Fluid pressure detection device capable of reducing and adjusting resistance

Abstract

The invention relates to a fluid pressure detection device capable of adjusting resistance in a reducing manner. Comprising a detection box body, a strain type pressure sensor, a Venturi tube, a Venturi tube opening and closing mechanism, a piston mechanism and a filter screen opening and closing mechanism. When the filter screen is blocked, the piston can be driven to move through pressure change when the filter screen is blocked, then the Venturi tube is driven to be opened, the filter screen is driven to be opened by a certain angle, sediment on the filter screen is sucked through negative pressure generated by water flow entering the Venturi tube in a throat, the filter screen is automatically cleaned, and the pressure in the filter screen is recovered after blockage of the filter screen is relieved. The piston is reset to automatically drive the filter screen to reset and close the venturi tube. The device has the advantage of automatically cleaning the filter screen without manual cleaning.

Description

Technical Field

[0001] The invention relates to a fluid pressure detection device capable of adjusting resistance by changing diameter. Background Art

[0002] As one of the world's most sediment-laden rivers, the Yellow River's embankments face long-standing threats from sediment accumulation and erosion, significantly increasing the risk of embankment failure. To ensure embankment stability, real-time monitoring of internal pressure changes is essential. Strain gauge pressure sensors, due to their high sensitivity and reliability, are widely used for seepage pressure monitoring. By measuring the pressure differential between the inside and outside of the dam, these sensors can provide early warning of potential risks such as piping and leakage, becoming a key data source for flood control decisions.

[0003] Traditional strain gauge pressure sensors typically use a metal filter or fiber filter layer at the water inlet to prevent sediment from entering the sensor cavity. However, in the highly sediment-laden water environment of the Yellow River, the filter is prone to the following problems: Physical blockage: sediment particles (particle size 0.05-2mm) accumulate on the filter surface, resulting in a decrease in porosity and distortion of pressure transmission; Difficult maintenance: The sensors are installed deep inside the dam wall. Manual dredging requires stopping monitoring and dismantling the equipment, which is time-consuming and costly.

[0004] Existing solutions (such as increasing the filter mesh aperture or using multi-layer filtration) can delay clogging, but cannot avoid it. After clogging, manual cleaning is still required, and pressure detection accuracy is sacrificed. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a fluid pressure detection device with variable diameter and adjustable resistance, which can use the pressure change when the filter is blocked to drive the piston movement, thereby driving the Venturi tube to open and drive the filter to open a certain angle, and use the negative pressure generated by the water flow entering the Venturi tube at its throat to suck the mud and sand on the filter, automatically cleaning the filter. After the filter is unblocked, the pressure inside the filter is restored, and the piston resets, automatically driving the filter to reset and closing the Venturi tube.

[0006] The technical solution of the present invention is as follows: A fluid pressure detection device with variable diameter and adjustable resistance comprises: The detection box is used to be installed and fixed on the inner wall of the dam, and has an opening, and a rigid filter is provided at the opening; The strain gauge pressure sensor is installed on one inner wall of the detection box; The venturi tube comprises a main pipe arranged along the flow direction of the river water, the main pipe comprising an inlet section, a contraction section, a throat and a diffusion section connected in sequence, a suction pipe being vertically connected to the throat of the main pipe, and the inlet of the suction pipe being arranged corresponding to the outer surface of the rigid filter screen; The piston mechanism is vertically mounted on the outer wall of the detection box on the side facing the water flow direction, and includes a piston cylinder, a piston, a piston rod and a spring. The rodless cavity of the piston is connected to the interior of the detection box. The spring is sleeved on the piston rod and presses against the piston and the piston cylinder respectively to provide an elastic force for the piston toward the rodless cavity. The rear end of the piston rod passes through the piston cylinder, and the rear end of the piston rod is provided with a long through hole extending along its axial direction. The venturi tube opening and closing mechanism includes a lever and a hinged fulcrum. The front end of the lever is provided with an elastic sealing ball for sealing with the inlet section. The rear end of the lever is slidably assembled in the through-long hole. After the piston rod moves a certain distance, it can drive the lever to rotate around the hinged fulcrum to open and close the inlet section. The filter opening and closing mechanism includes a connecting rod, one end of which is hinged to the rear end of the lever, and the other end is hinged to the side of the rigid filter facing the water flow direction. The side of the rigid filter facing away from the water flow direction is hinged to the edge of the opening of the detection box. The side of the rigid filter facing the water flow direction is connected to the corresponding edge of the opening of the detection box through a flexible filter.

