Large transformer bushing anti-seismic connecting structure

Abstract

The embodiment of the application relates to the technical field of power transformer anti-seismic protection, in particular to a large transformer bushing anti-seismic connecting structure, which comprises a bushing flange, an upper connecting plate, an annular anti-seismic rubber support, a lower connecting plate, a whole annular limiting anti-pulling base and an annular buffer sealing piece. The anti-seismic rubber support is arranged between the upper and lower connecting plates, and the three are provided with central through holes through which power components pass. The anti-pulling base surrounds the outer periphery of the support and is fixed to the raised base, the inner periphery surface of the anti-pulling base is provided with a limiting groove, the buffer sealing piece is arranged on the outer periphery of the upper connecting plate and extends into the limiting groove, and a radial movable gap and an axial limiting gap are arranged between the two. The anti-seismic rubber support is used for generating shear deformation and consuming energy when horizontal relative motion occurs. The application realizes the effects of reducing stress concentration at the root of the bushing, improving energy consumption and displacement adaptation capacity by coupling the support and the anti-pulling base.

Description

Technical Field

[0001] This application relates to the field of seismic protection technology for power transformers, and in particular to a seismic connection structure for bushings of large transformers. Background Technology

[0002] Large transformers are prone to increased relative motion between the transformer body and bushings under strong earthquakes, stress concentration at the bushing root, and cracking or damage to the porcelain or composite external insulation. In severe cases, this can lead to grounding short circuits, insulating oil leaks, and power outages. Existing technologies have the following main shortcomings: the seismic performance of transformer bushings is tested or analyzed according to relevant standards to verify their mechanical and electrical performance during and after a specified earthquake input. Various tests show that the overall dynamic characteristics of the bushing and its installation connection structure have a significant impact on the stress response of key bushing sections. Installing lead-core rubber supports, unbonded annular rubber isolation devices, or friction pendulums at the bottom of the transformer body can reduce the seismic acceleration response of the transformer body, but it is difficult to simultaneously address the dynamic response corresponding to higher-order bending modes of the bushing. When the transformer body uses seismic isolation measures, but the bushing is still connected to the riser via rigid flange bolts, the relative displacement and sudden changes in local stiffness at the connection point can still lead to increased stress at the bushing root. Currently, the bushing flange and riser are usually directly connected using rigid bolts. Under seismic loading, the rotation and bending moments generated at the connection points are easily transmitted directly to the casing root. Furthermore, the energy dissipation and displacement adaptability of this connection method are limited, which may lead to an increase in the dynamic response at the casing root.

[0003] Therefore, it is necessary to provide a seismic connection structure that, without affecting the electrical connection and sealing performance of the bushing, enables the connection interface between the bushing flange and the riser to have controllable horizontal stiffness, damping, and displacement adaptability. Summary of the Invention

[0004] To address this, the present invention provides a seismic-resistant connection structure for large transformer bushings, which overcomes the problems of insufficient energy dissipation capacity and excessive bending moment and stress concentration at the bushing root under seismic action in the existing rigid connection method.

[0005] To achieve the above objectives, the present invention provides a seismic-resistant connection structure for large transformer bushings. It includes:

[0006] Sleeve flange, upper connecting plate, annular anti-seismic rubber bearing, lower connecting plate, integral annular limiting anti-pull-out seat and annular buffer seal;

[0007] The sleeve flange is fixedly connected to the upper connecting plate, and the annular anti-seismic rubber support is disposed between the upper connecting plate and the lower connecting plate. The annular anti-seismic rubber support, the upper connecting plate and the lower connecting plate all have a central through hole for the conductive components inside the sleeve to pass through.

[0008] The integral annular limiting anti-pull-out seat is arranged around the outer periphery of the annular anti-seismic rubber bearing and is fixed to the lifting seat by a plurality of mounting bolts arranged at intervals along the circumference.

[0009] The inner circumferential surface of the integral annular limiting anti-pull-out seat is provided with an annular limiting groove facing the opening of the upper connecting plate, and the annular buffer seal is provided on the outer circumference of the upper connecting plate and extends into the annular limiting groove.

[0010] A radial movable gap is provided between the annular buffer seal and the annular limiting groove to allow the upper connecting plate to move horizontally relative to the lifting seat, and an axial limiting gap is provided. The axial limiting gap is used to allow the upper connecting plate to generate axial displacement relative to the lifting seat. When the axial displacement reaches the limit value of the axial limiting gap, the integral annular limiting anti-pull-out seat abuts against the annular buffer seal to withstand the vertical load and provide anti-pull-out limiting.

[0011] The annular anti-seismic rubber bearing is used to generate elastic deformation and dissipate vibration energy when the riser and the sleeve flange move relative to each other. The elastic deformation includes at least horizontal shear deformation.

[0012] Furthermore, the integral annular limiting anti-pull-out seat includes an annular mounting part, an annular sidewall extending upward from the annular mounting part, and an annular limiting part extending inward from the upper end of the annular sidewall.

[0013] The annular limiting part and the annular sidewall together define the annular limiting groove, and the opening of the annular limiting groove is open towards the upper connecting plate;

[0014] The annular mounting portion is supported on the top flange of the riser, and a plurality of mounting bolts are evenly distributed around the circumference of the annular mounting portion, thereby detachably connecting the annular mounting portion to the top flange of the riser.

[0015] Furthermore, the annular buffer seal includes an annular connecting portion connected to the outer periphery of the upper connecting plate and an annular mating portion extending into the annular limiting groove;

[0016] The shape of the annular mating part is adapted to the groove shape of the annular limiting groove, and the radial thickness of the annular mating part is less than the radial width of the annular limiting groove to form the radial movable gap.

[0017] The annular buffer seal is made of oil-resistant elastic material. When the horizontal displacement of the sleeve flange relative to the riser reaches a preset limit, the annular buffer seal contacts the side wall of the annular limiting groove to limit the maximum horizontal displacement of the sleeve flange and buffer the contact impact.

[0018] Furthermore, the axial limiting gap is the vertical distance between the upper wall of the annular limiting groove and the upper surface of the annular buffer seal; when the axial displacement of the sleeve flange relative to the riser seat reaches the limit value of the axial limiting gap, the upper surface of the annular buffer seal abuts against the upper wall of the annular limiting groove to restrict the vertical separation between the sleeve flange and the riser seat.

[0019] The integral annular limiting anti-pull-out seat abuts against the annular buffer seal through the annular limiting part to transmit vertical pull-out force, so that the integral annular limiting anti-pull-out seat can simultaneously perform the function of anti-pull-out limiting.

[0020] Furthermore, the annular anti-seismic rubber bearing includes multiple layers of rubber and multiple layers of steel plates that are alternately arranged along the axial direction and vulcanized together;

[0021] The upper end of the annular anti-seismic rubber bearing is vulcanized to the lower surface of the upper connecting plate, and the lower end is vulcanized to the upper surface of the lower connecting plate.

[0022] The annular seismic rubber bearing forms a force transmission path with the sleeve flange and the riser seat through the upper connecting plate and the lower connecting plate, respectively.

[0023] Furthermore, the annular anti-seismic rubber bearing is provided with multiple lead cores spaced apart along the circumference;

[0024] Each of the lead cores penetrates at least a portion of the rubber layer and the steel plate layer along the axial direction of the annular anti-seismic rubber bearing, and is vulcanized and connected to the rubber layer and the steel plate layer simultaneously;

[0025] The lead core is used to provide additional hysteretic energy dissipation through plastic deformation when the annular anti-seismic rubber bearing undergoes shear deformation.

