Study On The EMS Of FAI Two-Stroke DISI Engine

Two-stroke engine has its intrinsic advantages in terms of high specific power, compactness, light weight, low cost, etc. However, because it depends on mixture scavenging, which leads to fuel short-circuiting and excessive exhaust emissions in fresh mixture during the light load state, two-stroke engine is reaching an important appointment for its survival due to its high emission level and poor fuel economy. Theoretically, GDI(Gasoline Direct Injection) is an effective way to solve the short-circuiting problem, since it allows the introduction of the fuel separately from the scavenging air.A simple, reliable and cost effective FAI (Free Armature Injection) system is applied to a 98cc two-stroke engine in this dissertation. The combustion system for DISI is developed; a prototype engine is designed and then equipped on an AX-100 prototype motorcycle; and preliminary road tests are performed.Results of dynamometer tests demonstrate that, the method of intermitted injection can effectively reduce the HC emission and the fuel consumption during idling operation; With smaller bypass section, the inclined-tapered chamber is more appropriate to obtain better emission and fuel consumption;The two processes injection which brings on quasi homogenous combustion is quite available to optimize the function of lean burn mixture combustion. During heavy load operations, the injection timing should be advanced as much as possible, given the limit that the fuel injected can not directly pass out of the exhaust port, to realize homogenous combustion to provide higher torque output and reduce the HC emission and fuel consumption to a large extent.Software techniques such as circulatory restoration,dormancy and safeguard of electrical source broken together with hardware techniques including lowpass,separate supply and photoelectric insulation are available to intensify the reliability and the stability of the EMS.In a conclusion, the FAI system can completely remove the fuel short-circuiting, and greatly improve the performance during heavy load operating conditions. During light load operations, the fuel consumption and HC emission are reduced by adopting charge stratification. The FAI Tow-Stroke DISI with its EMS successfully improve fuel economy while reducing HC emissions largely at the same time.