碗形塞过早损坏的原因与危害

EQ6100-1型发动机的缸盖铸件内腔为了清砂干净,前后端面各有一大出砂孔,顶面有两个小出砂孔,分别用塞片与碗形塞堵死。按技术要求,塞片与碗形塞的使用期应能保证车辆行驶15万km不漏水,然而在使用中常出现过早损坏即锈穿或密封不良造成渗漏冷却水的故障。塞片渗漏后水流在缸盖外部易发现,危害较少;碗形塞渗水对发动机的损害较大甚至发生活塞粘缸,烧瓦抱     

EQ6100发动机上碗形塞的作用与检修

东风EQ6100发动机缸体上装有8个碗塞(又称水堵)。在缸体右侧(即进排气歧管)下部,平行排列有5个(Φ52毫米);前后端面各有一个(Φ56毫米,修理用的Φ56.2_(+0.20)~(+0.10)毫米)。这些碗形塞孔的设计有利于清除缸体水套形砂,装上碗形塞后,将保持发动机缸体冷却水的密封。凸轮轴后端缸体座孔上的碗形塞(Φ56毫米),则用     

火花点火发动机碗型燃烧室的优化试验研究

介绍了在一台单缸电控汽油喷射发动机上进行的火花点火发动机碗型燃烧室的优化试验研究。试验结果表明,合理选择碗型燃烧室的结构尺寸,结合排气再循环提高压缩比,可改善发动机的经济性并降低排放。     

一种动力转向器油口防护密封塞结构设计

该设计提出了一种动力转向器油口防护密封塞结构,该油口防护密封塞由一体成型的头部、密封唇及螺纹段等部分组成.其中密封唇位于头部和螺纹段之间,且其直径大于头部和螺纹段.该动力转向器油口防护密封塞具有结构简单、零件数量少,可以同时满足动力转向器进出油口的密封与局部保护需要.     

预防球笼万向节早期磨损

我国目前引进的轿车结构,大多是FF型汽车结构,即是前轮前驱动结构。有发动机、离合器、变速器和减速器为一体,通过球笼万向节的作用,把转动的力矩传递给半轴,带动前轮运转,使车辆得到正常的行驶。整个动力和驱动装置都安装在前桥,为此,前桥结构非常紧凑合理。为了使球笼万向节密封,采用简单而不占空间的橡胶防尘套来密封球笼万向节,等于是简单的密封箱,这样使球笼万向节     

汽油发动机密封系统的开发及应用

针对发动机整机开发过程中密封件开发滞后的问题,提出了密封系统的设计概念,并根据发动机内部不同的密封介质,将其分为气体密封系统、机油密封系统和冷却液密封系统。在每个子系统里,梳理了重要的密封接口,并给出了相关密封件的材料选型和设计要求,使发动机密封系统开发与发动机整机开发同步,可以减少后期因无法满足密封需求而带来的泄漏问题。     

摩托车水冷发动机气缸头密封垫的优化设计

近年来,摩托车水冷发动机在三轮车和全地形车上得到广泛应用,由于水冷发动机气缸头密封系统是双向密封,结构较复杂,既不能让冷却液漏入机油中,也不能让机油或气漏入冷却液中,因此,发动机故障率相对较高。通过对摩托车水冷发动机市场出现气缸头密封垫烧蚀带来的系列问题进行分析,从气缸头密封垫的密封机理入手,对水冷发动机气缸头密封垫进行了优化设计,很好地解决了水冷发动机气缸头密封问题。     

浅谈摩托车化油器O型密封圈的设计

O型密封圈结构简单、密封可靠、成本低,在摩托车化油器中应用十分广泛,主要作用是静密封,有径向密封和端面密封。在实际应用中,O型密封圈常出现密封不严及装配困难等现象,因此在设计时应特别注意。     

