A Digital Electronic Shift Schedule Control for Vehicular Automatic Transmissions

A digital transmission shift schedule control has been developed which measures throttle position and vehicle speed to determine the proper gear ratio based on preprogrammed upshift and downshift schedules.

Transmission pleasability was evaluated for various degrees of resolution for these two primary input variables. Five- and six-bit vehicle speed and three- and four-bit throttle position resolutions were tested. Throttle position was measured with an experimental variable reluctance (variable frequency oscillator) device, located above the throttle pedal; vehicle speed was measured by a magnetic pickup from a toothed wheel on the transmission output shaft.

The electronic control system has been evaluated for over 4000 miles under city, highway, sea level and high altitude conditions.