A photovoltaic fuse

Abstract

The application discloses a photovoltaic fuse in the technical field of fuses, which comprises a base, a cover plate and a detachable fuse body, further comprises an elastic sheet, the elastic sheet is fixedly installed in the inner cavity of the base, a clamping driving element is arranged on the cover plate, the clamping driving element has a wedge guide surface, a locking matching structure is arranged between the cover plate and the base, the locking matching structure is used for locking the cover plate at an assembly position, maintaining the compression and clamping force of the elastic sheet on the fuse body, the supply body of the clamping force of the fuse body is replaced by the elastic restoring force of the elastic sheet itself to the rigid wedge extrusion force provided by the clamping driving element, the elastic sheet only relies on the elastic force to maintain the open gap in the non-assembly state, and no longer bears the continuous pre-tightening bending stress for a long time, so that the occurrence premise of stress relaxation and elastic fatigue of copper alloy materials in a high-temperature environment is fundamentally avoided, and the failure mode of the traditional integrated contact that relies on the elastic sheet pre-deformation to provide the clamping force is completely changed.

Description

Technical Field

[0001] This invention relates to the field of fuse technology, specifically a photovoltaic fuse. Background Technology

[0002] Photovoltaic fuses are the core components of photovoltaic DC systems for overcurrent protection and fault branch isolation. They consist of a fuse element and a matching fuse base. The elastic contact inside the base serves both as a fuse element clamp and a conductor. Most existing photovoltaic fuses use an integrated copper alloy spring structure for their elastic contacts, relying on the bending deformation of the spring itself to provide clamping force. The clamping working surface is plated with tin or silver to reduce contact resistance and improve weather resistance.

[0003] However, during long-term outdoor service, this structure exhibits two significant defects: 1. The integrated spring clip simultaneously carries current and provides elastic clamping. It is under bending stress for a long time. Combined with the outdoor high temperature environment and the cyclic load of repeated insertion and removal, it is prone to stress relaxation and elastic fatigue, which leads to irreversible decay of clamping force, resulting in increased contact resistance, abnormal temperature rise, and even DC arcing and electrical fire. 2. During insertion and removal, the spring clip clamping surface and the fuse end cap are in surface contact sliding friction. After repeated insertion and removal, the plating layer is easily worn off, and the exposed copper substrate is easily oxidized and corroded, which further deteriorates the contact performance and shortens the service life of the base.

[0004] Existing improvements mainly focus on replacing high-performance elastic materials and thickening the coating, which can only slow down the rate of degradation. They cannot solve the fundamental problems of coupling current carrying and elastic functions and large wear during insertion and removal from the structural root. Long-term service reliability still has obvious shortcomings. Summary of the Invention

[0005] The purpose of this invention is to provide a photovoltaic fuse to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a photovoltaic fuse, comprising a base, a cover plate, and a detachable fuse element. The base is provided with an inner cavity for accommodating the fuse element and also includes a spring clip. The spring clip is fixedly installed in the inner cavity of the base. The side of the spring clip facing the fuse element is a clamping working surface, and the side facing away from the fuse element is a pressure-bearing back surface. The spring clip is configured such that, in the non-locking state where the cover plate is not fully assembled, the spring clip maintains an assembly gap between its clamping working surface and the metal end cap of the fuse element by relying on its own elastic restoring force. A clamping drive is disposed on the cover plate and has a wedge guide surface; The clamping drive is configured such that when the cover plate and the base are assembled in place, the clamping drive wedges into the pressure-bearing back side of the spring piece, and squeezes the pressure-bearing back side of the spring piece through the wedge guide surface, driving the spring piece clamping working surface to abut against the metal end cap of the fuse to form an electrical connection. A locking mechanism is provided between the cover plate and the base to lock the cover plate in the assembly position and maintain the clamping force of the spring on the fuse.

