Liquid pipe counter locking connector

Abstract

The liquid pipe counter locking connector comprises a connector body and a locking nut, external pipes are arranged on the two sides of the connector body, threads are arranged on the outer circumferences of the external pipes, and the external pipes are in threaded connection with the locking nut. An elastic locking ring is arranged at the end of the outer connecting pipe and forms a plurality of claw petals capable of being opened and closed in the radial direction through elastic straight grooves and elastic curved grooves. A screw hole is formed in the locking nut, and a locking step in the screw hole can radially compress the elastic locking ring, so that an inner ring of the elastic locking ring and the inner connecting pipe form a telescopic space, and counter locking and fastening of the liquid pipe are achieved. The connecting structure has the advantages of being compact in structure, good in sealing performance and pulling-out resistance and capable of improving the stability and safety of pipeline connection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fluid pipe connection, in particular to a liquid pipe reverse locking connector. BACKGROUND

[0002] In fluid conveying systems, liquid pipe connection devices are widely used in various industrial, agricultural and civilian pipeline systems, such as hydraulic systems, pneumatic systems and oil and gas pipelines. The traditional pipe connection methods mainly include threaded connection, clamp connection, welding and quick plug-in connection. Among them, although the threaded connection and welding method has high sealing and stability, the installation and disassembly are relatively cumbersome, and the welding method is not suitable for application scenarios that need to be frequently disassembled. Although the quick plug-in connection is convenient to install, it is easy to loosen in high pressure or vibration environment, resulting in leakage or falling off.

[0003] In order to solve the above problems, part of the liquid pipe connector adopts the combination of locking nut and sealing ring, and the sealing ring is deformed under pressure by the tightening action of the nut, so as to enhance the sealing effect. However, the existing locking structure still has the following disadvantages: on the one hand, the fixing method of the traditional sealing ring is relatively single, and it is difficult to balance the sealing performance and anti-falling performance; on the other hand, part of the locking mechanism may cause the sealing ring to deform and fail when subjected to large external force or pressure impact, reducing the reliability of the liquid pipe connection. CONTENT OF THE INVENTION

[0004] In order to improve the anti-pulling-off ability of the liquid pipe, the present application provides a liquid pipe reverse locking connector.

[0005] The liquid pipe reverse locking connector provided by the present application adopts the following technical scheme:

[0006] A liquid pipe reverse locking connector, comprising a connector body, the connector body comprising a connector main body and a locking nut;

[0007] Both sides of the connector main body are provided with an external pipe, and the outer circumference of the external pipe is provided with threads, and the locking nut is screwed with the threads of the external pipe;

[0008] The outer end of the external pipe is provided with an elastic locking ring, a group of elastic straight grooves and a plurality of groups of elastic curved grooves are symmetrically arranged around the elastic locking ring, and the elastic straight grooves and the elastic curved grooves divide the elastic locking ring into a plurality of claw petals that can be radially opened and closed;

[0009] The locking nut is provided with a screw hole, one end of the screw hole is provided with an inner step, the other end of the screw hole is provided with a locking step, the inner diameter of the inner step is smaller than the maximum outer diameter a of the elastic locking ring, the inner diameter of the inner step is consistent with the bottom diameter of the screw hole, and the inner diameter a1 of the locking step is consistent with the top diameter of the screw hole;

[0010] When the locking nut is axially sleeved into the joint body, the inner step, the screw hole and the locking step radially elastically reduce the claw petals of the elastic locking ring, and the locking nut is axially sleeved into the joint body and screwed.

[0011] By adopting the technical scheme, the elastic locking ring and the locking nut are combined to realize efficient locking and anti-disengagement of the liquid pipe connection. The end of the external pipe is provided with the elastic locking ring which is divided into claw petals capable of being radially opened and closed by the elastic straight groove and the elastic curved groove. The elastic locking ring has good elastic adjustment capability when being locked or unlocked. The locking nut is internally provided with the screw hole. When the locking nut is screwed, the locking step pushes the claw petals of the elastic locking ring to radially contract inward, so as to tightly hold the connecting pipe and realize strong locking. When the nut is unscrewed, the locking step releases the radial compression, and the claw petals return to the original position, facilitating disassembly. The structure not only improves the sealing and anti-disengagement capability of the connection, but also effectively avoids the problem that the traditional quick plug joint is easily loosened in a high-pressure or vibration environment.

