发动机可变气门相异升程基础理论研究

This project was based on the technique applied on the patent of four-valve engine different lift of valve(DLV) , and the technique of variable different lift of valve(VDLV) was put forward further, so the demand of different working conditions on air motion can be satisfied by changing the difference of two intake valve lifts via adjusting intake cam different angle in a real-time way. The project would be explored maily on the content as follows: (1) Studying on the theory and kinetic characteristics of four-valve engine intake cam different angle in-time adjusted mechanism by simulation and experimental investigantion, and developing its experiment system accordingly. (2) Investigating on the relationship between different angle of intake cams and air motion parameters including inclined swirl ratio, swirl angle, etc. in cylinder by engine flow rig and anemometer system.(3) Researching on the relationship between the air motion form under variable different lift of valve condition and combustion, exhaust and performance of engine, so the effect of the adjustment of intake cam angle on combustion, exhaust and performance of engine could be uncovered. Innovation point: By exerting an adjutable different phase way on engine intake valve to change the difference of the intake valve lifts, so the air motion in cylinder can be controled and organized, which could help solve the contradiction between the motion organization of air in cylinder and intake flow coefficient, and could help realize the full optimization of engine performance..

本课题以四气门发动机进气门相异升程专利技术为基础，进一步提出可变进气门相异升程技术，通过四气门发动机进气凸轮相异角实时可调改变两个进气门的升程差来满足发动机不同工况对缸内气体运动的不同需求。主要研究内容：（1）通过仿真与实验研究四气门发动机进气凸轮相异角实时可调机构原理与动力学特性，开发相应的相异角可调机构实验系统。（2）利用发动机气道试验台及热线风速仪研究进气凸轮相异角与缸内气体运动参数之间的关系，包括斜轴涡流比、涡流倾角等参数。（3）利用发动机台架试验研究可变气门相异升程下缸内气体运动形式与发动机燃烧、排放及性能之间的关系，从而明确凸轮相异角调整对发动机燃烧、排放及性能的影响。创新之处为，通过发动机进气门实施可调差异相位改变进气门升程差来实现对发动机缸内气体运动的调控组织，可有效平衡缸内气体运动组织与进气流量系数之间的矛盾，同时亦可实现对发动机性能的全面优化。

在四气门发动机进气门相异升程专利技术基础上，提出了可变进气门相异升程技术方案，即通过调整进气凸轮相异角改变气门升程差，满足发动机不同工况对缸内气体运动的不同需求。通过仿真研究了可变气门相异升程配气机构的动力学与运动学特性，设计了相异角可调机构；在气道试验台上研究了可变进气门相异升程时缸内空气宏观运动（涡流、滚流和斜轴涡流）形成特点及其变化规律。应用热线风速仪研究了发动机可变气门相异升程时缸内涡流流场，探明了缸内涡流与相异角之间的关系，为进一步研究可变进气门相异升程下缸内空气宏观运动和紊流特性对混合气形成、燃烧和性能的影响打下坚实的基础。