Elimination of Fuel Pressure Fluctuation and Multi-injection Fuel Mass Deviation of High Pressure Common-rail Fuel Injection System

The influence of fuel pressure fluctuation on multi-injection fuel mass deviation has been studied a lot,but the fuel pressure fluctuation at injector inlet is still not eliminated efficiently.In this paper,a new type of hydraulic filter consisting of a damping hole and a chamber is developed for elimination of fuel pressure fluctuation and multi-injection fuel mass deviation.Linear model of the improved high pressure common-rail system（HPCRS）including injector,the pipe connecting common-rail with injector and the hydraulic filter is built.Fuel pressure fluctuation at injector inlet,on which frequency domain analysis is conducted through fast Fourier transformation,is acquired at different target pressure and different damping hole diameter experimentally.The linear model is validated and can predict the natural frequencies of the system.Influence of damping hole diameter on fuel pressure fluctuation is analyzed qualitatively based on the linear model,and it can be inferred that an optimal diameter of the damping hole for elimination of fuel pressure fluctuation exists.Fuel pressure fluctuation and fuel mass deviation under different damping hole diameters are measured experimentally,and it is testified that the amplitude of both fuel pressure fluctuation and fuel mass deviation decreases first and then increases with the increasing of damping hole diameter.The amplitude of main injection fuel mass deviation can be reduced by 73%at most under pilot-main injection mode,and the amplitude of post injection fuel mass deviation can be reduced by 92%at most under main-post injection mode.Fuel mass of a single injection increases with the increasing of the damping hole diameter.The hydraulic filter proposed by this research can be potentially used to eliminate fuel pressure fluctuation at injector inlet and improve the stability of HPCRS fuel injection.

An experimental study on RP-3 jet fuel injection on a common rail injection system

RP-3 jet fuel could be an alternative fuel for diesel engines.In this study,the injection characteristics of RP-3jet fuel under single and split injection strategies were investigated and compared with diesel fuel.The experimental results indicate that RP-3 jet fuel has slightly shorter injection delay time than diesel fuel,but this difference is negligible in actual engine operations.Further,although the lower density and viscosity of RP-3 jet fuel lead to higher volumetric injection rates and cycle-based injection quantities,the cycle-based injection mass and the mass injection rates at the stable injection stage of RP-3 jet fuel are close to or slightly lower than those of diesel fuel.Based on these experimental observations,it could be concluded that fuel physical properties are the secondary factor influencing the injection characteristics in both single and split injection strategies,as RP-3 jet fuel and diesel fuel are taken for comparison.

STRUCTURE PARAMETERS DESIGN AND PERFORMANCE TEST OF FUEL INJECTION SYSTEM

Based on the numerical simulation analysis, structure parameters of the high pressure fuel pump and common rail as well as flow limiter are designed and the GD-1 high pressure common rail fuel injection system is self-developed. Fuel injection characteristics experiment is performed on the GD-1 system. And double-factor variance analysis is applied to investigate the influence of the rail pressure and injection pulse width on the consistency of fuel injection quantity, thus to test whether the design of structure parameters is sound accordingly. The results of experiment and test show that rail pressure and injection pulse width as well as their mutual-effect have no influence on the injection quantity consistency, which proves that the structure parameters design is successful and performance of GD-1 system is sound.

高压共轨柴油机国产芯片控制系统研究

针对现有高压共轨柴油机电控单元高度依赖进口芯片、自主不足的问题,提出了基于全国产芯片的高压共轨柴油机电控单元方案。所设计的国产控制单元选用兆易创新的GD32F450芯片为控制核心,承担发动机数据采样、处理、存储与控制任务。首先,采用Boost升压电路提供喷油器峰值电流,利用分立器件设计双边驱动与电流反馈电路,在不依赖进口专用芯片的条件下,对喷油器驱动电流进行闭环控制;然后,基于FreeRTOS操作系统,开发高压共轨柴油机底层驱动软件,实现对不同任务调度周期的精准控制;最后,对所设计的电控单元进行了实验验证。结果表明,所设计的国产高压共轨柴油机电控单元功能齐全、工作稳定,双边驱动电路典型峰值电流为22 A,维持电流为10 A,最小喷射间隔时间为200μs,多次喷射性能与Bosch系统相当。发动机不同转速条件下任务调度周期精准、实时性好,研究证实了高压共轨柴油机电控单元全国产化方案的可行性,对推动发动机电控技术自主可控提供了有益参考。

