Engine catching fire determining device and method

Abstract

The invention discloses an engine misfire judging device and a misfire judging method. A cylinder pressure sensor collects a cylinder pressure signal in real time, an electronic control unit calculates the peak pressure in the cycle cylinder according to the pressure signal, and compares the peak pressure with the preset engine normal pressure. The pressure threshold value in the cylinder is compared during ignition and combustion. When the detected real-time peak cylinder pressure value is less than the threshold value, it is determined that the engine is misfired, and the oil level sensor is used to collect the fuel level signal of the fuel tank in real time to shield the diagnosis of low oil level misfire. The invention can judge the misfire under the stable working condition of the engine, and the procedure of misfire judgment is simplified, easy to realize and low in cost. Because it is a real-time detection of engine combustion conditions, it can accurately determine transient operating conditions such as acceleration and deceleration and misfires when driving on bumpy roads, and the accuracy of misfire judgments is greatly improved. Combined with the real-time detection of the oil level, it shields the low oil level misfire diagnosis, avoids the misfire diagnosis caused by the engine not igniting and burning due to lack of oil, and improves the accuracy of the misfire diagnosis.

Description

【Technical field】 [0001] The invention relates to a device and method for judging engine misfire. 【Background technique】 [0002] When the gasoline engine is running, due to no ignition, too rich or too lean mixture, low compression pressure or other reasons, the mixture sucked into the cylinder cannot be combusted, which is called misfire. When the engine misfire is serious, it will not only damage the three-way catalytic converter, but also cause exhaust gas emissions to be higher than normal standards, polluting the environment. Research has been carried out at home and abroad. Japanese Unexamined Patent Publication No. 04-171249 and Japanese Unexamined Publication No. 58-051243 each disclose a misfire device, which judges whether there is a misfire by calculating the data of the engine speed. [0003] In Chinese patent applications CN200410037513.6 and CN200410037512.1, a method for judging whether a misfire has occurred is disclosed based on the comparison between the ...

AI Technical Summary

Problems solved by technology

Although the influence of engine speed changes due to non-misfire factors such as flywheel looseness or clutch wear is eliminated, the engine is not working smoothly, and the engine speed is also unstable when the car is in transient conditions such as acceleration and deceleration or driving on bumpy roads. At this time, it is impossible to accurately determine whether the change in engine speed is caused by misfire or the change in engine speed caused by special working conditions. Therefore, an acceleration sensor will be used to judge bumpy roads, and the misfire diagnosis will be shielded when necessary. , which has certain defects, and the misfire at this time cannot be diagnosed

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