[0007] Preferably, the clamping drive is configured such that when the cover plate and the base are assembled in place, the side of the clamping drive away from the spring sheet abuts against the inner wall of the base, providing rigid reaction force support for the compression spring sheet.

[0008] Preferably, the spring and the clamping drive are provided in two sets and correspond one to one, with the two sets of springs symmetrically arranged on the outer sides of both ends of the fuse.

[0009] Preferably, a pressing part is slidably disposed in the inner cavity of the base along the clamping direction. The pressing part is located on the pressure-receiving back side of the spring piece. The clamping drive member presses the pressing part towards the pressure-receiving back side of the spring piece, so that the spring piece abuts against the fuse.

[0010] Preferably, the contact position between the inner wall of the base and the clamping drive is a conductive component, a pressing part is provided between the inner wall of the base and the clamping drive, and a wedge guide surface is also provided on the side of the clamping drive near the pressing part.

[0011] Preferably, the pressing part is a grid structure.

[0012] Preferably, the inner cavity of the base is provided with a base, the base is fastened with an installation carrier, and the pressing part is disposed on the installation carrier.

[0013] Preferably, the wedge guide surface is an inclined or arc-shaped guide surface, and its thickness gradually changes along the assembly direction of the cover plate.

[0014] Preferably, the locking mechanism is a snap-locking mechanism or a threaded locking mechanism.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. Eliminate the hidden danger of clamping force attenuation caused by stress relaxation from the root cause of the force; This solution replaces the main source of clamping force of the fuse body with the elastic restoring force of the spring itself to the rigid wedging and squeezing force provided by the clamping drive component; The spring only relies on its own elasticity to maintain the opening gap in the non-assembled state, and no longer bears continuous pre-tightening bending stress for a long time. This fundamentally avoids the premise of stress relaxation and elastic fatigue of copper alloy materials under high temperature environment, and completely changes the failure mode of traditional integrated contacts that rely on spring pre-deformation to provide clamping force.

[0016] 2. Significantly improved long-term stability of clamping force; the clamping force required for clamping is guaranteed by the rigid geometric structure of the clamping drive component, and the continuous extrusion force is provided by the structural rigidity support after assembly; compared with elastic recovery force, which depends on the elastic properties of materials and is prone to decay with time and temperature, this rigid extrusion force is more stable and less affected by ambient temperature and service time, and can maintain stable contact pressure between the spring and the fuse end cap for a long time, ensuring the long-term reliability of electrical connection and effectively reducing the risk of DC arcing and overheating fire.

[0017] 3. No sliding insertion and removal, effectively protecting the surface plating; during the insertion and removal of the fuse, there is always an assembly gap between the spring and the end cap, with no relative sliding friction, avoiding wear and peeling of the plating, maintaining long-term low contact resistance conductivity, and adapting to complex outdoor corrosive environments.

[0018] 4. Uniform force transmission and stable and reliable clamping; the pressing part transmits the extrusion force, converting the concentrated force of the driving component into a surface load, avoiding local stress concentration and uneven deformation of the spring sheet; the wedge-in guide surface and locking structure ensure smooth assembly, and the clamping force does not decrease after locking, with vibration resistance suitable for outdoor photovoltaic applications. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention in the locked state; Figure 2 This is a schematic diagram of the overall structure of the present invention in the non-locked state; Figure 3 This is a schematic diagram of the overhead sectional view of the present invention in the locked state; Figure 4 for Figure 3 Enlarged schematic diagram of the structure at point A in the middle; Figure 5 This is a schematic diagram of the front sectional view of the structure of the present invention in the locked state; Figure 6 This is an exploded view of the structure of the present invention; Figure 7 A schematic diagram of the mounting carrier and its press-fitting part; Figure 8 A schematic diagram of the internal structure of the base cavity when transitioning from the unlocked state to the locked state; Figure 9 for Figure 8 Enlarged schematic diagram of the structure at point B; Figure 10 for Figure 8 Enlarged schematic diagram of the structure at point C; Figure 11 Flowchart for inserting clamping drive components without pressure fitting.

