| 摘要 |
PROBLEM TO BE SOLVED: To conduct atmospheric pressure detection even in medium or low load operational state of an internal combustion engine, and to reduce error between obtained atmospheric pressure and present atmospheric pressure. SOLUTION: Intake air pressure or atmospheric pressure is introduced into a back pressure chamber of a pressure control valve 30, resulting in generating differential pressure in fuel pressure on an fuel injection valve 5 based on difference between the intake air pressure and the atmospheric pressure. The differential pressure emerges as the change of a fuel injection amount from the fuel injection valve, and is calculated as an air-fuel ratio F/B(feed back) correction coefficient based on each output from an air-fuel ratio sensor 12. Thereby, the intake air pressure sensed by an intake air sensor 11, the air-fuel ratio F/B correction coefficient, and set pressure of the pressure control valve 30 are found, so that the atmospheric air pressure is calculated. Accordingly, the atmospheric air pressure of an internal combustion engine 1 is calculated not only in a conventional high load operational state but also in a medium or low operational state. Error between the atmospheric pressure obtained by atmospheric pressure detection processing and the present atmospheric pressure is reduced to improve reliability.
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