Rainwater burying integrated machine

Abstract

The application relates to the technical field of rainwater treatment, and particularly discloses a rainwater buried integrated machine, which comprises a box body and a filter tank arranged in the box body, wherein the filter tank comprises a tank body, a water inlet pipe, a water outlet pipe and a blowdown pipe which are communicated between the top of the tank body and the box body; a plurality of filter screens are arranged in the tank body along the height direction of the tank body, a plurality of filter cavities are formed between the filter screens, the middle parts of all the filter screens below the uppermost filter screen are provided with upwardly-protruding circular tables, the top surfaces of the circular tables are provided with filter holes, a plurality of specifications of fillers are respectively filled between the plurality of filter cavities, the granularity of the fillers in the plurality of filter cavities gradually decreases from top to bottom, when back flushing is performed, the blocking piece is opened, water flow can directly pass through the filter holes on the circular tables, the scraped fillers are scraped to the circular tables by the scraper group during the rotating process, the flow speed of the water flow at the circular tables is greater than the flow speed of the water flow at the filter screens, so that a relatively strong impact force is caused on the fillers on the circular tables.

Description

Technical Field

[0001] This invention relates to the field of rainwater treatment technology, specifically to an integrated underground rainwater treatment machine. Background Technology

[0002] Chinese patent document CN106310742B discloses a swirl-surface water distribution type multi-media filter, including a tank, a media filter layer inside the tank, a bracket, a filter screen at the bottom of the bracket, and several layers of staggered "well"-shaped baffles on the bracket, with filter media filling the compartments of the "well"-shaped baffles; the water inlet pipe extends into the upper end cap and connects to a water distribution device, which includes a conical cylinder that gradually increases in size, several swirl water distribution plates arranged around the center of the cylinder to evenly distribute the water along the circumference of the plate, and a central baffle plate. The swirl water distribution plates radiate from the water inlet point to the surrounding area, with the center being higher and the periphery lower.

[0003] In current multi-layer media sand filters, when the pressure difference at the filter layer inlet exceeds a preset value, backwashing is triggered to prevent the packing layer from clogging and affecting efficiency. During backwashing, the upper surface of the packing mainly traps large suspended particles, forming a "filter cake layer," which requires a high impact force to remove. The lower packing adsorbs fine particles and colloids, and the dirt has strong adhesion, requiring a continuous and stable impact force to clean it. However, the impact force on the upper surface of the packing layer is usually lower than that on the lower packing, which leads to poor backwashing effect. Summary of the Invention

[0004] This invention provides an integrated rainwater underground filling machine, which aims to solve the problem in related technologies that the impact force on the upper surface of the filling layer is usually lower than that on the lower filling layer.

[0005] A rainwater underground integrated machine includes a housing and a filter tank disposed within the housing, the filter tank comprising:

[0006] The tank body has an inlet pipe, an outlet pipe, and a sewage pipe connecting the top to the box body;

[0007] Multiple filter screens are installed inside the tank along the height direction, forming multiple filter chambers between the filter screens. The middle of all the filter screens below the topmost filter screen is provided with an upward-protruding truncated cone, and the top surface of the truncated cone has filter holes.

[0008] Multiple sizes of packing materials are filled between multiple filter chambers. The particle size of the packing materials in the multiple filter chambers gradually decreases from top to bottom. There is a gap between the top surface of each layer of packing material and the top surface of the filter chamber.

[0009] A water distributor is installed at the bottom of the tank, and the water distributor is connected to the water outlet pipe through the water distribution pipe.

[0010] Multiple scraping components are respectively set on the bottom surface of all the filter screens above the bottom filter screen. The scraping components include a scraper assembly that can rotate along the filter screen and a sealing element that can block the filter holes on the truncated cone. When backflushing, the sealing element opens, and the water flow velocity through the filter holes on the truncated cone is greater than the water flow velocity through the filter screen. The scraper assembly scrapes the packing material located on the upper layer in the filter chamber onto the truncated cone.

[0011] Its effect is as follows: when backflushing, the sealing parts open, and the water can flow directly through the filter holes on the platform. At the same time, as the scraper assembly rotates, it scrapes the scraped packing onto the platform. The flow velocity of the water at the platform is greater than that at the filter screen, which creates a strong impact force on the packing on the platform and improves the backflushing effect.

