Fluid flow calculation method and differential pressure flow sensor

Abstract

The present application relates to a fluid flow calculation method and a pressure differential flow sensor. A first front face and a second front face are placed obliquely in a fluid at different inclination angles. The fluid flow rate can be decomposed into a tangential component parallel to the front face and a normal component perpendicular to the front face. When calculating the pressure on the front face, the static pressure ρgh due to the weight of the liquid can be eliminated. When calculating the forward fluid pressure differential, the unknown constant C in the Bernoulli equation can be eliminated. The first back face and the second back face are placed obliquely in the fluid at different inclination angles. The reverse fluid pressure differential can be calculated. The forward fluid flow rate can be obtained based on the fluid density, the angle between the front face and the fluid flow direction, and the forward fluid pressure differential. Similarly, the reverse fluid flow rate can be obtained. The net flow rate per unit time can be obtained by accumulating the forward and reverse fluid flow rates per unit time. The present application eliminates the influence of complex factors, simplifies calculation formulas, and improves measurement accuracy.

Description

Technical Field

[0001] The present application relates to the technical field of flow sensors, and in particular to a differential pressure flow sensor. Background Art

[0002] There are numerous flowmeters on the market today, each based on a different set of physical principles, resulting in varying performance and pricing. Among these, orifice plate flowmeters, target flowmeters, and vortex flowmeters, which are based on fluid dynamics principles, are also considered by many companies when selecting flowmeters. The following focuses on orifice plate flowmeters and target flowmeters.

[0003] 1. Orifice flowmeter

[0004] The principle of an orifice flowmeter is to place a throttling device in a pipe. As the fluid in the pipe passes through the throttling device, the pipe diameter decreases, increasing the flow rate. This creates a pressure difference between the upstream and downstream pressures. According to Bernoulli's theorem, this pressure difference can be used to calculate the flow rate, or the rate of change of flow. This is then converted into a flow rate value over a period of time using an integrator, which is then displayed on the instrument or LED.

[0005] The advantage of the orifice flowmeter is that it is the only flowmeter approved by the International Standards Organization that does not require actual flow calibration, has no moving parts, is applicable to a wide range of fluid types (including gas and liquid), and is relatively inexpensive.

[0006] The disadvantages of orifice flowmeters are that the measurement accuracy is affected by many factors and is difficult to improve, the pressure loss is large, the measuring range is very narrow (3:1 to 4:1), and the measurement accuracy is difficult to maintain.

[0007] 2. Target flowmeter

[0008] The principle of a target flowmeter is to place a flow blocker (the "target") in the center of a pipe. When the fluid encounters the blocker during movement, it drives the blocker in the direction of flow. When this movement is blocked by a sensor-related structure, a pressure value is generated by the pressure sensor. Due to the momentum theorem, the relationship between pressure and fluid velocity can be determined. The flow rate over a period of time can be calculated from the instantaneous flow rate, thus completing the flow measurement.

[0009] The advantages of the target flowmeter are that it uses a dry calibration method (i.e., the weight hanging method) and the calibration is relatively convenient. It also has no moving parts, is applicable to a wider range of fluid types (including gas and liquid, high temperature and low temperature), has a small pressure loss (50% of the standard orifice plate), the sensor does not come into contact with the liquid, is corrosion-resistant, resistant to high and low temperatures, and is easy to maintain.

[0010] The disadvantages of target flowmeters are that the measurement accuracy is difficult to improve, the measuring range is narrow (10:1), the zero point must be reset each time the target is replaced, it is not suitable for applications that require frequent switching, and the target may fall off due to improper operation.

[0011] In summary, both orifice flowmeters and target flowmeters have the problem of difficulty in improving their accuracy. Summary of the Invention

[0012] In order to eliminate the influence of complex factors, simplify the calculation formula, and improve the measurement accuracy, the present application provides a fluid flow calculation method and a pressure differential flow sensor.

[0013] This application provides a method for calculating fluid flow and adopts the following technical solutions:

[0014] In one aspect, a method for calculating fluid flow rate comprises the following steps:

[0015] Providing a test body, wherein the test body has a first flow-facing surface, a second flow-facing surface, a first back-flow surface, and a second back-flow surface, all of which are planar;

[0016] The test body is fixed in the test piece, so that the first front face, the second front face, the first back face and the second back face are located at positions with the same fluid flow rate, so that the forward flow direction of the fluid is toward the first front face and the second front face, and the fluid can continue to flow forward along the first front face and the second front face; the fluid flow direction is away from the first back face and the second back face, and the fluid can continue to flow forward along the first back face and the second back face; a first angle between the first front face and the fluid flow direction and a second angle between the second front face and the fluid flow direction are obtained, the first angle and the second angle are not equal and are both acute angles, a first pressure on the first front face and a second pressure on the second front face are obtained, and a forward fluid pressure difference between the first front face and the second front face is obtained; based on Bernoulli's theorem and the principle of forward impact of a micro-liquid column on a target plate, a forward fluid flow rate V is calculated according to the first angle, the second angle and the forward fluid pressure difference. 正 ;

[0017] Obtain a third angle between the first backflow surface and the fluid flow direction, and a fourth angle between the second backflow surface and the fluid flow direction, wherein the third angle and the fourth angle are not equal and are both acute angles, obtain a third pressure on the first backflow surface and a fourth pressure on the second backflow surface, and obtain a reverse fluid pressure difference between the first backflow surface and the second backflow surface; based on Bernoulli's theorem and the principle of forward impact of a microfluid column on a target plate, calculate the fluid reverse flow velocity V according to the third angle, the fourth angle, and the reverse fluid pressure difference. 反 ;as well as,

[0018] By accumulating the forward flow Q within the time T(t1, t2) 正 and reverse flow Q 反 , calculate the net flow within the time range T(t1, t2).

[0019] By adopting the above technical solution, the first oncoming surface is tilted so that the angle between it and the fluid flow direction is an acute angle, and the fluid flow velocity can be decomposed into a tangential component parallel to the first oncoming surface and a normal component perpendicular to the first oncoming surface; the tangential pressure generated by the tangential component of the fluid on the first oncoming surface can be calculated based on the Bernoulli theorem in fluid dynamics, and the normal pressure generated by the normal component of the fluid on the first oncoming surface can be calculated based on the principle of the positive impact of the micro-liquid column on the target plate; the pressure exerted on the first oncoming surface is the sum of the tangential pressure and the normal pressure, which can eliminate the static pressure ρgh caused by the weight of the liquid and improve the calculation accuracy.

