A methodology for combustion detection in diesel engines through in-cylinder pressure derivative signal

In-cylinder pressure measurement has historically been used for off-line combustion diagnosis, but online application for real-time combustion control has become of great interest. This work considers low computing-cost methods for analysing the instant variation of the chamber pressure, directly obtained from the electric signal provided by a traditional piezoelectric sensor. Presented methods are based on the detection of sudden changes in the chamber pressure, which are amplified by the pressure derivative, and which are due to thermodynamic phenomena within the cylinder. Signal analysis tools both in time and in time-frequency domains are used for detecting the start of combustion, the end of combustion and the heat release peak. Results are compared with classical thermodynamic analysis and validated in several turbocharged diesel engines.     

Digital signal processing of in-cylinder pressure for combustion diagnosis of internal combustion engines

In-cylinder pressure analysis is a key tool for engine research and diagnosis; however, it normally requires to process the experimental signal for providing valuable information. Usual four-step data processing consists on level correction, angle referencing, cycle averaging, and filtering. Concerning the last two issues, ad-hoc methods and experience-based algorithms are mostly used, and there is not a consensus in the scientific community about the optimal way to proceed. This paper presents a step-by-step approach to optimise the signal processing both for offline and online applications based on the characteristics of the signal.     

柴油机机油压力过低故障诊断

柴油发动机主要零件是靠机油润滑,如果机油压力过低,相对运动的零件之间难以形成润滑油膜而造成干摩擦,继续使用发动机会酿成烧瓦、拉缸等重大事故。当柴油机机油压力低于0．2MPa时,应立即停机,检查原因。     

Estimation of optimum number of cycles for combustion analysis using measured in-cylinder pressure signal in conventional CI engine

Analysis of measured in-cylinder pressure data provides various parameters that characterize engine combustion process. Advanced engine control technologies use cylinder pressure based combustion parameters for closed loop control. Four step signal processing (i) absolute pressure correction, (ii) crank angle position referencing, (iii) cycle averaging and (iv) filtering is typically applied to get sufficiently accurate cylinder pressure data for an engine cycle. This paper focuses on cycle averaging and filtering of in-cylinder pressure signal from a conventional compression ignition (CI) engine. Experiments are conducted at different engine load and compression ratios at 1500 rpm. The in-cylinder pressure trace of 2500 consecutive engine cycles is recorded and analyzed. Effect of in-cylinder pressure signal noise and cyclic variation on combustion analysis is investigated. A method based on standard deviation of pressure and pressure rise rate is used to find sufficient minimum number of engine cycles to be recorded for averaging to get reasonably accurate pressure data independent of cyclic variability.     

Multivariate statistical analysis strategy for multiple misfire detection in internal combustion engines

This paper proposes a multivariate statistical analysis approach to processing the instantaneous engine speed signal for the purpose of locating multiple misfire events in internal combustion engines. The state of each cylinder is described with a characteristic vector extracted from the instantaneous engine speed signal following a three-step procedure. These characteristic vectors are considered as the values of various procedure parameters of an engine cycle. Therefore, determination of occurrence of misfire events and identification of misfiring cylinders can be accomplished by a principal component analysis (PCA) based pattern recognition methodology. The proposed algorithm can be implemented easily in practice because the threshold can be defined adaptively without the information of operating conditions. Besides, the effect of torsional vibration on the engine speed waveform is interpreted as the presence of super powerful cylinder, which is also isolated by the algorithm. The misfiring cylinder and the super powerful cylinder are often adjacent in the firing sequence, thus missing detections and false alarms can be avoided effectively by checking the relationship between the cylinders.     

A tribological investigation of lubricant effects on bearing friction and fuel economy for passenger car engines and heavy duty diesel engines

Rising fuel costs and the need to conserve fossil fuel have led to increased interest in the role of lubricants in improving fuel economy. Crankshaft bearings can account for up to 40% of engine friction. Lubricant formulations can provide a beneficial reduction in engine friction, thus improving fuel economy. A unique journal bearing test rig has been developed to evaluate lubricants under transient and steady‐state conditions for passenger car engines and heavy duty diesel engines. The rig can measure bearing friction over a wide temperature, speed and load range. The rig uses production components and can be operated so as to produce the bearing pressures, lambda ratio and shear rates experienced by lubricants in fired engines. The properties of a range of lubricants of varying viscometrics, including Newtonian, non‐Newtonian and fully formulated oils have been evaluated. Significant differences due to formulation have been observed. The results of the study have been compared to fuel economy data generated from fired engines with the same lubricants as those tested in the journal bearing rig. Copyright © 2006 John Wiley & Sons, Ltd.     

WD615系列柴油机采标及思考

1　潍柴产品采标情况简介积极采用国际标准和国外先进标准是我国的一项重大技术经济政策 ,是推动企业技术进步 ,提高产品质量的一项重要措施 ,在我国即将加入 WTO之际 ,搞好采标工作 ,对于消除技术壁垒 ,加快与国际惯例接轨 ,增强企业竞争力尤显重要。潍柴多年来一直重视采标工作。 1 992年以来 ,先后有 6 1 6 0 A,495等五大系列 1 4个变型产品获得采标证书 ,尤其是近几年 ,随着市场经济的不断深入 ,争创“明星企业”,“名牌产品”的需要 ,企业加大了采标工作的力度 ,1 997年 ,有 84GF3,1 2 0 GF4,1 6 0 GF1 ,2 0 0 GF1 0 2柴油发电机…     

Reply to comment by Maurice et al. in response to “Bragg’s Law Diffraction Simulations for Electron Backscatter Diffraction Analysis”

A reply to Maurice et al.'s comment on "Bragg's Law Diffraction Simulations for Electron Backscatter Diffraction" is presented. A new method for microscope geometry calibration is briefly presented. Also, evidence that simple diffraction simulations can be profitable tools for absolute elastic strain measurements in crystalline materials is reiterated.     

