单缸柴油机喷油系统的模拟计算与试验研究

利用AVL-HYDISM模拟软件建立了1105柴油机喷油系统的仿真模型,模拟了此柴油机标定工况下的喷油性能,从高压油管泵端压力以及嘴端压力两方面与试验值进行了比较,同时计算得出了样机燃油喷射规律以及压力室油压.分析了样机不足,通过改进供油凸轮使得燃油喷射压力得到提高.     

Spray characteristics on the electrostatic rotating bell applicator

The current trend in automotive finishing industry is to use more electrostatic rotating bell (ESRB) need space to their higher transfer efficiency. The flow physics related with the transfer efficiency is strongly influenced by operating parameters. In order to improve their high transfer efficiency without compromising the coating quality, a better understanding is necessary to the ESRB application of metallic basecoat painting for the automobile exterior. This paper presents the results from experimental investigation of the ESRB spray to apply water-borne painting. The visualization, the droplet size, and velocity measurements of the spray flow were conducted under the operating conditions such as liquid flow rate, shaping airflow rate, bell rotational speed, and electrostatic voltage setting. The optical techniques used in here were a microscopic and light sheet visualization by a copper vapor laser, and a phase Doppler particle analyzer (PDPA) system. Water was used as paint surrogate for simplicity. The results show that the bell rotating speed is the most important influencing parameter for atomization processes. Liquid flow rate and shaping airflow rate significantly influence the spray structure. Based on the microscopic visualization, the atomization process occurs in ligament breakup mode, which is one of three atomization modes in rotating atomizer. In the spray transport zone, droplets tend to distribute according to size with the larger drops on the outer periphery of spray. In addition, the results of present study provide detailed information on the paint spray structure and transfer processes.     

Spray structures and vaporizing characteristics of a GDI fuel spray

The spray structures and distribution characteristics of liquid and vapor phases in non-evaporating and evaporating Gasoline Direct Injection (GDI) fuel sprays were investigated using Laser Induced Exciplex Fluorescence (LIEF) technique. Dopants were 2% fluorobenzene and 9% DEM A (diethyl-methyl-amine) in 89% solution of hexane by volume. In order to study internal structure of the spray, droplet size and velocity under non-evaporating condition were measured by Phase Doppler Anemometry (PDA). Liquid and vapor phases were visualized at different moments after the start of injection. Experimental results showed that the spray could be divided into two regions by the fluorescence intensity of liquid phase: cone and mixing regions. Moreover, vortex flow of vapor phase was found in the mixing region. About 5μn diameter droplets were mostly distributed in the vortex flow region. Higher concentration of vapor phase due to vaporization of these droplets was distributed in this region. Particularly, higher concentration of vapor phase and lower one were balanced within the measurement area at 2ms after the start of injection.     

Novel application-oriented transient fuel model of a port fuel injection S. I. engine

Most researches on transient fuel control of port fuel injection S.I. engine are carried out from the perspective of advanced mathematical theories. When it comes to practical control, there exist many limitations although they are more intelligent. In order to overcome the fuel wetting effect of PFI engine, the application-oriented transient fuel control is studied by analyzing the key parameters which are closely related with the engine transient characteristics. Both validity and simplicity are taken into consideration. Based on the fuel wall-wetting theory and popular fuel compensation strategy, short-term transient fuel（STF） and long-term transient fuel（LTF）, as well as their individual decay approaches, are introduced. STF is to compensate the drastic fuel film loss caused by sudden throttle change, while the function of LTF is to compensate the fuel film loss by manifold air pressure（p） fluctuation. Each of them has their respective pros and cons. The engine fuel mass and air mass are also calculated for air-fuel ratio（AFR） according to ideal gas state equation and empirical equations. The vehicle acceleration test is designed for model validation. The engine experiences several mild and heavy accelerations corresponding to the gear change during vehicle acceleration. STF and LTF control are triggered reliably. The engine transient fuel control simulation adopts the same inputs as the test to ensure consistency. The logged test data are used to check the model output. The results show that the maximum fuel pulse width（FPW） error reaches 2 ms, and it only occurs under engine heavy acceleration condition. The average FPW error is 0.57 ms. The results of simulation and test are close overall, which indicates the accuracy of steady and transient fuel. The proposed research provides an efficient approach not only suitable for practical engineering application, but also for AFR prediction, fuel consumption calculation, and further studies on emission control.     