[0012] Optionally, the joint body is provided with an internal connecting pipe at both ends, and a through hole is arranged at the central position of the joint body, the through hole penetrating the internal connecting pipe and the middle part of the joint body.

[0013] By adopting the technical scheme, the coaxiality of the pipe connection is ensured, the fluid resistance is reduced, the conveying efficiency is improved, the internal flow channel is smoother due to the penetrating design of the through hole, the working stability of the system is improved, the mechanical strength of the joint as a whole is strengthened, the pressure resistance is improved, and the liquid conveying environment with high flow or high pressure is applicable.

[0014] Optionally, the outer circumference of the elastic locking ring is composed of a curved surface and a chamfer, the small end of the curved surface is connected to the end face of the external connecting pipe, the outer diameter of the large end of the curved surface is a, the large end of the curved surface is the large end of the chamfer, and the small end of the chamfer is contracted and stretched outward.

[0015] By adopting the technical scheme, the outer circumference of the elastic locking ring is composed of a curved surface and a chamfer, the curved surface optimizes the stress distribution, the elastic locking ring is subjected to more uniform stress when being radially scaled, the local stress concentration is reduced, the durability is improved, the elastic locking ring can smoothly transition during the screwing of the nut due to the chamfer, the installation resistance is effectively reduced, and the assembly convenience is improved.

[0016] Optionally, a bending groove is arranged at one side of the outer end of the elastic curved groove, the large end of the elastic curved groove is connected to the end face of the external connecting pipe, the curved surface of the elastic curved groove is contracted inward at the other end and connected to the bending groove, and the other end of the bending groove is reversely stretched outward.

[0017] By adopting the above technical scheme, the bending groove is arranged on one side of the outer end of the elastic curved groove, so that the claw petals of the locking ring have excellent elastic deformation capability when being radially opened and closed, the bending groove enhances the flexibility of the claw petals, so that the claw petals can be more smoothly contracted and restored in the stress process, the fatigue resistance and service life of the locking ring are improved, in addition, the reverse extension structure of the bending groove helps to buffer the stress impact, reduces the resistance during installation, and ensures smooth transition of the claw petals between the locked and unlocked states, thereby improving the stability and sealing performance of the liquid pipe joint.

[0018] Optionally, the inner ring of the elastic locking ring and the inner connecting pipe form an expansion space b, which is a blind hole.

[0019] By adopting the above technical scheme, the inner ring of the elastic locking ring and the inner connecting pipe form an expansion space b, so that the joint can realize radial contraction and restoration of the elastic claw petals during locking, thereby enhancing the stability and sealing performance of the connection, the expansion space b enables the elastic locking ring to adapt to different pipe connection requirements, ensures that the liquid pipe can still be firmly locked in a high-pressure or vibration environment, avoids liquid leakage or loosening problems, and improves the reliability and service life of the connecting piece.

[0020] Optionally, the claw petal inner ring wall of the elastic locking ring is provided with protruding locking buckles.

[0021] By adopting the above technical scheme, the claw petal inner ring wall of the elastic locking ring is provided with protruding locking buckles, which effectively increase the locking strength with the inner connecting pipe and enhance the fixing force of the connecting component, when the locking nut is rotated, the locking buckles of the claw petal inner ring wall tightly cooperate with the inner connecting pipe wall, ensuring firm connection of the liquid pipe and preventing loosening or leakage.

[0022] Optionally, the middle end of the joint body is provided with a plurality of outwardly protruding annular rings in parallel on the outer circumference, and the diameters of the annular rings are smaller than the diameters of the steps on both sides of the middle end.

[0023] By adopting the above technical scheme, the middle end of the joint body is provided with a plurality of outwardly protruding annular rings in parallel on the outer circumference, and the diameters of the annular rings are smaller than the diameters of the steps on both sides of the middle end, which effectively enhances the mechanical strength and stability of the joint, the outwardly protruding annular rings can provide additional support and anti-skid effect when connected with other components, ensuring that the joint is not easily deformed or loosened under pressure or tension, thereby improving the reliability of the connection, reducing the risk of leakage, and ensuring the safety and long-term stable operation of the liquid pipe system.