基于L-T的联合算法在光纤法珀纳米压力传感器脉压检测信号中的应用

研究了一种改进的去噪方法及其在脉冲拍频信号去噪中的应用。该算法结合了局部均值分解(Local mean decomposition,LMD)和时频峰值滤波(Time-frequency peak filtering,TFPF)的优点,称为L-T算法。TFPF作为一种经典的时频滤波方法,较长的窗长可以在保留信号幅值的前提下有效抑制随机噪声,而较短的窗长则导致信号幅值严重衰减。因此,为了保持有效信号幅度、抑制随机噪声,对LMD和TFPF进行了改进。首先利用LMD将原始信号分解为无级生存(Progression-free survival,PFS),然后计算各乘积函数均值的标准误差,将许多PFSs分为有用分量、混合分量和噪声分量。其次,将短窗TFPF用于有用分量去噪,长窗TFPF用于混合分量去噪,得到重构后的信号。最后,将该算法用于F-P压力传感器的降噪。实验结果表明,与传统小波去噪算法相比,L-T算法去噪效果更优。     

A comparison of different methods for fuel delivery unevenness detection in Diesel engines

Conventional misfire diagnosis techniques are based on the analysis of the instantaneous engine speed. Although they have proved their efficiency in some operating conditions and for the detection of total misfires, their performance could be insufficient in a near future. This paper presents a comparative study of different alternative detection principles for the detection of slight unevenness between cylinders in the injection process for a turbocharged Diesel engine. The selected techniques are the instantaneous exhaust manifold pressure, the instantaneous turbocharger speed and the mean temperature at the exhaust cylinder ports. All alternative techniques show improved performance and linearity compared to the conventional one, particularly at high engine speed and low load. All these techniques are compared with the conventional approach and main advantages and disadvantages are discussed.     

A study on effects of recirculated exhaust gas upon wear of cylinder liner and piston in diesel engines

The effects of recirculated exhaust gas on the wear of cylinder liner and piston were experimentally investigated by a two-cylinder, four cycle, indirect injection diesel engine operating at 75% load and 1600 rpm. For the purpose of comparison between the wear rates of the two cylinders with and without EGR, the recirculated exhaust gas was sucked into one of two cylinders after the soot in exhaust emissions was removed by an intentionally designed cylinder-type scrubber equipped with 6 water injectors (A water injector has 144 nozzles of mm diameter), while only the fresh air was inhaled into the other cylinder. These experiments were carried out with the fuel injection timing fixed at 15.3° BTDC. It was found that the mean wear rate of cylinder liner with EGR was greater in the measurement positions of the second half than those of the first half, that the mean wear rate without EGR was almost uniform regardless of measurement positions, and that the wear rate of piston skirt with EGR increased a little bit, but the piston head diameter increased, rather than decreased, owing to soot adhesion and erosion wear, and especially larger with EGR.     

激光透射式粉尘仪的微弱信号处理研究

为实现在线监测粉尘浓度,设计了一个激光在线粉尘检测仪.在一个典型的烟尘排放连续监测(CEMS)系统中,激光粉尘检测距离要求达到15m以上,然而半导体激光器的输出光功率在20 mW以下.为了从强噪声背景中提取极其微弱的反射光信号,设计了一种数字平均器以提取“nW”级别的微弱反射光信号.对原型机在不同测量距离和消光比条件下...     

A model and the methodology for determining wear particle generation rate and filter efficiency in a diesel engine using ferrography

A mathematical model was developed that describes the wear particle concentration as a function of time in a diesel engine. This model contains engine and lubrication system parameters that determine the concentration of wear particles in the engine sump. These variables are the oil system volume, oil flow rate, particle generation rate, filtering efficiency and the initial particle concentration. The model was employed to study the wear particle concentrations in the sump and the mass of particles in the filter for the Cummins VT-903 diesel engine. In addition, the model was used to develop a testing methodology for determining wear particle generation rates and filter efficiencies from used oil analysis. This testing methodology uses ferrography together with computer programs to yield accurate statistical information on the data as curve fitted to the model. The test set-up incorporated a remote-controlled sampling system that enabled the accurate and periodic taking of oil samples over an engine test approximately 5 h in duration.

Results of this research indicate that equilibrium wear particle concentrations increase with an increase in engine speed and load. The wear particle generation rate and filter efficiency as determined by the test methodology were found to decrease with an increase in engine speed and load. After oil and filter changes, the wear particle generation rate and filter efficiency continually increased with cumulative engine time up to approximately 11 h. The test methods used to obtain the results above were found to be repeatable to within ±15% and could conceivably be employed to determine wear parameters on other diesel engines as well as the effects that other engine variables such as lubricants, oil temperature, coolant temperature and engine components have on the wear parameters.