Carbon tank cleaning electromagnetic valve leakage monitoring method

Abstract

The invention relates to a carbon tank cleaning electromagnetic valve leakage monitoring method, and belongs to the technical field of engine fault diagnosis. The method comprises the following stepsthat after an engine is successfully started, an EVAP system closes a cleaning electromagnetic valve and a ventilation valve of an evaporation system, so that the evaporation system is in a closed state; a vacuum degree change value of the evaporation system is monitored in a set desorption flow integral threshold [delta]INT, and the vacuum degree change value of the evaporation system is converted into a real vehicle vacuum degree change curve; the EVAP system compares the real vehicle vacuum degree change curve with a calibration vacuum degree change curve to obtain an equivalent leakage aperture of the cleaning electromagnetic valve; and the EVAP system detects whether the equivalent leakage aperture is larger than a set value or not, if the equivalent leakage aperture is larger than the set value, an OBD system judges that leakage exists in the cleaning electromagnetic valve, and overhaul prompting is conducted on the cleaning electromagnetic valve. The monitoring method can accurately monitor whether leakage exists in the cleaning electromagnetic valve or not, and the troubleshooting difficulty of the OBD system is lowered.

Description

technical field [0001] The present application relates to the technical field of engine fault diagnosis, in particular to a method for monitoring the leakage of a carbon canister cleaning solenoid valve. Background technique [0002] Light vehicle pollutant emission limits and measurement methods require the on-board diagnostic system (OBD) to monitor the small leakage of the evaporation system, but there is no clear requirement to monitor the leakage of the canister cleaning solenoid valve, the main reason is that even if the cleaning solenoid valve leaks Or if it is not closed tightly, the oil and gas from the carbon tank will generally be drawn into the cylinder for combustion through the negative pressure suction of the intake manifold, and will not leak into the atmosphere and cause pollution to the environment. [0003] But in fact, the leakage of oil and gas into the cylinder through the carbon tank cleaning solenoid valve will first of all have an impact on the norma...

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Problems solved by technology

[0008] The embodiment of the present application provides a method for monitoring the leakage of the carbon tank cleaning solenoid valve to solve the problems of inaccurate determination of the leakage aperture of the evaporation system and high detection cost in the related art

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