[0007] Based on the above solution, a further improvement is made as follows: the Venturi tube is tilted so that when the rigid filter is rotated about its hinge point to the extreme open position, the axis of the suction pipe is perpendicular to the outer surface of the rigid filter. This design allows for a better fit with the tilted rigid filter after opening, resulting in higher suction efficiency and substantially uniform suction across the rigid filter's outer surface, making suction more uniform.

[0008] Based on the above solution, a further improvement is made as follows: the connecting rod is an elastic connecting rod, and its length can be adjusted along the axial direction. Setting the connecting rod as an elastic connecting rod can avoid dead points and jamming.

[0009] Based on the above solution, a further improvement is made as follows: a bell mouth is provided at the inlet of the suction pipe to increase the suction coverage.

[0010] Based on the above solution, a further improvement is as follows: the inlet of the inlet section has a bell mouth, and the elastic sealing ball contacts and cooperates with the bell mouth to achieve a sealed closure of the inlet section. The inner conical surface of the bell mouth can be used to better cooperate with the spherical surface of the elastic sealing ball to achieve a better seal.

[0011] Based on the above solution, the following improvement is made: the strain gauge pressure sensor includes a pressure-sensitive diaphragm and a strain gauge resistor.

[0012] On the basis of the above solution, a further improvement is made as follows: an elastic sealing ring is embedded in the outer peripheral surface of the piston to slide and seal with the inner wall of the piston cylinder.

[0013] On the basis of the above solution, further improvements are made as follows: comprising a fixing frame fixed relative to the detection box, the venturi tube being fixed on the fixing frame, and the lever being hinged to the fixing frame via a hinge fulcrum.

[0014] Based on the above solution, a further improvement is as follows: the elastic sealing ball is a hollow ball, the front end of the lever has a circular plate, and the elastic sealing ball is connected to the circular plate. The hollow ball can reduce the weight of the elastic sealing ball, thereby reducing the required driving force.

