基于低摩擦的柴油机节能新方法研究

针对车用柴油机节能问题,提出一种基于低摩擦技术的柴油机综合节能方法。研究柴油机摩擦副低摩擦技术,采用涂层技术与润滑技术减少摩擦副磨损;搭建柴油机节能综合试验台,通过油耗仪和尾气分析仪检测节能减排效果。实验研究表明,采用涂层技术与耐磨润滑油,具有较好的节能效果,实现柴油机的节能,这为车用柴油机的节能减排提供了新的方法与思路。     

Lubricating oil influence on exhaust hydrocarbon emissions from a gasoline fueled engine

Engine exhaust hydrocarbon emissions have been investigated for different lubricating oils, using gasoline as fuel. Six samples of lubricants have been tested: synthetic SAE 5W30 and SAE 5W40, semi-synthetic SAE 15W40 and SAE 20W50, and mineral SAE 15W40 and SAE 20W50. Experiments were carried out in a production engine mounted on a bench test dynamometer, varying engine load and speed in the range from 1500 to 6000 rev/min. The results demonstrate the influence of lubricant viscosity and base oil on hydrocarbon emissions. The synthetic oils showed the lowest hydrocarbon emission levels, especially in the low engine speed range.     

Development of friction force model for mineral oil basestock containing palm olein and antiwear additive

Palm oil is also another choice of vegetable that is being eyed as a potential vegetable oil in the lubricating area. This paper presents a study of the development of a fiction force model for mineral oil basestock containing palm olein, and antiwear amine phosphate as additive, tested on a four-ball tribotester. The model is developed using terms of wear load, speed and operating time. These variables were investigated using the design of experiments and utilization of the response surface methodology (RSM). Moreover, the effect of palm oil on wear scars of material tested was also discussed. This paper shows palm olein itself indeed is a good antiwear lubricant compared to mineral oil basestock (SN500), but the use of additives shows an increase in better lubrication as smaller wear scars are found out from using palm olein in the test runs.     

Effect of palm oil methyl ester and its emulsions on lubricant degradation and engine component wear

This paper presents the results of experimental work carried out to evaluate the effect of palm oil methyl ester also known as palm oil diesel (POD) and its emulsions, as alternative fuels, on unmodified indirect‐injection diesel engine wear and lubricant oil deterioration compared with ordinary diesel (OD). A constant 2500 rpm engine setting at half throttle was maintained throughout the wear debris and lubricant oil analysis period for 20 h for each fuel system. Samples of lubricant oil were collected through a one‐way valve connected to the crankcase sump at intervals of 4 h. The first sample was collected immediately after the engine had warmed up. The same lubricating oil, a conventional SAE 30, was used for all experiments. A multi‐element oil analyser was used to measure metal wear debris and lubricating oil additive depletion for the used lubricating oil. An ISL automatic houillon viscometer (ASTM D 445) and potentiometric titration (ASTM D 2896) were used to measure the viscosity and total base number, respectively. The lubricant oil analysis results for POD, OD, and their emulsions containing 10% water by volume were compared. Very promising results were obtained. The accumulation of metal wear debris in crankcase oil samples was lower with POD and its emulsion compared with the OD fuel. The addition of 10% water (by volume) to POD showed a promising tendency for wear resistance.     

以汽油和甲醇为燃料时小型二冲程发动机摩擦特性比较

采用往复振动机模拟小型二冲程发动机运转工况，实验研究汽油和甲醇为燃料时发动机气缸和活塞环间的摩擦特性，并比较分别使用润滑油新油、润滑油老化油、润滑油新油和老化油的混合油作为润滑油时气缸和活塞环间的摩擦特性。结果表明，以甲醇为燃料时的摩擦因数和磨损量均小于以汽油为燃料时的摩擦因数和磨损量，特别是使用添加了润滑油新油的燃料时的摩擦因数和磨损量最小。通过黏度和热重（TG）分析，探讨甲醇燃料改善气缸和活塞环间的摩擦特性的原因，结果表明，甲醇燃料具有较高的黏度和较低的摩擦因数，因而以甲醇为燃料时可以降低磨损     

Friction and Wear Phenomena of Vegetable Oil–Based Lubricants with Additives at Severe Sliding Wear Conditions

The tribological responses of palm oil and soybean oil, combined with two commercial antiwear additives (zinc dialkyl dithiophosphate and boron compound), were investigated at a lubricant temperature of 100°C and under severe contact conditions in a reciprocating sliding contact. The friction coefficient of palm oil with zinc dialkyl dithiophosphate was closest to the commercial mineral engine oil, with a 2% difference. The soybean oil with zinc dialkyl dithiophosphate produced a 57% improvement in wear resistance compared to its pure oil state. The existence of boron nitride in vegetable oils was only responsive in reduction of wear rather than friction. The response of commercial antiwear additives with vegetable oils showed a potential for the future improvement in the performance of vegetable oils.     

