高性能低排放小型非道路柴油机的开发

以某小型非道路单缸直喷式柴油机为研究对象,综合运用CAE与CFD优化设计技术,从燃烧系统多参数优化匹配与机械系统改进设计2个方面入手,进行高性能低排放小型非道路柴油机开发。利用Hydism与Fire等多维模拟软件,对燃油供给系统参数、燃烧室与进气涡流参数进行虚拟协同优化,分析三者对燃烧过程与排放性能的影响,并确定了优化方案;同时利用有限元分析软件,对机体、缸盖及活塞等机械系统进行改进设计,提高整机的刚度强度及可靠性,有效降低机油耗。试验结果表明:最终优化方案与原机相比,燃油经济性与排放性能得到有效改善,CO、HC+NOx、PM排放分别减少了49%、58%、74%,燃油耗降低了6.9%,机油耗降低了59%,可满足EPA非道路柴油机第Ⅳ阶段法规限值,为高性能小型非道路柴油机开发提供了参考。

Development of small off-road diesel with high-performance and low emission

In order to develop small non-road diesel engines with high-performance and low emission as well,a small non-road direct injection type diesel engine with a single cylinder was taken as the research object.The CAE and CFD comprehensively applied,and the research was proceed with two approaches which were the optimization matching of combustion system parameters and the improvement design of mechanical system.Optimization matching of fuel injection system parameters,combustion chamber and intake swirl ratio were studied by using the multi-dimensional simulation software such as Hydism,Fire and so on.The optimization plan was determined after the effects on combustion process and emission performance were analyzed.The ameliorated design was applied to cylinder block,cylinder head as well as piston,etc.In addition,the finite element analysis software was used.As a consequence,the structural intensity,stiffness and dependability of the diesel engine were enhanced.At the same time,the machine oil consumption reduced effectively.The results of the test showed that,compared with the original engine,the fuel economy and the emission performance were improved effectively.The quantity of CO,HC + NOx and PM reduced by 49%,58%,74% respectively,while fuel oil and machine oil consumption reduced by 6.9% and 59%.The emission performance of the optimized scheme was obviously improved which could meet EPA Ⅳ Non-road Diesel Engine Emission Limit well.This paper provides a reference for the development of small high-performance non-road diesel engines.