燃油喷射器电控性能的改进设计研究

在电控喷油器电磁动态工作性能研究基础上,分析了影响电磁动态特性的主要因素。通过测量驱动电路中串联小电阻的电压变化,得到电磁线圈电流响应特性。线圈安匝数和磁极气隙是影响电磁动态特性的主要因素。结合实验结果提出喷油器结构改进设计原则,对结构改进后的喷油器电磁响应特性进行了实验验证。结果证明电磁响应特性得到了提高,开启响应时间由原来的1.4 ms提高到1.1 ms,关闭响应时间缩短1.4 ms。     

GDI喷油器针阀动力学特性研究

针阀动力学行为是影响GDI(汽油直接喷射式）喷油器工作稳定性和可靠性的关键因素。为了揭示不同参数对针阀动力学特性的影响机理,以某款GDI多孔喷油器为对象,依据针阀的受力特点建立了针阀动力学模型和GDI喷油器AMESim工作过程仿真模型,仿真分析了阀座锥角、阀座与钢球的接触方式、阀针运动质量等参数对针阀动力学特性的影响规律。结果表明：适当减小阀座锥角、增大阀座与钢球的接触面积、减小针阀运动质量可有效抑制开启或落座过程中针阀的振荡幅度。根据仿真分析结果对GDI喷油器的结构进行了综合改进,结果表明,结构改进后,GDI喷油器针阀的动力学特性得到显著改善。     

电控喷油器的一种新型磁路结构

为提高喷油器的动态响应性能,以某款电控喷油器为研究对象,通过在其铁芯与导向管之间增加由不导磁材料制成的隔磁环开发了一种新型磁路结构。通过电磁场仿真分析了改进前后喷油器电磁性能的变化特点以及轭铁厚度对电磁性能的影响规律。结果表明：增加隔磁环能加快电磁力的上升速度,有效缩短喷油器的开启滞后时间,但饱和电磁力增大,造成落座滞后时间延长;适当减小轭铁厚度基本不影响电磁力的上升速度,但减小轭铁厚度会使磁阻增大,饱和电磁力降低,这样可有效缩短落座滞后时间。根据以上分析结果对喷油器进行了综合优化,并通过实验对其改进效果进行了验证,结果表明：优化后与优化前相比,喷油器的开启滞后时间缩短了0.25ms,落座滞后时间缩短了0.3ms。     

高压共轨电控柴油机喷射系统的优化设计

介绍一款以高压共轨电控装置为基础,对其电控喷油器结构进行优化和改进的燃料喷射系统,阐述了该系统的工作原理和结构组成。介绍了喷油器的工作过程,并对电控喷油器的电气参数进行了分析。改进之后该系统喷油器的电磁阀具有体积小、耐高压、耐高温、耐震动和响应速度快等特点,实现喷射压力和喷油量的控制,从而优化喷油特性形状,降低柴油机噪声和大大减少废气的排放量。     

电控喷油器关键结构参数的匹配优化研究

针对电控喷油器动态响应性能需要改善的问题,运用Ansoft Maxwell电磁场仿真软件建立了喷油器的计算模型,对包括轭铁厚度、铁芯外径、衔铁长度、工作气隙、线圈匝数和线圈电阻在内的关键结构参数对其动态响应性能的影响规律进行了研究,在此基础上以各关键结构参数作为设计变量,开启滞后时间和落座滞后时间作为目标函数建立了相应的优化模型,通过遗传算法对这些结构参数进行了匹配优化,并通过仿真和试验的方法对该优化方案的有效性进行了验证。研究结果表明,经过优化后电控喷油器的开启滞后时间和落座滞后时间分别缩短了33.1%和37.1%,其动态响应性能得到了提高。     

甲醇喷油器结构参数对液力响应的正交试验研究

甲醇喷油器作为高压共轨喷射系统的核心部件,其性能优劣对甲醇发动机的各项特性有重要影响。通过对甲醇喷油器主要结构进行数学建模,得出影响液力响应的结构参数。利用AVL Hydsim软件对甲醇喷油器建立了仿真计算模型,结果表明:进油孔孔径、柱塞直径、针阀直径、柱塞弹簧预紧力是影响喷油器液力响应的4个关键因素。由此,选择合理范围的结构参数进行正交试验,得出各个参数对喷油器液力响应各个阶段的影响程度,其中进油孔孔径对液力响应4个动态指标影响均极为显著,由此优选出最佳参数。优化方案对提高液力响应有明显的效果。     

42CrMo喷油器体端面开裂分析与工艺优化

针对某公司42CrMo喷油器体端面易开裂情况,完成了断口形貌、化学成分和硬度以及金相观察等分析测试,并应用有限元方法对喷油器体密封端面开裂处进行应力分析,发现其两进油孔处应力超出标准;在此基础上对喷油器体热处理和加工工艺优化并应用于实际生产,改进工艺后的喷油器总成性能检测合格.     

基于响应面法的丢手释放接头优化设计

为优化丢手释放接头的结构强度和重量,提出以应力和质量为目标函数的多目标优化设计方法.将响应面设计方法与有限元数值分析结合,建立了应力和质量关于结构参数的响应面模型,分析了参数间的交互效应.基于响应面模型,通过多目标优化分析获得了释放接头的最佳结构参数配置.优化后的结构应力下降19.5％,而质量增长较小.数值及实验验证表...     

