Patent ID: 11933259
Assignee: YAMAHA HATSUDOKI KABUSHIKI KAISHA
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F  Y | IPC F

Claim 7:
8. A control method for controlling ignition timing of an internal combustion engine of a marine propulsion device, the control method comprising:
storing at least one of a first ignition timing map or a second ignition timing map, the first ignition timing map associated with a first fuel, and the second ignition timing map associated with a second fuel that is more likely to cause knocking of the internal combustion engine than the first fuel;
controlling the ignition timing of the internal combustion engine based on either the first ignition timing map or the second ignition timing map;
detecting a magnitude of the knocking of the internal combustion engine;
determining whether or not the knocking of the internal combustion engine has occurred in a range in which a rotational speed of the internal combustion engine is greater than or equal to a predetermined speed;
controlling the ignition timing of the internal combustion engine based on:
the first ignition timing map by executing timing retardation correction of the ignition timing based on the first ignition timing map when it is determined that the knocking of the internal combustion engine has occurred; or
the second ignition timing map by executing a timing advancement correction of the ignition timing based on the second ignition timing map when it is determined that the knocking of the internal combustion engine has not occurred; and

canceling the timing retardation correction or the timing advancement correction when the rotational speed of the internal combustion engine becomes lower than the range during execution of the timing retardation correction or the timing advancement correction.