[0012] Preferably, let the volume of the packing layer be V, the radius of the filter screen be R, the height of the frustum be h, the radius be r, and the radius of the water distribution pipe be x. Then 0 < [V - πh(R² - r²)] / π(r² - x²) < h, which ensures that even if the packing material beyond the plane of the upper surface of the frustum is completely scraped onto the frustum, the thickness of the packing material on the frustum is still less than h, thereby increasing the flow velocity of the water passing through the frustum.

[0013] In specific embodiments, the shape and material of the tank can be selected according to actual needs. For example, the tank can adopt a cylindrical design, and the material can be corrosion-resistant materials such as stainless steel to improve the durability and service life of the equipment. At the same time, the connection methods and sealing performance of pipes such as inlet pipes, outlet pipes, and sewage pipes also need to be strictly designed and tested to ensure the overall performance and safety of the equipment.

[0014] Preferably, the scraping assembly includes a rotating disk coaxially fixedly connected to the water distribution pipe. Multiple outer scrapers and multiple inner scrapers are installed on the rotating disk. The length direction of the outer scrapers is tangent to the frustum. The inner end of the inner scrapers is in contact with the water distribution pipe. One end of the water distribution pipe extends out of the tank and is connected to a drive device for driving its rotation. When scraping, the bottom of the outer scraper is flush with the top surface of the frustum.

[0015] Preferably, both the outer scraper and the inner scraper are perforated plates, which can reduce the weight of the scraping assembly, while increasing the flow area of ​​water when it passes through the scraping assembly, reducing water flow resistance, and avoiding greater resistance during rotation.

[0016] Preferably, the top of the outer scraper is hinged to the rotating disk, and the rotating disk is provided with a limiting structure for limiting the rotation angle of the outer scraper. During backflushing, the limiting structure keeps the outer scraper in a vertical state, and the bottom of the outer scraper is flush with the top surface of the frustum. After the backflushing is completed, the rotating disk rotates in the opposite direction, and the limiting structure makes the outer scraper tilt itself, with the bottom of the outer scraper located above the top surface of the frustum, thereby flattening the filler that exceeds the top surface of the frustum.

[0017] Preferably, the limiting structure includes a limiting block one and a limiting block two respectively disposed on both sides of the hinge between the rotating disk and the outer scraper. The side of the limiting block one near the outer scraper is a vertical surface, and the side of the limiting block two near the outer scraper is an inclined surface. During backflushing, the outer scraper is in close contact with the limiting block one due to the resistance, thus maintaining a vertical state. After the backflushing is completed, the rotating disk rotates in the opposite direction, and the outer scraper rotates due to the resistance, thus being in close contact with the limiting block two. The bottom of the outer scraper is lifted, so that the top filler is scraped flat.

[0018] Preferably, the sealing component includes a fixed ring fixedly installed on the inner wall of the truncated cone, a rubber ring slidably installed on the water distribution pipe, the rubber ring being located above the fixed ring, the outer diameter of the rubber ring being larger than the inner diameter of the fixed ring, and a limiting ring provided at the bottom of the inner top wall of the truncated cone to prevent the rubber plate from sticking to the filter holes.

[0019] Preferably, the filter screen is provided with multiple support members at its edge, and the inner wall of the tank is provided with mounting holes for connecting with the support members.

[0020] Preferably, the support is a spring pin that is slidably installed at the edge of the filter screen, and the outer end of the spring pin is adapted to the mounting hole.

[0021] By adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0022] When backwashing begins, the outer and inner scrapers rotate, scraping the packing material with more impurities on its upper surface towards the truncated cone. This concentrates the packing material above the truncated cone, allowing the high-speed water flow through the cone to thoroughly wash away the packing material with more impurities. After backwashing ends, the rotating disc rotates in the opposite direction, causing the outer and inner scrapers to rotate. The rotation of the outer scraper raises its bottom, creating a gap between it and the plane where the top surface of the truncated cone is located. This allows the top packing material to be scraped flat and filled into the gap, ensuring smooth operation for the next filtration cycle. This setup effectively cleans the packing material with more impurities on its upper surface, improving the backwashing cleaning effect. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention.

