采用复合陶瓷薄膜强化喷油器偶件

1 问题的提出喷油器质量好坏是影响柴油机热力状态的主要因素之一.喷油器工作不良造成柴油机在运用中排气总管、排气支管发红破损,增压器转子固死,严重影响机车的正常运用.从各机务段内燃机车喷油器的使用与统计来看,其偶件故障最为突出,而偶件故障最根本的问题是60°锥角面磨损严重超限所引起的.     

东风4型内燃机车联合调节器故障扳手

1 概述 昂昂溪机务段现有东风4型内燃机车100台,每年因联合调节器故障发生多起事故.事故发生后,一是等待事故救援;二是乘务员冒飞车危险,用管钳子人为扳动柴油机供油拉杆,使柴油机继续供油使故障机车维持回段.这种方法极易扩大事故,造成严重经济损失.所以联合调节器运行途中发生故障后的处理,成为迫切需要解决的问题.     

东风4D型机车柴油机气缸盖裂损引起高温膨胀水箱溢水故障诊断

1前言 东风4D型机车是我国铁路为提速而开发的新型大功率内燃机车,自1997年开始配属各提速机务段.该机车投入运用一段时间后,柴油机部分气缸盖底板在φ273mm止口处开始产生裂纹,并随着运用公里增加,部分气缸盖裂纹扩展到与气缸盖冷却水腔贯通.当柴油机工作时,高温、高压燃气通过裂缝窜人冷却水系统,造成高温膨胀水箱溢水.机务段检修部门处理这种故障的常规作法是采用关缸来确定,或者吊换整台柴油机气缸盖进行探伤检查.前者故障排查效率低,有时仍解决不了问题;后者扩大修程处理,费时费力.笔者在现场经过多次实践,摸索出利用红外线测温仪测量气缸盖出水支管外侧表面温度来诊断裂穿气缸盖,它是一种非常准确、方便、快捷判断故障的方法.表1所列为成功诊断的事例.     

柴油机停机原因分析及防止措施

1 故障现象2001年9月2日,蚌埠机务段东风4B型2245号机车牵引列车进站,主手柄回0位,柴油机突然停机.起机无效,在附挂机车的推行下回段,险些造成机破.回段后,检查发现:柴油机最低稳定转速止钉从根部切断.更换后,起机成功.     

DF4型机车典型故障的判定及处理

1问题的提出 叶柏寿机务段是一个由蒸汽向内燃转型刚刚过渡完毕的机务段,共配属内燃机车64台,其中:DF4B型机车56台;DF4B改进型机车2台;DF5型机车6台.追溯转型过渡阶段的1998～2002年的4年中,机车先后发生柴油机的主机油泵、活塞连杆组、主轴瓦、连杆瓦和机车动轮不转等故障共计21件.其中17件造成机车在牵引途中发生机破事故,占故障总数的81.0%,严重干扰了正常的运输秩序.     

加装DLS继电装置防止内燃机车自然停机故障

1任务来源内燃机车自然停机故障,是指机车柴油机在运用过程中通过非正常程序及保护装置动作(包括差示动作、超速保护等)而使柴油机瞬间停机的故障。机车发生故障后,乘务员如果不能正确地判断柴油机自然停机的原因,盲目靠短接油压继电器维持运行,很容易造成柴油机曲轴烧损报废、机体主轴承孔严重变形的事故,更重要的会使监控装置断电,影响列车的安全、正点运行,干扰正常的运输生产秩序。同时,运行途中频繁的起动柴油机对机车蓄电池和乘务员的工作情绪都会造成不利影响。2004年1~3月间,经统计的机统-6记录中济南西机务段淄博折返段(原淄博机务…     

东风4型内燃机车柴油机曲轴箱超夺的原因及防治

列举了灵丘机务段2000年1月至2000年8月实际发生的柴油机曲轴箱超压故障现象,指出其月平均发生率为1.5件.分析了故障原因并提出了防治措施.     

东风4型内燃机车蓄电池常见故障原因及改进措施

1 概述蓄电池是内燃机车的重要部件,承担着柴油机起动用电和一部分机车部件用电的供应.昂昂溪机务段现有机车100台,过去蓄电池质量一直不够稳定.蓄电池冻结、过放、极板脱落、连线烧损、亏电等故障频繁发生,从而导致蓄电池报废数量剧增,仅1998、1999年间就有300多节报废,严重影响机车质量,造成经济损失20多万元.     

DF12型机车柴油机季节性停机故障解决措施

1 问题的提出 日照港铁运公司机务段现有内燃机车10台,其中DF12型机车8台,是港口铁路运输生产的主力车型.在日常检修过程中发现,在夏季高温气候下,机车柴油机经常发生季节性停机故障.     

一例柴油-发电机组振动、游车故障的查找及分析

1 前言 武昌南机务段DF8型0035号机车担当武汉地区枢纽的货运列车牵引任务.该车在4小1辅后的第28天(中修后总走行212425km),因柴油-发电机组振动,从江岸西附挂回段,在未查出故障真实原因又投入运用7天后,柴油-发电机组振动严重并伴有负载游车故障.为防止柴油机大破损,乘务员途中请求救援,造成机破.严重干扰了地区枢纽运输秩序.     

