A New Control Strategy of Wet Dual Clutch Transmission (DCT) Clutch and Synchronizer for Seamless Gear Preselect

In this paper, a new gear preselect strategy of wet dual clutch transmission (DCT) is proposed by delaying the gear preselect to the time near the power shift time in order to create a seamless gear preselect. Software in the loop (SiL) method is used to investigate the proposed strategy. High fidelity 13 degree of freedom lumped inertia drivetrain models, i.e., synchronizer model and electro hydraulic model, are constructed and validated using laboratory test data. A closed loop control for electro hydraulic system is developed to control the clutch and synchronizer considering the optimum synchronizer trigger time. Furthermore, the model used in this study is constructed considering the valve spool dynamic in electro hydraulic system and the sleeve dynamic including axial drag force in synchronizer system. The genetic algorithm has been used to obtain the optimum trigger time which is close to the power shift time to sustain uninterrupted torque during gear shifting. A comparison between the conventional sport mode gear preselect strategy with the proposed gear preselect strategy is performed. The obtained results of the proposed strategy show a fuel reduction of 0.8% in New European Driving Cycle (NEDC), within the allowable limits of the shift time.