[0026] Furthermore, the lower connecting plate is disposed on the top of the lifting seat, and the lower surface of the lower connecting plate is supported on the upper surface of the top flange of the lifting seat;

[0027] The annular mounting part of the integral annular limiting anti-pull-out seat is pressed onto the upper surface of the lower connecting plate, and the lower connecting plate is simultaneously pressed and fixed to the top flange of the lifting seat by the mounting bolts.

[0028] Furthermore, the radial movable gap is not less than the design shear displacement of the annular seismic rubber bearing;

[0029] The radial dimension of the annular limiting groove is configured such that, before the annular anti-seismic rubber bearing reaches the allowable shear displacement, the sidewall of the annular limiting groove and the annular buffer seal maintain the radial movement gap, without restricting the horizontal movement of the upper connecting plate; when the horizontal displacement reaches the limit value of the radial movement gap, the sidewall of the annular limiting groove abuts against the annular buffer seal to achieve horizontal limiting of the upper connecting plate.

[0030] Furthermore, the sleeve flange and the upper connecting plate are fixedly connected by a plurality of first fasteners distributed circumferentially at intervals;

[0031] An adjusting shim is provided between the upper surface of the upper connecting plate and the lower surface of the sleeve flange to compensate for the installation gap.

[0032] Furthermore, the central through hole of the annular anti-seismic rubber bearing, the central through hole of the upper connecting plate, and the central through hole of the lower connecting plate are coaxially arranged;

[0033] The inner diameter of the central through hole is larger than the maximum outer diameter of the conductive component inside the sleeve, so as to provide clearance space for the conductive component when the annular anti-seismic rubber bearing undergoes shear deformation.

[0034] Compared with the prior art, the beneficial effect of the present invention is that, in this embodiment, the integral annular limiting anti-pullback seat is set as an integrated structure composed of an annular mounting part, an annular sidewall, and an annular limiting part. The annular limiting part and the annular sidewall together define an annular limiting groove with its opening facing the upper connecting plate. This allows the annular buffer seal, under the cooperation of radial movement clearance and axial limiting clearance, to freely adapt to the horizontal displacement space required by the shear deformation of the seismic rubber bearing. Furthermore, when the displacement reaches the limit value, a reliable contact is formed between the lower surface of the annular limiting part and the inner surface of the annular sidewall with the annular buffer seal. It simultaneously achieves horizontal limiting and pull-out limiting functions, eliminating the need for separate pull-out and limiting components, thus simplifying the structural hierarchy and assembly process. The annular mounting part is directly and detachably connected to the top flange of the riser seat through circumferentially evenly distributed mounting bolts, which not only ensures the tight fixing of the lower connecting plate, but also facilitates installation during the renovation of existing transformers and subsequent maintenance and disassembly. At the same time, the integrated structure makes the overall stiffness of the limiting and pull-out seat uniform and the force path clear, avoiding the problems of eccentric load and stress concentration that may occur when the split structure is subjected to forces in multiple directions, effectively improving the load-bearing reliability and durability of the connection structure under strong earthquakes.

[0035] Furthermore, this embodiment sets the annular buffer seal as an integrated elastic component with an annular connecting part and an annular mating part. The annular mating part extends into the limiting groove with a radial thickness smaller than the radial width of the limiting groove to form a radially movable gap. This not only reserves sufficient space for the free shear deformation of the seismic rubber bearing under small and medium earthquakes, but also achieves the dual functions of rigid limiting and flexible buffering through the elastic contact between the annular mating part and the side wall of the limiting groove when the horizontal displacement reaches the preset limit under a major earthquake. Displacement constraint and collision buffering can be completed simultaneously without the need for additional independent limiting components, simplifying the structure and improving impact resistance reliability. At the same time, the use of oil-resistant elastic material for integrated molding allows the annular connecting part to form a reliable sealing interface with the outer peripheral wall of the upper connecting plate through an interference fit. Even when the shear deformation of the bearing causes relative displacement of the connection interface, the oil tightness can still be maintained. The three functions of limiting, buffering and sealing are integrated into the same component, reducing the number of seals and buffers, reducing assembly complexity, and improving the overall sealing safety margin of the connection structure under strong earthquakes.

[0036] Furthermore, this embodiment reserves an axial limiting gap between the upper wall of the annular limiting groove and the upper surface of the annular buffer seal, ensuring that the connection structure does not impose additional constraints on vertical deformation under normal working conditions. This ensures that the horizontal shear energy dissipation function of the seismic rubber bearing is not interfered with by the vertical limiting gap. At the same time, when the vertical displacement reaches the limit value, the surface contact between the upper surface of the annular buffer seal and the upper wall of the annular limiting groove achieves uniform pull-out force transmission throughout the circumference. The integrated structure of the integral annular limiting pull-out seat simultaneously undertakes the dual functions of horizontal limiting and pull-out limiting, eliminating the need for separate pull-out components. This simplifies the structural hierarchy and assembly process, while ensuring the uniformity and reliability of vertical load transmission under strong earthquakes, and avoiding the risk of off-center loading and local failure that may exist in split pull-out structures.

[0037] Furthermore, this embodiment sets the annular seismic rubber bearing as an integral structure with alternating vulcanized connections of multiple rubber layers and multiple steel plate layers. This allows the bearing to exhibit low shear stiffness in the horizontal direction for flexible seismic isolation and high compressive stiffness in the vertical direction for stable load bearing, achieving a decoupled design of horizontal flexible seismic isolation and reliable vertical support. The rubber layer uses high-damping material and dissipates vibration energy through hysteretic deformation during cyclic shearing, reducing the bending moment and stress transmitted to the root of the sleeve from the source. At the same time, the constraint effect of the multiple steel plate layers ensures the uniformity of shear deformation of the rubber layer and the overall stability of the bearing, effectively avoiding the overturning or instability problems that may occur with pure rubber bearings under large displacement shearing, and significantly improving the seismic isolation effect and durability of the connection structure under strong earthquakes.

[0038] Furthermore, this embodiment, by circumferentially spaced multiple lead cores within the annular seismic rubber bearing and simultaneously vulcanizing them with each rubber layer and steel plate layer, allows the lead cores to provide additional hysteretic energy dissipation through plastic deformation during shear deformation. This significantly improves the bearing's equivalent damping ratio and energy dissipation capacity, effectively suppressing the vibration response at the casing root under seismic loading. Simultaneously, the uniform circumferential distribution of the lead cores ensures consistent energy dissipation in all directions, avoiding energy dissipation blind spots caused by the uncertainty of earthquake direction. This overcomes the shortcomings of pure rubber bearings, such as low damping ratio and insufficient energy dissipation capacity, giving the bearing both the flexible seismic isolation performance of rubber and the high-efficiency energy dissipation performance of lead cores. In addition, the lead cores penetrate and connect each rubber layer and steel plate layer, and under normal conditions, they can also play a certain role in shear positioning, enhancing the coordinated deformation capacity between layers and improving the structural integrity and fatigue durability of the bearing under repeated seismic loading.

