Nonlinear dynamics of controlled slipping clutches.

摘要

In this research, the nonlinear dynamics of a slip-controlled torque converter clutch (TCC) system has been studied. Equilibrium continuation of a system model, with conventional, or simple proportional-integral (PI) action for TCC slip control, reveals loss of stability via Hopf bifurcations when the P-gain (Kp) is increased or when the friction gradient (m) is decreased. Higher Kp values can be tolerated at high slip speeds or at high engine torques. Better tolerance of negative m values is seen at high slip speeds, low engine torques and high static friction coefficient (mu s) values. Higher Kp values also have adverse effects on the vibration response of the system. Higher engine torques, higher engine speeds and higher number of engine cylinders help in lowering the vibration amplitude of the driveline elements. CL_MATCONT, a Matlab based toolbox, has been implemented for numerical continuation and bifurcation analysis. The results of CL_MATCONT have been validated using OP_CONBIF, a Matlab script developed based on one-parameter equilibrium continuation theory, and by means of simulations. Vehicle events such as gear shift, sudden change in acceleration and changes in road conditions have also been simulated to check the performance of the simple PI-based TCC slip control system.; An adaptive PI-based TCC slip control methodology, based on Lyapunov theory, has been proposed. Improved stability domain is achieved by implementing the adaptive control approach. Equilibrium continuation with m as the bifurcation parameter reveals that better tolerance of negative friction gradient (or negative m values) is observed as compared to the simple PI-based TCC slip control system.