Study Of HCCI Combustion Based On VVT & VCR Prototype

With the international energy situation becoming increasingly tense, people's increasing demand for environment,The voice of energy saving is becoming higher and higher. So the exhaust of automobile has become a focus of attention. Many countries have formulated strict emissions regulations. In order to meet increasingly stringent regulatory requirements, A new combustion engine - homogeneous charge compression ignition (HCCI) engine become a popular technology research. This paper has studied this technology on a single zone HCCI combustion model with negative valve overlap (NVO).This paper introduces the VCR & VVT prototype firstly. The introduction includes the function of VVT&VCR, the transforming of valve timing and ignition system. Secondly this paper propose the defects of this VVT mechanisms. It will result in a effective compression ratio and expansion of power loss if we achieve NVO by this VVT mechanisms. So in this paper we design a new variable valve lift and timing mechanisms (VLT), and establish a EXCITE TD model for it. Then output the lift curve with different valve timing and valve lift.Based on these mechanisms-VVT&VCR&VLT, The author establish a coupled chemical kinetic mechanism single zone HCCI combustion model through the AVL-BOOST and CHEMKIN software. This HCCI combustion model is established in a SI model that has been calibrated, only changed the combustion module. This HCCI combustion model coupled a PRF mechanism released by Shigeyuki Tanaka. This mechanism can effectively simulate the start and duration of combustion , but can not simulate emissions performance of HCCI combustion.Through this HCCI model, This paper predict the HCCI operating range of this prototype under the conditions of 2500rpm, compression ratio 14, air-fuel ratio 15. And this paper study the influence of the chamber EGR rate, compression ratio, air-fuel ratio to HCCI Combustion.