A cable branch box busbar mounting structure and a branch box

Abstract

The application relates to the technical field of branch boxes, in particular to a cable branch box busbar mounting structure and a branch box. The branch box comprises a box body, a plurality of busbar rows are arranged in the box body, and a busbar clamp is clamped and connected on the busbar row. The busbar clamp comprises a first clamp jaw and a second clamp jaw, and the first clamp jaw and the second clamp jaw are rotationally connected through a torsion spring. Isolating components are fixedly arranged on the clamping sides of the first clamp jaw and the second clamp jaw, the two isolating components are oppositely arranged, a touch pressure component is movably arranged in each isolating component, and the touch pressure component can reciprocatingly displace in the isolating component along the clamping direction of the busbar row. In the state that the busbar clamp is clamped on the busbar row, the working surfaces of the two touch pressure components are respectively tightly attached to the two side wall surfaces of the busbar row, the isolating components bear the mechanical clamping load transmitted by the clamp jaws, the touch pressure components can be self-adaptively expanded and contracted along with the thickness deformation of the busbar row caused by thermal expansion and cold contraction, and the touch pressure components always maintain the tight conductive contact with the surface of the busbar row.

Description

Technical Field

[0001] This invention relates to the field of branch box technology, and more specifically, to a cable branch box busbar installation structure and branch box. Background Technology

[0002] Cable distribution boxes are core power distribution equipment in power distribution networks that realize cable branching and transfer. They are widely used in urban municipal power supply, residential community power distribution, industrial park power distribution, and other scenarios. As the main current-carrying component inside the cable distribution box, the busbar undertakes the core functions of power collection and multi-path distribution. The stability and contact reliability of its installation and fixing structure directly determine the overall operational safety and service life of the distribution box.

[0003] In the existing cable branch box assembly scheme, in order to avoid drilling and weakening the cross-sectional strength of the busbar, and at the same time improve the construction efficiency of on-site installation and capacity expansion, some vertically arranged hanging busbars adopt an integrated structure without holes. For the branch wiring operation of this type of holeless busbar, the industry generally uses hanging busbar clips as T-connection components, which can realize the rapid lead-out of branch circuits without drilling and tapping on the busbar.

[0004] Existing hanging-type busbar clamps generally adopt a clamp-shaped jaw combined with a torsion spring structure. The two conductive jaws are hinged in the middle by a pin to form a clamp body. A torsion spring is sleeved on the pin. The two torsion arms of the torsion spring abut against the tails of the upper and lower jaws respectively, providing the jaws with an inward torsional torque. During installation, pressing the tail of the jaws overcomes the spring force of the torsion spring to open the jaw head. After aligning the clamp with the busbar and inserting it, it is released. The spring rebounds and causes the jaws to grip the side wall of the busbar. Electrical conduction is achieved by the crimping contact surface between the jaw head and the busbar. Finally, the branch cable is connected through the terminal extending from the jaw to complete the busbar branching.

[0005] However, in actual operation, this type of structure is directly positively correlated with the opening and closing angle of the gripper. When the busbar is energized and heats up, it causes thermal expansion in the thickness direction. The gripper is pushed outward, which can easily lead to an increase in the torsion angle of the torsion spring, increase the clamping stress, and accelerate metal creep and elastic decay. When the busbar cools and contracts, the torsion spring angle drops back, which can cause insufficient clamping force and gaps in the contact surface, forming a vicious cycle of expansion overload fatigue and contraction gap connection.

[0006] Therefore, there is an urgent need for a cable branch box busbar installation structure and branch box to solve the above problems. Summary of the Invention

[0007] This invention provides a busbar installation structure and a branch box for a cable branch box. It achieves a functionally separated clamping structure by respectively assembling an isolation component and a pressing component on the first and second jaws of the busbar clamp. The isolation component bears the mechanical clamping load transmitted by the jaws and provides circumferential limiting for the extension and retraction displacement of the pressing component. The pressing component can reciprocate within the isolation component along the thickness direction of the busbar, and the working surface of the pressing component is always elastically fitted to the surface of the busbar using the elastic force of a disc spring. This solves the problems mentioned in the background art, namely: The existing bus clamp uses a structure in which the torsion spring directly drives the clamping claws to grip the busbar. Because the output torque of the torsion spring is positively correlated with the opening and closing angle of the clamping claws, the clamping force is overloaded when the busbar expands due to heat, which accelerates the elastic decay. When the busbar contracts due to cold, the clamping force is insufficient, resulting in contact gaps. This ultimately forms a vicious cycle of expansion overload fatigue and contraction gaps.

[0008] To achieve the above objectives, the cable branch box busbar installation structure includes a box body, inside which are provided multiple busbars, busbar clamps are clamped and connected, and the ends of the busbar clamps are connected to connectors for electrical connection with external lines. The bus clamp includes a first clamp and a second clamp, which are rotatably connected by a torsion spring. Each of the first and second clamps is provided with a handle at its tail end away from the clamping end. The handle is used to drive the two clamps to open against the torsion spring torque, thereby realizing the installation and removal of the bus clamp on the busbar. Isolation components are fixedly provided on the clamping sides of the first and second grippers. The two isolation components are arranged opposite to each other. A pressing component is movably arranged inside each isolation component. The pressing component can reciprocate and extend within the isolation component along the clamping direction of the busbar. When the busbar clamp is held in the busbar, the working surfaces of the two pressure components on both sides are pressed against the two side walls of the busbar. The isolation component bears the mechanical clamping load transmitted by the gripper. The pressure component can adaptively expand and contract with the thickness deformation of the busbar due to thermal expansion and contraction, and always maintains a tight conductive contact with the surface of the busbar.

