A pipe connection structure

Abstract

The present invention discloses a pipeline connection structure, including a valve body connecting pipe, a connecting pipe and a nut; the connecting pipe is made of aluminum and also includes an isolation sleeve, a sealing ring, a gasket and a bushing, the gasket and the bushing are located in the inner cavity of the nut, the sealing ring and the gasket are fixedly connected or form an integral structure, the bushing is sleeved on the outer periphery of the sealing ring, and the nut and the bushing are made of copper; the end of the connecting pipe forms a flared section, the isolation sleeve is sleeved on the connecting pipe, the nut and the bushing are sleeved on the isolation sleeve, a first conical surface matching pair is provided between the flared section and the isolation sleeve, and a second conical surface matching pair is provided between the isolation sleeve and the bushing; one end of the sealing ring abuts against the valve body connecting pipe to form a first sealing structure, and the other end abuts against the flared section to form a second sealing structure. This connection structure reduces the design requirements for the taper of the relevant conical surface, applies a smaller tightening torque to ensure the sealing effect, is easy to operate, and can use an aluminum connecting pipe at a lower cost.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration control, and in particular to a pipeline connection structure. Background Art

[0002] A globe valve comprises a valve body and a valve stem. A first port is defined on the side of the valve body, and a second port is defined on the bottom. The two ports are connected via a valve orifice. The valve stem is located within the inner cavity of the valve body and is connected to the valve body via a threaded pair. When the valve stem is rotated, the threaded pair allows it to move up and down along the inner cavity of the valve body, closing or opening the valve orifice, thereby blocking or opening the passage between the first and second ports.

[0003] The movable connection structure between the stop valve and the pipeline usually includes a connecting pipe end of the stop valve body, a connecting pipe and a nut; the end face of the connecting pipe end of the valve body forms an outer conical surface, and the end of the connecting pipe that cooperates with the connecting pipe end is provided with a trumpet-shaped flared section to form a conical surface that cooperates with the outer conical surface of the connecting pipe end; the nut is outermostly fitted on the connecting pipe, and the nut has an inner conical surface, and the connecting pipe end also has a thread that cooperates with the nut; during installation, the nut is connected to the connecting pipe end of the valve body through a thread, and by tightening the nut, the inner conical surface of the nut presses the flared section of the connecting pipe against the outer conical surface of the connecting pipe end, so that the flared section of the connecting pipe and the outer conical surface of the connecting pipe end form a conical surface seal.

[0004] The base material of the valve body and nut in this structure is usually brass. When using low-cost aluminum connecting pipes, there is a potential difference at the copper-aluminum connection, which is prone to electrical corrosion in a relatively humid environment or when water intrudes. Summary of the Invention

[0005] The object of the present invention is to provide a pipeline connection structure that can use an aluminum connecting pipe while ensuring sealing reliability.

[0006] To solve the above technical problems, the present invention provides a pipeline connection structure, comprising a valve body connecting portion, a connecting pipe, and a nut; the connecting pipe is made of aluminum, and the valve body connecting portion and the nut have a thread pair that cooperates with each other; the structure also includes a spacer sleeve, a sealing ring, a gasket, and a bushing, wherein the sealing ring, the gasket, and the bushing are located in the inner cavity of the nut, the sealing ring and the gasket are fixedly connected or form an integral structure, the bushing is sleeved on the outer periphery of the sealing ring, and the nut and the bushing are made of copper;

[0007] The end of the connecting pipe is formed with a flared section, the isolation sleeve is externally mounted on the connecting pipe, the nut and the bushing are externally mounted on the isolation sleeve, a first tapered surface fitting pair is formed between the flared section and the isolation sleeve, and a second tapered surface fitting pair is formed between the isolation sleeve and the bushing;

[0008] One end of the sealing ring abuts against the connecting portion of the valve body to form a first sealing structure, and the other end abuts against the flared section to form a second sealing structure.