利用偏心刀杆实现孔内倒角

摩托车发动机左曲轴箱盖(如图1)内安装有磁电机定子,磁电机输出线从左曲轴箱盖一φ14孔中穿出,因曲轴箱盖内有机油,所以磁电机输出线上带有橡胶密封塞(如图2),为了便于装配并保证密封性能,曲轴箱盖φ14孔的下部要求1.5×45°的倒角。一般孔外倒角加工方法简单,但对于有密封要求的孔内倒角,采用传统的办法较复杂,并且已不能满足机械行业对高效益、高质量的要求,造成的经济损失也较大。一、传统的加工方式孔内倒角一般采用手工和半手工操作来完成,刀具结构大致如图3。在刀杆2上开一异形槽,用螺钉1将倒角     

发动机凸轮轴后端盖密封失效分析及优化

针对某型发动机开发试验中出现的凸轮轴后端盖密封失效问题，应用非线性有限元软件ABAQUS对后端盖、密封垫以及缸盖组成的整体系统进行了数值模拟，得到厂后端盖的变形和密封垫的压力分布。试验结果表明。导致密封失效的主要原因是后端盖刚度设计过低．对后端盖进行了结构优化，并进行了仿真和试验验证。结果表明，经优化后的凸轮轴后端盖能满足密封要求。     

二甲醚发动机用直列隔膜式燃料泵的开发

以二甲醚发动机低压共轨燃油系统为对象,针对二甲醚燃料易造成柱塞式喷油泵柱塞偶件磨损和泄漏的问题,设计开发出一种二甲醚发动机用直列隔膜式燃料泵,阐述了其结构设计方案和工作原理,分析了关键部件。该泵采用发动机直接驱动和柱塞往复运动挤压隔膜的工作方案,具有结构简单特点,仿真分析表明,流量及压力脉动小,能满足车用小型化的要求,为深入开展二甲醚发动机低压共轨燃油系统的研究提供了设备基础。     

Two-dimensional laser induced fluorescence measurement of spray and OH radicals of LPG in constant volume chamber

It is recognized that alternative fuels such as liquid petroleum gas (LPG) have less polluting combustion characteristics than diesel fuel. In this study, LPG was injected into a high pressure and temperature chamber to reproduce the stratification processes in an engine. The spray images were taken by the use of a PLIF method with Nd:YAG laser to analyze their penetration and evaporation characteristics. Also the characteristics of combustion were investigated by simultaneous visualization of OH radical and flames.The results show that the mixture moves along the impingement wall that reproduced the piston bowl and reaches the ignition spark plug. Also, OH fluorescence rises sharply and then decreases gradually when the combustion is carried out actively.     

Low temperature premixed combustion within a small bore high speed direct injection (HSDI) optically accessible diesel engine using a retarded single injection

An optically accessible single-cylinder high speed direct-injection (HSDI) Diesel engine equipped with a Bosch common rail injection system was used to study low temperature Modulated Kinetics (MK) combustion with a retarded single main injection. High-speed liquid fuel Mie-scattering was employed to investigate the liquid distribution and evolution. By carefully setting up the optics, three-dimensional images of fuel spray were obtained from both the bottom of the piston and the side window. The NOx emissions were measured in the exhaust pipe. The influence of injection pressure and injection timing on liquid fuel evolution and combustion characteristics was studied under similar fuel quantities. Interesting spray development was seen from the side window images. Liquid impingement was found for all of the cases due to the small diameter of the piston bowl. The liquid fuel tip hits the bowl wall obliquely and spreads as a wall jet in the radial direction of the spray. Due to the bowl geometry, the fuel film moves back into the central part of the bowl, which enhances the air-fuel mixing process and prepares a more homogeneous air-fuel mixture. Stronger impingement was seen for high injection pressures. Injection timing had little effect on fuel impingement. No liquid fuel was seen before ignition, indicating premixed combustion for all the cases. High-speed combustion video was taken using the same frame rate. Ignition was seen to occur on or near the bowl wall in the vicinity of the spray tip, with the ignition delay being noticeably longer for lower injection pressure and later injection timing. The majority of the flame was confined to the bowl region throughout the combustion event. A more homogeneous and weaker flame was observed for higher injection pressures and later injection timing. The combustion structure also proves the mixing enhancement effect of the liquid fuel impingement. The results show that ultra-low sooting combustion is feasible in an HSDI diesel engine with a higher injection pressure, a higher EGR rate, or later injection timing, with little penalty on power output. It was also found that injection timing has more influence on HCCI-like combustion using a single main injection than the other two factors studied. Compared with the base cases, simultaneous reductions of soot and NOx were obtained by increasing EGR rate and retarding injection timing. By increasing injection pressure, NOx emissions were increased due to leaner and faster combustion with better air-fuel mixing. However, smoke emissions were significantly reduced with increased injection pressure.     