[0020] The attached diagram lists the components represented by each number as follows: 1. Base, 2. Cover plate, 3. Fuse, 4. Spring, 5. Clamping drive, 6. Pressing part, 7. Base, 8. Mounting carrier, 9. First direction X. Detailed Implementation

[0021] Please see Figure 1-11 The present invention provides a technical solution: like Figure 1-3 As shown in Figure 8, the photovoltaic fuse described in this embodiment includes a base 1, a cover plate 2, and a fuse element 3. The base 1 has an inner cavity for receiving, and the fuse element 3 can be inserted into the inner cavity for assembly. Two spring pieces 4 are symmetrically fixed at both ends of the inner cavity of the base 1. The root of the spring piece 4 is fixed to the inner wall of the base 1 by riveting or snapping. The side of the spring piece 4 facing the fuse 3 is the clamping working surface, and the surface is plated with a conductive coating to abut against the fuse 3 and form an electrical connection. The side facing away from the fuse 3 is the pressure back side, which is used to accept the pressure so that the spring piece 4 abuts against the fuse 3. This changes the traditional assembly method that uses the elastic force generated by the deformation of the spring 4 to keep the spring 4 and the fuse 3 in contact. As a result, the elastic decay of the spring 4 no longer affects the contact pressure between the spring 4 and the fuse 3. This avoids the situation where the contact pressure between the spring 4 and the fuse 3 decreases when the performance of the spring 4 deteriorates, which would lead to an increase in the connection resistance between the spring 4 and the fuse 3 and thus cause the temperature rise at the connection point of the spring 4 and the fuse 3 to be too high. In the unlocked state where the cover plate 2 is not closed, the spring piece 4 maintains its free posture of opening outwards by relying on its own elastic restoring force. At this time, the distance between the clamping working surfaces of the spring pieces 4 on both sides is greater than the total length of the fuse 3. A certain assembly gap is formed between the clamping working surfaces and the metal end caps at both ends of the fuse 3. When the fuse 3 is installed into the base 1, it does not contact or rub against the spring piece 4 and will not scratch the plating. In traditional assembly methods, the spring plate 4 is used to hold the fuse 3 with its elastic force. During the installation of the fuse 3, the fuse 3 must squeeze the spring plate 4, causing the spring plate 4 to deform and generate sufficient elastic force to maintain sufficient contact pressure between the spring plate 4 and the fuse 3. This results in sliding friction with a certain friction force between the fuse 3 and the spring plate 4 during the installation process. As a result, when the fuse 3 is replaced repeatedly, the surface plating of the spring plate 4 is easily damaged to a certain extent. In this invention, when the fuse 3 is replaced, a certain assembly gap is formed between the clamping working surface and the metal end caps at both ends of the fuse 3, eliminating relative sliding friction, avoiding plating wear and peeling, maintaining long-term low contact resistance conductivity, and adapting to complex outdoor corrosive environments. Two clamping drive components 5 are fixed to the inner surface of the cover plate 2 corresponding to the two spring pieces 4. The clamping drive component 5 is a wedge-shaped block structure, and a wedge guide surface is provided on the side facing the spring piece 4. The wedge guide surface is along the assembly direction of the cover plate 2. Figure 2The thickness gradually changes in the vertical direction; when the cover plate 2 is closed downwards and assembled with the base 1, the clamping drive 5 is simultaneously inserted into the gap between the pressure back of the spring 4 and the inner wall of the base 1, and the wedge guide surface gradually squeezes the free end of the spring 4, driving the spring 4 to undergo elastic deformation towards the fuse 3 side, and finally making the clamping working surface tightly pressed on the metal end cap of the fuse 3, forming a reliable electrical connection; at this time, the clamping pressure on the fuse is provided by the rigid wedge extrusion force of the clamping drive 5; The clamping force required for clamping is rigidly guaranteed by the geometric structure of the clamping drive component, and the continuous extrusion force is provided by the structural rigidity support after assembly. Compared with the elastic recovery force, which depends on the elastic properties of the material and is prone to decay with time and temperature, the rigid extrusion force is more stable and less affected by ambient temperature and service time. It can maintain a stable contact pressure between the spring and the fuse end cap for a long time, ensuring the long-term reliability of the electrical connection and effectively reducing the risk of DC arcing and overheating fire. The cover plate 2 and the base 1 are provided with a locking engagement structure (such as snap-locking, screw locking, etc.). After locking, the position of the cover plate 2 is fixed, and the clamping drive 5 continuously maintains the squeezing state to ensure stable clamping force and is not affected by vibration, temperature difference deformation.