减压阀的噪声估计与改进设计

调节阀在工作过程中普遍存在着噪声,所以噪声分析和噪声消除非常必要.调节阀振动和噪声过大,会导致控制阀门全开.在分析了振动和噪声产生原因之后,利用某公司提出的噪声估算公式进行噪声估算,最终提出了阀门内部结构改进方案.在阀门内部结构设计过程中,主要就阀芯的结构、套筒的设计、安装和阀芯的运动限位做了改进.为了保护阀内件不受损坏,延长阀门的使用寿命,特设计5％以下的行程为空行程.最后经过冷水打压实验,改造后的阀门性能较好,能满足要求.     

平底从动件凸轮机构考虑动态弹流润滑油膜时动力响应的研究

在分析研究了平底从动件凸轮机构中凸轮与从动件之间的油膜的动力性能的基础上,提出了把此油膜看成是存在于凸轮与从动件之间的一个质量—弹簧—阻尼系统的假设,建立了相应的动力学模型和运动微分方程,并运用弹流理论和凸轮机构动力学,对油膜厚度、油膜等效刚度和考虑油膜影响的平底从动件凸轮机构的动力响应进行了计算和分析,所得到的动力响应变化对于设计高速凸轮机构具有较大的实用价值。     

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.     

喷油器技术状况检测技术研究

随着喷油器使用时间的增加,其主要部位和零部件的技术状况会下降,影响喷油质量,进而影响发动机的性能。本文根据检测目标对当前的喷油器技术状况检测技术进行了分类,总结了传统检测方法,并列举了部分改进方法及检测效果。     

粉末冶金新技术生产汽车喷油器压块

对汽车喷油器压块受力状态及产品结构进行分析,用粉末冶金成形、烧结新技术,成功研制出各项性能指标均达到要求的汽车喷油器压块.结果显示对于粉末冶金Fe-Ni-Mo-Cu-C合金材料,提高压坯密度可以提高产品强度但提高有限,延长烧结时间,提高烧结温度到1250℃,可以使Ni烧结基本达到均匀合金化,经碳氮共渗热处理后强度有显著...     

基于MOSA算法的电控喷油器磁路结构优化设计

以车用电控汽油喷油器为对象,从电磁学、机械动力学的基本原理出发建立了电控汽油喷油器工作过程的计算模型,依据通电后线圈电流的变化特点得出了动态响应特性与磁路结构参数的函数关系。以提高动态响应特性为目标,采用多目标模拟退火算法（MOSA）对磁路结构参数进行了优化。电磁场仿真结果表明,优化后的磁力线和磁感应强度分布更加合理。实验测试结果表明,优化后的汽油喷油器的开启延迟时间和关闭延迟时间分别比优化前缩短29.41%和29.23%。仿真和实验结果均验证了优化算法的有效性。     

喷油器有限元建模及结构动力学分析

采用UG建立喷油器模型,在AWB中进行模态分析和谐响应分析,得出了频率对喷油器共振影响最大的结果,喷油器的第7、8阶频率(2 800 Hz左右)是最容易引起喷油器共振的.     

喷嘴参数对柴油机喷油规律与性能的影响

采用广安博之(Hiroyasu)等准维模型,建立高原运行柴油机工作过程模型;基于一维非定常可压缩理论建立柴油机喷射系统模型,二者耦合计算高原环境喷油器主要结构参数对柴油机实际运行时的喷油规律、燃烧特性和输出性能的影响.台架试验验证了模型的可信性.结果表明:喷孔数和喷孔直径对喷油规律影响最为敏感,喷孔夹角对喷油规律影响微弱.在海拔4 000m时,针对该型柴油机,喷孔面积存在一个最优区间,在该区间给出了功率变化率和喷孔面积的关系式.在燃烧室结构和供油系统参数不变的情况下,当喷孔面积减小为原喷孔的25%～60%时,柴油机功率最大提升8.5%;油耗最大下降8.8%,排气温度下降35℃以上.但是缸内温度明显上升,NOx排放恶化.研究为通过优化喷油器参数改善高原运行柴油机燃烧和性能提供了参考.     

A mathematical model for the prediction of the injected mass diagram of a S.I. engine gas injector

A mathematical model of gaseous fuel solenoid injector for spark ignition engine has been realized and validated through experimental data. The gas injector was studied with particular reference to the complex needle motion during the opening and closing phases, which strongly affects the amount of fuel injected. As is known, in fact, when the injector nozzle is widely open, the mass flow depends only on the fluid pressure and temperature upstream the injector: this allows one to control the injected fuel mass acting on the “injection time” (the period during which the injector solenoid is energized). This makes the correlation between the injected fuel mass and the injection time linear, except for the lower injection times, where we experimentally observed strong nonlinearities. These nonlinearities arise by the injector outflow area variation caused by the needle bounces due to impacts during the opening and closing transients [1] and may seriously compromise the mixture quality control, thus increasing both fuel consumption and pollutant emissions, above all because the S.I. catalytic conversion system has a very low efficiency for non-stoichiometric mixtures. Moreover, in recent works [2, 3] we tested the simultaneous combustion of a gaseous fuel (compressed natural gas, CNG, or liquefied petroleum gas, LPG) and gasoline in a spark ignition engine obtaining great improvement both in engine efficiency and pollutant emissions with respect to pure gasoline operation mode; this third operating mode of bi-fuel engines, called “double fuel” combustion, requires small amounts of gaseous fuel, hence forcing the injectors to work in the non-monotonic zone of the injected mass diagram, where the control on air-fuel ratio is poor. Starting from these considerations we investigated the fuel injector dynamics with the aim to improve its performance in the low injection times range. The first part of this paper deals with the realization of a mathematical model for the prediction of both the needle motion and the injected mass for choked flow condition, while the second part presents the model calibration and validation, performed by means of experimental data obtained on the engine test bed of the internal combustion engine laboratory of the University of Palermo.