汽车继电器触点瞬态接触行为分析及数值模型建立

继电器是车辆电器控制的一种重要元器件,其工作环境是瞬间大电流通过周期性闭合的触点,由于接触触点间接触电阻在闭合瞬间大电流的作用下产生焦耳热,导致触点极易发生熔焊的可能,严重影响继电器的使用性能,危害行车安全。继电器触点间接触行为是影响其接触电阻的关键因素。为此,本文基于Greenwood-Williamson模型建立接触力学数值模型,为探析触点间瞬态接触电阻奠定基础,为继电器热防护机构的设计及可靠性评估提供参考。     

问答6则

１　小红旗轿车电气设备中采用的双触点继电器结构与使用有何特点？ 答：继电器是用一个小电流信号来控制一个大电流电路的接通与断开。小红旗轿车电气设备中除使用常见的单触点继电器外，还设计使用了新式双触点继电器，其结构见图１。 双触点继电器主要由两对触点、电阻、线圈及片式插头等组成。其两对触点是并联工作的，其中一对触点由纯银制成，体积较另一对触点大；另一对触点由纯钨制成。在继电器吸合工作时，纯钨触点３先闭合接通电路，大约在 ４０ ｍｓ～５０ ｍｓ时纯银触点６才闭合。而在继电器断开时，纯银触点６先断开，过４０ …     

一种新型长寿双触点汽车继电器的研究

电磁继电器是汽车上安装最多的电子元件之一,也是最易损坏的元件。传统的汽车继电器大部分采用单触点结构,触点基本上选用纯银材料或者是银基复合材料,几十年一惯制,没有大的改进。实践证明,汽车继电器由于长期工作在低电压,大电流状态下,在频繁的吸合、断开操作后,触点材料将发生相互的转移和侵蚀,由于材料转移大多发生在触点表面局部同一位置,因此触点表面极其粗糙,形状往往表现为凸凹不平,致使触点间的接触电阻不断增大,导致触点完全碳化,接触不良而失效,严     

长江CJ750摩托车点火系统的改进

长江CJ750型摩托车的点火系统为传统的触点式点火,由于初级电流是断电器触点接通和切断的,突出的问题是触点打开的瞬间,触点间易产生火花,将触点烧蚀,使接触电阻增大,造成初级电流减小,次级电压下降,火花能量减小。尤其是在发动机低速运转时,触点的烧蚀更加严重。同时,次     

喇叭工作时为什么要联接继电器

喇叭呜叫是靠汽车方向盘上的按钮来控制的。一般情况下单音电喇叭的工作电流是在2～7安培之间,个别厂家制造的喇叭工作电流还要大些。双音电喇叭工作电流是单音电喇叭的二倍,按钮处的电流将达到4～14安培,这样大的电流在按钮处产生的电弧,容易烧蚀按钮的接触表面。安装喇叭继电器后,由按钮来控制继电器线圈电流,线圈产生电磁吸力,将轭铁吸下,使触点闭合。工作电流     

一种起动继电器触点的电路保护措施

正1背景介绍由于起动电机的控制电磁阀为电机类感性负载,在断开瞬间,因起动电机的控制线圈电感的特性,会产生较大的反向电压(一般为额定电压的2~3倍),此反向电压对控制起动机电磁阀的触点存在一定的危害,影响其寿命。为提高起动继电器的可靠性,抑制起动继电器的负载触点在断开瞬间因起动电机线圈产生的反向电压对继电器触点引起的伤害作用,需要相应的继电器触点保护措施。为此,本文详细介绍了一种简单、高效的保护措施。     

西德汽车交流发电机和调节器(下)

七、振动式调节器振动式调节器优先与小型的交流发电机配合使用。它周期性地打开和闭合触点而控制磁场电流。调节器不工作时因弹簧张力作用使动触点压向固定触点,一旦输出电压超过规定值时,对输出电压敏感的电磁铁产生的电磁力,即克服弹簧张力使触点打开,此时,励磁电路便接入附加电阻,以限制转子中的励磁电流并使输出电压下降。当电压下降至调节电压时,弹簧张力克服电磁铁吸力,使触点返回闭合位置。这时调节电阻被     