[0039] Furthermore, in this embodiment, the annular mounting part of the integral annular limiting anti-pullback seat is pressed onto the upper surface of the lower connecting plate, and the same set of mounting bolts is used to simultaneously press and fix the annular mounting part and the lower connecting plate to the top flange of the riser seat. This achieves reliable fixation between the lower connecting plate and the riser seat, eliminating the need for separate connecting parts for the lower connecting plate, reducing the number of bolts and assembly steps, and simplifying the connection structure hierarchy and installation process. At the same time, the overlapping structure allows the installation of the lower connecting plate and the limiting anti-pullback seat to be completed simultaneously, ensuring a uniform distribution of the surface contact clamping force between the lower connecting plate and the top flange of the riser seat. This avoids local warping or uneven stress that may occur due to separate fixation, thereby ensuring that the horizontal movement of the riser seat under seismic action can be uniformly transmitted to the lower end of the annular seismic rubber bearing through the lower connecting plate. This improves the reliability of force transmission and the uniformity of bearing shear deformation, and facilitates rapid installation and subsequent disassembly and maintenance during the retrofitting of existing transformers.

[0040] Furthermore, this embodiment sets the radial movable gap to be no less than the design shear displacement of the annular seismic rubber bearing, allowing the bearing to freely shear deform within the design earthquake range. This fully utilizes its flexible isolation and hysteretic energy dissipation functions without interference from the limiting components, avoiding premature limiting that could lead to a decrease in the bearing's isolation effect or a sudden increase in stiffness. Simultaneously, by rationally matching the radial dimensions of the annular limiting groove, the horizontal limiting is precisely triggered when the bearing reaches its allowable shear displacement. This protects the bearing from excessive shear failure and avoids impact damage to structural components from rigid collisions, significantly improving the adaptability and safety of the connection structure under different levels of seismic loading. In addition, the cooperation of the first fastener and the adjusting shim ensures reliable fixing and installation accuracy between the sleeve flange and the upper connecting plate, while also facilitating adjustments to the installation gap according to actual working conditions. This reduces the requirements for processing and assembly precision, improving the convenience and versatility of engineering implementation.

[0041] Furthermore, in this embodiment, the central through-holes of the annular seismic rubber bearing, the upper connecting plate, and the lower connecting plate are coaxially arranged, and the inner diameter of each central through-hole is larger than the maximum outer diameter of the conductive component inside the sleeve. A radial clearance not less than the design shear displacement of the bearing is reserved between the conductive component and the inner wall of the through-hole. This allows the conductive component to pass freely without contacting or interfering with the inner wall of the through-hole when the bearing undergoes horizontal shear deformation. This avoids the conductive component from bearing additional bending stress due to bearing deformation and prevents collision damage and insulation failure between the conductive component and the metal components, ensuring the safety and reliability of the electrical connection. At the same time, there is no mechanical coupling between the conductive component and the seismic isolation structure, realizing a complete decoupling design between the electrical path and the seismic isolation path. This allows them to work independently under seismic action without affecting each other, fundamentally solving the electrical insulation risk and additional stress problem caused by the deformation of the conductive component along with the connection structure in traditional rigid connections. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the seismic connection structure of the large transformer bushing according to an embodiment of this application;

[0043] Figure 2 This is a schematic diagram comparing the working principles of the rigid connection provided in the embodiments of this application and the seismic connection of the present invention;

[0044] In the diagram, 1-sleeve; 2-sleeve flange; 3-upper connecting plate; 4-annular anti-seismic rubber bearing; 5-lower connecting plate; 6-integral annular limit anti-pull-out seat; 7-annular buffer seal; 8-mounting bolt; 9-lift seat. Detailed Implementation

[0045] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0046] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0047] like Figures 1-2 As shown, Figure 1 This is a schematic diagram of the seismic connection structure of the large transformer bushing according to an embodiment of this application; Figure 2 This is a schematic diagram comparing the working principles of the rigid connection provided in the embodiments of this application and the seismic connection of the present invention.

[0048] The technical solutions provided in the embodiments of this application include:

[0049] 2. Sleeve flange; 3. Upper connecting plate; 4. Annular anti-seismic rubber bearing; 5. Lower connecting plate; 6. Integral annular limiting anti-pull-out seat; and 7. Annular buffer seal.

[0050] The sleeve flange 2 is fixedly connected to the upper connecting plate 3, and the annular anti-seismic rubber support 4 is disposed between the upper connecting plate 3 and the lower connecting plate 5. The annular anti-seismic rubber support 4, the upper connecting plate 3 and the lower connecting plate 5 all have a central through hole for the conductive components inside the sleeve 1 to pass through.

[0051] The integral annular limiting anti-pull-out seat 6 is arranged around the outer periphery of the annular anti-seismic rubber support 4 and is fixed to the lifting seat 9 by a plurality of mounting bolts 8 arranged at intervals along the circumference.

[0052] The inner circumferential surface of the integral annular limiting anti-pull-out seat 6 is provided with an annular limiting groove that opens toward the upper connecting plate 3, and the annular buffer seal 7 is disposed on the outer circumference of the upper connecting plate 3 and extends into the annular limiting groove.

[0053] A radial movable gap is provided between the annular buffer seal 7 and the annular limiting groove to allow the upper connecting plate 3 to move horizontally relative to the lifting seat 9, and an axial limiting gap is provided. The axial limiting gap is used to allow the upper connecting plate 3 to generate axial displacement relative to the lifting seat 9. When the axial displacement reaches the limit value of the axial limiting gap, the integral annular limiting anti-pull-out seat 6 abuts against the annular buffer seal 7 to withstand the vertical load and provide anti-pull-out limiting.

[0054] The annular anti-seismic rubber bearing 4 is used to generate elastic deformation and dissipate vibration energy when the riser 9 and the sleeve flange 2 move relative to each other. The elastic deformation includes at least horizontal shear deformation.

[0055] Specifically, the integral annular limiting anti-pull-out seat 6 includes an annular mounting part, an annular sidewall extending upward from the annular mounting part, and an annular limiting part extending inward from the upper end of the annular sidewall.

[0056] The annular limiting part and the annular sidewall together define the annular limiting groove, and the opening of the annular limiting groove is open towards the upper connecting plate 3;

[0057] The annular mounting portion is supported on the top flange of the riser 9, and a plurality of mounting bolts 8 are evenly distributed along the circumference of the annular mounting portion, thereby detachably connecting the annular mounting portion to the top flange of the riser 9.

[0058] In this embodiment, the annular mounting portion of the integral annular limiting anti-pull-out seat 6 has an annular flat plate structure, with its bottom surface abutting against the upper surface of the top flange of the riser seat 9, and is detachably fixed to the riser seat 9 by a plurality of mounting bolts 8 evenly distributed circumferentially. The annular sidewall extends vertically upward from near the inner edge of the annular mounting portion, and the annular limiting portion extends horizontally inward radially from the upper end of the annular sidewall, so that the cross-section of the annular limiting groove is an "L"-shaped or inverted "U"-shaped groove structure with the opening facing the inner upper side. The groove opening of the annular limiting groove is open towards the outer peripheral wall of the upper connecting plate 3 to accommodate at least a portion of the annular buffer seal 7. The lower surface of the annular limiting portion and the inner surface of the annular sidewall together define the upper wall and side wall of the annular limiting groove, which are used to form a contact fit with the annular buffer seal 7 when the upper connecting plate 3 undergoes horizontal displacement or vertical displacement reaching a preset limit value, thereby realizing the horizontal limiting and anti-pull-out limiting functions. The annular mounting part has a through hole for the bolt to pass through at the position where the mounting bolt 8 is located, and the top flange of the lifting seat 9 has a threaded hole at the corresponding position to facilitate installation, disassembly and maintenance.

[0059] Specifically, the annular limiting anti-pull-out seat 6 has multiple displacement monitoring units embedded in its annular sidewall, which are spaced apart along the circumference.

