1、外文资料翻译伺服阀试验台计算机辅助测试系统的研制Study on Computer Assistant Test System of ServoValve Test-bedAbstract：According to the need of the static and dynamic characteristics ofthe test on servo valve , firstly this article introduces the necessary part of the system-the pump station. Next, it designs the correspon
2、ding hydraulic and computer-aided test system and given the composition of software and hardware of the test system and the design process of software.In the end,we apply the designed system to actual production to prove that it achieve the requirements of the test on servo valve. Key words：servo va
3、lve, test rig, CAT, dynamic and static characteristics 1. Introduction Electro-hydraulic servo valve is the frequently-used control component in measurement and control system. Due to the wide use of electro-hydraulic servo system in metallurgy, engineering machinery, and chemical industry, a large
4、number of servo valves are also be applied in these industries.Affect by the facters of environmental，abrasion,aging and so on,servo valve will malfunction inevitably and need repairs after using a certain time.After maintenance and repair,we must detect the servo valve through some certain testing
5、methods of dynamic and static to decide whether its various properties meet the stipulated requirements or not. Thus,large enterprises establish independent servo valve test-bed according to the own needs.What is described below is a servo valve test-bed developed jointly by our unit and a universit
6、y and the test-bed is based on computer-aided testing. 2.Hydraulic pump stationHydraulic pump station also known as the pump station is an independent hydraulic device. It offers oil according to the requirements gradually and controlls the direction, pressure and flow rate of hydraulic oil, applied
7、 to the mainframe and hydraulic devices separability of hydraulic machinery. After the purchase users just connect hydraulic station and host of implementing agencies (motor oil or fuel tanks) with tubing, and hydraulic machinery can be realize these movements and the work cycle.Hydraulic pump stati
8、on consists of pump device, block or valve, tanks, a combination of electrical boxes.The function of each components are as follows:(1)Pump device is equipped with motors and pumps, is the source of power of the hydraulic station. It changes mechanical energy into hydraulic oil pressure energy.(2)In
9、tegration block is assembled by hydraulic valve and channel body. It can adjust the direction, pressure and flow of the hydraulic oil. (3)Valve portfolio plate valve is installed in the board and channels connect with each other after the board witch is the same as integration valve.(4)Tank plate is
10、 a welding semi-closed container, and also located with oil filtering network and air filters used for oil, oil filters and cooling.(5)Electrical boxes have two patterns. One designs external fuse terminal plate; The other installs a full range of electrical control.Hydraulic station principle: moto
11、r driven pump rotation, and pump absorbs oil from the oil tank and changes mechanical energy into hydraulic pressure energy of the station. Hydraulic oil through manifold (or valve combinations) realizes the adjusting of direction, pressure, flow .Then through external pipe to the cylinder hydraulic
12、 machinery or motor, so as to realize the changing of the direction , the size of the force and the velocity, to promote the machinery working of all kinds. 3. Hydraulic testing system and testing methods Test-bed can complete the test on static and dynamic characteristics of servo valve.Static char
13、acteristics of the test includes characteristics of unloaded flow, characteristics of pressure-gain, characteristics of flow-pressure and characteristics of leakage; dynamic characteristics are mainly the test on frequency characteristics of servo valve. The above testing results of characteristics
14、need to be drawn out in the way of graph. Figure 1 is a schematic diagram of hydraulic test system. According to the testing tems ,we install the valve to be tested on the static and dynamic testing board respectively.When we execute a static test, we should close the switching valve 8, and open the
15、 valve 6 .On the contrary, turn on valve 8 , and turn down valve 6 when we do a dynamic test. 3.1 Testing method of characteristics of unloaded flow Operations are as follows,when we test the characteristics of unloaded flow.First,close switch valve 18 and 7, and open valve 17 and 9.We should make s
16、ure the pressure difference between the two output ports A and B of the electro-hydraulic servo valve PL=0. And then input triangle-wave current signal with the frequency of 0.01Hz into the valve being tested. The size of the current signal vary in accordance with the following rule: changes from 0
17、to +imax, then from +imax to 0, then to +imax , and back to 0.Turbine flow meter 16 detects the flow in the process of the varying current and input the computer with the measured flow and corresponding current.The computer can draw the curve of the flow varing with the current,namely the curve of t