Design and optimization of a novel electrically controlled high pressure fuel injection system for heavy fuel aircraft piston engine

The heavy fuel compression ignition engines are widely equipped as aircraft piston engines. The fuel injection system is one of the key technologies that determines the performance of engine. One of the main challenges is to precisely control the injected fuel quantity and flow rate in the presence of pressure fluctuation. This challenge is even more serious for heavy fuel. An original design for electrically controlled high pressure fuel injection system called Multi-Pumppressure-reservoirs fuel injection System(MPS) was demonstrated to reduce the pressure fluctuation and help keep injection stable. MPS was compared with an ordinary high pressure Common Rail fuel injection System(CRS). This work established one-dimensional AMESim and mathematical models for both CRS and MPS to study the effect of different structures and geometric parameters on the pressure fluctuations. The calculations show that the average fuel pressure fluctuation of MPS can be reduced by 57% for the crankshaft speed of 1900 r/min, and the pressure fluctuation before injection reduced by 100%. It is concluded that the pressure performance of MPS is less sensitive to pressure reservoir volume than that of CRS, and there is an opportunity for further volume reduction.

喷油器柱塞副动态泄漏及特性

为了研究高压共轨喷油器柱塞副的动态泄漏特性,建立了柱塞副间隙燃油流动的数学模型,通过有限差分法对数学模型进行数值计算,研究了不同轨压下柱塞副燃油的平均动态泄漏率的变化趋势,与试验值进行对比,验证该数学模型的有效性,并分析了轨压、进口燃油温度、柱塞最大升程和喷射脉宽四种因素对柱塞副动态泄漏量的影响及在不同柱塞速度下,油膜压力、厚度和温度参数的变化趋势。结果表明,在一个喷油循环内,动态泄漏率的变化曲线与控制腔油压变化曲线相似,平均动态泄漏率随着喷油器的轨压、入口燃油温度和柱塞最大升程的增加而增加,但随着喷射脉宽的增加而减小;随着柱塞速度由正速度到负速度的过程,油膜的厚度逐渐变薄,油膜的温度整体上升,油膜的压力变小。

Design of Rail Pressure Tracking Controller for Novel Fuel Injection System

This paper proposes a rail pressure tracking controller based on a novel common rail system. A mathematical model, based on physical equations, is developed and used for feed forward control design. Rail pressure peak sampling mechanism is designed to remove the disturbance of rail pressure due to fuel injection. All enhanced tracking differentiator is designed to get smooth tracking signal and exact differential signal from signal with noise. Double loop control strategy is designed to decouple the system and to improve dynamic performance of the system. Experimental results indicate that fluctuation of rail pressure is within il MPa in steady condition, while within ±3 MPa in transient condition, which verifies the effectiveness of the proposed rail pressure control strategy.

汽车发动机高压共轨系统轨压特性分析与优化

基于关键零/部件参数,建立了汽车发动机高压共轨喷射系统的数学模型,使用AMESim软件进行仿真模拟,并通过试验分析验证了该仿真模型的准确性。通过对系统轨压波动和压力特性进行仿真分析,得出共轨管长度、内径和高压油管内径是影响系统轨压特性的重要参数。针对原始共轨管和高压油管模型,利用响应曲面法对共轨管和高压油管参数进行优化分析,并得出以平均轨压设定值为目标的共轨管和高压油管的最佳结构参数。经过优化后,汽车发动机高压共轨喷射系统的平均轨压提高了0.65%,整体轨压波动平均值降低了79.48%,单次喷射过程中轨压波动平均值降低了27.89%,平均喷油压力提高了0.63%,其喷油特性得到明显的改善。

非道路柴油机冷却水套流动传热分析与优化

冷却水套作为柴油机的核心结构,其流动与传热特性直接影响着柴油机的可靠性和使用寿命。以某两缸高压共轨柴油机为研究对象,为了解该发动机冷却水套流动与传热性能,以水套速度场、温度场、换热系数等空间分布参数为判据,重点对冷却水套关键区域的流动和传热特性进行分析,同时提出优化方案。仿真结果表明:发动机整体冷却液流动性差,平均流速低于0.5m/s,缸体进气侧冷却水套上部出现了流动死区;通过对冷却系统性能参数和冷却水套结构进行优化,冷却水套进出口压力损失减小,整体冷却液平均流速较原方案提高了173.91%,整体平均换热系数较原方案提高了41.93%,整体冷却水套流动均匀性得到改善。

