Influence of pilot injection on combustion characteristics and emissions in a DI diesel engine fueled with diesel and DME

This work experimentally investigates how the dwell time between pilot injection and main injection influences combustion and emissions characteristics (NOx, CO, THC and smoke) in a single-cylinder DI diesel engine. The experiments were conducted using two fuel injection systems according to the fuel type, diesel or dimethyl ether (DME), due to the different fuel characteristics. The injection strategy is accomplished by varying the dwell time (10°CA, 16°CA and 22°CA) between injections at five main injection timings (?4°CA aTDC, ?2°CA aTDC, 0°CA aTDC, 2°CA aTDC and 4°CA aTDC). Results from pilot-main injection conditions are compared with those shown in single injection conditions to better demonstrate the potential of pilot injection. It was found that pilot injection is highly effective for lowering heat-release rates with smooth pressure traces regardless of the fuel type. Pilot injection also offers high potential to maintain or increase the BMEP; even the combustion-timing is retarded to suppress the NOx emission formation. Overall, NOx emission formation was suppressed more by the combustion phasing retard effect, and not the pilot injection effect considered in this study. Comparison of the emissions for different fuel types shows that CO and HC emissions have low values below 100 ppm for DME operation in both single injection and pilot-main injection. However, NOx emission is slightly higher in the earlier main injection timings (?4°CA aTDC, ?2°CA aTDC) than diesel injections. Pilot injection was found to be more effective with DME for reducing the amount of NOx emission with combustion retardation, which indicates a level of NOx emission similar to that of diesel. Although the diesel pilot-main injection conditions show higher smoke emission than single-injection condition, DME has little smoke emission regardless of injection strategy.     

Comprehensive experimental study on the effect of biodiesel/diesel blended fuel on common-rail di diesel engine technology

This research work aims to study the aspects of using biodiesel or FAME as a component blended in diesel fuel for common-rail DI engine technology. The specific engine experiments were designed for LD commercial engine [Toyota 2KD-FTV] to understand engine combustion process, engine performance and thermal efficiency when applying FAME blended fuel. In addition, the exhaust emission in HD diesel engine [HINO J08E] was evaluated by standard HD engine emission ESC and ELR test cycles. Furthermore, the severe 400-hour of HD engine durability tests for determining the limitation on using FAME blended fuel, have been conducted with B0, B10, B20 and B50. The result shows that using of FAME blended fuel in the HD common-rail DI engine, can be applied with some guidelines experimentally discovered by this research such as filter plugging that may occur when the content of biodiesel is up to 20 % or higher, and the critical fuel injector surface polishing wear, can be observed from B50 sample. In general, the higher biodiesel content will contribute to lower power output as well, thus too high biodiesel content will cause low engine power output.     

现代汽车柴油机的电控喷射系统

就柴油机电控系统中的燃油喷射系统的系统组成,及其对循环供(喷)油量、供(喷)油正时、供(喷)油速率和供(喷)油规律和喷油压力的控制进行了论述,并就现代柴油机电控燃油喷射系统的发展前景提出了看法.     

柴油机共轨式燃料喷射系统

介绍了三种柴油机共轨式燃油喷射系统。说明了共轨式燃油喷射系统的优点和开发应用中要解决的几个问题。     

Development of new 4-valve/cylinder small DI diesel engine

Nitrous oxide (NO_x) and the particulate matter contained in the exhaust given off by diesel powered vehicles have been identified as elements responsible for polluting the atmosphere. As such, these emissions have been the targets of increasingly strict emission control regulations. Plans are underway to introduce regulations that are even stricter some time early in the next century. The advanced thermal efficiency offered by diesel engines is a feature clearly desired for its potential contribution toward energy conservation and the reduction of global warming. Research and development on the highly thermal-efficient direct-injection diesel engine are progressing at a rapid pace in Europe where introduction of a carbon dioxide tax is under consideration.     

车用大功率柴油机电控喷油系统的开发研究

以车用 6V1 5 0柴油机原有的机械控制喷油系统为基础 ,开发电控喷油系统 ,实现了对喷油量的电子控制。采用高速开关型数字电磁阀作为电液执行器的电液转换元件 ;采用 MC68HC1 1 E2单片机作为电控单元的核心 ;在喷油泵供油齿杆位置闭环控制的基础上 ,实现柴油机转速闭环控制 ;开发了实验监控系统 ,以满足电控喷油系统与柴油机匹配的需要。进行了电控喷油系统与6V1 5 0柴油机的匹配实验 ,取得了较好的效果     

Development of engine control using the in-cylinder pressure signal in a high speed direct injection diesel engine

Emission regulations are becoming more stringent and remain a principal issue for vehicle manufacturers. Many engine subsystems and control technologies have been introduced to meet the demands of these regulations. For diesel engines, combustion control is one of the most effective approaches for reducing not only engine exhaust emissions but also cylinder-by-cylinder variation. However, the high cost of pressure sensors and the complex engine head design for additional equipment present difficulties for manufacturers. In this paper, cylinder pressure-based engine control logic is introduced for a multi-cylinder high speed direct injection (HSDI) diesel engine. The time for 50% of the mass fraction to be burned (MFB50) and the IMEP are valuable for determining the combustion status. These two in-cylinder quantities are measured and applied to the engine control logic. Fuel injection timing is controlled to adjust the operating MFB50 to the target MFB50 using PID control logic, and the fuel injection quantity is controlled to adjust the measured IMEP to the desired IMEP. The control logic is demonstrated at steady state and during transient conditions and is applied to an NEDC mode test.     

