Specific engine performance and gaseous emissions characteristics of European test cycle and worldwide harmonized driving cycle for a heavy-duty diesel engine

This study compares the engine operating behavior and regulated gaseous emissions characteristics between the reference European cycles (ESC/ETC) and the worldwide harmonized driving cycles (WHSC/WHTC), which will be applied in the Euro VI heavy-duty diesel engine emissions regulations, for the diesel particulate filter (DPF) equipped Mercedes 12 L diesel engine. The speed and load distribution for two additional representative harmonized cycles which cover a more realistic operating range for a heavy duty engine were established to verify the engine performance over wide range of the cycle work, fuel consumption, and exhaust system temperature as well as engine coolant temperature for repeated validation tests. The WHTC, including an additional test with cold start and transient operation before the hot start, had a substantial influence on the THC, CO, NOx, and PM exhaust emissions levels because of the engine heat-up time and temperature rising characteristics of aftertreatment device. Moreover, the different engine operating conditions of the WHSC influenced on the specific engine performance and gaseous emissions behavior unlike those of the ESC. Finally, the statistical analysis results through repeated tests validated the stationary and transient cycles running at the fully warm-up condition, however, those of WHTC were closely dependent on the inclusion of cold start condition or aggressive acceleration gradient of engine speed and load trace.     

Optimization algorithm for diesel engine operating parameters based on a vehicle driving test cycle

For compliance with stringent exhaust emissions regulations, diesel engines have been equipped with electronically controlled components. Hence, there are various engine operating parameters that must be optimized, however optimization of these parameters is complicated. The objective of this research is to provide a new optimization algorithm for the diesel engine operating parameters with consideration of the vehicle control strategy. To optimize engine operating parameters, the concept of the vehicle-based optimization has been introduced. The engine response functions for performance and emissions were determined using the design of experiments, the response surface method and regression method with various engine operating parameters. Then, the engine operating points of the vehicle during the test cycles were analyzed, and the fuel consumption and emissions were estimated. Consequently, the engine operating parameters at each operating point were optimized to reduce the fuel consumption and the emissions such as NOx and PM by using the gradient method. Moreover, a new optimization algorithm enables to optimize engine operating parameters in various test cycle without additional engine experiment.     

Experimental study on the oil pump driving energy consumption and lubrication safety in a PFI engine under NEDC and WLTC

Journal of Mechanical Science and Technology - We studied the transient driving power of an oil pump for 1.6 L PFI engine in a passenger car under the new European driving cycle (NEDC) and...     

柴油机曲轴危险工况的确定及其静强度分析

利用MSC．Patran＆Nastran对柴油机曲轴整体进行三维实体建模、网格划分和静强度有限元分析。采用弹簧单元模拟主轴承支承，使计算模型更接近实际情况。在确定曲轴危险工况时考虑了弯扭的联合作用，以有限元结果为依据，提出了一种更准确地确定曲轴危险工况的方法，证明了曲轴最危险工况并非发生在再进气的上止点或曲柄销受气体力最大时。最后采用了等效应力法对曲轴进行了疲劳强度安全系数校核。     

Development of a cutting tool condition monitoring system for high speed turning operation by vibration and strain analysis

Cutting tool wear is a critical phenomenon which influences the quality of the machined part. In this paper, an attempt has been made to create artificial flank wear using the electrical discharge machining (EDM) process to emulate the actual or real flank wear. The tests were conducted using coated carbide inserts, with and without wear on EN-8 steel, and the acquired data were used to develop artificial neural networks model. Empirical models have been developed using analysis of variance (ANOVA). In order to analyze the response of the system, experiments were carried out for various cutting speeds, depths of cut and feed rates. To increase the confidence limit and reliability of the experimental data, full factorial experimental design (135 experiments) has been carried out. Vibration and strain data during the cutting process are recorded using two accelerometers and one strain gauge bridge. Power spectral analysis was carried out to test the level of significance through regression analysis. Experimental results were analyzed with respect to various depths of cut, feed rates and cutting speeds.     

A new method for measuring engine rotational speed based on the vibration and discrete spectrum correction technique

This paper presents an encoder-less method for measuring the rotational speed of a reciprocating engine. The proposed method obtains the rotational speed of the engine from the lowest harmonic frequency component of its vibration signals, and uses a discrete spectrum correction technique to improve the measurement precision. Results from bench tests and tests on real engines, each having a different number of cylinders, have proven that the proposed method can achieve an extremely high precision when the engine is working in a steady-state or small speed fluctuation condition. As compared to the encoder-based method for measuring engine rotational speed, which is often found in literatures, the proposed method uses a straightforward hardware which is easy to install, and is particularly suitable for use during routine inspection and maintenance of vehicles.     

