喷油器流量对非道路用小型柴油机燃烧和排放影响

为了研究喷油器流量对小型非道路柴油机燃烧过程及排放的影响,以某1115柴油机为研究对象,利用Hydism软件研究不同流量喷油器的喷油特性并进行整机性能和排放试验。结果表明:标定工况下,随着喷油器流量的增加,喷油速率峰值有所增加,喷油持续期略有缩短,瞬时放热率峰值和整机NO_X排放增加,但增幅减缓,燃油消耗率和烟度先减后增;中小负荷工况下,喷油器流量对整机CO和HC排放的影响较明显。因此需依据非道路柴油机排放测试要求匹配柴油机的喷油器流量,试验用柴油机匹配优化后,CO、HC和PM分别下降35.7%、45.1%和23.1%,NO_X上升8.9%,但HC+NO_X仍下降5.7%。结果表明合理匹配喷油器流量对小型非道路柴油机排放有较大影响,对小型柴油机满足排放标准是非常有效的技术措施。     

电控喷油器油量精确控制研究

在搭建的电控喷油器流量试验台上进行了喷油器流量特性试验,获得了不同条件下喷油器的流量特性,得到了影响喷油器喷油量的关键因素。通过建立喷油器电磁阀的数学模型,从电流响应的角度对试验现象进行了解释说明。在理论指导的基础上提出了双通道智能喷油器的设计方法,通过半物理仿真实验验证了设计思想的正确性,为解决喷油量精确控制的问题提出了一种新的思路。     

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。     

柴油机喷油器的选型试验研究

本文为了研究喷油器持续期与喷油落点对柴油机性能的影响,选取不同流量与不同喷射夹角的喷油器进行试验研究。研究结果表明,在相同外特性条件下,大流量喷油器在油耗和排温上有优势,烟度排放较差。另外,喷油器喷射夹角也是影响柴油机性能的重要参数。     

影响喷油器偶件流量的工艺研究

流量是喷油器偶件的一个重要性能指标,它直接影响柴油机的性能如油耗、烟度等,根据国家机械行业标准,喷油器偶件的最大和最小流量值一般要求控制在±3％以内。为了取得较好的产品质量,提高产品性能,就必须对喷油器偶件在制造加工过程中影响其流量的因素加以分析、研究。本文就是通过在现场生产实践中,对喷油器偶件的各种加工工艺进行分析,研究各中加工工艺对喷油器偶件流量的影响。     

响应曲面设计在电磁喷油器流量特性研究中的应用

本文在国内生产水平允许的范围内,基于响应曲面设计试验方法,以电磁喷油器的球阀最大升程、球阀组件质量、弹簧预紧力、喷孔总面积为影响因素,利用Design-Expert软件寻找静态流量和动态流量范围与关键结构参数的回归方程,为以后优化设计电磁喷油器的流量特性提供一种新的研究思路。     

共轨式喷油器高速电磁阀特性测试系统

高速电磁阀是共轨式喷油系统的关键部件，其特性直接影响柴油机共轨式燃油系统的性能。其静态特性反映了高速电磁阀的基本电磁特征，是进一步研究其动态特性的基础。介绍了共轨式喷油器高速电磁阀静态特性测试系统的总体结构及系统硬件和软件设计情况。利用所研制的测试系统对多种共轨式喷油器用电磁阀的静态特性进行测试，测试结果较好地反映了被测电磁阀的静态特性。通过对测试结果的分析，有助于发现电磁阀设计过程中出现的问题及其原因，对电磁阀的设计、改进很有帮助。     

基于CFD的柴油机多孔喷油器各孔内部流动特性差异研究

采用混合多相流空穴模型,进行喷孔轴线与针阀轴线夹角各异的多孔喷油器喷嘴内三维气液两相流数值模拟,详细研究多孔喷油器各孔内部流动特性的差异及喷油压力和喷油背压对其影响规律。结果表明:对于喷孔轴线与针阀轴线夹角各异的多孔喷油器,相同喷射条件下,随着喷孔轴线与针阀轴线夹角的增大,喷孔内的空化效应逐渐增强,质量流量和流量系数逐渐降低;随着喷油压力的提高,各孔内的空化效应均逐渐增强,质量流量均逐渐升高,流量系数均逐渐降低;随着喷油背压的提高,各孔内的空化效应逐渐减弱,质量流量逐渐降低,但流量系数却逐渐提高。     

基于STM32的汽车喷油器动态响应特性检测系统

为更加全面地检测汽车喷油器特性,开发了一种基于STM32的汽车喷油器动态响应特性检测系统。根据进气道式电压型喷油器的特点,设计并搭建了在线检测装置,研制了适用的喷油器的检测系统,能够有效采集喷油器的驱动电流曲线并精确测量其开启和关闭时间。在标准的测试环境下,通过对喷油器检测的实验表明,检测喷油器的动态响应相对误差小于2%,满足喷油器的检测要求,同时具有较高的稳定性。     

