A special GIL double-bar link four-bar metal bellows compensator

Abstract

The present invention provides a special double-bar four-link metal bellows compensator for GIL, which includes two bellows, an airtight flange at the outer end of the first bellows, an airtight flange at the outer end of the second bellows, an intermediate connecting cylinder assembly arranged between the two bellows, as well as a double four-link mechanism assembly arranged on the outer periphery of the two bellows, and a limit tie rod and a guide bushing assembly. Compared with the prior art, the bellows compensator of the present invention, when meeting large displacement compensation, in order to overcome the excessive axial non-uniform deformation, non-axial deformation, and reduced column instability caused by the increase in the number of bellows or the number of waves, specifically adds two sets of symmetrically arranged double four-link mechanism assemblies to synchronize the axial expansion and contraction of the double bellows, and the deformation of the bellows is uniform; at the same time, it also specifically adds four sets of limit tie rod assemblies with bushings arranged circumferentially and uniformly to stabilize the axial expansion and contraction of the bellows and reduce the non-axial displacement stress of the bellows.

Description

Technical Field

[0001] The present invention belongs to the field of electric power, and particularly relates to a metal bellows compensator for a gas pipeline bus, which is mainly used for compensating large axial displacements on a long-distance GIL transmission line. Background Art

[0002] In the electric power industry, a rigid gas-insulated transmission line (GIL) is a power transmission device composed of a central conductor that provides a current path by enclosing an insulating gas with a certain pressure inside a metal pipe, and other insulating components.

[0003] As a large-capacity, high-voltage, long-distance power transmission line, GIL has the following characteristics:

[0004] 1. High reliability and long service life. GIL is a metal rigid enclosed structure, less affected by the external atmosphere and environment, and there is no external magnetic field influence. Inside, it uses SF6 or a mixture of SF6 and N2 gases, with good insulation performance, low dielectric loss, no aging problems, no flammability, and extremely high reliability. The average service life of GIL is more than 40 years;

[0005] 2. Strong transmission capacity. According to current technology, the transmission power of GIL can reach 4GW, with strong power transmission ability. It is beneficial to reduce the number of transmission circuits. Adopting a compact enclosed structure, it occupies less land than overhead lines. The layout method is flexible, which can simplify the system wiring and improve the power supply reliability of the entire system;

[0006] 3. The length of the GIL project is relatively long, generally more than 2 km. Due to the long length of GIL, large displacements will be generated due to thermal expansion and contraction.

[0007] Currently, for the bellows compensator used in the long-distance GIL transmission line, two bellows are combined to compensate for the large displacements generated by the long-distance line. The existing bellows compensator has the following defects:

[0008] 1) It cannot meet the large displacement compensation generated by the thermal expansion and contraction of the long-distance GIL line, such as an annual variation of ±130 mm and a service life of 120 times; a daily variation of ±70 and a service life of 22,000 times (60 years).

[0009] If the number of bellows waves is simply increased to increase the displacement compensation amount, the stability and service life of the bellows will be reduced.

[0010] 2) Under the action of axial external force, the two bellows in the bellows assembly of the compound bellows cannot stably expand and contract synchronously. There may be uneven local stress on the bellows, asynchronous expansion and contraction deformation amounts, and reduced service life.

[0011] 3) The existing bellows service life can only meet the requirement of 40 years and cannot meet the requirement of 60-year service life. Summary of the Invention

[0012] The present invention provides an installation device for a gas pipeline busbar that is flexibly and conveniently installed and has higher reliability. Specifically, it is a special double-link four-bar metal bellows compensator for GIL, which includes 2 bellows. Its characteristics are: it also includes a gas-tight flange at the outer end of the first bellows, a gas-tight flange at the outer end of the second bellows, an intermediate connection cylinder assembly arranged between the 2 bellows, and a double-link four-bar mechanism assembly, a limit tie rod and a guide bushing assembly arranged on the outer periphery of the 2 bellows.

[0013] Further, the gas-tight flange at the outer end of the first bellows is provided with 4 tie rod fixing holes.

[0014] Further, the gas-tight flange at the outer end of the second bellows is provided with 4 bushing guide holes.

[0015] Further, 4 bushing guide seats are provided on the outer periphery of the intermediate connection cylinder assembly.

[0016] Further, the double-link four-bar mechanism assembly includes a mechanism in the form of a double-rhombus double symmetry composed of 2 long connecting plates and 4 short connecting plates.

