Engine speed retardation on transmission upshift

Abstract

An improved engine control provides rapid decrease in the output speed of the engine when an upshift of the transmission is being actuated. The system selectively actuates a speed retardation system to decrease the engine output speed to match a desired engine output speed at the next highest gear ratio. In one embodiment, an engine control actuates engine braking to achieve this rapid speed reduction. In other embodiments, an additional load may be placed on the engine, such as the actuation of a fan. An operator is preferably provided with a shift intent switch that provides an indication to the engine control that an upshift will be actuated. The engine control waits for an indication that the transmission has been moved to neutral. Once this indication is received, the speed retardation system is actuated to rapidly reduce the engine output speed toward a desired value. Most preferably, this feature is incorporated into an engine control system adapted to synchronize the engine output speed to that desired at the next gear ratio, both when the transmission is being upshifted or downshifted. The engine control system allows an operator to achieve a transmission shift without complicated clutching of the transmission.