A sealing cap for a silent drain

Abstract

This invention provides a sealing cap for silent drainage pipes, belonging to the field of building materials technology. It solves the problem of improving maintenance convenience while ensuring sealing and noise reduction effects. In this sealing cap for silent drainage pipes, the silent drainage pipe includes a pipe body with a maintenance channel. The sealing cap includes an outer cover and a piston embedded in the maintenance channel, with its inner end face flush with the inner end port of the maintenance channel. The outer cover and the pipe body are screwed together to seal the outer end port of the maintenance channel. The outer end face of the piston has several T-shaped posts. A push plate is slidably connected inside the maintenance channel, and the push plate is sleeved on the outside of each T-shaped post, abutting against the inner bottom wall of the outer cover. One T-shaped post extends out of the outer cover and abuts against the outer wall of the outer cover. Some or all of the T-shaped posts are sleeved with springs, and each spring elastically acts between the piston and the push plate. This sealing cap for silent drainage pipes can improve maintenance convenience while ensuring sealing and noise reduction effects.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology and relates to a sealing cap for silent drainage pipes. Background Technology

[0002] Silent drainage pipes are a common type of pipe in modern life. Compared with ordinary drainage pipes, they can reduce the noise generated when water flows through them, making them one of the most widely used pipe materials in the building materials industry.

[0003] The existing technology offers a variety of shapes for silent drainage pipes, designed to meet different renovation needs. One type is the silent drainage pipe with an inspection port. Due to the presence of the inspection port, when there is a blockage in the pipe, the plug installed at the inspection port can be removed, and the blockage in the pipe can be cleared through the inspection port, thereby achieving the purpose of unblocking the pipe.

[0004] To ensure the quiet performance of the silent drainage pipe, the design of the plug structure also has certain requirements. For example, the PVC drain pipe with anti-clogging sewage device disclosed in Chinese Patent (Authorization Announcement No.: CN205479907U) includes a pipe body made of PVC material with an inspection hole, an inspection pipe, a push-pull rod with a piston at the front end, and a fixing cap with a square groove. The rear end of the push-pull rod is fixed to the bottom of the square groove. The front end of the inspection pipe is connected to the inspection hole, and the axis of the pipe body is perpendicular to the axis of the inspection pipe. The outer wall of the rear end of the inspection pipe has a square cross-section, and the fixing cap is placed on the rear end of the inspection pipe through the square groove and fixed by fasteners. The piston is set against the inner wall of the inspection pipe and placed on the inspection hole. The piston has an arc-shaped surface that matches the inner wall of the pipe and can be pushed and pulled along the axial direction of the inspection pipe by the push-pull rod inside the inspection pipe. A valve is also provided on each side of the pipe body near the inspection hole. (This is in conjunction with paragraphs 0018-0020 of the specification and the appendix.) Figure 1 It is known that the user pushes the push-pull rod and piston to slide inside the inspection tube by using the fixing cap, and uses the inner end face of the piston and the wall of the inspection hole to reconstruct the inner surface of the tube body, and uses bolts to lock the fixing cap to achieve the positioning of the push-pull rod and piston.

[0005] However, in practice, the use of this structure is quite inconvenient. Specifically, the installation location of the silent drainage pipe is generally relatively close to the corner, such as the narrow space above the ceiling panel. When maintenance is required, for the above structure, before pulling out the fixing cap, the user needs to unscrew the bolt from the positioning hole. However, it is difficult to operate in the narrow space, making maintenance extremely inconvenient and causing great inconvenience to the maintenance work. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a sealing cap for silent drainage pipes. The technical problem to be solved by this invention is: how to improve the convenience of maintenance while ensuring both sealing and noise reduction effects.

[0007] The objective of this invention can be achieved through the following technical solution: a sealing cover for a silent drain pipe, the silent drain pipe including a pipe body with an inspection channel, the sealing cover including an outer cover and a piston embedded in the inspection channel with its inner end face flush with the inner end port of the inspection channel, characterized in that the outer cover and the pipe body are screwed together and the outer end port of the inspection channel is sealed, the outer end face of the piston has a plurality of T-shaped posts, a push plate is slidably connected in the inspection channel, the push plate is sleeved on the outside of each of the T-shaped posts and abuts against the inner bottom wall of the outer cover, one of the T-shaped posts extends out of the outer cover and abuts against the outer wall of the outer cover, some or all of the T-shaped posts are sleeved with springs, and each spring elastically acts between the piston and the push plate.