[0024] Optionally, the locking nut is screwed inwardly, the locking nut abuts against the step end face, the plurality of radially openable claw petals of the elastic locking ring are in an elastic restoration state, and the size of the expansion space b is also in the restoration state.

[0025] The locking nut is screwed outwards, and the end face of the locking nut is away from the step, the locking step axially presses the radially expanded slope of the elastic locking ring, the locking step radially compresses each claw lobe of the elastic locking ring to be radially elastically reduced, the inner ring of the elastic locking ring and the inner connecting pipe form a telescopic space b to be synchronously reduced, and the locking buckle protruding from the inner ring of each claw lobe is synchronously reduced in the spacing with the outer circumferential wall of the inner connecting pipe.

[0026] By adopting the above technical scheme, when the locking nut is screwed inwards, the end face of the locking nut is abutted against the step end face, the claw lobe of the elastic locking ring is in an elastic recovery state, and the size of the telescopic space b is also in a recovery state, so that the joint can maintain stable structure and sealing when not locked. When the locking nut is screwed outwards, the end face of the locking nut is away from the step, the locking step axially presses the radially expanded slope of the elastic locking ring, the locking step radially compresses the claw lobe of the elastic locking ring, the claw lobe is radially reduced inwardly, thereby enhancing the locking effect of the liquid pipe. In this process, the inner ring of the elastic locking ring and the inner connecting pipe form a telescopic space b to be synchronously reduced, and the locking buckle protruding from the inner ring of the claw lobe is synchronously reduced in the spacing with the outer circumferential wall of the inner connecting pipe, thereby effectively improving the fixing force and sealing of the liquid pipe, preventing loosening and leakage, and ensuring the reliability, stability and safety of the liquid conveying system. This design can adaptively change under different use conditions, and provide a lasting locking effect.

[0027] In summary, the present application has at least one of the following beneficial technical effects:

[0028] The present application can realize quick and reliable pipeline connection by arranging the combination structure of the elastic locking ring and the locking nut in the liquid pipe counter-lock joint. When the locking nut is screwed into the joint body, the inner step, the screw hole and the locking step jointly act to make the claw lobe of the elastic locking ring radially elastically reduced, firmly fix the pipeline connecting component, and prevent loosening and leakage. This structure improves the sealing and stability of the connection, simplifies the operation, has good anti-vibration and durability, and is suitable for liquid conveying systems requiring high safety and reliability.

[0029] The inner connecting pipe and the through hole at both ends of the joint body effectively enhance the structural stability of the joint, ensure that the liquid pipe connection is not prone to loosening or leakage, and improve the safety and reliability of the liquid conveying system.

[0030] The outer circumference of the elastic locking ring is composed of a curved surface and a chamfer, which can provide more stable pressure distribution during connection, effectively avoid local excessive compression, and improve the sealing effect and service life.

[0031] The cooperation of the elastic curved groove and the bending groove can enhance the adaptability of the locking ring, improve the radial opening and closing ability of the claw lobe, and ensure that the joint can maintain good sealing effect and stable connection state under different working environments.

[0032] The blind hole-shaped expansion space formed by the elastic locking ring and the inner connecting pipe makes the locking ring have greater adaptive space during the working process, which helps to maintain the sealing and flexibility of the system and avoid connection failure caused by excessive pressure;

[0033] The claw inner ring is provided with a protruding locking buckle, which can effectively prevent the joint from slipping when subjected to external force, further improving the safety and durability of the joint. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a schematic diagram of a liquid pipe reverse locking joint according to an embodiment of the present application.

[0035] Figure 2 is a right view of Figure 1 .

[0036] Figure 3 is a schematic diagram of a joint body in Figure 1 .

[0037] Figure 4 is a schematic diagram of a locking nut in Figure 1 .

[0038] Figure 5 is an axial sectional view of Figure 3 .

[0039] Figure 6 is a state diagram in the reverse locking state. Figure 1

[0040] BRIEF DESCRIPTION OF DRAWINGS: 100, joint body; 10, joint body; 101, elastic curved groove; 1010, bent groove; 102, inner connecting pipe; 1021, locking buckle; 1022, through hole; 103, elastic straight groove; 104, intermediate end; 1040, circular ring; 107, elastic locking ring; 106, outer connecting pipe; 105, step; 20, locking nut; 201, locking step; 202, inner step; 203, screw hole. DETAILED DESCRIPTION

[0041] The present application will be further described below in conjunction with the accompanying drawings. Figures 1-6 The present application will be further described below in conjunction with the accompanying drawings.