[0009] The present invention provides a pipeline connection structure. Through the optimized design of the pipeline connection structure, it includes an isolation sleeve, a sealing ring, a gasket and a bushing. The sealing ring and the gasket are fixedly connected or are an integrated structure. The bushing is arranged on the outer periphery of the sealing ring. The connecting pipe is made of aluminum, and the nut and the bushing are made of copper. One end of the sealing ring is against the connecting pipe part of the valve body to form a first sealing structure, and the other end is against the flared section to form a second sealing structure. The pipeline connection structure can use an aluminum connecting pipe while ensuring sealing reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A schematic cross-sectional view of a specific embodiment of the connection structure between the stop valve and the pipeline provided by the present invention;

[0011] Figure 2 for Figure 1 A partial enlarged view of part A in the middle;

[0012] Figure 3 for Figure 1 Schematic diagram of the structure of the connecting pipe;

[0013] Figure 4 for Figure 2 Schematic diagram of the structure of the middle nut;

[0014] Figure 5 for Figure 4 A schematic cross-sectional view of the nut shown;

[0015] Figure 6 for Figure 2 Schematic diagram of the structure of the middle sealing ring;

[0016] Figure 7 for Figure 6 A schematic cross-sectional view of the sealing ring shown;

[0017] Figure 8 for Figure 2 Schematic diagram of the structure of the middle washer;

[0018] Figure 9 for Figure 8 A schematic cross-sectional view of the gasket shown;

[0019] Figure 10 for Figure 2 Schematic diagram of the structure of the middle bushing;

[0020] Figure 11 for Figure 10 A schematic cross-sectional view of the bushing shown;

[0021] Figure 12for Figure 2 Schematic diagram of the structure of the plastic isolation sleeve;

[0022] Figure 13 for Figure 12 A front view of the plastic isolation sleeve shown;

[0023] Figure 14 This is a cross-sectional schematic diagram of another specific embodiment of the connection structure between the stop valve and the pipeline provided by the present invention.

[0024] Description of reference numerals:

[0025] Valve body 110, valve mouth 111, valve body connecting pipe 112, outer conical surface 1121, lower connecting pipe 113, valve stem 120, valve cap 130;

[0026] Connecting pipe 200, flared section 210, first outer conical surface 211;

[0027] Nut 300, first inner conical surface 310;

[0028] Sealing ring 400, large diameter portion 410, small diameter portion 420;

[0029] Washer 500, inner conical surface 510;

[0030] Bushing 600, tapered portion 610, second outer tapered surface 611, circular sleeve portion 620, first circular hole 630, tapered hole 640, second circular hole 640;

[0031] Plastic isolation sleeve 700, cylindrical portion 710, tapered cylindrical portion 720, third outer cone surface 721, second inner cone surface 722;

[0032] Thread pair S1;

[0033] The first conical surface matching pair V1, the second conical surface matching pair V2, and the third conical surface matching pair V3;

[0034] First sealing structure M1, M1', second sealing structure M2. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0036] Without loss of generality, this article takes the application of the pipeline connection structure in the connection between the stop valve and the pipeline as an example. Other similar application scenarios are similar and will not be described in detail.

[0037] Please refer to Figure 1 and Figure 2 , Figure 1A schematic cross-sectional view of a specific embodiment of the connection structure between the stop valve and the pipeline provided by the present invention; Figure 2 for Figure 1 A partial enlarged view of area A in the middle.

[0038] The stop valve includes a valve body 110, a valve stem 120 and a valve bonnet 130; wherein, a valve body connecting pipe portion 112 with a flow channel is formed on the side of the valve body 110, and the lower portion of the valve body 110 has a connecting portion connected to the lower connecting pipe 113, and a valve mouth portion 111 is also formed in the valve body 110; the valve stem 120 is inserted into the valve cavity from the upper opening of the valve body 110 through its threaded portion, and by rotating the valve stem 120 to move it up and down along the inner cavity of the valve body 110, the valve mouth portion 111 can be closed or opened, so that the channel formed between the valve body connecting pipe portion 112 and the lower connecting pipe 113 is cut off or connected.

[0039] The upper opening of the valve body 110 is sealed by the valve cap 130 .

[0040] In actual application, the lower connecting pipe 113 of the stop valve is usually welded to the valve body 110, and the valve body connecting pipe part 112 is connected to other pipelines through a movable connection structure, such as in the air conditioning pipeline, which is convenient for installation with the indoor unit.

[0041] The focus of the present invention is on the connection structure between the valve body connecting pipe portion 112 of the stop valve and the pipeline, which will be described in detail below.