Tribological Effects of Vegetable Oil as Alternative Lubricant: A Pin-on-Disk Tribometer and Wear Study

The investigation of lubricated friction and wear is an extended study. The aim of this study is to investigate the friction and wear characteristics of double fractionated palm oil (DFPO) as a biolubricant using a pin-on-disk tribotester under loads of 50 and 100 N with rotating speeds of 1, 2, 3, 4, and 5 ms^?1 in a 1-h operation time. In this study, hydraulic oil and engine oil (SAE 40) were used as reference base lubricants. The experiment was conducted using aluminum pins and an SKD 11(alloy tool steel) disc lubricated with test lubricants. To investigate the wear and friction behavior, images of the worn surface were taken by optical microscopy. From the experimental results, the coefficient of friction (COF) rose when the sliding speed and load were high. In addition, the wear rate for a load of 100 N for all lubricants was almost always higher compared to lubricant with a load of 50 N. The results of this experiment reveal that the palm oil lubricant can be used as a lubricating oil, which would help to reduce the global demand for petroleum-based lubricants substantially.     

纳米级铜粉改善润滑油抗磨性能的研究

在ＭＨＫ－５００型环块摩擦磨损试验机上,研究了纳米级金属铜粉（直径在１０￣５０ｎｍ）加入到矿物油中的润滑性能。结果表明,在低中滴动速度下（滑动速度分别为１．２８５ｍ／ｓ和２．５７ｍ／ｓ）,加有纳米级铜粉的润滑油表现出优良的抗磨性能。通过ＳＥＭ扫描电镜对磨痕形貌进行分析,提出了低滑动速度和高滑动速度下,纳米级铜粉分别以“垫片”和“滚珠”形态参与润滑。     

Effect of lubricants on the friction and wear of Al2O3 against gray cast iron

The tribological behavior of ceramic Al₂O₃ coupled with gray cast iron (PHT) with different lubricants was investigated using a ring-on-block wear tester. In the wear test, air, distilled water, emulsion and oil were used as lubricants respectively in order to check the lubricating effectiveness of lubricants and the friction mechanism of solid graphite in the cast iron. Wear testing of 0.8% C steel (T8) sliding with Al₂O₃ was also carried out to compare with the test using gray cast iron. From these data the tribological behavior of graphite in the iron can be evaluated. The results show that the friction and wear of tested couples are decreased using different lubricants in the following order: air, distilled water, emulsion and oil. When lubricating with air and water, graphite in the iron as solid lubricant can decrease the friction and wear of the couples. However, when lubricating with emulsion and oil, graphite does not show the advantage of decreasing friction and wear.     

A New Tribological Approach for Lubricated Sliding Contact of Pitted Metallic Curvature Cup

Interest in the development and application of plant-based lubricants for medical use is increasing. This study investigates palm oil lubricants as environmentally friendly and renewable resources to optimize the motion in an ergonomic simulated metal hip prosthesis with modification to the acetabular cup surface. Although metal hip replacements are extensively used, minimizing metal-on-metal friction and wear using safe lubricants requires further investigation. The main physical properties of palm kernel oil and palm fatty acid distillate are considered. The viscosity, wear scar, and coefficient of friction are compared to hyaluronic acid. A modified pin-on-disc tribometer simulates friction and wear on a 28-mm-diameter acetabular cup and microscopy image analysis is used to examine the wear scar. The physical properties of palm oil derivatives reduce friction and wear. In brief, the most significant results of this study include the effect of lubricant and number of pits on wear and friction coefficient. The contribution of this research work is to maintain stability and increase the lifetime of ergonomic metal hip implants.     

