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Automatic transmission shift stabilization control

  • US 5,685,799 A
  • Filed: 07/01/1996
  • Issued: 11/11/1997
  • Est. Priority Date: 07/01/1996
  • Status: Expired due to Term
First Claim
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1. A method of preventing shift cycling between numerically adjacent speed ratios in a motor vehicle powertrain including an engine imparting torque through a torque converter to the input of an automatic transmission having a plurality of speed ratios selectively engaged in accordance with a shift schedule comprising predetermined relationships between throttle position and powertrain output speed, said automatic transmission operatively coupling an output torque to at least one drive wheel, the method comprising the steps:

  • monitoring powertrain output speed;

    monitoring throttle position;

    while a first one of said plurality of speed ratios is engaged, detecting an upshift condition with respect to the shift schedule normally effective to schedule upshifting to a second one of the plurality of said speed ratios;

    providing a minimum post-shift output torque requirement;

    providing a maximum post-shift output torque substantially equivalent to output torque sustainable at a predetermined powertrain output speed before a downshift condition would be detected assuming the second one of the plurality of speed ratios was engaged; and

    ,inhibiting an upshift to the second one of the plurality of speed ratios regardless of said detected upshift condition when the maximum post-shift output torque is less than the minimum post-shift output torque requirement.

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