[0022] like Figure 11 The side edge a of the insertion surface of the spring piece 4 relative to the clamping drive 5 is generally not specially chamfered. This causes the adjacent surfaces of the clamping drive 5 and the spring piece 4 to be easily subjected to the cutting action of the edge a when the clamping drive 5 is inserted. After repeated installation, the dimensional accuracy of the clamping drive 5 cannot be effectively maintained under the cutting action, which causes the contact state of the spring piece 4 with the fuse 3 to fail. Based on the above problems, this embodiment preferably adds a force transmission pressing structure to further improve the dimensional stability of the clamping drive component 5 and the uniformity of the force on the spring sheet; At both ends of the inner cavity of the base 1 and on the outer side of the spring 4, a pressing part 6 is slidably installed in a direction perpendicular to the axial direction of the fuse body 3. The pressing part 6 is a grid-type plate structure, with one side attached to the pressure-bearing back of the spring 4 and the other side cooperating with the clamping drive part 5. Since there is a connection resistance at the connection between the spring 4 and the fuse 3, this location is generally the area in the fuse where the temperature rise is more serious. Therefore, a grid-type plate structure is adopted to enable the spring 4 to dissipate heat well and to avoid the two ends of the spring 4 being wrapped by the fuse and the pressing part 6 at the same time, which would prevent effective heat dissipation. refer to Figure 3 and 8A wedge guide surface is provided on one side of the clamping drive 5 that cooperates with the pressing part 6, and a matching inclined surface is provided on the corresponding side of the pressing part 6. When the cover plate is closed, the clamping drive 5 wedges downward, and the vertical closing force is converted into a horizontal extrusion force through the inclined surface cooperation, pushing the pressing part 6 to slide towards the spring 4 side, thereby uniformly extruding the entire back of the spring 4, so that the spring 4 clamping working surface is in complete contact with the end cover of the fuse 3. This ensures that during the insertion of the clamping drive 5, there will be no friction between the component and the edge a of the spring 4, thus preventing damage to the fuse components from the edge a. Figure 11 As shown, the pressing process of the spring clip 4 clamping the working surface towards the end cap of the fuse body 3 is a whole-body translational pressing under the action of the pressing part 6, which avoids the edge a pressing the end cap of the fuse body 3 first, causing the end cap of the fuse body 3 to break. The base 1 has a fixed base 7 in its inner cavity. An independent mounting carrier 8 is fastened to the base 7. The pressing part 6 is slidably assembled on the mounting carrier 8 through a sliding groove structure to form a modular component. It can be pre-assembled and then installed into the base as a whole, which improves the production assembly efficiency and also reduces the structural complexity of individual parts, thereby reducing the processing difficulty of each component.