[0015] Beneficial effects of the present invention: When the fluid pressure detection device with variable diameter and adjustable resistance of the present invention is in use, when mud and sand gradually accumulate on the outer surface of the filter and cause the rigid filter to be gradually blocked, the detection box is isolated from the external water pressure, and the pressure inside the detection box will decrease. At this time, the compressed spring pushes the piston to move toward the rodless chamber. After the piston rod moves a certain distance, the side wall of one side of the long hole contacts the rear end of the lever to drive the lever to rotate around its hinge fulcrum, driving the elastic sealing ball provided on its front end to move, thereby opening the opening of the inlet section of the Venturi tube, and the river water can enter the Venturi tube, and then flow through the contraction section, throat and diffusion section in sequence. Due to the Venturi effect, vacuum suction is generated at the throat and transmitted to the outer surface of the rigid filter through the suction pipe. At the same time, the rotation of the lever will also drive the connecting rod to rotate and move, thereby pushing the rigid filter to rotate around its hinge point. The side of the rigid filter facing the water flow opens, and the folded flexible filter gradually unfolds. The flexible filter plays a filtering role, preventing mud and sand from entering the detection area from the opening of the rigid filter. The box body, more importantly, because the flexible filter was in a folded state before and was not blocked, the detection box body that was originally in a closed state due to the blockage of the rigid filter screen is partially opened again. When the detection box body that has been out of the closed state is subjected to the suction force of the suction pipe, the mud and sand in the mesh of the rigid filter screen is more easily extracted. As the mud and sand in the mesh of the rigid filter screen is gradually sucked away, the connecting cross-section between the rigid filter screen and the outside world gradually increases, and the water pressure transmitted to the detection box body gradually increases. The water pressure will gradually overcome the elastic force of the spring and push the piston toward the rod chamber side to compress the spring. The piston rod drives the lever to rotate to gradually close the inlet of the inlet section of the elastic sealing ball, and at the same time drives the rigid filter screen to rotate in the opposite direction around its hinge point. The flexible filter screen is gradually folded and retracted until the blockage degree of the rigid filter screen reaches the set threshold again. The set threshold causes the water pressure in the detection water tank to drop again to a level that cannot overcome the elastic force of the spring, and the piston moves toward the rodless chamber again, thereby starting the next mud and sand suction cleaning, thereby forming a cycle process of automatically cleaning the mud and sand on the rigid filter screen. It can be seen that the technical solution of the present application can realize the automatic cleaning of the rigid filter at the opening of the detection box, avoid the long-term blockage of the filter and the malfunction of the strain gauge pressure sensor in the detection box, thereby ensuring the safety of the dam breach monitoring. Compared with the existing technology, the present application does not require manual cleaning of the filter. Instead, it uses the water flow and the variable diameter of the venturi tube to adjust the resistance to form a vacuum suction in the throat, and automatically opens the venturi tube to clean the filter due to the change in pressure when the filter is blocked. This clever cycle has the advantage of automatically completing the filter cleaning without manual cleaning. In addition, the design of the rigid filter opening on the side facing the water flow allows a part of the water flow to flush the rigid filter from the detection box after passing through the flexible filter, which also helps to flush out the mud and sand in the rigid filter.Furthermore, since the through-hole has a certain length, when the piston rod moves in the through-hole and does not contact the side walls on the left and right sides of the through-hole, there is no matching relationship between them, and the lever will not rotate. The purpose of such a setting is mainly to ensure that the Venturi tube only works when it needs to clear mud and sand, thereby minimizing the impact of the opening of the Venturi tube on the pressure in the detection box, which will interfere with the normal detection of the strain gauge pressure sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural schematic diagram of an embodiment of a fluid pressure detection device with variable diameter and adjustable resistance according to the present invention (non-working state); Figure 2 for Figure 1 A partial enlarged view of point A in the middle; Figure 3 for Figure 1 Structural diagram of the corresponding working state; Figure 4 for Figure 3 A partial enlarged view of point B in the middle; In the figure: 1-dam, 2-detection box, 21-opening, 22-rigid filter, 23-flexible filter, 24-strain type pressure sensor, 241-pressure sensitive diaphragm, 242-strain resistor, 25-side wall facing water flow, 251-connecting port, 26-side wall facing away from water flow, 3-Venturi tube, 31-bell mouth, 32-inlet section, 33-contraction section, 34-throat, 35-diffusion section, 36 -Suction pipe, 4-Piston mechanism, 41-Piston cylinder, 411-Rodless chamber, 412-Rod chamber, 42-Piston, 421-Elastic sealing ring, 43-Piston rod, 431-Through long hole, 44-Spring, 5-Venturi tube opening and closing mechanism, 51-Lever, 511-Circular plate, 52-Hinged fulcrum, 53-Elastic sealing ball, 6-Filter opening and closing mechanism, 61-Connecting rod, 7-Hinged shaft, 8-Sediment. DETAILED DESCRIPTION

[0017] In order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention and are not intended to limit the present invention. That is, the embodiments described herein are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein may be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely intended to represent selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0019] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0020] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0021] A specific embodiment of a fluid pressure detection device with variable diameter and adjustable resistance of the present invention: Taking the Yellow River detection as an example, Figure 1 As shown, the fluid pressure detection device with variable diameter and adjustable resistance mainly includes a detection box 2, a strain gauge pressure sensor 24, a Venturi tube 3, a Venturi tube opening and closing mechanism 5, a piston mechanism 4 and a filter opening and closing mechanism 6.

[0022] Specifically, if Figure 1-2 As shown, the detection box 2 is a stainless steel square box, the bottom plate of which is away from the opening 21 and is fixedly mounted on the inner wall of the dam 1 and is in the river. In the figure, the water flows from left to right. The detection box 2 has an opening 21, and a rigid filter screen 22 is provided at the opening 21. In the figure, the right end of the rigid filter screen 22 is hinged to the edge of the right side of the opening 21 of the detection box 2 through a hinge shaft 7, and the left end of the rigid filter screen 22 is hinged to the connecting rod through the hinge shaft 7, and is connected to the edge of the left side of the opening 21 of the detection box 2 through a flexible filter screen 23. The material of the rigid filter screen 22 can be stainless steel, and the material of the flexible filter screen 23 can be plastic or nylon rope, etc.

