Dynamic load compensation method for an automatic transmission shift pattern

Abstract

An improved transmission shift pattern control that preserves the attributes of a selected base shift pattern while dynamically adjusting the high throttle shift thresholds based on a measure of vehicle loading. Heavy vehicle loading is detected by recognizing a pattern of high engine throttle and lower than expected vehicle acceleration, and the high power shifting thresholds are dynamically adjusted based on the detected loading to automatically provide aggressive shifting in a heavily loaded vehicle without producing excessive shift cycling in a normally or lightly loaded vehicle. A throttle timer is used to detect a condition of sustained high throttle operation, and under such condition, an acceleration timer determines the duration of lower than expected acceleration. If the determined duration exceeds a threshold, a shift pattern override is activated until the acceleration rises above an exit threshold. The severity of the loading condition may be determined with multiple acceleration timers used to activate successively more aggressive shift pattern overrides.

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