[0009] In the above technical solution, because the clamping surfaces of the grippers are respectively equipped with mutually cooperating isolation components and contact components, the two functions of mechanical clamping and conductive contact that the grippers originally performed simultaneously are separated. In this way, the main clamping force generated by the torsion spring driving the grippers to close is entirely rigidly borne by the isolation components and directly acts on the surface of the busbar, responsible for the overall mounting and positioning of the busbar clamp and resisting cable pulling and vibration loads. The conductive contact pressure between the contact components and the busbar is entirely provided by the internal disc spring and is no longer directly bound to the output torque of the torsion spring. Therefore, when the busbar expands due to heat and causes the grippers to open slightly, the increased torsional stress of the torsion spring will only act on the bearing end surface of the isolation components and will not be significantly transmitted to the conductive contact surface, thus avoiding the problem of the torsion spring accelerating elastic creep and irreversible attenuation of clamping force due to continuous overload. Furthermore, when the busbar cools and shrinks, the disc spring can rebound on its own, pushing the contact component to extend outward along the inside of the isolation component. It always fits tightly against the surface of the busbar to fill the shrinkage gap, preventing the contact surface from becoming loose or the contact resistance from increasing due to the drop in torsion spring torque. This breaks the vicious cycle of expansion overload fatigue and loose shrinkage gap, reducing the risk of joint overheating and burning.

[0010] Based on this, the isolation assembly includes two support rods, which are respectively fixedly connected to the clamping sides of the first and second clamping jaws. The two support rods are fixedly connected to each other by a support plate. A sleeve is fixedly provided on the side of the support plate facing the busbar. The sleeves of the two isolation assemblies are arranged opposite to each other, and a pressure contact component is slidably connected inside each sleeve.

[0011] The casing is in the shape of a U-shaped frame, with a groove in the center for accommodating the touch component. The U-shaped frame provides circumferential limiting for the extension and retraction of the touch component.

[0012] In addition, the housing is made of insulating and flame-retardant material to bear the mechanical clamping load transmitted by the gripper and to achieve electrical isolation between the gripper and the contact component, so that the mechanical load-bearing force and the conductive contact force are separated from each other.

[0013] Preferably, the outer wall of the casing is arranged in a trapezoidal structure, and each of the two opposite sides of the casing is provided with a guide slope near both ends. The guide slope is used to guide the casing to smoothly enter the clamping position when the busbar clamp is inserted into the busbar.

[0014] In another technical solution, the pressure-sensitive component includes a voltage element that is slidably fitted inside the housing. The voltage element is elastically connected to the support plate by a plurality of disc springs, which are housed inside the housing and whose elastic force direction is perpendicular to the surface of the busbar.

[0015] Preferably, the voltage element is made of a copper alloy material with high conductivity, and its surface facing the busbar is the working surface, which is used to form a conductive contact with the surface of the busbar in the clamped state.

[0016] In this technical solution, the outer wall of the voltage component is provided with a slider, and the inner wall of the housing is provided with a corresponding groove. The slider is slidably connected inside the groove to constrain the voltage component to slide back and forth only in a direction perpendicular to the surface of the busbar.

[0017] Furthermore, when the disc spring is in a free state, it pushes the working surface of the voltage component beyond the end face of the housing; when the busbar clamp is held on the busbar, the voltage component is pushed into the housing by the busbar in the opposite direction until the working surface of the voltage component is flush with the end face of the housing. At this time, the compression of the disc spring is half of its rated total stroke, providing bidirectional extension and retraction compensation margin.

