Ionic current based spark ignition engine preignition detection control device

Abstract

The invention discloses an ionic current based spark ignition engine preignition detection control device. Before an ionic current detection device detects spark ignition, autoignition happens in a combustion chamber, an ethanol solenoid valve is controlled in the compression stroke to be turned on to inject a certain amount of ethanol so as to lower the temperature in the combustion chamber and restrain preignition, and the ethanol solenoid valve and a gasoline solenoid valve are controlled to be turned on simultaneously according to gasoline injection pulse width in subsequent circulation, so that the ethanol is mixed in gasoline, and preignition tendency in the subsequent combustion circulation is reduced; if preignition happens continuously, the ethanol is injected in the compression stroke, if preignition does not happen in the subsequent circulation, ethanol injection amount in fuel is decreased along with circulation, and finally pure-gasoline injection is restored. The ionic current based spark ignition engine preignition detection control device has the advantages that when one cylinder is detected to be pre-ignited, fuels such as the ethanol with high latent heat of vaporization are injected into the cylinder so as to cool compressed mixed gas, the temperature in the combustion chamber at upper dead point of compression is lowered, non-combusted mixed gas is restrained from autoignition, super detonation caused by preignition is prevented, and damage to an engine is reduced.

Description

technical field [0001] The invention belongs to the technical field of internal combustion engines, in particular to an ion current-based spark ignition engine pre-ignition detection and control device. Background technique [0002] In recent years, the development of high-pressure small-displacement gasoline engines has focused on knock control. By optimizing the cooling cycle, ignition timing, fuel injection strategy, continuous valve variable technology, compact combustion chamber design and higher intake pressure, etc. , so that the engine brake mean effective pressure (BMEP) is expected to reach 2.5MPa. However, as the engine load continues to increase, a sporadic and uncontrollable pre-ignition phenomenon appears at low speed and high load. Pre-ignition is sporadic and discontinuous, which makes it difficult for engine manufacturers to detect and control it effectively. In addition, pre-ignition tends to produce extremely high combustion pressure, which can exceed 20M...

AI Technical Summary

Problems solved by technology

However, as the engine load continues to increase, a sporadic and uncontrollable pre-ignition phenomenon occurs at low speed and high load

Pre-ignition is sporadic and discontinuous, which makes it difficult for engine manufacturers to detect and control it effectively. In addition, pre-ignition tends to produce extremely high combustion pressure, which can exceed 20Mpa, resulting in great shock, vibration and noise, which can damage the engine. No effective means of inhibiting premature combustion has yet been found

In the existing research, Toyota Motor Co., Ltd. in "Knock Determination Device and Knock Determination Method for Internal Combustion Engines" compares the correlation coefficient for knock determination with the preset knock determination threshold, and corrects it according to the comparison result. The knock judgment threshold used in the knock judgment of each combustion improves the accuracy and reliability of knock judgment, but it cannot be applied to the pre-ignition detection of supercharged engines

Mazda Motor Co., Ltd. applied the rich air-fuel ratio to suppress pre-ignition in the "control method and control device for spark ignition engines". However, because it did not use ion current detection, the accuracy was poor. The detection can detect the pre-ignition signal in time and accurately, and at the same time, the fuel with high vaporization latent heat is injected to reduce the temperature in the combustion chamber and effectively suppress the pre-ignition

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