Device and method for controlling misfire of spark ignition engine

Abstract

The invention discloses a device for controlling the misfire of a spark ignition engine. The device comprises an ignition coil, a spark plug, an ionic current detection unit, a signal processing unit, a micro control unit and an ignition driving unit, wherein the ignition coil is used for providing an ignition power source to the spark plug; the spark plug is used for igniting in an air cylinder;the ionic current detection unit is used for detecting the ionic current of the ignition coil and sending the ionic current to the micro control unit; the signal processing unit is used for receivingan engine working state signal, processing the engine working state signal and then sending the processed engine working state signal to the micro control unit; the micro control unit is used for judging whether misfire happens or not according to the received ionic current and the engine working state signal; and the ignition driving unit is used for driving the ignition coil and controlling thespark plug to ignite if misfire exists. The invention also discloses a method for controlling the misfire of the spark ignition engine. According to the invention, the damage caused by misfire is minimized through misfire control.

Description

technical field [0001] The invention relates to engine control technology, in particular to a method and device for detecting and controlling combustion in a spark ignition engine cylinder. Background technique [0002] According to the definition of California Air Resources Board (CARB) regulations, engine misfire refers to the phenomenon of no combustion or poor combustion in the cylinder due to insufficient ignition energy, too lean or too rich mixture, poor compression or other reasons. [0003] When misfire occurs, the average indicated pressure of the combustion process is greatly reduced, and the performance of the engine deteriorates. [0004] Studies have shown that a misfire rate of about 2% will cause harmful emissions to exceed the emission standard limit by 1.5 times. [0005] What's more serious is that the unburned mixture will burn after reaching the catalyst, which will easily cause damage to the catalyst. [0006] In order to avoid the above-mentioned haz...

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Problems solved by technology

[0008] However, this method is prone to misdiagnosis when the road conditions are bad, and requires an additional gravity acceleration sensor. In addition, this method can only be used within a certain range of engine operating conditions, especially at high speeds with small loads.

[0009] The most reliable way to judge misfire is to use the in-cylinder pressure sensor, but the price of the in-cylinder pressure sensor is extremely high, and it has strict requirements for installation and has a short service life

[0010] Oxygen sensors and exhaust pressure sensors can also be used to detect misfires, but they also have some disadvantages, such as high device costs, sluggish response, and inability to judge which cylinder is misfired

[0011] The existing technology only involves the method of detecting misfire, but does not mention what kind of real-time compensatory measures can be taken to prevent the damage caused by misfire in a timely and effective manner after misfire is detected

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