Follow-up bellows compensator

Abstract

A follower-type bellows compensator is used to compensate for the thermal expansion and contraction of pipelines. It includes a working bellows (5), a first connecting pipe (1) and a first ring plate (2) welded to the left end of the working bellows, a second connecting pipe (20) and a second ring plate (7) welded to the right end, a third ring plate (10) fitted on the second connecting pipe, a plurality of tie rods (4) symmetrically connected to the first ring plate at their left ends, a balance bellows sealed between the second ring plate and the third ring plate, a flow guide pipe (6) of the annular cavity of the balance bellows communicating with the second connecting pipe, a fourth ring plate (15) fixedly connected to the right end of the tie rods, a plurality of follower devices symmetrically provided between the fourth ring plate and the third ring plate, the follower devices enabling the second ring plate and the third ring plate to move synchronously along the axial direction, the beneficial effect of which is that the length of the balance bellows can be minimized, while only one working bellows is required, which is conducive to reducing production costs; at the same time, the length of the compensator is reduced, which facilitates transportation and installation.

Description

Technical Field

[0001] This invention relates to a bellows compensator used to compensate for the thermal expansion and contraction of pipelines. Background Technology

[0002] A bellows compensator comprises a bellows with connecting pipes at both ends. These connecting pipes are connected in series in a pipeline. The fluid medium in the bellows exerts a thrust on the bellows, which is transmitted through the pipeline to connected external equipment. Since the external equipment is fixed on a support, this thrust can damage the support. To prevent the thrust from being output outward, existing technology often uses a balanced bellows compensator, which has three bellows: a first working bellows, a second working bellows, and a balanced bellows. The right end of the first working bellows is connected to the left end of the balanced bellows, and the right end of the balanced bellows is connected to the left end of the second working bellows. A tie rod connects the left ends of the first and second working bellows, and a tie rod also connects the right ends of the first and second working bellows. The average cross-sectional area of ​​the balanced bellows is twice that of the first working bellows, and the first and second working bellows have the same structure. Balanced bellows compensators require the use of three bellows, which greatly increases their length and outer diameter. Summary of the Invention

[0003] The purpose of this invention is to reduce the number of bellows used and the volume of the bellows compensator while preventing the thrust of the compensator from being output outward.

[0004] The technical solution of the present invention is a following bellows compensator, which includes a working bellows 5, with a first connecting pipe 1 and a second connecting pipe 20 welded to the left and right ends of the working bellows respectively. A first ring plate 2 is welded to the first connecting pipe, a second ring plate 7 is welded to the second connecting pipe, and a third ring plate 10 is fitted onto the second connecting pipe. The left ends of a plurality of tie rods 4 are symmetrically connected to the first ring plate, and the right ends of the tie rods extend from the second ring plate and the third ring plate.

[0005] Its characteristic is that a balance bellows is sealed and welded between the second ring plate and the third ring plate. The balance bellows consists of an inner bellows 8' and an outer bellows 8. The inner bellows 8' and the outer bellows 8 form a cavity with an annular cross-section. This cavity is connected to the second connecting pipe through the guide pipe 6. The axial pressure-bearing cross-sectional area of ​​the balance bellows is equal to the axial pressure-bearing cross-sectional area of ​​the working bellows 5.

[0006] The right end of the pull rod is fixedly connected to a fourth ring plate 15. Multiple following devices are symmetrically arranged between the fourth ring plate and the third ring plate. The following device includes a rack 9 fixedly connected to the second ring plate 7. The rack 9 passes through the third ring plate 10 and meshes with a gear 12. The gear is connected to one end of a rotating shaft 13. The middle part of the rotating shaft is located in a cuboid bearing 16. The other end of the rotating shaft is connected to a cam 18. A disc spring 21 is provided between the cam and the bearing. A fastening nut 14 is screwed onto the rotating shaft. The fastening nut is in contact with the cam. The cam is in contact with a roller 17. The roller is sleeved on a pin 19. The pin is inserted into a cuboid horizontal bar 11. The horizontal bar 11 is fixedly connected to the third ring plate. The cuboid bearing 16 is fixedly connected to the fourth ring plate 15. When the gear rotates, the second ring plate and the third ring plate move synchronously along the axial direction.

[0007] The invention is characterized by the use of a working bellows to compensate for the displacement of the pipeline, and a balancing bellows to balance the thrust in the compensator. When the pipeline expands or contracts due to heat, the balancing bellows can move synchronously with the pipeline. During the compensation process, only the length of the working bellows changes, while the length of the balancing bellows remains unchanged.

