Driving aid indicator for economical operation of automatic transmission

Abstract

Driving aid apparatus for determining the best, most economical operating conditions for a motor vehicle equipped with an automatic transmission. The input member rotational rate of a torque converter coupled with the automatic transmission is measured. The rotational rate of the output member of the torque converter is also measured. A distinct difference may normally exist between these two rates, when a load is applied to the torque converter output, due to 'slip' through the torque converter. The extent of this slip is in part proportional to the torque transmitted through the torque converter and, therefore, by a determination made from the difference between the two rates in combination with other key parameters affecting torque converter performance, the relative engine output torque can be found. Through utilizing this relative torque factor, in combination with other engine parameter signals such as manifold vacuum, operating temperature, and throttle position, the relative operating steadiness and net efficiency of the instant operating conditions of the overall vehicle is derived and displayed for the driver. This display enables the driver to operate the vehicle in a manner leading to uniform performance and maximum fuel economy. Through a control available for driver adjustment, the computed indicator responses are further modified to best suit the driving habits of the driver. A unique vehicle performance profile memory adds the dimension of tailoring the computed responses to the exact performance characteristics of the attendant vehicle.