| 摘要 |
<P>PROBLEM TO BE SOLVED: To diagnose failure, even when suction pipe pressure downstream of a throttle valve becomes positive pressure, when a supercharger operates. <P>SOLUTION: Purge passages 12 and 13 are respectively communicated with an air chamber 2 and the upstream side of the supercharger 5 of an intake passage 3, and a purge passage 11 for collecting both purge passages 12 and 13 is communicated with a canister 10. The canister 10 and a fuel tank 7 are communicated via an evaporation passage 9, and purge valves 14 and 15 are interposed in the respective purge passages 12 and 13. When a diagnostic condition is realized, the respective valves 14 and 15 are closed, and after holding internal pressure of an evaporation purge system reaching the fuel tank 7 from the respective valves 14 and 15, negative pressure is introduced from an air chamber 2 by opening the valve 14 when the suction pipe pressure Pa in the air chamber 2 is negative pressure, and the negative pressure is introduced from an upstream side intake passage 3 by opening the valve 15 in positive pressure. Afterwards, when tank internal pressure Pt reaches target negative pressure Pm, the existence of failure is diagnosed by detecting an internal pressure increase by evaporation fuel by closing both valves 14 and 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