[0060] Each of the displacement monitoring units includes a fiber optic strain sensor, the sensing end of which extends into the inner surface of the side wall of the annular limiting groove, for real-time detection of the contact state and contact pressure value between the outer peripheral surface of the annular buffer seal 7 and the side wall of the annular limiting groove.

[0061] Each of the fiber optic strain sensors is led out along the bottom surface of the annular mounting part via fiber optic leads and connected to an external signal demodulator via the outer wall of the riser 9.

[0062] The external signal demodulator is used to convert the wavelength offset signals collected by each fiber optic strain sensor into contact pressure values, and to issue an alarm signal when any of the contact pressure values ​​exceeds a preset warning threshold.

[0063] In this embodiment, 8 to 16 fiber optic strain sensors are embedded at equal angular intervals along the circumferential direction within the annular sidewall of the integral annular limiting anti-pullback seat 6. Each sensor is pre-embedded inside the annular sidewall during casting or machining, with its sensing end flush with the inner surface of the annular limiting groove sidewall to ensure direct contact with the outer circumferential surface of the annular buffer seal 7. The fiber optic strain sensor features small size, resistance to electromagnetic interference, and passive sensing, making it particularly suitable for long-term online monitoring of transformers in strong electromagnetic field environments. All sensors are connected to a fiber optic hub via fiber optic leads, and then led to a signal demodulator in the external control room of the transformer via a main optical cable.

[0064] During normal operation, the annular buffer seal 7 remains in non-contact with the sidewall of the annular limiting groove, and the output signals of each sensor remain stable at the baseline value. When the horizontal displacement increases under seismic action and reaches a preset limit, the outer circumferential surface of the annular buffer seal 7 comes into contact with the sidewall of the annular limiting groove and applies pressure. The fiber optic strain sensor embedded in the sidewall senses this contact pressure in real time and outputs a corresponding signal. When any contact pressure value exceeds a preset warning threshold, the signal demodulator sends an alarm signal to the transformer control center, indicating to maintenance personnel that the connection structure has experienced over-limit displacement contact and is subjected to a large impact load, requiring post-earthquake inspection and maintenance. In addition, by comparing the signal distribution of each circumferential position sensor, the main direction of the seismic action and the degree of uneven loading in each direction can be determined, providing data support for post-earthquake structural damage assessment.

[0065] This embodiment sets the integral annular limiting anti-pullback seat as an integrated structure consisting of an annular mounting part, an annular sidewall, and an annular limiting part. The annular limiting part and the annular sidewall together define an annular limiting groove with its opening facing the upper connecting plate. This allows the annular buffer seal, with the cooperation of radial and axial limiting clearances, to freely adapt to the horizontal displacement space required by the shear deformation of the seismic rubber bearing. Furthermore, when the displacement reaches a limit, the lower surface of the annular limiting part and the inner surface of the annular sidewall form a reliable contact fit with the annular buffer seal, simultaneously achieving horizontal limiting. With its pull-out limiting function, it eliminates the need for separate pull-out and limiting components, simplifying the structural layers and assembly process. The annular mounting part is directly and detachably connected to the top flange of the riser seat via circumferentially evenly distributed mounting bolts. This ensures the tight fixing of the lower connecting plate and facilitates installation during the renovation of existing transformers and subsequent maintenance and disassembly. At the same time, the integrated structure makes the overall stiffness of the limiting pull-out seat uniform and the force path clear, avoiding the problems of eccentric load and stress concentration that may occur when the split structure is subjected to forces in multiple directions. This effectively improves the load-bearing reliability and durability of the connection structure under strong earthquakes.

[0066] Specifically, the axial limiting gap is the vertical distance between the upper wall of the annular limiting groove and the upper surface of the annular buffer seal 7;

[0067] When the axial displacement of the sleeve flange 2 relative to the riser seat reaches the limit value of the axial limiting gap, the upper surface of the annular buffer seal 7 abuts against the upper wall of the annular limiting groove to restrict the vertical separation between the sleeve flange and the riser seat 9.

[0068] The integral annular limiting anti-pull-out seat abuts against the annular buffer seal 7 through the annular limiting part to transmit vertical pulling force, so that the integral annular limiting anti-pull-out seat can simultaneously undertake the function of anti-pull-out limiting.

[0069] In this embodiment, the annular connecting portion of the annular buffer seal 7 is sleeved and fixed on the outer peripheral wall of the upper connecting plate 3. Its inner peripheral surface is press-fitted with the outer peripheral wall of the upper connecting plate 3 to form a sealed connection and prevent oil leakage along the outer wall of the upper connecting plate 3. The annular mating portion extends radially outward from the outer periphery of the annular connecting portion and protrudes towards the opening of the annular limiting groove. Its outer contour matches the cross-sectional shape of the annular limiting groove, allowing it to smoothly extend into the annular limiting groove and move freely radially and vertically along the groove. The radial thickness of the annular mating portion is set to be less than the radial width of the annular limiting groove; the difference is the radial movement clearance, which provides a predetermined movement space for the horizontal displacement of the upper connecting plate 3 relative to the lifting seat 9.

[0070] The annular buffer seal 7 is integrally molded from an oil-resistant and heat-resistant elastic material, such as nitrile rubber or fluororubber, ensuring sealing performance while also possessing good elasticity and buffering energy absorption characteristics. When the sleeve flange 2 undergoes horizontal displacement relative to the riser seat 9 under horizontal seismic action, and this displacement gradually increases and reaches a preset limit, the outer circumferential surface of the annular mating part contacts and presses against the side wall of the annular limiting groove (i.e., the inner surface of the annular side wall), thereby physically preventing the upper connecting plate 3 from continuing to move horizontally, achieving the horizontal limiting function; at the same time, the compression deformation of the elastic material of the annular buffer seal 7 absorbs the collision energy, effectively buffering the impact load at the moment of contact, avoiding damage to the components from rigid collisions, and thus protecting the annular seismic rubber support 4 from damage due to excessive shear.

[0071] This embodiment sets the annular buffer seal as an integrated elastic component with an annular connecting part and an annular mating part. The annular mating part extends into the limiting groove with a radial thickness smaller than the radial width of the limiting groove to form a radially movable gap. This not only provides sufficient space for the free shear deformation of the seismic rubber bearing under small and medium earthquakes, but also achieves the dual functions of rigid limiting and flexible buffering through the elastic contact between the annular mating part and the side wall of the limiting groove when the horizontal displacement reaches the preset limit under a major earthquake. It can simultaneously complete displacement constraint and collision buffering without the need for additional independent limiting components, simplifying the structure and improving impact resistance reliability. At the same time, it is integrally molded with oil-resistant elastic material, so that the annular connecting part and the outer peripheral wall of the upper connecting plate form a reliable sealing interface with an interference fit. It can still maintain oil tightness when the shear deformation of the bearing causes relative displacement of the connection interface. The three functions of limiting, buffering and sealing are integrated into a single component, reducing the number of seals and buffers, reducing assembly complexity, and improving the overall sealing safety margin of the connection structure under strong earthquakes.

[0072] Specifically, the axial limiting gap is the vertical distance between the upper wall of the annular limiting groove and the upper surface of the annular buffer seal 7;

[0073] When the sleeve flange 2 moves upward relative to the riser seat 9 and reaches the axial limiting gap, the upper surface of the annular buffer seal 7 abuts against the upper wall of the annular limiting groove to limit the vertical separation between the sleeve flange 2 and the riser seat 9.

