| 摘要 |
PROBLEM TO BE SOLVED: To provide a control device and control method for ignition timing, capable of suppressing occurrence of knocking even in a case where concentration of methane decreases.SOLUTION: A control device 50 controls ignition timing of an ignition plug at base ignition timing according to the operation state of an engine 5 and at target ignition timing based on a correction amount to the base ignition timing. The control device 50 calculates a suction air fuel ratio based on an air amount of air fuel mixture and a fuel amount of the air fuel mixture, and an exhaust air fuel ratio based on an oxygen concentration of exhaust gas. Then, the control device 50 delays the correction amount, when a ratio of the exhaust air fuel ratio and the suction air fuel ratio is a value different from an allowance, and the exhaust air fuel ratio is higher than the suction air fuel ratio.SELECTED DRAWING: Figure 1 |
