Design Of Compound Injection Air Intake Manifold For GDI Engine

Air intake manifold was the most critical component in the engine intake system. Plastic air intake manifolds successfully replaced the aluminum air intake manifolds for its good performance, lower weight and costs. This paper described a design of the 4G15GDI engine plastic air intake manifold.The main problem of GDI engine emission is unburned HC and NOx. The combustion with stoichiometric air-fuel ratio using compound injection and EGR stratification were developed to solve this problem. Compound injection technique could make the quasi-homogenous charge through the plenum assist injection and cylinder direct injection to reduce the HC; Stratified -EGR technique could stratify the recirculation exhaust and gas in the intake stoke to get the exhaust-gas-exhaust pie, then the EGR durability could enhanced and get high EGR rate to reduce the NOx. The combination of this two technique solved the GDI emission problems.In order to organize the reasonable airflow, 4G15GDI engine model was built using the BOOST. Based on the studying the influence of plenum volume, manifold length and diameter to the engine performance, the designing principle was released to get the basic parameter of intake manifold cavity. This paper designed the assistant injector position and stratified-EGR entrance, access roads and exit structure. In the process of building the 3D model of plastic intake manifold, CFD and ANSYS analysis indicates that this kind of design meet the requirement successfully.The plastic intake manifold cavities mold was designed with 3D designing software by which can make original samples quickly in the rapid prototype center. This sample was tested with steady flow test bench, the test item included the intake air consistency and the EGR stratification simulator comparative. The results showed that intake air consistency of the plastic air intake manifolds meet the requirement and EGR stratification can increase tumble intensity.