Buffer device for pressure sensing of liquid pressure sensor

Abstract

The utility model discloses a buffer device for pressure sensing of a liquid pressure sensor, which belongs to the technical field of sensors and comprises a sensor pressure sensor for sensing liquid pressure, a connecting pipe which is mounted on the sensor pressure sensor in a threaded manner and is used for supporting, and a communicating hole which is formed in the connecting pipe and is used for circulating liquid. According to the utility model, liquid impacts on the conical sealing plate when entering the connecting pipe, the conical sealing plate is pushed away under the impact of the liquid, so that the liquid enters the pressure sensor through the communicating hole, and the conical sealing plate extrudes the two buffer springs and compresses the two buffer springs when being impacted, so that the flowing speed of the liquid can be slowed down; and the connecting sliding block can further compress the buffer spring by rotating the threaded adjusting ring, so that the buffer force of the conical sealing plate is further increased, the buffer effect is adjusted according to the flow velocity of the liquid, and the measurement accuracy of the sensor is improved.

Description

Technical Field

[0001] The utility model relates to the field of sensors, in particular to a buffer device used for pressure sensing of a liquid pressure sensor. Background Art

[0002] The working principle of liquid pressure sensor sensing pressure is mainly based on the direct action of pressure on the diaphragm of the sensor. When the liquid flows through the pressure sensor, the sensor senses the pressure change and causes the diaphragm to produce a micro-displacement proportional to the medium pressure. This micro-displacement further causes the resistance of the sensor to change. This change is then detected by the electronic circuit and converted to output a standard signal corresponding to this pressure.

[0003] Chinese patent announcement number CN203798484U discloses a buffer device for pressure sensing of a liquid pressure sensor, including an inner joint, a main body channel and an outer joint, wherein the inner joint is installed at one end of the main body channel, and the outer joint is installed at the other end of the main body channel, and a filter screen is provided between the outer joint and the main body channel; the inner joint, the main body channel and the outer joint are all hollow structures, and a through hole is provided with each axis as the center, and the inner joint, the main body channel and the outer joint are connected as a whole, and the inner joint is connected internally; a buffer cavity is provided at one end of the main body channel connected to the inner joint, and the diameter of the buffer cavity is greater than the diameter of the through hole inside the main body channel. This buffer device is installed in the joint of the liquid pressure sensor, and the liquid is filtered out of large particles of impurities through the filter screen, and is buffered into the pressure sensing chamber of the sensor through the buffer cavity, so that the pressure sensing chamber is free of pollution and damage caused by large particles of impurities, and at the same time, the flow rate of the liquid is buffered, and the sensitivity of the liquid sensing device is maintained for a long time.

[0004] However, the buffering function in the above-mentioned patent is mainly achieved by liquid passing through the buffer cavity. However, since the size of the buffer cavity cannot be adjusted, its buffering effect remains consistent and cannot be adjusted according to the liquid flow rate. When the liquid flow rate is faster than its buffering capacity, its buffering effect will be reduced, resulting in errors in sensor measurement. Utility Model Content

[0005] In view of the above-mentioned technical deficiencies, the purpose of the present utility model is to provide a buffer device for pressure sensing of a liquid pressure sensor, which can adjust the buffer force according to the liquid flow rate and improve the measurement accuracy of the sensor.

[0006] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0007] A buffer device for pressure sensing of a liquid pressure sensor, comprising:

[0008] Sensor pressure sensor, used to sense liquid pressure;

[0009] Connecting pipe, threadedly mounted on the pressure sensor of the sensor for support;

[0010] A communication hole is provided on the connecting pipe, the communication hole is connected to the pressure sensor of the sensor and is used for circulating liquid;

[0011] The buffer structure is arranged on the connecting pipe and is used to mitigate the impact of the liquid and adjust the buffer strength;

[0012] A filtering structure, arranged on the connecting pipe, for filtering impurities in the liquid;

[0013] The limiting structure is arranged on the connecting pipe to prevent the buffer structure from loosening after adjusting the buffering force.