双升程电控喷油器多次喷射油量波动特性研究

为实现船用柴油机高压共轨系统喷射的柔性和稳定控制,提出一种双升程电控喷油器,基于搭建的喷油器AMESim仿真模型,探究了喷油器不同多次喷射模式下的油量波动特性.结果表明:大升程预喷模式下的主喷量标准差随预喷量的增加先上升后下降,而小升程预喷模式下的主喷量标准差随预喷量呈幅值逐渐降低的波动变化趋势.总体上,在预喷量为161~660 mm^(3)范围,小升程预喷模式在降低主喷量波动程度方面比大升程预喷模式更占优势.预喷射采用小升程喷射模式且预喷量一定时,升程切换延迟为0.2 ms的靴形主喷模式在降低主喷量波动程度方面略优于相同主喷脉宽或相同单次喷射油量的大升程主喷模式.大升程和小升程后喷模式下的后喷量标准差随主喷脉宽和目标后喷量均呈波动变化趋势,且小升程后喷模式下的后喷量标准差波动程度更小.与大升程后喷模式相比,小升程后喷模式在降低后喷量波动程度方面更占优势.

EEMD—模糊聚类在共轨系统故障诊断上的应用研究

高压共轨柴油机作为一种往复式运行的机械,其故障的发生是一个具有模糊性的渐变过程。针对高压共轨柴油机供油系统故障程度诊断中出现的特征值识别困难,分类界限模糊等问题,提出了一种基于EEMD(集合经验模态分解)—模糊聚类的故障诊断方法。通过EEMD将供油系统轨压信号分解为一系列的IMF(固有模态函数),利用过零率曲线确定的特征提取准则并提取本征模态函数中的特征值,建立模糊聚类模型进行故障程度的诊断。在此基础上通过台架实验获得轨压信号,提取了相关特征值进行识别,分析了诊断结果,验证了该方法的正确性。

回油背压对高压共轨喷油器喷油特性影响的研究

高压共轨喷油器是柴油机高压共轨电控系统中最重要的一个部件,其喷油特性(如喷油器量)的优劣将直接影响发动机的性能表现。喷油器的喷射特性不仅受到喷油器的结构参数的影响,同时在喷射过程中还受到外界工作环境的影响,比如喷油器喷射时发动机缸内的背压,以及喷油器工作时的回油通道中的背压。本文主要对某高压共轨喷油器进行台架试验测试,研究喷油器回油背压对喷油特性的影响,并分析产生影响的原因,为开发新型的燃油喷射系统提供试验数据。

转速和高压共轨燃油系统参数对共轨管压力波动的影响

为减小柴油机高压共轨系统的共轨管内压力波动,使用AVL Boost Hydsim软件建立某柴油机高压油泵及共轨管一维仿真模型,分析柴油机转速和柱塞直径、柱塞腔容积、柱塞个数、共轨管内径等高压共轨燃油系统结构参数对共轨管压力波动的影响。仿真结果表明:增大柴油机转速、增大高压油泵柱塞直径、减小高压油泵柱塞腔容积,可以减小轨压波动;增大共轨管内径能有效抑制压力波动;柱塞个数变化使供油次数和喷油器喷油次数一致时,可以减小轨压波动。

叉车柴油机加速工况声品质改进试验研究

为降低某叉车柴油机加速过程中的噪声,试验分析柴油机加速异响产生的原因,研究喷油规律对加速噪声的影响,分析声品质参数,并提出改进方案。试验结果表明:柴油机急加速“嘎嘎”声是由燃烧过程缸内压力升高率过大导致,增加预喷量可以在一定程度上降低噪声水平,但对加速异响几乎没有影响;减小喷油提前角可以轻微降低加速异响;降低轨压上升率可以明显降低加速异响,轨压上升率由150 MPa/s降低至100 MPa/s,柴油机加速时异响消失,响度的变化趋势与声压级基本一致,尖锐度和粗糙度降低,声品质明显提升。

