Variable area flowmeter based on H-shaped opening and arc parting line

Abstract

The variable area flowmeter based on the H-shaped opening and the arc parting line is characterized in that the variable area flowmeter comprises a pipeline assembly, a flexible thin film assembly and a pressure tapping connector; the pipeline assembly comprises a flowmeter upstream pipeline and a flowmeter downstream pipeline. The two ends of the pipeline assembly are the air inlet end and the air outlet end respectively. A circular diaphragm is placed in an upstream pipeline of the flow meter and is mounted in a direction perpendicular to the air flow direction; gas can only flow through the throttling opening area of the diaphragm; the flexible thin film assembly comprises a circular diaphragm; the pressure tapping interface comprises a flowmeter upstream pressure tapping hole and a flowmeter downstream pressure tapping hole; a flowmeter upstream pressure tapping hole and a flowmeter downstream pressure tapping hole are formed in the upstream position and the downstream position of the pipeline assembly respectively and matched with a pressure sensor to measure the static pressure difference before and after gas passes through the circular film. The gas flow sensor is simple in structure and convenient to process, and can realize low-pressure-loss, high-sensitivity and wide-range gas flow measurement.

Description

Technical Field

[0001] This invention belongs to the field of fluid measurement technology, specifically relating to a variable area flow meter based on an H-shaped opening and a circular arc dividing line. Background Technology

[0002] Lung function tests are the gold standard for diagnosing, assessing, and monitoring the treatment of chronic obstructive pulmonary disease (COPD). Currently, various flow meters are available on the market for monitoring patients' lung function. These devices can be broadly categorized into two types: one type barely interferes with fluid flow, such as ultrasonic flow meters and thermal mass flow meters; the other type introduces some disturbance to the fluid through throttling or pressure differentials, such as orifice plates, venturi tubes, or variable orifice flow meters.

[0003] The first type of equipment is typically complex in structure and expensive; the second type is simpler in structure and lower in cost, but it has some impact on the fluid. Differential pressure flow meters belong to the second type, and their performance directly affects the accuracy and reliability of the measurement. Among common differential pressure flow meters, fixed orifice plate flow meters suffer from significant permanent pressure loss and narrow measurement range due to their inherent structural limitations, making it difficult to meet the requirements of high-precision flow measurement. Although multi-pore balanced flow meters effectively reduce pressure loss through their distributed structure, their complex porous geometry brings prominent drawbacks such as high manufacturing difficulty, susceptibility to blockage by moisture and secretions in patients' exhaled air, and difficulty in thorough cleaning and disinfection, limiting their long-term stability and practicality in clinical environments.

[0004] This invention aims to solve the following series of technical problems existing in the application of existing differential pressure flow meters (especially fixed orifice plate and multi-orifice balanced flow meters) for pulmonary function testing:

[0005] (1) Existing fixed orifice plate flow meters rely on fixed orifice diameters to generate differential pressure, which results in a large permanent pressure loss when the airflow passes through, which is not conducive to low impedance measurement in respiratory detection.

[0006] (2) Existing fixed orifice plate flow meters have fixed orifice plate sizes that cannot be changed: when the orifice diameter is small, it will cause excessive differential pressure in the high flow velocity range, resulting in inaccurate measurement; when the orifice diameter is large, the differential pressure is insufficient in the low flow velocity range, and effective measurement cannot be achieved.

[0007] (3) Although existing multi-hole balanced flow meters can effectively reduce pressure loss and improve flow field based on fixed orifice plates, there is still a certain amount of permanent pressure loss. At the same time, since its throttling structure is composed of multiple small holes, some channels are prone to blockage or deposition, resulting in a reduction in gas flow area, which in turn affects measurement accuracy and long-term stability.

[0008] (4) The multi-bladed radial structure is subjected to concentrated force at high flow rates, which can easily lead to fatigue damage at the blade root. Summary of the Invention

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A variable area flow meter based on an H-shaped opening and an arc-shaped dividing line includes: a pipe assembly, a flexible diaphragm assembly, and a pressure tapping interface;

[0011] The pipeline assembly includes an upstream pipeline and a downstream pipeline of the flow meter, with the inlet and outlet ends of the pipeline assembly, respectively. A circular diaphragm is placed inside the upstream pipeline of the flow meter and is installed perpendicular to the airflow direction. Gas can only flow through the throttling opening area of ​​the diaphragm.