[0024] Figure 2 This is a schematic diagram of the tank body of the present invention.

[0025] Figure 3 This is a cross-sectional view of the interior of the tank body of the present invention.

[0026] Figure 4 This is a schematic diagram of the filter screen in this invention.

[0027] Figure 5 This is a schematic diagram of the rotating disk in this invention.

[0028] Figure 6This is a schematic diagram of the scraper assembly in this invention.

[0029] Figure 7 This is a schematic diagram of the structure of the frustum in this invention.

[0030] Figure label:

[0031] 1. Tank body; 11. Inlet pipe; 12. Outlet pipe; 13. Sewage pipe; 2. Filter screen; 21. Frustum; 22. Spring pin; 3. Water distributor; 4. Water distribution pipe; 5. Scraper assembly; 51. Scraper assembly; 511. Rotary disc; 5111. Limiting block one; 5112. Limiting block two; 512. Outer scraper; 513. Inner scraper; 52. Sealing component; 521. Fixing ring; 522. Rubber ring; 53. Drive device; 531. Rotary drive source; 532. Transmission mechanism. Detailed Implementation

[0032] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0033] like Figure 1 and Figure 2 As shown, a rainwater underground integrated machine includes a housing and a filter tank. The filter tank is connected to the housing by an inlet pipe 11, an outlet pipe 12 and a sewage pipe 13, so that rainwater is introduced into the housing through the inlet pipe 11, filtered by the filter tank and discharged through the outlet pipe 12.

[0034] like Figures 1-4As shown, the filter tank includes a tank body 1, four filter screens 2, three types of packing material, three scraper assemblies 5, a water distributor 3, and a water distribution pipe 4. The top of the tank body 1 is connected to the inlet pipe 11 and the drain pipe 13 via a three-way valve. The four filter screens 2 are installed inside the tank body 1 and are evenly spaced along the height of the tank body 1. The four filter screens 2 form an upper filter chamber, a middle filter chamber, and a lower filter chamber from top to bottom. The three types of packing material are filled into the upper filter chamber, the middle filter chamber, and the lower filter chamber in descending order of particle size. There is a gap between the upper surface of the packing material layer and the filter screen 2 above it. The scraper assemblies 5 are installed in the gaps. The water distribution pipe 4 is connected to the outlet pipe 12, and the axis of the water distribution pipe 4 is parallel to the tank body 1. The axes are collinear, and the water distribution pipe 4 passes through all the filter screens 2. The water distributor 3 is installed at the bottom of the water distribution pipe 4. During filtration, the three-way valve connects the tank 1 to the inlet pipe 11. Rainwater enters the tank 1 through the inlet pipe 11 and then passes through the upper filter chamber, middle filter chamber and lower filter chamber in sequence to complete filtration. Finally, it enters the water distributor 3 and is discharged through the water distribution pipe 4 and the outlet pipe 12. When backflushing, the three-way valve connects the tank 1 to the drain pipe 13. Clean water enters the water distribution pipe 4 through the outlet pipe 12 and finally enters the tank 1 from the water distributor 3. Then the clean water rises to backflush the packing. At the same time, the scraper assembly 5 scrapes the material on the upper surface of the packing layer to prevent the material on the upper surface from caking and becoming difficult to clean.

[0035] like Figure 3 and Figure 7 As shown, all filter screens 2 below the topmost filter screen 2 are provided with an upwardly protruding truncated cone 21 in the middle. The top surface of the truncated cone 21 is provided with filter holes. During backflushing, the scraping assembly 5 scrapes the filler that exceeds the plane of the upper surface of the truncated cone 21 toward the truncated cone 21, so that the filler on the upper surface gathers above the truncated cone 21.

[0036] Let the volume of the packing layer be V, the radius of the filter screen 2 be R, the height of the frustum 21 be h, the radius be r, and the radius of the water distribution pipe 4 be x. Then, the packing material exceeding the plane of the upper surface of the frustum 21 is V' = [V - πh(R² - r²)], and 0 < [V - πh(R² - r²)] / π(r² - x²) < h. Even if the packing material exceeding the plane of the upper surface of the frustum 21 is completely scraped onto the frustum 21, the thickness of the packing material on the frustum 21 is still less than h. Therefore, when the purified water rises for backwashing, it is divided into two water flows. The water flow velocity through the frustum 21 is greater than the water flow velocity through the filter screen 2. Therefore, the packing material with more attached impurities can be concentrated in the fast water flow zone for thorough rinsing.

