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Method and apparatus for automatic transmission cruise control

  • US 4,660,672 A
  • Filed: 10/15/1984
  • Issued: 04/28/1987
  • Est. Priority Date: 10/15/1983
  • Status: Expired due to Term
First Claim
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1. A method of automatically controlling the speed of an automotive vehicle having an engine and a transmission, at a preselected target value comprising the steps of:

  • actuating a vehicle speed control device to control an actuator operatively connected with a throttle valve of said engine in a manner to vary the opening degree of said throttle valve in place of a manually produced signal in a manner to maintain said preselected target speed;

    rendering a transmission control circuit which is discrete from said vehicle speed control device and which controls the shifting of said transmission between a plurality of forward speed ratios in accordance with a predetermined shift schedule, incapable of downshifting said transmission from a preselected gear ratio to the next lower one once said transmission control circuit has upshifted said transmission to said predetermined gear ratio irrespective of the changes in vehicle speed and engine load at all times when said speed control device is actuated;

    using said vehicle speed control device to induce a downshift from said predetermined gear ratio to the next lower one, if the load on said engine increases to a level whereat the vehicle speed falls a predetermined amount below said target level; and

    maintaining said downshift until a predetermined phenomenon occurs.

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