[0012] The flexible thin-film assembly includes a circular diaphragm having an H-shaped opening;

[0013] The pressure tapping interface includes: upstream pressure tapping port of the flow meter and downstream pressure tapping port of the flow meter; upstream and downstream pressure tapping ports of the flow meter are respectively set at the upstream and downstream positions of the pipeline assembly, and are used in conjunction with pressure sensors to measure the static pressure difference of gas before and after passing through the circular diaphragm.

[0014] The present invention has the following beneficial effects:

[0015] (1) The present invention forms an H-shaped symmetrical opening by cutting on a circular diaphragm. The opening area can be deformed by airflow, and the opening area changes with the pressure difference, which can reduce pressure loss.

[0016] (2) The present invention utilizes the automatic tilting characteristic of flexible film under the action of airflow pressure difference, so that the flow meter can actively adjust the channel cross-sectional area under different flow rates, ensuring linearity and wide dynamic measurement range.

[0017] (3) The present invention forms an H-shaped symmetrical opening structure by cutting on a circular diaphragm, and utilizes the variable flow area formed by the diaphragm automatically tilting up under the action of airflow, which avoids the problem of easy blockage of porous structures, and automatically increases the channel area under high flow rate to reduce permanent pressure loss.

[0018] (4) By introducing a circular arc dividing line design, the present invention effectively alleviates the stress concentration at the blade tip and can improve the service life of the flow meter. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the variable area flow meter based on the H-shaped opening and arc dividing line of the present invention.

[0020] Figure 2This is a schematic diagram of the internal structure of the variable area flow meter based on the H-shaped opening and the arc dividing line of the present invention, wherein 1-upstream pipe of the flow meter, 2-upstream pressure tap of the flow meter, 3-circular positioning ring, 4-circular retaining ring, 5-H-shaped opening diaphragm, 6-downstream pressure tap of the flow meter, and 7-downstream pipe of the flow meter.

[0021] Figure 3 This is a schematic diagram of an H-shaped opening diaphragm, where 5 is the H-shaped opening diaphragm, 8 is the spacing between blades, and 9 is a rectangular opening blade.

[0022] Figure 4 This is a schematic diagram of the structure of an inner arc H-shaped opening diaphragm, where 8 - the distance between blades, 10 - the inner arc H-shaped opening diaphragm, 11 - the inner tip arc dividing line, and 12 - the inner arc-shaped blade.

[0023] Figure 5 This is a schematic diagram of the structure of an outer arc H-shaped opening diaphragm, where 8 - the spacing between blades, 13 - the outer arc H-shaped opening diaphragm, 14 - the outer tip arc dividing line, and 15 - the outer arc-shaped blade;

[0024] Figure 6 The graph shows the actual experimental results (flow rate-differential pressure curve) of the inner arc H-shaped opening diaphragm. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0026] This invention provides a variable area flow meter based on an H-shaped opening and arc-shaped dividing lines. By cutting an H-shaped opening on a flexible diaphragm (i.e., a circular diaphragm) and introducing arc-shaped dividing lines at the inner or outer tip of the H-shaped opening, the circular diaphragm is partitioned and tilted under the action of airflow. This allows the channel cross-sectional area to be automatically adjusted according to the flow velocity, achieving high sensitivity at low flow velocities and low pressure loss at high flow velocities. At the same time, the arc-shaped dividing lines can effectively alleviate stress concentration at the opening end, improve the service life of the circular diaphragm, and reduce the risk of fatigue damage.

[0027] Depending on whether the circular diaphragm has an arc-shaped dividing line and the position of the arc-shaped dividing line, the technical solutions of the present invention include the following three types:

[0028] (1) Only H-shaped opening: H-shaped symmetrical window is cut on a circular membrane, which is divided into upper and lower opening areas;

[0029] (2) H-shaped opening structure with arc dividing line: an arc dividing line is introduced into the inner tip of the H-shaped opening;

[0030] (3) H-shaped opening structure with arc dividing lines at different positions: an arc dividing line is introduced at the outer tip of the H-shaped opening.

[0031] The variable area flow meter of the present invention, based on an H-shaped opening and an arc-shaped dividing line, includes:

[0032] Piping assembly: It consists of two pipes, upper and lower, connected to a circular diaphragm, used to allow gas to flow.

[0033] Flexible thin-film module: Gas passes through a circular diaphragm to generate a pressure difference, achieving a linear relationship between flow rate and differential pressure.