[0018] The second objective of this invention is to provide a busbar mounting structure for operating a cable branch box including any one of the above-described methods, comprising the following steps: Step 1: Hold the handles at the tails of the first and second grippers to overcome the torsion spring torque and make the two grippers rotate relative to each other, thereby causing the isolation components and contact components at the gripping ends of the two grippers to separate and open. Step 2: Align the two open jaws with the predetermined clamping position of the busbar, release the handle, and the torsion spring will rebound and drive the two jaws to rotate in opposite directions, so that the end faces of the housings of the two isolation components abut against the two side surfaces of the busbar, forming a mechanical limit. Step 3: During the process of the housing abutting against the busbar, the voltage component is pushed into the housing by the surface of the busbar, compressing the disc spring until the working surface of the voltage component is flush with the end face of the housing. The disc spring is compressed to half of the rated stroke, so that the voltage component is pressed against the surface of the busbar with constant elastic pressure, thus completing the clamping and installation of the busbar clamp. Step 4: When the busbar expands in the thickness direction due to heat generated by power, the two sides of the busbar push the voltage component outward. The voltage component compresses the disc spring along the inner wall of the housing. The compression of the disc spring varies between half of the rated stroke and the maximum value. Its output elastic force increase is suppressed within the preset range. The voltage component always keeps in close contact with the surface of the busbar. When the busbar contracts in the thickness direction due to cooling caused by power failure, the disc spring releases elastically and pushes the voltage component to slide towards the busbar. The compression varies between half of the rated stroke and zero. The working surface of the voltage component continuously presses against the surface of the busbar to maintain an effective conductive contact area. Therefore, the voltage components adapt to the thickness deformation caused by the thermal expansion and contraction of the busbar, and the elastic force of the disc spring always fluctuates bidirectionally around half of the rated stroke, so that the contact pressure remains basically constant.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By fixing isolation components on the clamping sides of the first and second jaws of the busbar clamp, and movably setting a pressure-contact component that can reciprocate and extend along the thickness direction of the busbar inside the isolation components, the two functions of mechanical clamping and conductive contact originally performed by the jaws can be separated. The isolation components rigidly bear the torsion spring clamping load transmitted by the jaws to be responsible for the overall mounting positioning and tensile fixation of the busbar clamp, while the pressure-contact component independently provides the conductive contact pressure with the busbar. After the two are decoupled, the slight opening and closing of the jaws caused by the thermal expansion and contraction of the busbar no longer directly affects the pressure value of the conductive contact surface, thereby eliminating the inherent defects of thermal expansion clamping force overload and cold contraction clamping force caused by the positive correlation between the output torque of the torsion spring and the opening and closing angle of the jaw in the existing structure.

[0020] 2. By setting the contact pressure assembly to include a voltage component that slides inside the housing and a disc spring connected between the voltage component and the support plate, and compressing the disc spring to half of its rated total stroke when the busbar clamp is held on the busbar, the disc spring is in the flat section of the force-displacement curve in the working state. When the busbar expands in the thickness direction due to heat generated by power, the voltage component compresses the disc spring along the inner wall of the housing. The amount of compression varies between half of the rated stroke and the maximum value, but the increase in output elastic force is suppressed within the preset range. When the busbar contracts in the thickness direction due to cooling caused by power failure, the disc spring releases elastically and pushes the voltage component to slide towards the busbar. Its compression varies between half of the rated stroke and zero, but the decrease in output elastic force is also suppressed. The working surface of the voltage component always adheres to the surface of the busbar with an approximately constant elastic pressure, so that the elastic force of the disc spring fluctuates bidirectionally around half of the rated stroke, ensuring that the contact component can respond in time and maintain effective conductive contact no matter which direction the busbar changes thickness. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the busbar clamping structure of the present invention; Figure 3 This is a schematic diagram of the busbar clamp structure of the present invention; Figure 4 This is a side view of the busbar clamping structure of the present invention; Figure 5 This is a side view of the internal structure of the isolation component of the present invention; Figure 6 This is a schematic diagram of the isolation component structure of the present invention; Figure 7 This is a schematic diagram of the pressure-sensitive component structure of the present invention; Figure 8This is a schematic diagram of the internal structure of the casing of the present invention.

[0022] The meanings of the labels in the diagram are as follows: 1. Enclosure; 11. Busbars; 2. Busbar clamp; 21. First clamping jaw; 22. Second clamping jaw; 23. Handle; 24. Isolation assembly; 240. Support rod; 241. Support plate; 242. Housing; 25. Press-sensitive assembly; 250. Voltage-sensitive component; 251. Disc spring; 26. Slider; 260. Slide. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 Currently, existing hanging-type busbar clamps (2) suffer from the problem of linkage between the torsion spring torque and the clamp opening angle. Thermal expansion and contraction of the busbar can easily lead to torsion spring creep, poor contact, and overheating faults. Furthermore, there is no way to compensate for clamping pressure on-site. This invention provides a cable branch box, see [link to relevant documentation]. Figures 1-2 As shown, it includes a housing 1, inside which multiple busbars 11 are installed, and busbar clamps 2 are clamped and connected to the busbars 11. The ends of the busbar clamps 2 are provided with connectors for electrical connection to external lines. In the power distribution circuit architecture of the cable branch box, the busbar 11 is the main conductive carrier inside the box. After the external incoming cable is connected to the incoming end of the busbar 11, the power is conducted longitudinally along the busbar 11. The busbar clamp 2, as a T-connection shunt component, is assembled on the flat side wall of the busbar 11 in a clamping manner. Its internal conductive structure forms contact with the surface of the busbar 11 to build a conductive path. After the external branch line is connected to the connector, the power on the main busbar can be distributed to each branch circuit to realize multi-path power distribution output.

