Theoretical And Experimental Research On Compound Flowmeter

Flow measurement occupies a very critical role in the performance test of hydraulic systems and main hydraulic components.In the dynamic performance test of electro-hydraulic servo valve and proportional valve,the advantages of good dynamic performance and high natural frequency of the unloaded hydraulic cylinder are mainly used as a reference.However,due to the restriction of the piston stroke range,the unloaded hydraulic cylinder needs to be equipped with appropriate position control to achieve effective measurement of any offset flow.In view of this,this paper uses parallel metering pumps at both ends of the no-load hydraulic cylinder itself to realize the position adjustment of the piston.The measured flow is the sum of the flow through the no-load hydraulic cylinder and the metering pump.The structure design of the pump cylinder compound flowmeter not only gives full play to the good performance of the no-load hydraulic cylinder,but also solves the problem of measuring arbitrary offset flow.Based on the measuring principle of the compound flowmeter,the mathematical model of each measuring link of the compound flowmeter is established in this paper,and the measurement characteristics of the pump and hydraulic cylinder measuring flow are analyzed.The adjustment performance of the piston is simulated and analyzed.At the same time,a simulation model is built in Simulink to analyze the relationship between each measurement link and the total measured flow,and explore some main factors that affect the measurement performance of the composite flowmeter.Then the high frequency dynamic sinusoidal flow is measured and simulated in AMESim,and the simulation results show the reliability of the theoretical model analysis results.According to the main parameters,the leakage and compression flow are compensated by formula,and the error source of the measurement system is improved,which improves the measurement accuracy to a certain extent.In the experimental part of this paper,Lab VIEW software is used to build the test system platform to measure the step flow,high frequency sinusoidal flow and composite flow.The experimental results show that the dynamic sinusoidal flow measurement results follow the input signal well,and the flow measurement results of pump and hydraulic cylinder are in line with the simulation analysis conclusions,which effectively shows that the compound flowmeter has a good application prospect in dynamic flow measurement.