Regulation of the crankshaft speed of a diesel engine with a common rail fuel system

A mathematical model is proposed for the regulation of the crankshaft speed of a diesel engine with a Common Rail fuel system by control of the injection time and the load.     

Combustion characteristics of an agricultural diesel engine using biodiesel fuel

Biodiesel has great potential as an alternative fuel for diesel engines that would reduce air pollution. It is a domestically produced, renewable fuel that can be manufactured from fresh or used vegetable oils, or from animal fats. In this study, a biodiesel fuel derived from rice bran oil was tested as an alternative fuel for agricultural diesel engines. The emissions were characterized for both neat and blended biodiesel fuels, and for conventional diesel fuel. Since this biodiesel fuel contained 11% oxygen, it strongly influenced the combustion process. The use of biodiesel fuel resulted in lower carbon monoxide, carbon dioxide, and smoke emissions, without any increase in nitrous oxide emissions. The study demonstrated that biodiesel fuel could be effectively used as a renewable and environmentally innocuous fuel for agricultural diesel engines.     

Dynamic performances analysis and optimization of novel high-speed electromagnetic actuator for electronic fuel injection system of diesel engine

Journal of Mechanical Science and Technology - High-speed electromagnetic actuator (HEA) is the key component of Electronic fuel injection system (EFIS) of diesel engine, its dynamic performances...     

Applying analytical ferrography as a technique to detect failures in Diesel engine fuel injection systems

This work presents the development of a method which analyzes metallic wear debris and contaminants found to be present in fuels used by Diesel engines. The particles have been isolated by following two complementary methods; firstly, a magnetic separation method and then a filtering method using membranes. Particles are subsequently characterized by means of optical and electron microscopy, where it is possible to establish the type and severity of the wear, as well as establishing how the mechanism parts are actually affected by wear. This technique allows a predictive maintenance of the fuel injection systems to be carried out, as it allows for possible breakdowns to be detected prior to a serious failure being produced.     

Diesel engine fuel injection monitoring using acoustic measurements and independent component analysis

Air-borne acoustic based condition monitoring is a promising technique because of its intrusive nature and the rich information contained within the acoustic signals including all sources. However, the back ground noise contamination, interferences and the number of Internal Combustion Engine ICE vibro-acoustic sources preclude the extraction of condition information using this technique. Therefore, lower energy events; such as fuel injection, are buried within higher energy events and/or corrupted by background noise.     

Effects of different piezo-acting mechanism on two-stage fuel injection and CI combustion in a CRDi engine

In this study, the effects of two piezo injectors operated by different mechanisms on multi-injection and Compression ignition (CI) combustion were investigated. High-pressure injectors for CI engines are divided into two categories according to the actuator: Solenoid and piezo injectors. It is commonly known that both injectors have a hydraulic circuit for fuel injection; thus, the performance of the injector is highly dependent on not only hydraulic characteristics such as volume of internal chambers and nozzle geometry, but also the actuation mechanism. Specially, the direct needle-Driven piezo injector (DPI) is introduced in this study and compared with the indirectacting Piezo injector (PI) to investigate the injection characteristics and influences on CI combustion performance by using spray visualization, injection rate measurement, and single cylinder diesel engine experiments, as well as numerical simulation for injection rate modeling of DPI. In the spray visualization experiment, a high-speed camera was used to examine spray tip penetration length and spray speed with respect to each injector. Also, in order to investigate injection rate information, which is a significantly dominant factor in combustion characteristics, the Bosch-tube method was adapted under the condition of a back pressure of 4.5 MPa, corresponding to engine motoring pressure. Also, a single-cylinder CRDi (Common-rail direct-injection) engine experiment was carried out to determine the effects of different piezo-acting mechanisms on two-stage fuel injection and CI combustion. From the key results obtained by this study, the direct needle-driven piezo injector has a faster SOI (Start of injection) and EOI (End of injection). In addition, the overall shape of the injection rate of DPI was narrow and the injection had a higher spray speed than that of PI. Also, DPI has a higher heat release rate and peak pressure, as verified by the engine experiment. In particular, it was found that DPI showed the possibility of combustion improvement when applying a pilot injection strategy.