[0014] Preferably, the buffer structure comprises:

[0015] A tapered hole is provided on the inner wall of the connecting pipe;

[0016] A guide rod, fixedly mounted on the inner wall of the connecting pipe, for guiding;

[0017] A sliding block, slidably mounted on the guide rod;

[0018] A connecting rod is fixedly mounted on one side of the sliding block, and the connecting rod contacts the inner wall of the tapered hole;

[0019] The conical sealing plate is fixedly mounted on the connecting rod, the conical sealing plate contacts the inner wall of the conical hole, and the conical sealing plate cooperates with the conical hole to alleviate the impact force of the liquid;

[0020] A buffer spring is slidably sleeved on the guide rod and is used for compression buffering;

[0021] A connecting slide block is slidably mounted on the guide rod;

[0022] A guide groove is provided on the inner wall of the connecting pipe, and a connecting slider is slidably installed in the guide groove to guide the moving direction of the guide groove;

[0023] A sealing assembly is arranged on the connecting slider to block the guide groove to prevent liquid from leaking out;

[0024] An adjusting component is arranged on the sealing component and is used to adjust the position of the sealing component and the strength of the connecting slider to squeeze the buffer spring;

[0025] One end of the buffer spring is fixedly mounted on the inner wall of the guide groove, and the other end of the buffer spring is fixedly mounted on the inner wall of the connecting pipe.

[0026] Preferably, the sealing assembly comprises:

[0027] The sealing sleeve is fixedly mounted on the connecting slide block, and the sealing sleeve is slidably sleeved on the connecting pipe to block the guide groove;

[0028] The two sealing rings are fixedly mounted on the inner wall of the sealing sleeve, and the two sealing rings are movably sleeved on the connecting pipe to improve the sealing performance of the sealing sleeve.

[0029] Preferably, the adjustment component comprises:

[0030] The threaded adjustment ring is rotatably mounted on the sealing sleeve;

[0031] A fixed threaded ring is fixedly sleeved on the connecting pipe, and a threaded adjustment ring is threadedly sleeved on the fixed threaded ring. The fixed threaded ring and the threaded adjustment ring cooperate to adjust the position of the sealing sleeve;

[0032] An annular groove is provided on the inner wall of the threaded adjustment ring;

[0033] The limiting ring is rotatably mounted on the inner wall of the annular groove and is fixedly mounted on one side of the sealing sleeve to limit the rotation track of the threaded adjusting ring.

[0034] Preferably, the filtering structure comprises:

[0035] A positioning groove is provided on the inner wall of the connecting pipe, and the sensor pressure sensor is threadedly installed in the positioning groove to prevent the sensor pressure sensor from offsetting from the connecting pipe;

[0036] A positioning ring, arranged on the inner wall of the positioning groove, for supporting the filtering structure;

[0037] A filter screen is arranged on the positioning ring, the filter screen corresponds to the communicating hole and is used for filtering;

[0038] The positioning assembly is arranged on the positioning ring and contacts one side of the pressure sensor of the sensor, and is used to prevent the filter screen from being skewed under the impact of the liquid.

[0039] Preferably, the positioning component comprises:

[0040] Two positioning holes are both opened on the positioning ring;

[0041] Two positioning pins are movably installed in the two positioning holes respectively, and the two positioning pins are fixedly installed on the inner wall of the positioning groove to prevent the positioning ring from deviating.

[0042] Preferably, the limiting structure includes:

[0043] An L-shaped support rod is arranged on the threaded adjustment ring and is used to support the limiting structure;

[0044] The adjusting screw hole is provided on the L-shaped support rod;

[0045] An adjusting screw, threadedly installed in the adjusting screw hole, is used to adjust its position by rotating the adjusting screw;

[0046] The rubber stopper is arranged at one end of the adjusting screw rod. The rubber stopper contacts the connecting pipe and is used for pressing against the outer surface of the connecting pipe to prevent the threaded adjusting ring from loosening.

[0047] The beneficial effects of the utility model are:

[0048] In the utility model, when liquid enters the connecting pipe, it will impact on the conical sealing plate, and the conical sealing plate will be pushed open under the impact of the liquid, so that the liquid enters the pressure sensor of the sensor through the connecting hole, and the conical sealing plate will squeeze and compress the two buffer springs when impacted, so as to slow down the flow speed of the liquid and play a buffering role, and by rotating the threaded adjustment ring, the connecting slider can further compress the buffer spring, so that the buffering force of the conical sealing plate is further increased, so that the buffering effect can be adjusted according to the flow rate of the liquid, thereby improving the measurement accuracy of the sensor.