[0020] Similarly, the pressure on the second oncoming surface can be calculated using the same method mentioned above. Therefore, the pressure difference between the first oncoming surface and the second oncoming surface is the difference between the two pressures. This can eliminate the unknown constant C in the Bernoulli equation, further simplifying the calculation formula and improving the calculation accuracy.

[0021] The forward fluid pressure difference is related to the fluid density, the forward fluid flow rate, the first angle and the second angle. Therefore, the forward fluid flow rate can be calculated based on the fluid density, the first angle, the second angle and the forward fluid pressure difference; similarly, the reverse fluid pressure difference is related to the fluid density, the fluid reverse flow rate, the third angle and the fourth angle. The fluid reverse flow rate can be calculated based on the fluid density, the third angle, the fourth angle and the reverse fluid pressure difference; the net flow rate per unit time can be obtained by accumulating the forward fluid flow rate and the fluid reverse flow rate per unit time.

[0022] Optionally, the first oncoming surface and the second oncoming surface are perpendicular to each other, and the angles between them and the fluid flow direction are θ1 and θ2 respectively. The pressure difference between the first and second flow-facing surfaces is

[0023] By adopting the above technical solution, the first angle and the second angle are complementary to each other, which can further simplify the calculation formula of the positive fluid pressure difference and improve the measurement accuracy.

[0024] Optionally, the first backflow surface and the second backflow surface are perpendicular to each other, and the angles between them and the fluid flow velocity are θ2 and θ3 respectively. The pressure difference between the first backflow surface and the second backflow surface is

[0025] By adopting the above technical solution, the third angle and the fourth angle are complementary to each other, which can further simplify the calculation formula of the reverse fluid pressure difference and improve the measurement accuracy.

[0026] Optionally, the first oncoming surface and the second oncoming surface are perpendicular to each other, and the angles between them and the fluid flow direction are θ1 and θ2 respectively. The first backflow surface and the second backflow surface are perpendicular to each other, and the angles between them and the fluid flow velocity are θ2 and θ3 respectively. θ1=θ2.

[0027] By adopting the above technical solution,

[0028] Optional,

[0029] Forward fluid flow rate Fluid forward flow Fluid reverse flow rate Fluid reverse flow The net flow in the time range T(t1, t2) is

[0030] By adopting the above technical solution, the calculation of cos2θ1 and cos2θ2 is eliminated, the calculation formula is simplified, and the angles θ1 and θ2 between the sensor and the fluid flow direction are adjusted during installation. As long as the angles θ1 and θ2 are accurately controlled during detection, the measurement accuracy can be improved.

[0031] Optionally, obtain the maximum forward fluid velocity V max , the positive fluid pressure difference between the first oncoming surface and the second oncoming surface, then θ1=θ2<arccos((2 / 3)· / ρV max 2 ) / 2.

[0032] By adopting the above technical solution, by adjusting the angles θ1 and θ2 between the sensor and the fluid flow direction during installation, the measuring range can be almost infinitely amplified, thereby improving the measuring range.

[0033] In a second aspect, the present application also relates to a differential pressure flow sensor, comprising:

[0034] A test body, the test body having a first flow-facing surface, a second flow-facing surface, a first back-flow surface, and a second back-flow surface, all of which are planes; a pressure sensor is mounted on the first flow-facing surface for detecting a first pressure applied to the first flow-facing surface; a pressure sensor is mounted on the second flow-facing surface for detecting a second pressure applied to the second flow-facing surface; a pressure sensor is mounted on the first back-flow surface for detecting a third pressure applied to the first back-flow surface; a pressure sensor is mounted on the second back-flow surface for detecting a fourth pressure applied to the second back-flow surface; and,

[0035] a single-chip microcomputer electrically connected to each of the pressure sensors, and configured to obtain a first angle between the first frontal surface and the fluid flow direction, a second angle between the second frontal surface and the fluid flow direction, a third angle between the first back-flow surface and the fluid flow direction, a fourth angle between the second back-flow surface and the fluid flow direction, a fluid density, a first pressure, a second pressure, a third pressure, and a fourth pressure; wherein the first angle and the second angle are not equal and are both acute angles, and the third angle and the fourth angle are not equal and are both acute angles, and the single-chip microcomputer calculates the forward fluid flow velocity V according to the first angle, the second angle, the first pressure, the second pressure, and the fluid density. 正 ; According to the third angle, the fourth angle, the third pressure, the fourth pressure and the fluid density, the fluid reverse flow velocity V is calculated 反 According to the forward fluid flow rate V 正 and the fluid reverse flow velocity V 反 , calculate the forward flow Q within the cumulative time T(t1, t2) 正 and reverse flow Q 反 , and obtain the net flow within the time range T(t1, t2).

[0036] By adopting the above technical solution, the first frontal surface and the second frontal surface are placed obliquely at positions with the same fluid flow rate, so that the first angle and the second angle are not equal and are both acute angles, so that the pressure exerted on the first frontal surface is different from the pressure exerted on the second frontal surface, forming a pressure difference.

[0037] The fluid flow rate can be decomposed into a tangential component parallel to the first oncoming surface and a normal component perpendicular to the first oncoming surface. The tangential pressure exerted by the tangential component of the fluid on the first oncoming surface can be calculated using Bernoulli's theorem in fluid dynamics. The normal pressure exerted by the normal component of the fluid on the first oncoming surface can be calculated using the principle of the forward impact of a micro-liquid column on a target plate. The pressure exerted on the first oncoming surface is the sum of the tangential pressure and the normal pressure, which can eliminate the static pressure ρgh caused by the weight of the liquid and improve the calculation accuracy.

[0038] Similarly, the pressure on the second oncoming surface can be calculated using the same method mentioned above. Therefore, the pressure difference between the first oncoming surface and the second oncoming surface is the difference between the two pressures. This can eliminate the unknown constant C in the Bernoulli equation, further simplifying the calculation formula and improving the calculation accuracy.

[0039] The forward fluid pressure difference is related to the fluid density, the forward fluid flow rate, the first angle and the second angle. Therefore, the forward fluid flow rate can be calculated based on the fluid density, the first angle, the second angle and the forward fluid pressure difference; similarly, the reverse fluid pressure difference is related to the fluid density, the fluid reverse flow rate, the third angle and the fourth angle. The fluid reverse flow rate can be calculated based on the fluid density, the third angle, the fourth angle and the reverse fluid pressure difference; the net flow rate per unit time can be obtained by accumulating the forward fluid flow rate and the fluid reverse flow rate per unit time.

