Engine friction lubricant sensitivities: A comparison of modern diesel and gasoline engines

Engine friction models have been developed that take account of the variations in lubricants with temperature, shear rate, and pressure. These models have been used to study the lubricant sensitivities of modern diesel and gasoline engines. Total engine friction losses for a Perkins Phaser four‐cylinder, 4.0 l, turbocharged, inter‐cooled diesel engine, operating at 1300 rpm, with an SAE 15W‐40 lubricant, were estimated at approximately 2 kW, with the piston assembly contributing 46%, the bearings 49%, and the valve train 5%. Total engine friction losses for a Mercedes Benz M111 2.0 l gasoline engine (used in CEC sludge and fuel economy engine tests) operating at 2500 rpm, and medium load, for an SAE 15W‐40 lubricant, were estimated at 1.5 kW, with the piston assembly contributing 42%, the bearings 39%, and the valve train 19%.     

Numerical evaluation of the potential for fuel economy improvement due to boundary friction reduction within heavy-duty diesel engines

Advanced surface treatments have been developed by a number of research institutes as an approach to reduce friction at sliding interfaces. Laboratory tests have shown that some of these surface treatments can result in boundary friction reductions approaching an order of magnitude [1], [2] and [3]. While there are many potential applications for such surface treatments, friction reduction in internal combustion engines is of particular interest due to the apparent fuel savings potential. Ricardo, Inc. has performed simulations to estimate potential fuel economy improvements due to the application of such treatments at key interfaces within engines typical of those used in large trucks. The results show that fuel economy improvements in excess of 4% can be achieved from combined application of a surface treatment and reduction in lubricant viscosity, if the surfaces can be protected against wear.     

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.     

Investigation of the scuffing characteristics of candidate materials for heavy duty diesel fuel injectors

The objective of this study is to characterize and understand the evolutionary processes that produce changes in the friction and surface damage in materials for possible use as heavy duty diesel fuel injector plungers. This work has involved the development of test methods to impart reciprocating motion to various metals, ceramics, and coated specimens in the presence of diesel fuel-like fluids. Commercial and candidate plunger materials, including 52100 steel, zirconia, cermets (TiC in Ni₃Al matrix), and TiN coatings, were evaluated on a crossed-cylinders-like scuffing test we call the ‘pin-on-twin’ geometry. Contacts were lubricated by on-highway #2 diesel and Jet A aviation fuels. Using friction-based criteria, the material ranking was in good agreement with field experience with actual injectors from the diesel engine industry. Zirconia and cermets exhibited promising scuffing resistance in both fuels. Scuffing generally became more severe in the Jet A fuel. Experimental results indicated that smoother surfaces that are required to sustain higher injection pressures could be more vulnerable to scuffing due to their thinner lubricant films. Material transfer was the major scuffing mechanism of zirconia, cermets, and TiN coatings against steel. Micro-scratches were also observed on the matrix material of cermets.     

Lubricant viscosity and viscosity improver additive effects on diesel fuel economy

This work verifies the impact of lubricant viscosity and viscosity improver additives on diesel fuel economy. Eight lubricants were tested in a single-cylinder, four-stroke, direct injection diesel engine mounted on a dynamometer, under different load and speed conditions. Engine friction power was also investigated through Willans’ line. The results demonstrate that fuel economy obtained from multigrade viscosity oils is higher than that obtained from monograde viscosity oils. A linear relationship was obtained between the high temperature high shear viscosity and specific fuel consumption. The lubricant which provided lower fuel consumption also required lower friction power.     

Tribological aspects of by-pass oil filters on gasoline passenger car engines

Contaminants in passenger car engines are physically separated from lubricating oil by full flow oil filters. The additional cleaning in by-pass filters should allow oil drain intervals to be extended or to operate engines without oil change and reduce engine wear noticeably, as claimed by some by-pass filter manufacturers. To establish whether the claim is mere conjecture or if the addition of by-pass filters into the oil circuits of passenger car gasoline engines are indeed of real benefit with respect to engine and lubricant performance, a research project was initiated by the UBA on behalf of the German environment ministry. Special attention had to be paid to the influence on oil contamination, variation in viscosity, detergency, dispersancy, fuel and oil consumption, engine wear and overall reliability and durability. Some highlights of the total programme are presented in this paper.     

