汽车前照灯雾气原理研究与应对措施

汽车前照灯配光镜内表面起雾问题是一个影响汽车照明和外观的重要课题,同时也是车灯行业的共性技术难题。为解决汽车前照灯配光镜内表面起雾而被客户误认为是进水的问题,本文通过水雾与水汽的形成机理,从前照灯温度场、气体流动场、材料特性等角度探讨前照灯雾气相应解决措施。     

汽车前照灯雾气形成的数值仿真及应对措施

正半封闭式前照灯内部的水蒸气遇冷会在配光镜内表面形成珠状凝结,影响前照灯外观和照明效果。文中利用数直仿真手段对前照灯进行腔内温度分析和腔内流场分析,仿真结果与售后失效及物理实验一致。对前照灯内部雾气凝结机理进行了分析,指出凝结产生的必要条件,为前照灯起雾的改进措施制定提供系统性思路。     

汽车前照灯起雾原理分析及优化方案研究

汽车前照灯起雾一直以来是行业里的难题,尤其在中国市场,用户对于起雾现象接受程度不高,极容易被客户理解成车灯进水,导致引发售后抱怨及售后索赔。当使用环境较为苛刻、车灯起雾面积过大的话也会一定程度引起光分布的改变,使得远近光有效亮度降低,影响交通安全性。本文从原理角度分析了汽车前照灯的起雾机理,并且通过对试验测量的整灯内的温度分布及在温湿度试验箱做的各车型车灯起雾状态分析,提出整体优化框架及四种可行措施、并进行了对比试验,为各大主机厂提供了解决此问题的有效思路。     

基于CFD的车身外流场数值模拟研究

计算流体动力学（CFD）技术应用到汽车外流场数值模拟计算中,克服了风洞试验的局限性,但存在着模拟方法不规范、精度较低、评价指标与维度也不明确等问题。文章面向车身外流场数值模拟的全环节,针对某车型汽车初步造型面（CAS）外流场模拟技术进行了梳理与分析,首先通过前处理软件对外CAS进行几何清理,搭建外CAS仿真模型,然后基于有限元软件STAR-CCM+进行汽车外流场CFD数值模拟技术,最后根据有限元仿真分析方法,得出汽车外CAS三维速度场、压力场和流线图,从而实现对车身周围流场分布、主要分离区域及空气阻力系数的计算与分析。文中的模拟分析与评价方法对整车开发前期提供了一定的参考作用、指导意义及价值。     

NHD-8101型前照灯检测仪的使用与维护

NHD-8101型前照灯检测仪用于检测汽车、摩托车等机动车辆前照灯的发光强度、灯高和光轴偏移量。该检测仪具备中文液晶显示界面,标准RS232通讯接口和模拟数据输出接口,并可快速分解为三大部分（底座、立柱和光接收箱）,具有便于移动、操作方便、测量准确等优点,适用于机动车检测站和流动检测线对机动车前照灯进行检测,也适用于汽车维修保养单位对机动车前照灯的光束照射位置进行调整和检测。     

汽车AFS系统车灯转角模型研究

为了提高汽车夜间行驶的安全性,对汽车前照灯的动态性能进行研究是很有意义的。以汽车的前轮转向角、车速为基础,以汽车的停车视距为依据,建立了汽车前照灯系统水平转角的动态数学模型,得出了车灯转角与前轮转向角、汽车车速之间的关系,并通过Matlab／Simulink进行了仿真。仿真结果取得了良好的预期效果,对汽车主动安全系统的进一步完善有着一定的参考价值。     

基于安全视距和PD控制的汽车前照灯随动控制策略的研究

针对国内汽车前照灯随动系统方面以理论研究为主而缺少工程应用开发的问题,对汽车前照灯水平随动系统的控制策略进行研究。建立数学模型,提出基于安全视距的角度算法,结合法规标准对角度算法进行条件限制,并通过PD算法对角度进行闭环控制,最后依控制策略制作系统样机并进行算法仿真试验和实车模拟试验。试验结果表明,该控制策略满足系统对实时性和误差的要求,并满足AFS法规的要求。     

汽车排气系统的流场分析与优化

给出了某汽车排气系统一维非定常流动的气体动力学方程组和三维模拟数学模型.建立了该汽车排气系统与发动机的联合模型,并利用此模型得到了排气系统进口温度、质量流量、密度等参数.以此作为边界条件,利用三维CFD软件对该汽车排气系统流场进行了模拟,找到了影响排气系统背压的关键结构并进行了优化.结果表明,模拟结果与试验结果吻合性良好,优化后排气系统背压由40.5 kPa降至30 kPa.     