[0042] The present application discloses a liquid pipe reverse locking joint. Referring to Figure 1 ​The joint body 100 is integrally formed by an elastic thermoplastic material, including but not limited to TPEE, nylon, etc. The joint body 100 includes a joint main body 10 and a locking nut 20. The locking nut 20 is two pieces, and the two pieces of the locking nut 20 are respectively threadedly connected with the joint main body 10. The joint main body 10 is internally provided with an inner connector pipe 102 at both ends, and a through hole 1022 is arranged at the center position of the joint main body 10. The through hole 1022 penetrates the inner connector pipe 102 and the middle part of the joint main body 10. When the joint is applied, the inner connector pipe 102 at both ends of the joint main body 10 is sleeved with a liquid pipe. After the locking nut 20 is rotated, the locking nut 20 is axially displaced outward. The outer end of the axially displaced locking nut 20 synchronously tightens the claw petals of the outer connector pipe 106 on both sides of the joint main body 10 radially inward. The locking catch 1021 protruding on the inner ring wall of the claw petals axially locks the liquid pipe sleeved on the inner connector pipe 102, thereby realizing good anti-disengagement effect of the liquid pipe and the inner connector pipe 102.

[0043] Referring to Figure 3 The joint main body 10 is internally provided with an outer connector pipe 106 at both sides. The outer circumference of the outer connector pipe 106 is provided with threads, and the locking nut 20 is threadedly connected with the threads of the outer connector pipe 106. The outer end of the outer connector pipe 106 is provided with an elastic locking ring 107. The elastic locking ring 107 is symmetrically provided with a group of elastic straight grooves 103 and a plurality of groups of elastic curved grooves 101 in the circumferential direction. The elastic straight grooves 103 and the elastic curved grooves 101 divide the elastic locking ring 107 into a plurality of claw petals that can be radially expanded and contracted. When an inward external force is applied to the outer circumference of the elastic locking ring 107, the claw petals that can be radially expanded and contracted can be elastically reduced radially inward, and the circumferential diameter formed at the inner end of each claw petal is synchronously reduced.

[0044] Referring to Figure 3 , Figure 4 The locking nut 20 is internally provided with a threaded hole 203. One end of the threaded hole 203 is provided with an inner step 202, and the other end of the threaded hole 203 is provided with a locking step 201. The inner diameter of the inner step 202 is smaller than the maximum outer diameter a of the elastic locking ring 107. The inner diameter of the inner step 202 is consistent with the bottom diameter of the threaded hole 203. The inner diameter a1 of the locking step 201 is consistent with the top diameter of the threaded hole 203. When the locking nut 20 is axially sleeved into the joint main body 10, the diameter a1 of the locking step 201 axially closes and elastically pushes the maximum outer diameter a of the elastic locking ring 107 to contract inward. The claw petals of the elastic locking ring 107 are synchronously elastically closed and contracted radially inward, and the locking nut 20 is axially entered into the joint main body 10 and is threadedly connected.

[0045] Referring to Figure 5 , Figure 6, the locking nut 20 is screwed inward, the locking nut 20 abuts against the end face of the step 105, the claws of the elastic locking ring 107 are in the elastic recovery state, and the size of the expansion space b is also in the recovery state; the locking nut 20 is screwed outward, the end face of the locking nut 20 is away from the step 105, the locking step 201 abuts against the radial expansion slope of the elastic locking ring 107 in the axial direction, the locking step 201 compresses each claw of the elastic locking ring 107 in the radial direction to elastically reduce the radial direction, the inner circle of the elastic locking ring 107 and the inner connecting pipe 102 form the expansion space b to be reduced synchronously, the spacing between the locking buckle 1021 protruding from the inner circle of each claw and the outer circumferential wall of the inner connecting pipe 102 is reduced synchronously, the protruding locking buckle 1021 is firmly and detachably connected to the outer circumferential wall of the liquid pipe connected by the inner connecting pipe 102, and good liquid pipe anti-disconnection function is realized.