[0037] like Figures 1-6As shown, the scraping assembly 5 includes a drive device 53, a scraper assembly 51, and a sealing element 52. The sealing element 52 is installed inside the truncated cone 21. During backwashing, the drive device 53 drives the scraper assembly 51 to rotate, and the scraper assembly 51 scrapes the packing material on the upper surface of the packing layer onto the truncated cone 21. The sealing element 52 opens, allowing water to flow through the filter holes on the top surface of the truncated cone 21. When switching from backwashing to filtration, the scraper assembly 51 scrapes the packing material on the truncated cone 21 outward and flattens it. The sealing element 52 seals the inside of the truncated cone 21 to prevent water from flowing through the filter holes on the top surface of the truncated cone 21. Finally, the scraper assembly 51 stops operating.

[0038] The scraper assembly 51 includes a rotating disk 511, three outer scrapers 512, and three inner scrapers 513. Both the outer scrapers 512 and inner scrapers 513 are perforated plates (not shown in the figure). The rotating disk 511 is coaxially rotatably connected to the filter screen 2. The rotating disk 511 is slidably connected vertically to the water distribution pipe 4 (a slider is provided at the center of the rotating disk 511, and a groove along the length of the water distribution pipe 4 is opened on its outer surface, with the slider slidingly engaged in the groove). The three outer scrapers 512 are hinged to the bottom surface of the rotating disk 511. The rotating disk 511 is provided with a limiting structure to restrict the rotation angle of the outer scrapers 512. The length direction of the outer scrapers 512 is tangent to the frustum 21. The three inner scrapers 512... 13 is fixedly installed in the middle of the rotating disk 511. The inner end of the inner scraper 513 is in contact with the water distribution pipe 4, and the inner scraper 513 is arc-shaped. During backflushing, the limiting structure keeps the outer scraper 512 in a vertical state. The bottom of the outer scraper 512 is flush with the top surface of the truncated cone 21, thereby scraping the packing on the upper surface of the packing layer onto the truncated cone 21. The packing gathers on the inner arc surface of the inner scraper 513, thereby reducing the packing being thrown out. After the backflushing is completed, the rotating disk 511 rotates in the opposite direction. The limiting structure makes the outer scraper 512 tilt itself, thereby lifting the bottom of the outer scraper 512. The inner scraper 513 scrapes the packing above the truncated cone 21 out of the truncated cone 21, and the outer scraper 512 flattens the packing.

[0039] The limiting structure includes a limiting block 1 5111 and a limiting block 2 5112 fixedly installed at the bottom of the rotating disk 511. The limiting blocks 1 5111 and 2 5112 are respectively located on both sides of the hinge between the rotating disk 511 and the outer scraper 512. The side of the limiting block 1 5111 near the outer scraper 512 is a vertical surface, and the side of the limiting block 2 5112 near the outer scraper 512 is an inclined surface. During backflushing, the outer scraper 512 is in close contact with the limiting block 1 5111 due to the resistance, thus maintaining a vertical state. After the backflushing is completed, the rotating disk 511 rotates in the opposite direction, and the outer scraper 512 rotates due to the resistance, thus being in close contact with the limiting block 2 5112. The bottom of the outer scraper 512 is lifted, so that the top filler is scraped flat.

[0040] The sealing component 52 includes a fixed ring 521 and a rubber ring 522. The fixed ring 521 is fixedly installed on the inner wall of the frustum 21, and the rubber ring 522 is slidably installed on the water distribution pipe 4, with the rubber ring 522 located above the fixed ring 521. The outer diameter of the rubber ring 522 is larger than the inner diameter of the fixed ring 521. A limiting ring is provided at the bottom of the inner top wall of the frustum 21. When filtration is performed, the water flows from top to bottom, thereby pushing the rubber plate to contact the fixed ring 521, thus closing the channel inside the frustum 21. When backflushing is performed, the water flows from bottom to top, pushing the rubber ring 522 to contact the limiting ring, thereby forming a channel between the rubber plate and the fixed ring 521, and the rubber ring 522 does not contact the inner top wall of the frustum 21, allowing the water to pass through the filter holes on the frustum 21 from bottom to top.

