Compensation for delay of scheduled gearshifts in automatic transmissions

  • US 5,233,523 A
  • Filed: 12/21/1990
  • Issued: 08/03/1993
  • Est. Priority Date: 12/21/1990
  • Status: Expired due to Fees
First Claim
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1. A system for controlling gearshifts in an automatic multiple gear ratio transmission for an automotive vehicle having an engine controlled by a variable position throttle, comprising:

  • multiple ratio gearing and pressure-operated friction elements selectively engaged and released to produce multiple gear ratios through said gearing;

    a hydraulic circuit having multiple shift control valves for selectively engaging and releasing said friction elements;

    means for determining current vehicle speed and current vehicle longitudinal acceleration;

    means for determining the currently engaged gear;

    means for retaining a predetermined gearshift schedule relating current throttle position and current vehicle speed, the schedule defining, for each current gear, a range of operating conditions established by paired values of current throttle position and current vehicle speed, each range extending between an upshift boundary at which an upshift is permitted from each current gear and a downshift boundary at which an downshift is permitted from each current gear;

    means for retaining a predetermined delay variable associated with upshifts and downshifts from a current gear;

    means for determining an adjusted vehicle speed from current vehicle speed, vehicle acceleration and a delay variable for said change of gear;

    means for commanding a change of gear from the current gear if a boundary of the gearshift schedule for the current gear is crossed due to a change of operating condition defined by paired values of adjusted vehicle speed and current throttle position; and

    means for producing a gearshift by selectively engaging and releasing the friction elements in response to the gearshift command.

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