[0049] In the utility model, when the liquid enters the connecting hole, it will pass through the mesh holes on the filter screen, and the impurities in the liquid will be blocked by the filter screen, thereby preventing the impurities from flowing into the sensor pressure sensor along with the liquid. When it is necessary to clean the impurities, it is only necessary to rotate the sensor pressure sensor to remove it, and then the filter screen can be taken out to clean the impurities or replace the filter screen to prevent blockage.

[0050] The utility model can adjust the position of the rubber stopper by rotating the adjusting screw rod, so that the rubber stopper is pressed against the outer surface of the connecting pipe, thereby limiting the position of the threaded adjusting ring, and preventing the threaded adjusting ring from loosening after adjusting the buffering force. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 A schematic structural diagram of a buffer device for pressure sensing of a liquid pressure sensor provided in an embodiment of the utility model;

[0053] Figure 2 A schematic diagram of a connecting pipe structure of a buffer device for pressure sensing of a liquid pressure sensor provided in an embodiment of the utility model;

[0054] Figure 3A schematic diagram of a positioning groove structure of a buffer device for pressure sensing of a liquid pressure sensor provided in an embodiment of the utility model;

[0055] Figure 4 A schematic cross-sectional view of a buffer device for pressure sensing of a liquid pressure sensor provided in an embodiment of the utility model;

[0056] Figure 5 A schematic diagram of the sealing sleeve structure of a buffer device for pressure sensing of a liquid pressure sensor provided in an embodiment of the utility model.

[0057] Description of reference numerals:

[0058] 1. Sensor pressure sensor; 2. Connecting pipe; 3. Connecting hole; 4. Conical hole; 401. Guide rod; 402. Sliding block; 403. Connecting rod; 404. Conical sealing plate; 405. Buffer spring; 406. Connecting slider; 407. Guide groove; 408. Sealing sleeve; 409. Sealing ring; 410. Threaded adjustment ring; 411. Fixed threaded ring; 412. Annular groove; 413. Limiting ring; 5. Positioning groove; 501. Positioning ring; 502. Filter; 503. Positioning hole; 504. Positioning pin; 6. L-shaped support rod; 601. Adjusting screw hole; 602. Adjusting screw; 603. Rubber block. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0060] Embodiment 1:

[0061] like Figures 1 to 5 As shown, the utility model provides a buffer device for pressure sensing of a liquid pressure sensor, comprising: a sensor pressure sensor 1 for sensing liquid pressure, a connecting pipe 2 threadedly mounted on the sensor pressure sensor 1 for support, a connecting hole 3 opened on the connecting pipe 2 for circulating liquid, and the connecting hole 3 is connected to the sensor pressure sensor 1.

[0062] In order to adjust the strength of liquid buffering according to the flow rate of the liquid and prevent measurement errors caused by excessive liquid flow rate, a buffer structure is arranged on the connecting pipe 2 to mitigate the impact of the liquid and adjust the buffering strength.

[0063] Among them, the buffer structure includes a tapered hole 4 opened on the inner wall of the connecting pipe 2, a guide rod 401 fixedly installed on the inner wall of the connecting pipe 2 for guiding, a sliding block 402 slidably installed on the guide rod 401, a connecting rod 403 fixedly installed on one side of the sliding block 402, the connecting rod 403 contacts the inner wall of the tapered hole 4, a tapered sealing plate 404 fixedly installed on the connecting rod 403 for alleviating the impact force of the liquid, the tapered sealing plate 404 contacts the inner wall of the tapered hole 4, a buffer spring 405 slidably sleeved on the guide rod 401 for compression buffering, a connecting slider 406 slidably installed on the guide rod 401, a guide groove 407 opened on the inner wall of the connecting pipe 2 for guiding the moving direction of the guide groove 407, and a connecting slider 406 slidingly installed A sealing component is installed in the guide groove 407 and arranged on the connecting slider 406 to block the guide groove 407 to prevent liquid from seeping out. An adjusting component is arranged on the sealing component to adjust the position of the sealing component and the strength of the connecting slider 406 to squeeze the buffer spring 405. One end of the buffer spring 405 is fixedly mounted on the inner wall of the guide groove 407, and the other end of the buffer spring 405 is fixedly mounted on the inner wall of the connecting pipe 2. When the conical sealing plate 404 is impacted, it will drive the two sliding blocks 402 to slide on the corresponding guide rod 401 through the two connecting rods 403. When the connecting rod 403 slides, it will squeeze the buffer spring 405 to compress the buffer spring 405, and the flow rate of the liquid passing through is reduced through the cooperation of the conical sealing plate 404 and the buffer spring 405.

