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In modern four-stroke automotive engine technology, variable valve timing and lift control offer potential benefits for making
a high-performance engine. In this paper, a novel design named dual-mode electrohydraulic fully variable valve train (EHFVVT)
for both engine intake and exhaust valves is introduced. The system is mainly controlled by either proportional flow control
valves or proportional pressure relief valves, and hence two different families of valve displacement patterns can be achieved.
The construction of the mathematical model of the valve train system and its dynamic analysis are also presented in this paper.
Experimental and simulation results show that the dual-mode electrohydraulic variable valve train can achieve fully variable
valve timing and lift control, and has the potential to eliminate the traditional throttle valve in the gasoline engines.
With the proposed system, the engine performance at various speeds and loads will be significantly improved. 相似文献
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某高速汽油机改LNG发动机动力性下降问题研究 总被引:3,自引:0,他引:3
针对直接将汽油机改为LNG发动机导致的动力性下降问题,通过GT-Power与试验标定相结合的方法,提出了一种基于单因素法的高速LNG发动机配气相位优化方法:在降低泵气损失、减少缸内废气、提高充气效率的前提下,减小气门重叠角;针对优化后的配气相位,优化设计凸轮型线;同时根据LNG燃烧特性,在控制最高燃烧温度和压力的前提下,适当将点火提前角增大,合理组织燃烧,使燃烧更加及时完全,从而提高燃烧效率。结果表明,优化后的凸轮型线满足配气机构运动学动力学要求,高速LNG发动机最大功率较之优化前提高约7.9%,最低燃料消耗率降低约5.8%,此方法可以在一定程度上解决LNG发动机的动力性下降问题。 相似文献
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K. -B. Kim K. -W. Choi K. -H. Lee 《International Journal of Automotive Technology》2012,13(3):401-407
A relatively new approach for improving fuel economy and automotive engine performance involves the use of automotive combined
cycle generation technologies. The combined cycle generation, a process widely used in existing power plants, has become a
viable option for automotive applications due to advances in materials science, nanotechnology, and MEMS (Mico-Electro Mechanical
Systems) devices. The waste heat generated from automotive engine exhaust and coolant is a feasible heat source for a combined
cycle generation system, which is basically a Rankine cycle in the context of this study. However, there are still numerous
technical issues that need to be solved before the technology can be implemented in automobiles. A simulation was performed
to examine the amount of waste energy that could be recovered through the use of a combined cycle system. A simulation model
of the Rankine cycle was developed using Cycle-Tempo software. The simulation model was ultimately used to evaluate the rate
of waste heat recovery and the consequential increase in the overall thermal efficiency of the engine with the combined cycle
generation system under typical engine operating conditions. The most effective automotive combined cycle system recovered
68% of the waste heat from the exhaust and coolant, resulting in a 6% improvement in engine efficiency. The results are expected
to be beneficial for evaluating the feasibility of combined cycle generation systems in automotive applications. 相似文献
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氢燃料电池技术有可能为汽车、能源工业带来革命性的变化,毫无疑问会使汽车产业的竞争格局、能源供应方式发生根本变化。汽车产业价值链将出现重大的变革,价值链的核心不再是燃油、燃油发动机,而是氢燃料电池、储氢与供氢系统。本文建立氢燃料汽车价值链模型并进行了分析,氢燃料汽车电池、储氢与供氢系统将是新商业模式最大受益者;燃油、内燃机供应商、传统汽车制造商的前景将不容乐观,相关企业需从新的产业链找到位置和突破口,才能在变革中求得发展。 相似文献
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为探索车用汽油机点火智能控制的有效方法,对CS492Q汽油机进行台架实验,在得到汽油机性能与点火提前角关系的基础上,以汽油机曲轴转速变化量和转速相对于点火提前角增量的变化率为模糊输入量,点火提前角增量为模糊输出量,建立模糊控制器,对汽油机点火正时进行模糊控制仿真。结果表明,采用模糊控制技术调节汽油机的点火正时,对汽油机的各种工况都有较好的控制精度,对变工况过程有较好的适应性。 相似文献
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Won-yong Ki Seung-Jin Heo Dae-Oh Kang Hong Jae Yim Kyung won Lee Jung ho Kim Chang kun Lee 《International Journal of Automotive Technology》2017,18(3):429-437
