A straight pipe pressure balance expansion joint with a floating structure

Abstract

The present invention provides a straight pipe pressure balance expansion joint with a floating structure, which includes a main pipe body and a balance pipe assembly. In the radial direction, the balance pipe assembly is sleeved outside the main pipe body, and the main pipe body is communicated with the balance pipe assembly for displacement compensation. A floating limit structure is arranged outside the main pipe body. The balance pipe assembly includes a floating structure, and the floating structure is connected to the floating limit structure, and relative lateral displacement can occur between the floating structure and the floating limit structure, so that the whole balance pipe assembly can perform relative lateral displacement with respect to the main pipe body. The present invention not only improves the lateral displacement margin of the expansion joint and increases the lateral compensation ability of the expansion joint, but also the balance pipe assembly does not participate in radial deformation, which is also beneficial to reducing the radial stiffness in the whole expansion joint.

Description

Technical Field

[0001] The present invention relates to the technical field of expansion joints, and particularly to a straight pipe pressure balance type expansion joint with a floating structure. Background Art

[0002] In the expansion joint standard GB / T12777 General Technical Conditions for Metallic Bellows Expansion Joints in China, the straight pipe pressure balance type expansion joint is defined as: an expansion joint composed of two working bellows at both ends, a balance bellows in the middle, tie rods, end plates and other structural components, which is mainly used to absorb axial displacement and balance the pressure thrust of the bellows. At the same time, in industrial applications, in order to avoid the pressure thrust generated by the unconstrained bellows expansion joint acting on the equipment and affecting the normal operation of the equipment, the straight pipe pressure balance type bellows expansion joint is usually selected to restrain the pressure thrust.

[0003] As shown in the Figure 1 accompanying figure, the existing conventional straight pipe pressure balance type bellows expansion joint is composed of two groups of working bellows B, a balance bellows D in the middle, tie rods C, a first end plate E, a second end plate F and other structural components, which is mainly used to absorb the axial direction and balance the pressure thrust of the bellows. When the conventional straight pipe pressure balance type bellows expansion joint compensates for the lateral displacement, the three groups of bellows (two groups of working bellows and one group of balance bellows) distribute the displacement according to the stiffness ratio, and the large-amplitude lateral displacement compensation function and compensation requirements of the compound bellows cannot be realized. Within the limited length dimension range, the lateral displacement compensation ability is very limited, and the stiffness in the expansion joint is relatively large, resulting in a large acting force on the equipment nozzle.

[0004] Therefore, on the premise of the given compensation requirements of the pipeline, the expansion joint often requires a longer installation dimension, which will undoubtedly cause space conflicts in some cases and bring inconvenience to the layout of pipeline components, equipment, etc. In addition, on the premise of the given allowable installation dimension of the pipe system, due to the relatively large stiffness during the lateral displacement compensation of the conventional expansion joint, it is often necessary to enhance the strength of the pipe system restraint structure or the strength of the equipment nozzle. Both of the above situations will increase the construction cost.

[0005] In order to solve the related problems in the process of lateral displacement compensation of conventional expansion joints, various expansion joints for realizing the lateral displacement compensation of pipelines have been proposed in the prior art. For example, CN201520791414.0 discloses a straight pipe pressure balance type compensator, in which one of the working bellows is designed as a compound bellows, and the compound bellows can increase the lateral displacement compensation ability by controlling the effective length. Similarly, the applicant has also carried out corresponding research. Taking the applicant's early patent CN201810008621.2 as an example, it discloses a pressure balance type expansion joint based on end face sliding seal compensation technology. By setting an end face sliding seal compensation structure, the lateral displacement compensation ability of the pressure balance type expansion joint is improved, and at the same time, the force on the end flange used for the end face sliding seal is reduced.

[0006] However, with the continuous research of the applicant, the straight pipe pressure balance type bellows expansion joints in the prior art often achieve lateral displacement compensation by bending or angular deflection in the radial direction of each single group of working bellows. Although this can achieve the lateral displacement compensation of the pipeline to a certain extent, the conventional straight pipe pressure balance type bellows expansion joints not only often have the problems of too long expansion joint length, which is not conducive to reducing the weight and cost of the expansion joint, but also have the problem of relatively limited lateral displacement ability. Even under the action of radial force, due to insufficient bending space margin or angular deflection margin, the lateral displacement ability is insufficient, resulting in radial deformation of the local structure of the expansion joint and a relatively large stiffness in the expansion joint. Summary of the Invention

[0007] In view of this, the present invention aims to propose a straight pipe pressure balance type expansion joint with a floating structure to solve the problems of relatively limited lateral displacement ability and relatively large stiffness of the conventional straight pipe pressure balance type bellows expansion joints in the prior art.

