交通事故频发使人们对道路交通安全的关注度日益提高,近年来高级辅助驾驶技术逐渐成为汽车行驶安全的研究热点.首先对常用的基于车辆相对位置(CCP)和跨越车道时间(TLC)的车道偏离预警算法进行研究;然后使用Matlab/Simulink设计了一种基于模糊算法的车道偏离预警;接着使用仿真软件Prescan搭建测试环境,即车辆传感器、交通场景、车辆动作等;最后设计联合仿真试验.试验结果表明:设计的基于模糊算法的车道偏离预警达到了设计标准,符合实际需求.
汽车起动机作为汽车起动的关键部件,由于其工作的特殊性,经常被视为故障频发的部件.基于汽车起动机的基本结构以及工作原理,对其关键零部件拨叉结构进行优化设计,同时也对其内部的行星减速器进行受力分析,以此来提高汽车起动机的整体稳定性.
通过建立涡轮增压柴油机米勒循环热力学分析模型,分析研究了有效压缩比对发动机性能的影响规律.米勒循环的热力学计算结果表明,随着米勒循环程度的减小,即进气门关闭角越接近下止点时,米勒循环效率越高;而在提前关闭角由大变小的过程中,循环效率逐步提高,但是提高的幅度逐渐减小直到关闭角接近下止点时,循环效率最大并停止提高.对增压柴油机所采用的增压米勒循环进行分析,结果表明,循环净功、最高燃烧温度和最大爆发压力随着有效压缩比的增大而线性增加,而循环效率则随有效压缩比的增大呈先增大后减小的趋势.因此,在增压米勒循环优化设计中,应根据实际使用工况对米勒循环有效压缩比进行选择,应考虑最高燃烧温度、爆发压力以及循环效率三者的综合效果.
针对某型号共轨喷油器在柴油机负荷阶跃烟度测试中,部分转速段出现瞬态加速烟大的故障,对故障件的总成性能数据及尺寸参数,进行了研究分析.结果显示,喷油嘴喷孔孔径、K系数等对柴油机瞬态加速烟大故障有较大影响,实施了改进方案并最终解决了该故障,为后续共轨喷油器批量生产的质量控制提供依据.
为应对柴油车颗粒捕集器(DPF)在复杂工况、维护成本、再生效果等方面的问题,开发了一种油基催化剂(FBC)的DPF再生技术.该技术构建了一套紧凑型的FBC智能喷射系统,采用自主集成开发模式,实现了油基催化剂自动加注的开发目标,通过发动机台架与整车功能试验对油基催化剂的性能与应用分别进行评估,实现了油基催化剂控制技术应用.自主完成了 FBC控制系统的集成开发与测试验证,满足了系统控制要求;试验结果表明,油基催化剂的DPF可以在500～530℃内实现完全再生.
对等压出油阀回油阀座面的不同加工方式进行了比较分析,结合实际生产中回油阀外圆及座面的加工情况,对外圆及座面的精密加工工艺进行了实际对比分析.结果表明,针对外圆使用高精度无心磨加工工艺可以缩短工艺路线,降低生产成本;针对座面使用托磨加工工艺可以提高座面精度及生产效率.
作为五部委联合发布八项核心技术之一,氢气循环系统技术路线逐渐从氢气循环泵转向引射器.然而,采用引射器技术路线的典型问题之一就是难以全功率覆盖,需要更为精细的引射器优化设计.主要研究二次流入口结构参数对引射性能的影响,基于Ansys-Fluent软件,采用混合湿氢气介质,体积分数分别为氢气81％、水蒸气11％、氮气8％,建立引射器三维物理模型及其数值计算模型,数值分析不同二次流结构参数对引射性能影响.计算结果表明:不同的二次流入口结构对引射性能影响较小,其机理为二次流结构制约着混合段的流动混合,导致混合程度不同,进而影响引射性能.上述结果能为高效、全功率覆盖车用燃料电池系统引射器的设计提供理论依据.
根据电动汽车动力电池的结构特点、充放电特性和使用因素,参考新标欧洲测试循环(NEDC)和中国轻型汽车行驶工况循环(CLTC)分析三元锂动力电池汽车和磷酸铁锂动力电池汽车在各种行驶环境下的使用工况,通过试验对比找出电动汽车在市区工况、郊区工况和高速工况下缩短动力电池寿命的影响因素,根据测试数据分析优化电动汽车动力电池使用方案,提出一套合理使用电动汽车动力电池的能量管理方法,避免电动汽车动力电池故障和热失控产生,有效延长电动汽车动力电池使用寿命,提高动力电池耐久性和安全性.
通过数值模拟方法,基于流体体积函数(VOF)多相流模型对某型柴油机喷油器喷油嘴偶件(以下简称喷油嘴)的空化穴蚀进行仿真,得到了喷油嘴产生空化穴蚀的关键区域,以及影响空化穴蚀的关键结构,仿真空化区域与可靠性试验结果基本一致.通过减小喷油嘴密封角度、增大喷油嘴压力室圆角半径、减小喷孔锥角,使得密封面处空化现象得到改善,喷孔处空化强度及空化区域明显减小.
由于工作频率高、压力波动大,共轨喷油器中控制阀的节流孔部分容易发生密封失效,导致喷油器性能急剧恶化.主要通过某型号共轨喷油器衔铁密封失效分析过程,阐述了共轨喷油器典型失效模式,确定了本案例的失效机理,制定了改进方案,该过程对共轨喷油器控制阀工艺设计和可靠性开发具有参考价值.
