An alloy thermal fuse for fast-blow LED lamps

Abstract

The present invention provides an alloy-type thermal fuse for rapid melting of LED lamps. The thermal fuse comprises a housing with trapezoidal wedges disposed on either side of the inner wall of the housing's marking surface. Two leads are inserted between the two trapezoidal wedges and the inner wall of the housing's mounting surface. One end of the two leads is welded together by a thermal element, and flux is applied around the periphery of the thermal element. One side of the thermal element directly contacts the inner wall of the housing's mounting surface, while the other ends of the leads extend out of the housing. The housing's opening is sealed with epoxy resin glue. A guide surface is provided on the upper portion of the trapezoidal wedge. The thickness of the trapezoidal wedge varies with the width of the housing's interior space and the diameter of the leads. The width of the trapezoidal wedge should ensure that the two leads are positioned after insertion into the housing. The thermal fuse utilizes a housing with a trapezoidal wedge having a sloped guide surface for securing the leads. The bottom of the thermal element within the housing can contact the inner wall of the mounting surface. Heat energy absorbed by the thermal fuse's mounting surface causes the thermal element to rapidly melt with the aid of the flux.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal-link manufacturing, and in particular to an alloy-type thermal-link for fast-blow LED lamps. Background Art

[0002] Currently, when using existing T8 series LED lamps, the 220V bridge rectifier chip diodes can rapidly heat up under circuit anomalies. When the temperature rise of the bridge rectifier chip diodes reaches a certain value, it can affect the normal operation of the entire LED lamp circuit board and, in severe cases, cause the LED circuit board to catch fire. The working principle of a thermal link is that the heat energy from the diode is transferred to the thermal adhesive, which then transfers the heat to the mounting surface of the housing. The mounting surface then transfers the heat to the thermal element. The heated thermal element, under the action of the flux, melts, thus protecting the LED lamp from accidents or fire. The temperature protection alloy thermal links used in the prior art have uncertain mounting positions of the temperature-sensing thermal element within the housing. Some are in direct contact with the inner wall of the housing mounting surface, some are in direct contact with the inner wall of the housing marking surface, and some are suspended in the housing. This makes it difficult for the thermal element to accurately and quickly sense changes in the housing temperature on the mounting surface side. Furthermore, the diameter of the temperature-sensing thermal element, the diameter and material of the lead wires, the thermal conductivity of the housing, and the thermal conductivity of the epoxy resin adhesive all affect the thermal link's ultimate fusing effect.

[0003] Under existing technology, the thermal element's position within the housing is uncertain, resulting in irregular heat absorption paths and a wide variation in its temperature-sensing performance. Generally, a high-performance thermal link will open when the diode surface temperature exceeds its rated operating temperature by 20°C. A low-performance thermal link will not open regardless of the diode surface temperature.

[0004] An alloy thermal link (CN210897130U) for fast-blow LED lamps has the following technical problems: 1. The epoxy resin adhesive used for sealing cures at room temperature, which takes a long time to cure. During this process, the thermal element easily separates from the mounting surface, making the production process difficult to control and resulting in a low pass rate in the finished product.

[0005] An alloy thermal link (CN105428179B) with a high current resistance to disconnection has the following technical issues: 1. The two U-shaped positioning grooves separate the thermal element from the housing. When heat energy absorbed by the leads is transferred to the thermal element, the temperature of the thermal element rises rapidly and melts. Since the leads conduct heat energy, while the housing dissipates it, the thermal element only takes a few seconds to melt.

[0006] A high-temperature, aging-resistant alloy thermal link (CN104576253B) features a heat-conducting housing and leads, with the mounting surface conducting heat and the leads dissipating it. Suitable for use in electric fans and low-frequency transformers, the thermal link's power consumption ranges from over ten watts to several dozen, yet its temperature rises at only a few degrees per minute. The thermal link absorbs a negligible portion of the heat absorbed by the heating element. Summary of the Invention

[0007] The present invention aims to provide a fast-acting alloy thermal link for LED lamps. The technical problem addressed by the present invention is to ensure that the thermal link can quickly blow when the surface temperature of the diode exceeds the rated operating temperature by 20°C, without adding any new production steps.

[0008] The present invention's design principles are as follows: 1. The thermal link incorporates two trapezoidal wedges with sloped guide surfaces for securing the leads. The two trapezoidal wedges secure a thermal element, welded between the two leads, to the side of the identification surface on the bottom of the housing, ensuring contact between the thermal element and the inner wall of the mounting surface. Flux is placed around the thermal element. When an abnormality in the LED lamp circuit causes a rapid rise in the surface temperature of the rectifier diode, the temperature of the thermal link's mounting surface, which is in direct contact with the diode's outer surface, also rises. Heat energy absorbed by the thermal link's mounting surface is directly transferred to the thermal element and the leads. When the thermal element's temperature reaches its rated operating temperature, the melted flux aids in its rapid melting, protecting the circuit. Simultaneously, the portion of the leads within the housing that directly contacts the mounting surface also transfers heat energy absorbed from the mounting surface to the thermal element, accelerating its melting. The ability of the thermal element to directly absorb heat from the mounting surface and the leads within the housing is essential for the thermal link's rapid melting. Two trapezoidal wedges with sloped guide surfaces for securing the leads prevent the thermal element from being able to absorb heat directly from the mounting surface, which can occur when the leads are located in the middle of the housing opening or directly contact the inner wall of the housing's marking surface. These trapezoidal wedges also prevent the leads from absorbing heat indirectly from the mounting surface through the epoxy adhesive, which has a very low thermal conductivity. This results in the leads heating up very slowly and failing to provide the thermal element with the necessary heat to fuse. Second, the thermal conductivity of the epoxy adhesive is reduced by selecting organic fillers such as calcium carbonate and barium sulfate, which have stable high-temperature physical properties but poor thermal conductivity. This reduces the thermal conductivity of the epoxy adhesive and slows the dissipation of heat absorbed by the leads from the mounting surface. Third, the diameter and material of the leads are controlled to prevent heat absorbed by the thermal element from the mounting surface from being transferred to the outside of the housing through the leads with better thermal conductivity. 4. For LED lights using rectifier bridges, select a structure with an extended edge on the mounting surface (such as Figure 4、 Figure 5 、 Figure 6 ), the temperature sensing effect of the thermal element is better.

