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Engine variable transmission control system

  • US 5,406,483 A
  • Filed: 03/22/1994
  • Issued: 04/11/1995
  • Est. Priority Date: 05/15/1991
  • Status: Expired due to Fees
First Claim
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1. An electronic control system for a self-propelled off-road vehicle having an internal combustion engine and a powershift transmission with a plurality of forward gears, said control system being for controlling powershift transmission and providing at least one control signal to said engine for specifying a speed at which said engine of said vehicle is to operate, said control system comprising:

  • mode selection means for allowing an operator of said vehicle to select a desired one of a plurality of operating modes including a maximum fuel economy mode, a comfort mode and a maximum horsepower mode;

    speed selection means for allowing said operator to select a desired vehicle ground speed;

    first electronic controller means responsive to said mode selection means and said speed selection means and operable under stored program control for providing transmission control signals that specify in which specific one of said plurality of forward gears said powershift transmission is to operate in accordance with said selected operating mode; and

    second electronic controller means operable under stored program control for providing at least one engine control signal required to command said engine to operate at one of a plurality of different engine speeds within a predetermined range in accordance with said desired vehicle ground speed,said first electronic controller means including first electrical output means for commanding said powershift transmission to operate in a controller selected one of said plurality of forward gears in response to said gear as specified by the current transmission control signals, and communications means for sending and receiving digital signals to and from said second electronic controller means,said second electronic controller means including second electrical output means for commanding said engine to operate at a particular one of said plurality of engine speeds indicated by said engine control signal, and communications means for sending and receiving digital signals to and from said first electronic controller means; and

    when in said maximum fuel economy mode said electronic control system selects particular ones of said plurality of forward gears and particular ones of said engine speeds to minimize fuel consumption of said engine, said electronic control system further allowing said engine speed to vary slightly to help achieve minimum fuel consumption while attempting to maintain an operator selected vehicle ground speed;

    when in said comfort mode said electronic control system selects particular ones of said plurality of forward gears and particular ones of said plurality of engine speeds to maintain an actual vehicle ground speed approximately equal to said operator selected vehicle ground speed while simultaneously reducing the number of shifts of said powershift transmission by varying said engine speed as necessary to compensate for changing loads experienced by said vehicle; and

    when in said maximum horsepower mode said electronic control means selects various ones of said plurality of gears and varies said engine speed in an attempt to maintain said operator selected vehicle ground speed approximately equal to said actual vehicle ground speed while simultaneously maintaining said engine operating at one of said plurality of engine speeds that produces a maximum horsepower at said operator selected vehicle ground speed.

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