高速铁路客车振动特性试验研究

针对车辆线路跟踪试验所测得的各主要部件的三向振动加速度值,通过时域统计和频域分析方法提取数据的主要特征,探究轮轨激扰产生的振动能量从轴箱到构架、构架再到车体的传递关系。研究结果表明,由于车辆的一系悬挂系统刚度和阻尼比较大,其对于高频垂向振动有明显的隔振减震作用,但对于低频振动的隔振效果有限。二系悬挂系统对于低频振动则具有很好的隔振减震作用,很好地弥补了一系悬挂系统的不足之处,传递至车体的振动能量和幅值都明显成数量级衰减了。     

A rig test to measure friction and wear of heavy duty diesel engine piston rings and cylinder liners using realistic lubricants

Laboratory tests to evaluate piston ring and cylinder liner materials for their friction and wear behavior in realistic engine oils are described to support the development of new standard test methods. A ring segment was tested against a flat specimen of gray cast iron typical of cylinder liners. A wide range of lubricants including Jet A aviation fuel, mineral oil, and a new and engine-aged, fully formulated 15W40 heavy duty oil were used to evaluate the sensitivity of the tests to lubricant condition. Test temperatures ranged from 25 to 100 °C. A stepped load procedure was used to evaluate friction behavior using a run-in ring segment. At 100 °C, all lubricants showed boundary lubrication behavior, however, differences among the lubricants could be detected. Wear tests were carried out at 240 N for 6 h at 100 °C with new ring segments. The extent of wear was measured by weight loss, wear volume and wear depth using a geometric model that takes into account compound curvatures before and after testing. Wear volume by weight loss compared well with profilometry. Laboratory test results are compared to engine wear rates.     

Numerical investigation of the combined effects of slip and texture on tribological performance of bearing

Slider bearings are used in many applications. An increase in the load support may allow for saving of energy. In this work, in order to enhance the load support and decrease the friction force, a combined textured surface bearing using boundary slip is discussed. A modified Reynolds equation with slip is adopted. With the main goal of evaluating the effects of slip and texture, a parametric analysis is performed. For the given operating conditions, texturing features as well as slip pattern are analysed in detail. The numerical analysis is undertaken under the condition of different gap ratio values and the slip-textured area. The results show that combined techniques of slip and texture have a significant effect on the improvement of the tribological performance of bearing, that is, a high load support but low friction force. The gap ratio of the bearing is shown to have a significant effect on the lubrication behaviour. It is found that even with a smallest gap ratio (parallel gap), a high load support can be produced. However, it is also shown that the gap ratio appears to contribute to the generated friction force and the volume flow rate more than the boundary slip. Further analysis indicates that the optimum slip-text zones for certain gap ratio are highlighted. These findings may provide references for designing hydrodynamic-textured slider bearing considering boundary slip.     

Measurement and modeling of crank train friction in light-duty diesel engines

Journal of Mechanical Science and Technology - In this study, we present measurements and calculations of friction energy loss in the crank train of a light-duty vehicle diesel engine. The main...     

3D heat transfer,lubrication and friction coupled study for piston ring-liner on diesel engines

The piston ring and liner of internal combustion engines are generally used under increasingly harsh conditions. To investigate the mechanisms affecting the work ineffective, the coupled heat transfer, lubrication and friction model between the piston ring and liner is proposed by coupling the gas, piston set-liner, lubrication film and coolant. In this model, the temperature variation of lubricant, the gas blowby, the surface roughness, the rupture position and the non-axial symmetry of oil film are considered. The coupled heat transfer, lubrication and friction simulation is carried out for 6110 diesel engine, and the temperature fields of piston set-liner along with the corresponding lubrication and friction curves are obtained. The simulated results are verified by comparing with the temperature experiment of piston.

