Study Of The Motion Characteristics Of Reedvalves In A Two-stroke Gasoline Engine

Reed valve is the key component which controls the gas flow of crankcase and directly affects the output power and speed characteristic of two stroke engine. Reed valve need to complete opening and closing process in engine’s working process. When working frequently, reed valve could occur resonance. It would drive reed valve hit stop plate with larger force and the reed valve could break if working too much long time. So the nature frequency of reed valve need be studied to avoid resonance occur in design working condition of engine.The reed valve opening and closing process is completely controlled by the gas pressure difference before and after. When pressure in crankcase changes, it will affect the reed lift of reed valve, and when reed lift changes, it will reversely affect pressure in crankcase. So the motion of reed valve is a typical two way fluid and solid interactive process. Relative to the size of reed valve case, the deformation of reed is much big(up to a dozen millimeters). Realizing simulating two way fluid and solid process with big deformation in small space is very difficult. If the 3D fluid and solid interactive simulation model of reed valve could be established, it would help to design reed valve precisely and improve two stroke engine’s performance.Based on the sequentially coupled principle, establishing the reed valve fluid and solid interactive mode in Ansys Workbench14.0. The Fluent and Transient Structure software are separately used to calculate the fluid and solid part, and the System Coupling is used to exchange the data of fluid and solid part. This kind of coupled calculating method has clear iterative process and better convergence. Through lots of error processes, getting the dynamic mesh parameters which could guarantee the coupled calculating process run correctly when the fluid boundary deformation is big.Under the same steady boundary condition, the reed lift and flow calculated by fluid and solid interactive model are basically the same as the results of one dimensional model which is verified by the engine performance experimental data. It indirectly verifies the accurate of fluid and solid interactive model. The reed valve is used to calculate the opening process of reed valve under steady and transient boundary condition to analyze the dynamic characteristic of reed valve in opening process, which could lay foundation for optimization of reed valve and performance improve of two stroke engine.