Diagnosis method of high pressure fuel tank leakage

Abstract

The invention relates to the field of vehicle performance test, and specifically relates to a high pressure resistant fuel tank leakage diagnosis method. The high pressure resistant fuel tank leakage diagnosis method is characterized in that the high pressure resistant fuel tank leakage diagnosis method determines the pressure actual measurement value of a fuel tank pressure sensor; when the pressure is too high, an enclosed diagnosis mode is used, or an opening diagnosis mode is used; the enclosed and opening diagnosis mode includes opening an air pump to perform internal cycle inflation to obtain a reference steady current, opening the air pump to inflate a high pressure resistant fuel tank to obtain an actual measurement steady current, and comparing and determining whether leakage exists in the high pressure resistant fuel tank; and the enclosed and opening diagnosis method is characterized by using the fuel tank pressure sensor to record a fuel tank pressure-time curve and determining whether leakage exists in the high pressure resistant fuel tank according to the pressure change rate. The high pressure resistant fuel tank leakage diagnosis method selects the most suitable diagnosis method according to the practical pressure state, thus greatly reducing discharging of fuel vapor during the diagnosis process, reducing pollution, and satisfying the requirement for evaporative discharge and discharging during the oiling process.

Description

technical field [0001] The invention relates to the field of vehicle performance testing, in particular to a method for diagnosing leakage of a high-pressure fuel tank. Background technique [0002] With the upgrading of emission regulations from China V to China VI, the technical requirements for the evaporation system are increasing, and the requirements are mainly as follows: [0003] 1) Added fuel system leak diagnosis [0004] 2) Tightened evaporative emission requirements [0005] 3) Add emission requirements for refueling process [0006] Currently, on traditional gasoline engine vehicles, for technical requirement 1), a diagnostic air pump can be used to inflate the fuel system (fuel tank, carbon canister) to determine whether there is leakage in the fuel system, especially the fuel tank. [0007] However, as fuel consumption requirements are getting higher and higher, traditional gasoline engines are gradually unable to meet fuel consumption requirements, so hybr...

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Problems solved by technology

[0008] Due to the existence of the high-pressure resistant fuel tank and the fuel tank isolation valve, when the fuel tank isolation valve is closed, the air pump originally used to test the fuel system leakage cannot directly inflate the fuel tank, but for the purpose of diagnosing fuel tank leakage, it is opened rashly when the fuel tank is still under high pressure If the fuel tank isolation valve releases the fuel tank pressure and then uses the air pump for diagnosis, it is very likely that too much fuel vapor will be discharged into the atmosphere during the pressure relief process, which will cause certain pollution to the environment and cannot meet the requirements for evaporative emissions and emissions during refueling

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