Control system for continuously variable transmission

Claim 1

An apparatus comprising: a continuously variable transmission having at least one pair of traction rollers; and a system for controlling said continuously variable transmission such that the continuously variable transmission is adjusted to a reduction ratio that is determined in response to a position at which a shift actuator is positioned, the system comprising means for determining a target value of a predetermined variable related to a reduction ratio which the continuously variable transmission should be adjusted to and for generating a target value indicative signal indicative of said target value determined; means for detecting a current value of said predetermined variable and for generating a current value indicative signal indicative of said current value detected; means for detecting a current torque which the continuously variable transmission is subject to and for generating a current torque indicative signal indicative of said current torque detected; means for controlling the shift actuator in a feed-back control manner with a feed-back gain such that a deviation between said current value indicative signal and said target value indicative signal reduces toward zero; means for altering said feed-back gain in response to said current torque indicative signal; and shift control valve means for controlling a distribution of hydraulic pressure related to said reduction ratio in response to the position at which the shift actuator is positioned.

Claim 2

An apparatus comprising: a continuously variable transmission having at least one pair of traction rollers; and a system for controlling said continuously variable transmission such that the continuously variable transmission is adjusted to a reduction ratio that is determined in response to a position at which a shift actuator is positioned, the system comprising means for determining a target value of a predetermined variable related to a reduction ratio which the continuously variable transmission should be adjusted to and for generating a target value indicative signal indicative of said target value determined; means for detecting a current value of said predetermined variable and for generating a current value indicative signal indicative of said current value detected; means for detecting a current torque which the continuously variable transmission is subject to and for generating a current torque indicative signal indicative of said current torque detected; means for controlling the shift actuator in a feed-back control manner with a feed-back gain such that a deviation between said current value indicative signal and said target value indicative signal reduces toward zero; means for altering said feed-back gain in response to said current torque indicative signal; and shift control valve means for controlling a distribution of hydraulic pressure related to said reduction ratio in response to the position at which the shift actuator is positioned.

Claim 3

A method of controlling a continuously variable transmission such that the continuously variable transmission is adjusted to a reduction ratio that is determined in response to a position at which a shift actuator is positioned, the continuously variable transmission having at least one pair of traction rollers, the method comprising the steps of: determining a target value of a predetermined variable related to a reduction ratio which the continuously variable transmission should be adjusted to and generating a target value indicative signal indicative of said target value determined; detecting a current value of said predetermined variable and generating a current value indicative signal indicative of said current value detected; detecting a current torque which the continuously variable transmission is subject to and generating a current torque indicative signal indicative of said current torque detected; controlling the shift actuator in a feed-back control manner with a feed-back gain such that a deviation between said current value indicative signal and said target value indicative signal reduces toward zero; altering said feed-back gain in response to said current torque indicative signal; and controlling a distribution of hydraulic pressure related to said reduction ratio in response to the position at which the shift actuator is positioned.

Claim 4

A method of controlling a continuously variable transmission such that the continuously variable transmission is adjusted to a reduction ratio that is determined in response to a position at which a shift actuator is positioned, the continuously variable transmission having at least one pair of traction rollers, the method comprising the steps of: determining a target value of a predetermined variable related to a reduction ratio which the continuously variable transmission should be adjusted to and generating a target value indicative signal indicative of said target value determined; detecting a current value of said predetermined variable and generating a current value indicative signal indicative of said current value detected; detecting a current torque which the continuously variable transmission is subject to and generating a current torque indicative signal indicative of said current torque detected; controlling the shift actuator in a feed-back control manner with a feed-back gain such that a deviation between said current value indicative signal and said target value indicative signal reduces toward zero; altering said feed-back gain in response to said current torque indicative signal; and controlling a distribution of hydraulic pressure related to said reduction ratio in response to the position at which the shift actuator is positioned.