[0074] The integral annular limiting anti-pull-out seat 6 transmits vertical pulling force to the annular buffer seal 7 through the annular limiting part, so that the integral annular limiting anti-pull-out seat 6 simultaneously undertakes the function of anti-pull-out limiting.

[0075] In this embodiment, the specific value of the axial limiting gap is determined comprehensively based on the vertical design deformation of the annular seismic rubber bearing 4 and the initial settlement caused by the self-weight of the sleeve assembly. This ensures that the upper surface of the annular buffer seal 7 remains in a non-contact state with the upper wall of the annular limiting groove during normal operation, avoiding the vertical constraint from affecting the shear performance of the seismic rubber bearing. When a strong earthquake generates a vertical acceleration component or the sleeve is subjected to an upward impact load, the sleeve flange 2, together with the upper connecting plate 3 and the annular buffer seal 7, tends to move upward relative to the riser seat 9. When this displacement reaches the axial limiting gap, the upper surface of the annular buffer seal 7 forms a surface contact with the upper wall of the annular limiting groove (i.e., the lower surface of the annular limiting part). The integral annular limiting pull-out seat 6 transmits the vertical pull-out force to the sleeve flange 2 through the annular limiting part via the annular buffer seal 7 and the upper connecting plate 3, thereby effectively limiting the vertical separation between the sleeve assembly and the riser seat 9. Since the annular limiting part of the integral annular limiting anti-pull-out seat 6 is a continuous ring structure, it forms a continuous contact with the annular buffer seal 7 around the circumference, and the pull-out force is evenly distributed along the circumference, avoiding local stress concentration.

[0076] This embodiment reserves an axial limiting gap between the upper wall of the annular limiting groove and the upper surface of the annular buffer seal, ensuring that the connection structure does not impose additional constraints on vertical deformation under normal working conditions. This ensures that the horizontal shear energy dissipation function of the seismic rubber bearing is not interfered with by the vertical limiting gap. At the same time, when the vertical displacement reaches the limit, the surface contact between the upper surface of the annular buffer seal and the upper wall of the annular limiting groove achieves uniform pull-out force transmission throughout the circumference. The integrated structure of the integral annular limiting pull-out bearing simultaneously undertakes the dual functions of horizontal limiting and pull-out limiting, eliminating the need for separate pull-out components. This simplifies the structural hierarchy and assembly process, while ensuring the uniformity and reliability of vertical load transmission under strong earthquakes, and avoiding the risk of off-center loading and local failure that may exist in split pull-out structures.

[0077] Specifically, the annular anti-seismic rubber bearing 4 includes multiple layers of rubber and multiple layers of steel plates that are alternately arranged along the axial direction and vulcanized together.

[0078] The upper end of the annular anti-seismic rubber bearing 4 is vulcanized to the lower surface of the upper connecting plate 3, and the lower end is vulcanized to the upper surface of the lower connecting plate 5.

[0079] The annular anti-seismic rubber bearing 4 forms a force transmission path with the sleeve flange 2 and the riser seat 9 through the upper connecting plate 3 and the lower connecting plate 5, respectively.

[0080] In this embodiment, the annular seismic rubber bearing 4 comprises multiple layers of rubber and multiple layers of steel plates, which are alternately stacked along the axial direction. These layers are bonded together using a high-temperature, high-pressure vulcanization process to form an annular elastic body with predetermined shear stiffness and vertical load-bearing capacity. The rubber layers are made of high-damping rubber material, containing carbon black, plasticizers, and anti-aging agents in their formulation. This ensures a high material damping ratio while maintaining elasticity, thereby converting mechanical energy into heat energy and dissipating it during shear deformation. The steel plate layers are annular thin steel plates with inner and outer diameters consistent with the rubber layers. Each steel plate layer undergoes surface phosphating treatment and is coated with an adhesive before vulcanization to ensure the bonding strength with the rubber layers and prevent peeling failure under repeated seismic loading. The upper surface of the uppermost rubber layer of the annular seismic rubber bearing 4 is directly bonded to the lower surface of the upper connecting plate 3 through vulcanization, and the lower surface of the lowermost rubber layer is directly bonded to the upper surface of the lower connecting plate 5 through vulcanization. This forms an integral prefabricated assembly of the upper connecting plate 3, the annular seismic rubber bearing 4, and the lower connecting plate 5, achieving a reliable connection without the need for additional adhesives or fasteners. This simplifies the assembly process and ensures the continuity of the force transmission path. The central through-holes of the annular seismic rubber bearing 4, the upper connecting plate 3, and the lower connecting plate 5 are coaxially aligned during vulcanization, ensuring that conductive components inside the sleeve can pass through unobstructed.

[0081] When the riser 9 moves horizontally relative to the bushing flange 2 under horizontal seismic action, the lower connecting plate 5 moves horizontally with the riser 9, while the upper connecting plate 3 remains relatively stationary due to its fixed connection with the bushing flange 2. This results in a horizontal relative displacement between the upper and lower ends of the annular seismic rubber bearing 4, and each rubber layer undergoes shear deformation under this displacement. Since the shear modulus of rubber material is much lower than its bulk modulus, the annular seismic rubber bearing 4 achieves flexible adaptation to horizontal displacement through the shear deformation of the rubber layers, reducing the horizontal constraint stiffness on the bushing flange 2. At the same time, each rubber layer generates a hysteresis loop during cyclic shearing using its high damping characteristics, converting vibration energy into heat energy and dissipating it to the surrounding environment, thereby reducing the seismic energy transmitted to the bushing root. During shear deformation, the multi-layer steel plate mainly bears the vertical load and constrains the lateral expansion of the rubber layers, making the shear deformation of the rubber layers more uniform, while improving the overall vertical bearing capacity of the bearing, ensuring that the self-weight and operating load of the transformer bushing can still be reliably supported under horizontal seismic action.

[0082] This embodiment sets the annular seismic rubber bearing as an integral structure with alternating vulcanized connections of multiple rubber layers and multiple steel plate layers. This allows the bearing to exhibit low shear stiffness in the horizontal direction for flexible seismic isolation and high compressive stiffness in the vertical direction for stable load bearing, achieving a decoupled design of horizontal flexible seismic isolation and reliable vertical support. The rubber layer uses high-damping material and dissipates vibration energy through hysteretic deformation during cyclic shearing, reducing the bending moment and stress transmitted to the root of the sleeve from the source. At the same time, the constraint effect of the multiple steel plate layers ensures the uniformity of shear deformation of the rubber layer and the overall stability of the bearing, effectively avoiding the overturning or instability problems that may occur with pure rubber bearings under large displacement shearing, and significantly improving the seismic isolation effect and durability of the connection structure under strong earthquakes.

[0083] Specifically, the annular anti-seismic rubber bearing 4 is provided with multiple lead cores distributed circumferentially.

[0084] Each of the lead cores penetrates at least a portion of the rubber layer and the steel plate layer along the axial direction of the annular anti-seismic rubber bearing 4, and is vulcanized and connected to the rubber layer and the steel plate layer simultaneously;

[0085] The lead core is used to provide additional hysteretic energy dissipation through plastic deformation when the annular anti-seismic rubber bearing 4 undergoes shear deformation.