[0008] To achieve the above object, the technical solution of the present invention is realized as follows:

[0009] A straight pipe pressure balance type expansion joint with a floating structure includes a main pipe body and a balance pipe assembly. In the radial direction, the balance pipe assembly is sleeved outside the main pipe body, and the main pipe body is communicated with the balance pipe assembly for displacement compensation. A floating limit structure is arranged outside the main pipe body. The balance pipe assembly includes a floating structure, and the floating structure is connected to the floating limit structure, and relative lateral displacement can occur between the floating structure and the floating limit structure, so that the entire balance pipe assembly can perform relative lateral displacement with respect to the main pipe body.

[0010] Furthermore, the floating limit structure includes a first limit member and a second limit member, and the floating structure includes a first floating member and a second floating member. One end of the main pipe body is provided with the first limit member, and the other end is provided with the second limit member; a second floating member is provided at one end of the balance pipe assembly close to the first limit member, and the second floating member is clamped with the second limit member, and relative lateral displacement can occur between the second floating member and the second limit member; a first floating member is provided at one end of the balance pipe assembly close to the second limit member, and the first floating member is clamped with the first limit member, and relative lateral displacement can occur between the first floating member and the first limit member.

[0011] Furthermore, rolling members are provided between the first floating member and the first limit member, and rolling members are provided between the second floating member and the second limit member.

[0012] Furthermore, a first flange is provided at one end of the main pipe body, and a second flange is provided at the other end. The main pipe body is connected to external pipes through the first flange and the second flange respectively.

[0013] Furthermore, a first connection ring and a first fixing plate are provided on the side of the first flange facing the second flange. One side of the first connection ring is connected to the first flange, and the other side is connected to the first fixing plate. A first annular cavity is formed among the first flange, the first connection ring, and the first fixing plate; a second connection ring and a second fixing plate are provided on the side of the second flange facing the first flange. One side of the second connection ring is connected to the second flange, and the other side is connected to the second fixing plate. A second annular cavity is formed among the second flange, the second connection ring, and the second fixing plate.

[0014] Furthermore, the first floating member includes a second balance floating ring plate, a first connecting rod, and a first sliding ring. The second balance floating ring plate is arranged at one end of the balance pipe assembly close to the second flange. One end of the first connecting rod is connected to the second balance floating ring plate, and the other end extends towards the first flange and is connected to the first sliding ring. At least part of the structure of the first sliding ring is arranged in the first annular cavity and can perform lateral displacement relative to the first annular cavity; the second floating member includes a first balance floating ring plate, a second connecting rod, and a second sliding ring. The first balance floating ring plate is arranged at one end of the balance pipe assembly close to the first flange. One end of the second connecting rod is connected to the first balance floating ring plate, and the other end extends towards the second flange and is connected to the second sliding ring. At least part of the structure of the second sliding ring is arranged in the second annular cavity and can perform lateral displacement relative to the second annular cavity.

[0015] Further, in the first annular cavity, balls are arranged between the first sliding ring and the first flange, and balls are arranged between the first sliding ring and the first fixing plate; in the second annular cavity, balls are arranged between the second sliding ring and the second flange, and balls are arranged between the second sliding ring and the second fixing plate.

[0016] Further, the first balance floating ring plate and / or the second balance floating ring plate are provided with avoidance holes, the first connecting rod passes through the avoidance hole of the first balance floating ring plate, and / or the second connecting rod passes through the avoidance hole of the second balance floating ring plate.

[0017] Further, the balance pipe assembly includes an outer balance bellows and an inner balance bellows. In the radial direction, the inner balance bellows is sleeved outside the main pipe body, the outer balance bellows is sleeved outside the inner balance bellows, and a balance cavity is formed between the outer balance bellows and the inner balance bellows.