[0041] The drive unit 53 includes a rotary drive source 531 installed inside the housing. The water distribution pipe 4 extends out of the top of the filter tank. The top of the water distribution pipe 4 is closed, and a transmission mechanism 532 (e.g., a belt and pulley mechanism) is installed between it and the rotary drive source 531. A connecting hole is opened on the part of the water distribution pipe 4 located inside the filter tank. A rotary joint is installed on the connecting hole. Therefore, the water distribution pipe 4 and the water outlet pipe 12 are connected through a rotary structure. When the rotary drive source 531 is started, the water distribution pipe 4 is controlled to rotate through the transmission mechanism 532, thereby causing the rotating disk 511 to rotate with the outer scraper 512 and the inner scraper 513.

[0042] To facilitate the installation and replacement of the filter screen 2, multiple spring pins 22 are provided at the edge of the filter screen 2. The inner wall of the tank body 1 is provided with mounting holes for connection with the support. The filter screen 2 is provided with a reinforcing rod, and the spring pins 22 are slidably installed on the reinforcing rod. The outer end of the spring pin 22 is adapted to the mounting hole. When installing, the spring pin 22 is retracted into the reinforcing rod, and then the filter screen 2 is slid downward. When the spring pin 22 is aligned with the mounting hole, the spring pin 22 pops out, thereby fixing the filter screen 2 to the inner wall of the filter tank.

[0043] Working principle: In the rainwater treatment process, when rainwater enters the tank through the inlet pipe 11, it will undergo multi-layer filtration in the filter tank. First, the rainwater passes through the upper filter chamber, which is filled with packing material with larger particle size, which can initially remove large particulate impurities in the rainwater. Then, the rainwater enters the middle filter chamber and the lower filter chamber, which are filled with packing material with gradually decreasing particle size to further remove fine particles and colloids and other pollutants.

[0044] When backflushing begins, clean water enters the water distribution pipe 4 through the water outlet pipe 12 and is finally sprayed out from the water distributor 3 to rinse the packing material upwards. At this time, when the rotary drive source 531 is started, the water distribution pipe 4 is controlled to rotate through the transmission mechanism 532, so that the rotating disk 511 rotates with the outer scraper 512 and the inner scraper 513, scraping the material on the upper surface of the packing layer towards the frustum 21, so that the material is concentrated above the frustum 21.

[0045] Because the top surface of the truncated cone 21 has filter holes and the water flows from bottom to top, the water flow pushes the rubber ring 522 to contact the limiting ring, thereby forming a channel between the rubber plate and the fixed ring 521. The rubber ring 522 does not contact the inner top wall of the truncated cone 21, allowing the water to pass through the filter holes on the truncated cone 21 from bottom to top. Therefore, the water flow velocity through the truncated cone 21 is greater than the water flow velocity through the filter screen 2. This design ensures that the filler with more attached impurities is concentrated in the fast water flow area, thereby getting more thorough rinsing. At the same time, the design of the scraper assembly 51 also takes into account the uniform distribution of the filler.

[0046] After the backflushing is completed, the rotating disk 511 rotates in the opposite direction with the outer scraper 512 and the inner scraper 513. The outer scraper 512 rotates due to the resistance, thus sticking tightly to the limiting block 5112. The bottom of the outer scraper 512 is raised, forming a material gap between it and the plane where the top surface of the truncated cone 21 is located, so that the top packing is scraped flat and filled into the material gap to ensure the smooth operation of the next filtration.

