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CN-121977096-A - Pressure-independent fixed air valve and design method thereof

CN121977096ACN 121977096 ACN121977096 ACN 121977096ACN-121977096-A

Abstract

The invention discloses a pressure-independent air valve and a design method thereof, the pressure-independent air valve comprises a valve body with a tubular structure, a valve core shaft fixedly arranged in the valve body and concentrically arranged with the valve core shaft, a pre-tightening spring which is sleeved on the periphery of the valve core shaft in a sliding manner, one end close to an outlet of the valve body is fixedly connected with the valve core shaft and has adjustable pre-tightening force, a valve core which is slidably arranged on the periphery of the valve core shaft, is positioned on one side of the pre-tightening spring close to an inlet of the valve body and is pushed by extrusion of fluid force, and two baffles which are symmetrically arranged relative to the valve core shaft, are positioned on one side of the valve core close to the outlet of the valve body and are fixedly arranged in the valve body, wherein the valve core is of a hemispherical shell structure, and the arc convex surface of the valve core faces the inlet of the valve body. The invention can keep the constant flow in a wider pressure difference range under the condition of no external power, and can adjust the pressure difference range of the pressure-independent fixed air quantity valve by adjusting the precompression quantity of the precompression spring.

Inventors

  • QIAN HUA
  • Qiu Haoren
  • SHU ZHIYONG
  • ZHENG XIAOHONG

Assignees

  • 东南大学

Dates

Publication Date
20260505
Application Date
20260210

Claims (10)