一种重型汽车刮水控制系统及电机控制方法

目前,国内重型汽车刮水系统中的电机大都由组合开关上的刮水开关直接控制,电机经由线束和刮水开关形成"刹车"回路,实现电机的回位,电机"刹车"时产生的大电流极易在组合开关的触点间产生拉弧并烧蚀触点,故使组合开关的故障率居高不下。在满足电机正常控制的前提下,降低组合开关的故障率,本文介绍一种控制信号与驱动信号相分离且刮水器采用摩擦消耗来停车的刮水控制系统及电机控制方法。     

空心白金的应用与反映

空心白金亦称环状白金,在汽车发达国家早已普遍推广应用。其特点是将分电器断电器的两个触点,改变为一个空心的和一个实心的,使传统实心触点的点接触改成为线接触,因而接触面积增大了,相对地通过的电流增大、电阻减小、灭弧性好、点火容易。并且由于有了中孔增加了触点间的空气流通,降低了触点温度,氧化现象有明显改善,白金的使用寿命有了明显的提高。我厂是一个白金触点与断电器总成的专     

汽车电喇叭出问题三步骤快速解决

当按下转向盘上或其他位置的喇叭按钮时．来自蓄电池的电流会通过回路流到喇叭继电器的电磁线圈上，电磁线圈吸引继电器的动触点开关闭合．电流就会流到喇叭处。电流使喇叭内部的电磁铁工作，从而使振动膜振动而发出声音。     

一种新的适合于铝合金点焊的电流控制法

在分析铝合金点焊过程中电极烧损与飞溅机理的基础上，提出了一种新的电流控制法，在这种控制法中电流分为焊接状态稳定化脉冲和焊接脉冲，前是几个不连续的小幅值电流脉冲，主要是使表面接触均匀化，接触电阻稳定在一个较小值，后的作用是加热工件，形成熔核，试验表明，该控制法可以有效地减少飞溅的发生，使电极的烧损变慢，变均匀，在连续点焊中还可以提高焊点质量的稳定性并降低对工件表面处理质量的要求。     

Experiments and thermal-electrical analysis of buss bar and relay assemblies in junction blocks

A junction block (or electrical distribution box) is electrical equipment that has been densely assembled from components such as buss bars, relays, and fuses to control the electric current flow in vehicles. Joule heat is generated in these parts as a result of electrical bulk resistance and electrical contact resistance. The generation of heat increases due to the complex behavior of modern vehicle electronic systems. Overheated parts can be damaged during operation due to thermal energy. The thermal assessment of a junction block is an important issue in automobile development. We suggest a methodology to simulate the transient temperature distribution of buss bars and electrical relays in a junction block. A finite element formulation of a coupled electro-thermal problem, which includes the effect of Joule heating, is introduced to the simulation. Finite element analysis (FEA) and experiments at the component level of buss bars and relays are conducted to investigate the thermal performance of a junction block. To verify the accuracy of the FEA procedure, the temperature history obtained by FEA is compared with the results obtained from experiments. The thermal-electric analysis of a typical junction block assembly is also discussed.     

A study on high-speed rolling contact between a wheel and a contaminated rail

A 3-D explicit finite element model is developed to investigate the transient wheel–rail rolling contact in the presence of rail contamination or short low adhesion zones (LAZs). A transient analysis is required because the wheel passes by a short LAZ very quickly, especially at high speeds. A surface-to-surface contact algorithm (by the penalty method) is employed to solve the frictional rolling contact between the wheel and the rail meshed by solid elements. The LAZ is simulated by a varying coefficient of friction along the rail. Different traction efforts and action of the traction control system triggered by the LAZ are simulated by applying a time-dependent driving torque to the wheel axle. Structural flexibilities of the vehicle–track system are considered properly. Analysis focuses on the contact forces, creepage, contact stresses and the derived frictional work and plastic deformation. It is found that the longitudinal contact force and the maximum surface shear stress in the contact patch become obviously lower in the LAZ and much higher as the wheel re-enters the dry rail section. Consequently, a higher wear rate and larger plastic flow are expected at the location where the dry contact starts to be rebuilt. In other words, contact surface damages such as wheel flats and rail burns may come into being because of the LAZ. Length of the LAZ, the traction level, etc. are varied. The results also show that local contact surface damages may still occur as the traction control system acts.     