Diesel–diesel and diesel–ethanol drop collisions

In view of the possible occurrence of unlike drop collisions in a diesel spray due to the increasing application of alcoholic fuels as supplementary fuels in diesel engines, collisions of a diesel drop with either a diesel drop or an ethanol drop were studied. Diesel drop collision results do not display appreciable difference, within experimental errors, from those of tetradecane drops except for very small Weber numbers. The collision of an ethanol drop with a diesel drop, when compared to binary diesel drop collisions, exhibits higher tendency towards reflex separation for near head-on collisions and lower tendency towards stretching separation for medium to high impact parameter collisions. These distinctions come from the spreading of ethanol over the diesel drop due to their difference in surface tension.     

柴油机压力波检测仪在内燃机车上的应用

简述了压力波检测仪在机车检修中的具体作用,详尽分析了对典型故障的处理办法,提出仪器在实际运用过程中应该注意的几个具体问题.     

Triglycerides-based diesel fuels

Efforts are under way in many countries, including India, to search for suitable alternative diesel fuels that are environment friendly. The need to search for these fuels arises mainly from the standpoint of preserving the global environment and the concern about long-term supplies of conventional hydrocarbon-based diesel fuels. Among the different possible sources, diesel fuels derived from triglycerides (vegetable oils/animal fats) present a promising alternative to substitute diesel fuels. Although triglycerides can fuel diesel engines, their high viscosities, low volatilities and poor cold flow properties have led to the investigation of various derivatives. Fatty acid methyl esters, known as biodiesel, derived from triglycerides by transesterification with methanol have received the most attention. The main advantages of using biodiesel are its renewability, better-quality exhaust gas emissions, its biodegradability and given that all the organic carbon present is photosynthetic in origin, it does not contribute to a rise in the level of carbon dioxide in the atmosphere and consequently to the greenhouse effect.     

Combustion characteristics of a direct-injection diesel engine fueled with Fischer-Tropsch diesel

Fischer-Tropsch (F-T) diesel fuel is characterized by a high cetane number, a near-zero sulphur content and a very low aromatic level. On the basis of the recorded incylinder pressures and injector needle lifts, the combustion characteristics of an unmodified single-cylinder direct-injection diesel engine operating on F-T diesel fuel are analyzed and compared with those of conventional diesel fuel operation. The results show that F-T diesel fuel exhibits a slightly longer injection delay and injection duration, an average of 18.7% shorter ignition delay, and a comparable total combustion duration when compared to those of conventional diesel fuel. Meanwhile, F-T diesel fuel displays an average of 26.8% lower peak value of premixed burning rate and a higher peak value of diffusive burning rate. In addition, the F-T diesel engine has a slightly lower peak combustion pressure, a far lower rate of pressure rise, and a lower mechanical load and combustion noise than the conventional diesel engine. The brake specific fuel consumption is lower and the effective thermal efficiency is higher for F-T diesel fuel operation. Translated from Journal of Xi’an Jiaotong University, 2006, 40(1): 5–9 [译自: 西安交通大学学报]     

GKD2型调车内燃机车

GKD2型调车内燃机车是为满足工矿企业及铁路部门对调车内燃机车的需求而研制的,是东风11型、东风8B型内燃机车的系列产品.本文介绍了该机车的总体布置、主要技术参数、主要部件的特点和预期的牵引性能.     

Hydrogen assisted diesel combustion

Hydrogen assisted diesel combustion was investigated on a DDC/VM Motori 2.5L, 4-cylinder, turbocharged, common rail, direct injection light-duty diesel engine, with a focus on exhaust emissions. Hydrogen was substituted for diesel fuel on an energy basis of 0%, 2.5%, 5%, 7.5%, 10% and 15% by aspiration of hydrogen into the engine's intake air. Four speed and load conditions were investigated (1800 rpm at 25% and 75% of maximum output and 3600 rpm at 25% and 75% of maximum output). A significant retarding of injection timing by the engine's electronic control unit (ECU) was observed during the increased aspiration of hydrogen. The retarding of injection timing resulted in significant NO_X emission reductions, however, the same emission reductions were achieved without aspirated hydrogen by manually retarding the injection timing. Subsequently, hydrogen assisted diesel combustion was examined, with the pilot and main injection timings locked, to study the effects caused directly by hydrogen addition. Hydrogen assisted diesel combustion resulted in a modest increase of NO_X emissions and a shift in NO/NO₂ ratio in which NO emissions decreased and NO₂ emissions increased, with NO₂ becoming the dominant NO_X component in some combustion modes. Computational fluid dynamics analysis (CFD) of the hydrogen assisted diesel combustion process captured this trend and reproduced the experimentally observed trends of hydrogen's effect on the composition of NO_X for some operating conditions. A model that explicitly accounts for turbulence–chemistry interactions using a transported probability density function (PDF) method was better able to reproduce the experimental trends, compared to a model that ignores the influence of turbulent fluctuations on mean chemical production rates, although the importance of the fluctuations is not as strong as has been reported in some other recent modeling studies. The CFD results confirm that temperature changes alone are not sufficient to explain the observed reduction in NO and increase in NO₂ with increasing H₂. The CFD results are consistent with the hypothesis that in-cylinder HO₂ levels increase with increasing hydrogen, and that the increase in HO₂ enhances the conversion of NO to NO₂. Increased aspiration of hydrogen resulted in PM, and HC emissions which were combustion mode dependent. Predominantly, CO and CO₂ decreased with the increase of hydrogen. The aspiration of hydrogen into the engine modestly decreased fuel economy due to reduced volumetric efficiency from the displacement of air in the cylinder by hydrogen.     