[0040] Optionally, the first oncoming surface and the second oncoming surface are perpendicular to each other.

[0041] By adopting the above technical solution, the first angle and the second angle are complementary to each other, which can further simplify the calculation formula of the positive fluid pressure difference and improve the measurement accuracy.

[0042] Optionally, the first back flow surface and the second back flow surface are perpendicular to each other.

[0043] By adopting the above technical solution, the third angle and the fourth angle are complementary to each other, which can further simplify the calculation formula of the reverse fluid pressure difference and improve the measurement accuracy.

[0044] Optionally, the first oncoming surface and the second oncoming surface are perpendicular to each other, and the angles between them and the fluid flow direction are θ1 and θ2 respectively. The first backflow surface and the second backflow surface are perpendicular to each other, and the angles between them and the fluid flow velocity are θ2 and θ3 respectively. θ1=θ2.

[0045] By adopting the above technical solution, the calculation of cos2θ1 and cos2θ2 is eliminated, the calculation formula is simplified, and the angles θ1 and θ2 between the sensor and the fluid flow direction are adjusted during installation. As long as the angles θ1 and θ2 are accurately controlled during detection, the measurement accuracy can be improved.

[0046] Optionally, it includes a shell, which has four contact surfaces connected end to end in the circumferential direction, and the four contact surfaces are the first upstream surface, the second upstream surface, the first downstream surface and the second downstream surface, respectively, and the single chip computer is located outside the shell.

[0047] By adopting the above technical solution, the overall integration is improved, and the distances between the first front flow surface, the second front flow surface, the first back flow surface and the second back flow surface are reduced, so that the forward fluid flow rate at the positions of the first front flow surface and the second front flow surface is kept consistent, and the reverse fluid flow rate at the positions of the first back flow surface and the second back flow surface is kept consistent, thereby improving the metering accuracy.

[0048] Optionally, every two adjacent contact surfaces are perpendicular to each other.

[0049] By adopting the above technical solution, under the premise that the surface area of the first frontal surface is constant, compared with the non-perpendicularity between the first frontal surface and the adjacent back surface, each two adjacent contact surfaces are perpendicular, which can reduce the volume of the sensor and achieve overall miniaturization.

[0050] Optionally, a mounting portion is provided on the housing, and the mounting portion is used to be connected to the inner wall of the test piece.

[0051] By adopting the above technical solution, the stability of the sensor in real-time pressure detection in the fluid is guaranteed, and the measurement accuracy is improved.

[0052] Optionally, the single chip microcomputer is connected to a DTU remote transmission receiving device, and the DTU remote transmission receiving device is used to communicate with the Internet of Things platform protocol and send pressure data and flow data to the Internet of Things platform.

[0053] By adopting the above technical solution, pressure data and flow data can be sent to the IoT platform for storage and display.

[0054] Optionally, the pressure sensor includes a corrugated diaphragm, silicone oil and a chip; the first upstream surface, the second upstream surface, the first downstream surface and the second downstream surface are all provided with mounting grooves, the chip is connected to a piezoresistor and a Huygens circuit, the chip is installed in the mounting groove, the chip is connected to the single-chip microcomputer, the corrugated diaphragm is installed on the first upstream surface, the second upstream surface, the first downstream surface and the second downstream surface, and the silicone oil is filled between the chip and the chip.

[0055] By adopting the above technical solution, the pressure sensor is a piezoresistive pressure sensor with high frequency response, small size, low power consumption, high sensitivity and good precision, and can measure to an accuracy of 0.1%.

[0056] In summary, this application includes at least one of the following beneficial technical effects:

[0057] 1. By tilting the first front face, the second front face, the first back face and the second back face, i.e., all angles are acute, the fluid velocity V can be decomposed into a tangential component V parallel to the front face / back face. t and the normal component V perpendicular to the upstream / reverse surface n, eliminating the static pressure ρgh caused by the weight of the liquid and improving the calculation accuracy.

[0058] 2. By making the inclination angles of the first frontal surface and the second frontal surface different, and the inclination angles of the first back surface and the second back surface different, the forward fluid pressure difference and the back fluid pressure difference can be calculated, eliminating the unknown constant C in the Bernoulli equation, further simplifying the calculation formula and improving the calculation accuracy.

[0059] 3. The first frontal surface and the second frontal surface are perpendicular, and the first back surface and the second back surface are perpendicular, which further simplifies the positive fluid pressure difference Δp 正 and the reverse fluid pressure difference Δp 反 The calculation formula can improve the measurement accuracy.

[0060] 4. The angle between the first frontal surface and the fluid flow direction is The angle between the first back-flow surface and the fluid flow direction is The calculation of cos2θ1 and cos2θ3 is eliminated, the calculation formula is simplified, and the calculation accuracy is improved.

[0061] 5. Differential pressure flow sensors inherit the advantages of flow meters based on fluid dynamics principles, such as orifice plate flow meters and target flow meters, while also avoiding some of their disadvantages, such as corrosion and dirt resistance, no need for zero setting, support for frequent switching, and fixed components that are not prone to falling off. At the same time, they achieve overall miniaturization and reduce pressure loss, making them suitable as pre-installed flow sensor components in intelligent pipe networks. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 is a schematic diagram of the calculation method in Example 1 of the present application;

[0063] Figure 2 It is a schematic diagram of the principle of forward impact of micro-liquid column on target plate;

[0064] Figure 3 This is a schematic diagram of the calculation method in Example 2 of the present application;

[0065] Figure 4 This is a schematic diagram of the structure of the differential pressure flow sensor in Example 3 of the present application;

[0066] Figure 5 This is a schematic structural diagram of the differential pressure flow sensor in Example 4 of the present application;

[0067] Figure 6 This is a schematic diagram of the structure of the differential pressure flow sensor in Example 5 of the present application;

[0068] Figure 7 This is a schematic diagram of the structure of the differential pressure flow sensor in Example 7 of the present application.