[0008] In this design, the maintenance channel on the pipe body provides an operational route for pipe dredging and maintenance. The sealing cap, as a supporting structure for the pipe body, specifically includes an outer cover, a push plate, a piston, and several springs. The outer cover is fixed to the pipe body by screws, allowing for assembly and disassembly without bolts or tools, significantly improving operational convenience in confined spaces. The piston is embedded in the maintenance channel and forms a linkage with the push plate through a T-shaped post. Specifically, the T-shaped post at the center extends outward, passing through the push plate and extending out of the outer cover to abut against the outer wall, achieving assembly positioning and anti-displacement functions. The spring is sleeved on the T-shaped post and elastically supports the piston between the piston and the push plate, ensuring the piston always tends to press inward. In actual use, maintenance personnel insert the piston into the outer end port of the maintenance channel, ensuring the internal thread of the outer cover contacts the external thread on the outer wall of the tube. The outer cover is screwed tightly onto the tube via this threaded engagement, sealing the outer end port of the maintenance channel. Simultaneously, the push plate, acting as the force transmission component, contacts the inner bottom wall of the outer cover on one side and the springs on the other, thus applying force along the center of the maintenance channel to the springs during the tightening process of the outer cover. The linear inward pressure causes the spring to contract and deform under continuous pressure, applying an inward elastic force to the outer end of the piston. The piston is continuously compressed inward by this elastic force until its inner end face is flush with the inner end port of the maintenance channel. This state is considered the piston properly installed. The cooperation between the inner end face of the piston and the inner end port of the maintenance channel reconstructs a smooth arc surface inside the pipe, ensuring a smooth connection with the inner wall of the drain pipe and preventing pits or protrusions at the inner end port of the maintenance channel, thus preventing noise caused by water flow impact. Each T-shaped column serves as a guide post, a spring mounting post, and a positioning support post, achieving three functions in one device. This significantly reduces the number of parts, making the overall structure more compact and space-saving, making it particularly suitable for installation in confined spaces. It is worth mentioning that when rotating the outer cover, whether it is screwed inward or outward, the outer cover applies pressure to each spring through the push plate. If there were no push plate, and the inner wall of the outer cover directly contacts one end of the spring, the end of the spring in contact with it would be continuously subjected to rotational force along the circumference of the outer cover during the screwing process. Even if each spring is sleeved outside each T-shaped post, after repeated use, the deformation of the spring is very likely to cause uneven force on the piston in the circumferential direction, resulting in different embedment depths of the piston front end. In view of this defect, this application sets a push plate in the outer cover. During the screwing process, the contact part between the push plate and the inner wall of the outer cover bears and absorbs the circumferential force of the outer cover rotation, and then provides a stable axial force to each spring through its other side. This avoids the springs from being subjected to axial pressure and circumferential torque at the same time, which would cause irregular deformation. This ensures that the sealing cover can still be installed in place after multiple disassemblies and reassemblies, effectively guaranteeing the noise reduction effect of the silent drain pipe.

[0009] In the aforementioned sealing cap for a silent drain pipe, the T-shaped posts include T-shaped post one and T-shaped post two. T-shaped post one is located at the center of the piston end face. The T-shaped post two are distributed circumferentially around the T-shaped post one. Each T-shaped post two is fitted with a spring. The piston's outer end face has several limiting grooves, each corresponding to one of the T-shaped post two. One end of each spring is embedded in its respective limiting groove, and the other end abuts against the inner side of the push plate. T-shaped post one serves as the central positioning post, providing guidance, positioning, and limiting functions. The T-shaped post two are evenly distributed around the center, forming a multi-point elastic support structure, ensuring uniform force on the piston and preventing problems such as unilateral tilting, jamming, or incomplete sealing. One end of the spring is embedded in the limiting groove on the piston end face to achieve radial positioning and prevent it from falling off, thus avoiding spring displacement, tilting, or failure during extension and contraction. The other end is stably supported on the inner side of the push plate, so that the elastic force is evenly transmitted to the outer circumference of the piston, ensuring balanced sealing force and improving sealing reliability and structural stability. Furthermore, the circumferentially evenly arranged multiple springs allow the piston to automatically align and center itself. Even if there is a slight misalignment during installation, the spring force can automatically correct the piston to the centered position, eliminating the need for manual alignment, significantly reducing assembly difficulty, and preventing abnormal noise and wear caused by one-sided piston friction.

