| 摘要 |
PURPOSE:To accurately detect blinding by comparing blinding limit differential pressure according to the intake air quantity obtained from the absolute pressure on the upstream side of an air cleaner with a difference in pressure between the upstream and downstream sides of the main cleaner, and detecting blinding from the comparison result to give a warning. CONSTITUTION:Pressure introducing pipes 7a, 7b are respectively extended from the upstream and downstream sides of an air cleaner 5 and connected to a pressure detecting portion 1. The pressure detecting portion 1 comprises a pressure sensitive rubber 2 as a differential pressure detector, the peripheral edge of which is clamped by the inner peripheral wall of a housing 11 and a pressure sensitive rubber 3 as an absolute pressure detector disposed in a circular recess portion 21 formed at the central portion of an end surface of the pressure sensitive rubber, that confronts with an upstream negative pressure chamber 13. Output signals of the pressuresensitive rubbers 2, 3 are input to a blinding detecting circuit 4, and on setting a blinding limit differential pressure according to the intake air quantity obtained from an absolute pressure detected value, the limit differential pressure and a detected differential pressure are compared. When the limit differential pressure N smaller then the detected differential pressure, the occurrence of blinding is decided to operate warning means 9. |