[0069] Explanation of the accompanying reference numerals: 1. First upstream surface; 2. Second upstream surface; 3. First downstream surface; 4. Second downstream surface; 5. Pressure sensor; 51. Corrugated diaphragm; 52. Silicone oil; 53. Chip; 6. Housing; 61. Silicone oil hole; 7. Mounting part; 8. Electric wire; 100. Micro liquid column; 200. Target plate. DETAILED DESCRIPTION

[0070] The following is combined with Figure 1-7 This application is described in further detail.

[0071] Example 1

[0072] The present application discloses a method for calculating fluid flow, comprising the following steps:

[0073] S1: A test body is provided, wherein the test body has a first flow-facing surface 1, a second flow-facing surface 2, a first back-flow surface 3, and a second back-flow surface 4, all of which are planes.

[0074] The test body can be a single unit or multiple separate units. When the test body is a single unit, it can be any block-shaped object with four or more planar sides. Preferably, the block has six or more sides, at least four of which are planar, and does not deform when subjected to fluid impact. The test body can be made of a rigid and corrosion-resistant material such as stainless steel or titanium alloy.

[0075] When the test body is configured as multiple separate parts, the test body can be four rigid test panels, with the first upstream surface 1, the second upstream surface 2, the first downstream surface 3, and the second downstream surface 4 being the side surfaces of each test panel. The test body can also include two test panels, with the first upstream surface 1 and the second upstream surface 2 being two different side surfaces of one test panel, and the first downstream surface 3 and the second downstream surface 4 being two different side surfaces of the other test panel.

[0076] The test body is secured within the test object, which is a pipe or other device for storing flowing fluid. In this embodiment, the test body comprises four independent test plates. As long as the four test plates are mounted at locations within the test object where the flow velocities are equal, or if the flow field within the test object is uniform, there are no specific requirements for the mounting positions of the four test plates.

[0077] Reference Figure 1The first oncoming surface 1, the second oncoming surface 2, the first backflow surface 3 and the second backflow surface 4 are located at positions with the same fluid flow rate, so that the forward flow direction X of the fluid is toward the first oncoming surface 1 and the second oncoming surface 2, and the fluid can continue to flow forward along the first oncoming surface 1 and the second oncoming surface 2, that is, the first oncoming surface 1 and the second oncoming surface 2 cannot form an area where the fluid forms a vortex or is blocked when they are placed; the forward flow direction X of the fluid is away from the first backflow surface 3 and the second backflow surface 4, and the fluid can continue to flow forward along the first backflow surface 3 and the second backflow surface 4, that is, the first backflow surface 3 and the second backflow surface 4 cannot form an area where the fluid forms a vortex or is blocked when they are placed.

[0078] S2: Obtain a first angle θ1 between the first oncoming surface 1 and the fluid flow direction, and a second angle θ2 between the second oncoming surface 2 and the fluid flow direction. The first angle and the second angle can be measured during the installation of the first oncoming surface 1 and the second oncoming surface 2. The first angle and the second angle are unequal and are both acute angles. Due to the unequal first angle and the second angle, the first oncoming surface 1 and the second oncoming surface 2 have different inclination angles, resulting in a different pressure on the first oncoming surface 1 and the second oncoming surface 2, forming a pressure differential.

[0079] Get the first pressure p on the first frontal surface 1 A , the second pressure p on the second frontal surface 2 B , the positive fluid pressure difference Δp between the first oncoming surface 1 and the second oncoming surface 2 is obtained 正 , positive fluid pressure difference Δp 正 is the first pressure p A and the second pressure p B difference.

[0080] S3: Based on Bernoulli's theorem and the principle of the forward impact of the microfluid column 100 on the target plate, the forward fluid velocity V is calculated according to the first angle, the second angle and the forward fluid pressure difference. 正 .

[0081] Specifically, first taking the first oncoming surface 1 as an example, the first angle θ1 between the first oncoming surface 1 and the fluid flow direction is an acute angle, and the fluid flow velocity V can be decomposed into a tangential component V parallel to the first oncoming surface 1 t and the normal component V perpendicular to the first flow surface 1 n .

[0082] (1) According to Bernoulli's theorem in fluid dynamics, the tangential component V can be calculated t The tangential pressure p1 generated by the fluid on the first flow surface 1.

[0083] Reference Figure 1The first angle between the first frontal surface 1 and the fluid flow velocity is θ1, the fluid flow velocity is V, and the tangential component of the fluid flow velocity is V t , V t =Vcosθ1, the normal component of the fluid velocity V n , V n =Vsinθ1.

[0084] According to Bernoulli's theorem in fluid dynamics, the tangential component of the fluid velocity V t The first frontal surface 1 is subjected to a pressure p1, satisfying the equation: p1+ρV t 2 / 2+ρgh=C, that is, p1=-ρV t 2 / 2-ρgh+C, where C is a constant.

[0085] (2) According to the principle of the positive impact of the microfluid column 100 on the target plate, the normal component V of the fluid velocity can be calculated n The normal pressure p2 generated by the fluid on the first frontal surface 1.

[0086] The following first describes in detail the principle of the forward impact of the micro-liquid column 100 on the target plate 200:

[0087] Reference Figure 2 Taking the micro-liquid column 100 with a cross-sectional area of S, a length of Δl and a velocity of v positively impacting the target plate as an example, the mass of the micro-liquid column 100 is m=ρSΔl, where ρ is the fluid density.

[0088] From the momentum theorem mv=FΔt, we can obtain ρSΔlv=FΔt, that is, ρ(Δl / Δt)v=F / S.

[0089] Since the object is a microfluid column 100, we can obtain Δl / Δt≈dl / dt=v, and F / S=p, where p is the positive impact pressure of the microfluid column 100 on the target plate, and we can further obtain p=ρv 2 .

[0090] Furthermore, since the pressure on the target plate caused by the immersion depth h in the fluid when the fluid is stationary is p0 = ρgh, therefore, p = ρv 2 +p0=ρv 2 +ρgh.

[0091] According to the principle of the positive impact of the microfluid column 100 on the target plate 200, the normal component V of the fluid velocity can be obtained. n The first frontal surface 1 is subjected to a pressure p2, satisfying the equation: p2 = ρV n 2 +ρgh.

[0092] Therefore, the pressure p on the first frontal surface 1 isA =p1+p2=(-ρV t 2 / 2-ρgh+C)+(ρV n 2 +ρgh)=ρ(V n 2 -V t 2 / 2)+C.

