To provide a technique capable of more accurately detecting an angle of a camshaft in an internal combustion engine.
This cam angle detection device inputs an output signal of a sensor unit 1 to a low-pass filter 2 to remove noise, compares the output signal with a plurality of threshold values to input it to a comparator 3 outputting pulses, and detects the angle of the camshaft based on the number of the pulses generated from the comparator 3. The cam angle detection device is provided with a second comparator 4 having second threshold values of which number is smaller than that of the threshold values in the comparator 3. When rotational frequency is below reference one, the angle of the camshaft is detected based on the number of pulses output from the comparator 3 as a result of input of the output signal of the sensor unit 1 to the low-pass filter 2 and the comparator 3. When the rotational frequency is the reference one or larger, the angle of the camshaft is detected based on the number of pulses output from the second comparator 4 as a result of input of the output signal of the sensor unit 1 to the second comparator 4 without interposing the low-pass filter 2.
Mayuko Wakuda
Kazunobu Sera
Tsutomu Toyama
Takehiko Sekine
Koichiro Sakai
Fuminori Miyashita