固体润滑涂层在干摩擦及有油条件下的摩擦磨损性能

采用MRH-3环块磨损试验机对FM-510二硫化钼润滑涂层在于摩擦及有油条件下进行了摩擦磨损性能的考察和评价,评价结果表明：该涂层在干摩擦条件下具有低的摩擦系数、高的承载能力和长的耐磨寿命,摩擦系数随负荷增高而降低,随速度提高也降低。摩擦偶对双面涂膜比单面涂膜有更长的耐磨寿命,速度低时涂层的磨耗小,寿命长,可满足特定条件下的干摩擦工作要求,在有油润滑条件下二硫化钼基的FM-510润滑涂层可显减轻对偶磨损程度,摩擦系数比单独使用油润滑时大大降低。在难以形成连续的流体润滑薄膜,亦即不能形成流体动力润滑的情况下。摩擦偶对涂敷固体润滑涂层是解决其润滑问题的有效方案。     

Friction and wear bench tests of different engine liner surface finishes

Six different bore finishes of combustion engines were bench-tested against PVD-coated rings. Ring and liner specimens were removed from actual Heavy-Duty Diesel engine. The test was conducted in a CETR UMT-2 reciprocating tester. Current bore honings, e.g. slide honing, as well as recently developed structured laser were tested.For friction bench tests, the specimens were tested at different reciprocating speeds and loads. When lubricant condition approached the boundary regime (speed/load tending to zero), most of the finishes showed the usual boundary friction coefficient 0.11. When the conditions tended to the hydrodynamic regime, the specimen removed from the non-laser region of the laser-structured finish showed a remarkably low friction coefficient, followed by the laser-structured ones.For wear bench tests, the lubricant was doped with hard particles, and higher load and speed were used to accelerate the wear rate. Wear tests ran for 4 h and, as expected, friction coefficient reduced during the wear test due to break-in. In general, friction during the wear test followed the friction test ranking. The remarkable exception was the UV laser finish, which initially presented one of the highest coefficient and after 0.5 h of testing turned to be one of the lowest. Liner and ring wear was measured post-test by profilemeter. In general, the smoother surfaces presented lower ring and bore wear.Greenwood asperity parameters and Patir and Cheng flow factors were calculated from two measured surfaces. A computer model was applied to calculate the oil film thickness and friction for the different speed and load conditions. The calculated friction results showed good adherence to the measured data.     

The influence of engine oil on diesel exhaust emissions

Increasingly stringent emission legislation, together with the requirements for improved diesel engine performance, such as fuel economy, friction reduction, and extended drain intervals, have led to attention being focused on engine oil quality. The use of low‐friction engine oils can improve engine fuel efficiency and lead to a significant reduction of gaseous emissions. Therefore, engine oil is of importance when considering engine design parameters. This paper describes a study of the contribution of engine oil to diesel exhaust emissions. The investigations have shown that diesel engine particulate emissions as well as hydrocarbons and NO_X emissions depend on the lubricant oil properties, in particular on the sulphur content, volatility, and metal content.     

空间用合成碳氢润滑油的长寿命润滑特性分析

为评估空间润滑油在空间环境下的摩擦磨损和长寿命润滑性能,以空间碳氢润滑油RP4752为研究对象,分别采用真空螺旋摩擦试验机(SOT)和滑动摩擦试验机测试润滑油的名义润滑寿命、磨斑直径和滑动摩擦因数,结合扫描电子显微镜和X射线能量色散谱仪进行微观分析。结果表明：RP4752润滑油在真空环境下滑动摩擦因数较小,耐磨寿命较长,具有良好的真空边界润滑性能,试验前后润滑油的红外透过率在14~16.25 μm波段无明显变化。在真空寿命验证试验中,两台采用RP4752润滑油润滑轴承的扫描电机旋转圈数达3.02×10⁸,满足运动机构8年在轨运行寿命的需求。此寿命试验结果与SOT试验的润滑油名义寿命每微克1 615圈可形成比对关系,为其他空间运动机构润滑油的选用及长寿命润滑设计提供试验依据。     

Viscosity and working efficiency analysis of soybean oil based bio-lubricants

This article presents significant data about viscosity and working efficiency analysis for developing the soybean oil based bio-lubricants. A suitable viscosity or viscosity index (VI) plays a very important role in a lubricant, which can avoid collision and rubbing between components of mechanical devices in work as well as optimize working efficiency of a machine. In general, low friction between devices can increase working efficiency of a machine, but low viscosity of a lubricant will easily cause collision and rubbing between components of mechanical devices in work. A too viscous lubricant also requires a large amount of energy to move, but a too thin lubricant will easily cause rubbed devices and increased friction. To replace the mineral oils and syntholubes, the soybean oil is recently become one of the most actively studied oils due to its eco-friendly organic property and lower cost. This work used mixtures of the original soybean oil, the epoxidized soybean oil, and the hydrogenated soybean oil as the base oils. Applications are focused on developing engine bio-lubricants. The results show that the epoxidized soybean oil has extremely large viscosity in comparison with the engine lubricants as well as the original soybean oil, whereas the hydrogenated soybean oil is clearly opposite. This viscosity analysis offers good informations to fit viscosity of the engine lubricants by mixing the three soybean oils as base oils.     