燃油催化微粒捕集器对柴油机性能影响的研究

研究了一种燃油催化剂再生微粒捕集器的微粒捕集与再生特性。通过柴油机台架试验分析了该微粒捕集器对国产CA6DL1-28型柴油机的动力性、燃油经济性和排放性能的影响。试验结果表明,该微粒捕集器具有同类其他产品无法比拟的良好特性,同时也为其对其他国产发动机的适应性研究提供了依据。     

Dual-fuelling of an industrial indirect injection diesel engine by diesel and liquid petroleum gas

For partial substitution of conventional diesel fuel with liquified-petroleum gas (LPG) fuel, in an indirect-injection, (IDI) diesel engine, the so-called ‘mixed diesel gas’ approach has been applied. For this purpose, a carburetted LPG fuel system has been designed and fitted on the inlet manifold of the engine. Extensive performance tests have been carried out at full load conditions of both the pure diesel and diesel-LPG engines. The results show that, at the rated speed, and at equal power of both engines, increasing the LPG proportion in the dual fuel decreases specific fuel consumption, exhaust gas temperature and black smoke but increase pollutants such as UHC and CO, cylinder peak pressure and the rate of pressure rise.     

Performance and emission characteristics of a diesel engine using isobutanol–diesel fuel blends

The aim of this study is to investigate the suitability of isobutanol–diesel fuel blends as an alternative fuel for the diesel engine, and experimentally determine their effects on the engine performance and exhaust emissions, namely break power, break specific fuel consumption (BSFC), break thermal efficiency (BTE) and emissions of CO, HC and NO_x. For this purpose, four different isobutanol–diesel fuel blends containing 5, 10, 15 and 20% isobutanol were prepared in volume basis and tested in a naturally aspirated four stroke direct injection diesel engine at full -load conditions at the speeds between 1200 and 2800 rpm with intervals of 200 rpm. The results obtained with the blends were compared to those with the diesel fuel as baseline. The test results indicate that the break power slightly decreases with the blends containing up to 10% isobutanol, whereas it significantly decreases with the blends containing 15 and 20% isobutanol. There is an increase in the BSFC in proportional to the isobutanol content in the blends. Although diesel fuel yields the highest BTE, the blend containing 10% isobutanol results in a slight improvement in BTE at high engine speeds. The results also reveal that, compared to diesel fuel, CO and NO_x emissions decrease with the use of the blends, while HC emissions increase considerably.     

Polycyclic aromatic hydrocarbons in flames, in diesel fuels, and in diesel emissions

Numerous chemical analyses of gaseous and particulate samples from laboratory flames provide a library of data on the polycyclic aromatic hydrocarbon (PAH) species found in diverse flame types burning fuels consisting of pure gaseous hydrocarbons. The diesel fuels utilized by the more complex combustion in compression ignition engines are composed of thousands of hydrocarbon species. Mass spectrometry by the laser microprobe and gas chromatography were used in a complementary manner to distinguish the PAHs originating in the fuel from those produced by engine combustion. The C_xH_y PAH products of premixed and diffusion flame processes, which also occur in the unsteady diesel combustion, range in mass from 128 u (two rings, x=10, y=8) to beyond 350 u (eight rings, x=28, y=14). Graphs of the number of hydrogen atoms y vs the number of carbon atoms x for the species found by many investigators of laboratory flames show these pyrogenic PAHs to lie on or near the staircase curve that describes the most stable, pericondensed, benzenoid PAHs. In contrast, samples of diesel fuels from the United Kingdom and the United States contain petrogenic alkyl-PAHs with high hydrogen contents. Samples of diesel particulate emissions typical of the 1990s from two different sources display the full mass range of PAHs from 128 to 350 u, including both the benzenoid PAHs and the alkyl-PAHs. Thus diesel emissions, in general, may contain petrogenic fuel components ranging up to 206 u and also the combustion-generated four- to seven-ring species in the 228 to 302 u mass range that have greater carcinogenic potency. The absence of petrogenic components larger than 206 u facilitates their detection and delineation from pyrogenic PAHs by methods of chemical analysis.