METHOD AND APPARATUS FOR ASSISTING IN SHIFTING TRANSMISSION TO NEUTRAL

摘要

An operator of a vehicle may request torque reduction on the connection between a transmission and an engine, or may use a clutch. A switch is provided to send a torque elimination request. Upon receiving the request, an engine control adjusts engine fueling to achieve a zero torque load on a transmission to allow an operator to shift the transmission to neutral without clutching. The engine control predicts the engine fueling to achieve a zero torque load, and begins adjusting fueling to approach that predicted value. The prediction of the zero torque value is based on system variables other than torque load. Since the actual zero torque fueling varies, it is difficult to measure or predict. Moreover, a torque meter for measuring actual torque is expensive and difficult to maintain. The present invention addresses this difficulty by adjusting the engine fueling above and below the predicted zero torque value. In this way, the actual engine fueling will repeatedly cross the actual zero torque value such that the operator will be able to move the transmission out of gear to a neutral position.