[0018] Further, on one side close to the first flange, both the outer balance bellows and the inner balance bellows are connected to the first balance floating ring plate; on one side close to the second flange, both the outer balance bellows and the inner balance bellows are connected to the second balance floating ring plate.

[0019] Compared with the prior art, the straight pipe pressure balance type expansion joint with a floating structure of the present invention has the following advantages:

[0020] For the straight pipe pressure balance type expansion joint with a floating structure of the present invention, if the main pipe body undergoes a lateral movement, the overall lateral displacement of the balance pipe assembly can be driven by the relative lateral displacement between the floating limit structure and the floating structure. Compared with the prior art, the balance pipe assembly will not bend or deflect at an angle, but the entire balance pipe assembly directly undergoes a lateral displacement relative to the main pipe body in the radial direction, and the entire balance pipe assembly will not undergo any radial deformation. Correspondingly, the entire balance pipe assembly will not generate lateral stiffness. In addition, due to the setting of the floating structure and other related components, the working bellows of the main pipe body can compensate for the lateral displacement according to the compound free type structure. Therefore, the present application not only improves the lateral displacement margin of the expansion joint and increases the lateral compensation ability of the expansion joint, but also the expansion joint is not prone to radial deformation, which is also beneficial to reducing the radial stiffness in the overall expansion joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0022] Figure 1 is a schematic structural diagram of a conventional straight pipe pressure balance type expansion joint in the prior art;

[0023] Figure 2 This is a schematic structural diagram of a straight pipe pressure-balanced expansion joint with a floating structure according to an embodiment of the present invention;

[0024] Figure 3 Another structural schematic diagram of a straight pipe pressure balanced expansion joint with a floating structure described in an embodiment of the present invention.

[0025] Description of reference numerals:

[0026] A. End pipe; B. Working bellows; C. Pull rod; D. Balancing bellows; E. First end plate; F. Second end plate; 1. First flange; 2. First connecting ring; 3. First sliding ring; 4. Ball; 5. First fixed plate; 6. Working bellows; 7. Connecting pipe; 8. First balancing floating ring plate; 9. Intermediate pipe; 10. External balancing bellows; 11. Internal balancing bellows; 12. First connecting rod; 13. Second balancing floating ring plate; 14. Second connecting rod; 15. Connecting pipe; 16. Second flange; 17. Second connecting ring; 18. Second sliding ring; 19. Second fixed plate. DETAILED DESCRIPTION

[0027] The inventive concepts of the present disclosure will be described below using terms commonly used by those skilled in the art to convey the essence of their work to other persons skilled in the art. However, these inventive concepts can be embodied in many different forms and should not be considered limited to the embodiments described herein.

[0028] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The radial, axial and other terms used in this application are all based on the central axis of the expansion joint (corresponding to the attached Figures 1-3 The center line represented by the dotted line in the figure is used as a reference, and the axial direction corresponds to the direction in which the central axis extends. On any section perpendicular to the axial direction, any extension direction of the expansion joint diameter is radial, which is consistent with the conventional cognition and naming in this field and will not be repeated. In this application, the displacement in the axial direction is called "axial displacement", and any displacement in the radial direction is called "lateral displacement", and the stress in the radial direction is called "lateral stiffness"; the radial direction and the lateral direction in this application are the same direction.

[0029] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0030] Example 1

[0031] In the straight pipe pressure balance type bellows expansion joint in the prior art, although it can achieve lateral displacement compensation of the pipeline to a certain extent, the conventional straight pipe pressure balance type bellows expansion joint often has problems such as a relatively long length of the expansion joint, which is not conducive to reducing the weight and cost of the expansion joint. At the same time, the conventional expansion joint often realizes lateral displacement compensation by bending or angular deflection in the radial direction of each single group of working bellows. This makes the expansion joint in the prior art have the problem of relatively limited lateral displacement ability. Even under the action of radial force, due to insufficient bending space margin or angular deflection margin, its lateral displacement ability is insufficient, resulting in radial deformation of the local structure of the expansion joint and a relatively large stiffness in the expansion joint.

