Control apparatus for internal combustion engine

1. A control apparatus for an internal combustion engine, wherein a first crank angle sensor and a second crank angle sensor are disposed for detecting rotation of a crankshaft; the second crank angle sensor is arranged so as to have a predetermined output phase difference relative to the first crank angle sensor; the first and second crank angle sensors output pulse signals which have rising edges and falling edges that are respectively formed upon appearances and disappearances of a plurality of teeth to-be-detected arranged at a circumference of a crank plate; combinations of the rising edge and the falling edge detected by the first crank angle sensor, with output values of the second crank angle sensor are respectively set as a first output pattern and a second output pattern, while combinations of the rising edge and the falling edge detected by the second crank angle sensor, with output values of the first crank angle sensor are respectively set as a third output pattern and a fourth output pattern; and engine-rotation-direction detection means is disposed for deciding that a rotation direction of the engine has changed, when the output patterns have changed; comprising:

crank angle calculation means for calculating a crank angle between the edges which are detected by the first crank angle sensor and the second crank angle sensor, on the basis of a crank cycle between the edges; and

engine-rotation-direction detection inhibit means for inhibiting detection of the engine rotation direction on the basis of the crank angle calculated by said crank angle calculation means, wherein said engine-rotation-direction detection inhibit means inhibits the detection of the engine rotation direction based on the output patterns, in a case where the crank angle calculated by said crank angle calculation means has satisfied a predetermined inhibit decision condition.

2. A control apparatus for an internal combustion engine as defined in claim 1 , wherein said engine-rotation-direction detection inhibit means does not use the output pattern based on the edges forming the crank angle, for the detection of the engine rotation direction, in the case where the crank angle calculated by said crank angle calculation means has satisfied the predetermined inhibit decision condition.

3. A control apparatus for an internal combustion engine as defined in claim 1 , wherein said crank angle calculation means calculates the crank angle by using the cycle between the edges as has a smaller detection error measured by either of the crank angle sensors.

4. A control apparatus for an internal combustion engine as defined in claim 1 , wherein the inhibit decision condition is set on the basis of error ranges which can be assumed when the edges are detected by the first crank angle sensor and the second crank angle sensor.

5. A control apparatus for an internal combustion engine as defined in claim 1 , wherein said crank angle calculation means executes the calculation of the crank angle when it has been decided that the engine is stably rotating in one direction.

6. A control apparatus for an internal combustion engine as defined in claim 1 , further comprising means for inhibiting controls which are performed on the basis of the engine rotation direction, and for reporting the inhibit of the detection of the engine rotation direction to a driver of a vehicle on which the engine is carried, when the detection of the engine rotation direction is inhibited by said engine-rotation-direction detection inhibit means.