外置废气再循环在增压发动机上的应用研究

A Study on the Application of External EGR on Turbocharged Engines

以一台1.5L涡轮增压发动机为研究对象,通过外部废气再循环(EGR)装置,将排气管内的废气引入进气歧管,在发动机台架上进行了各转速下的不同EGR率试验。探索研究了EGR对增压机的燃烧、动力性和经济性的影响及其对早燃的抑制作用。结果表明:在增压发动机中加入EGR后,由于废气的稀释和热容作用,使缸内燃烧持续期增大,排气温度下降,改变燃烧相位。这些影响使得油耗减少,一氧化碳(CO)和氮氧化物(NOx)排放也明显减少,也可以在一定程度上抑制早燃的发生。

Based on an in-line four cylinder 1.5L turbochargers engine, which is equipped with external exhaust gas recirculation (EGR) device, the EGR ratio tests were carried out on engine dynameters. The effects of different EGR ratio on combustion, dynamic performance, economic performance, as well as the restrain to low-speed pre-ignition(SPI) of turbocharged engine are researched. Results show that,the introduction of EGR into combustion could increase burning period, lower exhaust temperature, and change burning phase position by dilution effect and thermal capacity effect. These factors caused the significant decrease of the specific fuel consumption, carbon monoxide (CO) and nitric oxide (NOx) emissions. In addition, the SPI was suppressed in some degree.