1、 全可变气门机构论文:基于进气门早关的无节气门汽油机泵气损失的研究【中文摘要】汽油机通过改变节气门的开度调节发动机的负荷。汽油机小负荷工况下,节气门开度较小,换气过程中的泵气损失较大,燃油经济性较差。为了改善车用汽油机在城市路况下即中小负荷的工况下的燃油经济性,国内外一直在研究可连续变化的全可变气门技术,实现发动机的无节气门控制,以减少泵气损失。全可变气门技术,在部分负荷时利用进气门早关或减小进气门升程的方法控制进入缸内的混合气,即可实现发动机的无节气门负荷控制方式,减少泵气损失,改善汽油机燃油经济性。本文研究的全可变气门机构发动机是在K157FMI 发动机的基础之上改装完成的。全可变气门机构
2、由凸轮机构和液压控制机构两部分组成,利用液压控制结构控制流体的流动来实现气门运动最大升程和开启持续角的可变。本文以 K157FMI 发动机为样机,对全可变液压气门机构的发动机进气过程进行了研究,主要内容包括以下两个方面:第一,在试验样机上,对全可变液压气门机构内部液压系统的压力波动进行了测量,研究了液压压力波动对发动机最高运行转速的影响。主要是通过在液压机构上安装压力传感器,测量发动机运行时的液压压力波动以及发动机的进气性能。通过改进使得 FVVT 发动机能有效工作在 5600r/min 的范围内。对全可变液压气门机构中的气门运动规律和各种工况下的发动机进气性能进行了实验测量。通过在配气机构中
3、安装 LVDT 位置传感器的方法直接测量得到气门的位置信号,再对采集数据进行处理获得气门的运动规律。实验结果表明本机构能够实现对气门运动规律的直接控制,可实现进气门升程 07.5mm 可变、进气门迟闭角 260A 范围内连续可调,实现了气门最大升程、开启持续角和配气相位的全可变。对试验样机进行倒拖实验,测量进气流量,并计算其充量系数。得到了不同气门运动规律下充量系数随转速的变化关系。从而验证了全可变气门机构发动机在整个工况下,可以通过控制气门运动规律来控制进入气缸的工质量以达到取消节气门的。第二,利用 BOOST 软件分别建立原发动机与 FVVT 样机的一维流动模型,对发动机的进气性能进行模拟
4、计算。首先通过在进气管安装压力传感器,采集获得原机与 FVVT样机各工况下进气管内的压力波动情况,通过实验结果与模拟结果的比较,修正模型;其次利用修正的模型模拟计算发动机缸内压力,从而计算发动机的泵气损失。最后,整理实验数据和模拟计算的结果,分析原机与 FVVT 样机的进气性能。根据分析得出:FVVT 机构可以取消节气门实现对发动机工况的调节,并大大降低发动机进气过程中进气系统以及缸内的真空度,从而减少泵气损失,提高燃油经济性。【英文摘要】The throttle is used in the traditional El engine to control the load. The thr
5、ottle percentage is small when the engine was working in the low load, at the moment the pumping loss of the engine is high and this results in high fuel consumption. at domestic and overseas, in order to improve fuel economy of the vehicle SI engine in the condition of low and middle load, a lot of
6、 work had been paid to the fully variable valve train technology which can be continuously controlled(without throttle)and reduce pumping loss. In the engine with fully variable valve train, the intake air is controlled by closing the intake valve early or decreasing intake valve lift, through this
7、way the engine can be controled without throttle, pumping loss can be reduced and fuel economy can be improved.The engine with fully variable valve train studied in this paper was abtained by fefitting based on a K157FMI SI engine. The fully variable valve train composes of valve train and hydraulic
8、 control mechanism. The continuous control of the max valve lift and opening duration of the valve are achieved through the control of liquidity of the hydraulic oil in the hydraulic control mechanism. In this paper, K157FMI engine is used as the experimental prototype, a series of studies on intake
9、 progress of engine performance with fully variable valve train was carried out. The main contents include the following:Firstly, the valve movement disciplinarian of the fully variable valve train and the intake performance under kinds of working conditions are measured on the test prototype. The m
10、ovement rules of valve is obtained through data processing of the signals of LVDT fixed on the valve train. The result of experiment shows that the FVVT can control the laws of valve movements directly:it can change the valve lift from 0 to maximum 7.5mm and make the valve timing change in 260CA aft
