A sewage treatment filtering device with replaceable ultrafiltration membrane filter element

Abstract

The application discloses a sewage treatment filtering device with replaceable ultrafiltration membrane filter elements, which comprises a rack and a plurality of replaceable ultrafiltration membrane filter element modules arranged in the rack. Each replaceable ultrafiltration membrane filter element module comprises an upper sliding block and a lower sliding block. The upper sliding block is arranged on the upper side of the rack in a sliding mode, and the lower sliding block is arranged on the lower side of the rack in a sliding mode. Two ultrafiltration membrane filter element interfaces are arranged on the upper sliding block and the lower sliding block respectively. A switchable three-way valve is arranged on the water inlet pipe and the water outlet pipe of each replaceable ultrafiltration membrane filter element module. The switchable three-way valve divides the water inlet pipe and the water outlet pipe into two paths and connects the two paths with the two ultrafiltration membrane filter element interfaces of the upper sliding block and the lower sliding block through hoses. The application can directly replace the filter elements on line without cutting off the sewage filtration, and the sewage filtration is not affected during the replacement process. The idle operation of the remaining equipment during the filter element replacement process is avoided, the energy utilization rate is improved, and energy saving and environmental protection are achieved.

Description

Technical Field

[0001] This invention relates to a wastewater treatment filtration device, and more particularly to a wastewater treatment filtration device with an online replaceable ultrafiltration membrane filter element, belonging to the field of wastewater treatment technology. Background Technology

[0002] With improved living standards, water pollution prevention and control have gained increasing attention, and wastewater treatment equipment is developing towards greater sophistication, energy efficiency, and environmental friendliness. Advanced energy-saving and environmentally friendly equipment requires wastewater treatment equipment to employ advanced technologies and meet energy-saving and environmental protection requirements. Ultrafiltration membrane cartridges are crucial components in wastewater treatment. Traditional ultrafiltration membrane wastewater treatment filtration devices require shutting off the wastewater inlet when replacing the cartridges. Then, the ultrafiltration membrane cartridges are replaced one by one on the equipment support. Because the filtration process is effectively interrupted during this process, other equipment on the wastewater treatment line remains operational, resulting in wasted energy. Furthermore, shutting off the filtration device and restarting it after cartridge replacement can easily generate water hammer in the wastewater pipeline, damaging valves, sensors, and cartridges, thus reducing the lifespan of the wastewater treatment equipment. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a wastewater treatment filtration device with online replacement of ultrafiltration membrane filter cartridges, thereby realizing online replacement of ultrafiltration membrane filter cartridges.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A wastewater treatment filtration device with online replaceable ultrafiltration membrane filter cartridges includes a frame and several online replaceable ultrafiltration membrane filter cartridge modules disposed within the frame. Each online replaceable ultrafiltration membrane filter cartridge module includes an upper slider and a lower slider. The upper slider is slidably disposed on the upper side of the frame, and the lower slider is slidably disposed on the lower side of the frame. Two ultrafiltration membrane filter cartridge interfaces are respectively provided on the upper slider and the lower slider. Each online replaceable ultrafiltration membrane filter cartridge module is equipped with a switchable three-way valve on its inlet pipe and outlet pipe. The switchable three-way valve divides the inlet pipe and outlet pipe into two paths, which are respectively connected to the two ultrafiltration membrane filter cartridge interfaces of the upper slider and the lower slider through flexible hoses.

[0006] Furthermore, an upper main pipe is provided on the upper side of the frame, and one end of several upper branch pipes is connected to the upper main pipe. The other ends of several upper branch pipes are respectively connected to the upper end of the online replaceable ultrafiltration membrane filter module through switchable three-way valves. The upper main pipe is equipped with an upper main pipe valve. A lower main pipe is provided on the lower side of the frame, and one end of several lower branch pipes is connected to the lower main pipe. The other ends of several lower branch pipes are respectively connected to the lower end of the online replaceable ultrafiltration membrane filter module through switchable three-way valves. The lower main pipe is equipped with a lower main pipe valve.

