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Method and apparatus for speed change control of an automotive automatic transmission

  • US 5,435,796 A
  • Filed: 06/13/1994
  • Issued: 07/25/1995
  • Est. Priority Date: 04/15/1992
  • Status: Expired due to Fees
First Claim
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1. In an automotive automatic transmission including a first frictional engaging element for establishing a first gear stage, a second frictional engaging element for establishing a second gear stage, a first electromagnetic valve for controlling an operating oil pressure supplied to the first frictional engaging element, and a second electromagnetic valve for controlling an operating oil pressure supplied to the second frictional engaging element, a speed change control apparatus for controlling the first and second electromagnetic valves such that the first frictional engaging element, which has been engaged, is released, and the second frictional engaging element, which has been released, is engaged, to carry out a shift from the first gear stage to the second gear stage, said speed change control apparatus comprising:

  • first time measuring means for measuring a time period from the start of discharge of the operating oil pressure from the first frictional engaging element until a transmission torque through the first frictional engaging element becomes substantially zero;

    second time measuring means for measuring a time period from the start of supply of the operating oil pressure to the second frictional engaging element until a time point immediately before a time point at which torque is substantially transmitted through the second frictional engaging element; and

    control means for controlling the start of discharge of the operating oil pressure from the first frictional engaging element and the start of supply of the operating oil pressure to the second frictional engaging element, based on values detected by said first and second time measuring means, such that the time point at which the transmission torque through the first frictional engaging element becomes substantially zero coincides with the time point immediately before the time point at which torque is substantially transmitted through the second frictional engaging element.

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