[0093] By tilting the first flow-facing surface 1, that is, the first angle and the second angle are both acute angles, the fluid flow velocity V can be decomposed into a tangential component V parallel to the first flow-facing surface 1. t and the normal component V perpendicular to the first flow surface 1 n , eliminating the static pressure ρgh caused by the weight of the liquid and improving the calculation accuracy.

[0094] Since V t =V 正 cosθ1,V n =V 正 sinθ1, we can get p A =ρ(V n 2 -V t 2 / 2)+C=ρV 2 正 (sin 2 θ1-cos 2 θ1 / 2)+C.

[0095] Similarly, using the Bernoulli theorem of fluid dynamics and the principle of the positive impact of the micro-fluid column 100 on the target plate 200, the second angle between the second oncoming surface 2 and the fluid flow rate is θ2, then the pressure p on the second oncoming surface 2 is B =ρV 2 正 (sin 2 θ2-cos 2 θ2 / 2)+C.

[0096] Then the pressure difference between the first oncoming surface 1 and the second oncoming surface 2, that is, the positive fluid pressure difference Δp 正 Satisfies the formula:

[0097]

[0098] By setting the inclination angles of the first oncoming surface 1 and the second oncoming surface 2 to be different, that is, the first angle and the second angle are not equal, the pressure on the first oncoming surface 1 is different from the pressure on the second oncoming surface 2, forming a pressure difference, and the forward fluid pressure difference Δp can be calculated. 正, eliminating the unknown constant C in the Bernoulli equation, further simplifying the calculation formula and improving the calculation accuracy.

[0099] Through the above Δp 正 The calculation formula shows that the positive fluid pressure difference Δp 正 With the fluid density ρ, the forward fluid velocity V 正 , the first angle θ1 and the second angle θ2 are related, so according to the fluid density ρ, the first angle θ1, the second angle θ2, the positive fluid pressure difference Δp 正 , the forward fluid velocity V can be calculated 正 .

[0100] S4: Obtain a third angle θ3 between the first back-flow surface 3 and the fluid flow direction, and a fourth angle θ4 between the second back-flow surface 4 and the fluid flow direction. The third angle and the fourth angle can be measured during the installation process of the first back-flow surface 3 and the second back-flow surface 4. The third angle and the fourth angle are not equal and are both acute angles. Because the third angle and the fourth angle are not equal, the inclination angles of the first back-flow surface 3 and the second back-flow surface 4 are different, and the pressure applied to the first back-flow surface 3 and the pressure applied to the second back-flow surface 4 are different, resulting in a pressure difference.

[0101] Get the third pressure p on the first backflow surface 3 C , the fourth pressure p on the second backflow surface 4 D , the reverse fluid pressure difference Δp between the first backflow surface 3 and the second backflow surface 4 is obtained 反 , reverse fluid pressure difference Δp 反 is the third pressure p C and the fourth pressure p D difference.

[0102] S5: Based on Bernoulli's theorem and the principle of the forward impact of the microfluid column 100 on the target plate 200, the reverse flow velocity V of the fluid is calculated according to the third angle, the fourth angle and the reverse fluid pressure difference. 反 , fluid reverse flow velocity V 反 The calculation method of the forward fluid velocity V in step S3 is the same as that in step S3. 正 The calculation method is the same.

[0103] The pressure difference between the first back-flow surface 3 and the second back-flow surface 4, that is, the reverse fluid pressure difference Δp 反 Satisfies the formula:

[0104]

[0105] By setting the first back-flow surface 3 and the second back-flow surface 4 with a pressure difference, the reverse fluid pressure difference Δp can be calculated. 反 . Reverse fluid pressure difference Δp 反 The fluid density ρ and the fluid reverse flow velocity V 反, the third angle θ3 and the fourth angle θ4 are related, according to the fluid density ρ, the third angle θ3, the fourth angle θ4, the reverse fluid pressure difference Δp 反 , the reverse flow velocity Vreverse of the fluid can be calculated.

[0106] S6: Forward flow Q within the cumulative time T (t1, t2) 正 and reverse flow Q 反 , the net flow within the time range T(t1, t2) can be calculated.

[0107] When detecting the flow rate, the first pressure p on the first frontal surface 1 is obtained in real time. A , the second pressure p on the second frontal surface 2 B , we can get the positive fluid pressure difference Δp in time t 正 The change of can be obtained by the forward pressure difference function p(t). In the time range T(t1, t2), the forward flow rate of the fluid is k1 is a coefficient related to the fluid density ρ, the first angle θ1 and the second angle θ2.

[0108] At the same time, the third pressure p on the first backflow surface 3 is obtained in real time C , the fourth pressure p on the second backflow surface 4 D , we get the reverse fluid pressure difference Δp in time t 反 The reverse pressure difference function q(t) can be obtained by changing the reverse pressure difference function. In the time range T(t1, t2), the reverse flow rate of the fluid is k2 is a coefficient related to the fluid density ρ, the third angle θ3, and the fourth angle θ4.

[0109] The net flow in the time range T(t1, t2) is

[0110] Example 2

[0111] Reference Figure 3 , the first angle θ1 and the second angle θ2 are complementary to each other, That is, the first oncoming surface 1 and the second oncoming surface 2 are perpendicular, and we can get The positive fluid pressure difference The third angle θ3 and the fourth angle θ4 are complementary to each other. That is, the first backflow surface 3 and the second backflow surface 4 are perpendicular to each other, so the reverse fluid pressure difference Further simplified forward fluid pressure difference Δp 正 and the reverse fluid pressure difference Δp 反 The calculation formula can improve the measurement accuracy.

[0112] Further, let (θ1≠π / 4), k is a coefficient related only to the fluid density ρ and the first angle θ1, then

[0113] Place the first oncoming surface 1 and the second oncoming surface 2 in the fluid so that but Forward fluid flow rate Fluid reverse flow rate

[0114] By selecting the angle values of θ1 and θ3, the calculation of cos2θ1 and cos2θ3 is eliminated, the calculation formula is simplified, and the forward fluid flow velocity V 正 Only with the fluid density ρ and the positive fluid pressure difference Δp 正 The reverse flow velocity V 反 Only with the fluid density ρ and the reverse fluid pressure difference Δp 反 It is related to the measurement of the fluid flow, excluding various complex factors and excluding approximate quantities (generally speaking, cos2θ1 and cos2θ3 can only take approximate values in the program). By adjusting the angles between the first front face 1, the second front face 2, the first back face 3 and the second back face 4 and the fluid flow direction during installation, the measurement accuracy can be improved as long as the accuracy of each angle is controlled during detection.

