit power of an engine to a drive wheel side, the controller comprising:
an electronic control unit configured to, in automatic vehicle speed control for controlling an actual vehicle speed irrespective of a required power amount based on driver's operation,
(i) calculate a target driving force, by which the actual vehicle speed is controlled, based on a set target vehicle speed,(ii) calculate a target engine torque by which the target driving force is achieved,(iii) calculate a speed ratio control required power amount, by which the target engine torque is obtained,(iv) calculate a target speed ratio of the continuously variable transmission based on the speed ratio control required power amount,(v) calculate a sensitivity coefficient based on the target engine torque and a target engine rotation speed, the sensitivity coefficient being a degree of a change in the speed ratio control required power amount to a change in the target engine torque, and(vi) reduce a change in the target speed ratio of the continuously variable transmission when the sensitivity coefficient is large as compared to when the sensitivity coefficient is small.