[0032] In order to solve the problems in the prior art that the lateral displacement ability of the conventional straight pipe pressure balance type bellows expansion joint is relatively limited, which easily leads to radial deformation of the expansion joint and a relatively large stiffness in the expansion joint, this embodiment proposes a straight pipe pressure balance type expansion joint with a floating structure, as shown in the appendix Figures 2-3 As shown, the expansion joint includes a main pipe body and a balance pipe assembly. In the radial direction, the balance pipe assembly is sleeved outside the main pipe body. Both the main pipe body and the balance pipe assembly can at least perform axial displacement, and the main pipe body is communicated with the balance pipe assembly, at least for axial displacement compensation. This is basically the same as the axial displacement compensation principle of the conventional straight pipe pressure balance type expansion joint and will not be elaborated. Of course, for this expansion joint, in addition to axial displacement compensation, this application focuses on introducing the relevant technical content of its lateral displacement compensation.

[0033] A floating limit structure is arranged outside the main pipe body, and a floating structure is arranged on the balance pipe assembly. The floating structure is connected to the floating limit structure, and relative lateral displacement can occur between the floating structure and the floating limit structure, so that the entire balance pipe assembly can perform relative lateral displacement with the main pipe body.

[0034] During the installation and use process of the expansion joint of this application, if the main pipe body undergoes lateral movement, the relative lateral displacement between the floating limit structure and the floating structure can be used to drive the lateral displacement of the entire balance pipe assembly. Compared with the prior art, the balance pipe assembly will not bend or deflect angularly, but the entire balance pipe assembly directly performs lateral displacement relative to the main pipe body in the radial direction, and no radial deformation will occur to the entire balance pipe assembly. Correspondingly, no lateral stiffness will be generated in the entire balance pipe assembly. Therefore, this application not only improves the lateral displacement margin of the expansion joint and increases the lateral compensation ability of the expansion joint, but also the expansion joint is not prone to radial deformation and is beneficial to reducing the radial stiffness in the overall expansion joint.

[0035] The expansion joint includes a connecting pipe 7. The main pipe body has a main flow channel. The balance pipe assembly has a sealed balance cavity, and the balance cavity is communicated with the main flow channel through the connecting pipe 7. That is, one end of the connecting pipe 7 is communicated with the main flow channel, and the other end is communicated with the balance cavity, so as to introduce the medium in the main flow channel into the sealed balance cavity, so as to realize the axial displacement compensation of the expansion joint through pressure balance. Preferably, the connecting pipe 7 is a flexible pressure-bearing hollow pipe, and a certain amount of length margin can be set. On the one hand, it is used to form a medium flow channel. On the other hand, when there is an axial relative displacement and / or a radial relative displacement between the main pipe body and the balance pipe assembly, the long enough connecting pipe 7 can provide a certain extension distance to meet the normal use of the expansion joint.

[0036] Considering factors such as simplifying the structure of the expansion joint, reducing the length of the expansion joint, and reducing its weight and cost, the present application is not limited to proposing the relevant structure for lateral displacement compensation. Through further research by the researchers of the present application, the structure of the expansion joint is further improved.

[0037] The floating limit structure includes a first limit member and a second limit member. The floating structure includes a first floating member and a second floating member. One end of the main pipe body is provided with a first limit member, and the other end is provided with a second limit member. A second floating member is arranged at one end of the balance pipe assembly close to the first limit member. The second floating member is clamped with the second limit member, and relative lateral displacement can occur between the second floating member and the second limit member. A first floating member is arranged at one end of the balance pipe assembly close to the second limit member. The first floating member is clamped with the first limit member, and relative lateral displacement can occur between the first floating member and the first limit member.

[0038] Rolling members are arranged between the first floating member and the first limit member, and rolling members are arranged between the second floating member and the second limit member, so that relative lateral displacement between the first floating member and the first limit member, and between the second floating member and the second limit member can be carried out more simply and easily. The rolling member is preferably a ball 4.

