Importance

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Abstract

A control system and method for a power delivery system, such as that of an automotive vehicle, having an engine coupled to a continuously variable ratio transmission (CVT). Independent control of engine and transmission enable the engine to precisely follow a desired operating characteristic, such as the ideal operating line for low fuel consumption. Engine fuel requirements (e.g., throttle position) are a function of at least measured engine speed, and are adjusted in accordance with any load placed on the engine so that, during low power operation, fuel flow is increased when a decrease in operating speed occurs, and fuel flow is reduced when an increase in operating speed occurs. The speed of the engine is therefore regulated in accordance with the load placed thereon. Reduction of transmission ratio effects vehicle acceleration in this mode, while an increase in transmission ratio effects vehicle deceleration. Where a clutch or other type of variable engagement coupling is employed, the engine still is independently regulated in accordance with the fuel function even when the clutch is slipping. During the clutch slipping phase, the transmission preferably is held at a substantially constant high reduction ratio, while vehicle acceleration and deceleration are effected simply by varying the degree of engagement of the clutch.

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First Claim