[0008] Its beneficial effects are that, since the axial pressure cross-sectional area of ​​the working bellows and the balancing bellows are equal, the length of the balancing bellows does not need to be equal to that of the working bellows, and the length of the balancing bellows can be reduced as much as possible, while only one working bellows is needed, which helps to reduce production costs; at the same time, it also reduces the length of the compensator, making it convenient for transportation and installation. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the structure of the present invention.

[0010] Figure 2 for Figure 1 A magnified view of section C.

[0011] Figure 3 for Figure 2 A-direction view.

[0012] Attached diagram symbols: 1-First connecting pipe, 2-First ring plate, 3-Adjusting nut, 4-Pull rod, 5-Working bellows, 6-Guide pipe, 7-Second ring plate, 8-Outer bellows, 8'-Inner bellows, 9-Rack, 10-Third ring plate, 11-Horizontal bar, 12-Gear, 13-Shaft, 14-Flange, 15-Fourth ring plate, 16-Shaft seat, 17-Pin, 18-Cam, 20-Second connecting pipe, 21-Butterfly spring, 23-Flat pin. Implementation

[0013] A follower-type bellows compensator includes a working bellows 5, with a first connecting pipe 1 and a second connecting pipe 20 welded to its left and right ends respectively. A first ring plate 2 is welded to the first connecting pipe, a second ring plate 7 is welded to the second connecting pipe, and a third ring plate 10 is fitted onto the second connecting pipe. The left ends of a plurality of tie rods 4 are symmetrically inserted into the first ring plate, with the number of tie rods being 8 to 16. Adjusting nuts 3 are screwed onto the tie rods, which are located on both sides of the first ring plate and are tightly attached to the first ring plate. The right ends of the tie rods extend out from the second and third ring plates.

[0014] A balancing bellows is sealed and welded between the second ring plate 7 and the third ring plate 10. The balancing bellows consists of an inner bellows 8' and an outer bellows 8, which together form a cavity with an annular cross-section. This cavity is connected to the second connecting pipe via a guide pipe 6. The axial pressure-bearing cross-sectional area of ​​the balancing bellows is equal to that of the working bellows, thus ensuring that the thrust generated by the fluid medium in the balancing bellows and the working bellows is equal. The axial pressure-bearing cross-sectional area of ​​the balancing bellows is related to the inner bellows 8' and the outer bellows 8. When the diameter of the inner bellows 8' remains constant, an increase in the diameter of the outer bellows 8 will also increase the axial pressure-bearing cross-sectional area of ​​the balancing bellows.

[0015] A fourth ring plate 15 is fixedly connected to the right end of the pull rod. Four to eight following devices are symmetrically arranged between the fourth ring plate and the third ring plate. Each following device includes a rack 9 fixedly connected to the second ring plate 7. The rack 9 passes through the third ring plate 10 and meshes with a gear 12. The gear is connected to one end of a rotating shaft 13. The middle part of the rotating shaft is located in a cuboid bearing 16. A cam 18 is connected to the other end of the rotating shaft. A disc spring 21 is provided between the cam and the bearing 16. A fastening nut 14 is screwed onto the rotating shaft. Adjusting the fastening nut can adjust the friction between the cam and the bearing 16. The cam is in contact with the roller 17, the roller is sleeved on the pin 19, the pin is inserted into the rectangular crossbar 11, the crossbar 11 is fixedly connected to the third ring plate, and the rectangular shaft seat 16 is fixedly connected to the fourth ring plate 15. A flat key 23 is provided between the cam and the gear and the rotating shaft respectively; the line connecting the center of the pin and the center of the rotating shaft is parallel to the axis of the second pipe. When the rack translates, the gear and the cam rotate synchronously. By selecting the module and number of teeth of the gear and the curve of the cam, the second ring plate and the third ring plate can move synchronously along the axial direction (the axis of the second pipe) when the gear rotates.

[0016] The relationship between the radius of the cam and the gear rotation angle is as follows:

[0017] r = R + 0.008727mzα;

[0018] In the above formula, r is the radius of the cam, i.e. the distance between the cam profile and the shaft, R is the minimum radius of the cam profile, α is the rotation angle of the gear (in degrees), m is the gear module, and z is the number of gear teeth.

[0019] The gear module m is selected as 2, and the number of gear teeth z is selected as 12.

[0020] When the gear rotation angle increment is Δα, the rack displacement increment ΔL is equal to the cam profile radius increment Δr.

[0021] The difference between the minimum and maximum radii of the cam profile is greater than the expansion and contraction of the bellows.