[0017] Further, 2 groups of the double-link four-bar mechanism assembly are symmetrically arranged on the outer side of the bellows.

[0018] Further, the limit tie rod and guide bushing assembly includes a limit tie rod, a guide bushing, a first limit nut, a second limit nut and a fastening nut. The limit tie rod and guide bushing assembly is 4 groups.

[0019] Advantages of the present invention:

[0020] 1) Compared with the prior art, in the aspect of GIL transmission lines, the bellows compensator of the present invention solves the problem of large-displacement telescopic compensation for long-distance GIL lines;

[0021] 2) In order to overcome the excessive axial non-uniform deformation, non-axial deformation, and reduced column instability stability caused by the increase in the number or number of waves of the bellows under the condition of satisfying large-displacement compensation, 2 groups of symmetrically arranged double-link four-bar mechanism assemblies are specially added to synchronously expand and contract the axially of the double bellows, and the bellows deformation is uniform; at the same time, 4 groups of circumferentially uniformly arranged limit tie rod assemblies with bushings are also specially added to stabilize the axial expansion and contraction of the bellows, reduce the non-axial displacement stress of the bellows, and greatly increase the column instability stability of the bellows, so as to meet the harsh requirements of customers for the high life of the bellows.

[0022] 3) The life of the bellows is increased from 40 years to 60 years, that is, the number of fatigue life cycles is increased from 15,000 times to 22,000 times. Brief Description of the Drawings

[0023] Figure 1 is the structural schematic diagram of the present invention;

[0024] Figure 2 is Figure 1 the A-A schematic diagram of

[0025] Figure 3 is Figure 1 the B-B schematic diagram of , that is, the cross-sectional view of the intermediate connecting cylinder assembly. Specific embodiments

[0026] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0027] The technical solution of the present invention is as follows:

[0028] 1. Structural design

[0029] The bellows compensator of the present invention mainly includes

[0030] 1) 2 bellows that meet the large displacement requirements;

[0031] 2) 1 first bellows outer end airtight flange with 4 pull rod fixing holes;

[0032] 3) 1 second bellows outer end airtight flange with 4 bushing guiding holes;

[0033] 4) 1 bellows intermediate connecting cylinder assembly, with 4 bushing guiding seats on its outer periphery;

[0034] 5) 2 sets of compound four-link mechanism assemblies;

[0035] 6) 4 sets of limit pull rod and guiding bushing assemblies.

[0036] Among them,

[0037] 1) One end of each bellows is connected to the outer end airtight flange, and the other end is connected to the intermediate connecting cylinder assembly;

[0038] 2) The pull rod is in shaft hole fit with the guiding bushing, and the relative displacement between the two is restricted by the limit nuts on both sides of the bushing. One end of the pull rod is fixed to the first bellows outer end airtight flange with pull rod fixing holes through a nut. The guiding bushing is in fit with the bushing guiding seat on the outer periphery of the intermediate connecting cylinder assembly, and the bushing can move axially in the bushing guiding seat; at the same time, the guiding bushing is in shaft hole fit with the second bellows outer end airtight flange with bushing guiding holes, and the bushing can move axially in the flange guiding hole;

[0039] 3) The double-diamond four-bar linkage mechanism is a double-diamond compound symmetric mechanism composed of two long connecting plates and four short connecting plates, which is arranged on the symmetric sides of two bellows and the intermediate connecting cylinder. For each side, the central hinge point of the mechanism formed by the intersection of the two long connecting plates is connected to the outer peripheral flange end face of the intermediate connecting cylinder through a pin shaft. The end hinge point formed by the intersection of the two short connecting plates is connected to the outer end airtight flange of the first bellows with a tie rod fixing hole through a pin shaft. The end hinge point formed by the intersection of the other two short connecting plates is connected to the outer end airtight flange of the second bellows with a bushing guiding hole through a pin shaft. The four hinge points formed by the intersection of the other two long connecting plates and the four short connecting plates are also connected through pin shafts.

[0040] As Figures 1 to 3 shown in an embodiment, the bellows compensator structure of the present invention mainly includes two bellows 1-1 and 1-2 that meet the large displacement requirements. The outer ends of the bellows are respectively connected to the outer end airtight flange 2 of the first bellows (with four tie rod fixing holes) and the outer end airtight flange 3 of the second bellows (with four bushing guiding holes). L0 is the initial distance between the compensator flange 2 and the flange 3 (the flange distance will change with the axial displacement compensation). The inner ends of the two bellows are respectively connected to the intermediate connecting cylinder assembly 4 (with four bushing guiding seats on the outer periphery) as a whole.