  1. 1. A pressure-independent air valve is characterized by comprising a valve body (1) of a tubular structure, a valve core shaft (2) fixedly arranged inside the valve body (1) and concentrically arranged with the valve core shaft, a pre-tightening spring (3) fixedly connected with one end of the valve core shaft (2) close to an outlet (6) of the valve body (1) and adjustable in pre-tightening force, a valve core (4) slidably arranged on the periphery of the valve core shaft (2) and positioned on one side of the pre-tightening spring (3) close to an inlet (7) of the valve body (1) and pushed by fluid acting force, and two baffles (5) symmetrically arranged on one side of the valve core shaft (4) close to the outlet (6) of the valve body (1) and fixedly arranged inside the valve body (1), wherein the valve core (4) is of a hemispherical shell structure, the circular arc convex surface of the valve core (4) faces the inlet (7) of the valve body (1), a main flow (8) for fluid to pass through is arranged in the center position of the valve core (4), the main flow (8) is larger than the circular arc surface of the valve core (2) and directly passes through the secondary vent (8) along the circular arc of the valve core (2) and is arranged on the opposite circular arc surface of the main flow structure, a round rectangular vent hole for the main flow and the secondary flow after collision to pass through is formed between the two baffles (5).
  2. 2. The pressure-independent air valve according to claim 1, wherein a first nut (9) for adjusting the pretightening force of the pretightening spring (3) is arranged at one end of the valve core shaft (2) close to the inlet (7) of the valve body (1) in a threaded manner, and the valve core (4) is positioned between the first nut (9) and the pretightening spring (3).
  3. 3. The pressure-independent air valve according to claim 1, wherein a first shaft sleeve (10) for bearing the valve core shaft (2) is sleeved on the periphery of the valve core shaft (2), the first shaft sleeve (10) is positioned on one side of the pre-tightening spring (3) close to the outlet (6) of the valve body (1), and a plurality of first fixing supports (11) are fixedly connected between the first shaft sleeve (10) and the inner wall of the valve body (1).
  4. 4. The pressure-independent air valve according to claim 3, wherein the valve core shaft (2) is composed of a first shaft (12), a second shaft (13) and a shaft shoulder (14) fixedly connected between the first shaft (12) and the second shaft (13), the pre-tightening spring (3) is sleeved on the periphery of the first shaft (12), one end, close to the outlet (6) of the valve body (1), of the pre-tightening spring (3) is fixedly connected with the shaft shoulder (14), one end, close to the outlet (6), of the second shaft (13) is provided with a second nut (18) in a threaded manner, two first shaft sleeves (10) are located between the shaft shoulder (14) and the second nut (18), the first shaft sleeve (10), close to the inlet (7), is fixedly connected with the shaft shoulder (14), and the second nut (18) is abutted against the side, close to the outlet (6), of the other first shaft sleeve (10).
  5. 5. The pressure-independent air valve of claim 1, wherein a second sleeve (15) which is coaxially arranged with the main flow ventilation opening (8) is arranged in the valve core (4), a plurality of second fixing supports (16) which are distributed in an annular array are fixedly connected between the second sleeve (15) and the inner wall of the valve core (4), and the second sleeve (15) is sleeved on the periphery of the valve core shaft (2) in a sliding manner.
  6. 6. The pressure-independent air valve according to claim 1, wherein flanges (17) are arranged at two ends of the valve body (1).
  7. 7. A design method of a pre-tightening spring used in the pressure-independent air valve of any one of claims 1-6 is characterized by comprising the following steps, S1, constructing a three-dimensional simulation model of a pressure-independent fixed air quantity valve, and setting the starting pressure difference of the pressure-independent fixed air quantity valve And the maximum value of the critical position x Wherein the key position x refers to the shortest distance between the end face of the valve core (4) close to the outlet (6) of the valve body (1) and the baffle (5); S2, flow coefficient based on pressure independent type fixed air quantity valve Is fitted to the flow coefficient by defining and three-dimensional simulation model Functional relation to key position x ; S3, setting a value range of the key position x, and simulating the flow coefficient of the three-dimensional simulation model in the value range by adjusting the compression amount of the pre-tightening spring (3) To make flow coefficient Minimum value with maximum range as target to do critical position x ; S4, value range based on key position x And functional relationship Calculating the flow coefficient Is a range of values of (a) ; S5, the pressure-independent type air quantity valve passes through the target volume flow as Based on flow coefficient when control error is eta The definition type calculation of (1) obtains the actual maximum working pressure difference of the pressure-independent fixed air quantity valve ; S6, calculating the elasticity coefficient k and precompression amount of the pretension spring (3) based on the stress relation of the valve core (4) when the acting force of the fluid and the acting force of the pretension spring (3) are balanced And maximum compression amount 。
  8. 8. The method for designing a preload spring in a pressure independent constant volume valve as set forth in claim 7, wherein the flow coefficient in step S2 is Is defined as Wherein Q is the volume flow through the pressure independent type fixed air quantity valve, and the unit is ; Is the pressure difference between the inlet (7) and the outlet (6) of the pressure-independent fixed air valve, the unit is Pa, the ρ is the density of the fluid, and the unit is ; In units of (A) ; Fitting the flow coefficient in step S2 Functional relation to key position x The method comprises the following steps: setting the fluid density and the volume flow of the pressure-independent fixed air quantity valve; Setting a key position x by adjusting the compression amount of the pre-tightening spring (3); multiple adjustment of pressure-independent pressure difference between inlet (7) and outlet (6) of fixed air valve Flow coefficient of fluid passing through pressure independent type fixed air quantity valve under different pressure differences when simulation key positions x are the same Multiple groups of key position x-flow coefficients obtained under the current key position x The data set is taken as a set of fitting samples; Changing the key position x for a plurality of times, and repeating the previous step when changing the key position x each time to obtain a plurality of groups of fitting samples; Based on different critical positions x, different pressure differences The following multiple groups of fitting samples fit flow coefficients Functional relation with key position x, fitted functional relation Is that Wherein m and n are constant parameters, and are determined by the geometric shapes of the valve core (4) and the baffle (5).
  9. 9. The method of designing a preload spring in a pressure independent type air valve as set forth in claim 8, wherein the calculation formula of the control error η in step S5 is as follows Wherein The volume flow of the pressure-independent fixed air volume valve is set as the target volume flow The volume flow actually passing through; Actual maximum working pressure difference The calculation formula of (2) is 。
  10. 10. The method of designing a preload spring in a pressure independent constant volume valve as set forth in claim 9, wherein the force analysis is performed on the valve core (4) when the valve core (4) is in equilibrium, and the maximum value is taken when the key position x The compression amount of the pre-tightening spring (3) is the pre-compression amount At this time, the valve core (4) satisfies Wherein A refers to the projection area of the valve core (4) onto the bottom surface of the valve body (1); When the key position x takes the minimum value When the compression amount of the pre-tightening spring (3) reaches the maximum compression amount At this time, the valve core (4) satisfies And (2) and Based on 、 And Calculated to obtain ; Based on And Calculated to obtain ; Then 。

