A modeling method for equivalent orifice throttling area of pneumatic amplifier of regulating valve

Abstract

A kind of regulating valve pneumatic amplifier small hole equivalent orifice area modeling method belongs to regulating valve mechanism modeling technical field.It includes the following steps:1, the obtained pneumatic amplifier small hole equivalent orifice area S e Expression;2, obtain S e -t curve;3, obtain the resultant external force F-t curve suffered by pneumatic amplifier;4: S e -t curve and F-t curve are fitted, and F-S e Curve is obtained, and F-S e Curve is input into regulating valve mechanism model, and is verified.The present application starts from the structure and working principle of typical pneumatic amplifier, and is equivalent to a straight-through double-seat regulating valve and the physical model of adjustable orifice small hole flow, by the relationship between the resultant external force F and small hole equivalent orifice area S e It is designed as the nonlinear relationship of S e =f (F) form, which can better simulate the dynamic characteristics of pneumatic amplifier in the exhaust process.

Description

Technical Field

[0001] This invention belongs to the field of regulating valve mechanism modeling technology, specifically relating to a method for modeling the equivalent throttling area of ​​the orifice of a regulating valve pneumatic amplifier. Background Technology

[0002] In modern industry, especially in process control, the requirements for control speed, accuracy, and reliability are increasingly stringent. Pneumatic amplifiers, as both common independent electrical accessories for control valves and key components of valve positioners, have attracted considerable attention from researchers both domestically and internationally. Internationally, Azbil Corporation of Japan invented a high-performance pneumatic amplifier that can accelerate output pressure stabilization without increasing the discharge volume; Siemens of Germany invented a piezoelectric pneumatic amplifier with a simple structure and easy implementation. Domestically, rapid pneumatic amplifiers that effectively increase air supply flow, reduce transmission time, and improve the response and action speed of control valves, as well as new diaphragm-type pneumatic amplifiers with high reliability and versatility, have also emerged.

[0003] Despite the increasing variety of pneumatic amplifiers, there has never been a precise, universal pneumatic amplifier model, nor has there been a way to accurately establish the equivalent throttling area S of the orifice in a pneumatic amplifier. e Modeling is a crucial step in perfecting the simulation model of a control valve.

[0004] Starting with the typical structure and working principle of a pneumatic amplifier, it can be equivalent to a physical model of a straight-through double-seat regulating valve with adjustable orifice flow rate. This invention studies the equivalent orifice throttling area S through experimental methods. e This important parameter establishes the relationship between the net external force F of the aerodynamic amplifier and the equivalent throttling area S of the orifice. e The relational model. Summary of the Invention

[0005] In view of the above-mentioned problems in the prior art, the purpose of this invention is to provide a method for modeling the equivalent throttling area of ​​the orifice of a pneumatic amplifier for regulating valves, which can better simulate the dynamic characteristics of the pneumatic amplifier during the exhaust process.

[0006] This invention provides the following technical solution:

[0007] A method for modeling the equivalent throttling area of ​​the orifice in a pneumatic amplifier for a control valve is proposed, establishing the equivalent throttling area S of the orifice in the pneumatic amplifier. e The Simulink simulation model corresponding to the net external force F yields S. e The -t and Ft curves and the relationship between them; specifically including the following steps:

[0008] Step 1: Obtain the equivalent throttling area S of the pneumatic amplifier orifice based on the mass flow mechanism model of the pneumatic amplifier. e expression;

[0009] Step 2: Construct an experimental setup based on a pneumatic amplifier, air tank, and I / P converter to conduct a step experiment, collect and process the experimental data, and utilize the S obtained in Step 1. e The expression is used to establish a simulation model and obtain S. e -t curve; the step signal used here can more intuitively show the dynamic characteristics of the pneumatic amplifier's charging and discharging process, which is convenient for research;

[0010] Step 3: Based on the experimental data collected in Step 2 and the working state expression of the pneumatic amplifier, establish a simulation model and obtain the resultant external force Ft curve of the pneumatic amplifier.

[0011] Step 4: Apply the S obtained in Step 2 e The -t curve is fitted with the Ft curve obtained in step 3 to obtain FS. e Curve, FS e The mechanism model of the curve input regulating valve was verified.

[0012] Furthermore, the specific process of step 1 is as follows:

[0013] Step 1.1: The pressure model of the gas tank is represented as follows:

[0014] PV0 = nR0T0

[0015] m = nM0

[0016] get:

[0017]

[0018] In the formula, constants M0, V0, T0, and R0 represent the molecular weight of compressed air, the volume of the gas tank, the room temperature, and the gas constant, respectively; variables P, m, and n represent the gas tank pressure, the mass of compressed air, and the number of compressed air molecules, respectively.