[0007] Furthermore, the upper side of the frame is provided with several upper slide rails, which are arranged in the front-to-back direction. The upper slide block of the online replaceable ultrafiltration membrane filter element module is slidably arranged on the upper slide rail. The lower side of the frame is provided with several lower slide rails, which are arranged in the front-to-back direction. The lower slide block of the online replaceable ultrafiltration membrane filter element module is slidably arranged on the lower slide rail. A positioning bolt is provided between the upper slide block and the upper slide rail, and a positioning bolt is provided between the lower slide block and the lower slide rail.

[0008] Furthermore, the switchable three-way valve includes a valve body, a semi-cylindrical valve core, a valve stem, a partition, and a valve drive mechanism. The valve body has a main interface at its upper end. A cylindrical cavity matching the outer diameter of the semi-cylindrical valve core is provided inside the valve body. The upper end of the cylindrical cavity is connected to the main interface. The semi-cylindrical valve core is rotatably disposed in the cylindrical cavity inside the valve body. The lower end of the semi-cylindrical valve core is fixedly connected to the upper end of the valve stem. The lower end of the valve stem protrudes from the bottom surface of the valve body and is connected to the valve drive mechanism, which drives its rotation. A water distribution cavity is provided at the lower end of the cylindrical cavity. A partition is fixed in the water distribution cavity to divide the water distribution cavity into a first sub-cavity and a second sub-cavity. A first branch interface and a second branch interface are provided on both sides of the lower end of the valve body. The first branch interface is connected to the first sub-cavity, and the second branch interface is connected to the second sub-cavity.

[0009] Furthermore, the upper end of the main interface is a cylindrical hole structure, and the lower end of the main interface is a frustum-shaped structure with a diameter that gradually increases from top to bottom, and the diameter of the lower end of the frustum-shaped structure is smaller than the diameter of the cylindrical cavity.

[0010] Furthermore, the upper end of the water-dividing cavity is a frustum-shaped structure with a diameter that gradually decreases from top to bottom, and the diameter of the upper end of the frustum-shaped structure is smaller than the diameter of the cylindrical cavity. The lower end of the water-dividing cavity is a cylindrical hole structure.

[0011] Furthermore, the partition is arranged in the water distribution cavity along the front-to-back direction. The front and rear edges of the partition match the shape of the inner wall of the water distribution cavity, and the front and rear edges of the partition are fixed on the inner wall of the water distribution cavity to divide the water distribution cavity into a first sub-cavity and a second sub-cavity. A cylindrical sleeve is arranged in the middle of the partition. The inner diameter of the cylindrical sleeve matches the outer diameter of the valve stem, and the valve stem is rotatably arranged in the cylindrical sleeve.

[0012] Furthermore, a small semi-cylindrical structure is provided at the lower center of the rectangular surface of the semi-cylindrical valve core. The rectangular surface of the small semi-cylindrical structure coincides with and is fixed to the rectangular surface of the semi-cylindrical valve core. The upper end of the valve stem is fixed at the lower center of the small semi-cylindrical structure and the semi-cylindrical valve core, and the diameter of the valve stem is smaller than the diameter of the small semi-cylindrical structure.

[0013] Furthermore, the valve drive mechanism includes a gear and a rack, the gear being fixed to the lower end of the valve stem and meshing with the rack, and the rack being fixed to the upper or lower slider.

[0014] Furthermore, the upper or lower slider slides back and forth along the frame, and the stroke of the upper slider corresponds to the semi-cylindrical valve core rotating 180° around the valve stem. The extreme positions of the upper or lower slider's back and forth sliding respectively correspond to the semi-cylindrical valve core completely blocking the first and second sub-cavities respectively.

[0015] Compared with the prior art, the present invention has the following advantages and effects:

[0016] 1. The present invention provides a wastewater treatment filtration device with online replacement of ultrafiltration membrane filter cartridges, which can directly replace the filter cartridges online without interrupting wastewater filtration, and the replacement process does not affect wastewater filtration. This avoids the idle operation of other equipment during the filter cartridge replacement process, improves energy utilization, and achieves energy saving and environmental protection.

