Adaptation of a zero-dimensional cylinder pressure model for diesel engines using the crankshaft rotational speed

Tighter emission regulations are driving the development of advanced engine control strategies relying on feedback information from the combustion chamber. In this context, it is especially seeked for alternatives to expensive in-cylinder pressure sensors. The present study addresses these issues by pursuing a simulation-based approach. It focuses on the extension of an empirical, zero-dimensional cylinder pressure model using the engine speed signal in order to detect cylinder-wise variations in combustion. As a special feature, only information available from the standard sensor configuration are utilized. Within the study, different methods for the model-based reconstruction of the combustion pressure including nonlinear Kalman filtering are compared. As a result, the accuracy of the cylinder pressure model can be enhanced. At the same time, the inevitable limitations of the proposed methods are outlined.     

Tribotechnical and mechanical properties of Ti-Al-N nanocomposite coatings deposited by the ion-plasma method

The possibility of formation of nanocrystalline Ti-Al-N coatings using the method of ion-plasma deposition is demonstrated. The mechanical and tribotechnical characteristics of the coatings in comparison with TiN coating are studied. Ti-Al-N nanocomposite coatings possess high hardness (35 GPa) and higher wear resistance and lower wear capacity as compared to TiN coating. For a grain size of 12–15 nm the nanostructural Ti-Al-N coating has the following elemental composition: Ti ≈ 60 at %, N ≈ 30 at %, Al ≈ 10 at %. The phase composition of the coating represents the solid solution (Ti, Al)N. For this elemental and phase composition and nanograin size maximal hardness and elasticity modulus of the coating are found.     

Model-based diagnosis of large diesel engines based on angular speed variations of the crankshaft

This work aims at monitoring large diesel engines by analyzing the crankshaft angular speed variations. It focuses on a powerful 20-cylinder diesel engine with crankshaft natural frequencies within the operating speed range. First, the angular speed variations are modeled at the crankshaft free end. This includes modeling both the crankshaft dynamical behavior and the excitation torques. As the engine is very large, the first crankshaft torsional modes are in the low frequency range. A model with the assumption of a flexible crankshaft is required. The excitation torques depend on the in-cylinder pressure curve. The latter is modeled with a phenomenological model. Mechanical and combustion parameters of the model are optimized with the help of actual data. Then, an automated diagnosis based on an artificially intelligent system is proposed. Neural networks are used for pattern recognition of the angular speed waveforms in normal and faulty conditions. Reference patterns required in the training phase are computed with the model, calibrated using a small number of actual measurements. Promising results are obtained. An experimental fuel leakage fault is successfully diagnosed, including detection and localization of the faulty cylinder, as well as the approximation of the fault severity.     

柴油机曲轴的再制造尺寸修复研究

修理尺寸法是以机械加工为主要手段的一种零部件修复方法.通过两种方法确定修复尺寸,对曲轴损伤部位进行适当的机械加工,通过尺寸的改变来恢复其正确的几何形状、精度或配合关系,而继续使用.     

Evaluation of tribological properties of bearing materials for marine diesel engines utilizing acoustic emission technique

Acoustic Emission (AE) technique, which has detection capability for minute failures, has been tried to monitor the condition of a plain bearing under the laboratory conditions. In this paper, the bearing materials for marine diesel engines - tin alloy as known as “white metal”, aluminum alloy of 40% tin mass and aluminum alloy 40% tin mass with resin overlay - were tested using a sleeve-to-plate tribo-tester. The frictional force and back temperature were measured as well as the AE signals. The possibility of AE technique to monitor the bearing condition was also assessed by evaluating tribological properties under different operating conditions such as start-stop simulating the crankshaft turning during engine assembly and seizure tests. These results indicate that AE is useful for monitoring the lubricated condition of the sliding surfaces and evaluating tribological properties of the bearing.     

船用柴油机的大型曲轴机械加工工艺浅析

曲轴是活塞式发动机的主要零部件之一,加工工艺复杂、要求高.船用柴油机的大型曲轴在尺寸和重量上都比普通曲轴大上很多,结合其它曲轴的加工工艺,深入分析船用柴油机的大型曲轴机械加工工艺,并对曲轴机加工发展方向进行了初步探讨.     

