Patent ID: 7351184

Claim:
A system for controlling operation of an internal combustion engine connected to a machine through a variable speed reducer that reduces a speed of the engine to drive the machine, comprising: an actuator moving a throttle valve installed in an intake pipe of the engine; a crank angle sensor detecting the speed of the engine; an engine speed controller controlling operation of the actuator such that the detected engine speed becomes equal to a desired engine speed; a speed sensor detecting a speed of an output shaft of the variable speed reducer; a throttle position sensor detecting an opening of the throttle valve; an engine output estimator estimating an output of the engine based on the detected engine speed and the detected throttle opening; a desired engine speed changer changing the desired engine speed to a value in a speed-increasing direction when the estimated engine output is determined to be greater than a rising output threshold value; and a speed reduction ratio changer changing a speed reduction ratio of the variable speed reducer based on the detected engine speed such that the detected output shaft speed becomes equal to a desired output shaft speed.