[0010] In the aforementioned sealing cover for a silent drain pipe, the push plate has a first through hole, and the outer cover has a second through hole. A first T-shaped post passes through both the first and second through holes, with its outer peripheral wall fitting against the inner peripheral walls of both holes. The push plate also has several third through holes, with several second T-shaped posts correspondingly passing through each of the third through holes, their outer peripheral walls fitting against the inner peripheral walls of the third through holes. The push plate and the outer cover form a precise guiding fit through the through holes and the T-shaped posts. Specifically, the first T-shaped post passes through the first and second through holes sequentially, with its outer peripheral wall fitting against the hole wall, achieving coaxial positioning and preventing radial swaying, eccentricity, or jamming of the push plate and piston during sliding. The two T-shaped columns are inserted into the three perforations to form multi-point synchronous guidance, which further improves the coaxiality and smoothness of the piston and push plate movement, ensuring that the piston always moves stably along the maintenance channel axis during extension, retraction and reset, and will not have problems such as swaying or scraping the inner wall that affect sealing and noise reduction.

[0011] In the aforementioned sealing cover for a silent drain pipe, the outer side of the push plate has an annular protrusion surrounding the perforation. The inner peripheral wall of the annular protrusion fits against the outer peripheral wall of the T-shaped post, and the push plate abuts against the inner bottom wall of the outer cover through the annular protrusion. The annular protrusion on the push plate surrounding the perforation serves two purposes: firstly, it lengthens the mating length with the T-shaped post, improving guiding accuracy and resistance to eccentric loads, and preventing the push plate from tilting under stress; secondly, the annular protrusion abuts against the inner bottom wall of the outer cover, forming an annular contact support, ensuring even distribution of top pressure, preventing localized stress concentration that could lead to deformation or damage to the push plate, and simultaneously ensuring more stable and reliable top pressure positioning of the push plate by the outer cover.

[0012] In the aforementioned sealing cap for a silent drain pipe, a retaining edge is provided at the inner end port of the inspection channel. The retaining edge is circumferentially arranged along the inner end port of the inspection channel, and a first stepped groove is formed at the outer edge of the inner end face of the piston. The retaining edge is embedded in the first stepped groove. The retaining edge at the inner end of the inspection channel and the first stepped groove on the piston form a fitting and positioning structure. The retaining edge is embedded in the first stepped groove, realizing circumferential limiting and radial positioning of the inner end of the piston. This accurately ensures that the inner end face of the piston is flush with the inner end port of the inspection channel, ensuring a smooth transition between the piston and the inner wall of the drain pipe, reducing water flow impact, turbulence, and vibration noise, while improving the accuracy and sealing of the sealing position.

[0013] In the aforementioned sealing cover for a silent drain pipe, a second stepped groove is provided near the center of the inspection channel. This groove runs circumferentially along the inner wall of the inspection channel. The outer end of the piston protrudes radially outward and is embedded in the second stepped groove. The second stepped groove provides space for the piston's outer end to be embedded, forming an axial limiting and radial sealing structure. This prevents the piston from moving excessively inward under spring force and limits radial wobble, ensuring overall assembly stability. The stepped structure creates multiple sealing barriers, improving the sealing effect, reducing water leakage and airflow noise, and further enhancing silent performance.