[0023] like Figure 1 、 2As shown, the strain type pressure sensor 24 is installed on one side inner wall of the detection box 2 (i.e., the side wall 26 facing away from the water flow), which includes a pressure-sensitive diaphragm 241 and a strain resistor 242. The strain resistor 242 is connected to other modules through wires to realize data conversion, analysis, calculation processing and wireless transmission functions. These are existing technologies and will not be repeated here.

[0024] like Figure 1 As shown, the Venturi tube 3 includes a main tube arranged along the river flow direction. The axis of the main tube is substantially or completely parallel to the flow direction. When completely parallel, the angle between the suction tube 36 and the main tube can be adjusted to maintain the angle shown in the figure. The main tube includes an inlet section 32, a contraction section 33, a throat 34, and a diffusion section 35, which are sequentially connected along the flow direction. A suction tube 36 is perpendicularly connected to the throat 34 of the main tube. The inlet of the suction tube 36 is arranged corresponding to the outer surface of the rigid filter 22. The inlet section 32 and the suction tube 36 are respectively provided with a bell mouth 31. The bell mouth 31 at the inlet of the suction tube 36 increases the suction coverage. The inlet of the inlet section 32 has a bell mouth 31. The elastic sealing ball 53 contacts the bell mouth 31 to achieve a sealed closure of the inlet section 32. The inner conical surface of the bell mouth 31 can be used to better match the spherical surface of the elastic sealing ball 53 to achieve a better seal. The venturi tube 3 is tilted so that when the rigid filter screen 22 is rotated about its hinge point and opened to the extreme position, the axis of the suction pipe 36 is perpendicular to the outer surface of the rigid filter screen 22. This design can better fit the tilted rigid filter screen 22 after opening, thereby improving the suction efficiency and ensuring that the suction force is basically uniform across the outer surface of the rigid filter screen 22, making the suction more uniform.

[0025] like Figure 2 As shown, the piston mechanism 4 is vertically mounted on the outer wall of the detection box 2 facing the water flow direction (i.e., the side wall 25 facing the water flow). The piston mechanism 4 includes a piston cylinder 41, a piston 42, a piston rod 43, and a spring 44. The rodless cavity 411 of the piston 42 communicates with the interior of the detection box 2 through a communication port 251. The spring 44 is sleeved on the piston rod 43 and presses against the piston 42 and the piston cylinder 41, respectively, to provide an elastic force for the piston 42 toward the rodless cavity 411. The rear end of the piston rod 43 extends through the piston cylinder 41. The rear end of the piston rod 43 is provided with an elongated hole 431 extending axially along the piston rod 43. The piston rod 43 can be a square rod. Alternatively, the piston 42 can be square while the piston rod 43 is round. An elastic sealing ring 421 is embedded on the outer circumference of the piston 42 to provide a sliding and sealing fit with the inner wall of the piston cylinder 41.

[0026] like Figure 1 、 2As shown, the Venturi tube opening and closing mechanism 5 includes a lever 51 and a hinge fulcrum 52. The front end of the lever 51 is provided with an elastic sealing ball 53 for sealingly engaging with the inlet section 32. The rear end of the lever 51 slides within the through-elongated hole 431. After the piston rod 43 moves a certain distance, it drives the lever 51 to rotate about the hinge fulcrum 52 to open and close the inlet section 32. Because the through-elongated hole 431 has a certain length, when the piston rod 43 moves within the through-elongated hole 431 and does not contact the left and right side walls of the through-elongated hole 431, there is no engagement between the piston rod 43 and the lever 51, and the lever 51 does not rotate. This arrangement is primarily intended to ensure that the Venturi tube 3 operates only when clearing sediment, thereby minimizing the impact of the opening of the Venturi tube 3 on the pressure within the detection box 2, which could interfere with the normal detection of the strain gauge pressure sensor 24. The elastic sealing ball 53 is a hollow ball. The front end of the lever 51 has a circular plate 511, to which the elastic sealing ball 53 is connected. The hollow ball can reduce the weight of the elastic sealing ball 53, thereby reducing the required driving force.