[0025] Since the existing hanging busbar clamp 2 generally adopts a clamp-type hinge structure, the two conductive jaws are hinged in the middle by a pin to form a clamp body. A torsion spring is installed on the pin to provide the closing torque. During installation, the operator presses the handle 23 at the tail of the jaw, using the pin as a fulcrum to overcome the torsional elasticity of the torsion spring, so that the clamping end of the jaw head opens. After aligning the opened jaw with the side wall of the busbar and locking it in, the operator releases the handle 23. The torsion spring releases the pre-tightening torque, causing the two jaws to close towards each other. The conductive clamping surface of the jaw head directly hugs the side wall of the busbar. The clamping pressure is maintained by the continuous torque of the torsion spring, and mechanical fixing and electrical conduction are completed at the same time. In this structure, the grippers serve both the mechanical clamping load transfer function and the current carrying function of conductive contact. The output torque of the torsion spring directly determines the clamping force of the conductive contact surface. Since the torsional torque of the torsion spring is positively correlated with the opening and closing angle, when the busbar is energized and generates thermal expansion in the thickness direction, the grippers are pushed outward, the torsion angle of the torsion spring increases, and the clamping stress rises sharply. Under long-term repeated action, the torsion spring is prone to metal creep, and its elastic properties irreversibly decay. When the busbar is de-energized and cooled, its thickness shrinks, the opening and closing angle of the grippers decreases, and the output torque of the torsion spring drops synchronously. The clamping force of the conductive contact surface decreases accordingly, and in severe cases, gaps may appear on the contact surface, causing increased contact resistance, local overheating, or even ablation failure. Furthermore, the clamping pressure in this structure is deeply bound to the state of the torsion spring. After the torsion spring loosens, pressure compensation cannot be performed on-site, and the entire clamp must be replaced, resulting in high maintenance costs and significant impact from power outages.

[0026] To solve the above problems, see [link to relevant documentation]. Figure 3 As shown, the busbar clamp 2 in this embodiment includes a first clamping jaw 21 and a second clamping jaw 22. The first clamping jaw 21 and the second clamping jaw 22 are hinged together at the middle. A torsion spring is installed at the hinge. The torsion spring is used to apply a clamping torque to the first clamping jaw 21 and the second clamping jaw 22 to pull them together. A handle 23 is provided at the tail end of the first clamping jaw 21 and the second clamping jaw 22 away from the clamping end. The operator can drive the two clamping jaws to open against the torsion spring torque by holding the handle 23 and applying force, so as to realize the installation and removal of the busbar clamp 2 on the busbar 11. Isolation components 24 are fixedly provided on the clamping sides of the first gripper 21 and the second gripper 22 respectively. The two sets of isolation components 24 are arranged symmetrically facing each other. Each set of isolation components 24 has a pressing component 25 movably embedded inside. The pressing component 25 can reciprocate and extend within the isolation component 24 along the clamping direction of the busbar 11.

[0027] See Figure 6 and Figure 7 As shown, the isolation assembly 24 is composed of support rods 240, support plates 241 and housing 242 forming a load-bearing frame. The two support rods 240 are symmetrically fixed on the left and right sides of the gripper clamping surface and extend outward along the clamping direction. The support plates 241 are laterally connected to the outer ends of the two support rods 240 to form a stable frame-type load-bearing structure. This structure can distribute the concentrated torsion spring torque transmitted at the clamp hinge into two force points through two support rods 240, and then evenly transmit it to the front sleeve 242 through the support plate 241. This avoids stress concentration caused by single-point force, ensures uniform force on the clamping end face, improves the overall load-bearing capacity and structural stability, resists the lateral pull of the branch cable and the vibration of the box 1 during operation, and prevents the busbar clamp 2 from tilting or loosening.

[0028] in, Figure 4 In the middle, the casing 242 is fixedly installed on the side of the support plate 241 facing the busbar 11, and the two casings 242 are arranged symmetrically facing each other. Figure 6 In the middle, the housing 242 adopts a U-shaped frame structure, with the center recessed inward to form a groove, and the touch component 25 is embedded in the inside of the groove. The U-shaped frame structure can form a circumferential enclosure and limit the movement of the touch component 25 from all sides, strictly constraining the movement direction of the touch component 25 to the axial direction of the groove, that is, the direction perpendicular to the surface of the busbar 11. This avoids problems such as lateral displacement and torsional tilting of the touch component 25 during the process of being pressed and extended, and ensures that the working surface of the touch component 25 always remains parallel and in contact with the side wall of the busbar 11, eliminating problems such as poor local contact and uneven force caused by the misalignment of the contact surface.

[0029] In the above technical solution, the housing 242 is integrally made of insulating and flame-retardant material. This material serves as the main mechanical bearing surface. The housing 242 directly abuts against the surface of the busbar 11, bearing all the torsion spring clamping force transmitted by the grippers. It undertakes all mechanical functions such as mounting and positioning of the busbar clamp 2, tensile resistance, and vibration resistance, replacing the force-bearing mode in the original structure where the conductive surface of the grippers bears the force simultaneously. Furthermore, the insulating housing 242 can form a reliable electrical isolation barrier between the metal body of the grippers and the internal contact component 25, blocking the conductive path between the grippers and the contact component 25. This allows the mechanical bearing function and the conductive contact function to be undertaken by two independent components, completely decoupling the functions of force and electricity. Therefore, the fluctuation of the torsion spring torque only acts on the mechanical bearing surface of the insulating housing 242 and will not be transmitted to the internal conductive contact parts, thereby cutting off the influence of the torsion spring torque change on the conductive contact pressure.

