电控喷油器喷油特性的仿真与试验研究

建立了电控喷油器的数值仿真模型,利用试验数据对模型进行了验证。基于该模型研究了喷油器不同喷孔直径和喷孔数的组合对喷油速率的影响。研究结果表明:运用软件仿真技术对高压共轨燃油系统进行仿真计算和优化设计是一种有效方法。     

压电喷油器驱动电路设计研究

针对压电喷油器的实际使用要求和压电驱动器的具体性能参数,基于脉宽调制(PWM)控制方式,采用Adμc841单片机和大功率IGBT开关管设计了压电喷油器的驱动电路。利用MATLAB/SIMULINK对充放电回路的限流电感进行了优化设计,最后对设计的驱动电路进行了试验。试验结果表明,设计的驱动电路可实现对压电喷油器的精确快速控制;当压电喷油器内压电驱动器等效电容为7μF时,驱动电路的充放电时间均小于0.1ms,最大驱动电压可达200V,并且喷油器可实现最小间隔0.2ms的多次喷射。     

柴油机喷油器体锻件锻造新工艺

对柴油机喷油器体锻件锻造工艺的国内外情况进行了概述,介绍了楔横轧精密制坯－立铸成形工艺,并对各种锻造工艺进行了综合比较。     

缸盖油水混合故障原因分析及对策

介绍了用户发现缸盖的油水混合故障情况,通过对返回件的泄漏复试、解剖分析,认为引起该故障产生的原因是:喷油器铜套壁薄开裂;喷油嘴与铜套内铜垫配合不好发生漏油;喷油器回油通道堵塞导致铜套内部压力升高而开裂;冷却液质量不良使喷油器铜套腐蚀穿孔;喷油器O形圈损坏导致密封不严;喷油器嘴密封不严。通过采取以下措施使该故障得以解决:严格控制铜套质量并改进铜套结构;使用材料较好的O形圈,改进O形圈安装过程控制;改进喷油器嘴配合结构;保证喷油器与铜套间垫片密封压力适当;避免连接管头部和喷油器进油口被碰伤、损伤;确保冷却液质量。     

气相色谱玻璃衬管中的玻璃棉对仪器重现性影响的研究

本文研究气相色谱进样系统中,玻璃衬管中有、无玻璃棉填充以及样品浓度的高低对仪器的重现性的影响。     

Effects of inlet blockage of gas-liquid scheme injector on acoustic tuning for acoustic damping in a combustion chamber

In a rocket combustor, purely acoustic tuning of gas-liquid scheme injector is studied numerically for acoustic absorption by adopting linear acoustic analysis. Acoustic behavior in the combustor with a single injector is investigated to assure the optimum injector length. Acoustic-absorption effect of the injector is evaluated for cold condition by the quantitative parameter of damping factor as a function of injector length in the chamber for several boundary absorption coefficients. Irrespective of boundary absorption at the chamber wall, it is assured that the optimum tuning-length of the injector corresponds to half of a full wavelength of the first longitudinal overtone mode traveling in the injector with the acoustic frequency intended for damping in the chamber. Although boundary absorption affects little the tuning length of the injector, it appreciably affects damping capacity. Acoustic absorption at the wall increases with boundary absorption coefficient, but purely acoustic-damping effect induced by the tuned injector decreases with the coefficient. As another design parameter, effects of blockage at the injector inlet on acoustic tuning are investigated. It is found that the optimum injector length is shifted depending on the blockage ratio. Suitable combination of injector length and blockage should be made for maximum damping.     

喷油嘴针阀体头部断裂失效分析

采用EPIPHOT300金相显微镜图像分析系统和VH-5维氏硬度计图像分析系统,对18CR2nI4WA材料喷油嘴针阀体头部断裂处进行了金相显微分析和硬度测试.根据试验结果,着重分析了其断裂失效的机理,并提出了相应改进措施.     

