Modelling and Simulation of Shifting Processes of a Double Clutch Transmission
Modelling of a Double Clutch Transmission with an appropriate Controller for the Simulation of Shifting Processes with Modelica/Dymola
- © Henrik Isernhagen
Nowadays, more and more new cars are assembled
with double clutch transmission because of efficiency, drive comfort,
and uninterrupted power shifts. A double clutch transmission contains
two parallel transmission shafts with two parallel clutches. The
clutches can be either dry clutches or multi-disc (wet) clutches. The
different gears are mounted alternately on the two transmission
shafts. The first shaft contains the odd gears with the reverse gear,
and the second shaft contains the even gears. There are uninterrupted
power shifts possible by reason of the two different clutches with the
The correct control of the two clutches is very important in view to the different shifting processes. At this point it is necessary to distinguish between upshifts and downshifts as well as pulling power and pushing power of the powertrain. Controlling errors can result in bad shiftings, e. g., in form of revolution speed droppings, break outs, or oscillations.
In cooperation with the IAV GmbH  a software was developed for an automated analysis of vehicle measurement data . Here, recorded measurement data can be evaluated automatically to different system and failure states. The aim is to use this software to detect controlling errors of double clutch transmissions. Normally, data from the CAN-Bus would be analysed. But, the parametrisation of this analysis system requires measurement data of good and bad shifting processes.
Consequently, we develop different models of double clutch transmissions in Modelica/Dymola at the Department of Electronic Measurement and Diagnostic Technology. The aim of the modelling and simulation process is to get data of shift processes of different quality. For this it is necessary to build models with different levels of details. This task has to be differentiated between the physical modelling of the double clutch transmission and the modelling of the control structure. A basic model of a double clutch transmission and its insertion in the vehicle structure is shown in the cover figure. By varying the driver models it is possible to drive miscellaneous drive and shifting cycles, e. g., in form of a table with acceleration and brake pedal positions or following a velocity profile in form of predefined drive cycles.
Finally, the automated measurement data analysis system  should be parametrised using the simulation results. Beside the evaluation of shift processes it should be possible to analyse further control and measurement signals of double clutch transmissions. The aim is to use the measurement data analysis for the detection and assessment of bad shiftings in real vehicle measurement data.
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