Description

Pressure-independent fixed air valve and design method thereof Technical Field The invention belongs to the technical field of fixed air quantity valves, and particularly relates to a pressure-independent fixed air quantity valve and a design method thereof. Background The pressure-independent fixed air valve is key equipment for guaranteeing the air quantity stability of the ventilation system, and has important application value in laboratories, operating rooms and large building environments with extremely high requirements on the air flow stability. The existing mainstream mechanical self-operated pressure independent type air valve mostly adopts an air bag and valve plate combined structure, but the adjustable pressure difference range is limited by the size of the air bag and the volume of the valve, and the wide-range regulation and control are difficult to realize under the condition of limited space. Furthermore, although the high-precision pressure-independent fixed air valve based on the Venturi effect has excellent performance, the problems of necking down the valve body, huge volume, high cost and the like exist, and the application is limited. Disclosure of Invention The invention aims at providing the pressure independent type air quantity valve with convenient pressure difference range adjustment, stable flow and large pressure difference range. The second object of the invention is to provide a design method of a pre-tightening spring in a pressure-independent fixed air quantity valve. The valve core is of a hemispherical shell structure, the arc convex surface of the valve core faces the inlet of the valve body, a main flow vent through which fluid passes is formed in the center position of the valve core, the diameter of the main flow vent is larger than that of the valve core shaft, the baffle is of an arc sheet-shaped structure and used for guiding secondary fluid passing along the arc convex surface of the valve core to reversely flow and collide with the main flow directly passing through the main flow vent, and a round rectangular vent hole through which the main flow and the secondary flow after collision collide is formed between the two baffles. Further, a first nut for adjusting the pretightening force of the pretightening spring is arranged at one end of the valve core shaft, which is close to the inlet of the valve body, in a threaded manner, and the valve core is positioned between the first nut and the pretightening spring. Further, a first shaft sleeve for bearing the valve core shaft is sleeved on the periphery of the valve core shaft, the first shaft sleeve is positioned on one side of the pre-tightening spring, which is close to the outlet of the valve body, and a plurality of first fixing brackets are fixedly connected between the first shaft sleeve and the inner wall of the valve body. Further, the valve core shaft is composed of a first shaft, a second shaft and a shaft shoulder fixedly connected between the first shaft and the second shaft, the pretightening spring is sleeved on the periphery of the first shaft, one end of the pretightening spring, which is close to the outlet of the valve body, is fixedly connected with the shaft shoulder, a second nut is threaded at one end of the second shaft, which is close to the outlet, two first shaft sleeves are positioned between the shaft shoulder and the second nut, the first shaft sleeve, which is close to the inlet, is fixedly connected with the shaft shoulder, and the second nut is abutted against the side surface, which is close to the outlet, of the other first shaft sleeve (10). Further, the inside of case is provided with the second axle sleeve that sets up with mainstream vent coaxial, fixedly connected with a plurality of annular array distribution's second fixed bolster between the inner wall of second axle sleeve and case, the second axle sleeve sliding sleeve is at the periphery of case axle. Further, flange plates are arranged at two ends of the valve body. Based on the same inventive concept, the invention also discloses a design method of the pre-tightening spring in the pressure-independent fixed air quantity valve, which comprises the following steps, S1, constructing a three-dimensional simulation model of a pressure-independent fixed air quantity valve, and setting the starting pressure difference of the pressure-independent fixed air quantity valveAnd the maximum value of the critical position xWherein the key position x refers to the shortest distance between the end face of the valve core, which is close to the outlet of the valve body, and the baffle; S2, flow coefficient based on pressure independent type fixed air quantity valve Is fitted to the flow coefficient by defining and three-dimensional simulation modelFunctional relation to key position x; S3, setting a value range of the key position x, and simulating the flow coefficient of the three-dimensional simulation model in the value range by adj