CONTROLLING APPARATUS FOR INTERNAL COMBUSTION ENGINE

PURPOSE:To make it possible to control an internal combustion engine by outputting the crank-angle timing signal based on the first and third signals in place of the crank-angle timing signal, which is formed based on the first and second signals, when the second signal is abnormal. CONSTITUTION:With respect to the crank-angle timing signal based on the first and second signals, the coefficient of the second signal is started with the first signal as a reference. When the counted value at the intended timing is reached, the timing signal is outputted. This timing angle is temporarily made to be AA. The input time interval of the first signal is used for computation of the number of rotations of an engine and the like. The time interval of the measured crank angle 180 deg. is made to be TC. When the second signal is abnormal, the coefficient of the third signal is started with the first signal as a reference by the computation of TA=(AA/180 deg.)XTC. When the counted value at the intended timing TA is reached, the timing signal corresponding to the timing angle AA is outputted, and the internal combustion engine can be controlled. For example, the timings of the valve opening of an injector 8 and the ignition of an ignition coil 13 are formed based on the reference crank angle signal of a sensor 4 and the crank angle signal of a sensor 30. When the crank angle signal of the sensor 30 is abnormal, the signal is changed to the signal of the sensor 30 so as to use the third signal, and the timing signal is formed.