有机钼复合润滑剂在高温微动和滑动条件下的摩擦磨损行为

以矿物基650SN油作为基础油,采用复配技术制备了有机钼复合润滑剂。利用SRV微动磨损试验机和T-11滑动磨损试验机考察了该复合剂的高温摩擦学行为,采用扫描电子显微镜和X射线光电子能谱仪对其润滑下的磨痕表面形貌和表面膜的元素组成进行了分析,探讨了复合剂的减摩润滑机制。结果表明:有机钼复合剂具有良好的高温微动和滑动摩擦学行为,与基础油相比,复合剂能够使钢-钢摩擦副在高温微动和滑动过程中的摩擦因数降低28%和43%,抵抗微动和滑动磨损的能力分别提高53%和54%。这是由于有机钼复合剂通过分解、吸附和摩擦化学反应,在摩擦副金属表面形成了含磷酸盐的沉积膜和含FeS、MoS2的化学反应膜共同组成的复合边界润滑膜,从而表现出优良的减摩润滑效果。     

Sliding wear response of a cast iron under varying test environments and traversal speed and pressure conditions

This study pertains to the examination of sliding wear behaviour of a gray cast iron over a range of sliding speeds and applied pressures in dry and (oil and oil plus graphite) lubricated conditions. Wear properties characterized were wear rate and frictional heating. The cast iron revealed various forms and sizes of graphite particles in a matrix of pearlite and limited quantity of free ferrite. Different solidification patterns, as controlled by the chemical composition and/or carbon equivalent of the alloy and rate of cooling, were thought to be responsible for the varying morphology of the graphite phase formed in the material matrix. Occasional decohesion of graphite at ferrite/graphite interfacial regions was also observed.The wear rate of the cast iron increased with the speed and pressure of sliding due to increasing severity of wear condition. The specimens tended to lose proper contact with the disc at larger pressures when slid dry. This was attributed to severe cracking tendency of the material. On the contrary, specimen seizure was noticed in the oil and oil plus graphite lubricated conditions; the seizure resistance (pressure) decreased with sliding speed in presence of the lubricants. The wear rate versus pressure plots attained different slopes, i.e. the rate of increase in wear rate with pressure, depending on the test environment. One slope and inappreciable effect of pressure on wear rate were noticed due to substantial cracking tendency of the cast iron when tested in dry condition. In the oil lubricated condition also, virtually one slope was observed but it was higher than that in dry condition indicating greater sensitivity of wear rate towards the applied pressure. Also, the samples attained lower wear rate in oil than in dry condition in view of suppressed cracking tendency causing more stable lubricating film formation in presence of the oil lubricant. Addition of graphite particles to the oil lubricant caused a further reduction in wear rate because of the enhanced possibility of a more stable lubricant film formation due to smearing of the graphite particles. In this case, the slope of the wear rate versus pressure plots was the least in the intermediate range of pressures irrespective of the sliding speed owing to more stable lubricating film formation.A higher rate of temperature increase with test duration (intermediate sliding distance) in the beginning was attributed to the abrasive action of the hard debris generated through the fragmentation of the initially contacting asperities. A subsequently observed lower rate of increase at longer durations could be owing to the occurrence of mild wear condition in view of less stressing of the contacting asperities and increased stability of the lubricant film formed. Increase in the rate of frictional heating at still longer durations resulted from destabilization of the lubricating film.Frictional heating increased with applied pressure and sliding speed in view of increasing severity of wear condition. The rate of increase in frictional heating was low initially up to a specific pressure followed by a higher rate of increase at still larger pressures when the tests were conducted in oil plus graphite at both the sliding speeds and in the oil lubricant at the lower speed. A constant (high) rate of increase in frictional heating with pressure was noticed in the dry condition at both the sliding speeds and in the oil lubricant at the higher speed. Low rate of frictional heating with pressure was attributed to the occurrence of mild wear condition while a higher rate of frictional heating with pressure resulted from the occurrence of severe wear condition. As far as the influence of test environment on frictional heating is concerned, least frictional heat was generated in the oil plus graphite lubricant mixture while the maximum was noticed in dry condition, intermediate response of the samples being observed in oil. Formation of more stable lubricating film was thought to be responsible for lower frictional heating in the lubricated conditions; the presence of graphite in the oil lubricant increased the extent of lubricating film formation and stability of the film so formed.The wear response of the samples has been explained in terms of cracking tendency and lubricating effects of graphite, predominance of the counteracting effects of the two parameters over each other, and lubricating film formation by the external oil (plus graphite) lubricant on the sliding surfaces in specific test conditions. Characterization of wear surfaces, subsurface regions and debris particles of the material enabled to further substantiate the observed wear performance of the samples.     