Analytical approach to wear rate determination for internal combustion engine condition monitoring based on oil analysis

Wear has important, negative effects on the functioning of engine parts. Additionally, this situation is very difficult to evaluate accurately in oil analysis for engine condition monitoring. Original Equipment Manufacturers (OEM), lubricant suppliers and oil analysis laboratories provide specific guidelines for wear metal concentrations. These limits provide good general guidelines for interpreting oil analysis data, but do not take into account common factors that influence the concentration of wear debris and contaminants in an oil sample. These factors involve oil consumption, fresh oil additions, etc., and particular features such as engine age, type of service, environmental conditions, etc.In this paper, an analytical approach to enable a more accurate wear determination from engine oil samples is developed. The above factors are taken into account and an improved maintenance program for internal combustion engines based on oil analysis is developed.     

基于NI cRIO的柴油机转速控制的半实物仿真

为了开展柴油机信号的监测研究和开发柴油机的控制算法,选用与柴油机数学模型类似的直流电动机作为控制对象,构建了一个以NIcRIO为核心监控装置的柴油机半实物仿真试验平台.初步运用PID控制算法,在3种LabVIEW编程环境中进行了仿真测试,并给出了在实时响应最高的现场可编程门阵列(FPGA)环境下编写的监控程序.测试结果...     

LPG发动机行车无力原因分析与故障诊断维修

针对用于大型公交车的LPG发动机行车无力故障,从LPG发动机类型、LPG特性、LPG发动机工作原理及LPG公交车的维修情况入手,系统分析了导致行车无力的主要原因,通过典型维修案例,归纳总结了LPG公交车行车无力故障诊断维修方法与技巧。     

差动轮系液粘调速装置摩擦片的研究及工况分析

液粘调速离合器是一种新型调速装置,适用于大、中功率风机、水泵的无级调速,尤其适用于对大惯量的负载、空载和轻载的启动及缓慢加速。本文中的差动轮系液粘调速装置,是指近年来用于煤矿井下带式输送机的可控启动装置。该装置能够按事先拟定的理想加速度曲线和启动时间启动带式输送机,并满足带式输送机整体动态特性,且能降低胶带动张力。     

基于神经网络和瞬时转速的发动机失火故障研究

针对发动机在实际运行中经常会出现单缸或者多缸失火这种典型的故障现象,从发动机瞬时转速的角度出发,对发动机气缸受力与发动机曲轴瞬时转速之间的关系进行了理论研究,建立了其数学模型,利用Matlab仿真软件对瞬时转速曲线进行了仿真,确定并提取出了特征参数,比较了正常情况下和单缸不点火情况下瞬时转速曲线及其特征参数的变化,并把这些变化作为下一步诊断发动机失火故障的判断依据;最后,建立了一个BP神经网络并对其进行训练,同时把仿真数据和实例数据输入到网络中进行了理论验证和实例验证。研究结果表明,发动机的失火故障与发动机瞬时转速之间存在一定的关系,利用瞬时转速可以对发动机失火故障进行诊断;利用BP神经网络方法诊断发动机失火故障具有速度快、效率高的特点。     

A fault diagnosis approach for roller bearing based on VPMCD under variable speed condition

Essentially the fault diagnosis of roller bearing is a process of pattern recognition. However, existing pattern recognition method failed to capitalize on the nature of multivariate associations between the extracted fault features. Targeting such limitation, a new pattern recognition method – variable predictive model based class discriminate (VPMCD) is introduced into roller bearing fault identification. The VPMCD consider that all or part of the feature values will exhibit interactions in nature and these associations will have different performances between different classes, which is always true in practice when faults occur in roller bearings. Target to the characteristics of non-stationary and amplitude-modulated and frequency-modulated (AM–FM) of vibration signal picked up under variable speed condition, a fault diagnosis method based upon the VPMCD, order tracking technique and local mean decomposition (LMD) is put forward and applied to the roller bearing fault identification. Firstly, LMD and order tracking analysis method are combined to extract the fault features of roller bearing vibration signals under variable speed condition; Secondly, the feature values are regard as the input of VPMCD classifier; finally, the working condition and fault patterns of the roller bearings are identified automatically by the output of VPMCD classifier. The analysis results from experimental signals with normal and defective roller bearings indicate that the proposed fault diagnosis approach can distinguish the roller bearing status-with or without fault and fault patterns under variable speed condition accurately and effectively.     