[0046] Referring to Figure 3 , the outer circumference of the elastic locking ring 107 is composed of a curved surface and a chamfer, the small end of the curved surface is connected to the end face of the outer connecting pipe 106, the outer diameter of the large end of the curved surface is a, the large end of the curved surface is the large end of the chamfer, the small end of the chamfer is contracted and stretched outward, the outer end of the elastic curved groove 101 is provided with a bending groove 1010, the large end of the elastic curved groove 101 is connected to the end face of the outer connecting pipe 106, the other end of the curved surface of the elastic curved groove 101 is contracted inward and connected to the bending groove 1010, the other end of the bending groove 1010 is reversely stretched outward, the elastic locking ring 107 is combined by the curved surface and the chamfer, which can effectively adapt to different installation spaces and use environments while ensuring the connection strength, the design of the curved surface makes the contact surface of the outer circumference smoother, which can reduce wear and loosening caused by loose connection or external impact, and the stability of the connection is enhanced, at the same time, the small end of the curved surface is connected to the end face of the outer connecting pipe 106, which is helpful to realize better sealing effect, the chamfer is contracted and stretched, the small end of the chamfer is stretched and contracted outward, which makes the locking ring have better elasticity and adaptability, and the elastic locking ring can maintain good stability when subjected to pressure or vibration, the structure of the elastic curved groove 101 makes the elastic locking ring have stronger elasticity and pressure resistance, and the bending groove 1010 at the outer end can further enhance the locking effect and avoid loosening caused by external impact, and the reverse stretching design of the bending groove enhances the restoring force and elasticity of the elastic locking ring to some extent, so that the locking effect is more durable.

[0047] Referring to Figure 5 , the inner circle of the elastic locking ring 107 and the inner connecting pipe 102 form an expansion space b, the expansion space b is blind hole-shaped, the overall strength of the inner connecting pipe 102 is improved, and the expansion space b is also a space release space and a closed space for the claws to radially stretch inward.

[0048] Referring to Figure 1 , Figure 3 , Figure 5 , Figure 6The middle end 104 is provided with a plurality of outward convex annular rings 1040, and the diameters of the annular rings 1040 are smaller than the diameters of the steps 105 on both sides of the middle end 104. The plurality of annular rings 1040 not only save the raw materials of the joint body 10, but also improve the absorption and buffering of the thermal deformation and low-temperature deformation of the middle end 104.

[0049] The implementation principle of the liquid pipe reverse locking joint is as follows: the liquid pipe reverse locking joint realizes stable connection and anti-falling function of the liquid pipe through a series of reverse locking structures. The joint body 100 is integrally formed by an elastic thermoplastic material (such as TPEE or nylon), has excellent elasticity and chemical corrosion resistance, and includes a joint body 10 and two locking nuts 20. The two ends of the joint body 10 are provided with inner connecting pipes 102, and the liquid pipe is sleeved through the inner connecting pipes. The locking nut 20 is axially moved by rotating, and then drives the claws of the outer connecting pipe 106 to be radially tightened, so as to tightly lock the liquid pipe on the inner connecting pipe 102, ensure the close connection between the liquid pipe and the joint, and prevent falling. The outer circumference of the elastic locking ring 107 is a combination of a curved surface and a chamfer. The outer circumference is divided into an elastic straight groove 103 and an elastic curved groove 101. The locking ring is divided into a plurality of claws that can be radially opened and closed through the grooves. When the locking nut 20 is screwed into the joint body, the locking step 201 pushes the elastic locking ring 107 to shrink inward, forcing the claws to be radially tightened, thereby enhancing the fixing force of the liquid pipe and the joint. The bending groove 1010 in the elastic curved groove 101 further enhances the locking effect. The bending groove can enhance the restoring force of the elastic locking ring under external force, ensure that the claws can quickly recover to the original state, thereby avoiding loosening caused by external pressure or vibration. The locking buckle 1021 at the inner end of the claw is tightly matched with the outer circumferential wall of the inner connecting pipe 102, so as to ensure the stable connection of the liquid pipe and further improve the anti-falling function. The middle end 104 of the joint body 10 has an outward convex annular ring 1040, which enhances the overall structural strength of the joint. The whole structure ensures the firm combination of the liquid pipe and the joint, and can maintain stable connection in a high-pressure or vibration environment, thereby achieving good anti-falling and sealing effect.

