外文翻译---利用基于计算机的测量系统对液压泵的参数进行选择的方法.docx

附 录 三英文文献MEASUREMENT SCIENCE REVIEW, Volume 1, Number 1, 2001MEASUREMENTS OF SELECTED PARAMETERS OF A HYDRAULIC PUMP BY MEANS OF A COMPUTER-BASED MEASURING SYSTEMTadeusz Zloto 1), Zygmunt Biernacki 2), Marek Kurkowski 2), 1) Institute of Machine Technology and Production Automation,Czestochowa Technical University,Al. Armii Krajowej 21, 42-200 Czestochowa, Poland, e-mail:zlotoitm.pcz.czest.pl2) Institute of Electronics and Control Systems, Czestochowa Technical University,Al. Armii Krajowej 17, 42-200 Czestochowa, Poland,e-mail: biernacel.pcz.czest.pl , marekekbpoczta.onet.plAbstract: The basic characteristic parameters of the pump operation are presented. The parameters are monitored by a computer-based measuring system at a hydraulic stand. The structure of the measuring system and the construction of the measuring converters applied in the system are described.1 INTRODUCTION Due to their important advantages, hydraulic drives and controls are commonly applied in a number of fields of mechanical engineering.The still increasing demand for hydraulic drives encourages research on new constructional solutions intended to improve operating parameters, efficiency and to lower production cost.Each hydrostatic system has a displacement pump as a basic part. The pump changes mechanical energy into the energy of pressure of a liquid operating agent. Then, the latter kind of energy is transmitted to a hydraulic engine where it is changed back into mechanical energy.At present, it is axial multipiston pumps which are the most often applied in high-pressure systems. The compact construction of multipiston pumps makes it possible to obtain higher efficiency per unit of volume. Because of that the weight of machines in which multipiston pumps are used may be lighter. In many respects, such as reliability, efficiency, energy saving and automation of industrial processes, the requirements on pumps are increasing. Intensive research on the construction of pumps will certainly bring about new developments.2 CHARACTERISTIC QUANTITIES OF THE PUMP OPERATIONIn a perfect pump, where no losses occur, the power given out by the driving engine is equal to the power supplied to the system by the operating agent, according to the formula: (1)where:Nt is the theoretical power；Mt is the theoretical torque at the pump shaft； is the angular velocity of the shaft；p = p2 . p1 is the difference between forcing pressure p2 and suction pressure p1。It is known 4 that volumetric losses, which deteriorate the theoretical efficiency of pumps, result mostly from leakages of the operating agent from displacement chambers through gaps between displacement elements and the walls of chambers or body of the pump. Knowing volumetric losses one may determine volumetric efficiency of the pump as a ratio of real flow intensity to theoretical flow intensity: (2)The hydraulic-mechanical losses, on the other hand, cause the real torque applied to the pump shaft to be greater than the theoretical torque. This kind of loss is associated with the flow resistance of the operating agent in the internal channels of the pump as weel as with friction losses occurring on the surface of all the moving parts. Since it is difficult to differentiate between the losses resulting from the two sources mentioned above, they are considered jointly as hydraulic-mechanical efficiency, which may be expressed as the loss torque. The real torque can be represented as a sum of the theoretical torque and the loss torque: (3) The hydraulic mechanical efficiency of the pump is defined as： (4)Ultimately, the total efficiency of the pump is equal to the ratio of the effective power to the power supplied to the pump shaft: (5)After transformations the following was obtained： (6)Thus, the total pump efficiency is the product of volumetric efficiency and hydraulic mechanical efficiency.Fig. 1 presents the characteristic quantities necessary for determining the pump efficiency【4】。