高压共轨喷油器测试电路设计及其检测平台开发研究

为了检测高压共轨喷油器的工作性能,改善汽车尾气的排放质量,对高压共轨喷油器的动作原理及其检测波形进行了分析,并对喷油器的喷油量进行了计算。采用PLC技术,利用PWM方法,设计了一种喷油器检测电路及其测试平台,可以检测各类型号的高压共轨喷油器在怠速及全油门状态下的喷油状况,对其喷油质量给出判定,该平台也可进行喷油嘴驱动电路的优化研究。     

超高压大流量比例插装阀测试方法

针对超高压大流量比例插装阀测试技术问题，以DN130位移随动式超高压大流量二通比例插装阀为对象，考虑该阀测试需针对超高压（70 MPa）、大流量（8 000 L/min）的特殊工作要求，设计了超高压试验台和高压大流量试验台。根据行业测试标准制定耐压特性和动静态特性测试方法，试验台流量无法满足测试需求时，采用基于模型的仿真预测方法进行性能检测。试验结果表明了该阀具有良好的耐压性能、流量增益特性、滞环特性、线性度特性、重复精度特性以及动态特性，为超高压大流量比例插装阀的设计测试提供了工程基础。     

Model-based optimization of injection strategies for SI engine gas injectors

A mathematical model for the prediction of the mass injected by a gaseous fuel solenoid injector for spark ignition (SI) engines has been realized and validated through experimental data by the authors in a recent work [1]. The gas injector has been studied with particular reference to the complex needle motion during the opening and closing phases. Such motion may significantly affect the amount of injected fuel. When the injector nozzle is fully open, the mass flow depends only on the upstream fluid pressure and temperature. This phenomenon creates a linear relationship between the injected fuel mass and the injection time (i.e. the duration of the injection pulse), thus enabling efficient control of the injected fuel mass by simply acting on the injection time. However, a part of the injector flow chart characterized by strong nonlinearities has been experimentally observed by the authors [1]. Such nonlinearities may seriously compromise the air-fuel mixture quality control and thus increase both fuel consumption and pollutant emissions (SI engine catalytic conversion systems have very low efficiency for non-stoichiometric mixtures). These nonlinearities arise by the injector outflow area variation caused by needle impacts and bounces during the transient phenomena, which occur in the opening and closing phases of the injector. In this work, the mathematical model previously developed by the authors has been employed to study and optimize two appropriate injection strategies to linearize the injector flow chart to the greatest extent. The first strategy relies on injection pulse interruption and has been originally developed by the authors, whereas the second strategy is known in the automotive engine industry as the peak and hold injection. Both injection strategies have been optimized through minimum injection energy considerations and have been compared in terms of linearization effectiveness. Efficient linearization of the injector flow chart has been achieved with both injection strategies, and a similar increase in injector operating range has been observed. The main advantage of the pulse interruption strategy lies on its ease of implementation on existing injection systems because it only requires a simple engine electronic control unit software update. Meanwhile, the peak and hold strategy reveals a substantial lack of robustness and requires expressly designed injectors and electronic components to perform the necessary voltage commutation.     

隔膜蓄能器瞬时流量仿真及试验

针对隔膜蓄能器提供较大瞬时流量以稳定系统压力的功用,以电控柴油机液压伺服系统隔膜蓄能器为研究对象,搭建了瞬时流量测试平台,建立了数学模型。基于AMESim软件平台建立了瞬时流量特性仿真模型进行仿真,并在测试系统上进行了瞬时流量试验,仿真与试验结果基本吻合。最后分析了蓄能器关键参数对瞬时流量特性的影响,其结果对于电控柴油机液压伺服系统的设计具有一定的指导意义。     

Intermittent airblast atomization and spray particle mixing in pulsating air flow

A new twin-fluid injector applicable to a single-point injector for gasoline engine was developed. Using this injector's transient spray characteristics, the mixing mechanism of spray particles and the deposition mechanism on the inner wall of an intake manifold were investigated. The measurements of spray particle sizes, velocities and deposition rates were experimentally conducted in a pulsating air flow. The particle deposition takes place due to the particle inertia at high air flow rates. At low air flow rates it comes due to the recirculation appearing on the inner wall at the entrance of the intake manifold. On the other hand, the deposition rate of spray particles is strongly influenced by air pulsation. The behavior of spray particle is mainly influenced by air pulsation when the velocity of the atomizing air is low and when the velocity of the air flow around the injector is high. Single small particles follow the air flow more easily than large particles, and this causes the spatial particle size distribution in the spray clump. As the spray particles approach to the tip of a spray clump, the size of particles.     