[0064] Among them, the sealing component includes a sealing sleeve 408 fixedly installed on the connecting slider 406 for blocking the guide groove 407, the sealing sleeve 408 is slidably sleeved on the connecting pipe 2, and two sealing rings 409 are fixedly installed on the inner wall of the sealing sleeve 408. The two sealing rings 409 are movably sleeved on the connecting pipe 2 to improve the sealing performance of the sealing sleeve 408. By setting the sealing sleeve 408, the guide groove 407 can be blocked to prevent liquid from seeping out through the guide groove 407. By setting two sealing rings 409 on the inner wall of the sealing sleeve 408, the two sealing rings 409 surround the two sides of the guide groove 407, which can improve the sealing performance of the sealing sleeve 408 and further prevent liquid from seeping out.

[0065] Among them, the adjustment component includes a threaded adjustment ring 410 rotatably installed on the sealing sleeve 408, a fixed threaded ring 411 fixedly sleeved on the connecting pipe 2 for adjusting the position of the sealing sleeve 408, the threaded adjustment ring 410 is threadedly sleeved on the fixed threaded ring 411, an annular groove 412 is provided on the inner wall of the threaded adjustment ring 410, and a limiting ring 413 rotatably installed on the inner wall of the annular groove 412 for limiting the rotation trajectory of the threaded adjustment ring 410. Rotating the threaded adjustment ring 410 can make it rotate and move on the fixed threaded ring 411. During the rotation of the threaded adjustment ring 410, it will rotate on the limiting ring 413 through the annular groove 412, thereby limiting the rotation trajectory of the threaded adjustment ring 410.

[0066] Embodiment 2:

[0067] On the basis of Example 1, in order to prevent impurities in the liquid from entering the sensor pressure sensor 1 along with the liquid, a filtering structure is arranged on the connecting pipe 2 to filter the impurities in the liquid.

[0068] Among them, the filtering structure includes a positioning groove 5 opened on the inner wall of the connecting pipe 2 for preventing the sensor pressure sensor 1 from being offset from the connecting pipe 2. The sensor pressure sensor 1 is threadedly installed in the positioning groove 5, and a positioning ring 501 is arranged on the inner wall of the positioning groove 5 for supporting the filtering structure. A filter screen 502 for filtering is arranged on the positioning ring 501. The filter screen 502 corresponds to the connecting hole 3. A positioning component is arranged on the positioning ring 501 and contacts one side of the sensor pressure sensor 1 to prevent the filter screen 502 from being skewed under the impact of liquid. When the liquid passes through the filter screen 502, impurities can be filtered to prevent impurities in the liquid from entering the sensor pressure sensor 1.

[0069] Among them, the positioning component includes two positioning holes 503 both opened on the positioning ring 501, and two positioning pins 504 movably installed in the two positioning holes 503 for preventing the positioning ring 501 from being offset. The two positioning pins 504 are fixedly installed on the inner wall of the positioning groove 5. With the cooperation of the positioning pins 504 and the positioning holes 503, the filter net 502 can be prevented from being offset.

[0070] Embodiment three:

[0071] On the basis of Example 1, in order to prevent the sealing sleeve 408 from loosening after the buffering force is adjusted, a limiting structure is arranged on the connecting pipe 2 to improve the stability of the buffering structure.