迈腾B8高压喷油器常见故障诊断

迈腾B8不仅在中国中级车辆的销售市场占有率较高,还是全国汽车技术技能竞赛的主选车型之一。在各类汽车故障中,高压喷油器是故障高发区域之一,对于高压喷油器常见故障及时进行精准诊断,是把握故障原因,做好有效处理的关键。本文主要结合燃油控制电路,对迈腾B8发动机喷油器的喷油过程进行分析,最后以案例的形式,讲解其高压喷油器常见故障的分析诊断过程,最后对于高压喷油器的故障诊断提供几点有效方法参考。通过理论联系案例分析,为更好的把握迈腾B8高压喷油器故障问题提供指导,为高压喷油器的故障诊断和处理提供一些思路和借鉴。

基于LabVIEW的比例压力控制阀自动测试系统

根据某公司比例压力控制阀的出厂测试要求,本文设计了一套比例控制阀自动测试系统。该系统基于LabVIEW编程和PLC控制,可实现共轨管稳定的超高压供给,并自动实现比例压力控制阀的耐久测试、流量滞环测试及压力-流量测试,且操作简便,满足企业需求。

大流量高压共轨供油泵参数敏感性分析

某柴油机需要较大供油流量,为优化大流量高压共轨供油泵(简称大流量泵)参数,使供油量及容积效率达标,搭建了大流量泵液力系统仿真模型并进行试验验证,应用蒙特卡洛方法仿真计算大流量泵在不同系列参数下的性能,通过线性回归与随机森林回归进行参数敏感性分析。结果表明:2种回归分析方法计算结果基本一致,大流量泵在标定工况下的供油量和容积效率的高敏感性参数均为柱塞直径、进油阀座锥角、进油压力、柱塞升程和进油计量阀内径。

喷油特性对F-T煤制油压力振荡影响规律研究

为了减小燃烧噪声,确定影响柴油机高频压力振荡的关键因素,在某型电控高压共轨柴油发动机上燃用的清洁代用燃料Fischer-Tropsch(F-T)煤制油,选取柴油机典型运行工况,研究不同喷油特性条件下柴油机燃烧压力振荡的时域和频域特性。结果表明:推后主喷提前角和提前预喷提前角会使放热率降低,压力振荡幅值减小,气缸压力级也有明显减小的趋势;减小预喷油量会使压力升高率和放热率降低,气缸声压级减小,压力振荡现象减缓,使燃烧更加柔和;提高喷射压力,会使喷油速率增大,燃油雾化效果增强,混合气放热率提升,放热率曲线也随之上升,气缸声压级增大,发动机缸内燃烧压力振荡幅值增大。喷射压力是影响压力振荡的最显著的参数,喷射压力从85MPa上升至115MPa时,压力振荡幅值增加一倍以上;预喷油量对F-T煤制油发动机的燃烧压力振荡影响不显著;同时压力振荡的产生与放热率的变化呈现出较强的相关性。

超磁致伸缩驱动高压共轨式喷油器的结构设计及喷油特性分析

针对现有喷油器存在的喷油速率低、喷油脉宽大、响应速率慢的问题,提出了一种超磁致伸缩驱动高压共轨式喷油器的设计方案。简述了该高压共轨式喷油器的整体设计及工作原理,并且在Jiles-Atherton磁滞模型和液压传动理论基础上建立数学模型;采用COMSOL建立了驱动部分仿真模型,并进行输出位移和应力特性分析,采用AMESim建立了喷油器整体模型,并进行喷油速率分析;搭建试验平台,验证了超磁致伸缩驱动高压共轨式喷油器设计方案的有效性。结果显示:当线圈电流为3.6 A时,超磁致伸缩棒的最大输出位移可达52μm;在160 MPa的压力下喷油最低脉宽从1 ms降低到0.15 ms,并且无论脉宽长短,其脉宽-喷油量均具有良好的线性度。结果表明,提出的设计方案可行,为研制出一种高性能的高压共轨式喷油器奠定了理论和技术基础。

基于高压共轨燃油系统和废气再循环的柴油发动机低排放研究

柴油发动机的排放会对环境和人类健康造成不良影响,高压共轨燃油系统和废气再循环技术是目前柴油发动机低排放技术中应用广泛的技术方案。该文基于柴油机排放污染物生成机理,系统论述了高压共轨燃油系统的基本原理和优势,探讨了其在柴油发动机低排放方面的应用、实现方法与应用特点,并提出了未来研究的方向。研究结果表明,高压共轨燃油系统和废气再循环技术可以有效降低柴油发动机的排放量,但仍存在一些技术问题需要解决,如NOx和PM的同时降低等。因此,未来的研究应注重对这些问题的深入探究,并继续优化和改进这些技术方案。