Fig. 1. Quantities characterizing pump operation3 COMPUTER MEASURING SYSTEM FOR THE PUMP OPERATION PARAMETERSThe use of computers in measuring systems and in control systems contributes towards the automation of measurements. It also improves the functioning of measuring systems by providing more sophisticated methods of data processing.Contemporary measuring devices based on microprocessor technology perform a number of functions, including measurements of diverse quantities. For monitoring the parameters of pump operation a computer measuring system has been developed. A block diagram of this system is presented in Fig. 2.The measuring system designed and constructed by the authors of the present paper includes a standard PC 5. It is intended for automatic handling of the experiment, in which data from various measuring converters is observed simultaneously and saved on the disc.Fig. 2. Block diagram of the measuring systemThe system displays large versatility. Its modular structure makes it possible to modify the measuring stand. The user may connect to any channel of the system a desired sensor of a physical quantity. Then a converter suitable for the sensor has to be installed in that channel.The system includes a unit consisting of a digital measuring system with a processor, collecting signals from the system of modules of converters, including converters of temperature, pressure, rotational velocity, flow intensity and torque. Each unit may contain up to 16 modules. It is connected by interface RS . 232 to a standard PC. The unit processor operates the modules and provides serial transmission with the computer. If interface RS . 485 is used instead, up to 31 units may be connected to the system. The operation of the system can be compared to that of a sampling oscilloscope.The efficiency factor of the axial multipiston pump is determined in the following way:The torque at the pump shaft is measured by means of an inductive torque meter Mi5 6. The measuring system of the inductive torque meter consists of a torque converter and an electronic measuring subsystem (Fig. 3).Fig.3. Schematic diagram of the inductive torque meter1 . inductive converter with a Wheatstone bridge, 2 and 3 . rotational transformersFlow intensity Q is measured by means of a measuring set consisting of a turbine converter and a counting analog flow meter (Fig. 4). The angular velocity of the turbine rotor is the oretically assumed as a linear function of intensity Q(t) of the flowing oil 2.Fig. 4. Schematic diagram of the measuring system of the tubine flow meter1 .inductive converter, 2 . rotor.The rotational velocity of the pump shaft and the engine is measured by counting the impulses sent by a magnetic disc converter situated at the engine shaft.The pressures p were measured by means of electronic membrane pressure sensors.A diagram of a pneumatic-electric converter, which functions as a manometer with an output electric signal is presented in Fig. 5. The pressure is converted into an electric