[0030] See Figure 4 and Figure 5As shown, the outer wall of the housing 242 is generally trapezoidal, and the two opposite end faces of the two housings 242 are provided with smooth transition guide slopes. When installing the busbar clamp 2 on site, the operator does not need to align the end face of the housing 242 with the side wall of the busbar with perfect precision. When there is a slight offset between the end face of the housing 242 and the edge of the busbar, the guide slope can first contact the side of the busbar. As the clamps close, the busbar slides into the central area of ​​the housing 242 along the guide slope, automatically completing the alignment calibration. This reduces the alignment accuracy requirements for on-site installation, and is especially suitable for the working environment where the internal space of the cable branch box is small and the visibility is poor, improving installation efficiency. At the same time, it avoids the edge of the housing 242 scratching the protective coating on the surface of the busbar during the installation process, ensuring the anti-corrosion performance and conductivity of the busbar.

[0031] See Figure 7 and Figure 8 As shown, the pressure-sensitive component 25 is movably embedded in the groove of the housing 242, mainly composed of a voltage element 250 and a disc spring 251, and can reciprocate and extend within the housing 242 along the thickness direction of the busbar 11; wherein, the voltage element 250 is the conductive body of the pressure-sensitive component 25, made of a copper alloy material with high conductivity, and has excellent conductivity, wear resistance, and creep resistance; furthermore, the side of the voltage element 250 facing the busbar 11 is a flat working surface, which is tightly fitted to the side wall of the busbar 11 in the clamping state, forming a conductive path from the busbar 11 to the branch circuit; A reliable electrical connection is achieved between the voltage component 250 and the conductive substrate of the gripper through a flexible braided copper wire. The two ends of the flexible braided copper wire are fixedly connected to the back of the voltage component 250 and the conductive part of the gripper, respectively, forming a conductive path. This connection method is a conventional and necessary feature of the floating conductive structure. Since the voltage component 250 can reciprocate within the housing 242 and there is relative movement between it and the gripper body, a rigid conductor cannot be used for direct connection. Therefore, a flexible braided copper wire with flexible deformation capability must be used to construct a complete current conduction path to ensure that the electrical energy on the busbar 11 is conducted to the gripper body through the voltage component 250 and the flexible braided copper wire, and finally output to the branch circuit through the end connector, ensuring the continuity and reliability of current carrying. At the same time, the flexible braided copper wire can bend and deform synchronously with the expansion and contraction of the voltage component 250, without forming a rigid constraint on the floating movement of the voltage component 250. This ensures the normal realization of the thermal expansion and contraction adaptive compensation function, and also avoids fatigue fracture of the connection part caused by repeated expansion and contraction, thus improving the long-term operational stability of the conductive path.

[0032] Figure 8In this design, a raised slider 26 is provided on the outer wall of the voltage component 250, and a corresponding groove 260 extending along the clamping direction is provided on the inner wall of the groove of the housing 242. The slider 26 is fitted into the groove 260 and can slide smoothly along the groove 260. Through the cooperation structure of the slider 26 and the groove 260, the extension and retraction movement of the voltage component 250 is guided and limited, constraining the movement direction of the voltage component 250 and ensuring that it always moves back and forth in a direction perpendicular to the surface of the busbar 11. This prevents the voltage component 250 from deflecting or getting stuck in the groove and ensures the smoothness of the thermal expansion and contraction adaptive process. At the same time, the two ends of the groove 260 can mechanically limit the sliding stroke of the slider 26, limiting the maximum extension and maximum retraction of the voltage component 250, preventing the voltage component 250 from falling out of the housing 242, and also preventing the disc spring 251 from being over-compressed and causing plastic failure, thus protecting the elastic component.

[0033] It should be noted that the disc spring 251 is located between the back of the voltage component 250 and the inner side of the support plate 241, and is fully accommodated in the groove of the housing 242. The spring force direction is consistent with the clamping direction and perpendicular to the surface of the busbar 11, and is used to independently provide the voltage component 250 with an elastic clamping force toward the busbar 11. In this embodiment, when the disc spring 251 is in a free, unassembled state, it can push the working surface of the voltage component 250 beyond the end face of the housing 242 by a certain distance. When the busbar clamp 2 is clamped and installed in place and the end face of the housing 242 is completely against the side wall of the busbar 11, the voltage component 250 is pushed into the housing 242 by the busbar 11 in the opposite direction until the working surface of the voltage component 250 is basically flush with the end face of the housing 242. At this time, the compression of the disc spring 251 is exactly half of its rated total stroke. The initial working point of the disc spring 251 is set at half of the rated total stroke. The core purpose is to reserve a bidirectional extension compensation margin, and at the same time, to achieve an approximately constant pressure contact effect by utilizing the flat section of the force-displacement curve of the disc spring 251. Specifically, with the semi-compressed state as the initial equilibrium point, the voltage component 250 can be further compressed into the housing 242, or it can spring back and extend outward from the housing 242, with sufficient stroke space in both directions. When the busbar expands due to heat, increasing its thickness, it pushes the voltage component 250 back into the housing 242. The compression of the disc spring 251 changes from half its stroke to its maximum stroke. Within this range, the increase in the output force of the disc spring 251 is minimal, and the conductive contact pressure remains relatively stable, preventing a sudden increase in contact pressure. When the busbar cools and contracts, decreasing its thickness, the disc spring 251 releases its elasticity, pushing the voltage component 250 outward to follow the surface of the busbar. The compression of the disc spring 251 changes from half its stroke to zero compression. Within this range, the decrease in elastic force is also gradual, maintaining sufficient contact pressure and preventing gaps or incomplete connections at the contact surface. Thus, regardless of whether the busbar undergoes thermal expansion or contraction, the conductive contact pressure always fluctuates slightly around its initial value, maintaining a stable and reliable conductive contact state over a long period.

