Importance

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Abstract

A control system and method for a power delivery system, such as in an automotive vehicle, having an engine coupled to a continuously variable ratio transmission (CVT). Totally 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. CVT ratio is controlled as a function of commanded desired system performance (e.g., power or torque) and measured actual system performance, such as CVT torque output, while engine fuel requirements (e.g., throttle position) are strictly a function of measured engine speed. Fuel requirements are therefore precisely adjusted in accordance with the ideal characteristics for any load placed on the engine. Appropriate controls prevent anomalous engine and vehicle behavior, and allow for transient start-up from rest. In a preferred embodiment a proportional controller is used to set the driving diameter of the driver sheave of a V-belt traction drive CVT, while the drive diameter of the driven sheave is controlled by a torque ramp.

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First Claim