Importance

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Abstract

A method and a circuit for determining the optimum gear, in terms of fuel consumption, of a motor vehicle drive is proposed, in which after upshifting, a driving power sufficient for accelerating the vehicle is to be made available regardless of such power parameters as total vehicle weight, roadway grades and the like and also regardless of the gear ratios of the gear steps. To this end, during driving, the gear ratios of the gear steps are ascertained by comparing the speeds (n, n.sub.1) before and after the transmission (12). Furthermore, these speed values (n, n.sub.1) as well as the gas pedal position (.phi.) are continuously stored briefly in memory during the drive, and a standardized power is ascertained based on the change in the driving speed (n.sub.1). After a gear shifting operation, the newly ascertained standardized power is compared with the standardized power ascertained prior to shifting, and if the new standardized power is the same or greater, the values for the driving speed (n.sub.1) and gas pedal position (.phi.) measured prior to the upshifting are recorded in a threshold value memory (24). An upshifting indication is always effected whenever the instantaneous measured values (n.sub.1, .phi.) exceed the stored threshold values in the direction of an unfavorable operating range in terms of fuel consumption. The method is applicable to both Diesel and gasoline engines as well as to large and small motors and to any arbitrary, but fixed, gear step ratios.

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First Claim