[0050] The above are preferred embodiments of the present application, but do not limit the protection scope of the present application. Therefore, any equivalent changes made on the basis of the structure, shape and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A liquid pipe counter lock joint comprising a joint body (100), characterized in that: The joint body (100) comprises a joint main body (10) and a locking nut (20); Both sides of the joint main body (10) are provided with an outer connecting pipe (106), the outer circumference of the outer connecting pipe (106) is provided with threads, and the locking nut (20) is screwed with the threads of the outer connecting pipe (106); The outer end of the outer connecting pipe (106) is provided with an elastic locking ring (107), a plurality of groups of elastic curved grooves (101) and a group of elastic straight grooves (103) are symmetrically arranged on the outer circumference of the elastic locking ring (107), the elastic straight grooves (103) and the elastic curved grooves (101) divide the elastic locking ring (107) into a plurality of claw petals that can be radially expanded and contracted; The locking nut (20) is provided with a threaded hole (203) inside, one end of the threaded hole (203) is provided with an inner step (202), the other end of the threaded hole (203) is provided with a locking step (201), the inner diameter of the inner step (202) is smaller than the maximum outer diameter a of the elastic locking ring (107), the inner diameter of the inner step (202) is consistent with the bottom diameter of the threaded hole (203), and the inner diameter a1 of the locking step (201) is consistent with the top diameter of the threaded hole (203); When the locking nut (20) is axially sleeved into the joint main body (10), the inner step (202), the threaded hole (203) and the locking step (201) radially and elastically reduce the claw petals of the elastic locking ring (107) inward, and the locking nut (20) is axially inserted into the joint main body (10) and screwed.

2. A liquid pipe counter lock connector according to claim 1, characterized in that: Both ends of the joint main body (10) are provided with an inner connecting pipe (102), and the center position of the joint main body (10) is provided with a through hole (1022) penetrating the middle part of the inner connecting pipe (102) and the joint main body (10).

3. A liquid pipe counter lock connector according to claim 1, wherein: The outer circumference of the elastic locking ring (107) is composed of a curved surface and a chamfer, the small end of the curved surface is connected to the end face of the outer connecting pipe (106), the outer diameter of the large end of the curved surface is a, the large end of the curved surface is the large end of the chamfer, and the small end of the chamfer is contracted and stretched outward.

4. A liquid pipe counter lock connector according to claim 1, wherein: The outer end of the elastic curved groove (101) is provided with a bending groove (1010), the large end of the elastic curved groove (101) is connected to the end face of the outer connecting pipe (106), the other end of the curved surface of the elastic curved groove (101) is contracted inward and connected to the bending groove (1010), and the other end of the bending groove (1010) is reversely stretched outward.

5. A liquid tube counter lock connector according to claim 1, wherein: The inner ring of the elastic locking ring (107) and the inner connecting pipe (102) form an expansion space b, and the expansion space b is a blind hole.

6. A liquid pipe counter lock connector according to claim 5, wherein: The claw petal inner ring wall of the elastic locking ring (107) is provided with a protruding locking buckle (1021).

7. A liquid tube counter lock connector according to claim 5, wherein: The middle part of the joint main body (10) is provided with a middle end (104), and a plurality of outer convex annular rings (1040) are arranged in parallel on the outer circumference of the middle end (104), the diameters of the annular rings (1040) are smaller than the diameters of the steps (105) on both sides of the middle end (104).

8. A liquid tube counter lock connector according to claim 7, wherein: The locking nut (20) is screwed inward, the locking nut (20) abuts against the end face of the step (105), the claws of the elastic locking ring (107) are in the elastic recovery state, and the size of the expansion space b is also in the recovery state. The locking nut (20) is screwed outward, the end face of the locking nut (20) is away from the step (105), the locking step (201) abuts against the radially expanded inclined surface of the elastic locking ring (107) in the axial direction, the locking step (201) compresses each claw of the elastic locking ring (107) in the radial direction to elastically reduce the claw inward in the radial direction, the inner ring of the elastic locking ring (107) and the inner connecting pipe (102) form the expansion space b which is synchronously reduced, and the locking buckle (1021) protruding from each claw is synchronously reduced with the distance between the outer circumferential wall of the inner connecting pipe (102).

Images