[0034] The complete installation and operation process of this cable branch box busbar installation structure is as follows: During the installation phase, the operator holds the handle 23 at the tail of the first clamp 21 and the second clamp 22, applies inward force to press the handle 23, using the central hinge shaft as a fulcrum to overcome the torsional torque of the torsion spring, causing the clamping ends of the two clamps to open outward. The isolation components 24 and contact components 25 on both sides open synchronously with the clamps to an opening greater than the thickness of the busbar. Then, the busbar clamp 2 is aligned with the preset installation point on the busbar, and the handle 23 is slowly released. The torsion spring begins to release its torsional torque, driving the two clamps to close towards each other. During the closing process, the guide slope at the end of the sleeve 242 first contacts the side of the busbar, guiding the sleeve 242 to automatically align and slide in, allowing the busbar to gradually enter between the opposing working surfaces of the contact components 25 on both sides. As the grippers continue to close, the working surface of the voltage component 250 first contacts the side wall of the busbar. The reaction force of the busbar pushes the voltage component 250 back into the housing 242, and the disc spring 251 is gradually compressed. When the grippers are fully closed, the end faces of the two housings 242 are completely against the side walls of the busbar. The entire clamping torque of the torsion spring is transmitted to the housing 242 through the grippers, support rod 240, and support plate 241. The housing 242 bears all the mechanical clamping load, completing the mechanical fixation of the busbar clamp 2. At this time, the voltage component 250 is compressed to a position where the working surface is flush with the end face of the housing 242. The disc spring 251 is in a half-compression state with half of its rated total stroke, continuously applying stable elastic pressure to the voltage component 250, so that the working surface of the voltage component 250 is tightly attached to the surface of the busbar, completing the construction of conductive contact. Finally, the branch cable terminal is fixed to the connector at the end of the busbar clamp 2, thus completing the assembly of the tap changer circuit.

[0035] During the heating phase of operation, when the busbar 11 generates heat due to the energized load, its thickness undergoes thermal expansion and deformation. The side walls of the busbar expand outward, pushing against the voltage components 250 on both sides. At this time, the housing 242 is already pressed against the surface of the busbar, maintaining a relatively fixed position. Under the pushing force of the busbar, the voltage components 250 slide along the guide groove 260 into the housing 242, further compressing the disc spring 251. During this process, the expansion of the busbar is entirely absorbed by the compression stroke of the disc spring 251, and the opening and closing angle of the gripper changes only slightly. The torque increase of the torsion spring is significantly weakened, and the increased stress of the torsion spring is entirely borne by the insulating housing 242 and will not be transmitted to the conductive contact surface. At the same time, since the disc spring 251 is in the working range with a gentle force characteristic, the increase in elastic force due to the increase in compression is minimal. The contact pressure of the voltage component 250 on the busbar remains basically unchanged, maintaining a tight and conductive contact. This avoids the problem of thermal expansion leading to a sharp increase in clamping force and accelerated torsion spring fatigue, as seen in traditional structures.

[0036] During the cooling phase, when the busbar 11 cools down due to power failure or reduced load, its thickness undergoes cold contraction deformation. The side walls of the busbar contract inwards, reducing the reverse thrust on the voltage component 250. At this time, the disc spring 251 begins to release elastically, pushing the voltage component 250 to slide along the slide groove 260 towards the busbar, always following the contraction displacement of the busbar to ensure the working surface continuously presses against the busbar surface. During this process, the compression of the disc spring 251 gradually decreases from a semi-compressed state, but due to the smooth force characteristics within the working range, the decrease in elastic force is very limited, still providing sufficient contact pressure and preventing gaps or incomplete connections at the contact surface. Simultaneously, the opening and closing angle of the grippers remains essentially unchanged, the output torque of the torsion spring does not drop significantly, and the reliability of the mechanical fixation is not affected by the busbar contraction.

[0037] During long-term operation, even if the torsion spring experiences slight elastic creep and torque decay, it will only slightly affect the mechanical clamping force of the housing 242 on the busbar. The conductive contact pressure is entirely provided independently by the disc spring 251 and is unaffected by the state of the torsion spring. Therefore, the reliability of the conductive contact will not decrease with the aging of the torsion spring. At the same time, normal wear of the contact surface can be automatically compensated by the rebound extension of the disc spring 251, maintaining a stable contact pressure at all times without the need for on-site tightening and adjustment, which greatly reduces the workload of operation and maintenance and the frequency of power outages for repairs.

