Outline of a New Control Concept for Power Shifting of Fixed Step Ratio Automotive Transmissions
Journal article, 2001
Power shifting transmissions, e.g. automatic transmissions, are traditionally shifted from gear A to B by disengaging a clutch belonging to gear A and engaging a clutch belonging to gear B. This paper tries out the idea of employing a third clutch. In practice, such a third clutch can be one of the clutches which is traditionally used only for other gears. This means that the new concept can be used with only a control software update in an ordinary gearbox. The trade-off between comfort and wear, which is experienced in the traditional control concept, becomes less troublesome. The wear, or the discomfort, can be reduced to roughly half of that corresponding to a traditionally controlled upshift. The work finds the largest potential in using an extra clutch which belongs to a gear higher than the high gear in an upshift. The theoretical study is carried out with a general and simple model, but a simulation example is added using a more detailed model of an existing gearbox.