基于ds PIC单片机的农业机械柴油机工况记录仪设计

设计了一种基于Microchip ds PIC33FJ128MC708A单片机的农业机械柴油机实时工况记录仪。主要通过ds PIC33FJ128MC708A单片机外接霍尔转速传感器、位移传感器、温度传感器以及CAN通讯接口等外设,实现对农业机械柴油机实际作业工况下主轴转速、油门开度、机油温度、排气温度等关键信息的获取,通过LCD显示模块以及SD卡存储模块实现对采集数据的实时显示与存储,从而实现对农业机械柴油机实际工况的采集记录。实际测试表明,数据采集、显示与存储功能正常,采集精度1%,最大连续跟踪记录时长150天,满足农业机械柴油机实际工况信息记录要求。     

基于运行状态信息融合的电站制粉系统实时优化研究

针对传统优化算法的不足,采用神经网络非线性在线建模技术,提出了一种基于运行状态信息融合的制粉系统实时优化算法。该算法基于资源分配网络获得制粉单耗与过程参数之间的非线性映射关系,在此基础上,建立起球磨机系统在线优化模型,并利用遗传算法对该模型进行寻优,获得优化运行参数,用以指导实际生产。优化结果表明,该算法能有效地降低制粉单耗,在节能优化的同时获得料位、出口温度和入口负压等可控变量参数的优化值。     

柴油机连杆动力学分析的新方法

认为连杆是刚体，作平面运动，手出运动方程；基于刚体平面运动理论，提出一种新的柴油机连杆动力学数值计算方法——转动惯量法；该方法进行连杆动力学分析速度快，计算精度也得到提高；通过证明可以发现“连杆多质量代替法”仅是该方法的一种简化形式。     

基于CFD技术的柴油机水流分配器计算分析

计算流体动力学是解决三维流动问题的有效手段.为解决某型柴油机水流分配器两个出口流量不均匀、出口流动阻力大等问题,提出了改进设计方案.为了验证改进方案是否满足使用要求,建立了三维计算模型,运用CFD前处理软件Gambit划分网格,同时采用标准k-ε模型及SIMPLEC算法,对水流分配器内流场进行了数值模拟分析.通过分析,得到了水流分配器的出口流量以及内流场压力、速度分布特性,找出了改进方案中存在的缺陷,并提出了进一步的改进建议.     

Adaptive combined HOEO based fault feature extraction method for rolling element bearing under variable speed condition

It is still a challenge for condition monitoring and fault diagnosis for rolling element bearings working under variable speed, while some conventional diagnostic methods are useless. Order tracking is commonly used as an effective tool of the non-stationary vibration analysis for rotating machinery and tacho-less order tracking may be more applicable for practical situations, while the key point is to obtain more accurate instantaneous rotating speed. What’s more, the collected bearing fault vibration signals always contain strong background noise that greatly affects the result of fault feature extraction. To solve these problems, a fault feature extraction method is proposed in this study. The Chirplet-based approach was used to estimate some obvious harmonics of instantaneous rotating speed and the average value of these components was regarded as the final instantaneous rotating speed to reduce the estimation error. Since the higher order energy operator (HOEO) can not only improve the signal-to-noise ratio and signal-to-interference ratio, but is also easily applied, an adaptive combined HOEO method based on hybrid particle swarm optimizer with sine cosine acceleration coefficients (H-PSO-SCAC) was constructed to enhance the impulse components, and then, the fault features were extracted by the order spectrum analysis. Simulation and experimental results indicate that the proposed algorithm is effective for rolling element bearings’ fault diagnosis under variable speed condition.     

基于Pro/E的发动机曲柄滑块机构的运动仿真分析

阐述了单活塞发动机的工作原理,研究了在Pro/E软件环境中建立曲柄滑块机构模型,并可动态地进行曲柄滑块机构的运动仿真分析.以实例验证了参数化设计的曲柄滑块机构在计算机中虚拟装配完成之后的运动学仿真结果,可以快速完成机构设计的同时还能对所设计结果进行初步检验,节省了传统样机试验所需的时间、人力和财力.     

基于信息熵融合提取特征的发动机气路分析

针对航空发动机多源信息冗余的健康参数估计问题,提出基于信息熵融合的特征提取方法,将其用于涡轴发动机气路分析中。分别采用近似熵和互信息熵2种方法分析不同故障模式下传感器参数,对特征信息进行融合提取,根据2种信息熵不同特点将每种故障模式下传感器参数分成强、弱2类,利用弱特征信号构建虚拟传感器,最后通过简约强特征信息和虚拟传感器信息解决最小二乘支持向量回归机的样本稀疏性问题,实现健康参数蜕化估计。仿真结果表明采用信息熵融合的特征提取方法有效地减少了输入参数维数,简约了特征样本,从而提高了发动机健康估计能力。     

旋转状态下干涉配合应力分析的边界元法

本文对边界元法用于旋转状态下干涉配合的应力分析进行了讨论。根据边界局部坐标与整体坐标间的关系,推导出适用于处理干涉配合中接合面上的联接条件的二维弹性问题的边界积分方程;建立了旋转状态下干涉配合应力分析的边界元方程,并讨论了数值计算的方法。文中给出了一个算例,将边界元解与解析解进行了比较。计算表明,文中的方法对旋转状态下干涉配合的应力分析是可行的,其计算精度令人满意。