汽油机活塞组一气缸套整体耦合传热模型及应用

采用直接耦合的有限元分析方法对一汽油机的活塞组一气缸套系统的瞬态传热过程进行了研究。通过将润滑油膜假设为一维热阻，建立了活塞组气缸套整体耦合系统的三维传热模型，应用所开发的三维流体动压润滑分析程序对活塞环组沿周向瞬时变化的油膜厚度进行了计算与分析。以LJ377MV汽油机活塞组一气缸套零部件为对象进行了应用研究，获得了更为清晰的多部件间的相互传热关系。     

汽油机活塞组—气缸套整体耦合传热模型及应用

采用直接耦合的有限元分析方法对一汽油机的活塞组—气缸套系统的瞬态传热过程进行了研究。通过将润滑油膜假设为一维热阻,建立了活塞组—气缸套整体耦合系统的三维传热模型,应用所开发的三维流体动压润滑分析程序对活塞环组沿周向瞬时变化的油膜厚度进行了计算与分析。以LJ377MV汽油机活塞组—气缸套零部件为对象进行了应用研究,获得了更为清晰的多部件间的相互传热关系。     

电动车高压连接器的内接触结构

本文介绍了电动车高压连接器最近设计的一些内接触结构。一类是双螺旋曲线结构、线簧结构、多孔耐磨结构、片簧接触结构、弹性插孔结构的线接触,另一类是多触点接触环、具有阵列凸点的镂空连接管、新型的圆柱形冠簧直接实现点接触,二者都以降低接触电阻,提高载流能力为目的。弹性高压插头则可以与插座直接形成线性接触,不需要冠簧等中介体。     

Reduction of engine emissions via a real-time engine combustion control with an egr rate estimation model

Vehicle emissions regulations are becoming increasingly severe and remain a principal issue for vehicle manufacturers. Since, WLTP (Worldwide harmonized Light vehicles Test Procedures) and RDE (real driving emission) regulations have been recently introduced, the engine operating conditions have been rapidly changed during the emission tests. Significantly more emissions are emitted during transient operation conditions compared to those at steady state operation conditions. For a diesel engine, combustion control is one of the most effective approaches to reduce engine exhaust emissions, particularly during the transient operation. The concern of this paper is about reducing emissions using a closed loop combustion control system which includes a EGR rate estimation model. The combustion control system calculates the angular position where 50 % of the injected fuel mass is burned (MFB50) using in-cylinder pressure for every cycle. In addition, the fuel injection timing is changed to make current MFB50 follow the target values. The EGR rate can be estimated by using trapped air mass and in-cylinder pressure when the intake valves are closed. When the EGR rate is different from the normal steady conditions, the target of MFB50 and the fuel injection timing are changed. The accuracy of the model is verified through engine tests, as well as the effect of combustion control. The peaks in NO level was decreased during transient conditions after adoption of the EGR model-based closed loop combustion control system.     

MOS管在电动车窗开关上的应用

为解决24V电动车窗开关继电器触点易烧蚀问题,采用大功率MOS管作为控制电流通断的元件,开关内部的继电器仅用于对电流方向进行切换,MOS管先于继电器进行电流通断控制,因此继电器本身不参与电流的通断控制,继电器触点无电火花就不存在烧蚀问题,提高了24V电动车窗开关的可靠性。     

汽车座椅动态试验CAE分析及结构优化

通过构建某车型后排座椅骨架的有限元分析模型,根据欧洲经济委员会ECER17法规中关于座椅抗惯性的动态试验标准要求,对某汽车后排座椅进行抗惯性动态试验仿真分析。仿真分析结果揭示了座椅结构的应力集中位置,以及座椅结构中容易导致试验失效的薄弱环节,为正确设计以及合理调整改善结构方案提供了依据。通过优化设计,完善了产品的结构。