[0072] Among them, the limiting structure includes an L-shaped support rod 6 arranged on the threaded adjustment ring 410 for supporting the limiting structure, an adjusting screw hole 601 opened on the L-shaped support rod 6, an adjusting screw 602 threadedly installed in the adjusting screw hole 601 for adjusting its position when the adjusting screw 602 is rotated, and a rubber stopper 603 arranged at one end of the adjusting screw 602 for pressing against the outer surface of the connecting pipe 2 to prevent the threaded adjustment ring 410 from loosening. The rubber stopper 603 is in contact with the connecting pipe 2. Rotating the adjusting screw 602 can drive the rubber stopper 603 to press against the outer surface of the connecting pipe 2 to prevent the threaded adjustment ring 410 from loosening, so that the conical sealing plate 404 can maintain the buffering effect.

[0073] Working principle: Connect the connecting pipe 2 to the liquid pipeline. When the liquid circulates, it can enter the connecting pipe 2 and impact the conical sealing plate 404. When the conical sealing plate 404 is impacted, it will drive the two sliding blocks 402 to slide on the corresponding guide rods 401 through the two connecting rods 403. When the connecting rods 403 slide, they will squeeze the buffer spring 405 to compress the buffer spring 405. At the same time, the conical sealing plate 404 that is impacted will open the conical hole 4, so that the liquid can enter the connecting hole 3 through the conical hole 4, and pass through the filter 502. Filtering is performed to prevent impurities in the liquid from entering the sensor pressure sensor 1, and finally entering the sensor pressure sensor 1 through the connecting hole 3. When it is necessary to clean the impurities on the filter screen 502, the sensor pressure sensor 1 can be rotated to screw it out of the connecting pipe 2, and the sensor pressure sensor 1 will be separated from the pressure on the positioning ring 501, and then the positioning ring 501 is pulled, so that the positioning ring 501 drives the positioning hole 503 to be disengaged from the positioning pin 504, and the filter screen 502 is taken out for cleaning or replacement, and the conical sealing plate 40 is used to remove the impurities on the filter screen 502. 4 cooperates with the buffer spring 405 to reduce the flow rate of the liquid when passing through, and by rotating the threaded adjustment ring 410, it can be rotated and moved on the fixed threaded ring 411. At the same time, the moving threaded adjustment ring 410 will drive the sealing sleeve 408 to move through the cooperation of the annular groove 412 and the limiting ring 413. When the sealing sleeve 408 moves, it will drive the two connecting sliders 406 to slide in the two guide grooves 407 respectively, thereby limiting the moving direction of the sealing sleeve 408, and the continuously sliding connecting slider 406 will squeeze the buffer spring 40 5, so that the compression force of the buffer spring 405 is increased, and the buffer force can be increased when the subsequent liquid impacts the conical sealing plate 404, so that it can be adjusted according to the liquid flow rate. After the adjustment is completed, the adjusting screw 602 can be rotated, and the adjusting screw 602 will rotate and move in the adjusting screw hole 601 on the L-shaped support rod 6, so that the moving adjusting screw hole 601 drives the rubber stop block 603 to press against the outer surface of the connecting pipe 2, preventing the threaded adjustment ring 410 from rotating and loosening, so that the conical sealing plate 404 can maintain the current buffer force.

[0074] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A buffer device for pressure sensing of a liquid pressure sensor, characterized in that: include: Sensor pressure sensor (1), used for sensing liquid pressure; A connecting pipe (2) is threadedly mounted on the sensor pressure sensor (1) for support; A communication hole (3) is provided on the connecting pipe (2), the communication hole (3) is connected to the sensor pressure sensor (1) and is used for circulating liquid; A buffer structure is arranged on the connecting pipe (2) and is used to mitigate the impact of the liquid and can adjust the buffer strength; A filtering structure, arranged on the connecting pipe (2) and used for filtering impurities in the liquid; The limiting structure is arranged on the connecting pipe (2) to prevent the buffer structure from loosening after adjusting the buffering force.

