Shift enable control method/system

  • US 5,272,939 A
  • Filed: 07/06/1992
  • Issued: 12/28/1993
  • Est. Priority Date: 07/06/1992
  • Status: Expired due to Term
First Claim
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1. A control method for controlling the at least partially automated implementation of selected shifts of a vehicular mechanical change gear transmission system comprising a controlled fuel throttle controlled engine (E) having a determined torque capacity, a multi-speed change gear mechanical transmission (10) having a plurality of known gear ratios, an input shaft (16) and an output shaft (90) adapted to drive vehicular drive wheels, a first sensor (98) for providing a first input signal indicative of transmission input shaft (16) rotational speed, a second sensor (100) for providing a second input signal indicative of vehicle speed, a third sensor (DL) for providing an input signal indicative of engine torque, means for differentiating said second signal with respect to time to determine a fourth signal indicative of current vehicle acceleration, and a transmission actuator (112, 70, 96) for controlling shifting of the transmission, said control method characterized by;

  • predetermining a minimum acceptable vehicle acceleration (AO) after an upshift,determining the desirability of an upshift from a currently engaged transmission ratio to a target transmission ratio,determining as a function of at least currently engaged gear ratio and said input signals indicative of (i) current engine torque and (ii) current vehicle acceleration, an expected required drivewheel torque (T0) to maintain a least said minimum vehicle acceleration (A0) under current vehicle operating conditions;

    determining as of function of (i) the expected required drivewheel torque (T0) to maintain at least said minimum vehicle acceleration (A0) under current vehicle operating conditions, (ii) the gear ratio of the selected target gear ratio and (iii) the expected maximum available torque to the drivewheels in the target transmission ratio (206), if said expected maximum available torque will at least equal said expected required drivewheel torque upon engagement of the target transmission ratio if the selected shift is implemented, andcausing the initiation of a selected shift only upon a determination of that said maximum available torque will at least equal said expected required drivewheel torque upon engagement of the target transmission ratio.

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