The purpose of this study is to propose a concept design process for an automotive body structure using technical information on the major joints and members of vehicles. First, in order to collect the technical information on major joints and members, 17 vehicles were selected using benchmark data. The collected technical information for the selected vehicles was the cross sectional shapes of each joint and member which were used for the analysis of joint stiffness, crashworthiness and static stiffness of the member to make a database along with cross section properties. This study applied a ‘What If Study’ technique to perform a concept design of an automotive body using the analyzed information and selected cross section meeting the design objectives. The criteria for the selection of the cross section were defined by subdividing the defined design objectives of an automotive body structure and constraints into members and joints. In order to configure an analysis model of an automotive body structure using the selected cross section, a shape parametric model was used and static stiffness, dynamic stiffness and crashworthiness were assessed to evaluate the configured automotive body structure. The evaluation result showed that the crashworthiness and static/dynamic stiffness were improved compared to an existing body structure. In addition, the weight of the body structure was reduced. Through this study, the process that can rapidly and effectively derive and evaluate the concept design of an automotive body structure was defined. It is expected that, henceforth, this process will be helpful for the study of automotive body structures. 相似文献
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系统可靠性分配是供应链可靠性运作过程中的一类重要问题,对于供应链的成功运作具有十分重要的意义。文章借鉴机器零部件的可靠性分配方法,根据可靠性工程中可靠性成本函数的概念,构建了汽车供应链可靠性预估成本函数;结合供应链的结构特征,建立了汽车供应链可靠性的分配模型,最后构建了以重要度最大单元为搜索单元逐步迭代的算法。这种新的简易算法,更易应用于汽车供应链的可靠性分配,为汽车供应链的成功运作提供保障。 相似文献
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车用直喷式柴油机排气净化的途径 总被引:4,自引:1,他引:4
在改善车用柴油机燃油经济性的同时,需进一步降低氮氧化物和微粒排放,关键是进一步优化燃烧过程,减少有害排放物的生成,也要改善燃料品质,甚至进一步采用排气后处理技术,本文阐述了喷油系统和进气系统的改进,燃烧室设计的优化,增压中冷,废气再循环等技术措施的潜力,以及燃油改质,排气后处理等措施的效果。 相似文献
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介绍了基于飞思卡尔MC9S12XS128MAL单片机的电子驻车制动卡钳电控性能测试系统,具体阐述了电子驻车制动卡钳无液压夹紧释放功能、有液压夹紧释放功能、电机过载性和电机欠电性测试的实现方法。该测试系统采用完全不同于汽车行业现有团体标准规定的试验方法,以更接近实车工况的方式进行测试,测试方法和测试系统具有一定的创新性。试验结果表明,该系统输入电流、液压控制精准,卡钳夹紧力、液压、电流数据采集实时,试验测得的响应时间、夹紧力及动态关系曲线稳定可靠,可以满足各主机厂及零部件厂商对电子驻车制动卡钳电控性能试验的要求。 相似文献
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本文讨论制造误差对汽车结构动态特性的影响。由于制造误差,我们把汽车结构参数作为随机参数,利用随机参数结构的随机特征值分析理论来估计制造误差对汽车结构动态特性的影响。这个方法也可用于估计有限元分析和汽车结构动力学设计的可靠性。为了说明该理论的应用,本文以某汽车车架为例,作了分析计算,并得到了一些重要结果。 相似文献
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汽车发动机液阻悬置动特性仿真与实验分析 总被引:23,自引:2,他引:23
本文总结了发动机悬置系统的隔振要求和常用的悬置元件动特性评价参数,指出了悬置元件为满足高、低频隔振要求而产生的设计上的矛盾和困难。通过激振实验方法测试了液阻悬置元件及其橡胶主簧的动刚度和阻尼特性。对一种轿车动力总成液阻悬置建立了集总参数的力学和数学模型,进行了动特性仿真,并与实验测试结果进行了对比分析,表明该模型对液阻悬置的低频动特性分析很有效,在高频段也可以预测液阻悬置开始发生动态硬化的频率,对于液阻悬置产品的设计和改进具有指导意义。 相似文献
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Variable valve timing (VVT) and cylinder deactivation (CDA) are promising methods in reducing fuel consumption and emission at part load in SI engines. An SI engine which uses electromagnetic valvetrain (EMV) will eliminate flow restriction from the throttle valve and produce higher indicated mean efficiency pressure (IMEP) due to the disabling of some of the working cylinders at part load. Therefore, pumping loss can be significantly reduced at part-load conditions. In addition, duration and timing of valve events are variably controlled at different operating conditions. This contributes to the improvement of engine efficiency. In this study, a dynamic model of an unthrottled SI engine has been developed to simulate the engine cycle. The model uses an EMV system that allows valvetrain control and cylinder deactivation techniques to be carried out in simulation flexibly. The simulated results find the optimal valve timing for different engine speeds. The optimal timing of intake valve closing depends on engine speed linearly, while the intake valve opening insignificantly influences engine performance. Additionally, this study also shows that cylinder deactivation modes can be successfully applied in improving engine efficiency at different engine loads. Different cylinder deactivation strategies have been applied for the full range of engine loads. It is concluded that the two-cylinder deactivation mode (50% CDA) considerably improves fuel consumption at low engine load. Meanwhile, one-cylinder deactivation (25% CDA) is an optimal fuel economy mode at medium engine load. With proper uses of VVT and CDA strategies, the efficiency of an SI engine can be increased more than 30% at low engine load and 11.7 % at medium engine load. 相似文献
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