[0042] The valve body connecting pipe 112, the connecting pipe 200 and the nut 300, wherein the nut 300 has an internal threaded portion, the valve body connecting pipe 112 has an external threaded portion threadedly matched with the internal threaded portion, and the nut 300 and the valve body connecting pipe 112 are threadedly connected through a thread pair S1 formed by the internal threaded portion and the external threaded portion.

[0043] The valve body 110 and the nut 300 are both made of copper.

[0044] The connection structure further includes a sealing ring 400 , a washer 500 , a bushing 600 and an isolation sleeve, wherein the washer 500 and the bushing 600 are both sleeved inside the nut 300 , and the bushing 600 and the washer 500 are also made of copper material.

[0045] In this embodiment, the isolation sleeve is made of plastic material, namely, a plastic isolation sleeve 700. It is understandable that in other solutions, the isolation sleeve may also be made of other suitable materials.

[0046] The sealing ring 400 includes a large diameter portion 410 and a small diameter portion 420 connected to the large diameter portion 410, that is, the sealing ring 400 is a stepped columnar structure, the small diameter portion 420 of the sealing ring 400 is inserted into the washer 500, and the large diameter portion 410 is inserted into the bushing 600. It can be understood that the sealing ring 400 is built into the inner cavity of the nut 300.

[0047] A flared section 210 is formed at the end of the connecting pipe 200. The flared section 210 has a conical structure and has a first outer conical surface 211. The end of the connecting pipe 200 is provided with the flared section 210, which is inserted into the nut 300 and the bushing 600. The aforementioned plastic isolation sleeve 700 is located between the connecting pipe 200 and the nut 300 and the bushing 600, that is, the nut 300 and the bushing 600 are outermostly on the plastic isolation sleeve 700, and the plastic isolation sleeve 700 is outermostly on the connecting pipe 200; and a first conical surface fitting pair V1 is formed between the flared section 210 and the plastic isolation sleeve 700, a second conical surface fitting pair V2 is formed between the plastic isolation sleeve 700 and the bushing 600, and a third conical surface fitting pair V3 is formed between the bushing 600 and the nut 300.

[0048] It should be noted here that the above-mentioned conical surface mating pair refers to two components having two matching conical surfaces respectively. When a torque is applied to one component, the conical surface of the component can be pressed against the conical surface of the other component to transmit the torque. The conical surface mating pair involved in this article is not limited to the situation where the two conical surfaces are completely fitted.

[0049] When the nut 300 is threadedly connected to the valve body connecting pipe 112 through the thread pair S1, a first sealing structure M1 is formed between the valve body connecting pipe 112 and the small diameter portion 420 of the sealing ring 400, and a second sealing structure M2 is formed between the flared section 210 of the connecting pipe 200 and the large diameter portion 410 of the sealing ring 400.

[0050] As described above, the connection structure provided by the present invention, during the process of tightening the nut 300, through the compression fit of the first conical surface fitting pair V1, the second conical surface fitting pair V2, and the third conical surface fitting pair V3, the small diameter portion 420 of the sealing ring 400 is compressed and sealed with the valve body connecting portion 112, and the flared section 210 of the connecting pipe 200 is compressed and sealed with the large diameter portion 410 of the sealing ring 400. In this way, the connection structure forms two seals through the arrangement of the relevant structures, and both sealing structures are non-conical surface sealing structures. Compared with the prior art, the precision requirements for the conical surface fitting pairs are reduced, which can reduce processing costs. At the same time, the sealing requirements can be achieved by applying a relatively small tightening torque, which is more convenient to operate and has a better sealing effect. Due to the small tightening torque applied, the thread of the valve body connecting portion 112 can be prevented from being damaged or rotten.

[0051] In addition, due to the provision of the plastic isolation sleeve 700, the connecting pipe 200 can be made of aluminum, which can avoid electrical corrosion caused by the potential difference between the connecting pipe 200 and the nut 300 and the bushing 600, thereby ensuring the reliability of the product.

[0052] In the illustrated example, the sealing ring 400 is a stepped columnar structure. It can be understood that in other embodiments, the sealing ring 400 can also be of other structures and is not limited to the illustration. Regardless of the specific structure of the sealing ring 400, one end thereof can be abutted against the valve body connecting pipe portion 112 to form a first sealing structure, and the other end thereof can be abutted against the flared section 210 of the connecting pipe 200 to form a second sealing structure.

