Outline of a new control concept for power shifting of fixed step ratio automotive transmissions

Power shifting transmissions, e.g. automatic transmissions, are traditional ly 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 em ploying 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 ordin ary gearbox. The trade-off between comfort and wear. which is experienced i n the traditional control concept, becomes less troublesome. The wear, or t he discomfort, can be reduced to roughly half of that corresponding to a tr aditionally controlled upshift. The work finds the largest potential in usi ng 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 mod el. but a simulation example is added using a more detailed model of an exi sting gearbox.