[0014] In the aforementioned sealing cover for a silent drain pipe, the inner wall of the inspection channel has several retaining ribs, each arranged axially along the inspection channel, and the retaining ribs are spaced apart circumferentially along the inspection channel. The outer wall of the piston has several guide grooves axially along the inspection channel, with each retaining rib and guide groove corresponding to and embedded therein. The retaining ribs on the inner wall of the inspection channel are evenly distributed axially, forming a sliding guide fit with the guide grooves on the outer wall of the piston. The retaining ribs embedded in the guide grooves ensure that the piston can only slide smoothly axially and cannot rotate circumferentially, preventing rotational displacement of the piston under water flow impact or spring extension / retraction. This ensures stable piston positioning, uniform sealing surface contact, improved sliding smoothness, and reduced risk of jamming.

[0015] In the aforementioned sealing cap for silent drain pipes, one end of each retaining rib is integrally connected to the retaining flange, and the other end is flush with the bottom wall of the second stepped groove. The two ends of the retaining rib are respectively integrated with the retaining flange and the second stepped groove, forming a continuous and stable reinforced skeleton structure. This not only enhances the overall structural strength of the maintenance channel and prevents deformation under pressure, but also provides stable axial guidance for the piston throughout its entire movement, ensuring a consistent sliding path from the outer end to the inner end of the piston, further improving motion smoothness and positioning accuracy.

[0016] In the aforementioned sealing cap for a silent drain pipe, an installation groove is provided on the outer wall of the piston's outer end. The installation groove is circumferentially oriented along the piston, and a sealing ring is embedded within it, abutting against the side wall of the second stepped groove. The installation groove on the piston's outer wall is used to securely install the sealing ring. The sealing ring is stably positioned and tightly abuts against the side wall of the second stepped groove, forming a circumferentially continuous elastic sealing structure. This effectively blocks water and air leakage from the gap between the piston and the maintenance channel, preventing water leakage, air leakage, and airflow noise. While ensuring sealing reliability, it further improves the noise reduction effect.

[0017] In the aforementioned sealing cap for a silent drain pipe, the outer end face of the outer cap has annular rib one and annular rib two. Annular rib one is located at the outer edge of the end face of the outer cap, and annular rib two is located inside annular rib one, both concentrically arranged around the perforation two. Annular rib two is provided with several elongated reinforcing ribs, which are spaced apart circumferentially along annular rib two. One end of each reinforcing rib is integrated with annular rib one, and the other end extends to the edge near the opening of the perforation two. The end face of the outer cap is provided with double-layered annular ribs and radial reinforcing ribs. Annular rib one and annular rib two form a concentric reinforcement structure. Combined with the circumferentially evenly distributed elongated reinforcing ribs, the overall strength and torsional and compressive resistance of the outer cap are greatly improved, preventing deformation and cracking during tightening or under stress. At the same time, the reinforcing ribs extend from the outer edge to the edge of the perforation two, effectively strengthening the central stress area, ensuring stable positioning of the T-shaped column one and the push plate, and extending the overall service life.

[0018] Compared with existing technologies, the sealing cap for silent drain pipes has the following advantages: it adopts a screw-on outer cap body with a spring-loaded automatic pressing structure, which can be quickly disassembled and assembled without bolts or tools. The piston end face is flush with the inspection channel port, and the inner wall transitions smoothly. With multiple sealing and guiding positioning structures, it provides a tight seal and high stability. The design is reinforced by multiple positioning features, including retaining ribs and guide grooves, stepped grooves and retaining edges, annular protrusions and multi-level ribs, which ensures smooth piston movement without deviation, rotation, or jamming, resulting in a longer service life. Attached Figure Description

[0019] Figure 1 This is a structural diagram of a sealing cap used for silent drain pipes.

[0020] Figure 2 This is a cross-sectional view of the sealing cap for silent drain pipes with the access passage open.

[0021] Figure 3 This is a schematic diagram of the overall structure of the sealing cap.

[0022] Figure 4 This is an exploded view of the sealing cap.

[0023] Figure 5 This is a schematic diagram of the piston structure.

[0024] Figure 6 This is a schematic diagram of the push plate structure.

[0025] Figure 7 This is a schematic diagram of the outer cover.

[0026] Figure 8 This is a cross-sectional view of the sealing cap for silent drain pipes with the maintenance passage closed.