[0034] Pressure tapping interface: Located upstream and downstream of the circular diaphragm, the pressure difference between the two ends of the diaphragm can be obtained through a pressure sensor when airflow passes through. For example... Figure 1 , Figure 2 As shown, the present invention proposes a variable area flow meter based on an H-shaped opening and an arc dividing line, which consists of a pipe assembly, a flexible diaphragm assembly, and a pressure tapping interface.

[0035] The pipeline assembly includes an upstream pipeline 1 and a downstream pipeline 7, both made of polymer material and cylindrical in shape. The two ends of the pipeline assembly are the inlet and outlet, respectively. The upstream pipeline 1 contains a circular positioning ring 3 for holding a circular diaphragm. The diaphragm rests on the annular surface of the positioning ring 3, with its plane perpendicular to the airflow direction; that is, the normal direction of the diaphragm is aligned with the pipeline axis. The front end of the downstream pipeline 7 forms a convex annular section, a circular retaining ring 4, which engages with the positioning ring 3. During installation, the circular diaphragm is placed between the positioning ring 3 and the retaining ring 4, and the two engage tightly, fixing the diaphragm to the positioning ring 3. This ensures that gas can only flow through the throttling opening area of ​​the diaphragm. This structure guarantees the positioning accuracy of the diaphragm while facilitating disassembly and replacement.

[0036] The flexible thin-film assembly includes three types of circular diaphragms: an H-shaped opening diaphragm 5, an inner-arc H-shaped opening diaphragm 10, or an outer-arc H-shaped opening diaphragm 13. In practical use, each flowmeter of the present invention uses only one circular diaphragm. The circular diaphragm can be any of the three structures mentioned above, depending on design requirements; it can be an H-shaped opening diaphragm 5, an inner-arc H-shaped opening diaphragm 10, or an outer-arc H-shaped opening diaphragm 13. Although the different types of diaphragm structures differ slightly in shape, they all possess variable area throttling characteristics, enabling automatic adjustment of the flow area under airflow.

[0037] The upstream pipe 1 and the downstream pipe 7 of the flow meter are respectively equipped with a circular positioning ring 3 and a circular retaining ring 4, which are used to firmly fix the H-shaped opening diaphragm 5, the inner arc H-shaped opening diaphragm 10 or the outer arc H-shaped opening diaphragm 13 at the cross-section of the flow channel, so as to ensure that the airflow can only be transmitted through the throttling area of ​​the H-shaped opening diaphragm 5, the inner arc H-shaped opening diaphragm 10 or the outer arc H-shaped opening diaphragm 13 and will not leak from the edge.

[0038] The pressure tapping interfaces include: an upstream pressure tap 2 and a downstream pressure tap 6 for the flow meter. The upstream and downstream pressure taps 2 and 6 are respectively located upstream and downstream of the pipeline assembly, and are used in conjunction with pressure sensors to measure the static pressure difference of the gas before and after passing through the throttling element. The throttling element is any one of the circular films in the aforementioned flexible film assembly.

[0039] Flexible thin-film module design:

[0040] The H-shaped opening membrane 5, the inner arc H-shaped opening membrane 10, and the outer arc H-shaped opening membrane 13 are circular flexible films with an outer diameter of 28 mm, an inner diameter of 25 mm, and a thickness of 0.05 mm. The material used is polyethylene terephthalate (PET / Mylar) to ensure flexibility and biocompatibility. The circular flexible films are formed into different throttling opening structures through high-precision laser cutting.

[0041] H-shaped opening diaphragm 5: as shown Figure 3 As shown, the H-shaped diaphragm 5 has an H-shaped opening (the H-shaped opening itself is a symmetrical structure, located in the center of the H-shaped diaphragm 5). The slot in this H-shaped opening is called the blade spacing 8. The H-shaped opening divides the circular diaphragm into two independent blade units 9. Due to the blade spacing 8, only one end of the blade unit 9 is connected to the body of the H-shaped diaphragm 5, while the other three sides are free sides, thus creating a variable opening area under the action of airflow. At low flow rates, the gas mainly flows through the blade spacing 8; at high flow rates, the blade units 9 are blown up by the airflow and open to both sides, and the effective flow area increases with the increase of flow velocity, thereby achieving adaptive linearization of the flow rate-differential pressure relationship.

