# Traction curve measurements with controlled ratio

Authors
Publisher
Technische Universiteit Eindhoven
Publication Date
Source
Legacy
Keywords
• Mechanical Engineering: Report Series
• Power Transmissions
• Automatic Transmissions
Disciplines
• Mathematics

## Abstract

Traction curve measurements with controlled ratio R.G.J. Drabbels DCT 2004.22 Traineeship report Coach(es): ir. B. Bonsen Supervisor: prof. ir. N.J.J. Liebrand Technische Universiteit Eindhoven Department Mechanical Engineering Dynamics and Control Technology Group Eindhoven, July, 2004 TUfe Abstract Traction curve measurements with controlled ratio In a continuously variable transmission (CVT), the so-called traction curve is the dimensionless relationship between the transmitted torque, represented by the traction coefficient, and the slip. In order to measure this relationship, a control strategy is determined to measure and control the slip. The geometrical ratio is controlled with a pressure control system that uses a position sensor on the CVT housing, which measures the secondary pulley position. The intention was to be able to measure complete traction curves at any desired geometrical ratio. However, only the measurements in the extreme pulley position ratios low and overdrive provide the desired results. In intermediate ratios the system becomes unstable at slip values higher than approximately I%. The traction curves in low and overdrive ratios largely correspond with what is expected from literature and previous measurements. It appeared that the traction coefficient is smaller at higher speeds, and the variator efficiency decreases with increasing speed. I TUfe Table of Contents Traction curve measurements with controlled ratio ABSTRACT 1 1 INTRODUCTION 3 2 TORQUE TRANSMISSION 4 2.1 TRACTION CURVE 4 2.2 SLIP 5 2.3 EFFICIENCY 5 3 EXPERIMENTAL SETUP 6 3.1 TEST RIG 6 3.2 PRESSURE CONTROL 7 3.3 SLIP CONTROL 8 3.4 CONTROL SCHEME 9 4 RESULTS 10 4.1 MEASUREMENTS 10 4.2 TRACTION CURVE 10 4.3 EFFICIENCY 13 5 CONCLUSIONS AND RECOMMENDATIONS 16 REFERENCES 17 APPENDIX I: THE MATLAB-SIMULINK SCHEME 18 2 TUfe Traction curve measurements with controlled ratio 1 Introduction In comparison with the still more common stepped transmI

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