[0027] Figure 9 This is a schematic diagram of the tube's structure.

[0028] In the picture:

[0029] 1. Pipe body; 11. Inspection passage; 12. Retaining edge; 13. Second step groove; 14. Retaining rib;

[0030] 2. Outer cover; 21. Perforation 2; 22. Circular rib 1; 23. Circular rib 2; 24. Reinforcing rib;

[0031] 3. Piston; 31. T-shaped post one; 32. T-shaped post two; 33. Limiting groove; 34. First step groove; 35. Guide groove; 36. Mounting groove; 361. Sealing ring;

[0032] 4. Push plate; 41. Perforation 1; 42. Perforation 3; 43. Annular protrusion;

[0033] 5. Spring. Detailed Implementation

[0034] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0035] like Figure 1 , Figure 2 , Figure 3 , Figure 8As shown, the sealing cap for the silent drain pipe includes a pipe body 1, and the sealing cap includes an outer cover 2, a piston 3, a push plate 4, and a spring 5. The shape of the pipe body 1 is not limited; in this embodiment, the pipe body 1 is a common four-way pipe with a cylindrical inspection channel 11 on its side wall for pipe unblocking and maintenance. The piston 3 is cylindrical and embedded in the inspection channel 11, with an arc-shaped inner end face. After installation, it remains flush with the inner end of the inspection channel 11, ensuring a smooth connection between the inner surface of the piston 3 and the inner wall of the drain pipe, avoiding protrusions or grooves that could cause water flow impact, vortices, and noise.

[0036] Combination Figure 4 and Figure 5 The outer cover 2 is threaded onto the outer end of the pipe body 1, sealing the port of the inspection channel 11. Tightening and loosening can be done by hand without screwdrivers, wrenches, or other tools, allowing for quick operation in confined spaces. The outer end face of the piston 3 has an integrally formed central T-shaped post 31 and multiple surrounding T-shaped posts 32. The push plate 4 is fitted onto each T-shaped post and can slide axially along the inspection channel 11. When the outer cover 2 is tightened, its inner bottom wall presses against the push plate 4, causing the push plate 4 to keep the piston 3 in the sealing position.

[0037] T-shaped posts 31 pass sequentially through perforations 41 on the push plate 4 and 21 on the outer cover 2, extending outwards to abut against the outer wall of the outer cover 2, achieving axial positioning and preventing misalignment. Multiple T-shaped posts 32 are fitted with springs 5. One end of the spring 5 is embedded in a limiting groove 33 on the outer end face of the piston 3 for positioning, while the other end presses against the inner side of the push plate 4, ensuring the piston 3 is always subjected to an inward elastic preload, guaranteeing a tight seal. After removing the outer cover 2, the elastic force of the springs 5 ​​weakens, and the outer wall of the outer cover 2 can engage with the large-diameter end of the T-shaped posts 31 to pull the piston 3 outwards, ensuring convenient disassembly and assembly.

[0038] Combination Figure 6An annular protrusion 43 is provided around the perforation 41 on the outer side of the push plate 4. This annular protrusion 43 fits closely to the outer peripheral wall of the T-shaped column 31 over a long distance, improving guiding accuracy. It also abuts against the inner bottom wall of the outer cover 2 through its annular surface, ensuring even distribution of top pressure and preventing deformation of the push plate 4. A retaining flange 12 is provided at the inner end port of the maintenance channel 11. A first stepped groove 34 is formed along the circumference of the inner edge of the piston 3. The retaining flange 12 is embedded in the first stepped groove 34, achieving precise positioning and ensuring that the end face of the piston 3 and the inner end port of the maintenance channel 11 remain flush. Secondly, a second stepped groove 13 is formed near the middle of the inner wall of the maintenance channel 11. The outer end of the piston 3 protrudes radially and is embedded in the second stepped groove 13, forming an axial limit for the piston 3 through this double fit. An installation groove 36 is formed along the circumference of the outer wall of the piston 3. A sealing ring 361 is installed in the groove. The sealing ring 361 is tightly abutted against the side wall of the second stepped groove 13, forming a circumferential seal to prevent water and air leakage and reduce noise.

