Simulations of drag torque affecting synchronisers in a dual clutch transmission

摘要

Drag torque contributes significantly to the engagement of synchronisers in vehicle transmissions. Little is understood of how drag torque varies during transient engagement. Considerable analysis, however, has shown it affects engagement and can cause the mechanism to fail. To demonstrate the significance of the role that drag torque plays during synchroniser engagement in a wet clutch dual clutch transmission numerical models of the mechanism and drag torque are developed. This includes torsional resistances from bearings, gear windage and friction, viscous shear in the concentrically aligned shafts and the wet clutch pack. Simulations are performed in Matlab (R) to evaluate the drag torques acting on the mechanism. The results of simulations using this model demonstrate that the drag torque is dominated by the viscous drag in the wet clutch. Furthermore simulations demonstrate the nonlinear nature of this torque, and the peak drag torque is identified as being significantly larger that typical estimations.