Modelling and simulation of gear synchronisation and shifting in dual-clutch transmission equipped powertrains

Abstract

Dual-clutch transmissions have increased in prevalence through the combination of high efficiency and shift quality. This is achieved through the automation of conventional manual transmission synchronisers for gear selection with automated clutch-to-clutch shift control, minimising loss of traction to the road. This article derives a suitably detailed model of a dual-clutch transmission equipped powertrain for the transient simulation and analysis of combined synchroniser engagement and gear shifts. Models are derived for a powertrain equipped with a wet dual-clutch transmission with particular focus on a detailed synchroniser mechanism model, including speed synchronisation, ring unblocking and indexing stages of engagement. To demonstrate the combination of synchroniser engagement with clutch-to-clutch shifting, several simulations are conducted to study the variation of chamfer alignment, vehicle speed and synchroniser engagement timing on powertrain response. Results indicate that vehicle speed and chamfer alignment have only limited impact on the quality of shifting. Synchroniser timing can have a more significant influence on shift quality, stressing the need for independence of these processes.

Shift control of a dry-type two-speed dual-clutch transmission for an electric vehicle

“…In actual application, the clutch strokes are determined on the basis of maps which were constructed from experimental calibration work. [21][22][23] In this study, a clutch torque control algorithm is proposed as shown in Figure 13, which controls the clutch stroke with consideration of the torque margin and the KP during the torque phase. First, when the shift signal is given at point Q, S1_command is moved from the lock-up stroke LP1 to TS1, where the CL1 transfer torque is equal to the motor torque T m .…”

Two-Speed DCT Electric Powertrain Shifting Control and Rig Testing

“…The two clutches have a common drum attached to the input shaft from the motor, and the friction plates are independently connected to the first and second gears, respectively. With only two gear pairs and a final drive gear in the two-speed gearbox it is a comparatively simple transmission, without the requirement to engage alternate gears using synchronizer mechanisms [8,9]. For just two gear ratios, gear shifting is realized through dual clutch control alone.…”

“…The use of piecewise clutch models to account for transitions between dynamic and static frictions is performed by [2,8], where, upon clutch synchronization, an algorithm estimates the clutch torque and compares it to static friction to determine if friction lock is successful. A similar model is adopted by [4]; however the postlockup torque is not well defined.…”

A new control strategy of the filling phase for wet dual clutch transmission

“…1 Two clutches are used to alternate combination and separation, so the transmission can shift without power interruption. 2 The wet dual clutch transmission (WDCT) has been using the hydraulic actuator to control the gear shifting process, and the electro-hydraulic system description on the WDCT can be found in Jiang et al 3 and Lazar et al 4 In order to realize the smooth transition between two clutches, overlap process control is very important. Therefore, to ensure the precise control of the overlap process, the clutch packs are controlled to the position just in contact before the clutch engagement.…”