Effects of needle response on spray characteristics in high pressure injector driven by piezo actuator for common-rail injection system

The common-rail injection systems, as a new diesel injection system for passenger car, have more degrees of freedom in controlling both the injection timing and injection rate with the high pressure. In this study, a piezo-driven injector was applied to a high pressure common-rail type fuel injection system for the control capability of the high pressure injector’s needle and firstly examined the piezo-electric characteristics of a piezo-driven injector. Also in order to analyze the effect of injector’s needle response driven by different driving method on the injection, we investigated the diesel spray characteristics in a constant volume chamber pressurized by nitrogen gas for two injectors, a solenoid-driven injector and a piezo-driven injector, both equipped with the same injection nozzle with sac type and 5-injection hole. The experimental method for spray visualization was based on back-light photography technique by utilizing a high speed framing camera. The macroscopic spray propagation was geometrically measured and characterized in term of the spray tip penetration, spray cone angle and spray tip speed. For the evaluation of the needle response of the above two injectors, we indirectly estimated the needle’s behavior with an accelerometer and injection rate measurement employing Bosch’s method was conducted. The experimental results show that the spray tip penetrations of piezodriven injector were longer, on the whole, than that of the solenoid-driven injector. Besides we found that the piezo-driven injector have a higher injection flow rate by a fast needle response and it was possible to control the injection rate slope in piezo-driven injector by altering the induced current.     

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.     

Using momentum flux measurements to determine the injection rate of a commercial Urea Water Solution injector

The Selective Catalytic Reduction (SCR) technology allows the transformation of the Nitrous Oxide emissions present in exhaust gases into gaseous nitrogen and water. For a proper operation of the SCR, a urea-water solution (UWS) injector must dose an adequate amount of liquid into the exhaust pipe in order to avoid deposit formation and to guarantee the SCR system efficiency. This task requires the knowledge of the performance of the injector. Then, the goal of this work is to study the hydraulic performance of a UWS injector, by means of measuring the spray momentum flux in order to understand the influence of different variables as injected fluid, injection pressure, counter pressure and cooling temperature of the injector on the flow characteristics. The tested injector was cooled at three different temperatures, 60, 90 and 120 °C, the injection pressure of the UWS was set at 5, 7 and 9 bar, with counter pressures of 750, 900, 1000 and 2000 mbar for the two tested fluids, water and UWS. The measurements were carried out using an experimental facility developed at CMT-Motores Térmicos for the determination of spray momentum flux, where a piezoelectric pressure sensor was located near the nozzle exit of the injector, which measures the impact force of the spray. Additionally, the proposed methodology allowed to determine the injected mass flow and to capture the transient injection events, such as the opening and closing stages. Moreover, mass flow rate measurements of the injector were performed under the same operating conditions, determining the influence of the injection pressure, cooling temperature, counter pressure and fluid properties. Regarding the pressure, the tendency was as expected, the higher the injection pressure the higher the Momentum flux and flow rate. Results showed that an increment of the cooling temperature of the injector induces the appearance of flash boiling conditions, having an impact on the total injected mass and momentum flux, changing the behaviour of the spray. For the same conditions, water has a higher momentum flux than the UWS due to differences in fluid properties and velocity at the nozzle exit.     

一种气体燃料电控喷射系统的流量控制研究

针对气体燃料电控喷射系统对气体燃料喷射量的控制精度低以及流量实时连续调节等问题,提出一种基于电磁直线执行器直接驱动菌形阀的燃料电控喷射系统。在MATLAB/Simulink下建立整个系统的控制模型,仿真计算喷射装置在不同升程下的流量特性,同时对其内部的流场进行仿真,研究其在不同的供气压力下的稳态流量。仿真结果表明,系统的流量和喷射装置的升程以及供气压力成近似线性关系。因此可以通过控制升程的大小来实现流量的连续调节,搭建了气体燃料电控喷射系统的流量特性测试试验台。试验测试在升程分别为1~4 mm和供气压力0.02~0.05 MPa时的流量特性,和仿真结果相吻合,验证了模型的正确性,同时为燃料电控喷射系统的应用提供理论基础。     

汽油发动机电控喷油器结构改进设计

为进一步提高汽油发动机电控喷油器的性能,建立了喷油器工作过程的数学模型,分析了影响喷油器电磁响应特性的关键因素,对喷油器核心运动件即衔铁-球阀组件的结构进行了改进设计,改进后喷油器运动件质量减少10％.通过有限元分析软件分析验证表明,结构改进后能够保持喷油器电磁力基本不变,并能满足耐久性要求.对比试验测试结果表明,由于运动件质量减少,改进后的喷油器开启与关闭滞后时间与原喷油器相比分别缩短11％和8％,动态响应性能得到了提高.