[0017] 2. This invention, through the linkage design of the physical structure of the filter element replacement and the switchable three-way valve, enables the three-way valve to be controlled synchronously during filter element replacement to control the flow rate between the original and new filter elements. During the replacement process, the total sewage flow rate remains unchanged, and there will be no water hammer effect due to flow fluctuations. Moreover, the flow rate of the original filter element gradually decreases, while the flow rate of the new filter element gradually increases, achieving stable flow rate throughout the filter element replacement process. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a wastewater treatment filtration device with an online replaceable ultrafiltration membrane filter element according to the present invention.

[0019] Figure 2 This is a side view of the online replaceable ultrafiltration membrane filter module of the present invention.

[0020] Figure 3 This is a cross-sectional view of the switchable three-way valve of the present invention.

[0021] Figure 4 This is a cross-sectional view along line AA of the switchable three-way valve of the present invention.

[0022] Figure 5 This is a cross-sectional view of the switchable three-way valve of the present invention along the BB direction. Detailed Implementation

[0023] To illustrate in detail the technical solutions adopted by the present invention to achieve the intended technical objectives, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Furthermore, the technical means or technical features in the embodiments of the present invention can be replaced without creative effort. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0024] like Figure 1 As shown, a wastewater treatment filtration device with online replaceable ultrafiltration membrane filter cartridges according to the present invention includes a frame 1 and a plurality of online replaceable ultrafiltration membrane filter cartridge modules 2 disposed within the frame. Figure 2 As shown, each online replaceable ultrafiltration membrane filter module 2 includes an upper slider 3 and a lower slider 4. The upper slider 3 is slidably mounted on the upper side of the frame 1, and the lower slider 4 is slidably mounted on the lower side of the frame 1. The upper slider 3 and the lower slider 4 are respectively provided with two ultrafiltration membrane filter interfaces 5. Each online replaceable ultrafiltration membrane filter module 2 is provided with a switchable three-way valve 6 on its inlet and outlet water pipes. The switchable three-way valve 6 divides the inlet and outlet water pipes into two paths and connects them to the two ultrafiltration membrane filter interfaces 5 of the upper slider 3 and the lower slider 4 respectively through hoses 7. During operation, assuming the ultrafiltration membrane cartridge on the left needs to be replaced, install the new ultrafiltration membrane cartridge on the ultrafiltration membrane cartridge interface 5 on the right. At this time, the switchable three-way valve 6 is connected to the cartridge on the left. Then push the cartridge on the right to the left. During the pushing process, the switchable three-way valve 6 is switched simultaneously. When the cartridge on the right is pushed to the left, the switchable three-way valve 6 is connected to the cartridge on the right. At this time, the cartridge replacement is completed. The cartridge on the left can be removed and replaced with a new cartridge for backup.

[0025] like Figure 1 As shown, an upper main pipe 8 is provided on the upper side of the frame 1. One end of several upper branch pipes 9 is connected to the upper main pipe 8, and the other end of several upper branch pipes 9 is connected to the upper end of the online replaceable ultrafiltration membrane filter module 2 through a switchable three-way valve 6. The upper main pipe 8 is provided with an upper main pipe valve 10. A lower main pipe 11 is provided on the lower side of the frame 1. One end of several lower branch pipes 12 is connected to the lower main pipe 11, and the other end of several lower branch pipes 12 is connected to the lower end of the online replaceable ultrafiltration membrane filter module 2 through a switchable three-way valve 6. The lower main pipe 11 is provided with a lower main pipe valve 13.

[0026] The frame 1 has several upper slide rails arranged along the front-to-back direction. The upper slider 3 of the online replaceable ultrafiltration membrane filter module 2 is slidably mounted on the upper slide rails. The frame 1 also has several lower slide rails arranged along the front-to-back direction. The lower slider 4 of the online replaceable ultrafiltration membrane filter module 2 is slidably mounted on the lower slide rails. Positioning bolts are installed between the upper slider 3 and the upper slide rails, and similarly, between the lower slider 4 and the lower slide rails. The upper slider 3 and lower slider 4 slide back and forth on the upper and lower slide rails respectively to switch filter cartridges. To ensure the stability of the slider position after it slides into place, the positioning bolts lock the slider position. When sliding is needed, the positioning bolts are loosened, allowing the upper and lower sliders to slide easily. Once the slider has slid into place, the bolts are tightened to lock and fix the slider position.