[0053] In the illustrated example, the sealing ring 400 and the gasket 500 are separate structures that are then fixedly connected. In actual settings, the sealing ring 400 and the gasket 500 can also be an integrated structure.

[0054] In addition, in this embodiment, a third conical surface fitting pair V3 is formed between the bushing 600 and the nut 300. It is understandable that in actual setting, it is also feasible not to form this fitting pair between the bushing 600 and the nut 300.

[0055] Please refer to Figures 3 to 14 , Figure 3 for Figure 1 Schematic diagram of the structure of the connecting pipe; Figure 4 for Figure 2 Schematic diagram of the structure of the middle nut; Figure 5 for Figure 4 A schematic cross-sectional view of the nut shown; Figure 6 for Figure 2 Schematic diagram of the structure of the middle sealing ring; Figure 7 for Figure 6 A schematic cross-sectional view of the sealing ring shown; Figure 8 for Figure 2 Schematic diagram of the structure of the middle washer; Figure 9 for Figure 8 A schematic cross-sectional view of the gasket shown; Figure 10 for Figure 2 Schematic diagram of the structure of the middle bushing; Figure 11 for Figure 10 A schematic cross-sectional view of the bushing shown; Figure 12 for Figure 2 Schematic diagram of the structure of the plastic isolation sleeve; Figure 13 for Figure 12 Front view of the plastic isolation sleeve shown.

[0056] In this embodiment, the inner cavity of the nut 300 includes a first hole section that cooperates with the tube body of the connecting pipe 200, a conical hole section connected to the first hole section, and a second hole section connected to the conical hole section. The aforementioned internal thread portion is formed in the second hole section. It can be understood that the aperture of the second hole section is adapted to the outer diameter of the valve body connecting pipe 112 of the valve body 110.

[0057] The wall surface of the tapered hole section is the inner tapered surface 310 of the nut 300 .

[0058] The bushing 600 includes a tapered portion 610 and a circular sleeve portion 620 connected to the tapered portion 610 . The tapered portion 610 has a second outer tapered surface 611 .

[0059] After the bushing 600 is sleeved on the nut 300 , the conical portion 610 thereof matches with the conical hole section of the nut 300 , and the circular sleeve portion 620 matches with the second hole section of the nut 300 .

[0060] Obviously, the second outer conical surface 611 of the conical portion 610 and the inner conical surface 310 of the nut 300 form the aforementioned third conical surface matching pair V3.

[0061] In this embodiment, the inner hole of the bushing 600 includes a first circular hole 630, a tapered hole 640 and a second circular hole 640 connected in sequence. In the illustrated scheme, the first circular hole 630 and the tapered hole 640 roughly correspond to the tapered portion 610, and the second circular hole 640 corresponds to the circular sleeve portion 620.

[0062] The plastic isolation sleeve 700 includes a cylindrical portion 710 and a conical cylindrical portion 720 connected to the cylindrical portion 710. After the plastic isolation sleeve 700 is placed on the connecting pipe 200, its conical cylindrical portion 720 cooperates with the flared section 210 of the connecting pipe 200, and the cylindrical portion 710 cooperates with the tube body of the connecting pipe 200; the conical cylindrical portion 720 has a third outer conical surface 721 and a second inner conical surface 722, and its second inner conical surface 722 and the first outer conical surface 211 of the flared section 210 form the aforementioned first conical surface matching pair V1.

[0063] After the connecting pipe 200, the plastic isolation sleeve 700, the nut 300 and the bushing 600 are matched, the first hole section of the nut 300 and the first circular hole 630 of the bushing 600 are matched with the cylindrical portion 710 of the plastic isolation sleeve 700, and the tapered cylindrical portion 720 of the plastic isolation sleeve 700 is matched with the tapered hole 640 of the bushing 600, that is, the tapered hole wall surface of the tapered hole 640 and the third outer conical surface 721 of the tapered cylindrical portion 720 form a second conical surface matching pair V2, and the second outer conical surface 611 of the tapered portion 610 of the bushing 600 and the first inner conical surface 310 of the nut 300 form the aforementioned third conical surface matching pair V3.

