Throttle control for internal combustion engine having failure detection function

A throttle control apparatus for an internal combustion engine comprising:

• an accelerator position sensor for detecting an accelerator position of an accelerator pedal;
• a throttle angle sensor for detecting an actual opening of a throttle valve as an actual throttle angle;
• control variable calculation means for calculating a control variable for making the actual throttle angle detected by the throttle angle sensor match a target throttle angle on the basis of a deviation between the actual throttle angle and the target throttle angle which is a target opening of the throttle valve set in accordance with the accelerator position detected by the accelerator position sensor;
• throttle control means for controlling the actual throttle angle by driving an actuator in accordance with the control variable calculated by the control variable calculation means;
• failure detection means for detecting a failure in a throttle control;
• fail-safe means for restraining an upper limit of the target throttle angle to a value smaller than a predetermined value in the event of at least a failure detected in the throttle control;
• reduced cylinder count control means for executing reduced cylinder count control by setting a reduced cylinder count indicating the number of operating cylinders of the internal combustion engine after processing carried out by the fail-safe means;
• and
• reduced cylinder count limitation means for setting a lower limit of the reduced cylinder count set by the reduced cylinder count control means in order to limit the number of operating cylinders.