某船用发电机组柴油机飞车原因分析与排除

针对某船用高速柴油机发电机组飞车的原因进行分析,是由于调速器复位弹簧挂钩断裂,齿条油量位置失去控制,发生柴油机转速急剧升高,最终导致的柴油机飞车。并通过故障复现验证了原因定位,最后制定了预防措施并针对此问题进行了举一反三。     

客车空调钣金框架断裂分析及改进设计

针对某公司客车空调钣金框架发生断裂失效情况,运用Pro/Engineer建立了框架3D模型,并通过有限元软件ANSYS对其进行应力分析,找出了最大应力和应力集中位置。有限元分析的最大应力位置和应力集中位置和实际发生断裂的位置完全一样。在此基础上对断裂框架提出了改进设计方案,改进后的框架其最大应力较原有框架的最大应力有大幅度降低,同时解决了断裂位置的应力集中问题。在实验室振动台对改进后的框架进行振动测试,测试结果表明,改进后的框架没有发生断裂情况。     

基于有限元方法的排气歧管后法兰疲劳模拟计算

为了解决排气歧管后法兰断裂问题,重现故障模式并对优化结果进行验证,采用有限元分析方法对排气歧管后法兰进行疲劳分析。运用ABAQUS计算出各工况的Mises应力以及各主应力,并计算出危险位置的疲劳安全系数。可以看出:分析很好地再现了故障发生的位置。优化后模型的安全系数达到要求,并且通过了试验验证。     

基于疲劳损伤的某车型摆臂断裂问题分析

针对某车型摆臂总成路试过程中的异常断裂问题,通过分析确定此次异常为疲劳断裂,然后根据断裂位置及CAE分析结果,布置应力应变传感器,进行整车道路载荷谱采集测试。通过雨流数据处理及疲劳损伤分析,确定摆臂断裂原因,解决摆臂断裂问题,为今后其他项目的问题排查及分析提供指导。     

737NG前缘襟翼缝翼位置传感器分析

本文就737NG襟缝翼位置传感器系统做出了简介,随着新型飞机上使用钛合金材料作为传感器元件,针对737NG机队出现的襟缝翼位置传感器故障,指示异常,腐蚀等故障,各公司都对传感器的选材进行了改进,从而也减少故障发生。同时对运营人在维修中遇到的传感器的故障采取保留的具体操作。     

内燃机车柴油机典型曲轴断裂故障分析

曲轴断裂故障是柴油机常见故障,有外部因素也有内部因素。除因本身质量引起外,主要通过对内燃机车柴油机运用时曲轴的受力分析,再结合曲轴断面形状和断裂方向进行研究,找出两类典型曲轴断裂故障发生的原因,并提出针对性的控制和预防措施,以达到降低曲轴断裂故障的发生率。     

某型船用柴油机气缸套异常磨损原因分析

针对某型船用柴油机在装配试车时发生的气缸套异常磨损现象,进行故障原因分析,通过排查找到了故障发生的直接原因,并提出了相应的预防和解决措施。     

融合电控柴油机传感器数据的贝叶斯综合故障诊断网络研究

针对电控柴油机故障源多样性和不确定性的问题,对故障现象、状态数据提取及处理、贝叶斯故障诊断网络、故障源的先验概率获取、故障源的确定等方面进行了研究,在故障现象出现的情况下对如何有效确定故障源进行了分析和归纳,构建了融合传感器数据的电控柴油机贝叶斯网络综合故障诊断模型,提出了使用传感器数据技术检测电控柴油机工作状态,并结合经验法等估算出各类故障源的先验概率。通过运用贝叶斯网络技术推断查找到故障源的方法,并以丰田1KZ电控柴油发动机为实验对象,使用Hugin Expert工具对该诊断网络进行了推理验证。研究结果表明,该诊断网络充分发挥了传感器数据诊断技术的实时性和贝叶斯网络技术的判断决策能力,有效提高了电控柴油机故障诊断的正确率和实效性。     