[0042] Inner arc H-shaped opening diaphragm 10: such as Figure 4 As shown, based on the H-shaped opening diaphragm 5, an arc dividing line is introduced at the inner tip of the blade spacing 8 (the horizontal inner position of the four ends of the H-shape), namely the inner tip arc dividing line 11, so that the opening end presents an inner arc transition structure, forming an inner arc blade 12, thereby reducing stress concentration under airflow impact and improving durability; at low flow rate, the gas mainly flows through the blade spacing 8; at high flow rate, the inner arc blade 12 is blown up by the airflow and opens to both sides, and the effective flow area increases with the increase of flow velocity, thereby realizing the adaptive linearization of the flow rate-differential pressure relationship.

[0043] Outer arc H-shaped opening diaphragm 13: such as Figure 5 As shown, based on the H-shaped opening diaphragm 5, an arc-shaped dividing line, namely the outer tip arc-shaped dividing line 14, is introduced at the outer tip of the blade spacing 8 (the horizontal outer position of the four ends of the H-shape). This creates an outer arc transition structure at the opening end, forming an outer arc-shaped blade 15. This optimizes the force distribution at the outer edge, making the automatic tilting process of the outer arc-shaped blade 15 smoother and further reducing fatigue damage. At low flow rates, the gas mainly flows through the blade spacing 8; at high flow rates, the outer arc-shaped blade 15 is blown up by the airflow and opens to both sides. The effective flow area increases with the increase of flow velocity, thereby achieving adaptive linearization of the flow rate-differential pressure relationship.

[0044] The aforementioned structure allows the flexible thin-film module to have a variable opening area. The flexible thin-film module can be quickly assembled by being pressed into the circular positioning ring 3 inside the pipe via a snap-fit ​​mechanism. The flexible thin-film module is a single flexible thin film with no redundant rigid support components, significantly reducing airflow resistance and manufacturing costs.

[0045] The working principle of this invention is as follows: Gas enters the variable area flow meter based on the H-shaped opening and arc-shaped dividing line from the upstream pipe 1, and obtains the upstream pressure value through the upstream pressure tap 2. Subsequently, the airflow acts perpendicularly on the H-shaped opening diaphragm 5, the inner arc H-shaped opening diaphragm 10, or the outer arc H-shaped opening diaphragm 13. At low gas flow rates, the H-shaped opening diaphragm 5, the inner arc H-shaped opening diaphragm 10, or the outer arc H-shaped opening diaphragm 13 remains almost closed, generating sufficient pressure difference only through a small gap: the blade spacing 8. As the flow rate increases, the opening area of ​​the H-shaped opening diaphragm 5, the inner arc H-shaped opening diaphragm 10, or the outer arc H-shaped opening diaphragm 13 gradually rises, the flow area increases accordingly, and the increase in pressure difference is limited, thereby achieving low impedance and wide range flow measurement. Finally, the gas is discharged from the downstream pipe 7 of the flow meter, and the downstream pressure value is measured through the downstream pressure tap 6 of the flow meter, which, together with the upstream pressure value, is used for flow calculation.

[0046] Figure 6 This is a graph showing the actual experimental results (flow rate-differential pressure curve) of the inner arc H-shaped opening diaphragm 10 of the present invention, from... Figure 6 As can be seen, the circular diaphragm of the present invention can adaptively adjust the flow cross section according to the flow rate, realizing an approximately linear mapping of flow rate and differential pressure across the entire range, thereby simultaneously improving low-velocity sensitivity and suppressing high-velocity pressure loss, significantly improving the dynamic range limitation of traditional differential pressure flowmeters.

[0047] The above description is merely an embodiment of the present invention and does not limit the scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related system fields, are similarly included within the protection scope of the present invention.

[0048] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A variable area flowmeter based on H-shaped opening and circular arc dividing line, characterized in that, The utility model relates to a pipeline assembly, a flexible film assembly and a pressure tapping interface. The pipeline assembly comprises a flowmeter upstream pipeline and a flowmeter downstream pipeline, and has an air inlet end and an air outlet end at two ends of the pipeline assembly; a circular diaphragm is arranged in the flowmeter upstream pipeline, and the circular diaphragm is installed perpendicularly to the direction of the air flow; the air can only flow through the throttling opening area of the diaphragm. The flexible film assembly comprises a circular diaphragm, and the circular diaphragm has an H-shaped opening. The pressure tapping interface comprises a flowmeter upstream pressure tapping hole and a flowmeter downstream pressure tapping hole; the flowmeter upstream pressure tapping hole and the flowmeter downstream pressure tapping hole are arranged at the upstream and downstream positions of the pipeline assembly respectively, and cooperate with a pressure sensor to measure the static pressure difference of the air before and after passing through the circular diaphragm. The flowmeter upstream pipeline and the flowmeter downstream pipeline are both made of a high polymer material and have a cylindrical structure.