[0027] like Figure 3 , 4 As shown in Figure 5, the switchable three-way valve 6 includes a valve body 14, a semi-cylindrical valve core 15, a valve stem 16, a partition 17, and a valve drive mechanism. A main interface 18 is opened at the upper end of the valve body 14. A cylindrical cavity 19 matching the outer diameter of the semi-cylindrical valve core 15 is provided inside the valve body 14. The upper end of the cylindrical cavity 19 communicates with the main interface 18. The semi-cylindrical valve core 15 is rotatably disposed within the cylindrical cavity 19 inside the valve body 14. The lower end of the semi-cylindrical valve core 15 is fixed to the upper end of the valve stem 16. The valve stem 16 is connected to the valve drive mechanism by extending its lower end through the bottom surface of the valve body 14. The valve drive mechanism drives the valve stem 16 to rotate. A water distribution chamber 20 is provided at the lower end of the cylindrical cavity 19. A partition 17 is fixed inside the water distribution chamber 20, dividing the water distribution chamber 20 into a first sub-chamber 21 and a second sub-chamber 22. A first sub-port 23 and a second sub-port 24 are opened on both sides of the lower end of the valve body 14. The first sub-port 23 is connected to the first sub-chamber 21, and the second sub-port 24 is connected to the second sub-chamber 22.

[0028] The upper end of the main interface 18 is a cylindrical hole structure, and the lower end of the main interface 18 is a frustum-shaped structure with a diameter that gradually increases from top to bottom, and the diameter of the lower end of the frustum-shaped structure is smaller than the diameter of the cylindrical cavity 19.

[0029] The upper end of the water-dividing cavity 20 is a frustum-shaped structure with a diameter that gradually decreases from top to bottom, and the diameter of the upper end of the frustum-shaped structure is smaller than the diameter of the cylindrical cavity 19. The lower end of the water-dividing cavity 20 is a cylindrical hole structure.

[0030] The main interface 18 and the water distribution cavity 20 achieve a transitional change in diameter through a frustum structure, and limit the vertical degree of freedom of the semi-cylindrical valve core 15 by the diameter difference with the cylindrical cavity 19.

[0031] The partition 17 is arranged in the water distribution cavity 20 along the front-to-back direction. The front and rear edges of the partition 17 match the shape of the inner wall of the water distribution cavity 20 and the front and rear edges of the partition 17 are fixed on the inner wall of the water distribution cavity 20, dividing the water distribution cavity 20 into the first sub-cavity 21 and the second sub-cavity 22. A cylindrical sleeve is provided in the middle of the partition 17. The inner diameter of the cylindrical sleeve matches the outer diameter of the valve stem 16. The valve stem 16 is rotatably arranged in the cylindrical sleeve.

[0032] A small semi-cylindrical structure 25 is provided at the lower center of the rectangular surface of the semi-cylindrical valve core 15. The rectangular surface of the small semi-cylindrical structure 25 coincides with and is fixed to the rectangular surface of the semi-cylindrical valve core 15. The upper end of the valve stem 16 is fixed at the lower center of the small semi-cylindrical structure 25 and the semi-cylindrical valve core 15, and the diameter of the valve stem 16 is smaller than the diameter of the small semi-cylindrical structure 25. The small semi-cylindrical structure 25 and the semi-cylindrical valve core 15 form a base structure that can accommodate the valve stem 16, ensuring a stable connection between the valve stem 16 and the semi-cylindrical valve core 15.

[0033] like Figure 2 and Figure 3 As shown, the valve drive mechanism includes a gear 26 and a rack 27. The gear 26 is fixed to the lower end of the valve stem 16 and meshes with the rack 27, which is fixed to the upper slider 3 or the lower slider 4. When the upper slider 3 and the lower slider 4 slide back and forth, the rack 27 slides synchronously with them, driving the gear 26 to rotate. This, in turn, causes the semi-cylindrical valve core 15 to rotate within the valve body 14 via the valve stem 16. This changes the area of ​​the semi-cylindrical valve core that blocks the first chamber 21 and the second chamber 22, respectively, thus achieving a coordinated change in the flow rate between the original and new filter elements when replacing the filter element, while maintaining a constant total flow rate and effectively preventing water hammer.