     

电喷发动机燃油泵控制电路的原理及检修

不同车型的电喷发动机对燃油泵的控制方式是不同的。结合几种典型的燃油泵控制电路，分别介绍了燃油泵控制电路的工作原理和检修方法。     

Measurement and simulation of fuel injection pipe pressure and study of its effect on the heat release in a direct injection diesel engine

Fuel injection pipe pressures are measured and simulated to study the effect of fuel injection system characteristies on the heat release in a direct injection diesel engine. The fuel injection simulation is based on a linear model. The governing equations are solved by the finite difference method. The measured fuel pipe pressures and the simulated fuel pipe pressures matched well to each other except for the interval when the nozzle is closing. The effects of the fuel pipe length and the nozzle opening pressure are tested. The longer fuel pipe length causes proportional retardation of the fuel injection time. The higher nozzle opening pressure results in increase of the maximum fuel pipe pressure and shorter combustion duration.     

基于模型的共轨柴油机主喷油量控制算法研究

针对目前高压共轨柴油机电控系统开发周期较长以及开发成本较高的问题,通过研究基于模型的软件开发流程,在Matlab/Simulink环境下建立了高压共轨柴油机主喷油量控制算法模型,其中包括烟度限值控制模型、启动油量控制模型、怠速油量控制模型、怠速PID控制模型以及油量脉宽转换模型;对控制算法模型的关键MAP图进行了标定以验证该控制算法模型的有效性,并在使用INCA标定软件建立监控和标定的发动机试验台架上进行了一系列试验。试验结果表明,发动机启动过程迅速,且正常工况下转速稳定,并能根据环境情况和发动机的当前需求自动调节目标油量;该控制算法能够较好地满足发动机起动、怠速以及正常工况的控制需求。     

A study on fuel spray of spark-ignited direct injection engine using laser image technology

One of the important research for developing a spark-ignited direct injection engine is optimization of the fuel spray distribution and air flow field in the cylinder. Therefore, spray pattern and mean fuel droplet size of swirl injector were investigated using Laser Light Sheet Photography and PDPA' respectively. And, for the formation of stratified mixture with adequate strength near a spark plug at injection mode in compression stroke, spray distribution after impingement on flat piston or bowl piston in a transparent motoring engine was visualized for the three different injector positions. KIA Motors Corp.     

Measurement and analysis of injection characteristics among each nozzle hole within a heavy-duty diesel engine

The mass flow rate from each injector nozzle hole of a diesel engine influences the distribution, atomization, and combustion of fuel in the chamber. Thus affecting the power, the fuel economy, and the emission quality of the diesel engine. A spray momentum flux test bench was built and used to measure the injection rate from each nozzle hole of a multi-hole nozzle in this study. Selected force sensors used for data acquisition were one of the integral parts of the set-up. The influence of the force sensors’ installed position (location in the set-up) on measured results, were analyzed and the optimum position that ensures independence of the results, determined. Additionally, the effects of injection pressure, injection pulse width and injection hole diameter on the injection characteristics were also investigated. Furthermore, in this research, the reliability and robustness of Strain sensor and Piezoelectric sensors were analyzed with regards to their response. The analysis showed that, strain sensors have weak dynamic response characteristic compared to piezoelectric sensors also, the measured result obtained from strain sensors fluctuated greatly. Piezoelectric force sensor gave a more reliable and stable measurement, comparatively. The accuracy of the results were affected by the installation position of the sensors. A distance of 16 mm (between nozzle hole exit and sensor surface) was determined to be adequate for the acquisition of reliable experimental data. As the injection pressure gets higher (during injection), the rate of mass flow increased, the average cycle-to-cycle variation coefficient and nozzle-to-nozzle variability coefficient of injection quantity decreased. Hence, improving the consistency of each cycle and the uniformity of each hole. In addition, increasing the injection pulse width decreased the average cycle-to-cycle variation coefficient. Also, nozzle-to-nozzle variability coefficient had minimal or no influence with regards to injection pressure. At 80 MPa, the uniformity of injection from the multi-hole nozzle improved significantly. In summary, the larger the hole diameters, the higher the maximum value of mass flow rate and the fuel injection quantity.     

An investigation on the spray characteristics of DME with variation of ambient pressure using the common rail fuel injection system

We investigated the DME spray characteristics about varied ambient pressure and fuel injection pressure using the common rail fuel injection system when the nozzle holes diameter is varied. The common rail fuel injection system and fuel cooling system were used since DME has compressibility and vaporization at atmospheric temperature. The fuel injection quantity and spray characteristics were measured. The spray was analyzed for spray shape, penetration length, and spray angle at the six nozzle holes. There are two types of injectors: 0.166 mm diameter and 0.250 mm diameter. The ambient pressure, which was based on gage pressure, was 0, 2.5, and 5 MPa. The fuel injection pressure was varied by 5 MPa from 35 to 70 MPa. By comparing with the common injector, using the converted injector it was shown that the DME injection quantity was increased 127% but it didn??t have the same low heating value. Both the common and converted injectors had symmetric spray shapes. In case of converted injector, there were asymmetrical spray shapes until 1.2 ms, but after 1.2 ms the spray shapes were symmetric. Also, the converted injector had shorter penetration length and wider spray angle than the common injector.     