[0022] The thrust balancing principle is that the distance between the first ring plate and the fourth ring plate is fixed. The working bellows and the balancing bellows are connected in series. The balancing bellows is connected to the fourth ring plate through a following device. That is, the balancing bellows is connected to the fourth ring plate through a crossbar, pin, roller, cam, rotating shaft and bearing. When the cam does not rotate, the distance between the third ring plate and the fourth ring plate will not change. The pressure of the fluid medium in the pipeline creates thrust in the working bellows and the balancing bellows. The thrust of the balancing bellows causes the roller to be in close contact with the cam. The thrust of the working bellows is applied to the cam through roller 17. The thrust of the working bellows on the cam can be decomposed into normal and tangential components. The tangential component is much smaller than the thrust. The normal component will not cause the cam to rotate, while the tangential component will cause the cam to rotate. The friction generated by the disc spring prevents the cam from rotating. When the friction generated by the disc spring is greater than or equal to the tangential component, the cam will not rotate, and the distance between the third and fourth ring plates will not change. Since the axial pressure cross-sectional areas of the working bellows and the balancing bellows are equal, the thrust generated by the fluid medium on the working bellows and the balancing bellows is equal in magnitude but opposite in direction, thereby achieving thrust compensation, that is, the compensator has no thrust output.

[0023] The aforementioned tangential component is related to the minimum radius R of the cam. When the thrust is constant, the larger the minimum radius R is, the smaller the tangential component is. The minimum radius R is greater than the radius of the working bellows. Therefore, the minimum radius R of the cam is selected to be 1.5 times the radius of the working bellows.

[0024] The principle of thermal expansion and contraction compensation in pipelines;

[0025] When the pipe contracts due to cold, it can be considered that an external force is applied to the first and second connecting pipes, causing the working bellows to be stretched. The second ring plate, which is fixedly connected to the working bellows, moves to the right. The rack on the fixed second ring plate drives the gear to rotate. The gear drives the cam to rotate clockwise through the rotating shaft. The roller moves towards the rotating shaft, and the balance bellows moves to the right. That is, the third ring plate also moves to the right and moves to the right synchronously with the second ring plate. The length of the balance bellows does not change. During the rightward movement, the roller and the cam are always in contact. In this way, the thrust on the working bellows and the balance bellows can still cancel each other out.

[0026] When the pipe expands due to heat, the working bellows is compressed, and the second ring plate, which is fixedly connected to the working bellows, moves to the left. The rack on the fixed second ring plate drives the gear to rotate counterclockwise. The gear drives the cam to rotate through the shaft, and the roller moves away from the shaft. The balance bellows moves to the left, and the third ring plate also moves to the right and moves to the left synchronously with the second ring plate. The length of the balance bellows does not change. During the leftward movement, the roller and the cam groove are always in contact, so the thrust on the working bellows and the balance bellows can still cancel each other out.

Claims

1. A follow-type bellows compensator, comprising a working bellows (5), with a first connecting pipe (1) and a second connecting pipe (20) welded to the left and right ends of the working bellows respectively, a first ring plate (2) welded to the first connecting pipe, a second ring plate (7) welded to the second connecting pipe, a third ring plate (10) fitted onto the second connecting pipe, and the left ends of multiple tie rods (4) symmetrically connected to the first ring plate, with the right ends of the tie rods extending from the second and third ring plates; Its characteristics are, A balance bellows is sealed between the second ring plate and the third ring plate. The balance bellows consists of an inner bellows (8') and an outer bellows (8). The inner bellows (8') and the outer bellows (8) form a cavity with an annular cross-section. The cavity is connected to the second connecting pipe through a guide pipe (6). The axial pressure cross-sectional area of ​​the balance bellows is equal to the axial pressure cross-sectional area of ​​the working bellows (5). The right end of the pull rod is fixedly connected to a fourth ring plate (15). Multiple following devices are symmetrically arranged between the fourth ring plate and the third ring plate. The following device includes a rack (9) fixedly connected to the second ring plate (7). The rack passes through the third ring plate (10) and meshes with a gear (12). The gear is connected to one end of a rotating shaft (13). The middle part of the rotating shaft is located in a cuboid-shaped bearing seat (16). The other end of the rotating shaft is connected to a cam (18). A disc spring (21) is provided between the cam and the bearing seat. A fastening nut (14) is screwed onto the rotating shaft. The fastening nut is in contact with the cam. The cam is in contact with the roller (17). The roller is sleeved on a pin (19). The pin is inserted into a cuboid-shaped horizontal bar (11). The horizontal bar is fixedly connected to the third ring plate. The bearing seat (16) is fixedly connected to the fourth ring plate (15). When the gear rotates, the second ring plate and the third ring plate move synchronously along the axial direction.

2. The following bellows compensator according to claim 1, characterized in that, The relationship between the radius of the cam and the gear rotation angle is as follows: r = R + 0.008727mzα; In the formula, r is the radius of the cam, i.e. the distance between the cam profile and the shaft, R is the minimum radius of the cam, α is the rotation angle of the gear in degrees, m is the gear module, and z is the number of gear teeth.

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