Method and device for leak diagnosis of fuel evaporative emission system
A technology of evaporative emission and diagnosis method, applied in the field of vehicles, can solve the problems of inability to diagnose leakage, inability to meet the leakage diagnosis of fuel evaporative emission system, etc., and achieve the effect of accurate diagnosis
Active Publication Date: 2021-12-07
BYD CO LTD
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Problems solved by technology
[0002] In the prior art, there are control programs and failure diagnosis programs for the high-pressure fuel tank system of PHEV models during the refueling process, but there is no mention of the program control for OBD II fuel evaporation system leakage diagnosis, and the leakage cannot be diagnosed, which cannot meet the requirements of the National VI regulations. Requirements for Leak Diagnosis of Fuel Evaporative Emission System
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[0053] As an embodiment, when the engine state of the vehicle acquired in the non-driven state, acquiring the fuel tank pressure values, comprising:
[0054] State of the vehicle when the engine is in the off state, acquiring the intake air temperature and water temperature of the vehicle;
[0055] When the vehicle is water and the temperature of the intake air temperature difference is less than a predetermined temperature, the fuel tank pressure values acquired.
[0056] Wherein the vehicle is determined in order to confirm the state of the vehicle is mainly a period of time after the turn off, collected by ECU temperature sensor and intake air temperature sensor, and comparison and determination, if the two temperatures are very similar, indicating that the vehicle is already in the flame a period of time, may be the next step.
[0057] The following embodiments specifically described by specific examples of the present application:
[0058] The present application is directe...
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This application proposes a leak diagnosis method and device for a fuel evaporative emission system. The leak diagnosis method includes: when the state of the internal combustion engine of the vehicle is in a non-driving state, obtain the fuel tank pressure value, and use the first fuel tank pressure value according to the fuel tank pressure value. The control strategy or the second control strategy diagnoses the leakage of the fuel evaporative emission system, wherein the first control strategy is to diagnose the leakage of the fuel evaporative emission system, and the second control strategy is to diagnose the leakage of both sides of the fuel tank isolation valve. The technical solution of the present application obtains the pressure value of the fuel tank and adopts different strategies to diagnose the leakage of the fuel evaporative emission system according to the fuel tank pressure value, thereby realizing the accurate diagnosis of the leakage of the fuel evaporative emission system.
Description
Technical field [0001] The present application relates to the technical field of vehicle, in particular, to a leak diagnosis method and apparatus for fuel evaporation emission systems. Background technique [0002] In the prior art, there is a control program and failure diagnostic procedure in the refueling process, but the procedure control of the leak diagnosis of OBDII fuel evaporation system is not mentioned. Cannot diagnose leaks, and cannot meet the national six regulations Requirements for leakage diagnosis of fuel evaporation emission systems. Inventive content [0003] The purpose of this application is to provide a leak diagnosis method and apparatus for fuel evaporation emission systems, which can achieve leakage diagnosis of fuel evaporation emissions systems. [0004] This application is achieved, and the first aspect of the present application provides a leak diagnosis method of a fuel evaporation emission system, and the fuel evaporation emission system includes ...
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IPC IPC(8): F02M25/08F02B77/08
CPCF02B77/083F02M25/0809
Inventor 王珂苏清炎
Owner BYD CO LTD