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An electronic controller for a continuously variable transmission and a method of control of a continuously variable transmission

An electronic controller, continuously variable speed technology, used in transmission control, transmission, friction transmission, etc.

Active Publication Date: 2011-02-16
ALLISON TRANSMISSION INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This is very challenging for tractors with torque controlled CVTs, where reaction torque must be adjusted rapidly in response to changes in wheel load in order to maintain the required ratio

Method used

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  • An electronic controller for a continuously variable transmission and a method of control of a continuously variable transmission
  • An electronic controller for a continuously variable transmission and a method of control of a continuously variable transmission
  • An electronic controller for a continuously variable transmission and a method of control of a continuously variable transmission

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Embodiment Construction

[0066] Figure 6 The system 110 shown in is compatible with torque control transmissions such as Figure 1 to Figure 4 as well as Figure 7 transmission shown in ) for use with a CVT. The system is used to determine a transmission control variable responsive to the magnitude of the sensed value and based on a proportional demand from the drive. In the broadest possible respect, the system can be considered to provide closed loop control based on the gear ratio error (ie, the difference between the actual gear ratio and the requested gear ratio).

[0067] The system repeatedly measures the current gear ratio. In principle, this can be achieved by measuring the transmission output speed and the transmission input speed and dividing one by the other. However, this method becomes less effective as the transmission output speed falls towards zero, and sensor noise can thus dominate the measured speed. The transmission output speed never approaches zero with the engine running,...

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Abstract

The invention concerns an electronic controller for a continuously variable transmission of the type having a variator (10) with a rotary variator input (17) coupled to a first variator race (14a) and a rotary variator output (29) coupled to a second variator race (16a). At least one roller (20) runs upon the said races to transfer drive from one to the other. The roller is movable to steplessly vary the variator ratio. The variator further comprises at least one hydraulic actuator (36), (38) which acts upon the roller and through which net torque acting on the variator races is referred via the roller to the variator' s casing. A hydraulic arrangement is provided for applying to the actuator at least one hydraulic control pressure which determines force applied' by the actuator and thus determines the reaction torque. The varialtor is coupled between a rotary transmission input (17) and a rotary transmission output (714) such that the transmission ratio is a function of the variator ratio. The electronic controller is adapted to cany out the following steps 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 lime to obtain a compensation value and apply the compensation value to the control pressure request; and output the resulting compensated control pressure reqxiest to the hydraulic valve arrangement.

Description

technical field [0001] The invention relates to the control of a continuously variable transmission (CVT, Continuously Variable Transmission). The invention is particularly, but not exclusively, suitable for controlling continuously variable transmissions of motor vehicles at low vehicle speeds. Background technique [0002] A CVT generally includes a unit called a "variator" that has a rotary variator input, a rotary variator output, and a mechanism for transferring power from one to the other, while the variator makes the difference between the output speed and the input speed The ratio (gear ratio) can be changed steplessly. [0003] A typical CVT also includes gearing by which the transmission is coupled between a general transmission input (eg, the drive shaft of a vehicle's engine) and an output (eg, the vehicle's final drive leading to its wheels). The ratio of the speed of the transmission output to the input (gear ratio) is usually not the same as the transmission...

Claims

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Application Information

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IPC IPC(8): F16H61/664F16H15/38
CPCF16H61/6648F16H15/38
Inventor 约翰·威廉·爱德华·富勒
Owner ALLISON TRANSMISSION INC
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