汽油机直喷起动建模与分析

Modeling and Analysis of Engine Direct Injection Start

为了解决汽油机直喷起动过程中缸压、放热率等重要参数难以通过发动机试验获得的问题,建立详尽的发动机动力学模型描述膨胀缸喷油点火后的过程,并通过试验标定验证了模型的准确性。利用该模型对直喷汽油机的起动过程进行了分析,结果表明,起动的最有利初始位置是压缩上止点后100°~130°,对起动过程影响程度从高到低的因素依次是摩擦、压缩缸压缩气体损失、传热、漏气,而泵气损失可忽略不计。

Some key parameters in the starting process of GDI engine, including cylinder pressure, heat release rate are difficult to obtain in engine test. To solve this problem, an exhaustive engine dynamic model is established to describe the process after fuel injection and ignition of the expansion cylinder, and accuracy of the model is verified with calibration. The starting process is analyzed with this model. The results show that the best initial position of starting is 100°~130° after the compression TDC, the factors affecting the starting process from high to low level are friction, compression gas loss of the compression cylinder, heat transfer and gas leakage respectively, with pumping loss negligible.