采煤机截割滚筒行星架强度分析与改进

针对某煤炭企业服役的采煤机截割滚筒行星架出现的断裂故障,借助ANSYS仿真计算软件,对截割滚筒行星架强度进行仿真分析,结果表明,行星架出现断裂故障的原因是退刀槽位置存在应力集中。通过将行星架退刀槽深度减小0.3 mm,解决了行星架退刀槽应力集中情况。改进了行星架的应用,提高了滚筒工作的可靠性和寿命,降低了采煤机的故障修复时间,节约了运行维护人员及成本,增加了综采工作面内采煤设备的有效工作时间,减少了煤炭掘进成本,为煤炭企业创造了更多的经济效益。     

燃机电厂变频启动装置典型故障分析及其处理

介绍了燃机电厂变频启动装置的工作原理,并针对SFC出现的典型故障,如控制程序出错、励磁系统参数不匹配、位置传感器故障等进行分析,通过对故障的解决,提高了SFC的运行可靠性。     

某增压型汽油机催化转化器分析

在增压型汽油机的开发过程中,需要评估其催化器入口处的气流分布均匀性是否能够满足均匀性的评价标准。利用CFD软件,通过对某增压型汽油机催化器进行稳态分析,计算得到载体入口处的气流速度均匀性系数、氧传感器表面速度分布、总压分布等。结果表明:考虑涡轮机出口的旋流和废气旁通阀结构,得到的结果更准确;载体入口处的气流速度均匀性系数满足评价标准;氧传感器位于废气主流区,其布置位置合理;催化器的总压分布合理,压力损失在正常范围内。     

Measurement and analysis of angular velocity variations of twelve-cylinder diesel engine crankshaft

This paper presents the procedures for measuring and analyzing the angular velocity variation of twelve-cylinder diesel engine crankshaft on its free end and on the power-output end. In addition, the paper deals with important aspects of the measurement of crankshaft torsional oscillations. The method is based on digital encoders placed at two distances, and one of them is a sensor not inserted directly on the shaft, i.e. a non-contact method with a toothed disc is used. The principle based on toothed disc is also used to measure the actual camshaft angular velocity of in-line compact high-pressure pump the engine is equipped with, and this paper aims to demonstrate the possibility of measuring the actual angular velocity of any rotating shaft in the engine, on which it is physically possible to mount a toothed disc. The method was created completely independently during long-range development and research tests of V46 family engines. This method is specific for its particular adaptability for use on larger engines with extensive vibrations and torsional oscillations. The main purpose of this paper is a practical contribution to all the more interesting research of the use of engine crankshaft angular velocity as a diagnostic tool for identifying the engine irregular running.     

基于柴油发动机国六排放应用的氮氧化物传感器碳颗粒堵塞问题研究

针对目前国六柴油发动机应用的氮氧化物传感器被碳颗粒堵塞的问题进行了分析与讨论.为验证影响传感器积碳堵塞的内部和外部条件,采用了发动机台架和整车路试试验方法.通过总时长100 h以上的巴黎循环试验,测试分析了市面上两家主流供应商提供的氮氧化物传感器对于积碳堵塞的鲁棒性差异.试验结果表明:供应商1和供应商2氮氧化物传感器的...     

Fibre Optic Sensors for Long-Term Monitoring of Oil Film Pressure in Diesel Engine Main Bearing

The oil film pressure is one of the key parameters in journal bearings influencing the performance of the bearings. A fibre optic sensor was developed for online determination of actual oil film pressure under load without disturbing the actual tribological contact. Four optical sensors were integrated in a hydrodynamic journal bearing of a Wärtsilä Vasa 4R32 LN E medium-speed diesel engine with four cylinders, maximum power of 1,640 kW and rotating speed on 750 rpm. Online engine tests were carried out with different loads to study the sensor operation in real operating conditions. The engine tests were repeated six times over 4 years of operation reaching up to thousand hours of the engine use. The results showed differences in bearing pressure depending on the position of the sensor and on the operating cycle of the cylinders. The pressure peaks of all four cylinder work cycles could be identified in the measured pressure curves, and the pressure variations within the pressure curves fit well to the diesel engine’s work cycle and mass forces. The sensors had good repeatability over the whole test period.     