Correction strategy of fuel injection quantity during pilot-main injection for common rail system

Journal of Mechanical Science and Technology - Common rail system is a key technology of energy saving and emission reduction for modern diesel engines. Multiple injection, as one of the most...     

喷油泵实验台液压系统的设计

介绍了一种喷油泵试液压式验台,该试验台采用气液增压泵将气体低压转换为液体高压,并向喷油泵提供高压油.具有体积小、配置灵活、发热少、节省能源等优点.     

Investigation of emission characteristics affected by new cooling system in a diesel engine

In a typical cooling system of automotive engine, a mechanical water pump is used to control the flow rate of coolant. However, this traditional cooling system is not suitable for a high efficiency performance in terms of fuel economy and exhaust emission. Therefore, it is necessary to develop a new technology for engine cooling systems. These days, the electronic water pump is spotlighted as the new cooling system of an engine. The new cooling system can provide more flexible control of the coolant flow rate and the engine temperature, which used to be strongly relied on the engine driving conditions such as load and speed. In this study, an engine experiment was carried out on a New European Drive Cycle (NEDC) with a 2.7L diesel engine. The electric water pump operated by BLDC motor and the electronic valve were installed in the cooling system to control the coolant flow rate and temperature. This paper explains that the exhaust emissions were reduced with an increase in the engine temperature and a decrease in the coolant flow. From this experiment, we found that increasing coolant temperature had a significant effect on reducing the emissions (e.g. THC and CO). Decreasing coolant flow also affected the reduction of emissions. In contrast, NOx emission was observed to increase in these conditions. This paper was presented at the 7th JSME-KSME Thermal and Fluids Engineering Conference, Sapporo, Japan, October 2008. Kyung-Wook Choi received his B.S. degree in Mechanical Engineering from Hanyang University, Korea, in 2006. He is now working on a doctoral degree in Hanyang University. Kyung-Wook’s research interests include Hybrid Electric Vehicle, Internal Engine Combustion, and Engine Cooling System. Ki-bum Kim was awarded a bachelor’s degree in naval architecture and ocean engineering from Chung-Nam National University in the Republic of Korea. In August 2001, he began graduate study at the University of Florida. Kibum graduated with a Master of Science degree in mechanical engineering from the University of Florida in August 2003. He went on to earn his Ph.D. in mechanical engineering, also at the University of Florida, in August 2006. He is working as a research professor at Hanyang University. Ki-Hyung Lee is a Professor at the department of mechanical engineering in Hanyang University. He received his B.S and M.S degree in Hanyang University in 1983 and 1986. Then he graduated with a Ph.D. degree in mechanical Engineering at Kobe University, Japan in 1989. He worked as a research engineer at Nissan motor’s central technical center for 4 years.     

Numerical analysis of the combustion process in a four-stroke compressed natural gas engine with direct injection system

In this paper, a numerical study to simulate and analyze the combustion process occurred in a compressed natural gas direct injection (CNG-DI) engine by using a multi-dimensional computational fluid dynamics (CFD) code was presented. The investigation was performed on a single cylinder of the 1.6-liter engine running at wide open throttle at a fixed speed of 2000 rpm. The mesh generation was established via an embedded algorithm for moving meshes and boundaries for providing a more accurate transient condition of the operating engine. The combustion process was characterized with the eddy-break-up model of Magnussen for unpremixed or diffusion reaction. The modeling of gaseous fuel injection was described to define the start and end of injection timing. The utilized ignition strategy into the computational mesh was also explained to obtain the real spark ignition timing. The natural gas employed is considered to be 100% methane (CH₄) with three global step reaction scheme. The CFD simulation was started from the intake valves opening until the time before exhaust valves opening. The results of CFD simulation were then compared with the data obtained from the single-cylinder engine experiment and showed a close agreement. For verification purpose, comparison between numerical and experimental work are in the form of average in-cylinder pressure, engine power as well as emission level of CO and NO. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007.