NEGATIVE PRESSURE SENSOR ABNORMALITY DETECTION DEVICE

摘要

PROBLEM TO BE SOLVED: To detect abnormality of a booster negative pressure sensor for detecting the pressure of a negative pressure chamber of the vacuum booster.

SOLUTION: A check valve is provided between an intake manifold and the negative pressure chamber of the booster. The check valve allows suction of air from the booster to the intake manifold, and inhibits the reverse. When an engine negative pressure PScomes close to the vacuum, a booster negative pressure PBalso concurrently comes close to the vacuum. Further, the booster does not have a function to bring the pressure of the negative pressure chamber close to the vacuum, and, therefore, the booster vacuum PBdoes not come closer to the vacuum than the engine negative pressure PS. In a state where the engine negative pressure PSis kept constant after being decreased, if the booster negative pressure PBcomes closer to the vacuum than an abnormality detection threshold PTHII, the booster negative pressure sensor is determined as being abnormal.

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