[0041] The double-diamond four-bar linkage mechanism 5 is a double-diamond compound symmetric mechanism composed of two long connecting plates and four short connecting plates. Two sets of double-diamond four-bar linkage mechanism components 5 composed of four-bar linkages are added on the symmetric sides of the bellows 1-1, 1-2 and the intermediate connecting cylinder assembly 4. It is composed of two long connecting plates 5-2 that are cross-hinged at the center point P0 and connected to the middle of the intermediate connecting cylinder assembly 4 through a pin shaft. One end of the two short connecting plates 5-1 is hinged, and there are two sets in total, which are respectively connected to the outer end airtight flange 2 of the first bellows and the outer end airtight flange 3 of the second bellows through a pin shaft at points P1 and P2. At the same time, the other ends, there are two sets in total, are hinged to the two long connecting plates 5-2 through a pin shaft at four symmetric side hinge points P3, P4, P5, and P6.

[0042] Four sets of limit tie rods and guiding bushing assemblies 6 are added to the outer periphery of the outer end airtight flange 2 of the first bellows, the outer end airtight flange 3 of the second bellows, and the intermediate connecting cylinder assembly 4.

[0043] The limiting tie rod and guide bushing assembly 6 includes a limiting tie rod 6-5, a guide bushing 6-2, a first limiting nut 6-1, a second limiting nut 6-3, and a fastening nut 6-4. The limiting tie rod 6-5 is in shaft hole fit with the guide bushing 6-2, and the relative displacement between the two is restricted by the limiting nuts 6-1 and 6-3 on both sides of the guide bushing 6-2. One end of the tie rod 6-5 is fixed to the outer end airtight flange 2 of the first bellows with a tie rod fixing hole through the fastening nut 6-4. The guide bushing 6-2 is in fit with the bushing guide seat 4-1 on the outer periphery of the intermediate connecting cylinder assembly 4, and the guide bushing 6-2 can axially move within the bushing guide seat 4-1. At the same time, the tie rod guide bushing 6-2 is in shaft hole fit with the outer end airtight flange 3 of the second bellows with a bushing guide hole, and the bushing 6-2 can axially move within the guide hole of the flange 3.

[0044] 2. Functional analysis

[0045] 1) Design for the large displacement requirement of the bellows. According to the standards JB / T 10617-2006 Metal Bellows Compensator for High-Voltage Composite Electrical Apparatus, GB / T 12777-2008 General Technical Conditions for Metal Bellows Expansion Joints, GB / T 16749-2018 Pressure Vessel Corrugated Expansion Joints, etc., the bellows of the bellows compensator of the present invention that meets the large displacement requirement is calculated.

[0046] For example, the annual change is ±130 mm and the service life is 120 times; the daily change is ±70 mm and the service life is 22,000 times. According to the standard, a compound large displacement bellows that meets the large displacement requirement is designed.

[0047] 2) Add 4 groups of circumferentially evenly distributed limiting tie rod sliding sleeve assemblies 6 on the basis of the compound large displacement bellows compensator to play a role in stable guiding and limiting. In this way, the bellows can perform stable axial telescopic displacement under the action of axial external force, thus avoiding the shortening of the bellows life caused by the increase of non-axial displacement stress caused by the self-weight of the bellows compensator in the case of large displacement. In addition, according to the design displacement requirement, the limiting nuts 6-1 and 6-3 on the limiting tie rod sliding sleeve assembly 6 adjust and limit the stroke of the guide bushing 6-2 to meet the setting of the maximum displacement of the bellows and enable the distance to the airtight flange 3 to be adjusted.

[0048] 3) On top of the above, add another 2 sets of symmetrically arranged compound four-bar linkage mechanism components 5. When the bellows compensator undergoes displacement under the action of an axial external force, the compound four-bar linkage mechanism will move synchronously, playing a role of synchronous linkage. When the bellows 1-1 and 1-2 are subjected to unbalanced forces or displacements, due to the specific motion trajectory factors of the four-bar linkage mechanism 5, that is, the axial displacement amounts on both sides of the central hinge point P0 of the long connecting plate are equal and synchronous. In this way, the total displacement change amount 2L of the compound large-displacement bellows compensator will be evenly distributed to the 2 bellows, and the displacements L on each bellows are equal and synchronous in linkage, thereby avoiding the possibility that the life of a certain bellows is shortened due to excessive local stress and deformation during expansion and contraction.