[0027] like Figure 2 As shown, the filter screen opening and closing mechanism 6 includes a connecting rod 61, one end of which is hinged to the rear end of the lever 51, and the other end is hinged to the side of the rigid filter screen 22 facing the water flow direction. The side of the rigid filter screen 22 facing away from the water flow direction is hinged to the edge of the opening 21 of the detection box 2. The side of the rigid filter screen 22 facing the water flow direction is connected to the corresponding edge of the opening 21 of the detection box 2 via the flexible filter screen 23. The connecting rod 61 is an elastic connecting rod 61, and its length can be adjusted along the axial direction. For example, the elastic structure formed by compressed gas is connected in series with the elastic connecting rod 61. The elastic connection 61 can avoid dead points and stagnation.

[0028] The fluid pressure detection device further includes a fixing frame not shown in the figure. The fixing frame is fixed relative to the detection box 2 , the venturi tube 3 is fixed on the fixing frame, and the lever 51 is hinged to the fixing frame via a hinge fulcrum 52 .

[0029] When the fluid pressure detection device with variable diameter and adjustable resistance of the present invention is used, Figure 1-2 As shown, when the silt 8 gradually accumulates on the outer surface of the rigid filter 22 and causes the rigid filter 22 to be gradually blocked, the detection box 2 is isolated from the external water pressure, and the pressure inside the detection box 2 will decrease. At this time, the compressed spring 44 pushes the piston 42 toward the rodless cavity 411. After the piston rod 43 moves a distance, as shown in FIG. Figure 3-4As shown, the side wall of the long hole 431 contacts the rear end of the lever 51 to drive the lever 51 to rotate around its hinge fulcrum 52, driving the elastic sealing ball 53 provided on the front end thereof to move, thereby opening the opening 21 of the inlet section 32 of the Venturi tube 3, allowing the river water to enter the Venturi tube 3, and then flow through the contraction section 33, throat 34 and diffusion section 35 in sequence. Due to the Venturi effect, vacuum suction is generated at the throat and transmitted to the outer surface of the rigid filter 22 through the suction pipe 36. At the same time, The rotation of the lever 51 also drives the connecting rod 61 to rotate and move, thereby pushing the rigid filter screen 22 to rotate around its hinge point, and the rigid filter screen 22 opens on the side facing the water flow, and gradually unfolds the folded flexible filter screen 23. The flexible filter screen 23 plays a filtering role, preventing the mud and sand 8 from entering the detection box 2 from the opening 21 of the rigid filter screen 22. More importantly, since the flexible filter screen 23 was in the folded state before, it was not blocked, so that the detection box 2, which was originally in a closed state due to the blockage of the rigid filter screen 22, can be opened again. When the detection box 2 is partially opened and out of the sealed state, it is easier to extract the mud and sand 8 in the mesh of the rigid filter 22 when it is sucked by the suction pipe 36. As the mud and sand 8 in the mesh of the rigid filter 22 is gradually sucked away, the connecting cross-section of the rigid filter 22 and the outside world gradually increases, and the water pressure transmitted to the detection box 2 gradually increases. The water pressure will gradually overcome the elastic force of the spring 44 and push the piston 42 toward the side of the rod chamber 412 to compress the spring 44, and the piston rod 43 drives the lever 51 to rotate. The elastic sealing ball 53 gradually closes the inlet of the inlet section 32, and at the same time drives the rigid filter screen 22 to rotate in the opposite direction around its hinge point. The flexible filter screen 23 is gradually folded and retracted until the blockage degree of the rigid filter screen 22 reaches the set threshold again. The set threshold reduces the water pressure in the detection water tank to a level that cannot overcome the elastic force of the spring 44. The piston 42 moves toward the rodless chamber 411 again, thereby starting the next suction and cleaning of the mud and sand 8, thereby forming a cycle process of automatically cleaning the mud and sand 8 on the rigid filter screen 22. It can be seen that the technical solution of the present application can realize the automatic cleaning of the rigid filter screen 22 at the opening 21 of the detection box body 2, avoiding the long-term blockage of the filter screen and causing the strain type pressure sensor 24 in the detection box body 2 to be unable to work normally, thereby ensuring the safety of the dam breach monitoring. Compared with the existing technology, the present application does not require manual cleaning of the filter screen, but uses the water flow and the variable diameter adjustment resistance of the venturi tube 3 to form a vacuum suction force in the throat 34, and automatically opens the venturi tube 3 to clean the filter screen due to the change in pressure when the filter screen is blocked. This clever cycle has the advantage of automatically completing the filter screen cleaning without manual cleaning. In addition, the design of the rigid filter screen 22 opening on the side facing the water flow allows a part of the water flow to flush the rigid filter screen 22 from the inside of the detection box body 2 to the outside after passing through the flexible filter screen 23, which also helps to flush out the mud and sand 8 in the rigid filter screen 22.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be based on the claims. Any equivalent structural changes made using the description and drawings of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A fluid pressure detection device with variable diameter and adjustable resistance, comprising: The detection box is used to be installed and fixed on the inner wall of the dam, and has an opening, and a rigid filter is provided at the opening; The strain gauge pressure sensor is installed on one inner wall of the detection box; It is characterized by further comprising: The venturi tube comprises a main pipe arranged along the flow direction of the river water, the main pipe comprising an inlet section, a contraction section, a throat and a diffusion section connected in sequence, a suction pipe being vertically connected to the throat of the main pipe, and the inlet of the suction pipe being arranged corresponding to the outer surface of the rigid filter screen; The piston mechanism is vertically mounted on the outer wall of the detection box on the side facing the water flow direction, and includes a piston cylinder, a piston, a piston rod and a spring. The rodless cavity of the piston is connected to the interior of the detection box. The spring is sleeved on the piston rod and presses against the piston and the piston cylinder respectively to provide an elastic force for the piston toward the rodless cavity. The rear end of the piston rod passes through the piston cylinder, and the rear end of the piston rod is provided with a long through hole extending along its axial direction. The venturi tube opening and closing mechanism includes a lever and a hinged fulcrum. The front end of the lever is provided with an elastic sealing ball for sealing with the inlet section. The rear end of the lever is slidably assembled in the through-long hole. After the piston rod moves a certain distance, it can drive the lever to rotate around the hinged fulcrum to open and close the inlet section. The filter opening and closing mechanism includes a connecting rod, one end of which is hinged to the rear end of the lever, and the other end is hinged to the side of the rigid filter facing the water flow direction. The side of the rigid filter facing away from the water flow direction is hinged to the edge of the opening of the detection box. The side of the rigid filter facing the water flow direction is connected to the corresponding edge of the opening of the detection box through a flexible filter.