[0115] In the time range T(t1, t2), the fluid forward flow Fluid reverse flow The net flow in the time range T(t1, t2) is

[0116] Example 3

[0117] Based on the above-described fluid flow calculation method, this embodiment provides a differential pressure flow sensor, including a test body and a single-chip microcomputer. The test body has a first frontal surface 1, a second frontal surface 2, a first back-flow surface 3, and a second back-flow surface 4, all of which are planar. In this embodiment, the test body comprises four independent test plates, with the first frontal surface 1, the second frontal surface 2, the first back-flow surface 3, and the second back-flow surface 4 representing side surfaces of each test plate.

[0118] Reference Figure 4A pressure sensor 5 is installed on the first frontal surface 1 to detect the first pressure exerted on the first frontal surface 1; a pressure sensor 5 is installed on the second frontal surface 2 to detect the second pressure exerted on the second frontal surface 2; a pressure sensor 5 is installed on the first backflow surface 3 to detect the third pressure exerted on the first backflow surface 3; a pressure sensor 5 is installed on the second backflow surface 4 to detect the fourth pressure exerted on the second backflow surface 4; the single-chip microcomputer is electrically connected to each pressure sensor 5 to obtain the first angle between the first frontal surface 1 and the fluid flow direction, the second angle between the second frontal surface 2 and the fluid flow direction, the third angle between the first backflow surface 3 and the fluid flow direction, the fourth angle between the second backflow surface 4 and the fluid flow direction, the fluid density, the first pressure, the second pressure, the third pressure and the fourth pressure.

[0119] Among them, when using the first front face 1, the second front face 2, the first back face 3, and the second back face 4 for detection, the first angle and the second angle are not equal and are both acute angles, and the third angle and the fourth angle are not equal and are both acute angles. The single chip microcomputer calculates the forward fluid flow velocity V according to the first angle θ1, the second angle θ2, the first pressure p1, the second pressure p2 and the fluid density ρ. 正 According to the third angle θ3, the fourth angle θ4, the third pressure p3, the fourth pressure p4 and the fluid density ρ, the fluid reverse flow velocity V is calculated 反 ; According to the forward fluid flow rate V 正 and the fluid reverse flow velocity V 反 , calculate the forward flow Q within the cumulative time T(t1, t2) 正 and reverse flow Q 反 , and obtain the net flow within the time range T(t1, t2).

[0120] By adopting the above technical solution, the first oncoming surface 1 and the second oncoming surface 2 are placed obliquely at positions with the same fluid flow rate, so that the first angle and the second angle are not equal and are both acute angles, so that the pressure exerted on the first oncoming surface 1 is different from the pressure exerted on the second oncoming surface 2, forming a pressure difference.

[0121] It should be noted that if the flow velocity field within the test piece is uniform, with the fluid velocity being the same everywhere, there is no restriction on the specific positions of the first frontal surface 1, the second frontal surface 2, the first back-flow surface 3, and the second back-flow surface 4. If the flow velocity field within the test piece is non-uniform, the distances between the first frontal surface 1, the second frontal surface 2, the first back-flow surface 3, and the second back-flow surface 4 should be minimized.

[0122] The fluid flow rate can be decomposed into a tangential component parallel to the first oncoming surface 1 and a normal component perpendicular to the first oncoming surface 1. The tangential pressure exerted by the tangential component of the fluid on the first oncoming surface 1 can be calculated using the Bernoulli theorem in fluid dynamics. The normal pressure exerted by the normal component of the fluid on the first oncoming surface 1 can be calculated using the principle of the forward impact of the micro-liquid column 100 on the target plate 200. The pressure exerted on the first oncoming surface 1 is the sum of the tangential pressure and the normal pressure, which can eliminate the static pressure ρgh caused by the weight of the liquid and improve the calculation accuracy.

[0123] Similarly, the pressure on the second oncoming surface 2 can be calculated using the same method as above. Therefore, the pressure difference between the first oncoming surface 1 and the second oncoming surface 2 is the difference between the two pressures. This can eliminate the unknown constant C in the Bernoulli equation, further simplifying the calculation formula and improving the calculation accuracy.

[0124] The forward fluid pressure difference is related to the fluid density, the forward fluid flow rate, the first angle and the second angle. Therefore, the forward fluid flow rate can be calculated based on the fluid density, the first angle, the second angle and the forward fluid pressure difference; similarly, the reverse fluid pressure difference is related to the fluid density, the fluid reverse flow rate, the third angle and the fourth angle. Therefore, the fluid reverse flow rate can be calculated based on the fluid density, the third angle, the fourth angle and the reverse fluid pressure difference; according to the accumulation of the forward fluid flow rate and the fluid reverse flow rate in unit time, the net flow rate in unit time can be obtained.

[0125] Example 4

[0126] Reference Figure 5 The difference between Example 4 and Example 3 is that the test body includes two test plates, the first front surface 1 and the second front surface 2 are two different side surfaces on one of the test plates, and the first rear surface 3 and the second rear surface 4 are two different side surfaces on the other test plate.

[0127] The first oncoming surface 1 and the second oncoming surface 2 are perpendicular to each other, and the first angle and the second angle are complementary to each other, which can further simplify the calculation formula of the positive fluid pressure difference and improve the measurement accuracy. The angles between the first oncoming surface 1 and the second oncoming surface 2 and the fluid flow direction are θ1 and θ2 respectively.

[0128] The first backflow surface 3 and the second backflow surface 4 are perpendicular to each other, and the third angle and the fourth angle are complementary to each other, which can further simplify the calculation formula of the reverse fluid pressure difference and improve the measurement accuracy. The angles between the first backflow surface 3 and the second backflow surface 4 and the fluid flow rate are θ2 and θ4 respectively. θ1=θ2.

[0129] Through the above settings, the calculation of cos2θ1 and cos2θ2 is eliminated, the calculation formula is simplified, and the angles θ1 and θ2 between the sensor and the fluid flow direction are adjusted during installation. As long as the angles θ1 and θ2 are accurately controlled during detection, the measurement accuracy can be improved.

[0130] Example 5

[0131] Reference Figure 6 The difference between Example 5 and Example 4 is that the test body is a whole, which is a sealed shell 6. The shell 6 has four contact surfaces connected end to end in the circumferential direction. The four contact surfaces are the first upstream surface 1, the second upstream surface 2, the first downstream surface 3 and the second downstream surface 4, and each two adjacent contact surfaces are perpendicular to each other.