11、er TDC continuously, so as to make the maximum valve lift, Valve open continuous horns and timing phase fully variable. The intake efficiency was calculated through measuring the intake flow of motored engine with FVVT. Then the relationship between intake efficiency of different valve movement rule
12、s and the speeds is obtained. As a consequence, the throttle can be removed and the intake flow can be controlled by the fully variable valve train through the control of valve movement rules.Secondly, in order to simulate the intake performance, the cycle simulation model of prototype and the engin
13、e with fully variable valve train are set up with BOOST. The pressure fluctuation in the intake pipe was measured with the pressure sensor. Then the model set up before was corrected by comparing the results between the simulation and the experiment. Then the pressure in the cylinder was simulated u
14、sing the correctional model. So, the pumping loss of the engine was calculated.Lastly, experimental data and simulation results were analyzed, and the intake performance of prototype and the engine with FVVT was compared.The conclusion was got:the engine with fully variable valve train could make th
15、e vaccum in the intake pipe and cylinder decreased and improve the fuel economy by removing the throttle.【关键词】全可变气门机构 无节气门发动机 泵气损失 数值模拟【英文关键词】fully variable valve train None throttle engine pumping loss intake performance numerical simulation【目录】基于进气门早关的无节气门汽油机泵气损失的研究 摘要 9-11 ABSTRACT 11-12 第 1 章 绪论
16、 13-23 1.1 发动机全可变液压气门机构研究的目的和意义 13-14 1.2 发动机全可变气门机构的研究状况及技术特点 14-17 1.2.1 无凸轮轴驱动型气门 14-15 1.2.2 凸轮驱动型气门 15-17 1.3 无节气门发动机的研究现状 17-19 1.4 内燃机中气体流动数值模拟研究现状 19-21 1.5 本文的主要内容 21-23 第 2 章 内燃机循环模拟的理论基础以及 BOOST 模型的建立 23-45 2.1 缸内循环过程的热力学模型 23-29 2.1.1 基本方程 24-26 2.1.2 热力学模型计算方程 26-29 2.2 进排气管内气体流动计算 29-3
17、4 2.2.1 基本方程 29-33 2.2.2 进排气管道内气体流动偏微分方程的数值求解 33-34 2.3 无节气门发动机进气模拟计算的特点 34-37 2.3.1 FVVT 发动机的基本结构和工作原理 34-36 2.3.2 FVVT 发动机循环模拟计算的特点 36-37 2.4 原机与FVVT 发动机循环模拟仿真模型的建立 37-43 2.4.1 BOOST 软件简介 37-38 2.4.2 原机仿真模型建立 38-39 2.4.3 原机模型参数输入 39-42 2.4.4 FVVT 发动机模型的建立 42-43 2.5 本章小结 43-45 第 3 章 全可变液压气门机构发动机的实验
18、研究 45-65 3.1 FVVT 机构液压系统的研究 45-53 3.1.1 FVVT 机构液压系统压力的测量 45-46 3.1.2 压力传感器量程的选取 46-47 3.1.3 液压压力波动过程的分析 47-48 3.1.4 转速对液压压力的影响 48-51 3.1.5 液压系统的改进和结果 51-53 3.2 气门运动规律测量 53-56 3.2.1 气门运动规律测量的原理 53-54 3.2.2 测量结果及其分析 54-56 3.3 FVVT 发动机进气性能的测量 56-59 3.3.1 进气性能测量传感器 56-57 3.3.2 测量结果及其分析 57-59 3.4 进气压力波动的
19、测量 59-63 3.4.1进气压力波动测量原理 59-61 3.4.2 实验结构分析 61-63 3.5 本章小结 63-65 第四章 BOOST仿真模型的验证 65-77 4.1 原机 BOOST 模型的验证 65-73 4.1.1 原机无化油器时的进气压力波动 65-70 4.1.2 原机部分负荷下的进气压力波动 70-72 4.1.3 全负荷工况下的功率和扭矩 72-73 4.2 FVVT 发动机BOOST 仿真模型的验证 73-76 4.3 本章小结 76-77 第 5 章 FVVT 发动机的进气性能研究以及对泵气损失的影响 77-89 5.1 FVVT 发动机与原机进气压力波动的对比 77-82 5.2 FVVT 发动机与原机泵气损失的对比 82-86 5.3 FVVT 发动机与原机进气性能以及燃油经济性的对比 86-88 5.4 本章小结 88-89 总结与展望 89-91 参考文献 91-95 致谢 95-97 攻读硕士学位期间发表的学术论文及参与的科研项目 97-98 学位论文评阅及答辩情况表 98