基于FIRE软件以某1.4T汽油缸内直喷(GDI)发动机为研究对象,对单侧进气道均质废气再循环(EGR)、下侧引入和侧面引入EGR回路3种方式进行模拟,并得到以下结论:3种方式在活塞经过下止点上行时会出现废气扩散加剧现象;单侧进气道均质EGR的模式获得的分层效果并不理想,在点火时刻火花塞附近区域的局部EGR率过高;降低EGR侧压力会对整体EGR率产生很大的影响,缸内大部分区域的局部EGR率趋于一致,火花塞附近区域局部EGR率相对较高.单侧进气道下侧引入EGR回路和均质EGR 2种分层方式的掺混趋势十分相似;进气道侧面引入EGR的分层方式对进气行程时的EGR分层有显著的改善,仅小部分废气从气缸中心一侧进入气缸,在175.曲轴转角(CA)时局部EGR率差达到80％,但是在点火时刻火花塞附近局部EGR率差仅能保持30％左右;增加了气流挡板之后,在点火时刻缸内仍可以保持接近30％的局部EGR率差,火花塞距离局部EGR率较高的区域也比较远;增加EGR回路直径后,点火时刻缸内EGR率差增加了 9％,总EGR率提高4.5％,火花塞附近区域局部EGR率在14％左右;转速升高后会使EGR分层效果变差,火花塞附近区域局部EGR率升高.
A performance and emission development method of non-road CN IV engine（rated power between 75 and 560 kW） and aftertreatment based on typical agriculture machine road spectrum. The method consists of three parts: target Setting, hardware matching and calibration. Performance targets are generally set based on engineering experience, emission targets are usually set by backward. For hardware matching, optimization of turbocharger matching is used to achieve optimal engine performance and lowest cost under different vehicle applications.For engine and aftertreatment calibration, it mainly includes the characteristic working points setting based on typical agriculture machinery road spectrum, design of experiment, calibration data optimal methods, test bench development for vehicle working simulation. These methods are used to improve the accuracy, prospective and effectiveness of development.The feasibility and effectiveness of the proposed methods are illustrated by taking the development of a four cylinders SCR engine used for combine as an example.
Through CAE simulation analysis, the variation of the contact width and radial holding force between the main lip and the valve rod of the valve oil seal with single rubber seal lip and multiple rubber seal lips under different pressure loads was studied. The leakage of valve oil seals of different rubber seal lip structures under the condition of alternating air pressure was measured by a special valve oil seal leakage test rig. The carbon accumulation of valves with different rubber seal lip structure was studied by engine bench test. According to the CAE analysis results, the three-lip oil seal with two lips and two lips has the best bearing capacity to the pressure load, and the contact width between the main lip and the valve rod and the radial locking force change the least with the positive and negative alternating pressure load. Under the pressure load of 0.4 MPa, the change rate of the contact width between the main lip of the three-lip valve seal and the valve rod is 0, and the radial force decreases by 2.5%. Under the pressure load of-0.4 MPa, the change rate of the contact width between the main lip of the three-lip valve seal and the valve guide is 0, and the radial force increases by 0.5%. According to the leakage amount and engine bench test results, the leakage amount of three-lip valve oil seal is stable, and the leakage variation of different samples can be controlled within 0.5 mg/h. After 2 000 h engine bench test, the valve matching the oil seal has almost no carbon deposition. The research results can provide guidance for valve seal selection and matching design.
The pressure limiting valve is used to protect the parts in the common rail system. When the rail pressure is abnormally high, the pressure limiting valve will open. It first defines the boundary conditions for the opening of the pressure limiting valve of a common rail system.The optimization calibration of integral freezing function in rail pressure control is proposed.Engine torque limiting function was used in fault mode, and completed the bench verification test of the fuel supply system. The results showed that it greatly reduces the risk of opening the pressure limiting valve.
CAN is a serial communication protocol, which is applicable to the site with high requirements for real-time processing, reliable operation of vehicle electromagnetic interference environment, cost efficiency and required bandwidth. The FlexCAN implements the protocol communication of controller area network. The paper mainly introduces the basic structure and working principle of the FlexCAN, it designs and implements the transmitting and receiving functions of the FlexCAN. To the key technical points in the implementation process of the FlexCAN, it conducts in-depth research and analysis. By combining the method of key point's comprehensive analysis and improvement with the implementing, the transmission success rate can be improved, and the problem in the process of receiving matching can be avoided. In particular, the software implement part makes FlexCAN convenient and efficient to use, which has a very good guiding significance for the subsequent improvement.
In cold areas, cold starting is an important part affecting the performance of engines. Heating the mixture in the cylinder by preheating plugs is one of the methods to improve the performance of cold starting of engines. This paper discusses the operating principle of preheating plugs and puts forward the control strategy of them. The control algorithm of preheating plug control unit（PCU） is developed by the model-based software development method, and the correctness of the control logic is verified by a tested case. It is verified that the simulation results of the PCU algorithm have a good agreement with design requirement.
预热塞是安装在柴油发动机气缸盖上的.根据柴油的压燃特性,为了便于在低温环境下顺利启动发动机及缩短启动时间,需要预热塞控制器控制预热塞,对喷射在气缸内的燃油进行预热,增加雾化效果,更加易燃.车载发动机预热塞控制器通过控制逻辑精准控制预热塞断续或连续的进行加热,有效地提高了柴油机在低温下的冷起动性能,同时起到了提高燃烧稳定性及降低排放的作用.
环境感知是自动驾驶汽车的三大基本系统之一,针对道路交通参与者的目标检测是环境感知系统的主要功能,随着人工智能领域研究发展,目标检测的精度与速率都达到新的高度.综合国内外研究文献,简述目标检测发展史,介绍基于深度学习技术的2D目标检测算法和3D目标检测算法,展望目标检测领域未来发展趋势.
