柴油机PT喷油器试验台的使用

我部研制的PT喷油器试验台可完成喷油量和密封性2个项目测试工作,是PT喷油器性能测试和故障检查的理想设备。该试验台主要由油路系统、气路系统、电控系统组成,由外接空气压缩机供气,外接电源供电,由电动机带动燃油泵供油。该试验台采用与发动机相同形状的凸轮,通过电动机、胶带传动装置及机械油压复合夹紧机构,模拟PT喷油器在发动机上的实际工作状态,运用光电燃油计量显示系统进行检测。     

HA290型PT喷油器试验台的供油稳压系统分析

为保证用于康明斯（Cummins）柴油机的PT喷油器在发动机上的工作性能，必须预先进行密封、雾化、流量等一系列试验。英制，HA290型PT喷油器试验台主要用来测量和校正各种PT喷油器在标定状况（包括进油压力、供油速率、油质等）下的喷油量，使其符合规范值。PT喷油器供油压力的变化直接影响到喷油量的变化。为保证恒定的供油压力，HA290型试验台采用了一种新颖、可靠的供油稳压系统（图1）。一、系统简介HA290试验台上，被试PT喷油器的供油压力标定为0．7MPa，但各种型号喷油器的喷油量从每次喷射90mm’到每次喷射500mm‘不等。要在…     

柴油机熄火困难的原因

一台TY220型推土机配用的康明斯NT855-C型柴油机,熄火时间长达40s,该机采用PT燃油系,熄火困难的原因应是燃油系统中喷油器计量孔前的油压偏高,超过了熄火油压。导致喷油器计量孔前的油压偏高的原因主要有以下4个方面。     

柴油机喷油升程的调整方法

<正>柴油机PT燃油系统的基本原理是根据燃油泵输出压力和喷油器进油时间控制循环供油量,以满足柴油机不同工况的需要。供油计量时间即喷油器计量室与油道接通的时间,而计量室量孔的关闭取决于柱塞的位置。喷油器喷油升程指的是喷油器柱塞由最高点压至最底部所经过的距离,它不     

液压缸微内漏检测试验台设计

该文利用液压油的可压缩特性,采用高精度手动补偿计量方式,将低压大流量变量泵和高压小流量定量泵有机结合,设计了液压缸微内漏检测试验台,给出了手动计量装置的关键参数计算方法。这对生产厂家检测液压缸的密封性能,特别是对液压缸微小内漏量的检测有积极意义。     

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。     

PT喷油器的调整方法

PT喷油器驱动机构如图1所示,调整的目的是使喷油器柱塞位于工作行程最下端对喷油器下端锥形罩作用一定压力,使燃油完全喷出,防止喷油量改变和残留燃油炭化堵塞喷孔。若此压力调整不当,将影响对燃油的准确计量和喷射,会导致燃油雾化不良,排放恶化,甚至压坏喷嘴,损坏机件。     

康明斯柴油机熄火困难的原因与排除

康明斯柴油机PT燃油系统是依靠电路系统中启动开关的关闭来熄火停机的。当启动开关旋至关闭位置后,柴油机应在7～10s内熄火,若熄火时间超过10s,则视为熄火困难。引起熄火困难的原因较多,但其实质则是燃油系统中喷油器计量孔前的油压偏高,超过熄火油压所致。常见导致喷油器计量孔前的油压偏高的原因有以下几点。     

新型国产电控喷油器动态特性分析及关键参数测量

介绍了电磁喷油器的工作原理和流量特性。从电路、磁路、机械运动和流体运动等多角度建立了一个综合的计算模型。在此基础上开发出电磁喷油器的检测台,以检测喷油器的滴漏、喷油量、喷油角度、雾化程度、喷油均匀度;在各工作环境中的工作状态;进行全过程自动静态检测、动态检测和选择检测,能模拟发动机任意工况,真实观察到喷油器工作的全过程。该检测系统已投入使用,取得了良好效果。     

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.     