Comparison of two injection systems in an HSDI diesel engine using split injection and different injector nozzles

The demand for reduced pollutant emissions has motivated various technological advances in passenger car diesel engines. This paper presents a study comparing two fuel injection systems and analyzing their combustion noise and pollutant emissions. The abilities of different injection strategies to meet strict regulations were evaluated. The difficult task of maintaining a constant specific fuel consumption while trying to reduce pollutant emissions was the aim of this study. The engine being tested was a 0.287-liter single-cylinder engine equipped with a common-rail injection system. A solenoid and a piezoelectric injector were tested in the engine. The engine was operated under low load conditions using two injection events, high EGR rates, no swirl, three injection pressures and eight different dwell times. Four injector nozzles with approximately the same fuel injection rate were tested using the solenoid injection system (10 and 12 orifice configuration) and piezoelectric system (6 and 12 orifice design). The injection system had a significant influence on pollutant emissions and combustion noise. The piezoelectric injector presented the best characteristics for future studies since it allows for shorter injection durations and greater precision, which means smaller fuel mass deliveries with faster responses.     

车用柴油机喷油系统的使用维护与故障判断

本文介绍了车用柴油机与汽油机的不同工作特点和燃油系统;柴油机喷油系统主要部件结构型式和使用维护与调整;柴油机燃油系统可能发生的故障及其原因和排除方法。     

高压喷油对柴油机燃烧的影响

在直喷式柴油机上,提高喷油压力能改善其混合气形成过程和燃烧。但应该查明,转速范围在2000r/min内,使用常规喷油系统(泵-管-喷嘴),使喷油压力约至200MPa,喷油持续期为22℃A,每循环喷油量为530mm~3是否可行;进而考虑到指示效率和燃料的不完全混合,这种改善的可能性是否存在。在上述基础上则应确定喷油压力的一个合理的上限值。 通过模拟计算来辅助确定高压喷油系统的设计参数时,必须对诸如柴油机燃油中的音速、高压油管中的衰减、柱塞偶件上的泄漏以及喷油泵的总形等基础数据予以确定及评估。 通过高压力的喷油能改善指示效率,减少黑烟排放,并在调整其余的混合气形成参数时降低氮氧化物的排放。由此得出16OMPa是喷油压力合理的上限值,是油耗、烟度和氮氧化物之间的合理折衷。     

对二甲基醚发动机燃油系的构想

从环保角度来看，二甲基醚（ＤＭＥ）被认为是柴油的理想替代燃料，但由于ＤＭＥ的物理性质类似液化石油（ＬＰＧ），常温下为气体状态，加压液化后，粘性低，压缩性随温度变化很大，这些决定了对燃油系统设计提出的要求很高，燃料泄漏与润滑性是首先要考虑的问题。本文介绍了几种燃油系的构想，如共轨系统、泵一管一嘴系统。为ＤＭＥ发动机燃油系统设计得提供一些有益的参考。     

Numerical study of the early injection parameters on wall wetting characteristics of an HCCI diesel engine using early injection strategy

Wall wetting in the early injection period has been proved to be unavoidable in the HCCI (Homogeneous charge compression ignition) diesel engine using early injection strategy, which directly affects in-cylinder fuel-air mixture formation. In this study, the effects of the early injection parameters (injection timing, injection angle and injection pressure) on wall wetting characteristics of an HCCI diesel engine using early injection strategy have been numerically investigated. The variations of maximum wall film mass, evaporated wall film mass and residual wall film mass have been summarized. The concept of MHI (Mixture Homogenous Index) is introduced to evaluate the homogeneity of fuel-air mixture in the wall wetting region. In additions, the effects of the early injection parameters on the HC (Hydrocarbon Compounds) and CO (Carbon Monoxide) emissions have also been discussed. Results showed that in order to decrease the HC and CO emission caused by wall wetting as low as possible, it was better to increase the injection pressure and to advance the injection timing. The most effective method was to narrow the injection angle, In addition, the impingement target should be considered for choosing the injection timing and injection angle, and the impingement target of the piston bowl lip was recommended due to the enhancement of the atomization and the higher surface temperature.     

电子喷射技术在现代柴油发电机组中的应用

简术了柴油机的电喷技术，介绍了电喷柴油发电机组的特点。     

汽车用高速柴油机分配泵电控系统的研究

针对ＶＥ型分配式喷油泵进行了电子控制的研究，研制成功了分配泵电控系统；开发了新的油量控制机构，在定时控制机构中，采用高速开关阀作为电液转换元件；系统地设计也电控单元的硬件系统，开发了具有层次体系的模块化结构控制软件；台架试验结果表明；分配泵电控实现了预期的控制功能、改善了柴油机的性能。     

MTU新型柴油机的电控系统

MTU新型柴油机采用了高度集成机体、分流式冷却系统、三层壁排气管以及新型的电控系统，其中电子燃油喷射系统的应用使柴油机的经济性得到了提高，排放得到了优化；而电子管理系统使柴油机的许多功能得以完善，整体性能得以提高。重点阐述三种新系列柴油机的电控系统的工作原理及特点。     

Effect of injection condition and swirl on D.I. diesel combustion in a transparent engine system

The objective of this work was to investigate the effects of injection conditions and swirl on D.I. diesel combustion using a transparent engine system. The test engine is equipped with a common rail injection system to control injection conditions and to obtain split injection characteristics. A combustion analysis and steady flow test were conducted to measure the heat release rate due to cylinder pressure and the swirl ratio. In addition, spray and diffusion flame images were obtained using a high speed camera. The LII & LIS methods were also used to obtain 2-D soot and droplet distributions. High injection pressure was found to shorten ignition delay, as well as to enhance peak pressure. The results also revealed that the heat release rate in the premixed combustion region was markedly reduced through the use of pilot injection, while the soot distribution and the heat release rate in the diffusion combustion region were increased. The swirl effect was found to shorten ignition delay at certain injection timings, and to enhance the heat release rate in all experimental conditions.