Dynamic simulation of multi-plate clutches for automotive applications

Multi-plate clutches are used in various applications of automotive drivetrains. In comparison to conventional single plate clutches, they offer a higher torque transmission potential at lower actuation forces by a relatively small increase of installation space requirements. The transmittable torque of this clutch type is primarily determined by the number of so-called friction and steel plates. The plates have splines in order to guide them in the corresponding guide-ways when the clutch is actuated. The torque is transmitted by friction forces between the individual plates. Because of undesired friction in the guide-ways, the axial forces decrease from one plate to another, which leads to a lowered total torque transmission potential. In order to predict the behaviour and to understand the occurring phenomena of multi-plate clutches, comprehensive mechanical simulation is required.
The present paper introduces a simulation model, which is implemented in MATLAB Simulink with the target to cover motions and forces at every individual plate and to calculate the torque behaviour dynamically in real time domain, exemplary for dry multi-plate clutches. This kind of modelling represents a very challenging task as the motions are very small, the stiffness of the plates is very high and the friction forces and torques change very rapidly. Therefore appropriate friction models were sought and tested, which are on the one hand able to model the real frictional processes in the clutch and on the other hand can calculate the results in a fast and stable manner. With this approach it is possible to simulate the behaviour of a complete multi-plate clutch within acceptable simulation duration. By introduction of a new modelling strategy for multi-plate clutches in combination with enhanced simulation methods, a new approach is presented, that supports the layout and design of complex multi-plate clutch systems.