降低前照灯进水起雾故障率的方法研究

通过调研汽车行业的前照灯进水、起雾现状,以某车型为例,从人、机、料、法、环6个维度,从根本上分析前照灯进水起雾的原因,并制定相应的优化对策,成功降低该车型的进水起雾故障率。     

基于CAN总线的智能前照灯控制系统设计

为了解决车辆夜间行驶转弯时安全性和传统前照灯灯光利用率低的问题,设计了一种基于CAN总线的能够提高车辆夜间行驶安全性的智能前照灯控制系统,即汽车自适应前照灯系统。介绍了系统整体的设计,给出了系统主要部分电路图的设计,以及主要程序流程图。根据相关法规和车辆转弯模型,推导出了前照灯转角与车辆转弯半径和车速的关系,进行了仿真,验证了数学模型的可行性,最后在硬件平台上进行了实验验证。     

CFD analysis of the flow in an automotive headlamp

In order to predict water condensation in an automotive headlamp at an early stage of the development process, CFD analysis of the flow in the headlamp was attempted.First, CFD analysis was conducted on the headlamp unit removed from a vehicle. The result was similar to the experimental result, thus the validity of this analysis was confirmed. Furthermore, water condensation in the headlamp on the vehicle was studied, based on the CFD analysis and the experiment. The results show that the water condensation in the headlamp is not only influenced by the velocity and temperature distribution in and around the headlamp, but also by the absolute humidity near the headlamp vents.     

汽车前风窗玻璃除霜除雾数值模拟分析和研究

利用CFD方法对汽车内部流场进行了模拟,定量分析了车内气流的速度、温度、湿度、以及车窗玻璃的温度和空气的传热量等参数,进而对汽车前风窗玻璃除霜除雾进行数值模拟,对其除霜除雾效率和效果进行分析,为汽车除霜除雾工程应用提供参考.     

Design of automotive headlamp with high-power LEDS

A novel vehicle headlamp low beam system is presented. The optical system is composed of three identical cells to ensure enough illumination. A poly-ellipsoid reflector and a aspherical lens are used to concentrate the rays and a baffle is employed to produce the cut-off line. The optical performance shows a good agreement with the requirement for headlamp in Chinese national standard. The smart constant current driver sustains automotive headlamps?requirements, moreover it has high power efficiency. The performance of three kinds of cooling systems with different structures are simulated and evaluated by FloTHERM software. Then a loop heat pipes combined with fins cooling system is manufactured for cooling the designed LED headlamp. It can greatly improve the cooling efficiency. Even in the 80°C environmental temperature, it can meet the working requirements of LED headlamp low beam system, so it is a kind of feasible cooling scheme.     

汽车前灯结雾分析及解决措施

车灯内部结雾是影响车灯质量的一个主要问题,同时也是一个世界性难题.空气中的水蒸气遇冷凝结在车灯灯罩内表面,不仅影响车灯外观,而且使车灯的照明效果大打折扣,影响行车安全.车灯结雾涉及流动、传热、材料及结构设计等方面的问题.本文是从热设计的角度对车灯内部流动场、温度场和浓度场进行分析,进而来探讨车灯内部结雾问题并采取措施进行解决的.     

某高强化柴油机进气道的设计开发

以未简化的某柴油机进气道为研究对象,使用三维流动力学软件完成了气道稳流试验台中气道-气缸流动的三维数值模拟计算,模拟计算的流场显示出了在气道试验台条件下空气流动过程的详细状况,气道性能评价参数(流通系数和涡流比)的流动计算结果与气道试验结果吻合较好.数值模拟精度表明,气道CFD计算可以为发动机开发中气道设计提供理论依据...     