2. The variable area flowmeter based on H-shaped opening and circular-arc segmentation line according to claim 1, characterized in that, The flowmeter upstream pipeline is provided with a circular positioning ring for placing the circular diaphragm; the circular diaphragm is placed on the annular surface of the circular positioning ring, and its plane is perpendicular to the direction of the air flow; the front end of the flowmeter downstream pipeline is provided with a circular clasp for interlocking with the circular positioning ring.

3. The variable area flowmeter based on H-shaped opening and circular-arc segmentation line of claim 1, wherein, During installation, the circular diaphragm is placed between the circular positioning ring and the circular clasp, and the circular positioning ring and the circular clasp are tightly interlocked by clamping to fix the circular diaphragm on the circular positioning ring, so that the air can only flow through the throttling opening area of the circular diaphragm.

4. The variable area flowmeter based on H-shaped opening and circular-arc segmentation line of claim 1, wherein, The circular diaphragm is an H-shaped opening diaphragm, an inner-arc H-shaped opening diaphragm or an outer-arc H-shaped opening diaphragm.

5. The variable area flowmeter based on H-shaped opening and circular-arc segmentation line of claim 1, wherein, The material of the H-shaped opening diaphragm, the inner-arc H-shaped opening diaphragm and the outer-arc H-shaped opening diaphragm is polyethylene terephthalate, and different throttling opening structures are formed by high-precision laser cutting.

6. The variable area flowmeter based on H-shaped opening and circular-arc segmentation line of claim 1, wherein, The H-shaped opening diaphragm is provided with an H-shaped opening, and the slot of the H-shaped opening is the blade spacing; the H-shaped opening divides the circular diaphragm into two independent blade units; only one end of the blade unit is connected with the H-shaped opening diaphragm body, and the other three edges are free edges; under the action of the air flow, the blade unit can produce a variable opening area.

7. The variable area flowmeter based on H-shaped opening and circular-arc segmentation line of claim 6, wherein, At low flow, the air mainly flows through the blade spacing; at high flow, the blade unit is blown up by the air flow and opens to both sides, and the effective flow area increases with the increase of the flow rate, thereby realizing the self-adaptive linearization of the flow-differential pressure relationship. The inner-arc H-shaped opening diaphragm introduces an internal tip circular arc division line at the internal tip of the blade spacing on the basis of the H-shaped opening diaphragm, so that the opening end part presents an inner-arc transition structure and forms an inner-arc blade; at low flow, the air mainly flows through the blade spacing; at high flow, the inner-arc blade is blown up by the air flow and opens to both sides, and the effective flow area increases with the increase of the flow rate, thereby realizing the self-adaptive linearization of the flow-differential pressure relationship.

8. The variable area flowmeter based on H-shaped opening and circular-arc segmentation line of claim 7, wherein, The outer-arc H-shaped opening diaphragm introduces an external tip circular arc division line at the external tip of the blade spacing on the basis of the H-shaped opening diaphragm, so that the opening end part presents an outer-arc transition structure and forms an outer-arc blade; at low flow, the air mainly flows through the spacing; at high flow, the outer-arc blade is blown up by the air flow and opens to both sides, and the effective flow area increases with the increase of the flow rate, thereby realizing the self-adaptive linearization of the flow-differential pressure relationship.

9. The variable area flowmeter based on H-shaped opening and circular-arc segmentation line of claim 7, wherein, ​ 10. The variable area flowmeter based on H-shaped opening and circular-arc segmentation line of claim 1, wherein, Gas enters the variable area flowmeter based on H-shaped opening and circular arc segmentation line from the upstream pipe, and the upstream pressure value is obtained through the upstream pressure tapping hole of the flowmeter. Then the gas acts vertically on the circular diaphragm. At low flow rate, the circular diaphragm almost maintains a closed state, and only a sufficient pressure difference is generated through the blade spacing. As the flow rate increases, the opening area of the circular diaphragm gradually rises, the flow area increases, and the pressure difference is limited. Finally, the gas is discharged from the downstream pipe of the flowmeter, and the downstream pressure value is measured through the downstream pressure tapping hole of the flowmeter, which is used for flow calculation together with the upstream pressure value.

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