[0064] Combine Figure 2 When tightening the nut 300, the inner conical surface 310 of the nut 300 presses against the second outer conical surface 611 of the bushing 600, so that the conical hole wall surface of the conical hole 640 of the bushing 600 presses against the third outer conical surface 721 of the plastic isolation sleeve 700, thereby pressing the second inner conical surface 722 of the plastic isolation sleeve 700 against the first outer conical surface 211 of the flared section 210, and finally acting on the sealing ring 400, so that the small diameter portion 420 is pressed against the valve body connecting pipe portion 112 for sealing, and the flared section 210 is pressed against the large diameter portion 410 of the sealing ring 400 for sealing.

[0065] In this embodiment, when the nut 300 is threadedly connected to the valve body connecting pipe 112 through the thread pair S1, the end surface of the flared section 210 of the connecting pipe 200 abuts against the end surface of the large diameter portion 410 of the sealing ring 400 to form a second sealing structure M2.

[0066] On the basis of arranging the bushing 600 and the plastic isolation sleeve 700 between the connecting pipe 200 and the nut 300 , the taper of the first outer conical surface 211 of the flared section 210 of the connecting pipe 200 is smaller than the taper of the inner conical surface 310 of the nut 300 .

[0067] Compared with the prior art, in the structure provided by this embodiment, since the first outer conical surface 211 of the flared section 210 does not directly cooperate with the inner conical surface 310 of the nut 300, the tapers of the two do not need to be consistent. The taper of the flared section 210 of the connecting pipe 200 can be designed to be relatively small. In this way, when the connecting pipe 200 is an aluminum pipe, since its flaring degree is relatively small, it is not easy to cause flaring cracking.

[0068] Obviously, since the flared tube 210 of the connecting tube 200 needs to cooperate with the tapered cylindrical portion 720 of the plastic isolation sleeve 700, during assembly, the plastic isolation sleeve 700, the bushing 600 and the nut 300 can be assembled first, and then the end of the connecting tube 200 without the flared section 210 can be inserted from the second hole section of the nut 300 toward the first hole section into the assembled nut 300, bushing 600 and plastic isolation sleeve 700.

[0069] In a specific solution, for ease of assembly, the plastic isolation sleeve 700 is preferably interference fit with the nut 200 and the bushing 600 so that the relative positions of the three are fixed after assembly and are not easily misaligned during subsequent assembly of other components. Of course, a clearance fit is also possible.

[0070] In order to reduce the difficulty of assembly, the plastic isolation sleeve 700 and the connecting pipe 200 can be loosely fitted, and the circular sleeve portion 620 of the bushing 600 and the nut 300 can also be loosely fitted.

[0071] like Figure 2 As shown, in this embodiment, the end of the valve body connecting portion 112 has an outer conical surface 1121, and the end of the gasket 500 facing the valve body connecting portion 112 has an inner conical surface 510 adapted to the outer conical surface 1121. When the nut 300 and the valve body connecting portion 112 are threadedly connected through the thread pair S1, the outer end surface of the valve body connecting portion 112 abuts against the end surface of the small diameter portion 420 of the sealing ring 400 to form a first sealing structure M1.

[0072] The end of the valve body connecting portion 112 is configured as a tapered structure, which is beneficial for forming a seal between the valve body connecting portion 112 and the sealing ring 400 during connection.

[0073] In other embodiments, Figure 14 As shown, when the nut 300 and the valve body connecting portion 112 are threadedly connected through the thread pair S1, the end of the valve body connecting portion 112 can also extend into the small diameter portion 420 of the sealing ring 400, and the inner hole wall surface of the small diameter portion 420 abuts against the outer conical surface of the valve body connecting portion 112 to form a first sealing structure M1'.

[0074] In the specific solution, the small diameter portion 420 of the sealing ring 400 is interference fit with the gasket 500, so that the sealing effect can be improved. During assembly, the sealing ring 400 can be tightly fitted with the gasket 500 first, and then assembled with the already assembled connecting pipe 200, nut 300, bushing 600 and plastic isolation sleeve 700.

[0075] The large diameter portion 410 and the bushing 600 are clearance-matched to facilitate assembly.

[0076] In a specific solution, the washer 600 and the nut 300 can also be clearance-fitted to facilitate assembly, or, of course, interference-fitted. The washer 600 is also made of copper to improve the strength and reliability of the connection structure.

[0077] In a specific solution, the sealing ring 400 can be made of plastic material, preferably PTFE material, or rubber material, which has a certain elasticity and can improve the sealing effect between it and the flared section 210 and the valve body connecting pipe portion 112.

