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Forward drive release system for automatic transmission

  • US 4,514,811 A
  • Filed: 06/28/1982
  • Issued: 04/30/1985
  • Est. Priority Date: 06/28/1982
  • Status: Expired due to Term
First Claim
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1. A control system for controlling the magnitude of torque transmitted through a clutch of an automatic transmission comprising:

  • a throttle sensor which generates a signal that represents the throttle opening of a throttle controlled engine;

    an engine speed sensor which detects a value that represents the engine rotational speed, NE;

    a gear ratio sensor which generates a signal that represents disposition of the gear selector in a forward drive position;

    a shaft speed sensor which generates a signal that represents the speed of the vehicle;

    a torque converter having an impeller drivably connected to the engine crankshaft and a turbine driven from the impeller;

    a turbine speed sensor which generates a value that represents the turbine speed, NT;

    a solenoid operated valve that opens and closes communication between a source of pressurized fluid and the clutch and between atmosphere and the clutch, thereby pressurizing and venting the clutch as the solenoid windings are energized and deenergized;

    computing means for repetitively computing the duty cycle of the solenoid provided the gear ratio selector is disposed and in an acceptable forward drive position, the throttle setting is equal to or less than a predetermined setting and the vehicle speed is equal to or less than a predetermined speed, having a data base that includes the values of the proportional gain, KP, the derivative gain, KD, and the desired absolute difference between engine speed and turbine speed, L, adapted to repetitively calculate current instantaneous speed difference values |NE-NT|c, to store in memory and recall from memory previously calculated instantaneous speed difference values |NE-NT|p and previously calculated duty cycle values, DCp, and to repetitively calculate the current duty cycle, DCc, from the relationship
    
    
    space="preserve" listing-type="equation">DC.sub.c =DC.sub.p -KP(|NE-NT|.sub.c -L)-KD(|NE-NT|.sub.c -|NE-NT|.sub.p);

    andmeans for converting the binary value of the current duty cycle to an analog current that energizes the solenoid.

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