一种电控喷油器动态时间参数测试方法

详细分析了电控喷油器的动态工作过程,基于电控喷油器线圈电流变化规律,提出一种测试其动态响应时间的方法。以高性能C8051F310单片机为处理器,设计了喷油器开启与关闭响应时间的测试电路,开发了成本低、测试便捷、精度高的测试系统。实测结果表明,喷油器的开启与关闭的响应时间测量误差分别为0.9%和1.14%,满足喷油器设计开发、生产的要求。同时,给出了开启响应时间随供电电压的变化关系曲线,该曲线为电控喷油器标定及发动机匹配时对喷油量的修正提供了参考。     

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。     

低压电控喷油器无效喷油时间测量方法

以低压电控喷油器的结构模型为基础,结合电磁场理论分析了喷油脉冲作用下衔铁组件的运动历程以及线圈电流的变化规律,证实了衔铁组件运动过程中,特征位置出现的时刻与线圈电流突变时刻的一致性。依此提出了一种针对无效喷油时间的非接触式测量方法,并应用单片机技术开发了一款测量系统。通过试验对比的方法对测量系统进行了验证：测量结果的绝对误差最大值为0.02ms,相对误差最大值为2.94%。     

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.     

降维测量微小位移的方法

论述了降维测量微小位移的原理,基于该原理,建立了微小位移降维测量系统,实现了用一线阵CCD接收器同时测量两维位移量这一测量方法,介绍了降维测量系统的组成、实现方法和检测结果。     

辉光放电质谱法相对灵敏度因子影响因素研究

本工作研究了辉光放电气体流速、放电电压和放电电流3个主要因素对辉光放电质谱法（GDMS）相对灵敏度因子（RSF）的影响。结果显示,在恒定的放电电流或放电电压下,重元素的RSF随放电气体流速的增大而增大,轻元素的RSF随放电气体流速的增加略微减小或不变;在恒定的放电气体流速下,多数元素的RSF基本不随放电电流和放电电压改变。在400 mL/min放电气体流速下,分别测定了Fe、Co、Ti、Ni、Zn、Sn、Pb 7种不同基体标准物质部分元素的RSF,结果显示,同一元素在不同基体条件下RSF的差异较小,基体效应不明显。将进一步得到的不同基体下的平均RSF应用于2种铜锌合金标准物质元素组分的测定,其主要元素的测定值与标准值的相对百分差均不超过30%。     

磨料浆体流针阀体研磨技术研究

提出了一种基于磨料浆体射流技术的针阀体喷孔研磨技术。该技术利用针阀体喷孔的节流作用使射流发生,靠浆料的研磨作用来去除针阀体内流道毛刺,对喷孔孔口进行倒角,以提高其流量系数。加工时,通过流量控制系统实时监测、控制针阀体的实时流量与终止流量,来控制其流量离散度。实际加工实验表明,该技术可以提高针阀体流量系数到0.85左右,同批针阀体流量离散度控制在±1%以下,达到国外同类技术的先进水平。     

Displacement measurement of the soil nail walls by using close range photogrammetry and introduction of CPDA method

Displacement measurement of the soil nail walls is a very important task in monitoring tiny movements in excavations to prevent disastrous accidents like wall collapsing. In building construction projects, this is usually done by either micro-geodesy or accurate instrumentation methods. In this research, for the first time, the use of close range photogrammetry in displacement measurement of the soil nail walls has been proposed and experienced. For this, a photogrammetric system was designed, implemented and evaluated. Proposed system with three separate methods for displacement measurement, which one of them was submitted for the first time (CPDA), was implemented. The evaluation results the accuracy of 3 mm is achievable in determining the point coordinates with a precision of 8 mm in displacement measurement of soil nail walls. Due to the efficiency, low cost, high accuracy, high speed of observations along with the simplicity of implementation of close range photogrammetry, it is suggested as a proper alternative to the traditional methods.     

低成本低功耗超声波热量表的研制

介绍基于单片机MSP430F4152和数字电位器MCP41010的超声波热量表设计方案。采用超声波时差法原理,以MCP41010构成增益可调的超声波回波信号放大电路,利用MSP430F4152实现流体流量和温度差的测量,既测量精度,又降低了成本和功耗。