[0039] Thus, relative lateral displacement can occur between the second floating member and the second limiting member, and between the first floating member and the first limiting member. On the basis of ensuring the lateral displacement compensation function of the expansion joint, the axial force between the first floating member and the first limiting member is denoted as F1, and the axial force between the second floating member and the second limiting member is denoted as F2. Through the setting of the floating structure and the limitation of the connection relationship, during the axial displacement compensation process of the expansion joint, as the pressure balance and axial movement of the main pipe body and the balance pipe assembly occur, F1 and F2 reach equal magnitudes and opposite directions, achieving force balance, so that the expansion joint can also realize the axial displacement compensation function of the expansion joint through the floating structure provided in this application. That is, through the setting of the floating structure in this application, not only can the axial displacement compensation function and the lateral displacement compensation function of the expansion joint be realized simultaneously, but also the force balance during the axial displacement compensation can be satisfied, which is beneficial to simplifying the structure of the expansion joint itself, can effectively reduce the length of the expansion joint, and is beneficial to reducing the weight and production cost of the expansion joint.

[0040] Regarding the specific setting of the floating limiting structure, one end of the main pipe body is provided with a first flange 1, and the other end is provided with a second flange 16. One side of the first flange 1 is connected to an external pipeline, and the other side (the side facing the second flange 16) is provided with a first connection ring 2 and a first fixing plate 5. One side of the first connection ring 2 is connected to the first flange 1, and the other side is connected to the first fixing plate 5. A first annular cavity is formed between the first flange 1, the first connection ring 2, and the first fixing plate 5. At this time, the first flange 1, the first connection ring 2, the first fixing plate 5, and the first annular cavity formed by them can be regarded as the first limiting member. One side of the second flange 16 is connected to an external pipeline, and the other side (the side facing the first flange 1) is provided with a second connection ring 17 and a second fixing plate 19. One side of the second connection ring 17 is connected to the second flange 16, and the other side is connected to the second fixing plate 19. A second annular cavity is formed between the second flange 16, the second connection ring 17, and the second fixing plate 19. At this time, the second flange 16, the second connection ring 17, the second fixing plate 19, and the second annular cavity formed by them can be regarded as the second limiting member.

[0041] Regarding the specific setting of the floating structure, the first floating member includes a second balanced floating ring plate 13, a first connecting rod 12, and a first sliding ring 3. The second balanced floating ring plate 13 is arranged at one end of the balance pipe assembly close to the second flange 16. One end of the first connecting rod 12 is connected to the second balanced floating ring plate 13, and the other end extends towards the first flange 1 and is connected to the first sliding ring 3. At least part of the structure of the first sliding ring 3 is arranged in the first annular cavity and can perform a lateral displacement relative to the first annular cavity, so that at least on the basis of the assembly structure on the side of the first flange 1, the balance pipe assembly can perform a lateral displacement relative to the first limiting member through the first floating member. Preferably, in the first annular cavity, balls 4 are arranged between the first sliding ring 3 and the first flange 1, and balls 4 are arranged between the first sliding ring 3 and the first fixed plate 5, so that in the first annular cavity, the first sliding ring 3 can perform a lateral displacement with the first limiting member through the balls 4.

[0042] The second floating member includes a first balanced floating ring plate 8, a second connecting rod 14, and a second sliding ring 18. The first balanced floating ring plate 8 is arranged at one end of the balance pipe assembly close to the first flange 1. One end of the second connecting rod 14 is connected to the first balanced floating ring plate 8, and the other end extends towards the second flange 16 and is connected to the second sliding ring 18. At least part of the structure of the second sliding ring 18 is arranged in the second annular cavity and can perform a lateral displacement relative to the second annular cavity, so that at least on the basis of the assembly structure on the side of the second flange 16, the balance pipe assembly can perform a lateral displacement relative to the second limiting member through the second floating member. Preferably, in the second annular cavity, balls 4 are arranged between the second sliding ring 18 and the second flange 16, and balls 4 are arranged between the second sliding ring 18 and the second fixed plate 19, so that in the second annular cavity, the second sliding ring 18 can perform a lateral displacement with the second limiting member through the balls 4.

[0043] Regarding the balls 4 in the first annular cavity and the second annular cavity, they are evenly distributed between the corresponding components. The balls 4 can rotate freely and can roll within a certain range.

[0044] Since there is a situation where the extending directions of the components are opposite to each other during the assembly of the first floating member and the second floating member, especially the first connecting rod 12 and the second connecting rod 14, in order to avoid unnecessary spatial interference, the first balanced floating ring plate 8 and / or the second balanced floating ring plate 13 are provided with avoidance holes, and the first connecting rod 12 passes through the avoidance hole of the first balanced floating ring plate 8, and / or the second connecting rod 14 passes through the avoidance hole of the second balanced floating ring plate 13; the specific setting situation should be determined according to the actual radial dimensions of the relevant components, and is not limited to the attachment of this application. Figure 2 、 3Structural schematic in it. At the same time, for the component structures that will not cause spatial interference, the avoidance holes may not be set.