[0132] The single-chip microcomputer is located outside the sealed shell 6, and the pressure sensor 5 is electrically connected to the single-chip microcomputer. In order to facilitate the connection between the pressure sensor 5 and the single-chip microcomputer, the shell 6 is hollow, and the shell 6 is penetrated by a through-hole for the power supply line 8 to pass through. The wire 8 passes through the through-hole from the shell 6 and is connected to the single-chip microcomputer. Through the above-mentioned setting, the overall integration can be improved, the overall miniaturization can be achieved, and the distance between the first front flow surface 1, the second front flow surface 2, the first back flow surface 3 and the second back flow surface 4 can be reduced, so that the forward fluid flow rate at the position of the first front flow surface 1 and the second front flow surface 2 is kept consistent, and the reverse fluid flow rate at the position of the first back flow surface 3 and the second back flow surface 4 is kept consistent, thereby improving the measurement accuracy.

[0133] Housing 6 is provided with a mounting portion 7 for connection to the inner wall of the test piece, facilitating installation of the sensor within the test piece, ensuring the stability of the sensor's real-time pressure detection within the fluid, and improving measurement accuracy. In this embodiment, pressure sensor 5 is a strain gauge pressure sensor. In other embodiments, pressure sensor 5 may also be a capacitive pressure sensor or a piezoelectric pressure sensor.

[0134] When installing the housing 6, the angles between the first frontal surface 1, the second frontal surface 2, the first back-flow surface 3, and the second back-flow surface 4 and the fluid flow rate can be measured to obtain the first, second, third, and fourth angles. The differential pressure flow sensor inherits the advantages of flow meters based on fluid dynamics principles, such as orifice plate flowmeters and target flowmeters, while also avoiding some of their disadvantages, such as corrosion and dirt resistance, no need for zero point setting, support for frequent switching, and fixed components that are not easily dislodged. At the same time, it achieves overall miniaturization and reduces pressure loss, making it suitable as a pre-installed flow sensor component in intelligent pipe networks.

[0135] Example 6

[0136] The difference between Example 6 and Example 5 is that the mounting portion 7 on the housing 6 is provided with a threaded hole. When the housing 6 is installed in the test piece, it is threadedly connected to the inner wall of the test piece. After the housing 6 is installed, the first angle θ1 between the first frontal surface 1 and the fluid flow velocity and the third angle θ3 between the first rear surface 3 and the fluid flow velocity are: As long as it can be installed at the specified position of the test piece, the calculation of cos2θ1 and cos2θ3 is eliminated, the calculation formula is simplified, and the measurement accuracy can be improved.

[0137] It is understandable that if the maximum range of the pressure sensor 5 is p max , obviously Δp 正 <p max , Δp 反 <p max , (θ1≠π / 4), lim θ→π / 4 k→+∞, then lim θ→π / 4 V→+∞. By adjusting the angle θ1 between the sensor and the fluid flow direction during installation, the sensor's measuring range can be almost infinitely amplified, with an arbitrarily large measuring range.

[0138] Specifically, when implementing or producing intelligent pipe networks, a Δp value that enables the sensor to achieve the best working state can be selected. 正 , recorded as, then according to the estimated value of the maximum flow rate V max To calculate θ1, θ1<arccos((2 / 3) / ρV 2 max ) / 2, as long as θ1 satisfies the above inequality, the flow rate of the fluid to be measured is within the measuring range.

[0139] Example 7

[0140] Reference Figure 7 The difference between Example 7 and Example 5 is that the pressure sensor 5 is a piezoresistive pressure sensor, including a corrugated diaphragm 51, silicone oil 52 and a chip 53; the first upstream surface 1, the second upstream surface 2, the first back surface 3 and the second back surface 4 are all provided with mounting grooves, and the chip 53 is installed in the mounting grooves. The chip 53 is connected to a piezoresistor and a Huygens circuit, and the chip 53 is electrically connected to the single-chip computer. The corrugated diaphragm 51 is installed on the first upstream surface 1, the second upstream surface 2, the first back surface 3 and the second back surface 4. Silicone oil 52 is filled between the corrugated diaphragm 51 and the chip 53, and a silicone oil hole 61 is provided on the shell 6 to facilitate the injection of silicone oil 52 between the corrugated diaphragm 51 and the chip 53.

[0141] The pressure exerted on the corrugated diaphragm 51 is transmitted through silicone oil 52 to the piezoresistor on chip 53, causing the piezoresistor's resistance to change. The Huygens circuit then converts this resistance into an electrical signal for output. Chip 53 performs A / D conversion on the continuous electrical signal, converting it into a discrete digital signal. This information then determines the pressure exerted on the first frontal surface 1, the second frontal surface 2, the first back surface 3, and the second back surface 4. The real-time pressure data is then transmitted to the microcontroller for calculation.

[0142] The differential pressure flow sensor also includes a DTU remote transmitter, a power module, and a display module. The power module is electrically connected to the microcontroller, the DTU remote transmitter, the display module, and the pressure sensor 5, providing power to the entire device. The display module can be a dashboard or LED display, displaying pressure and flow data. The DTU remote transmitter is used to communicate with the IoT platform protocol, sending pressure and flow data to the IoT platform for storage.