某轻型卡车线束插件烧蚀原因分析与改进

本文针对某轻型卡车发动机线束接插件烧蚀问题,通过对可能引起插件烧蚀的各种因素进行分析,找到导致该车型发动机线束插件烧蚀的根本原因,通过对插件的护套结构和端子进行改进,有效的解决了发动机线束接插件烧蚀问题,加强了整车电气系统的安全稳定性,并为以后的设计和类似问题的解决提供了技术参考。     

利用创新理论改进柴油机球形接头结构的研究

针对柴油机低压管路中普遍采用的球形接头密封结构存在的"跑冒滴漏"问题,利用知识管理结合创新的方法、创新的思路,解决工程中的实际问题.球形接头渗漏属于典型的技术归零问题,采用了"故障诊断和排故"流程进行求解.首先利用系统分析和问题分解对球形球头渗漏问题进行分析研究,查找问题的根本原因,形成分解图,构建故障结构组件模型;然...     

康明斯6BT柴油机窜气问题的研究

介绍了窜气对柴油机性能的不利影响,通过活塞环密封系统的动力学分析,阐述发动机窜气产生的内在机理,并给出了计算发动机窜气量的公式。     

火花塞的鉴别及常见故障检修

详细阐述汽车发动机火花塞的技术要求、火花塞工作不正常症状,同时指出外观鉴别火花塞和测试法,以及火花塞的常见故障及维护调整方法。     

一汽锡柴电控共轨国Ⅲ柴油发动机及其整车电路（Ⅰ）

介绍一汽锡柴国Ⅲ电控共轨柴油发动机的分类,列出几种锡柴国Ⅲ电控发动机电路,以装载CA4DF3-15E3发动机的CA6102SH2Y客车整车电路为例,详细阐述其电控系统功能,线束及插接件,故障诊断方法及步骤,电气维护等。     

简易法确定发动机缸孔泄漏点

表面或内部泄漏是缸体、缸盖最常见的故障之一。泄漏产生的原因有砂眼、气孔、裂纹等，而确定泄漏点、并将故障件维修处理是此类问题的关键。通常较大的砂眼或气孔（直径1mm以上）、裂纹肉眼或者借助漏液痕迹，都能找到相应的泄漏点，而较小的泄漏点、且出现在缸孔内部、缸盖燃烧室用常规的办法很难确定，有时需要用到专用的检测设备，而缸孔内部的细小漏点用专用泄漏检测设备能识别零件泄漏测试不合格，但无法锁定泄漏点的位置。本文将通过一个故障案例阐述一种特别简易且适合查找发动机内部泄漏的漏点检测方式—即简易法漏点检测。     

点火时刻对甲醇发动机燃烧及非法规排放的影响

针对甲醇发动机低温冷起动困难,在1台由1130单缸柴油机改造而成的直喷火花点火甲醇发动机上,利用CFD模拟软件AVL-Fire耦合甲醇氧化反应机理,通过电热塞将进气温度加热到283K,研究了点火时刻对甲醇发动机低温(266K)冷起动燃烧及非法规排放的影响。结果表明:提前点火时刻能够使缸内混合气得到较充分燃烧,减少未燃甲醇排放,当点火时刻由8°BTDC提前到11°BTDC时未燃甲醇排放显著减少;提前点火时刻能够降低甲醛排放,当点火时刻提前到17°BTDC、缸内最高燃烧温度超过1 300K时,甲醛快速氧化,甲醛排放显著减少。