[0045] Thus, by setting the limiting member structures at both ends of the expansion joint and setting the corresponding floating member structures at both ends of the balance pipe assembly, and the extending directions of the first connecting rod 12 and the second connecting rod 14 in the floating member structure are opposite, the force balance during the axial displacement compensation can be satisfied to achieve the axial displacement compensation function of the expansion joint; at the same time, through the lateral displacement of the first sliding ring 3 relative to the first ring cavity and the lateral displacement of the second sliding ring 18 relative to the second ring cavity, the balance pipe assembly can perform lateral displacement compensation through the first floating member and the second floating member at the same time, that is, the entire balance pipe assembly can directly perform lateral displacement relative to the main pipe body, rather than achieving lateral displacement through bending or angular deflection, etc. At the same time, due to the setting of the floating structure and other related components, the working bellows of the main pipe body can compensate for lateral displacement according to the compound free type structure, which can greatly improve the lateral displacement margin of the expansion joint, increase the lateral compensation ability of the expansion joint, and the entire balance pipe assembly performs an overall radial movement without any radial deformation, and it also makes the entire expansion joint not easily undergo radial deformation, which is beneficial to reducing the radial stiffness in the whole expansion joint.

[0046] In addition to the first floating member and the second floating member, the balance pipe assembly includes an outer balance bellows 10 and an inner balance bellows 11. In the radial direction, the inner balance bellows 11 is sleeved on the outside of the main pipe body, the outer balance bellows 10 is sleeved on the outside of the inner balance bellows 11, and a balance cavity is formed between the outer balance bellows 10 and the inner balance bellows 11. Correspondingly, the balance cavity is an annular cavity.

[0047] On the side close to the first flange 1, both the outer balance bellows 10 and the inner balance bellows 11 are connected to the first balance floating ring plate 8. On the side close to the second flange 16, both the outer balance bellows 10 and the inner balance bellows 11 are connected to the second balance floating ring plate 13. And under the blocking action of the first balance floating ring plate 8 and the second balance floating ring plate 13, the balance cavity between the outer balance bellows 10 and the inner balance bellows 11 is sealed together, so that the balance cavity can be in a relatively airtight state, and the balance cavity is only connected to the main flow channel of the main pipe body through the connecting pipe 7.

[0048] Regarding the specific installation situation of the connecting pipe 7, the main pipe body is provided with a first connection hole, the first balance floating ring plate 8 or the second balance floating ring plate 13 is provided with a second connection hole, one end of the connecting pipe 7 is connected to the first connection hole, and the other end is connected to the second connection hole. Thus, through the installation of the connecting pipe 7, the balance cavity is connected to the main flow channel of the main pipe body.

[0049] Meanwhile, considering that the balance pipe assembly needs to accommodate both axial displacement and lateral displacement, for the assembly of the balance pipe assembly, in addition to the connection relationship of the connecting pipe 7, the assembly relationship between the first sliding ring 3 and the first ring cavity, and the assembly relationship between the second sliding ring 18 and the second ring cavity, the balance pipe assembly is not connected to any other components of non-balance pipe assemblies. In particular, the inner balance bellows 11 does not contact the main pipe body, and the first balance floating ring plate 8 and the second balance floating ring plate 13 also do not contact the main pipe body. This ensures that during axial displacement or lateral displacement of the balance pipe assembly, there is no movement obstruction and no spatial interference, ensuring the normal installation and use of the expansion joint.

[0050] The same as the prior art, at least part of the pipe section of the main pipe body is the working bellows 6.

