LPG小型点燃式发动机怠速工况下微粒排放特性研究

Characteristics of Particulate Emissions at Idle from a Small LPG EFI SI Engines

介绍了LPG点燃式发动机在怠速工况下的微粒排放特性,试验在一台电控单缸机上进行。通过在不同混合气过量空气系数下的试验,发现理论空燃比附近微粒的排放量最少;在混合气浓区的微粒排放随着过量空气系数变小而增多;在混合气稀区的微粒排放随过量空气系数增大也略有增加。微粒的排放随点火提前角的推迟有先减小后增加的趋势。随转速的增加,粒径峰值逐渐向粒径增大变化。怠速工况下的微粒粒径主要集中在(23．7～133)nm。颗粒物排放浓度与HC排放的浓度在趋势上有较好的一致性。

This paper presents the experimental results of Particulate Matter （PM） emissions at idle from a small single cylinder EFI SI engine fueled with LPG. The objective of this experiment is to briefly find out the characteristics of PM emissions at idle and to learn the effects of relative parameters on PM emissions , such as Lambda, spark advanced angle and idle speed. The distribution of particle size , PM superficial area and its volume are investigated. It is found that the magnitude of particle is mainly 105 and the dominating spectrum of the PM diameter is between （23.7 - 133） nm. At various Lambdas, the PM total number is the least under stoichiometric value. With the delay of spark ignition, the total number of PM emissions becomes lower firstly and in succession higher. The similar trend can be found when the idle speed is raised, which the low-water mark of total PM emission is around 1 600 r/min. Besides, it is also found that the trend of particulate matter emissions is similar with the HC emissions, which implies that some relationships exist between PM and HC emissions.