Development And Experiment Of CAT System For Static And Dynamic Characteristics Of Electrohydraulic Proportional Directional Control Valve

The application of computer-aided test (CAT) provides a brilliant future for characteristic test of electro-hydraulic proportional directional control valves and the technology of virtual instrument brings CAT into a new developing stage. Based on the technology of virtual instrument, for the first time in this project experiment the static and the dynamic characteristic tests of electro-hydraulic proportional directional control valves are realized on the general hydraulic valve testing platform. The involved theories are data acquisition and processing, testing technology and testing signal processing, digital signal processing, automatic control, instruments and meters, hydraulic transmission, hydraulic proportional control, machine processing, virtual instrument. This project researches much deeper on the difficult problem of keeping the valve pressure difference steady during the testing of the flow characteristic of the electro-hydraulic proportional directional control valves. By using the VI technology, realizes the pressure difference feedback closed loop control system which is composed of PID adjustment and which makes the fluctuation of valve pressure difference within 5% during the testing of the flow characteristic. It makes the testing result more accurate. During the testing of load-flow characteristic, the LabVIEW program makes it stepping up that the control electric current of the proportional solenoid of the loading proportional relief valve. It is actualized that the continuous and automatic loading. By using this testing system, it is tested that the characteristics of DHZO-T-051-L5/Y electro-hydraulic proportional directional control valve produced by Atos Co., including the flow characteristic, the pressure gain characteristic, the load-flow characteristic, the flow-pressure difference characteristic, the frequency characteristic and the step response characteristic. The testing results are analyzed and the results of the test are correct. The software of the testing system is programmed in LabVIEW 5.11 which is used under Windows 2000. It can be widely used and each testing module is independent and no mutual interference. It owns friendly interface and is easy to be operated. All the stimulating signals are produced by the virtual signal sources and virtual instruments performs all the testing functions. This testing system predigests real instruments and the expenditure is reduced.