Fuel consumption and driveline efficiency are important issues in the automotive industry. Continuously Variable Transmission s(CVT) can cover a wide range of ratios which makes it possible to operate a combustion engine in more efficient working points than stepped transmissions. The main reason for the low efficiency of modern production CVT are the high clamping forces in the variator necessary to prevent belt slip. In this paper, a method is presented to measure and control slip in a modern production CVT. The Jatco CK2 is used for testing, which is based on the metal push belt from Van Doorne's Transmissie (VDT). An increase in torque in the variator will lead to more slip. When the slip level remains in the microslip region, an increase in slip will also lead to an increasing traction coefficient, thus allowing the higher torque to be transmitted. In the macroslip region however, slip will increase drastically if no action is taken when the torque increases. Using slip control, the clamping forces are actively controlled to maximize the efficiency of the CVT. This is achieved by maintaining an amount of slip, where the traction coefficient is near its maximum. This means that the slip is controlled in the transition area of the micro- and macroslip regions. An increase in the torque level will lead to an increase in beltslip, but by adjusting the clamping force fast enough the slip will not reach destructive levels and therefore damage can be avoided. The most important requirement of the slip controller is the ability to attenuate the load disturbances caused by torque peaks in the driveline. To meet all requirements, a synthesis model for robust PI(D)-controllers with optimal load disturbance response is used. The slip controller is simulated and tested on a test rig that is equipped with a 2.0-l internal combustion engine, a flywheel, and eddy-current brake and a disc brake to simulate realistic road loads.
LPV control of slip in a pushbelt-type variator. Slip control implemented in an Audi A3
2005
13 Seiten, 11 Bilder, 1 Tabelle, 7 Quellen
Conference paper
English
LPV control of slip in a pushbelt type variator : Slip control implemented in an Audi A3
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