| 摘要 |
PROBLEM TO BE SOLVED: To improve durability and use a sensor system in common by rotary- driving a control shaft by an actuator, and varying the rocking fulcrum of a rocker arm to change the lift characteristic of an engine valve. SOLUTION: A counter reset to zero when a reference signal REF is generated is counted up for every position signal POS. The value of the counter when the first detection signal from a rocking position sensor is generated is taken as a value corresponding to the phase difference D1, and the value of the counter when the second detection signal from the rocking position sensor is taken as a value corresponding to the phase difference D2. An operating angle is detected from a difference (D2-D1) between the phase differences D1 and D2, and according to the detected operating angle and the phase difference D1 (or phase difference D2), the rotational phase of a cam shaft to a crankshaft is detected. Accordingly, the number of sensor is decreased so as to reduce the cost, and since the operating angle is detected by a non-contact sensor, high durability can be obtained.
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