[0038] In summary, this structure, through the functional separation design of the isolation component 24 and the contact component 25, combined with the bidirectional compensation structure of the disc spring 251 in its semi-compressed initial state, retains the advantages of traditional hanging-type busbar clamps 2, such as no drilling and quick installation, while fundamentally solving the defects of poor thermal expansion and contraction adaptability, unstable contact pressure, and easy overheating of joints caused by the linkage between the torsion spring torque and the clamp angle. This significantly improves the operational reliability and service life of the cable branch box busbar T-connection structure. Example 2 This embodiment, based on the content provided in Embodiment 1, aims to provide a busbar installation structure for a cable branch box. The specific steps are as follows: Step 1: The operator holds the handle 23 at the tail of the first gripper 21 and the second gripper 22, and applies inward force to overcome the torsional torque of the torsion spring, so that the two grippers rotate relative to each other around the central hinge axis, which drives the isolation component 24 and the contact component 25 at the gripping end of the two grippers to open outward synchronously until the opening width is greater than the thickness of the busbar 11, thus completing the pre-opening preparation before clamping; Step 2: Align the opened busbar clamp 2 with the predetermined clamping position on the busbar 11, and slowly release the handle 23. The torsion spring releases the torsional torque to drive the two clamping claws to rotate towards each other and close. During the closing process, the guide slope at the end of the sleeve 242 first contacts the side of the busbar 11, guiding the sleeve 242 to automatically align and slide in, so that the busbar 11 gradually enters between the relative working surfaces of the two side contact components 25. Step 3: As the grippers continue to close, the working surface of the voltage component 250 first contacts the side wall of the busbar 11. The reaction force of the busbar 11 pushes the voltage component 250 back into the housing 242, simultaneously compressing the disc spring 251. When the grippers are fully closed, the end faces of the two housings 242 are completely against the two side walls of the busbar 11. The entire clamping torque of the torsion spring is transmitted to the housing 242 through the grippers, support rod 240, and support plate 241, and the housing 242 bears the entire mechanical clamping force. The load is held to complete the mechanical fixing of the busbar clamp 2; at this time, the voltage component 250 is compressed to the position where the working surface is flush with the end face of the housing 242, and the disc spring 251 is in a half-compression state of half of the rated total stroke, continuously applying stable elastic pressure to the voltage component 250, so that the working surface of the voltage component 250 is tightly attached to the surface of the busbar 11, completing the construction of conductive contact; finally, the branch cable terminal is fixed on the connector at the end of the busbar clamp 2, thus completing the tapping assembly of a single set of busbar clamp 2; Step 4: After the busbar clamp 2 is put into operation, when the busbar 11 generates heat due to the energized load and undergoes thermal expansion deformation in the thickness direction, the two side walls of the busbar 11 expand outward and push the voltage components 250 on both sides in the opposite direction. At this time, the position of the housing 242 remains relatively fixed, and the voltage component 250 slides into the housing 242 along the guide groove 260, compressing the disc spring 251. The expansion of the busbar is completely absorbed by the compression stroke of the disc spring 251. The compression of the disc spring 251 varies between half of the rated stroke and the maximum value. Its output elastic force increase is suppressed within a very small range. The voltage component 250 always maintains a tight fit with the surface of the busbar 11, and the stress increased by the torsion spring is entirely borne by the insulating housing 242, which will not aggravate the fatigue attenuation of the torsion spring. When the busbar 11 experiences a temperature drop due to power failure or reduced load, and undergoes cold contraction deformation in the thickness direction, the two side walls of the busbar 11 contract inward, reducing the reverse thrust on the voltage component 250. The disc spring 251 releases elastically and pushes the voltage component 250 to slide and extend along the slide groove 260 towards the busbar 11. The compression of the disc spring 251 varies between half of the rated stroke and zero, and the decrease in elastic force remains gradual. The working surface of the voltage component 250 continuously presses against the surface of the busbar 11, maintaining an effective conductive contact area. During long-term operation, even if the torsion spring experiences slight elastic creep and torque decay, it will only slightly affect the mechanical clamping force of the sleeve 242 on the busbar. The conductive contact pressure is always provided independently by the disc spring 251, unaffected by the state of the torsion spring, and the normal wear of the contact surface can also be automatically compensated by the rebound of the disc spring 251. Therefore, the voltage component 250 can adapt to the thickness deformation caused by the thermal expansion and contraction of the busbar 11, and the elastic force of the disc spring 251 always fluctuates bidirectionally around the halfway point of the rated stroke, so that the conductive contact pressure remains basically constant over a long period of time.

[0039] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A cable branch box, comprising a box body (1), wherein multiple busbars (11) are provided inside the box body (1), busbar clamps (2) are clamped and connected to the busbars (11), and the ends of the busbar clamps (2) are connected to connectors for electrical connection with external lines, characterized in that: The bus clamp (2) includes a first clamping jaw (21) and a second clamping jaw (22). The first clamping jaw (21) and the second clamping jaw (22) are rotatably connected by a torsion spring. The tail ends of the first clamping jaw (21) and the second clamping jaw (22) away from the clamping end are provided with handles (23). The handles (23) are used to drive the two clamping jaws to open against the torsion spring torque, so as to realize the installation and removal of the bus clamp on the busbar. Isolation components (24) are fixedly provided on the clamping sides of the first jaw (21) and the second jaw (22). The two isolation components (24) are arranged opposite to each other. Each isolation component (24) is movably provided with a pressing component (25). The pressing component (25) can reciprocate and extend within the isolation component (24) along the clamping direction of the busbar (11). When the busbar clamp (2) is held in the busbar (11), the working surfaces of the two side contact components (25) are pressed against the two side walls of the busbar (11). The isolation component (24) bears the mechanical clamping load transmitted by the gripper. The contact component (25) can adapt to the thickness deformation caused by thermal expansion and contraction of the busbar (11) and always maintain a tight conductive contact with the surface of the busbar.

