实现小型二冲程汽油机分层扫气的膜片式喷射化油器.doc

　内燃机学报　TRANSACTIONS OF CSICE?1999年 第17卷 第2期 vol.17 No2. 1999?--------------------------------------------------------------------------------?实现小型二冲程汽油机分层扫气的膜片式喷射化油器　　　　　 杨笑风　曾科　李国伟　蒋德明?摘要　发明并研究了一种结构简单的膜片式喷射化油器(DIC)，其工作原理是利用曲轴箱峰值压力给燃油加压，由一组膜片机构将进气喉口处的压差转换到燃油主量孔两侧，使供油量与进气量成正比，从而实现燃油的计量和喷射。　　 本系统和适当的扫气系统结合起来，可实现小型二冲程汽油机的分层扫气，减少燃油的短路损失，大幅度降低油耗和未燃碳氢排放。本文还提出了保留常规化油器的低负荷供油系统，用来解决一般简单喷射系统低负荷性能恶化的问题，又使燃油系统结构大为简化。　　本文描述了DIC的基本概念和工作原理，并在30 cm3试验专用汽油机上进行了膜片式喷射化油器供油特性和发动机性能的对比试验。关键词　二冲程汽油机；化油器；分层扫气An Investigation on Diaphragm Injection Carburetor in a Two Stroke Spark Ignition Engine with Stratified ScavengingYang Xiaofeng　Zeng Ke　Li Guowei　Jiang Deming(College　of　Energy　and　Power　Engineering，Xian Jiaotong University)Abstract　A simple diaphragm injection carburetor (DIC) is developed and patented in the paper.The principle is that,as the function of the diaphragm mechanism,pressure difference between two sides of the metering hole equals the vacuum of the venturi,so the pressurized fuel metering can be realized by the fuel metering hole,vacuum from the venturi,and fuel injection.The fuel is injected into the feed port and mixed with the small fraction of air through the port,the main port of fresh air from the crankcase is injected to the cylinder with the scavenging organized so that a separating layer is created between the exhaust port and feed port,it can substantially reduce short-circuit loss of fuel-air mixture.The combination of the low load fuel supply system of a conventional carburetor with the DIC which functions at high load operation is also studied and presented,which makes the structure of the whole fuel system simple and is of great significance for development and application of small two stroke spark-ignition engines.The basic idea and principle of DIC are described in the paper.Test results on a 30 cm3 modified engine are presented,including characteristics of fuel supply and engines performance comparison with conventional　carburetor engine.