Control apparatus for continuously variable transmission

摘要

In an apparatus for controlling a continuously variable transmission, a transmission ratio, an input shaft rotational speed and an input torque, etc., are detected, an axial thrusts of the drive and driven pulleys are detected therefrom, an inter-shaft force is detected, a friction coefficient of the driven pulley including at least a radial component of the friction coefficient μRDN is calculated in accordance with predetermined relational equations, a target axial thrust of the driven pulley is calculated based on at least the friction coefficient and the axial thrust of the driven pulley is controlled based on the calculated target axial thrust.

主权项

1. An apparatus for controlling a continuously variable transmission having a drive pulley mounted on an input shaft connected to a prime mover mounted on a vehicle, a driven pulley mounted on an output shaft connected to driven wheels and a power transmissible member wound around the drive and driven pulleys to be clamped therebetween in response to axial thrust acting along axes of the input and output shafts, comprising:
a transmission operating state detection block that detects parameters including at least a transmission ratio, a rotational speed of the input shaft and an input torque indicative of operating state of the transmission; an axial thrust detection block that detects the axial thrusts of the drive and driven pulleys; an inter-shaft force detection block that detects an inter-shaft force indicative of a force which pulls the input shaft and the output shaft against each other; a friction coefficient calculation block that calculates a friction coefficient of the driven pulley including at least a radial component of the friction coefficient in accordance with predetermined relational equations based on the detected operating state, axial thrust and inter-shaft force; a target axial thrust calculation block that calculates a target axial thrust of the driven pulley based on at least the calculated friction coefficient; and an axial thrust control block that controls the axial thrust of the driven pulley based on the calculated target axial thrust, wherein the friction coefficient calculation block calculates the radial component of the friction coefficient and a tangent component of the friction coefficient of the driven pulley in accordance with the predetermined relational equations, calculates an average friction coefficient of the driven pulley from the calculated radial component of the friction coefficient and the tangent component of the friction coefficient, and calculates a maximum tangent component of the friction coefficient of the driven pulley indicative of a friction coefficient just before the member slips from the driven pulley from the calculated average friction coefficient based on predetermined characteristics, and the target axial thrust calculation block calculates the target axial thrust based on at least the calculated maximum tangent component of the friction coefficient.