2. A fluid pressure detection device with variable diameter and adjustable resistance according to claim 1, characterized in that: The venturi tube is tilted so that when the rigid filter screen rotates around its hinge point and opens to the extreme position, the axis of the suction pipe is perpendicular to the outer surface of the rigid filter screen.

3. The fluid pressure detection device with variable diameter and adjustable resistance according to claim 1, characterized in that: The connecting rod is an elastic connecting rod and its length can be adjusted along the axial direction.

4. The fluid pressure detection device with variable diameter and adjustable resistance according to claim 1, characterized in that: A bell mouth is provided at the inlet of the suction pipe.

5. The fluid pressure detection device with variable diameter and adjustable resistance according to claim 1, characterized in that: The inlet of the inlet section is provided with a bell mouth, and the elastic sealing ball contacts and cooperates with the bell mouth to achieve sealing closure of the inlet section.

6. The fluid pressure detection device with variable diameter and adjustable resistance according to claim 1, characterized in that: The strain gauge pressure sensor includes a pressure-sensitive diaphragm and a strain gauge resistor.

7. The fluid pressure detection device with variable diameter and adjustable resistance according to claim 1, characterized in that: The outer peripheral surface of the piston is inlaid with an elastic sealing ring to slide and seal with the inner wall of the piston cylinder.

8. The fluid pressure detection device with variable diameter and adjustable resistance according to claim 1, characterized in that: The invention comprises a fixing frame fixed relative to the detection box body, a venturi tube fixed on the fixing frame, and a lever hinged on the fixing frame through a hinge fulcrum.

9. The fluid pressure detection device with variable diameter and adjustable resistance according to claim 1, characterized in that: The elastic sealing ball is a hollow ball. The front end of the lever is provided with a circular plate, and the elastic sealing ball is connected to the circular plate.

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