     

Research on effects of key influencing factors upon fuel injection characteristics of the combination electronic unit pump for diesel engines

A numerical model of the combination electronic unit pump (CEUP) fuel injection system was developed in AMESim environment. The effects of five key influencing factors, including cam profile velocity, plunger diameter, length of high pressure fuel pipe, inner diameter of high pressure fuel pipe and nozzle flow rate on injection characteristic parameters, were analyzed by using the developed numerical model. On the basis, a correlation analysis between the influencing factors and injection characteristics was performed by using the design of experiments (DoE) method, and the influences of these factors were quantized accordingly. Relevant results show that both the single influencing factor and the interaction among these factors correlates with the injection characteristics, and the correlation represents a complex law with the cam rotational speed. The effect of plunger diameter on the injection pressure, cycle fuel injection quantity and injection duration is the most obvious, especially at a cam rotational speed of 500 r/min and the correlation coefficient is up to 0.82. The length of high-pressure pipe (HP pipe) has the most obvious influence on the coefficient of fuel feeding at cam rotational speed of 500 r/min and 800 r/min, and the correlation coefficient is negative. Overall, the independent influence of the factors is more significant than the combined influence of various factors. The CEUP fuel injection system is a complicated multi-input multi-output (MIMO) nonlinear system in fact.     

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.

     

大轴重铁路货车轴承选型与设计

根据重载货运需求,借鉴既有铁路货车轴承成功使用的经验,进行了重载铁路货车轴承选型、设计及维护的研究,通过优化设计、仿真分析及综合试验等手段,实现了重载铁路货车轴承的合理设计,满足了重载铁路货车的使用要求。     

A study of the tribological behaviour of piston ring/cylinder liner interaction in diesel engines using acoustic emission

The novel use of non-intrusive acoustic emission (AE) measurements to provide information pertaining to the interaction between piston rings and cylinder liners in a range of diesel engines is investigated in this paper. In doing so, this technique is shown to offer a new method of investigation into this important interface in engine operation.AE generated during normal engine operation is known to consist of contributions from a number of different sources such as injector and valve activity. A recent finding has been the identification of AE signals associated with the ring/liner interface which presents the opportunity for in-service monitoring. This work discusses the possible AE source mechanisms, such as asperity contact, lubricant flow and/or blowby, through reference to a number of tests on motored and in-service small HSDI diesel engines and large, 2-stroke, marine diesel engines. The influence of various factors such as engine speed, load and lubrication is considered.     

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.     

An investigation on the performance of a Brayton cycle waste heat recovery system for turbocharged diesel engines

A Brayton cycle waste heat recovery (WHR) system for turbocharged diesel engines was proposed and the performance of a diesel engine integrated with the proposed system was investigated. The waste heat recovery system is integrated with the turbocharging system of diesel engines, using the turbocharger compressor as the Brayton cycle compressor. The engine cycle simulation code GT-Suite 7.0 was used to investigate the performance of a diesel engine integrated with the WHR system. A Brayton cycle turbine was designed and its performance was simulated with a through-flow model. The turbocharging system of the original engine was modified and the energy flow distribution between the diesel cycle and the Brayton cycle was optimized. Results show that the fuel economy of the diesel engine can be improved by 2.6% at high engine speed and 4.6% at low engine speed under engine full load operating conditions when equipped with the Brayton cycle WHR system. The influence of turbocharger parameters on the WHR engine performance was invesgated.     

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.     

基于PLC的柴油机重油动态乳化过程控制系统

根据船舶柴油机重油动态乳化过程的特点,设计了将PLC控制的方法应用于重油动态乳化过程的控制系统,介绍了系统的工作流程、功能特点以及系统硬件和软件设计,并给出了部分实验核心程序。实验结果表明,该系统对掺水率的控制精度可达1%以上,燃油消耗率平均降低7.8%。     

柴油发动机寿命实时预测系统的设计与实现

通过三通道传感器设计实现柴油发动机缸压力、机油压力和喷油压力数据的在线同步采集,并导入柴油发动机寿命预测数学模型,实现不解体的情况下动态测算柴油发动机的剩余寿命,判断发动机工作状态及何时需要进行发动机检修.实验表明在同一地区车辆行驶里程越大,预测提前量也越大;西藏地区的总体预测提前量大于广西地区的预测提前量.