Simulation of a Pressure-Controlled Clamping System for Continuously Variable Belt- and Chain Transmissions

Abstract

The transmittable power of continuously variable belt- and chain trans- missions has been steadily increased in recent years so that they can be used on tractors of the lower and medium power classes. In the current common designs, the hydraulic system, which is required for clamping and adjustment, exerts a strong influence on the total losses. In order to increase the overall efficiency of such a transmission, new, pressure- controlled clamping hydraulics with significantly higher system-related efficiency were examined with the aid of computer simulation. These stu- dies focused on the realization of highly dynamic clamping pressure supply in cases of sudden torque increase, which occur frequently in tractors. For the optimization of efficiency, excess clamping must be avoided. For further examinations, a real-time simulation system was set up which, in addition to measurement data collection on the test bench, allows for the speedy and efficient development of control strategies.