[0019] Step 1.2: The mass flow mechanism model of the pneumatic amplifier is represented as follows:

[0020]

[0021] In the formula, q m That is P1 is the pressure upstream of the orifice, P2 is the pressure downstream of the orifice, θ1 is the air temperature upstream of the orifice, and b is the ratio of critical pressures.

[0022] Step 1.3: Based on Step 1.1 and Step 1.2, obtain information about S. e The expression:

[0023]

[0024] In the formula And

[0025] Further, the working state expression of step 3 is as follows:

[0026]

[0027] In the formula, P b is the control signal air pressure (back pressure), P in is the input air source pressure, P out is the air tank pressure, S1 is the effective area of the upper diaphragm, S2 is the effective area of the middle diaphragm, S3 is the effective area of the lower diaphragm, and S4 is the effective area of the valve core.

[0028] Further, the specific process of step 3 is as follows:

[0029] According to the experimental acquisition of the air source pressure P in , the air tank pressure P out , and the diaphragm area of the pneumatic amplifier, the control signal air pressure (back pressure) P b is calculated, and the diaphragm area, P b , P in , P out and the same simulation current signal input step 3 in the simulation model are obtained. The resultant force F-t curve of the pneumatic amplifier is obtained.

[0030] By using the above-mentioned technology, compared with the prior art, the beneficial effects of the present application are as follows:

[0031] The present application starts from the typical structure and working principle of the pneumatic amplifier, and equivalent to a straight-through double-seat regulating valve and a physical model of adjustable orifice flow. By designing the relationship between the resultant force F and the equivalent orifice area S e of the small hole as a nonlinear relationship in the form of S e =f(F), the dynamic characteristics of the pneumatic amplifier during the exhaust process can be better simulated. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a schematic block diagram of the experimental device of the present application;

[0033] Figure 2 is a simulation effect diagram of the output air pressure after the F-S e curve obtained by using the present application. DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be given to the present application in combination with the drawings and examples in the specification. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0035] On the contrary, the present application covers any substitution, modification, equivalent method and solution defined by the claims within the essence and scope of the present application. Further, in order to make the public have a better understanding of the present application, some specific details are described in the following detailed description of the present application. The present application can also be completely understood without the description of these details by those skilled in the art.

[0036] Please refer to Figures 1-2 A modeling method for equivalent orifice throttling area of a regulating valve pneumatic amplifier, specifically comprising the following steps:

[0037] Step 1: According to the S e expression obtained from the general mass flow mechanism model of the pneumatic amplifier, the S e expression is obtained.

[0038] Step 1.1: The pressure model of the gas tank is as follows:

[0039] PV0=nR0T0

[0040] m=nM0

[0041] The following is obtained:

[0042]

[0043] In the formula, the constants M0, V0, T0 and R0 are the molecular weight of compressed air, the volume of the gas tank, the room temperature and the gas constant respectively; the variables P, m and n are the gas tank pressure, the compressed air mass and the compressed air molecular number respectively.

[0044] Step 1.2: The mass flow mechanism model of the pneumatic amplifier is as follows:

[0045]

[0046] In the formula, q m is the aforementioned

[0047] Step 1.3: According to step 1.1 and step 1.2, the expression about S e is obtained:

[0048]

[0049] In the formula and:

[0050]

[0051] Step 2: According to Figure 1 The schematic diagram of the experimental setup shown illustrates the construction of the experimental setup and the conduct of a step jump experiment. Data is collected using a data acquisition device pre-installed on the experimental setup. The data is processed and the S obtained in step 1 is utilized. e The expression is used to build a Simulink simulation model and obtain S. e -t curve.

[0052] Step 2.1: Specific Step Experiment Design:

[0053] Step jump: 0-100-0-100-0;

[0054] Pin: 400 kPa; repeat the experiment three times to ensure good data repeatability and prevent the data from being random.

[0055] Step 2.2: The signal acquired in the experiment is the gas pressure P of the gas tank. out As S in step 1.3 e In the expression, P1 is taken as atmospheric pressure, and P2 is taken as atmospheric pressure. The parameters of the experimental environment at that time were measured: V0 = 8.5 × 10⁻⁶. -3 m 3 M0 = 29 g / mol, T0 = T (current temperature in °C) + 273.15 K Input the Simulink simulation model from step 2 into each input, run the simulation to obtain S e -t curve.

[0056] Step 3: Based on the experimental data collected in Step 2 and the working state expression of the pneumatic amplifier obtained from previous research in this laboratory, establish a Simulink model and obtain the resultant external force Ft curve of the pneumatic amplifier.