[0023] In order to prevent the clamping drive 5 from deforming due to long-term unilateral pressure (on the side of the spring piece 4) after insertion, in this embodiment, the clamping drive 5 is preferably configured such that when the cover plate 2 and the base 1 are assembled in place, the side of the clamping drive 5 away from the spring piece 4 abuts against the inner wall of the base 1, providing rigid reaction force support for the clamping drive 5 to squeeze the spring piece 4. Furthermore, the contact points between the base 1 and the clamping drive 5 are mostly conductive parts. To facilitate the insertion of the clamping drive 5, it is inconvenient to add insulation at these points. Since the conductive parts are generally stamped parts, the corresponding position relative to the insertion surface of the clamping drive 5 also experiences the cutting action of the aforementioned spring 4's edge a on the clamping drive 5. Therefore, the contact point between the inner wall of the base 1 and the clamping drive 5 is a conductive component. A pressing part 6 is provided between the inner wall of the base 1 and the clamping drive 5. A wedge guide surface is also provided on the side of the clamping drive 5 near the pressing part 6. The pressing part 6 is directly fixedly connected to the mounting carrier 8, protecting the clamping drive 5 and dissipating heat from the conductive components.

[0024] Preferably, the locking mechanism is a snap-locking mechanism or a threaded locking mechanism.

Claims

1. A photovoltaic fuse, comprising a base (1), a cover plate (2), and a detachable fuse element (3), wherein the base (1) is provided with an inner cavity for accommodating the fuse element (3), characterized in that, Also includes: The spring (4) is fixedly installed in the inner cavity of the base (1). The side of the spring (4) facing the fuse (3) is the clamping working surface, and the side facing away from the fuse (3) is the pressure-bearing back surface. The spring (4) is configured such that when the cover plate (2) is not assembled in the non-locked state, the spring (4) relies on its own elastic restoring force to maintain an assembly gap between its clamping working surface and the metal end cap of the fuse (3). A clamping drive (5) is disposed on the cover plate (2) and has a wedge guide surface; The clamping drive (5) is configured such that when the cover plate (2) and the base (1) are assembled in place, the clamping drive (5) wedges into the pressure back side of the spring (4) and squeezes the pressure back side of the spring (4) through the wedge guide surface, causing the spring (4) to clamp the working surface to abut against the metal end cap of the fuse (3) to form an electrical connection. A locking mechanism is provided between the cover plate (2) and the base (1) to lock the cover plate (2) in the assembly position and maintain the clamping force of the spring piece (4) on the fuse (3).

2. The photovoltaic fuse according to claim 1, characterized in that: The clamping drive (5) is configured such that when the cover plate (2) and the base (1) are assembled in place, the side of the clamping drive (5) away from the spring (4) abuts against the inner wall of the base (1) to provide rigid reaction force support for the compression spring ((4)).

3. The photovoltaic fuse according to claim 1, characterized in that: The spring (4) and the clamping drive (5) are provided in two sets and correspond one to one. The two sets of springs (4) are symmetrically arranged on the outer sides of both ends of the fuse (3).

4. The photovoltaic fuse according to claim 1 or 2, characterized in that: In the inner cavity of the base (1), a pressing part (6) is slidably provided along the clamping direction. The pressing part (6) is located on the pressure-bearing back side of the spring (4). The clamping drive (5) presses the pressing part (6) toward the pressure-bearing back side of the spring (4) so ​​that the spring (4) abuts against the fuse (3).

5. The photovoltaic fuse according to claim 2, characterized in that: The contact position between the inner wall of the base (1) and the clamping drive (5) is a conductive component. A pressing part (6) is provided between the inner wall of the base (1) and the clamping drive (5). A wedge guide surface is also provided on the side of the clamping drive (5) near the pressing part (6).

6. The photovoltaic fuse according to claim 4 or 5, characterized in that: The pressing part (6) is a grid structure.

7. The photovoltaic fuse according to claim 6, characterized in that: The base (1) has a base (7) inside its cavity, and the base (7) is fastened to an installation carrier (8). The pressing part (6) is disposed on the installation carrier (8).

8. The photovoltaic fuse according to claim 6, characterized in that: The wedge guide surface is an inclined or arc-shaped guide surface, and its thickness gradually changes along the assembly direction of the cover plate (2).

9. The photovoltaic fuse according to claim 1, characterized in that: The locking mechanism is either a snap-locking mechanism or a threaded locking mechanism.

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