汽车发动机活塞敲缸探析

本文介绍了发动机活塞敲缸的经验诊断方法,通过求解CA1091汽车发动机活塞运动方程,得出了发动机活塞敲缸与结构参数、转速、负荷和润滑油粘度的关系,从理论上得到诊断发动机活塞敲缸的最佳转速、传感器安装部位、负荷和相位等。     

旋转电弧传感器的研制

介绍了电弧传感的基本原理及旋转电弧传感器用于焊接接头跟踪的工作原理。针对焊缝跟踪对传感器的要求，研制了一种适用于焊接机器人的轻便、紧凑、高速旋转的电弧传感器。详细介绍了高速旋转电弧传感器的旋转驱动电路、位置检测电路以及焊接电流采样电路。实验证明所设计的电路抗干扰能力强，旋转速度稳定，测位脉冲可靠，焊接电流的采集线性度好。该电弧传感器已在焊接机器人焊缝跟踪控制系统中得到成功应用。     

Detection and measurement of the inverse axial flow by means of the flying hot wire technique

In the reviewed literature about swirling flows through ducts of circular cross section, there are contradictions regarding the detection and measurement of the inverse axial flow generated in the center of a swirling flow. The main motivation for this investigation was to determine the existence of the inverse flow and the feasibility of measuring it by the flying hot wire technique using unidimensional and bidimensional hot wires driven with an intermittent linear servomotor with a maximum velocity of 2 m/s and with a distance trip of 0.595 m. The inverse flow was detected with both sensors but it was not constant during the maximum speed trip. The maximum speed and the duration of the inverse flow was obtained with the unidimensional sensor up to a radial position of 3 cm, although the axial position in which the inverse flow is detected, it is not the same in every radial position. Therefore, it is not possible to make a radial distribution of the axial velocity using only one sensor. Finally, in the center of the swirling flow there is an intermittent inverse flow similar to the recirculating flow that is generated in the wake of a body in relative motion to the fluid mass.     

汽油发动机爆震的原因与避免措施

发动机发生爆燃会使发动机动力下降、油耗增加、噪音加大、汽车舒适性变差、排放恶化,同时大大缩短发动机使用寿命。引起发动机爆燃的原因主要是:点火提前角过大、燃烧室过度积碳、发动机温度过高、空燃比不正确等。而现在采取的主要措施是在发动机机体上安装了爆震传感器,对发动机工作情况进行监测,通过ECU来控制点火提前角,从而控制爆震的了发生。     

Flow analysis of engine cooling system for a passenger vehicle

A numerical simulation is carried out to analyze the flow field of cooling air through the radiator and engine compartment. In order to consider the strong effect of the suction-type flow by the cooling fan at engine idling condition, a potential flow analysis is attempted by the assumption of a line sink located at the position of the cooling fan. The governing equations for steady two-dimensional, incompressible, turbulent flow are solved with the two-equationk-ε model for turbulence. The velocity profiles in the underhood engine compartment and around the front-end of a real vehicle are measured to compare with the numerical results. The agreement between the numerical and experimental results is fairly good. It is concluded that a two-dimensional computation is a fast and efficient tool for predicting the effect of front-end design on the cooling air flow through the radiator.     

Acoustic emission mapping of diesel engines for spatially located time series—Part II: Spatial reconstitution

In this study the characteristics of AE wave transmission around and through the cylinder head of a small four-stroke fuel injection diesel engine are investigated. Two sets of measurements have been carried out, one with simulated sources at various points on the cylinder head and one with the engine running, using a nine-sensor array. Propagation of AE waves from the simulated sources to the array sensor positions indicates attenuation factors of around 8.5. It is important to be able to estimate source–sensor distance accurately and this has been done using a threshold technique to identify the arrival time of a low frequency high amplitude wave at the sensors, then to deduce the wave speed from that information and hence calculate the source–sensor distance (transmission path length). Engine running tests were carried out and analysis focused on reconstitution of injector and exhaust valve opening events using signal mapping techniques. For injector events, the attenuation factors were similar to those measured from the simulated sources. For exhaust valve-opening events the attenuation factors varied between 5 and 7 with relatively poor correlation. This difference is thought to be due to variation in the actual source position during valve opening because the exhaust valve actuation involves a cam, push rod and rocker design. The results can be used to reconstitute the timing and amplitude of the AE emitted at the source which enables much more focussed monitoring of specific components and processes identified in the signals.