Analysis of ion current signal during negative valve overlap of HCCI combustion with high compression ratio
Analysis of ion current signal during negative valve overlap of HCCI combustion with high compression ratio
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DOI：
10.1177/1468087420972899
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发表时间：
2020-11
影响因子：
2.5
通讯作者：
Maximilian Wick;Denghao Zhu;J. Deng;Liguang Li;J. Andert
中科院分区：
文献类型：
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作者：
Maximilian Wick;Denghao Zhu;J. Deng;Liguang Li;J. Andert
均质压燃（HCCI）燃烧是一种高燃烧效率和超低NOx排放的低温燃烧过程。缸内压力的急剧增加和在操作范围的极限处的不稳定燃烧序列会损坏发动机并且将HCCI的使用限制到部分负载操作。这可以使用基于燃烧参数如指示平均有效压力和燃烧相位的闭环燃烧控制来完成。由于缸内压力传感器是昂贵的部件，因此不适合串联应用，离子电流传感器可以用作关于燃烧的信息的附加源。使用与基于压力的测量中使用的方法类似的方法的燃烧分析可以使用离子电流信号的在线分析来实现。在这项研究中，离子电流传感器将检查其适用于燃烧控制下的HCCI条件下，稀空燃比和高压缩比。研究发现，离子电流信号强烈依赖于边界条件。特别是空燃比对燃烧过程中信号强度的影响非常大。当结合燃料预喷射使用具有负气门重叠的气门正时时，除了燃烧期间的离子电流信号的峰值之外，还可以发现接近气体交换上止点的离子电流信号的另一个峰值。同时，在NVO过程中，很难从气缸压力信号中提取信息。在稀燃条件下，该峰值甚至超过燃烧期间的信号。这项研究分析了离子电流信号在NVO和它的潜力，用于未来的燃烧控制概念。离子电流信号显示了在高负荷下稳定HCCI燃烧的潜力。然而，后期燃烧循环的预测仍然具有挑战性。
Homogenous charge compression ignition (HCCI) combustion is a low temperature combustion process which combines high combustion efficiency with ultra-low N O x raw emissions. Steep increases of the in-cylinder pressure and unstable combustion sequences at the limits of the operating range can damage the engine and limit the use of HCCI to part load operation. This can be done using closed loop combustion control based on combustion parameters like the indicated mean effective pressure and the combustion phasing. Since in-cylinder pressure sensors are expensive components and therefore not suitable for series application, ion current sensors can be used as an additional source of information about the combustion. Combustion analysis using methods similar to those used in pressure based measurements can be implemented using an online analysis of the ion current signal. In this study, the ion current sensor will be examined for its suitability for combustion control under HCCI conditions with lean air/fuel ratios and high compression ratios. Research has found that the ion current signal is strongly depended on the boundary conditions. Especially the air/fuel ratio which plays an important role for signal strength during the combustion process. When using valve timings with negative valve overlap in combination with a fuel pre-injection, a further peak of the ion current signal close to the gas exchange top dead center can be found in addition to the one during combustion. At the same time, it is hard to extract information from the cylinder pressure signal during NVO. Under lean conditions this peak even exceeds the signal during combustion. This study analyzes the ion current signal during NVO and its potential to be used for future combustion control concepts. The ion current signal shows potential to stabilize HCCI combustion at high loads. However, the prediction of late combustion cycles is still challenging.