[0051] In the working state of the expansion joint, the expansion joint is connected to the external pipeline through the first flange 1 and the second flange 16. The main pipe body is filled with a medium with a pressure of p. At the same time, the medium enters the balance cavity between the outer balance bellows 10 and the inner balance bellows 11 through the connecting pipe 7, and the pressure in the balance cavity is also p. In the assembly structure of the floating limit structure and the floating structure in this application, to achieve pressure thrust balance, under the action of the working bellows 6, the outer balance bellows 10, and the inner balance bellows 11, the annular effective area of the balance cavity is equal to the effective area of the working bellows 6, that is, Ap1 - Ap2 = Ag, where Ap1 is the effective area of the outer balance bellows 10, Ap2 is the effective area of the inner balance bellows 11, and Ag is the effective area of the working bellows 6.

[0052] At this time, in the balance cavity, both the first balance floating ring plate 8 and the second balance floating ring plate 13 are in contact with the medium. The pressure thrust generated by the medium on the first balance floating ring plate 8 is equal in magnitude and opposite in direction to the pressure thrust on one side of the second flange 16, and force conduction is carried out through the second connecting rod 14, the second sliding ring 18, the ball 4, the second fixing plate 19, the second connecting ring 17, and the second flange 16, so as to achieve force balance with the pressure thrust on one side of the second flange 16; the balance of the pressure thrust generated by the medium on the second balance floating ring plate 13 is the same as that of the first balance floating ring plate 8 and will not be elaborated here.

[0053] Regarding the displacement compensation method of the expansion joint of this application:

[0054] (1) Compensating axial displacement: The method for the expansion joint of this application to compensate axial displacement is basically the same as the axial compensation method of a conventional straight pipe pressure balance type expansion joint. The displacement amounts of the outer balance bellows 10 and the inner balance bellows 11 are equal to the total displacement amount of the working bellows 6.

[0055] (2) Compensation for lateral displacement: For the main pipe body, a compound pipe structure is composed of the working bellows 6 and other pipe section structures, and the lateral displacement is compensated in the manner of a compound free-type expansion joint. At this time, the first flange 1 and the second flange 16 undergo lateral relative movement, and the first sliding ring 3 and the second sliding ring 18 undergo radial movement by forming a rolling friction structure with the balls 4, so that the entire balance pipe assembly undergoes overall radial displacement under the action of the balls 4. The entire balance pipe assembly does not participate in any radial deformation and will not generate lateral stiffness; only the working bellows 6 of the main pipe body in the entire expansion joint generates lateral stiffness according to the compound free-type structure.

[0056] Embodiment 2

[0057] On the basis of Embodiment 1, this embodiment introduces the structure of the main pipe body and related assembly conditions.

[0058] As shown in the appendix Figure 2 As shown, the main pipe body includes an intermediate pipe 9. Working bellows 6 are arranged at both ends of the intermediate pipe 9, and the intermediate pipe 9 is respectively connected to the first flange 1 and the second flange 16 through the working bellows 6. Correspondingly, the intermediate pipe 9 is provided with a first connection hole, and the connecting pipe 7 is connected to the first connection hole.

[0059] Embodiment 3

[0060] On the basis of Embodiment 1, this embodiment introduces another implementation manner of the structure of the main pipe body and related assembly conditions.

[0061] As shown in the appendix Figure 3 As shown, the main pipe body includes a working bellows 6. Connecting pipes 15 are arranged at both ends of the working bellows 6, and the working bellows 6 is respectively connected to the first flange 1 and the second flange 16 through the connecting pipes 15. Correspondingly, at least one of the two connecting pipes 15 is provided with a first connection hole, and the connecting pipe 7 is connected to the first connection hole.

[0062] Meanwhile, the first flange 1 and the corresponding connecting pipe 15 are preferably integrally formed, and the second flange 16 and the corresponding connecting pipe 15 are preferably integrally formed to improve the connection strength of the expansion joint, reduce the number of components of the expansion joint, lower the production cost, and improve the production and assembly efficiency.