[0086] In this embodiment, the annular seismic rubber bearing 4 has multiple axially through holes evenly spaced along the circumference, based on an alternating axial layered structure of rubber and steel plate layers. Each through hole passes through the rubber and steel plate layers sequentially along the height direction of the bearing. During the vulcanization process, a lead core is pressed into the through hole, allowing the lead core to be simultaneously vulcanized and bonded to each rubber and steel plate layer. The lead cores are evenly spaced along the circumference, and their number is determined according to the bearing diameter and design energy consumption requirements, preferably 8 to 24, to ensure uniform energy consumption throughout the circumference. The upper end of the lead core abuts or is fixed to the lower surface of the upper connecting plate 3, and the lower end abuts or is fixed to the upper surface of the lower connecting plate 5. Thus, when the bearing undergoes shear deformation, the lead core can undergo corresponding bending or shear plastic deformation along with the shear deformation of the rubber layer. The lead core possesses low yield strength and excellent plastic deformation capacity. Under seismic loading, when the shear displacement exceeds the elastic limit of the lead core, irreversible plastic flow occurs. Through lattice slip and recrystallization, mechanical energy is converted into heat energy, significantly increasing the equivalent damping ratio and hysteretic energy dissipation capacity of the entire support, effectively suppressing the vibration response of the bushing. Simultaneously, because the lead cores are uniformly arranged circumferentially, the energy dissipation capacity of the support remains consistent throughout the entire circumference, preventing energy dissipation blind spots caused by changes in the direction of seismic loading.

[0087] This embodiment uses multiple lead cores spaced circumferentially within the annular seismic rubber bearing, which are simultaneously vulcanized and connected to each rubber layer and steel plate layer. This allows the lead cores to provide additional hysteretic energy dissipation through plastic deformation during shear deformation, significantly improving the bearing's equivalent damping ratio and energy dissipation capacity, effectively suppressing the vibration response at the casing root under seismic loading. Simultaneously, the uniform circumferential distribution of the lead cores ensures consistent energy dissipation in all directions, avoiding energy dissipation blind spots caused by the uncertainty of earthquake direction. This overcomes the shortcomings of pure rubber bearings, such as low damping ratio and insufficient energy dissipation capacity, giving the bearing both the flexible seismic isolation performance of rubber and the high-efficiency energy dissipation performance of lead cores. Furthermore, the lead cores penetrate and connect each rubber layer and steel plate layer, providing a certain degree of shear positioning under normal conditions, enhancing the coordinated deformation capacity between layers, and improving the structural integrity and fatigue durability of the bearing under repeated seismic loading.

[0088] Specifically, each of the lead cores is provided with an electromagnetic induction coil on its outer periphery. The electromagnetic induction coil is embedded in the rubber layer adjacent to the lead core and is electrically connected to an external controllable excitation power supply.

[0089] The electromagnetic induction coil is used to generate an axial magnetic field around the lead core when the controllable excitation power supply is energized. When the annular anti-seismic rubber support undergoes shear deformation, the lead core moves horizontally with the rubber layer and cuts the magnetic field lines of the axial magnetic field, thereby generating eddy currents inside the lead core and forming an electromagnetic damping force that hinders the movement of the lead core.

[0090] The controllable excitation power supply adjusts the magnitude of the excitation current output to each of the electromagnetic induction coils based on the real-time ground acceleration signal or the real-time relative displacement signal between the sleeve flange 2 and the riser 9, thereby dynamically adjusting the magnitude of the magnetic field strength and the eddy current damping force to achieve real-time continuous adjustment of the additional damping.

[0091] In this embodiment, an annular insulating frame is pre-fitted around the outer periphery of each lead core before vulcanization molding. The electromagnetic induction coil is wound in the annular groove of the annular insulating frame, so that the electromagnetic induction coil is coaxially arranged with the lead core and does not directly contact it. The annular insulating frame is embedded in the rubber layer adjacent to the lead core. The leads of each electromagnetic induction coil are led out through the lower connecting plate 5 along the inside of the annular anti-vibration rubber support 4 and connected to the controllable excitation power supply provided on the outer wall of the riser 9.

[0092] During normal operation, the controllable excitation power supply maintains zero current output, and the lead core provides reference hysteresis energy dissipation solely through its inherent plastic deformation. When the external seismic acceleration sensor detects that the seismic input exceeds the preset trigger threshold, the controllable excitation power supply dynamically calculates and outputs the corresponding excitation current to each electromagnetic induction coil based on the real-time detected seismic acceleration amplitude and frequency, or based on the real-time relative displacement amplitude between the sleeve flange 2 and the riser 9 fed back by the displacement sensing unit. After the excitation current is applied, the electromagnetic induction coil generates an axial magnetic field surrounding the lead core. When the support undergoes shear deformation, the lead core moves horizontally, cutting the magnetic field lines and generating eddy currents inside the lead core. These eddy currents generate a Lorentz force opposite to the direction of motion, forming additional electromagnetic damping. This electromagnetic damping force is positively correlated with the speed of the lead core's movement; the faster the movement, the greater the damping. Furthermore, the response time is only on the order of milliseconds, enabling real-time adjustment during earthquakes.

[0093] The stronger the seismic motion, the greater the output current of the controllable excitation power supply, the higher the magnetic field strength, and the greater the eddy current damping force generated during the lead core movement, thus increasing the equivalent damping ratio of the support. When the seismic motion weakens, the excitation current decreases or even returns to zero, and the electromagnetic damping effect weakens or disappears simultaneously, allowing the support to return to the baseline energy dissipation state of a pure lead core. This achieves real-time adaptive adjustment of the additional damping according to changes in earthquake intensity, avoiding excessive additional damping during minor earthquakes that leads to excessive stiffness of the isolation layer and decreased isolation efficiency, and also avoiding insufficient damping during major earthquakes that leads to excessive bushing response. Furthermore, this electromagnetic damping is a velocity-dependent non-contact energy dissipation mechanism, independent of and complementary to the inherent plastic hysteresis energy dissipation of the lead core. The synergistic work of the two can significantly improve the energy dissipation efficiency and adaptability of the support under seismic input across the entire frequency band.

[0094] Specifically, the lower connecting plate 5 is disposed on the top of the lifting seat 9, and the lower surface of the lower connecting plate 5 is supported on the upper surface of the top flange of the lifting seat 9.

[0095] The annular mounting part of the integral annular limiting anti-pull-out seat 6 is pressed onto the upper surface of the lower connecting plate 5, and the lower connecting plate 5 is simultaneously pressed and fixed to the top flange of the lifting seat 9 by the mounting bolts 8.

[0096] In this embodiment, the lower connecting plate 5 is a circular flat plate structure with an outer diameter larger than that of the circular anti-seismic rubber bearing 4, and an inner diameter consistent with that of the circular anti-seismic rubber bearing 4, to ensure that the central through hole is penetrating and flat. The lower surface of the lower connecting plate 5 directly adheres to the upper surface of the top flange of the riser seat 9, and the two are in planar contact. A positioning stop or positioning mark can be provided on the contact surface to facilitate quick alignment during installation. The annular mounting part of the integral annular limiting anti-pull-out seat 6 is a circular flat plate structure, and its bottom surface is directly pressed against the outer edge area of ​​the upper surface of the lower connecting plate 5 during assembly. That is, the annular mounting part clamps the lower connecting plate 5 axially between the top flange of the riser seat 9 and the annular mounting part. Multiple mounting bolts 8 are evenly distributed circumferentially. They pass sequentially through the through holes on the annular mounting part and the corresponding through holes on the lower connecting plate 5, and are then screwed into the corresponding threaded holes on the top flange of the riser seat 9. Tightening the mounting bolts 8 generates an axial clamping force, simultaneously pressing and fixing the annular mounting part, the lower connecting plate 5, and the top flange of the riser seat 9. This overlapping fixing method eliminates the need for a separate connector for the lower connecting plate 5, reducing the number of bolts and assembly steps. Simultaneously, it ensures reliable fixing between the lower end of the annular seismic rubber bearing 4 and the riser seat 9, allowing the horizontal movement of the riser seat 9 under seismic action to be effectively transmitted to the lower end of the annular seismic rubber bearing 4 through the lower connecting plate 5.