2. A buffer device for pressure sensing of a liquid pressure sensor as claimed in claim 1, characterized in that: The buffer structure comprises: A tapered hole (4) is formed on the inner wall of the connecting pipe (2); A guide rod (401) is fixedly mounted on the inner wall of the connecting pipe (2) and is used for guiding; A sliding block (402) is slidably mounted on the guide rod (401); A connecting rod (403) is fixedly mounted on one side of the sliding block (402), and the connecting rod (403) is in contact with the inner wall of the tapered hole (4); A conical sealing plate (404) is fixedly mounted on the connecting rod (403), the conical sealing plate (404) is in contact with the inner wall of the conical hole (4), and the conical sealing plate (404) cooperates with the conical hole (4) to alleviate the impact force of the liquid; A buffer spring (405) is slidably sleeved on the guide rod (401) and is used for compression buffering; A connecting slider (406) is slidably mounted on the guide rod (401); A guide groove (407) is provided on the inner wall of the connecting pipe (2), and a connecting slider (406) is slidably installed in the guide groove (407) to guide the moving direction of the guide groove (407); A sealing assembly is arranged on the connecting slider (406) to block the guide groove (407) to prevent liquid from leaking out; An adjusting component, arranged on the sealing component, for adjusting the position of the sealing component and the strength of the connecting slider (406) to squeeze the buffer spring (405); One end of the buffer spring (405) is fixedly mounted on the inner wall of the guide groove (407), and the other end of the buffer spring (405) is fixedly mounted on the inner wall of the connecting pipe (2).

3. A buffer device for pressure sensing of a liquid pressure sensor as claimed in claim 2, characterized in that: The sealing assembly comprises: A sealing sleeve (408) is fixedly mounted on the connecting slider (406), and the sealing sleeve (408) is slidably sleeved on the connecting pipe (2) to block the guide groove (407); The two sealing rings (409) are fixedly mounted on the inner wall of the sealing sleeve (408). The two sealing rings (409) are movably sleeved on the connecting pipe (2) to improve the sealing performance of the sealing sleeve (408).

4. A buffer device for pressure sensing of a liquid pressure sensor as claimed in claim 2, characterized in that: The adjustment component comprises: A threaded adjustment ring (410) is rotatably mounted on the sealing sleeve (408); A fixed threaded ring (411) is fixedly sleeved on the connecting pipe (2), and a threaded adjustment ring (410) is threadedly sleeved on the fixed threaded ring (411). The fixed threaded ring (411) and the threaded adjustment ring (410) cooperate to adjust the position of the sealing sleeve (408); An annular groove (412) is formed on the inner wall of the threaded adjustment ring (410); The limiting ring (413) is rotatably mounted on the inner wall of the annular groove (412). The limiting ring (413) is fixedly mounted on one side of the sealing sleeve (408) and is used to limit the rotation track of the threaded adjustment ring (410).

5. A buffer device for pressure sensing of a liquid pressure sensor as claimed in claim 1, characterized in that: The filtering structure comprises: A positioning groove (5) is formed on the inner wall of the connecting pipe (2), and the sensor pressure sensor (1) is threadedly installed in the positioning groove (5) to prevent the sensor pressure sensor (1) from being offset from the connecting pipe (2); A positioning ring (501) is arranged on the inner wall of the positioning groove (5) and is used to support the filtering structure; A filter screen (502) is arranged on the positioning ring (501), the filter screen (502) corresponds to the communication hole (3) and is used for filtering; The positioning assembly is arranged on the positioning ring (501) and contacts one side of the sensor pressure sensor (1), and is used to prevent the filter screen (502) from tilting under the impact of liquid.

6. A buffer device for pressure sensing of a liquid pressure sensor as claimed in claim 5, characterized in that: The positioning component comprises: Two positioning holes (503) are both formed on the positioning ring (501); Two positioning pins (504) are movably mounted in the two positioning holes (503) respectively, and the two positioning pins (504) are fixedly mounted on the inner wall of the positioning groove (5) to prevent the positioning ring (501) from deviating.

7. A buffer device for pressure sensing of a liquid pressure sensor as claimed in claim 1, characterized in that: The limiting structure comprises: An L-shaped support rod (6) arranged on the threaded adjustment ring (410) and used to support the limiting structure; An adjusting screw hole (601) is provided on the L-shaped support rod (6); An adjusting screw (602) is threadedly mounted in the adjusting screw hole (601) and is used to adjust the position of the adjusting screw (602) by rotating the adjusting screw (602); The rubber stopper (603) is arranged at one end of the adjusting screw rod (602). The rubber stopper (603) is in contact with the connecting pipe (2) and is used to press against the outer surface of the connecting pipe (2) to prevent the threaded adjusting ring (410) from loosening.

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