Caterpillar Inc.

Navistar International Corporation

Robert T Schaar

Edward E Londt

Michael E Moncelle

A method of operating a vehicle engine equipped with a cruise control includes the step of operating the engine in accordance with fuel delivery limits within a first range of delivery limits when the speed of the vehicle is less than a first speed limit and the cruise control is engaged such that the engine is controlled to permit acceleration of the vehicle under substantially all operating conditions. The engine is operated in accordance with fuel delivery limits within a second range of delivery limits less than the first range of delivery limits when the speed of the vehicle is greater than the first speed limit but less than a second speed limit. The engine is operated in accordance with fuel delivery limits within a third range of delivery limits less than the second range of delivery limits when the speed of the vehicle is greater than the second speed limit whereby the engine is controlled to permit acceleration of the vehicle under less than substantially all operating conditions thereof. Such a method allows an operator of the vehicle to accelerate when traveling downhill beyond the second speed limit so that sufficient momentum can be gained to crest an upcoming hill.

Method of operating a vehicle engine

A control for and method of operating a vehicle engine (12) equipped with a cruise control (44) includes apparatus for and the steps of providing a memory (86) having stored therein first and second sets of data which control the position of a fuel rack (20) as a function of engine speed, determining when the cruise control (44) is engaged, retrieving the first set of data from the memory (86) when the cruise control (44) is engaged, retrieving the second set of data from the memory (86) when the cruise control (44) is not engaged and using the retrieved set of data to control the rate of fuel delivery to the engine (12) whereby extra power is available when the cruise control (44) is engaged to minimize downshifting. Also, fuel economy is improved and the set cruise control speed is better maintained.

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Chillicothe, IL, United States of America

Robert T Schaar