[0097] This embodiment achieves reliable fixation between the lower connecting plate and the riser by pressing the annular mounting part of the integral annular limiting anti-pullback seat onto the upper surface of the lower connecting plate, and simultaneously pressing and fixing the annular mounting part and the lower connecting plate to the top flange of the riser seat using the same set of mounting bolts. This eliminates the need for separate connecting parts for the lower connecting plate, reduces the number of bolts and assembly steps, and simplifies the connection structure and installation process. At the same time, the overlapping structure allows the installation of the lower connecting plate and the limiting anti-pullback seat to be completed simultaneously, ensuring a uniform distribution of the surface contact clamping force between the lower connecting plate and the top flange of the riser seat. This avoids local warping or uneven stress that may occur due to separate fixation, thereby ensuring that the horizontal movement of the riser seat under seismic action can be uniformly transmitted to the lower end of the annular seismic rubber bearing through the lower connecting plate. This improves the reliability of force transmission and the uniformity of bearing shear deformation, and facilitates rapid installation and subsequent disassembly and maintenance during the retrofitting of existing transformers.

[0098] Specifically, the radial movable gap is not less than the design shear displacement of the annular anti-seismic rubber bearing 4;

[0099] The radial dimension of the annular limiting groove is configured such that: before the annular anti-seismic rubber bearing 4 reaches the allowable shear displacement, the sidewall of the annular limiting groove and the annular buffer seal 7 maintain the radial movement gap, without restricting the horizontal movement of the upper connecting plate 3; when the horizontal displacement reaches the limit value of the radial movement gap, the sidewall of the annular limiting groove abuts against the annular buffer seal 7 to achieve horizontal limiting of the upper connecting plate 3.

[0100] Specifically, the sleeve flange 2 and the upper connecting plate 3 are fixedly connected by a plurality of first fasteners distributed circumferentially at intervals;

[0101] An adjusting shim is provided between the upper surface of the upper connecting plate 3 and the lower surface of the sleeve flange 2 to compensate for the installation gap.

[0102] In this embodiment, the specific value of the radial movable gap is determined based on the design shear displacement of the annular seismic rubber bearing 4. That is, the width of the radial movable gap is set to be greater than or equal to the maximum horizontal shear displacement of the bearing under the design earthquake action. This ensures that within the design earthquake range, the outer circumferential surface of the annular mating part of the annular buffer seal 7 remains in non-contact with the sidewall of the annular limiting groove (i.e., the inner surface of the annular sidewall). The upper connecting plate 3 and the sleeve flange 2 can freely shear and deform with the bearing without being constrained by horizontal limiting, thereby ensuring that the bearing fully performs its functions of flexible seismic isolation and energy dissipation. When the actual earthquake action exceeds the design intensity, and the shear displacement of the annular seismic rubber bearing 4 increases and reaches its allowable shear displacement, the outer circumferential surface of the annular mating part of the annular buffer seal 7 just contacts or begins to press against the sidewall of the annular limiting groove. This physically restricts the upper connecting plate 3 and the sleeve flange 2 from continuing to move horizontally, preventing the annular seismic rubber bearing 4 from tearing, peeling, or permanently damaging due to excessive shear. The radial dimension of the annular limiting groove, i.e. the radial depth from the bottom of the groove to the opening of the groove, together with the difference in radial thickness of the annular buffer seal 7, determines the aforementioned radial movement clearance. By reasonably matching the aforementioned dimensional parameters, the triggering time of the horizontal limit can be precisely matched with the allowable shear displacement of the support.

[0103] The bushing flange 2 and the upper connecting plate 3 are detachably fixedly connected by multiple first fasteners, such as high-strength bolts or double-ended studs, spaced apart circumferentially. These first fasteners are evenly distributed circumferentially to ensure a balanced distribution of clamping force throughout the circumference. An adjusting shim is positioned between the upper surface of the upper connecting plate 3 and the lower surface of the bushing flange 2. Its thickness is selected based on the actual gap between the two surfaces during installation. This shim compensates for loose fits caused by machining errors or installation deviations, ensuring the flatness and uniformity of the connection surface. The adjusting shim can be a metal shim or a spiral wound metal shim, which can both adjust the installation gap and assist in achieving a sealing function, preventing transformer oil leakage along the flange connection interface.

[0104] This embodiment sets the radial movable gap to be no less than the design shear displacement of the annular seismic rubber bearing, allowing the bearing to freely shear deform within the design earthquake range. This fully utilizes its flexible isolation and hysteretic energy dissipation functions without interference from the limiting components, avoiding premature limiting that could lead to a decrease in the bearing's isolation effect or a sudden increase in stiffness. Simultaneously, by rationally matching the radial dimensions of the annular limiting groove, the horizontal limiting is precisely triggered when the bearing reaches its allowable shear displacement. This protects the bearing from excessive shear failure and avoids impact damage to structural components from rigid collisions, significantly improving the adaptability and safety of the connection structure under different levels of seismic loading. Furthermore, the cooperation of the first fastener and the adjusting shim ensures reliable fixing and installation accuracy between the sleeve flange and the upper connecting plate, while also facilitating adjustments to the installation gap according to actual working conditions. This reduces the requirements for processing and assembly precision, improving the convenience and versatility of engineering implementation.

[0105] Specifically, the central through hole of the annular anti-seismic rubber bearing 4, the central through hole of the upper connecting plate 3, and the central through hole of the lower connecting plate 5 are coaxially arranged;

[0106] The inner diameter of the central through hole is larger than the maximum outer diameter of the conductive component inside the sleeve 1, so as to provide clearance space for the conductive component when the annular anti-seismic rubber support 4 undergoes shear deformation.

[0107] In this embodiment, the central through-holes of the annular seismic-resistant rubber bearing 4, the upper connecting plate 3, and the lower connecting plate 5 are arranged along the same vertical axis in the assembled state, ensuring that the three are coaxially connected and forming a through channel through which the conductive components (such as conductive rods or current-carrying conductors) inside the sleeve 1 pass from bottom to top. The inner diameter of the central through-hole is set to be larger than the maximum outer diameter of the conductive component and its associated insulating layer, and a predetermined gap is left between them in the radial direction. This gap is at least not less than the design shear displacement of the annular seismic-resistant rubber bearing 4, so as to ensure that even if the annular seismic-resistant rubber bearing 4 undergoes maximum design shear deformation within the seismic fortification range, the outer peripheral surface of the conductive component and the inner wall of each central through-hole remain in a non-contact state, avoiding rigid collision, friction, or extrusion damage between the conductive component and the inner wall of the through-hole. Meanwhile, the inner wall surfaces of the central through holes of the upper connecting plate 3, the annular anti-seismic rubber support 4, and the lower connecting plate 5 are all coated with an insulating coating or provided with an insulating bushing to enhance the electrical insulation reliability between the conductive components and the grounded metal components and prevent flashover or breakdown accidents under high voltage operating conditions.