[0049] 4) Assume that the airtight flange 3 on the bellows compensator is constrained and immovable, and the airtight flange 2 is subjected to an axial external force. The bellows 1-1 and 1-2 will be compressed or elongated. Due to the specific motion trajectory factors of the four-bar linkage mechanism, the bellows 1-1 and 1-2 will be forced to move synchronously in linkage. Also, due to the constraint of the limit nut on the limit pull rod sliding sleeve assembly 6, the displacement amount of each single bellows is L, and the total displacement amount is 2L.

[0050] For example Figure 1 、 2 in, taking the annual change amount of ±130mm, then the total displacement change amount of the bellows compensator 2*2L = 260mm, the total displacement change amount of each single bellows 2*L = 130mm, L = 65mm; taking the daily change amount of ±70mm, then 2*2L = 140mm, the total displacement change amount of each single bellows 2*L = 70mm, L = 35mm. Taking the maximum value of L = 65mm, adjust and limit the stroke of the sliding sleeve to meet the setting of the maximum displacement amount of the bellows.

[0051] The key points of the bellows compensator of the present invention:

[0052] 1) The bellows compensates for large displacement expansion and contraction amounts;

[0053] 2) The compound four-bar linkage mechanism components synchronously expand and contract the double bellows;

[0054] 3) The limit pull rod assembly with a bushing stabilizes the axial expansion and contraction of the bellows.

[0055] Combined with the above key points, the GIL special bellows compensator can improve the service life of the compensator and maintain synchronous and stable expansion and contraction under large displacement working conditions.

[0056] The above is the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A special double-rod four-link metal bellows compensator for GIL, comprising two bellows, characterized in that: It also includes an airtight flange at the outer end of the first bellows, an airtight flange at the outer end of the second bellows, an intermediate connecting cylinder assembly arranged between the two bellows, a compound four-bar linkage assembly arranged on the outer periphery of the two bellows, a limit pull rod and a guide bushing assembly; the compound four-bar linkage assembly is symmetrically arranged in two groups on the outer side of the bellows. Each group of the compound four-bar linkage includes two long connecting plates and four short connecting plates. The mechanism center hinge point formed by the intersection of the two long connecting plates is connected to the outer peripheral flange end face of the intermediate connecting cylinder through a pin shaft. The end hinge point formed by the intersection of the two short connecting plates is connected to the airtight flange at the outer end of the first bellows with a pull rod fixing hole through a pin shaft. The end hinge point formed by the intersection of the other two short connecting plates is connected to the airtight flange at the outer end of the second bellows with a bushing guiding hole through a pin shaft. And the compound four-bar linkage assembly is used for synchronously axially expanding and contracting the double bellows, and the bellows deforms evenly. Four groups of limit pull rods and guide bushing assemblies are additionally arranged on the outer periphery of the airtight flange at the outer end of the first bellows, the airtight flange at the outer end of the second bellows, and the intermediate connecting cylinder assembly; the limit pull rod and guide bushing assembly includes a limit pull rod, a guide bushing, a first limit nut, a second limit nut and a fastening nut; wherein, the limit pull rod is in shaft hole fit with the guide bushing, and the relative displacement between the two is restricted by the limit nuts on both sides of the guide bushing. One end of the pull rod is fixed to the airtight flange at the outer end of the first bellows with a pull rod fixing hole through a fastening nut. The guide bushing is in fit with the bushing guiding seat on the outer periphery of the intermediate connecting cylinder assembly, and the guide bushing can axially move in the bushing guiding seat; at the same time, the pull rod guide bushing is in shaft hole fit with the bushing guiding hole on the airtight flange at the outer end of the second bellows, and the bushing can axially move in the flange guiding hole.

2. The metal bellows compensator according to claim 1, wherein: The airtight flange at the outer end of the first bellows is provided with four pull rod fixing holes.

3. The metal bellows compensator according to claim 1 or 2, characterized in that: The airtight flange at the outer end of the second bellows is provided with four bushing guiding holes.

4. The metal bellows compensator according to claim 1, wherein: Four bushing guiding seats are provided on the outer periphery of the intermediate connecting cylinder assembly.

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