On the behaviour of an oil lubricated fretting contact

Although many engineering situations involving fretting damage are lubricated, comparatively little has been reported on this aspect of fretting wear. The viscosity of the lubricating oil and its boundary layer performance are expected to influence fretting behaviour, in addition to the normal fretting parameters, such as stroke and contact force.

This paper examines the effect of lubrication regime, oil viscosity and stroke on the behaviour of a ball-against-flat specimen arrangement. Ball and flat specimens were both manufactured from a bearing steel (SUJ2). Polybutane oils, without additives, covering a range of viscosities from 1 to 10 000 cSt, and fretting strokes up to 35 μm were investigated. The lubricating oil was added to the fretting interface after 0, 3 and 2000 fretting cycles had been completed. Lubrication regime, oil viscosity and stroke were all found to affect fretting behaviour in terms of both coefficient of friction (or traction coefficient) and wear. For strokes less than 9 μm, i.e. for conditions approaching almost complete ‘stick’, coefficient of friction values under oil lubrication were well in excess of double those observed without it. These high values suggest that the oil was unable to penetrate into the fretting contact region, but did maintain a shield around it, so that metal-on-metal contact was maintained under oxygen deprived conditions. The lowest values of steady state coefficient of friction (≈ 0.2) were observed when oil lubrication was applied after 2000 cycles had been completed, indicating that surface roughening and the presence of oxide films and oxidised debris assisted penetration of the lubricant into the fretting contact zone.     

Tribological Characteristics of Calophyllum inophyllum–Based TMP (Trimethylolpropane) Ester as Energy-Saving and Biodegradable Lubricant

The purpose of this research is an experimental study of Calophyllum inophyllum (CI)-based trymethylolpropane (TMP) ester as an energy-saving and biodegradable lubricant and compare it with commercial lubricant and paraffin mineral oil using a four-ball tribometer. CI-based TMP ester is a renewable lubricant that is nonedible, biodegradable, and nontoxic and has net zero greenhouse gases. The TMP ester was produced from CI oil, which has high lubricity properties such as higher density, higher viscosity at both 40°C and 100°C and higher viscosity index (VI). Experiments were conducted during 3,600 s with constant load of 40 kg and constant sliding speed of 1,200 rpm at temperatures of 50, 60, 70, 80, 90, and 100°C for all three types of lubricant. The results show that CI TMP ester had the lowest coefficient of friction (COF) as well as lower consumption of energy at all test temperatures, but the worn surface roughness average (R_a) and wear scar diameter were higher compared to paraffin mineral oil and commercial lubricant. Before 80°C, CI TMP ester actually has a higher flash temperature parameter (FTP) than paraffin mineral oil and as the temperature increases, the FTP of TMP ester decreases. The worn surfaces of the stationary balls were analyzed by scanning electron microscopy (SEM) and results show that CI TMP ester has the highest wear compared to paraffin mineral oil and lowest wear compared to commercial lubricant. However, CI TMP ester is environmentally desired, competitive to commercial lubricant, and its use should be encouraged.     

The lubricated wear of ceramics : Part II: The wear and friction of silicon nitride and steel in the presence of mineral oil or an ester based lubricant

The friction and wear characteristics of combinations of silicon nitride, alumina and AISI 52100 steel in the presence of mineral oil containing anti-wear, dispersant and detergent additives have been investigated in a tri-pin-on-disc machine. The tests were carried out at a nominal temperature of 100°C for a range of sliding speeds, loads and total sliding distances. In Part II of this two-part paper a comparison will be made between the tribological performance of these sliding pairs of materials in mineral oil and ester based lubricant environments. The results of the investigation showed that the alumina performed relatively poorly under these test conditions, whereas silicon nitride showed good potential as an improved wear resisting material compared with 52100 steel. Wear factors of the order of 10⁻¹⁰ mm³/Nm were deduced for the alumina, while values as low as 10⁻¹¹ mm³/Nm were typical of the silicon nitride sliding against 52100 steel discs. The alumina pins wore by a process of brittle fracture at the surface, whereas the silicon nitride pins wore primarily by a tribochemical polishing mechanism. The rate of tribo-chemical wear was found to be proportional to the nominal contact area.