PURPOSE: To ensure the safety during driving of a car by intercepting a control operation attributed to an automatic stop/restart function during an appropriate period if a sensor detects unreasonable variation in car speed during the drive.
CONSTITUTION: An automatic engine stop/restart function ERS of a control circuit 1 is executed in such a manner that if a car is stopped due to some reasons, a traffic signal, for example, the engine is automatically stopped under a certain condition and then restarted by the normal starting operation. If a car speed V is temporarily changed to an unreasonable speed on account of a defect of a car speed sensor 12 during constant speed driving with the ERS operative, an ERS control command is outputted into I/O while an engine stop signal 44 and a starting signal 46 are not generated during an interval from a point after a lapse of a certain period from the variation to a point at which the car speed is returned to a damanded value. Since the malfunction of ERS attributed to the defective car speed sensor is prevented during driving of the vehicle, the safety may be ensured.
NOBA MASAHIKO
HORI SHINICHI
ONO MAKOTO
NIPPON DENSO CO