signal by means of the piezoelectric sensor. Resistors connected in a bridge are diffused in a quartz plate. The pressure deforms the plate, the diffused resistors change their resistance, and the bridge loses the equilibrium. Subsequently, the output signal of the bridge is transformed in the electronic system into a current signal whose value is proportional to the measured pressure.Fig. 5. Diagram of the converter of pressure into current with a piezoresistive sensor1 . feedback resistor,2 . regulator of current powering the converter ,3 . amplifier,4 . current regulator.The results of the measurements of the pump operation parameters are displayed at the screen of the presented measuring system (Fig. 6).Fig.6. Graphic representation of the results during a change in the pump parameters4 CONCLUSIONSThe analyses of the results obtained in the experiment lead to the following conclusions:The parameters of the pump operation can be monitored online by means of the computer based measuring system.Apart from monitoring and displaying the results, the system makes it also possible to control the experiment.Standard measuring converters can be applied in the system for indirect assessment of the pump efficiency.The accuracy of the obtained results depends mainly on the metrological parameters of the intermediary systems, i.e. modules converting the measuring signals.REFERENCES1 Z. Biernacki: Sensory i systemy termoanemometryczne (Sensors and thermoanemometric systems). Wyd. Komunikacji I cznoci, Warszawa 1997.2 A. Balawender: Napdy hydrauliczne (Hydraulic drives). wyd. PG, Gdask 1983.3 W. Winiecki: Organizacja komputerowych systemw pomiarowych (Organization of computer-based measuring systems), wyd. Politechniki Warszawskiej, Warszawa 1998.4 S. Stryczek: Napd hydrostatyczny (Hydrostatic drive), WNT, Warszawa 1997.5 Instrukcja Faster Elektronic (Faster Electronic - users guide), Wrocaw 1995.6 Instrukcja momentomierza (Torque meter . users guide), IMR, Pozna 1990.英文文献译文测量科学研究，第一卷，1号，2001利用基于计算机的测量系统对液压泵的参数进行选择的方法Tadeusz Zloto , Zygmunt Biernacki , Marek Kurkowski ,琴斯托霍瓦技术大学机械技术和生产自动化研究所陆军21，42-200，琴斯托霍瓦，波兰，电子邮箱：zlotoitm.pcz.czest.pl琴斯托霍瓦技术大学电子和中央控制研究所陆军17，42-200，琴斯托霍瓦，波兰，电子邮箱：biernacel.pcz.czest.pl , marekekbpoczta.onet.pl摘要：对液压泵运行时的基本特征参数进行介绍，利用以计算机为基础的测量系统对液压站的参数进行监测，对测量系统的结构和应用于测量系统中的测量变换器进行描述。1. 简介由于液压在工业生产中具有重要的作用，因此液压驱动和控制广泛地应用于机械工程的各个领域，仍在不断增长的对液压驱动的需求量鼓励着人们在新的制造技术方面进行旨在提高运行参数、提高效率和降低生产成本低额的研究。每个液压系统都将容积泵作为它的一个基本组成部分，容积泵可以将机械能转化为流体运行机构的压力能，然后，这种压力能会被输送到可以将它再次转换成机械能的液压机器中去，目前，在高压系统中应用最多的是轴向柱塞泵，它紧凑的结构形式可以使人们有可能实现在每单位体积内获得更高的效率，也正是因为这个原因，应用柱塞泵的机器的质量有可能会变得更轻。人们对液压泵在可靠性、效率、节能和工业生产过程自动化等许多方面的要求还在不断的提高，对液压泵集约性制造的研究必将带来新的发展。2. 液压泵运行时的特征量在理想的液压泵中，系统驱动设备输出的能量等于动力机构提供给系统的能量，即在运行过程中没有能量的流失现象发生。这一原理所遵循的方程是： （1）其中：理论能量；泵轴的理论扭矩；轴的角速度；压油压力吸油压力之间的压力差。据了解4，容积损失将会使液压泵的理论效率变低，产生这一现象的原因是容腔中存在着泄漏现象，而泄漏主要产生于容积单元和腔壁或者泵体之间的缝隙。如果我们知道一个液压泵的体积容量损失，我们就可以得到实际流量和理论流量之比，并将其看作是液压泵的容积效率： （2） 另一方面，液压的机械损失将导致施加到泵轴的真正的扭矩要大于理论扭矩。这种能量损失和泵体运行机构内部通道的流体阻力有关系，就像在运动部件的所有接触面上都发生着摩擦损失一样。由于很难区分液压泵的损失到底来源于以上提到的两种情况中的哪一种，我们通常把他们共同看作是液压机械效率，并用扭矩损失来表示。真正的扭矩可以表示为理论扭矩和损失扭矩之和： （3） 泵的液压机械效率可以表示为： （4）最后，泵的总的机械效率等于有效功率和液压泵轴输入功率的比值： （5）等效变换以后我们可以得到以下公式： （6）因此液压泵的总的效率等于容积效率和机械效率的乘积。图1表示的是决定液压泵效率的必要特征量4。图1 液压泵运行时的特征量3. 泵运行参数的计算机测试系统计算机在测试系统和控制系统中的应用有助于实现测量过程的自动化，也有助于通过提出更精准的数据处理方法来改进测试系统的功能。基于微处理器技术的现代测量设备具有包括多种尺寸测量在内的多种功能。为了监测液压泵运行时的参数，人们已经成功的研制出计算机测试系统。计算机测试系统的框图如图2所示。该测试系统包括一台标准PC，并且是由本论文的作者进行设计和搭建的5。该系统主要用于实验的自动化处理，在这个过程中各种测量转换器中的数据被同步观测出来同时并保存在光盘上。图2 测量系统的方框图该测试系统是大型多功能系统，它的模块化结构使得它可以修改测量标准，用户可以连接到系统中任何一个信道所需