运用APDL的柴油机曲轴可靠性分析

采用APDL技术完成曲轴的整体三维参数化建模,并将其结构分析能力与PDS模块的统计分析能力相结合,根据有限元分析技术和可靠性的基本原理,采用蒙特卡罗有限元法实现可靠性分析.以4110型柴油机曲轴为例,将参数化设计引入到有限元结构分析中,实现结构参数快速调整,自动生成分析模型并完成结构分析、可靠性分析过程,详尽叙述了实现曲轴可靠性分析的流程.根据分析结果得到设计变量与目标变量的灵敏度关系,同时给出危险部位的最大应力概率分布函数及目标变量的主要影响因素,为结构可靠性优化设计提供有用数据.     

Systematic evaluation of the reliability of marine diesel engines

A systematic model is proposed for evaluating the operational reliability of marine diesel engines. In mathematical terms, the model is based on continuous Markov chains. It permits the estimation of the overall reliability of marine diesel engines and individual subsystems, as well as the probability of effective operation of the diesel engines at any time.     

机车柴油机组合活塞的温度场数值模拟

应用PRO/E软件对复杂的16v280zjA型柴油机活塞建立三维实体模型,确定活塞的换热边界条件,并借助于软件PRO/EMechanica计算出活塞在热载荷作用下的温度场,计算结果与实测结果基本相吻合.明确了活塞在工作过程中活塞关键部位的温度分布状况,对于工程技术人员来说,了解活塞的温度场具体分布,进而可以求得活塞的应力分布、变形分布情况,为进一步改进组合活塞的结构设计具有一定的参考价值.     

A review of condition monitoring and fault diagnosis for diesel engines

Technical advances and environmental legislation in recent years have stimulated the development of a number of techniques for condition monitoring and fault diagnosis (CMFD) in diesel engines. This paper firstly summarises common faults, fault mechanisms and their effect on diesel engine performance. Corresponding measurands are presented. Standard CMFD methods for parameters and CMFD systems for diesel engines are reviewed. Finally, some advanced CMFD techniques, including neural networks and fuzzy logic, which may be more powerful, are discussed.     

The elementary cell in the systemic analysis of frictional-component designs for diesel engines

Systemic analysis of frictional-component designs for diesel engines is considered. The concept of an elementary frictional cell may be used in evaluating the efficiency of such designs.     

基于随机载荷的柴油机曲轴疲劳主动可靠性研究

文中基于复杂条件下的载荷,探讨适用于柴油机曲轴的可靠性研究方法.从可靠度的3个核心问题--基本变量、功能函数和可靠度算法入手,以应力荷载及其作用循环数作为基本随机变量,依据基于韧性的疲劳累积损伤研究结果确定功能函数,通过循环调用所述计算可靠度指标等的方法,可以确定指定寿命任意置信水平下的可靠度.同时利用结构可靠度方法得到的变量分布信息,结合实验数据考察了特定应力水平下疲劳寿命与可靠度之间的关系,计算结果显示可靠性随着寿命要求的提高而降低.     

A study of the fouling characteristics of EGR coolers in diesel engines

Diesel emission regulations have recently become more severe. An important goal in diesel engine research is the development of methods to reduce the emissions of NOx and PM (particulate matter). Cooled EGR (exhaust gas recirculation) system has been widely used to reduce the NOx and PM emissions of light-duty diesel engines. In this study, numerical analyses, rig tests and engine tests were performed to assess how changes in internal shape characteristics can improve the heat exchange efficiencies of EGR coolers. The heat exchange efficiencies of EGR coolers have been numerically and experimentally measured during a fouling process. The results show that the second type of oval EGR cooler tested (oval #2) exhibited better heat exchange efficiency than either the first type of oval EGR cooler was tested (oval #1) or the shell and tube cooler examined. The turbulence generated in exhaust gas flows by the wavy-finned design of the oval EGR coolers facilitated PM desorption that allows these coolers to self-purify. With respect to the two similar oval EGR coolers, the cooler with fin pitch 4 mm has better efficiency than the cooler with fin pitch 6 mm due to differences in the heat transfer areas of these coolers. Both CFD analyses involving extreme conditions of engine operation and engine fouling tests involving conditions experienced during vehicular operation indicate that the two oval coolers differed by less than 4% with respect to both initial heat transfer efficiency and heat transfer efficiency after a 78-hour fouling test.     