[0143] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for calculating fluid flow, characterized in that: The following steps are involved: A test body is provided, wherein the test body has a first flow-facing surface (1), a second flow-facing surface (2), a first flow-removing surface (3) and a second flow-removing surface (4), all of which are planes; The test body is fixed in the test piece, so that the first oncoming surface (1), the second oncoming surface (2), the first backflow surface (3) and the second backflow surface (4) are located at positions with the same fluid flow rate, so that the forward flow direction of the fluid is toward the first oncoming surface (1) and the second oncoming surface (2), and the fluid can continue to flow forward along the first oncoming surface (1) and the second oncoming surface (2); the fluid flow direction is opposite to the first backflow surface (3) and the second backflow surface (4), and the fluid can continue to flow forward along the first backflow surface (3) and the second backflow surface (4); Obtaining a first angle between the first oncoming surface (1) and the direction of fluid flow, and a second angle between the second oncoming surface (2) and the direction of fluid flow, wherein the first angle and the second angle are not equal and are both acute angles, obtaining a first pressure on the first oncoming surface (1) and a second pressure on the second oncoming surface (2), and obtaining a positive fluid pressure difference between the first oncoming surface (1) and the second oncoming surface (2); Based on Bernoulli's theorem and the principle of the forward impact of the microfluid column (100) on the target plate (200), the forward fluid flow velocity V is calculated according to the first angle, the second angle and the forward fluid pressure difference. 正 ; Obtaining a third angle between the first backflow surface (3) and the fluid flow direction, and a fourth angle between the second backflow surface (4) and the fluid flow direction, wherein the third angle and the fourth angle are not equal and are both acute angles, obtaining a third pressure on the first backflow surface (3) and a fourth pressure on the second backflow surface (4), and obtaining a reverse fluid pressure difference between the first backflow surface (3) and the second backflow surface (4); Based on Bernoulli's theorem and the principle of the forward impact of the microfluid column (100) on the target plate (200), the reverse flow velocity V of the fluid is calculated according to the third angle, the fourth angle and the reverse fluid pressure difference. 反 ; as well as, By accumulating the forward flow Q within the time T(t1, t2) 正 and reverse flow Q 反 , calculate the net flow within the time range T(t1, t2).

2. The fluid flow calculation method according to claim 1, characterized in that: The first oncoming surface (1) and the second oncoming surface (2) are perpendicular to each other, and the angles between them and the fluid flow direction are θ1 and θ2 respectively. Then the pressure difference between the first oncoming surface (1) and the second oncoming surface (2) is and / or, The first backflow surface (3) and the second backflow surface (4) are perpendicular to each other, and the angles between them and the fluid flow velocity are θ2 and θ3 respectively. The pressure difference between the first backflow surface (3) and the second backflow surface (4) is 3. The fluid flow calculation method according to claim 1, characterized in that: The first oncoming surface (1) and the second oncoming surface (2) are perpendicular to each other, and the angles between them and the fluid flow direction are θ1 and θ2 respectively. The first backflow surface (3) and the second backflow surface (4) are perpendicular to each other, and the angles between them and the fluid flow velocity are θ2 and θ3 respectively. θ1=θ2.

4. The fluid flow calculation method according to claim 3, characterized in that: Forward fluid flow rate Fluid forward flow Fluid reverse flow rate Fluid reverse flow The net flow in the time range T(t1, t2) is 5. The fluid flow calculation method according to claim 3, characterized in that: Get the maximum value V of the forward fluid velocity max , the positive fluid pressure difference between the first oncoming surface (1) and the second oncoming surface (2), then θ1=θ2<arccos((2 / 3)· / ρV max 2 ) / 2.

6. A differential pressure flow sensor, characterized in that: include: A test body, the test body having a first oncoming surface (1), a second oncoming surface (2), a first backflow surface (3) and a second backflow surface (4), all of which are planes; a pressure sensor (5) is mounted on the first oncoming surface (1) for detecting a first pressure exerted on the first oncoming surface (1); a pressure sensor (5) is mounted on the second oncoming surface (2) for detecting a second pressure exerted on the second oncoming surface (2); a pressure sensor (5) is mounted on the first backflow surface (3) for detecting a third pressure exerted on the first backflow surface (3); a pressure sensor (5) is mounted on the second backflow surface (4) for detecting a fourth pressure exerted on the second backflow surface (4); and, a single chip microcomputer, electrically connected to each of the pressure sensors (5), for obtaining a first angle between the first frontal surface (1) and the fluid flow direction, a second angle between the second frontal surface (2) and the fluid flow direction, a third angle between the first backflow surface (3) and the fluid flow direction, a fourth angle between the second backflow surface (4) and the fluid flow direction, a fluid density, the first pressure, the second pressure, the third pressure, and the fourth pressure; The first angle and the second angle are not equal and are both acute angles, the third angle and the fourth angle are not equal and are both acute angles, and the single chip microcomputer calculates the forward fluid flow velocity V according to the first angle, the second angle, the first pressure, the second pressure and the fluid density. 正 ; According to the third angle, the fourth angle, the third pressure, the fourth pressure and the fluid density, the fluid reverse flow velocity V is calculated 反 According to the forward fluid flow rate V 正 and the fluid reverse flow velocity V 反 , calculate the forward flow Q within the cumulative time T(t1, t2) 正 and reverse flow Q 反 , and obtain the net flow within the time range T(t1, t2).

7. The differential pressure flow sensor according to claim 6, characterized in that: The first oncoming surface (1) and the second oncoming surface (2) are perpendicular to each other; and / or, The first backflow surface (3) and the second backflow surface (4) are perpendicular to each other; and / or, The first oncoming surface (1) and the second oncoming surface (2) are perpendicular to each other, and the angles between them and the fluid flow direction are θ1 and θ2 respectively. The first backflow surface (3) and the second backflow surface (4) are perpendicular to each other, and the angles between them and the fluid flow velocity are θ2 and θ3 respectively. θ1=θ2.

8. The differential pressure flow sensor according to claim 6 or 7, characterized in that: The test body is a sealed shell (6), the shell (6) having four contact surfaces connected end to end in the circumferential direction, the four contact surfaces being the first upstream surface (1), the second upstream surface (2), the first downstream surface (3), and the second downstream surface (4), and the single chip microcomputer is located outside the shell (6).

9. The differential pressure flow sensor according to claim 8, characterized in that: Every two adjacent contact surfaces are perpendicular to each other; and / or, The housing (6) is provided with a mounting portion (7), and the mounting portion (7) is used to be connected to the inner wall of the test piece.

10. The differential pressure flow sensor according to claim 6 or 7, characterized in that: The single chip microcomputer is connected to a DTU remote transmission receiving device, and the DTU remote transmission receiving device is used to communicate with the Internet of Things platform protocol and send pressure data and flow data to the Internet of Things platform; and / or, The pressure sensor (5) comprises a corrugated diaphragm (51), silicone oil (52) and a chip (53); the first oncoming surface (1), the second oncoming surface (2), the first backflow surface (3) and the second backflow surface (4) are all provided with mounting grooves; the chip (53) is connected to a piezoresistor and a Huygens circuit; the chip (53) is mounted in the mounting groove; the chip (53) is connected to the single-chip microcomputer; the corrugated diaphragm (51) is mounted on the first oncoming surface (1), the second oncoming surface (2), the first backflow surface (3) and the second backflow surface (4); and the space between the corrugated diaphragm and the chip (53) is filled with the silicone oil (52).

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