[0047] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A rainwater burying integrated machine comprising a box body and a filter tank arranged in the box body, characterized in that, The filter tank includes: The tank (1) has an inlet pipe (11), an outlet pipe (12) and a drain pipe (13) connected between its top and the box. Multiple filter screens (2) are set inside the tank (1) along the height direction of the tank (1). Multiple filter chambers are formed between the filter screens (2). A convex truncated cone (21) is provided in the middle of all the filter screens (2) below the uppermost filter screen (2). Filter holes are opened on the top surface of the truncated cone (21). Multiple sizes of packing materials are filled between multiple filter chambers. The particle size of the packing materials in the multiple filter chambers gradually decreases from top to bottom. There is a gap between the top surface of each layer of packing material and the top surface of the filter chamber. A water distributor (3) is installed at the bottom of the tank (1), and the water distributor (3) is connected to the water outlet pipe (12) through a water distribution pipe (4); Multiple scraping components (5) are respectively set on the bottom surface of all filter screens (2) above the bottommost filter screen (2). The scraping component (5) includes a scraper assembly (51) that can rotate along the filter screen (2) and a sealing member (52) that can block the filter holes on the truncated cone (21). When backflushing, the sealing member (52) opens, and the water flow velocity through the filter holes of the truncated cone (21) is greater than the water flow velocity through the filter screen (2). The scraper assembly (51) scrapes the packing material located in the upper layer of the filter chamber onto the truncated cone (21).

2. The integrated rainwater underground drainage system according to claim 1, characterized in that, Let the volume of the packing layer be V, the radius of the filter screen (2) be R, the height of the frustum (21) be h, the radius be r, and the radius of the water distribution pipe (4) be x. Then 0 < [V - πh(R² - r²)] / π(r² - x²) < h.

3. The integrated rainwater underground drainage system according to claim 2, characterized in that, The scraping assembly (5) includes a rotating disk (511) coaxially rotatably connected to the filter screen (2). The rotating disk (511) is slidably connected to the water distribution pipe (4). Multiple outer scrapers (512) and multiple inner scrapers (513) are installed on the rotating disk (511). The length direction of the outer scraper (512) is tangent to the frustum (21). The inner end of the inner scraper (513) is in contact with the water distribution pipe (4). One end of the water distribution pipe (4) passes through the tank (1) and is connected to a drive device (53) for driving its rotation. When scraping, the bottom of the outer scraper (512) is flush with the top surface of the frustum (21).

4. The integrated rainwater underground drainage system according to claim 3, characterized in that, Both the outer scraper (512) and the inner scraper (513) are perforated plates.

5. The integrated rainwater underground drainage system according to claim 4, characterized in that, The inner end of the outer scraper (512) is offset from the outer end of the inner scraper (513).

6. The integrated rainwater underground drainage system according to claim 4, characterized in that, The top of the outer scraper (512) is hinged to the rotating disk (511), and the rotating disk (511) is provided with a limiting structure for limiting the rotation angle of the outer scraper (512). When backflushing, the limiting structure keeps the outer scraper (512) in a vertical state, and the bottom of the outer scraper (512) is flush with the top surface of the frustum (21). After the backflushing is completed, the rotating disk (511) rotates in the opposite direction, and the limiting structure makes the outer scraper (512) tilt itself. The bottom of the outer scraper (512) is located above the top surface of the frustum (21), thereby flattening the filler that exceeds the top surface of the frustum (21).

7. The integrated rainwater underground drainage system according to claim 6, characterized in that, The limiting structure includes limiting block one (5111) and limiting block two (5112) respectively set on both sides of the hinge between the rotating disk (511) and the outer scraper (512). The side of limiting block one (5111) near the outer scraper (512) is a vertical surface, and the side of limiting block two (5112) near the outer scraper (512) is an inclined surface.

8. The integrated rainwater underground drainage system according to claim 6, characterized in that, The sealing component (52) includes a fixing ring (521) fixedly installed on the inner wall of the truncated cone (21), a rubber ring (522) slidably installed on the water distribution pipe (4), the rubber ring (522) being above the fixing ring (521), the outer diameter of the rubber ring (522) being larger than the inner diameter of the fixing ring (521), and a limiting ring for preventing the rubber plate from sticking to the filter hole at the bottom of the inner top wall of the truncated cone (21).

9. The integrated rainwater underground drainage system according to claim 1, characterized in that, The filter screen (2) has multiple support members at its edge, and the inner wall of the tank (1) has mounting holes for connecting with the support members.

10. The integrated rainwater underground drainage system according to claim 9, characterized in that, The support is a spring pin (22) that is slidably installed on the edge of the filter screen, and the outer end of the spring pin (22) is adapted to the mounting hole.

Images