Modelling and simulation of friction disc clutch operation in automatic transmission

Abstract

Friction disc clutches and brakes have very important role in quality of gear shifting. Thus, it is necessary that they have electric-hydraulic control and stable characteristics, which depend on a type of a friction material. Also, it is necessary that they have sufficient heat capacitance in order to be able to resist high operation temperatures during gear shifting. By application of friction disc clutches and brakes in automatic transmissions, gear shifting under load is achieved without power flow interruption. Gear shifting time is considerably reduced, driver's load is decreased and the task of gear shifting is simplified. One of the heaviest and the most important tasks of the system for gearbox automatic control are to provide continuos engagement of friction clutches and brakes. If this task is not successfully resolved, there are some interruptions in vehicle's operation and it makes its exploitation more difficult and causes dynamic loads of vehicle's transmission and engine. This paper presents a mathematical model of engagement of disc clutches and brakes during gear shifting from higher to lower level, as well as the results of simulation performed by MATLAB-Simulink computer program.