[0034] The upper slider 3 or the lower slider 4 slides back and forth along the frame 1. The stroke of the upper slider 3 sliding back and forth corresponds to the semi-cylindrical valve core 15 rotating 180° around the valve stem 16. The extreme positions of the upper slider 3 or the lower slider 4 sliding back and forth correspond to the semi-cylindrical valve core 15 completely covering the first sub-cavity 21 and the second sub-cavity 22 respectively.

[0035] When the wastewater treatment filtration device of the present invention, which allows for online replacement of ultrafiltration membrane filter cartridges, is working, taking the normal operation of the left filter cartridge as an example, the semi-cylindrical valve core 15 completely blocks the second compartment 22, and the wastewater flow completely flows from the first compartment 21 to the left filter cartridge. When the left filter cartridge reaches its service life and needs to be replaced, the new filter cartridge is installed on the ultrafiltration membrane filter cartridge interface 5 on the right side of the upper slider 3 and the lower slider 4. Then, the new filter cartridge is pushed to the left. During the pushing process, the rack 27 on the slider drives the gear 26 to rotate, thereby driving the semi-cylindrical valve core 15 to rotate within the valve body 14 through the valve stem 16. As the filter element 15 gradually rotates, the flow area of ​​the first chamber 21 gradually decreases, while the flow area of ​​the second chamber 22 gradually increases. The total flow area of ​​the two chambers remains equal, which causes the flow rate of the left filter element to gradually decrease, while the flow rate of the right filter element gradually increases by the same amount. The total flow rate of both filter elements remains constant, effectively preventing water hammer caused by sudden changes in flow rate during filter element replacement. When the new filter element is fully pushed to the left, the semi-cylindrical valve core 15 rotates 180° to completely block the first chamber 21 and fully open the second chamber 22, completing the filter element replacement.

[0036] This invention discloses a wastewater treatment filtration device with online replaceable ultrafiltration membrane cartridges. It enables direct online replacement of the cartridges without interrupting wastewater filtration, and the replacement process does not affect wastewater filtration. This avoids idle operation of other equipment during cartridge replacement, improving energy utilization and achieving energy conservation and environmental protection. Through the linkage design of the physical structure for cartridge replacement and a switchable three-way valve, this invention allows for synchronous control of the three-way valve during cartridge replacement to control the flow rate between the old and new cartridges. The total wastewater flow rate remains constant during replacement, preventing water hammer effects due to flow fluctuations. Furthermore, the flow rate of the old cartridge gradually decreases while the flow rate of the new cartridge gradually increases, achieving stable flow throughout the entire cartridge replacement process.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A wastewater treatment filtration device with online replaceable ultrafiltration membrane filter element, characterized in that: The system includes a frame and several online replaceable ultrafiltration membrane filter modules housed within the frame. Each online replaceable ultrafiltration membrane filter module includes an upper slider and a lower slider. The upper slider is slidably mounted on the upper side of the frame, and the lower slider is slidably mounted on the lower side of the frame. Each upper and lower slider has two ultrafiltration membrane filter interfaces. Each online replaceable ultrafiltration membrane filter module has a switchable three-way valve on its inlet and outlet pipes. The switchable three-way valve splits the inlet and outlet pipes into two paths, each connected to one of the two ultrafiltration membrane filter interfaces on the upper and lower sliders via flexible hoses. The switchable three-way valve includes a valve body, a semi-cylindrical valve core, a valve stem, a partition, and a valve drive mechanism. The valve body has a main interface at its upper end, and a cylindrical cavity matching the outer diameter of the semi-cylindrical valve core is located within the valve body. The upper end of the cylindrical cavity communicates with the main interface. The semi-cylindrical valve core is rotatably mounted within the cylindrical cavity of the valve body. Inside the cavity, the lower end of the semi-cylindrical valve core is fixedly connected to the upper end of the valve stem. The lower end of the valve stem protrudes from the bottom surface of the valve body and is connected to the valve drive mechanism, which drives its rotation. A water distribution cavity is provided at the lower end of the cylindrical cavity. A partition plate is fixed in the water distribution cavity, dividing the water distribution cavity into a first sub-cavity and a second sub-cavity. A first sub-port and a second sub-port are opened on both sides of the lower end of the valve body. The first sub-port communicates with the first sub-cavity, and the second sub-port is connected to the second sub-cavity. The valve drive mechanism includes a gear and a rack. The gear is fixed at the lower end of the valve stem and meshes with the rack. The rack is fixed on the upper slider or the lower slider. The upper slider or the lower slider slides back and forth along the frame. The stroke of the upper slider corresponds to the semi-cylindrical valve core rotating 180° around the valve stem. The extreme positions of the upper slider or the lower slider correspond to the semi-cylindrical valve core completely blocking the first sub-cavity and the second sub-cavity, respectively.

