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Electronic controller for a continuously variable transmission and a method of control of a continuously variable transmission

  • US 8,924,111 B2
  • Filed: 03/19/2009
  • Issued: 12/30/2014
  • Est. Priority Date: 03/20/2008
  • Status: Active Grant
First Claim
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1. An electronic controller for a continuously variable transmission comprising a variator which has a rotary variator input coupled to a first variator race, a rotary variator output coupled to a second variator race and at least one roller which runs upon the said races to transfer drive from one to the other, the roller(s) being movable to steplessly vary the variator ratio, the variator further comprising at least one hydraulic actuator which acts upon the roller(s) and through which net torque acting on the variator races is referred via the roller(s)to the variator'"'"'s casing, and a hydraulic arrangement for applying to the actuator(s) at least one hydraulic control pressure which determines force applied by the actuator(s) and thus determines the reaction torque, the variator being coupled between a rotary transmission input and a rotary transmission output such that the transmission ratio is a function of the variator ratio, the electronic controller being adapted to carry out the following in a loop:

  • measure a speed ratio of the continuously variable transmission;

    compare the measured speed ratio with a target speed ratio;

    determine a transmission output torque request on the basis of the said comparison;

    convert the output torque request to a control pressure request, taking account of the speed ratio;

    differentiate the control pressure request with respect to time to obtain a compensation value and apply the compensation value to the control pressure request; and

    output the resulting compensated control pressure request to the hydraulic valve arrangement.

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