To easily and finely adjust speed of a vessel by calculating and controlling the opening of a secondary air valve according to reference engine speed based on the temperature of an engine and target engine speed calculated by a correction signal showing a correction value according to a manual operation.
Reference engine speed is determined from a detected engine temperature (S22), whether an engine is in a non-load idle state or not is judged (S23), and when the engine is not in the non-load idle state, a correction voltage signal is detected (S24). Next, a correction value of engine speed is calculated according to this correction voltage signal (S25) and target engine speed to which the reference engine speed and the correction value of the engine speed are added is calculated (S26). Next, the opening of a secondary air valve is determined from the present engine speed detected from a reference location signal and the target engine speed (S28) and the actual opening of the secondary air valve is controlled so as to be made to coincide with this opening (S29).
KUWAHARA SHIGEAKI
SHIDARA SADAFUMI
HONDA MOTOR CO LTD
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