[0078] It should be noted that the pipeline connection structure provided by the present invention is exemplified as a pipeline connection structure composed of a stop valve and a pipeline, and the valve body and valve body connecting pipe part are the valve body and valve body connecting pipe part of the stop valve. Similarly, the pipeline connection structure can also be a connection structure composed of other joints and pipelines.

[0079] The above is a detailed introduction to a pipeline connection structure provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A pipeline connection structure, characterized in that: The valve body comprises a connecting pipe, a connecting tube and a nut; the connecting tube is made of aluminum, and the valve body connecting pipe and the nut have a threaded pair that cooperate with each other; the valve body further comprises a spacer, a sealing ring, a washer and a bushing, the sealing ring, the washer and the bushing being located in the inner cavity of the nut, the sealing ring and the washer being fixedly connected or forming an integral structure, the bushing being sleeved on the outer periphery of the sealing ring, and the nut and the bushing being made of copper; The end of the connecting pipe is formed with a flared section, the isolation sleeve is externally mounted on the connecting pipe, the nut and the bushing are externally mounted on the isolation sleeve, a first tapered surface fitting pair is formed between the flared section and the isolation sleeve, and a second tapered surface fitting pair is formed between the isolation sleeve and the bushing; One end of the sealing ring abuts against the connecting portion of the valve body to form a first sealing structure, and the other end abuts against the flared section to form a second sealing structure. Both the first sealing structure and the second sealing structure are non-conical surface seals.

2. The pipeline connection structure according to claim 1, characterized in that: The sealing ring includes a large diameter portion and a small diameter portion connected to the large diameter portion. The small diameter portion is inserted into the gasket, and the large diameter portion is inserted into the bushing.

3. The pipeline connection structure according to claim 2, characterized in that: The isolation sleeve is made of plastic material, and includes a cylindrical portion and a conical cylindrical portion connected to the cylindrical portion. The inner conical surface of the conical cylindrical portion and the outer conical surface of the flared section form the first conical surface matching pair.

4. The pipeline connection structure according to claim 3, characterized in that: The bushing includes a tapered portion and a circular sleeve portion connected to the tapered portion, the circular sleeve portion cooperates with the inner hole of the nut, and the outer conical surface of the tapered portion and the inner conical surface of the nut form a third tapered surface matching pair; The bushing has a first circular hole, a tapered hole and a second circular hole connected in sequence, the inner diameter of the first circular hole is adapted to the outer diameter of the cylindrical part, the inner diameter of the second circular hole is adapted to the outer diameter of the large diameter part, and the tapered hole wall surface of the tapered hole and the outer tapered surface of the tapered cylindrical part form the second tapered surface matching pair.

5. The pipeline connection structure according to claim 4, characterized in that: The circular sleeve portion is clearance-fitted with the nut, the plastic isolation sleeve is interference-fitted with the nut, and the plastic isolation sleeve is also interference-fitted with the bushing.

6. The pipeline connection structure according to claim 4, characterized in that: The taper of the outer conical surface of the flared section is smaller than the taper of the inner conical surface of the nut.

7. The pipeline connection structure according to any one of claims 2 to 6, characterized in that: When the nut is threadedly connected to the connecting pipe portion of the valve body through the thread pair, the end surface of the flared section abuts against the end surface of the large-diameter portion to form the second sealing structure.

8. The pipeline connection structure according to claim 7, characterized in that: The end of the valve body connecting pipe part has an outer conical surface, and the end of the gasket facing the valve body connecting pipe part has an inner conical surface adapted to the outer conical surface; when the nut and the valve body connecting pipe part are threadedly connected through the thread pair, the outer end surface of the valve body connecting pipe part abuts against the end surface of the small diameter part to form the first sealing structure.

9. The pipeline connection structure according to claim 7, characterized in that: The end of the valve body connecting pipe part has an outer conical surface, and the end of the gasket facing the valve body connecting pipe part has an inner conical surface adapted to the outer conical surface; the end of the valve body connecting pipe part extends into the small diameter part, and the inner hole wall surface of the small diameter part abuts against the outer conical surface to form the first sealing structure.

10. The pipeline connection structure according to any one of claims 2 to 6, characterized in that: The small diameter portion is interference fit with the washer, and the large diameter portion is clearance fit with the bushing.

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