[0039] Combination Figure 9 The inner wall of the maintenance passage 11 is provided with multiple axial retaining ribs 14, and the outer wall of the piston 3 is provided with corresponding guide grooves 35 along the axial direction. The retaining ribs 14 are embedded in the guide grooves 35, so that the piston 3 can only slide axially and cannot rotate, avoiding wobble, scratching and sealing failure. One end of the retaining rib 14 is connected to the retaining edge 12, and the other end is flush with the second step groove 13, forming an integral reinforced frame to improve structural strength and guiding stability.

[0040] Combination Figure 7 The outer end face of the outer cover 2 is provided with annular rib 1 22, annular rib 23 and multiple radial reinforcing ribs 24. The reinforcing ribs 24 connect the inner and outer annular ribs and extend to the edge of the perforation 21, which greatly improves the strength of the outer cover 2, prevents cracking and deformation when tightened, and extends the service life.

[0041] During daily use, as the outer cover 2 is tightened, it gradually pushes the push plate 4 inward. The compressed spring 5 presses the piston 3 into the sealing position, and the sealing ring 361 achieves a seal. The inner wall of the piston 3 is flush with the pipe, ensuring smooth water flow and low noise. When maintenance is required, the outer cover 2 can be unscrewed by hand. By using the outer end face of the outer cover 2 and the large-diameter end of the T-shaped post 31, the piston 3 can be pulled backward to expose the maintenance channel 11 for unblocking.

[0042] T-shaped post 31 and several T-shaped posts 32 can be detachably connected to the outer end of piston 3. Specifically, several threaded holes can be opened on the outer end face of piston 3 and screwed to each threaded hole.

[0043] Secondly, it is worth mentioning that in this embodiment, when the pipe body 1 is manufactured, the inner end port of the maintenance channel 11 is in a blocked state. In this state, when the sealing cover is assembled into the maintenance channel 11, the T-shaped post 31 protrudes further from the outer end face of the outer cover 2 because the inner end port of the maintenance channel 11 remains blocked. This means that when maintenance is required for the first time, the blocked portion needs to be manually opened. Figure 8 , Figure 9 As shown, a circular groove structure is provided on the outer wall of the sealing part, which can ensure that the maintenance personnel can chisel along the groove wall. This provides a chisel reference and can also appropriately weaken the structural strength in the middle through the existence of the groove, ensuring that the chisel shape is regular. After one maintenance, after the maintenance personnel assemble the sealing cover into the maintenance channel 11, since the inner end of the piston 3 is flush with the inner end port of the maintenance channel 11, the large diameter end of the T-shaped column 31 protrudes less from the outer end face of the outer cover body 2. This allows the maintenance personnel to judge whether the pipe body 1 has been maintained by the amount of protrusion of the T-shaped column 31.

[0044] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

[0045] Although this document frequently uses terms such as pipe body 1, inspection channel 11, retaining edge 12, second step groove 13, retaining rib 14, outer cover 2, perforation 21, annular rib 1 22, annular rib 23, reinforcing rib 24, piston 3, T-shaped post 1 31, T-shaped post 2 32, limiting groove 33, first step groove 34, guide groove 35, mounting groove 36, sealing ring 361, push plate 4, perforation 1 41, perforation 3 42, annular protrusion 43, and spring 5, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A sealing cap for a silent drain pipe, the silent drain pipe comprising a pipe body (1) having an inspection channel (11), the sealing cap comprising an outer cap body (2) and a piston (3) embedded in the inspection channel (11) with its inner end face flush with the inner end port of the inspection channel (11), characterized in that, The outer cover (2) and the tube (1) are screwed together and the outer end of the maintenance channel (11) is sealed. The piston (3) has several T-shaped columns on its outer end face. A push plate (4) is slidably connected inside the maintenance channel (11). The push plate (4) is sleeved on each of the T-shaped columns and abuts against the inner bottom wall of the outer cover (2). One of the T-shaped columns extends out of the outer cover (2) and abuts against the outer wall of the outer cover (2). Some or all of the T-shaped columns are sleeved with springs (5), and each spring (5) acts elastically between the piston (3) and the push plate (4).

