外文翻譯---利用基于計算機的測量系統(tǒng)對液壓泵的參數(shù)進行選擇的方法 英文

1、MEASUREMENT SCIENCE REVIEW, Volume 1, Number 1, 2001119MEASUREMENTS OF SELECTED PARAMETERS OF A HYDRAULIC PUMP BY MEANS OF A COMPUTER-BASED MEASURING SYSTEMTadeusz Zloto 1), Zygmunt Biernacki 2), Marek Kurkowski 2),1) I

2、nstitute of Machine Technology and Production Automation, Czestochowa Technical University, Al. Armii Krajowej 21, 42-200 Czestochowa, Poland, e-mail: zloto@itm.pcz.czest.pl 2) Institute of Electronics and Control System

3、s, Czestochowa Technical University, Al. Armii Krajowej 17, 42-200 Czestochowa, Poland, e-mail: biernac@el.pcz.czest.pl , marekekb@poczta.onet.plAbstract: The basic characteristic parame- ters of the pump operation are p

4、resented. The parameters are monitored by a computer-based measuring system at a hydraulic stand. The structure of the measuring system and the con- struction of the measuring converters applied in the system are describ

5、ed.1 INTRODUCTION Due to their important advantages, hyraulic drives and controls are commonly applied in a number of fields of mechanical engineering. The still increasing demand for hydraulic drives encourages research

6、 on new constructional solu- tions 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 me- chanical energy

7、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 whi

8、ch are the most often applied in high-pressure systems. The compact construction of multipis- ton pumps makes it possible to obtain higher efficiency per unit of volume. Because of that the weight of machines in which mu

9、ltipiston pumps are used may be lighter. In many respects, such as reliability, efficiency, energy saving and automation of industrial processes, the require- ments on pumps are increasing. Intensive re- search on the c

10、onstruction of pumps will cer- tainly bring about new developments.2 CHARACTERISTIC QUANTITIES OF THE PUMP OPERATION In a perfect pump, where no losses occur, the power given out by the driving engine is equal to the p

11、ower supplied to the system by the operat- ing agent, according to the formula: Nt = Mt · ω = Qt · ?p (1)where: Nt is the theoretical power Mt is the theoretical torque at the pump shaftω is the angular vel

12、ocity of the shaft ?p = p2 – p1 is the difference between forc- ing pressure p2 and suction pressure p1 It is known [4] that volumetric losses, which deteriorate the theoretical efficiency of pumps, result mostly from l

13、eakages of the operating agent from displacement chambers through gaps between displacement elements and the walls of chambers or body of the pump. Knowing volu- metric losses one may determine volumetric efficiency of t

14、he pump as a ratio of real flow intensity to theoretical flow intensity:n qQ 1 QQ QQQtsts ttrz v ? ? = ? = = η (2)The hydraulic-mechanical losses, on the other hand, cause the real torque applied to the pump shaft to be

15、greater than the theoretical torque. This kind of loss is associated with the flow resistance of the operating agent in the in- ternal channels of the pump as weel as with fric- tion losses occurring on the surface of al

16、l 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

17、loss torque. The real torque can be represented as a sum of the theo- retical torque and the loss torque: Mrz = Mt + Ms (3)The hydraulic mechanical efficiency of the pump is defined as:ts s ttrzt hmMM 11M MMMM+ = + = = η

18、 (4)Ultimately, the total efficiency ηc of the pump is equal to the ratio of the effective power to the power supplied to the pump shaft:MEASUREMENT SCIENCE REVIEW, Volume 1, Number 1, 2001121Fig.3. Schematic diagram of

19、 the inductive torque meter 1 – inductive converter with a Wheatstone bridge, 2 and 3 – rotational transformers? Flow intensity Q is measured by means of a measuring set consisting of a turbine converter and a counting

20、analog flow meter (Fig. 4). The angular velocity of the turbine rotor is theoreti- cally assumed as a linear function of intensity Q(t) of the flowing oil [2].Fig. 4. Schematic diagram of the measuring sys- tem of the t

21、ubine flow meter 1 –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 pre

22、ssures 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

23、converted into an electric signal by means of the piezoelectric sensor. Resistorsconnected in a bridge are diffused in a quartz plate. The pressure deforms the plate, the diffused resistors change their resistance

24、, 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 o

25、f the converter of pressure into current with a piezoresistive sensor 1 – feedback resistor, 2 – regulator of current powering the converter , 3 – amplifier, 4 – current regulator.The results of the measurements of the