[0108] When the annular anti-seismic rubber bearing 4 undergoes shear deformation, a horizontal relative displacement occurs between the upper connecting plate 3 and the lower connecting plate 5. However, since the inner diameter of each central through hole is larger than the maximum outer diameter of the conductive component, and the reserved gap is sufficient to accommodate the shear displacement of the bearing, the conductive component can swing freely within the central through hole or remain in place. It will not be subject to additional constraints or bending stress due to the shear deformation of the bearing. This ensures both the continuity of the electrical connection of the conductive component and avoids the conductive component bearing additional mechanical loads during the shear deformation of the anti-seismic rubber bearing, ensuring that the electrical connection interface and the mechanical isolation interface are independent of each other and do not interfere with each other.

[0109] This embodiment coaxially sets the central through-holes of the annular seismic rubber bearing, the upper connecting plate, and the lower connecting plate, with the inner diameter of each central through-hole larger than the maximum outer diameter of the conductive component inside the sleeve. A radial clearance not less than the design shear displacement of the bearing is reserved between the conductive component and the inner wall of the through-hole. This allows the conductive component to pass freely without contacting or interfering with the inner wall of the through-hole when the bearing undergoes horizontal shear deformation. This avoids additional bending stress on the conductive component due to bearing deformation and prevents collision damage and insulation failure between the conductive component and the metal components, ensuring the safety and reliability of the electrical connection. At the same time, there is no mechanical coupling between the conductive component and the seismic isolation structure, realizing a complete decoupling design between the electrical path and the seismic isolation path. This allows them to work independently under seismic action without affecting each other, fundamentally solving the electrical insulation risk and additional stress problem caused by the deformation of the conductive component along with the connecting structure in traditional rigid connections.

[0110] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A seismic-resistant connection structure for a large transformer bushing, characterized in that, include: Sleeve flange, upper connecting plate, annular anti-seismic rubber bearing, lower connecting plate, integral annular limiting anti-pull-out seat and annular buffer seal; The sleeve flange is fixedly connected to the upper connecting plate, and the annular anti-seismic rubber support is disposed between the upper connecting plate and the lower connecting plate. The annular anti-seismic rubber support, the upper connecting plate and the lower connecting plate all have a central through hole for the conductive components inside the sleeve to pass through. The integral annular limiting anti-pull-out seat is arranged around the outer periphery of the annular anti-seismic rubber bearing and is fixed to the lifting seat by a plurality of mounting bolts arranged at intervals along the circumference. The inner circumferential surface of the integral annular limiting anti-pull-out seat is provided with an annular limiting groove facing the opening of the upper connecting plate, and the annular buffer seal is provided on the outer circumference of the upper connecting plate and extends into the annular limiting groove. A radial movable gap is provided between the annular buffer seal and the annular limiting groove to allow the upper connecting plate to move horizontally relative to the lifting seat, and an axial limiting gap is provided. The axial limiting gap is used to allow the upper connecting plate to generate axial displacement relative to the lifting seat. When the axial displacement reaches the limit value of the axial limiting gap, the integral annular limiting anti-pull-out seat abuts against the annular buffer seal to withstand the vertical load and provide anti-pull-out limiting. The annular anti-seismic rubber bearing is used to generate elastic deformation and dissipate vibration energy when the riser and the sleeve flange move relative to each other. The elastic deformation includes at least horizontal shear deformation.

2. The structure according to claim 1, characterized in that, The integral annular limiting anti-pull-out seat includes an annular mounting part, an annular sidewall extending upward from the annular mounting part, and an annular limiting part extending inward from the upper end of the annular sidewall. The annular limiting part and the annular sidewall together define the annular limiting groove, and the opening of the annular limiting groove is open towards the upper connecting plate; The annular mounting portion is supported on the top flange of the riser, and a plurality of mounting bolts are evenly distributed around the circumference of the annular mounting portion, thereby detachably connecting the annular mounting portion to the top flange of the riser.

3. The structure according to claim 1, characterized in that, The annular buffer seal includes an annular connecting part that connects to the outer periphery of the upper connecting plate and an annular mating part that extends into the annular limiting groove. The shape of the annular mating part is adapted to the groove shape of the annular limiting groove, and the radial thickness of the annular mating part is less than the radial width of the annular limiting groove to form the radial movable gap. The annular buffer seal is made of oil-resistant elastic material. When the horizontal displacement of the sleeve flange relative to the riser reaches a preset limit, the annular buffer seal contacts the side wall of the annular limiting groove to limit the maximum horizontal displacement of the sleeve flange and buffer the contact impact.

4. The structure according to claim 1, characterized in that, The axial limiting gap is the vertical distance between the upper wall of the annular limiting groove and the upper surface of the annular buffer seal. When the axial displacement of the sleeve flange relative to the riser seat reaches the limit value of the axial limiting gap, the upper surface of the annular buffer seal abuts against the upper wall of the annular limiting groove to restrict the vertical separation between the sleeve flange and the riser seat. The integral annular limiting anti-pull-out seat abuts against the annular buffer seal through the annular limiting part to transmit vertical pull-out force, so that the integral annular limiting anti-pull-out seat can simultaneously perform the function of anti-pull-out limiting.

5. The structure according to claim 1, characterized in that, The annular seismic rubber bearing includes multiple layers of rubber and multiple layers of steel plates that are alternately arranged along the axial direction and vulcanized together. The upper end of the annular anti-seismic rubber bearing is vulcanized to the lower surface of the upper connecting plate, and the lower end is vulcanized to the upper surface of the lower connecting plate. The annular seismic rubber bearing forms a force transmission path with the sleeve flange and the riser seat through the upper connecting plate and the lower connecting plate, respectively.

6. The structure according to claim 5, characterized in that, The annular anti-seismic rubber bearing contains multiple lead cores spaced apart along the circumference. Each of the lead cores penetrates at least a portion of the rubber layer and the steel plate layer along the axial direction of the annular anti-seismic rubber bearing, and is vulcanized and connected to the rubber layer and the steel plate layer simultaneously; The lead core is used to provide additional hysteretic energy dissipation through plastic deformation when the annular anti-seismic rubber bearing undergoes shear deformation.

7. The structure according to claim 1, characterized in that, The lower connecting plate is disposed on the top of the lifting seat, and the lower surface of the lower connecting plate is supported on the upper surface of the top flange of the lifting seat; The annular mounting part of the integral annular limiting anti-pull-out seat is pressed onto the upper surface of the lower connecting plate, and the lower connecting plate is simultaneously pressed and fixed to the top flange of the lifting seat by the mounting bolts.

8. The structure according to claim 1, characterized in that, The radial movable gap is not less than the design shear displacement of the annular seismic rubber bearing; The radial dimension of the annular limiting groove is configured such that, before the annular anti-seismic rubber bearing reaches the allowable shear displacement, the sidewall of the annular limiting groove and the annular buffer seal maintain the radial movement gap, without restricting the horizontal movement of the upper connecting plate; when the horizontal displacement reaches the limit value of the radial movement gap, the sidewall of the annular limiting groove abuts against the annular buffer seal to achieve horizontal limiting of the upper connecting plate.

9. The structure according to claim 1, characterized in that, The sleeve flange and the upper connecting plate are fixedly connected by a plurality of first fasteners distributed circumferentially. An adjusting shim is provided between the upper surface of the upper connecting plate and the lower surface of the sleeve flange to compensate for the installation gap.

10. The structure according to claim 1, characterized in that, The central through hole of the annular anti-seismic rubber bearing, the central through hole of the upper connecting plate, and the central through hole of the lower connecting plate are coaxially arranged. The inner diameter of the central through hole is larger than the maximum outer diameter of the conductive component inside the sleeve, so as to provide clearance space for the conductive component when the annular anti-seismic rubber bearing undergoes shear deformation.

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