3气门摩托车汽油机进气流动特性模拟

应用CFD对具有两个进气道的某3气门125 mL单缸汽油机气道内流场进行了数值模拟,在气缸横切面速度分布图上发现两个进气门的下方会形成两个尺度较大的横向空气流动漩涡;同时在纵切面速度分布图上发现明显的纵向气流漩涡流动,获得了不同升程下的进气流量系数;并将计算结果与试验结果进行了对比分析。结果表明,所选模型和计算方法正确,可以利用数值模拟计算代替试验测试得到进气门流量系数。     

柴油机伞喷喷嘴内部流动的数值模拟

对柴油机伞喷喷雾及喷嘴内部流动的研究现状进行了分析,利用三维计算流体动力学(CFD)程序对喷嘴内气穴多相流计算模型进行了验证,在此基础上对柴油机伞喷喷嘴内部的流动特性进行了模拟计算分析。结果表明,在伞喷喷嘴喷孔进口处形成不对称的气穴,并逐渐延伸至出口处,从而对燃油雾化产生一定影响。     

4G15D缸内直喷发动机油气分离模拟分析及试验验证

某4G15D缸内直喷发动机由于在缸盖罩位置布置高压油泵,导致气缸盖罩油气分离部分空间被占用,需要重新设计该款缸内直喷发动机油气分离结构型式。使用CFD仿真分析软件对发动机油气分离器内气液两相流场进行了数值模拟,分析了3种不同结构(改进前后)迷宫式油气分离器的流动分布、压力损失,采用离散模型模拟油滴粒子喷射,假定油滴粒子与壁面碰撞后即被捕捉,进而得出不同直径油滴的油气分离效率,根据仿真分析结果选择最优化设计方案;设计了一种简单而有效的试验方法对油气分离器分离效率间接进行验证。结果表明,采用CFD软件模拟计算方法能够计算出油气分离器油气分离效率,获得的结果反映了流动本质。在模拟分析过程中,油滴直径设定在1～15μm范围内时,根据所需要的油气分离效率优化设计油气分离结构,满足了最终产品要求。同时,在计算分析准确的前提下,提出了相应试验验证方法。     

Numerical and experimental investigation of lubricating oil flow in a gerotor pump

Gerotor pumps are widely used in the automotive industry for engine oil lubrication, due to their high volumetric efficiency and smooth pumping action. In many cases, the lubricating oil from the sump is mixed with contaminants, such as dust and tiny solid particles, or becomes thickened, due to aging. These problems will lead to critical situations, such as increased noise, enhanced wear and erosion, and poor lubrication of the engine. These critical situations were studied by conducting a detailed CFD integrated investigation on a gerotor pump’s performance at different operating conditions in three phases, and the results are presented in this paper. In first phase, a CFD model of a gerotor pump was developed with a dynamic mesh for the rotary movement of both the inner and outer rotors. The effects on pump flow rate of important parameters, such as rotor speed, fluid viscosity and number of ports, were simulated using non-contaminated oil at room temperature and an elevated temperature of 140oC. The relationship between flow rate and pressure at different rotor speeds was predicted and validated with test data for further parametric study. The pressure ripples at different time steps were measured at different angular positions of the rotors to examine the model accuracy. It was found that the flow rate increased and pressure pulsation, as well as flow recirculation, was reduced when ports were added to the cover plate. A suction pipe with a strainer was added for the second phase to capture the undesired changes in flow behavior, such as cavitation, which is caused by negative suction at the inlet region of pump. A suitable size for the inlet suction pipe for this pump was chosen after performing tests to characterize the flow behavior with single and double ports. Next, the relationship between pressure drop and strainer porosity was determined using different porosity values for the strainers. In the final phase, oil with different concentrations of solids was simulated to measure the effect of solid particles on flow rates and pressure losses. It was observed that the intensity of the recirculation was reduced at the suction end at the higher concentration of 0.04%, due to particle inertial effects. It was also found that particle size distribution affected the overall efficiency and pressure head of the pump.     

汽车灯配光镜中环面的光路计算

环面是汽车前照灯配光镜中广泛应用的一种面形，其光路计算法的优劣直接影响配光镜ＣＡＤ程序质量。本文给出一套全新的环面光路计算式，经对四种不同的前照灯所在的２００多万条光线的计算表明，这套光路计算法是适定的，快速收敛的。