Combined effect of multi-injection scheme,injector nozzle bore,and biodiesel blends on combustion and performance characteristics of diesel engine

Many researchers have conducted extensive experimental and numerical studies to explore the influences of multiple types of fuels. The high demand of energy in the world has led to the growing crisis and depletion of fossil fuels. Therefore, the researchers have focused on investigating renewable energy sources like biodiesel with the aim of suggesting, which energy is more friendly to the environment. Biodiesel has specifications for using it as an alternative fuel to traditional fossil fuels. Whereas, the use of biodiesel fuel in the original design of Diesel engine can emit a higher percentage of nitrogen oxides (NO_x). Therefore, to reduce the harmful emissions of the fuel, the injection schemes and injector nozzle bore (INB) of the engine were modified. The present research combines the effect of the nozzle hole diameters and split injection scheme on the performance and combustion parameters of compression ignition (CI) engine was investigated. The engine was fueled with diesel blended of different proportions (Sp20, Sp40, Sp60, and Sp100) of spirulina biodiesel to prove the suitability of this blend as an alternative fuel. The injector nozzle has three injection holes, and the diameter of the three modified holes of the nozzle is changing (from 0.20 to 0.28 mm, step 0.02 mm) along with two types of scheme injection (double and triple). Furthermore, the influence of the direct injection Diesel-RK model, single-cylinder, four-stroke engine; constant compression ratio (17.5:1), engine speed (1500 rpm), and naturally aspired engine at full load condition are studied. A comparison of the present simulation is compared with published results to validate the present simulation model for conventional baseline Diesel for validation. The simulation was done to investigate and present a comparative study with the conventional baseline Diesel engine. The double injection scheme shows a decrease by 1.8%, 1.7%, and 1.9% for parameters of peak cylinder pressure (PCP), peak cylinder temperature (PCT), and maximum rate of pressure rise, respectively. Whereas, the specific fuel consumption (SFC) and break thermal efficiency are increased by 8.7% and 9.33%, respectively. The results showed a reduction by 2.1%, 20.5%, 22.1%, and 3.2% in PCP, PCT, maximum rate of pressure rise, and break thermal efficiency, respectively. Moreover, the SFC is increased by 3.1% with the modified INB 0.28 (mm).     

Correlating armature and needle dynamics with voltage waveforms of solenoid-actuated GDI injector

The injector voltage hump that appears near the needle closing has been used for the real-time monitoring and feedback control of fuel injection duration in modern engines. This voltage hump has been thought to result from the abrupt change in electromagnetic induction by the stoppage of needle motion but detailed electromagnetic processes and associated armature and needle dynamics during the needle closing have not been thoroughly investigated in a wide range of injection conditions, which knowledge is crucial for the delicate control of fuel injection based on the voltage hump. The current study analyzes the transient armature and needle dynamics of a solenoid-actuated gasoline direct injection injector using an X-ray phase-contrast imaging technique. Then, the results are correlated with voltage waveforms during the needle closing transient under various injection pressures, injection pulse durations, and dwell times of split injections. The time derivatives of voltage waveforms showed lower and upper peaks in order in the regime of the voltage hump. Inconsistent with conventional understandings, the lower peak timing of the voltage derivative did not match with the timing of needle closing (end of injection) but rather matched with the abrupt descent timing of the armature and needle. The inflection timing and upper peak timing of the voltage derivative matched with the timings of actual needle closing and armature closing respectively. The amplitude of the voltage hump was near linearly dependent on the needle closing speed. The needle closing speed decreased upon the decrease of injection pulse duration and injection pressure which made it difficult to detect the voltage humps in ballistic injection regimes and low injection pressures. In split injection conditions, the voltage hump of the first injection was not detectable if the dwell time was shorter than the needle closing delay, the time from the current cut-off to the actual needle closing.     

超磁致伸缩式喷油器的结构参数优化及其响应特性研究

为提高现有喷油器的动态响应特性,采用超磁致伸缩驱动器（GMA）通过液压腔驱动球阀的形式,提出一种超磁致伸缩式喷油器(GMI)的设计方案。在阐述该喷油器的结构组成和工作原理基础上,基于Jiles-Atherton磁滞模型建立GMA的输出力模型,将其与喷油器液力模型耦合,建立了该喷油器的电-磁-机-液多场耦合模型;基于MATLAB/Simulink模块搭建该喷油器的仿真模型,分析不同偏置磁场下GMA的磁致伸缩曲线,以及不同GMA预应力下的球阀响应曲线;采用遗传算法,选取针阀响应时间为评价指标,对GMA的预应力、进出油孔直径、控制腔容积等关键参数进行优化。结果表明：设计的超磁致伸缩式喷油器具有良好的响应特性,优化使针阀开启延迟降低27.3%,针阀上升时间降低11.0%,针阀关闭延迟降低19.5%,针阀下降时间降低9.9%。