Sliding wear behavior of protective coatings for diesel engine components

The use of heat-insulating ceramic coatings on the cylinder walls of diesel engines is currently being considered for certain advanced engine designs. Since a major consideration in such an application is the wear resistance of the coatings, a series of tests has been carried out to determine the sliding wear behavior of several pairs of candidate materials systems, initially at room temperature. The tests were performed using a washer-on-disc specimen configuration and an oscillatory rotation movement to simulate the motion of a piston ring on a cylinder wall. It was determined that each material tested had a different pattern of sliding wear behavior. Impregnation of plasma-sprayed Y₂O₃-ZrO₂ with chromia markedly improved its wear resistance.     

Analysis upon fuel injection quantity variation of common rail system for diesel engines

Fuel injection quantity variation of common rail system has effect on the stability and reliability of diesel engines. For purpose of investigating the influence rule and mechanism of fuel injection quantity variation caused by parameters, taking account of the influence of fuel physical properties on dynamic injection characteristics of the system, a bond graph model of common rail injector has been proposed based on bond graph methodology and the state equations of the system are obtained. Comparisons between calculated fuel injection quantities by the numerical model and experimental measurements at different rail pressures and injection pulse widths indicate that the developed model can reasonably predict the fuel injection quantity characteristic of the system. Fuel injection quantity variation characteristics caused by the parameters of common rail injector have been analyzed in entire operating conditions. The selected parameters are delivery chamber diameter, needle seat semi-angle, needle cone semi-angle, ball valve seat semi-angle, nozzle hole diameter, inlet orifice diameter and outlet orifice diameter. The variation rules of quantitative percentages are obtained by quantitative analysis upon fuel injection quantity variation influential factors. It is concluded that ball valve seat semi-angle, nozzle hole diameter, inlet orifice diameter and outlet orifice diameter have the most significant effect on fuel injection quantity variation, and the followed are delivery chamber diameter and needle seat semi-angle. In addition, needle cone semi-angle also results in the variation of fuel injection quantity, but the effect is insignificant.

     

应用MATLAB设计柴油机七项式动力凸轮型线

基于单质量动力学模型,推导七项式动力凸轮型线的解析式,利用MATLAB语言编制出设计程序,并以具体的某高速柴油机为例,给出对称凸轮型线的设计结果.     

Predicting the oil cooler fan performance of large-sized diesel engines by changing the outlet and torsion angles

This study analyzed how the outlet and torsion angles of an oil cooler fan in large-sized diesel engines affect the performance of the fan using a numerical analysis method. The discharge flow rate, theoretical power, and efficiency were numerically calculated at the variable outlet and torsion angles. Results showed that the discharge flow rate slightly increased with increased outlet angle, leading to increased theoretical power and efficiency. The outlet-side blade also came closer to a vertical position with smaller torsion angle for higher performance of the fan. To verify the numerical analysis results, an experiment was conducted according to AMCA Standard 210–99 and the results were compared. The performance curve of the experimental and numerical analysis results indicated about 3% error.     

Reduction of wear of crankshaft bearings of V-8 engines by compensating the total unbalanced mass of the crank gear mechanism parts

The work presents the theoretical principles of how to compensate the total mass of crank gear parts and to eliminate the auxiliary free total unbalanced moment emerging when reconditioned or improved pistons, connecting rods, piston rings, and conrod liners are installed in V-8 engines. It is achieved by increasing the mass of the counterweights and the distance between the center of gravity and the axis of rotation, by altering the angles of their arrangement, the mass-geometrical parameters, and the design of the sump plugs in the conrod necks, and by creating an engine-plane-directed imbalance correction. These methods enable compensation of the total unbalanced mass in order to eliminate the above-mentioned moment; they make it possible to balance the crankshaft, improve durability, and reduce the vibration and noise of the V-8 engine.     

Analysis of torsional crankshaft oscillations in a diesel engine on the basis of cylinder-block vibration

Torsional crankshaft oscillations in the diesel engine of an automobile are studied experimentally. Their relation to the cylinder-block vibration is considered. It is established that the vibrations appearing not only at the resonant harmonic but at higher frequencies are due to torsional crankshaft oscillations, which produce impacts in the crankshaft’s slip bearings.     

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。