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Abstract: To improve the measurement precision of flow rate characteristics of pneumatic components, a new measurement method is proposed, which is based on the dynamic regularity of instantaneous polytropic exponents during discharge. The dynamic regularity of polytropic exponents is obtained by the stop method, and it can be concluded as two change stages based on pressure time constant. According to piecewise polynomial fitting curves of instantaneous polytropic exponents, a new algorithm for the identification of flow rate characteristics is proposed. This method can accurately measure some components with a large sonic conductance and a small critical pressure ratio. Four pneumatic components are measured to compare the identification precision of those different methods. The results of comparison show that the new polytropic exponent method and its new algorithm have the higher precision than other alternative methods for the ISO6358 method. The identification errors of sonic conductance of the new method are less than 3%, and the identification errors of critical pressure ratio of the new algorithm are less than 15%. [Copyright &y& Elsevier]

In this paper, a new isothermal tank test circuit composed of two tanks and a new data-processing algorithm called Cbm method are proposed to measure the flow-rate characteristics of some pneumatic valves. The double-tank circuit is used to test some solenoid valves such as inner pilot solenoid, which the traditional isothermal discharge method can not apply to. And Cbm method changes the identification procedure of multivariable unconstrained optimal algorithm, which evidently improves the identification precision of critical pressure ratio and subsonic index. [ABSTRACT FROM AUTHOR]