2. The cable branch box according to claim 1, characterized in that: The isolation component (24) includes two support rods (240), which are fixedly connected to the clamping sides of the first clamp (21) and the second clamp (22) respectively. The two support rods (240) are fixedly connected to each other by a support plate (241). A sleeve (242) is fixedly provided on the side of the support plate (241) facing the busbar (11). The sleeves (242) of the two isolation components (24) are arranged opposite to each other, and a pressure contact component (25) is slidably connected inside each sleeve (242).

3. The cable branch box according to claim 2, characterized in that: The casing (242) has a U-shaped frame structure with a groove in the center for accommodating the touch component (25). The U-shaped frame provides circumferential limiting for the extension and retraction displacement of the touch component (25).

4. The cable branch box according to claim 2, characterized in that: The housing (242) is made of insulating and flame-retardant material to bear the mechanical clamping load transmitted by the gripper and to achieve electrical isolation between the gripper and the contact component (25), so that the mechanical bearing force and the conductive contact force are separated from each other.

5. The cable branch box according to claim 2, characterized in that: The outer wall of the casing (242) is set in a trapezoidal structure. The two casings (242) are provided with guide slopes near the two ends on opposite sides. The guide slopes are used to guide the casing (242) to smoothly enter the clamping position when the busbar clamp (2) is inserted into the busbar row (11).

6. The cable branch box according to claim 2, characterized in that: The pressure-sensitive assembly (25) includes a voltage element (250), which is slidably fitted inside the housing (242). The voltage element (250) and the support plate (241) are elastically connected by a plurality of disc springs (251). The disc springs (251) are housed inside the housing (242), and their elastic force direction is perpendicular to the surface of the busbar (11).

7. The cable branch box according to claim 6, characterized in that: The voltage component (250) is made of a copper alloy material with high conductivity, and its surface facing the busbar (11) is the working surface, which is used to form a conductive contact with the surface of the busbar (11) in the clamping state.

8. The cable branch box according to claim 6, characterized in that: The outer wall of the voltage component (250) is provided with a slider (26), and the inner wall of the housing (242) is provided with a corresponding groove (260). The slider (26) is slidably connected inside the groove (260) to constrain the voltage component (250) to slide back and forth only in a direction perpendicular to the surface of the busbar (11).

9. The cable branch box according to claim 6, characterized in that: When the disc spring (251) is in a free state, it pushes the working surface of the voltage component (250) beyond the end face of the housing (242). When the busbar clamp (2) is clamped on the busbar (11), the voltage component (250) is pushed into the housing (242) by the busbar (11) until the working surface of the voltage component (250) is flush with the end face of the housing (242). At this time, the compression of the disc spring (251) is half of its rated total stroke, and it has a bidirectional extension compensation margin.

10. The cable branch box busbar installation structure according to claim 1, characterized in that: The cable branch box as described in any one of claims 1-9, Includes the following steps: S1: Hold the handle (23) at the tail of the first gripper (21) and the second gripper (22) to overcome the torsion spring torque and make the two grippers rotate relative to each other, thereby causing the isolation component (24) and the contact component (25) at the gripping end of the two grippers to separate and open. S2: Align the two open jaws with the predetermined clamping position of the busbar (11), release the handle (23), and the torsion spring rebounds to drive the two jaws to rotate in opposite directions, so that the end faces of the housings (242) of the two isolation components (24) abut against the two side surfaces of the busbar (11) respectively, forming a mechanical limit; S3: During the process of the housing (242) abutting against the busbar (11), the voltage component (250) is pushed into the housing (242) by the surface of the busbar (11), compressing the disc spring (251) until the working surface of the voltage component (250) is flush with the end face of the housing (242), and the disc spring (251) is compressed to half of the rated stroke, so that the voltage component (250) is pressed against the surface of the busbar (11) with constant elastic pressure, thus completing the clamping and installation of the busbar clamp (2); S4: When the busbar (11) expands in the thickness direction due to heat generated by energization, the two sides of the busbar (11) push the voltage component (250) outward. The voltage component (250) compresses the disc spring (251) along the inner wall of the housing (242). The compression of the disc spring (251) varies between half of the rated stroke and the maximum value. Its output elastic force increase is suppressed within the preset range. The voltage component (250) always keeps in close contact with the surface of the busbar (11). When the busbar (11) shrinks in the thickness direction due to power failure and cooling, the disc spring (251) is released elastically and pushes the voltage element (250) to slide towards the busbar (11). The compression varies between half of the rated stroke and zero. The working surface of the voltage element (250) continuously presses against the surface of the busbar (11) to maintain an effective conductive contact area. Therefore, the voltage component (250) adapts to the thickness deformation caused by the thermal expansion and contraction of the busbar (11), and the elastic force of the disc spring (251) always fluctuates bidirectionally around half of the rated stroke, so that the contact pressure remains basically constant.

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