一种连续可变气门升程机构的设计研究

发布时间：2018-04-11 13:48

本文选题：可变气门升程 + 凸轮型线　；参考：《广东工业大学》2016年硕士论文

【摘要】：进入21世纪以来,我国汽车工业发展迅速,汽车保有量大幅增加,车用的汽、柴油消费占比越来越大,由此带来的能源紧张问题更加突出。在此背景下,我国相继推出了第三、四阶段的汽车油耗法规,这对车用汽油机的油耗提出了更高的要求。连续可变气门升程技术(CVVL)是一种新型的车用汽油机节油技术,可以降低汽油机的泵气损失,提高汽油机的燃油经济性。本文设计了一种连续可变气门升程机构,并对CVVL机构的设计和原理进行了深入的探讨,本文的主要工作内容有：(1)在某2.0T发动机配气机构的基础上,提出了一种连续可变气门升程机构的设计方案,根据该CVVL机构的结构特点,设计了相应的凸轮型线,使气门在所有升程下都具有相同的缓冲段；另外,结合凸轮型线和气门目标升程曲线,计算了该机构中间摇臂型线。通过运动学验证,该机构的气门升程曲线满足相关设计要求。(2)利用GT-Power软件,建立了该CVVL机构的动力学模型,进行了动力学仿真,结果表明：气门的动力学特性良好,在气门最大升程、最大转速下,气门没有出现反跳现象,凸轮从动件也无飞脱；凸轮与控制摇臂滚轮接触应力偏大,并详细分析了应力偏大的原因,然后对整个CVVL机构布局进行了相关优化,优化后机构具有更好的动力学特性。(3)根据动力学计算结果,对机构中间摇臂和控制摇臂做了有限元分析,结果表明：中间摇臂局部出现应力集中,结构强度不够。因此对中间摇臂进行了优化设计,优化后的有限元分析表明,应力集中大幅减小,其结构强度满足要求,优化有效。(4)对该CVVL机构进行了样件试制工作,匹配设计缸盖总成,并在配气机构台架上做了稳定性试验,测量了气门的实际升程及凸轮轴驱动扭矩,试验结果良好。
[Abstract]:Since entering the 21st century, the automobile industry of our country has developed rapidly, the quantity of automobile ownership has increased greatly, the consumption of automobile gas and diesel has become more and more large, and the problem of energy shortage has become more and more prominent.In this context, China has introduced the third and fourth stages of automobile fuel consumption regulations, which put forward a higher demand for gasoline engine fuel consumption.Continuous variable Valve lift (CVVLV) is a new fuel saving technology for automobile gasoline engines, which can reduce pump loss and improve fuel economy of gasoline engines.In this paper, a continuous variable valve lift mechanism is designed, and the design and principle of CVVL mechanism are discussed. The main work of this paper is: 1) on the basis of a 2.0T engine valve valve mechanism.A design scheme of continuous variable valve lift mechanism is proposed. According to the structural characteristics of the CVVL mechanism, the corresponding cam profile is designed, so that the valve has the same buffer section under all elevations.Combined with cam profile and valve target lift curve, the middle rocker arm profile of the mechanism is calculated.Through kinematics verification, the valve lift curve of the mechanism meets the relevant design requirements. (2) using GT-Power software, the dynamic model of the CVVL mechanism is established, and the dynamic simulation is carried out. The results show that the dynamic characteristics of the valve are good.At the maximum lift and rotational speed of the valve, the valve does not appear the phenomenon of rebound, nor does the follower of the cam fly off, and the contact stress between the cam and the control rocker wheel is too large, and the reasons for the larger stress are analyzed in detail.Then the layout of the whole CVVL mechanism is optimized. The optimized mechanism has better dynamic characteristics. According to the dynamic calculation results, the finite element analysis of the middle rocker arm and the control rocker arm of the mechanism is done.The results show that local stress concentration occurs in the middle rocker arm and the structural strength is not enough.Therefore, the optimization design of the intermediate rocker arm is carried out. The finite element analysis after the optimization shows that the stress concentration is greatly reduced, the structural strength meets the requirements, and the optimization is effective. 4) the prototype of the CVVL mechanism is trial-produced and the cylinder head assembly is matched and designed.The stability test of the valve valve and the driving torque of the camshaft are carried out on the bench of the valve distribution mechanism. The test results are satisfactory.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U464.134.3

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