18、he unloaded flow characteristics q = f ( i) pL = 0. And according to the measured data ,we can calculate valve flow-gain, symmetry, zero-drift and hysteresis and other important properties of the valve. 3.2 Test method of load-flow characteristicsThe operations of the test on load-flow characteristi
19、cs are as follows: First, open switch valve 18 and 9, close the valves 17 and 7, make sure the oil of port A and B flows through the one-way valve 23 and proportional relief valve 22. Proportional relief valve (minimum moderating pressure 0.5MPa) can change the load pressure during the test,and the
20、turbine flowmeter 16 can measure the flow under a variety of load operating conditions. To start the test,we should adjust the relief valve 3, make sure the pressure of the system is the same as the rated pressure of the electro-hydraulic servo valve to be tested.Then input the valve coil being test
21、ed with a triangle-wave current signal of 0.01Hz,and then control the proportional relief valve 22 to make the load pressure change gradually from zero to the rated pressure by a certain increment and measure the flow under each increment and input into the computer at the same time. And then change
22、 the amplitude of the input current (frequency unchanged), repeat the above process,we can measure curves of more groups.This is the characteristic curve of the load flow of electro-hydraulic servo valve q = f ( PL) i = Cont.3.3 Test method of pressure characteristics Before the test, closed switch
23、valve 17,18 and 7 and open the valve 9, make sure the output flow of the valve to be tested is zero.Then adjust the pressure relief valve 3 so that the pressure of the system equals to the rated pressure and return oil pressure (measured by pressure sensor 13) . Then input the valve coil to be teste
24、d with a triangular wave current signal of 0.1Hz.The computer reads the value of pressure transducer 14 and 15,so we can detect the pressure difference of the two out port of the servo valve.Change the input current signal amplitude,and we can measure pressure value under different current amplitude
25、s.Pressure-gain curves can be sketched out,according to the value of current and pressure difference PL =f ( i) q =0.3.4 Testing method of leakage featuresClose switch valve 17,18 and 9,and open valve 7,then adjust the relief valve 3 to make the pressure of the system is the same as the rated pressu
26、re of the valve to be tested.Then input the valve coil with exciting current and measure the flow by flow transducer 5,and input the computer with the leak signal and rated exciting current signal after sampling. Leckage curves can be sketched out by the testing system qr = f ( i) .3.5 Test of dynam
27、ic characteristicsAccording to the international standard , test of dynamic characteristics of current servo valve mainly refers to width of amplitude frequency when characteristic curve of amplitude frequency is -3dB and phase-frequency width when characteristic curve of phase-frequency is -90.We s
28、hould use 10 sinusoidal signals of different frequiencies for exciting signals of the valve coil to be tested ,then measure the output flow signal in turn and filter out the signals different with the exciting signal of the flow signal and serve it as the response signals of the servo valve to be te
29、sted . The two signals are entered into the computer by turns after sampling , and epuate the auto-spectral spectrum of the exciting signals GXX(f) and cross-power spectrum of exciting signals and responding signals GXY(f) . By this method we can get the frequency response H (f) = GXX (f) / GXY (f)
30、. When we do the test of the dynamic characteristics , close switch valve 6 and open valve 8 . An independent signal generator produces scaning sinusoidal signal . The signal is entered into the servo amplifier after amplification and drive the dynamic cylinder to move . With the help of the speed s
31、ensor installed on the dynamic cylinder ,we can equate the output flow of the servo valve being tested . And the shift sensor installed on the other side can be used for preventing the dynamic cylinder from deviating from the central position . 4. Current circuit of the test system The signals need
32、to be collected during the static characteristics test of the testing system signals include Current signals of the servo valve coil to be tested, Pressure of inlet oil port , Pressure signal of load port A and B , Pressure signal of leaking mouth , Flow signal of load port A and B , Flow signal of
33、leaking mouth . The signals need to be collected during the dynamic characteristics test include current signals of valve coil to be tested ,Voltage signal outputed by speed sensor 20.Control signals outputed by the testing system include setting value of pressure of the proportional relief valve , Stimulating signals