2. The wastewater treatment filtration device with online replaceable ultrafiltration membrane filter element according to claim 1, characterized in that: The upper side of the frame is provided with an upper main pipe, and one end of several upper branch pipes is connected to the upper main pipe. The other end of several upper branch pipes is connected to the upper end of the online replaceable ultrafiltration membrane filter module through a switchable three-way valve. The upper main pipe is provided with an upper main pipe valve. The lower side of the frame is provided with a lower main pipe, and one end of several lower branch pipes is connected to the lower main pipe. The other end of several lower branch pipes is connected to the lower end of the online replaceable ultrafiltration membrane filter module through a switchable three-way valve. The lower main pipe is provided with a lower main pipe valve.

3. A wastewater treatment filtration device with an online replaceable ultrafiltration membrane filter element according to claim 1, characterized in that: The frame has several upper slide rails on its upper side, which are arranged in the front-to-back direction. The upper slide block of the online replaceable ultrafiltration membrane filter module is slidably mounted on the upper slide rail. The frame has several lower slide rails on its lower side, which are arranged in the front-to-back direction. The lower slide block of the online replaceable ultrafiltration membrane filter module is slidably mounted on the lower slide rail. Positioning bolts are provided between the upper slide block and the upper slide rail, and between the lower slide block and the lower slide rail.

4. A wastewater treatment filtration device with an online replaceable ultrafiltration membrane filter element according to claim 1, characterized in that: The upper end of the main interface is a cylindrical hole structure, and the lower end of the main interface is a frustum-shaped structure with a diameter that gradually increases from top to bottom, and the diameter of the lower end of the frustum-shaped structure is smaller than the diameter of the cylindrical cavity.

5. A wastewater treatment filtration device with an online replaceable ultrafiltration membrane filter element according to claim 1, characterized in that: The upper end of the water-dividing cavity is a frustum-shaped structure with a diameter that gradually decreases from top to bottom, and the diameter of the upper end of the frustum-shaped structure is smaller than the diameter of the cylindrical cavity. The lower end of the water-dividing cavity is a cylindrical hole structure.

6. A wastewater treatment filtration device with an online replaceable ultrafiltration membrane filter element according to claim 1, characterized in that: The partition is arranged in the water distribution cavity along the front-to-back direction. The front and back edges of the partition match the shape of the inner wall of the water distribution cavity and the front and back edges of the partition are fixed to the inner wall of the water distribution cavity, dividing the water distribution cavity into a first sub-cavity and a second sub-cavity. A cylindrical sleeve is arranged in the middle of the partition. The inner diameter of the cylindrical sleeve matches the outer diameter of the valve stem, and the valve stem is rotatably arranged in the cylindrical sleeve.

7. A wastewater treatment filtration device with an online replaceable ultrafiltration membrane filter element according to claim 6, characterized in that: A small semi-cylindrical structure is provided at the lower center of the rectangular surface of the semi-cylindrical valve core. The rectangular surface of the small semi-cylindrical structure coincides with and is fixed to the rectangular surface of the semi-cylindrical valve core. The upper end of the valve stem is fixed at the lower center of the small semi-cylindrical structure and the semi-cylindrical valve core, and the diameter of the valve stem is smaller than the diameter of the small semi-cylindrical structure.

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