This paper presents a feedback control strategy aimed to reduce noise and wear
during gearshifts in conventional and hybrid Dual Clutch Transmissions (DCT and
DCTH) and Automated Manual Transmissions (AMT). The control strategy is based on
a new dog teeth position sensor developed by China Euro Vehicle Technology AB
and existing speed sensors in the transmission. During gear shifting, noise is
generated by impacts between the sleeve teeth and the idler gear dog teeth after
speed synchronization. Besides noise, these impacts are also responsible for
delaying the completion of shift and contribute to wear in the dog teeth, hence
reducing the lifespan of the transmission. The presented control strategy
controls speed synchronization such that the impact between sleeve and idler
gear dog teeth, before the start of torque ramp up, is avoided. Since drag
torque is an important factor in speed synchronization, this paper also contains
an algorithm to identify friction torque coefficient in the transmission. The
identification method ensures that the controller adapts to varying conditions
without the need for offline calibration. The control strategy is developed for
standard automatic gear shifting operations but minor adaptations in the
algorithm also make it capable of handling gear shifts requested by the driver.
The output signal of the control strategy is acceleration request on idler gear
during speed synchronization. To make controller easier to implement and
minimize shift time, the acceleration request only has two values, either
maximum value or zero. The control strategy is designed in such a way that it
can easily be integrated in the existing transmission control software. By
applying the control strategy on a detailed simulation model, it is shown that
the impacts during gear engagement are significantly reduced.
