Learned N/V ratio electronic control for automatic transmission reference speed in a driveline having unknown axle ratio

摘要

An electronic control system for scheduling gearshifts in a four speed automatic transmission includes storing in electronic memory accessible to a microprocessor, six functions relating vehicle speed to throttle position, one function being related to each upshift and downshift. Gearshifts are made by probing computer memory with current values for throttle position and vehicle speed, and determining on the basis of the stored shift schedule whether an upshift of downshift is required. Upshift points are determined also on the basis of the maximum engine speed when a wide open throttle condition is detected. Electronic memory continually accessible to the microprocessor is updated with new calculated values of the ratio NOV divided by base NOV. Vehicle speed from a stored schedule of gearshift values is corrected with the calculated ratio to account for changes in the driveline components from their condition when originally installed and differences from a calculated base NOV value.