2. The sealing cap for a silent drain pipe according to claim 1, characterized in that, The T-shaped columns include a first T-shaped column (31) and a second T-shaped column (32). The first T-shaped column (31) is located at the center of the end face of the piston (3). The second T-shaped columns (32) are distributed circumferentially around the first T-shaped column (31). Each second T-shaped column (32) is fitted with a spring (5). The piston (3) has a plurality of limiting grooves (33) on its outer end face. The limiting grooves (33) are arranged around each second T-shaped column (32) in a corresponding manner. One end of each spring (5) is embedded in each limiting groove (33), and the other end is pressed against the inner side of the push plate (4).

3. The sealing cap for a silent drain pipe according to claim 2, characterized in that, The push plate (4) has a through hole 1 (41) and the outer cover (2) has a through hole 2 (21). The T-shaped column 1 (31) passes through the through hole 1 (41) and the through hole 2 (21), and its outer peripheral wall is in contact with the inner peripheral wall of the through hole 1 (41) and the through hole 2 (21). The push plate (4) also has several through holes 3 (42), and several T-shaped columns 2 (32) are passed through each of the through holes 3 (42) in a corresponding manner, and their outer peripheral walls are in contact with the inner peripheral walls of the through holes 3 (42).

4. The sealing cap for a silent drain pipe according to claim 3, characterized in that, The outer side of the push plate (4) has an annular protrusion (43) surrounding the perforation (41). The inner peripheral wall of the annular protrusion (43) is in contact with the outer peripheral wall of the T-shaped column (31), and the push plate (4) abuts against the inner bottom wall of the outer cover (2) through the annular protrusion (43).

5. The sealing cap for a silent drain pipe according to any one of claims 1-4, characterized in that, The maintenance channel (11) has a retaining edge (12) at the inner end port. The retaining edge (12) is arranged circumferentially along the inner end port of the maintenance channel (11). A first step groove (34) is opened at the outer edge of the inner end face of the piston (3). The retaining edge (12) is embedded in the first step groove (34).

6. The sealing cap for a silent drain pipe according to claim 5, characterized in that, The maintenance channel (11) has a second step groove (13) near the middle. The second step groove (13) is opened circumferentially along the inner wall of the maintenance channel (11). The outer end of the piston (3) protrudes radially outward and is embedded in the second step groove (13).

7. The sealing cap for a silent drain pipe according to claim 6, characterized in that, The inner wall of the maintenance channel (11) has a number of retaining ribs (14), each of the retaining ribs (14) is arranged along the axial direction of the maintenance channel (11), and the number of retaining ribs (14) is arranged at intervals along the circumference of the maintenance channel (11). The outer wall of the piston (3) is provided with a number of guide grooves (35) along the axial direction of the maintenance channel (11), and each of the retaining ribs (14) and each of the guide grooves (35) are positioned opposite each other and embedded therein.

8. The sealing cap for a silent drain pipe according to claim 7, characterized in that, One end of each of the retaining ribs (14) is connected to the retaining edge (12) as a whole, and the other end is flush with the bottom wall of the second step groove (13).

9. The sealing cap for a silent drain pipe according to claim 8, characterized in that, An installation groove (36) is provided on the outer side wall of the outer end of the piston (3). The installation groove (36) is opened along the circumference of the piston (3). A sealing ring (361) is embedded in the installation groove (36) and abuts against the side wall of the second step groove (13).

10. The sealing cap for a silent drain pipe according to claim 3 or 4, characterized in that, The outer end face of the outer cover (2) has an annular rib one (22) and an annular rib two (23). The annular rib one (22) is located at the outer edge of the end face of the outer cover (2), and the annular rib two (23) is located inside the annular rib one (22). The two are concentrically arranged around the perforation two (21). The annular rib two (23) is provided with a number of long strip reinforcing ribs (24). The number of reinforcing ribs (24) are arranged circumferentially along the annular rib two (23). One end of each reinforcing rib (24) is connected to the annular rib one (22), and the other end extends to the edge of the perforation two (21).

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