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Downshift control for automotive automatic transmission

  • US 20060040791A1
  • Filed: 08/19/2005
  • Published: 02/23/2006
  • Est. Priority Date: 08/19/2004
  • Status: Active Grant
First Claim
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1. An automatic transmission control apparatus comprising:

  • a hydraulic control circuit which controls hydraulic pressures to be applied to a plurality of frictional elements of an automatic transmission joined to an engine to selectively achieve engagement and disengagement of the frictional elements for establishing a required speed of the automatic transmission;

    a defect detector working to detect a defect of said hydraulic control circuit;

    an engine output increasing circuit designed to perform engine output increasing control to increase an output of the engine upon a downshift of the automatic transmission to develop engine braking in response to a request from an operator to decelerate a speed of the automatic transmission, said engine output increasing circuit initiating the engine output increasing control within an interval between start to control the hydraulic pressures through said hydraulic control circuit to achieve the downshift and start of an actual shift in speed of the automatic transmission; and

    a fail-safe circuit working to stop the engine output increasing control when said defect detector detects the defect of said hydraulic control circuit after said hydraulic control circuit starts to control the hydraulic pressures to achieve the downshift of the automatic transmission.

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