[0063] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A straight pipe pressure balance expansion joint with a floating structure, characterized in that, The expansion joint includes a main pipe body and a balance pipe assembly. In the radial direction, the balance pipe assembly is sleeved outside the main pipe body, and the main pipe body is communicated with the balance pipe assembly for displacement compensation. A floating limit structure is arranged outside the main pipe body. The balance pipe assembly includes a floating structure, and the floating structure is connected with the floating limit structure, and relative lateral displacement can occur between the floating structure and the floating limit structure, so that the whole balance pipe assembly can perform relative lateral displacement with the main pipe body. The floating limit structure includes a first limit member and a second limit member. The floating structure includes a first floating member and a second floating member. The first limit member is arranged at one end of the main pipe body, and the second limit member is arranged at the other end. The second floating member is arranged at one end of the balance pipe assembly close to the first limit member. The second floating member is clamped with the second limit member, and relative lateral displacement can occur between the second floating member and the second limit member. The first floating member is arranged at one end of the balance pipe assembly close to the second limit member. The first floating member is clamped with the first limit member, and relative lateral displacement can occur between the first floating member and the first limit member. Rolling members are arranged between the first floating member and the first limit member, and rolling members are arranged between the second floating member and the second limit member. A first flange (1) is arranged at one end of the main pipe body, and a second flange (16) is arranged at the other end. The main pipe body is respectively connected to external pipelines through the first flange (1) and the second flange (16).

2. The straight pipe pressure balance expansion joint with a floating structure according to claim 1, characterized in that, A first connection ring (2) and a first fixing plate (5) are arranged on one side of the first flange (1) facing the second flange (16). One side of the first connection ring (2) is connected to the first flange (1), and the other side is connected to the first fixing plate (5). A first annular cavity is formed among the first flange (1), the first connection ring (2), and the first fixing plate (5). A second connection ring (17) and a second fixing plate (19) are arranged on one side of the second flange (16) facing the first flange (1). One side of the second connection ring (17) is connected to the second flange (16), and the other side is connected to the second fixing plate (19). A second annular cavity is formed among the second flange (16), the second connection ring (17), and the second fixing plate (19).

3. The straight pipe pressure balance expansion joint with a floating structure according to claim 2, characterized in that, The first floating member includes a second balanced floating ring plate (13), a first connecting rod (12), and a first sliding ring (3). The second balanced floating ring plate (13) is arranged at one end of the balance pipe assembly close to the second flange (16). One end of the first connecting rod (12) is connected to the second balanced floating ring plate (13), and the other end extends towards the first flange (1) and is connected to the first sliding ring (3). At least part of the structure of the first sliding ring (3) is arranged in the first ring cavity and can perform lateral displacement relative to the first ring cavity. The second floating member includes a first balanced floating ring plate (8), a second connecting rod (14), and a second sliding ring (18). The first balanced floating ring plate (8) is arranged at one end of the balance pipe assembly close to the first flange (1). One end of the second connecting rod (14) is connected to the first balanced floating ring plate (8), and the other end extends towards the second flange (16) and is connected to the second sliding ring (18). At least part of the structure of the second sliding ring (18) is arranged in the second ring cavity and can perform lateral displacement relative to the second ring cavity.

4. The straight pipe pressure balance expansion joint with a floating structure according to claim 3, characterized in that, In the first ring cavity, balls (4) are arranged between the first sliding ring (3) and the first flange (1), and balls (4) are arranged between the first sliding ring (3) and the first fixing plate (5). In the second ring cavity, balls (4) are arranged between the second sliding ring (18) and the second flange (16), and balls (4) are arranged between the second sliding ring (18) and the second fixing plate (19).

5. The straight pipe pressure balance expansion joint with a floating structure according to claim 3, characterized in that, The first balanced floating ring plate (8) and / or the second balanced floating ring plate (13) are provided with avoidance holes. The first connecting rod (12) penetrates through the avoidance hole of the first balanced floating ring plate (8), and / or the second connecting rod (14) penetrates through the avoidance hole of the second balanced floating ring plate (13).

6. The straight pipe pressure balance expansion joint with a floating structure according to claim 3, characterized in that, The balance pipe assembly includes an outer balance bellows (10) and an inner balance bellows (11). In the radial direction, the inner balance bellows (11) is sleeved outside the main body, and the outer balance bellows (10) is sleeved outside the inner balance bellows (11). A balance cavity is formed between the outer balance bellows (10) and the inner balance bellows (11).

7. The straight pipe pressure balance expansion joint with a floating structure according to claim 6, characterized in that, On the side close to the first flange (1), both the outer balance bellows (10) and the inner balance bellows (11) are connected to the first balanced floating ring plate (8). On the side close to the second flange (16), both the outer balance bellows (10) and the inner balance bellows (11) are connected to the second balanced floating ring plate (13).

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