[0057] The working state model of the pneumatic amplifier is as follows:

[0058]

[0059] In the formula, P b To control the signal air pressure (back pressure), P in To input the gas source pressure, P out S1 represents the gas pressure in the gas tank, S2 represents the effective area of ​​the upper diaphragm, S3 represents the effective area of ​​the lower diaphragm, and S4 represents the effective area of ​​the valve core. The gas pressure P is based on the experimentally collected gas source pressure. in Gas cylinder pressure P out The area of ​​each diaphragm in the pneumatic amplifier, according to P b S1-(P out S3+P inThe control signal air pressure (back pressure) P is calculated according to the formula: (S2-S3)=0 b The film area, P b , P in , P out and the same simulation current signal input step 3 of the Simulink simulation model, the resultant aerodynamic amplifier F-t curve of the external force is obtained.

[0060] Step 4: S e -t obtained in step 2 is fitted with F-t obtained in step 3 using Matlab CurveFittingToolBox, taking F as the abscissa and S e as the ordinate, to obtain the F-S e nonlinear curve, which is input into the regulating valve mechanism model, the same input signal as in step 2.1 is given in the simulation, the simulation is run, and the simulation tank air pressure and the tank air pressure collected in the experiment are plotted as shown in Figure 2 , which can better simulate the dynamic process of the aerodynamic amplifier, especially during exhaust.

[0061] This embodiment establishes the relationship between the equivalent orifice area S e of the aerodynamic amplifier and the resultant external force F, and designs the relationship between them as a nonlinear relationship in the form of S e =f(F), which, compared with the traditional proportional relationship S e =kF, can better simulate the dynamic process of the aerodynamic amplifier, especially during exhaust, and is more in line with the actual situation.

[0062] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for modeling the equivalent throttling area of ​​the orifice in a pneumatic amplifier for a regulating valve, characterized in that: Establish the equivalent throttling area S of the orifice in the aerodynamic amplifier. e The simulation model corresponding to the resultant external force F yields S. e The -t and Ft curves and the relationship between them; specifically including the following steps: Step 1: Obtain the equivalent throttling area S of the pneumatic amplifier orifice based on the mass flow mechanism model of the pneumatic amplifier. e The expression; the specific process of step 1 is as follows: Step 1.1: The pressure model of the gas tank is represented as follows: PV0 = nR0T0 m = nM0 get: In the formula, constants M0, V0, T0, and R0 represent the molecular weight of compressed air, the volume of the gas tank, the room temperature, and the gas constant, respectively; variables P, m, and n represent the gas tank pressure, the mass of compressed air, and the number of compressed air molecules, respectively. Step 1.2: The mass flow mechanism model of the pneumatic amplifier is represented as follows: In the formula, q m That is P1 is the pressure upstream of the orifice, P2 is the pressure downstream of the orifice, θ1 is the air temperature upstream of the orifice, and b is the ratio of critical pressures. Step 1.3: Based on Step 1.1 and Step 1.2, obtain information about S. e The expression: In the formula and Step 2: Construct an experimental setup based on a pneumatic amplifier, air tank, and I / P converter to conduct a step experiment, collect and process the experimental data, and utilize the S obtained in Step 1. e The expression is used to establish a simulation model and obtain S. e -t curve; Step 3: Based on the experimental data collected in Step 2 and the working state expression of the pneumatic amplifier, establish a simulation model to obtain the resultant external force Ft curve of the pneumatic amplifier; the working state expression of Step 3 is as follows: In the formula, P b To control the signal air pressure, P in To input the gas source pressure, P out S1 is the gas pressure of the gas tank, S2 is the effective area of ​​the upper diaphragm, S3 is the effective area of ​​the middle diaphragm, S4 is the effective area of ​​the lower diaphragm, and S5 is the effective area of ​​the valve core. Step 4: Apply the S obtained in Step 2 e The -t curve is fitted with the Ft curve obtained in step 3 to obtain FS. e Curve, FS e The mechanism model of the curve input regulating valve was verified.

2. The method for modeling the equivalent throttling area of ​​the orifice in a pneumatic amplifier for a regulating valve according to claim 1, characterized in that... The specific process of step 3 is as follows: Based on the gas source pressure P collected in the experiment in Gas cylinder pressure P out The area of ​​each diaphragm in the pneumatic amplifier is used to calculate the control signal air pressure P. b The area of ​​each membrane, P b P in P out The same simulation current signal is input into the simulation model in step 3 as in the experiment, and the resultant external force Ft curve of the pneumatic amplifier is obtained.

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