[0009] To achieve the above object, the technical solution of the present invention is:

[0010] An alloy thermal link for fast-blow LED lamps comprises a housing, leads, a thermal element, flux, epoxy resin adhesive, a mounting surface, a trapezoidal wedge, and an identification surface. Trapezoidal wedges are provided on either side of the inner wall of the identification surface of the housing in the thermal link. Two leads are inserted between the two trapezoidal wedges and the inner wall of the housing mounting surface. One end of the two leads is welded to the thermal element and then overlapped. The thermal element is surrounded by flux, and one side of the thermal element is in direct contact with the inner wall of the housing mounting surface. The other end of the lead extends out of the housing, and the opening of the housing is sealed with epoxy resin adhesive.

[0011] The two trapezoidal wedges in the thermal link housing are located on one side of the identification surface within the housing. A guide surface is provided on the upper portion of the trapezoidal wedges. The thickness of the trapezoidal wedges varies with the width of the housing cavity and the diameter of the lead wires. The width of the trapezoidal wedges should ensure that the two leads are positioned after being inserted into the housing.

[0012] The shell of the thermal fuse is composed of five surfaces including four surfaces and a bottom. The shell is made of PA66 material plus glass fiber or 95 porcelain containing alumina with high thermal conductivity.

[0013] The lead wire in the thermal fuse has a diameter of 0.45-0.65 mm, and the portion of the lead wire extending from the housing is covered with a Teflon insulation layer. The lead wire is made of copper-clad steel wire or tinned copper wire, and the maximum resistance per meter of the copper-clad steel wire with a diameter of 0.55 mm is 0.26 Ω. The diameter of the thermal element is 0.55-0.8 mm.

[0014] The epoxy resin glue in the thermal cutout includes the following raw materials in parts by weight:

[0015] 45-65 parts of phenolic epoxy resin, 12-20 parts of alicyclic amine, 0.2-1 part of fumed silica, 0.3-0.6 part of defoaming agent, 5-15 parts of calcium carbonate, 5-9 parts of aluminum hydroxide, and 7-16 parts of barium sulfate.

[0016] The filler particle size or coarseness of the epoxy resin glue in the thermal fuse is as follows: calcium carbonate: 2000-3000 mesh, aluminum hydroxide: 2000 mesh, barium sulfate: 2000-3000 mesh.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. This thermal link uses two trapezoidal wedges with sloped guide surfaces for fixing the leads. The two trapezoidal wedges fix the thermal element welded between the two leads to one side of the mounting surface at the bottom of the shell, ensuring that the thermal element can contact the inner wall of the mounting surface at the bottom of the shell;

[0019] 2. The thermal element in the thermal link is surrounded by flux. When an abnormality in the LED lamp circuit causes the surface temperature of the rectifier diode in the circuit to rise rapidly, the temperature of the mounting surface of the thermal link, which is in direct contact with the outer surface of the diode, also rises. The heat energy absorbed by the mounting surface of the thermal link is directly transferred to the thermal element and leads. When the temperature of the thermal element rises to the rated operating temperature, the thermal element will quickly fuse with the help of the melted flux, thereby achieving the purpose of protecting the circuit;

[0020] 3. The lead of the thermal link is located in the housing and is in direct contact with the mounting surface. It can also transfer the heat energy absorbed from the mounting surface to the thermal element and accelerate the melting of the thermal element. The ability of the thermal element to directly absorb heat energy from the mounting surface and the lead inside the housing is the fundamental guarantee for the thermal link to achieve rapid melting.

[0021] 4. The two trapezoidal wedges with sloped guide surfaces for fixing the leads of the thermal link avoid the thermal element being far away from the inner wall of the housing mounting surface and unable to directly absorb heat energy from the inner wall of the mounting surface due to the leads being located in the middle of the housing opening or the leads directly contacting the inner wall of the housing identification surface;

[0022] 5. The two trapezoidal wedges of the thermal link avoid the situation where the lead wire is located in the middle of the shell opening or directly contacts the inner wall of the shell identification surface. This will cause the lead wire to absorb heat energy indirectly from the inner wall of the shell mounting surface through the epoxy resin adhesive with extremely low thermal conductivity, resulting in an extremely slow lead wire heating rate and failure to provide the thermal element with the heat energy required for melting in a timely manner.

[0023] 6. The thermal fuse uses a thinner tinned copper wire with a diameter of 0.45-0.65mm or a copper-clad steel wire with a maximum resistance of 0.26Ω per meter when the diameter is 0.55mm. This can prevent the heat energy absorbed by the thermal element from being transferred to the outside of the shell again, making it difficult to fuse;

[0024] 7. The thermal fuse adopts epoxy resin glue with excellent sealing and heat insulation performance, which can slow down the absorption of heat energy of the lead wire in the shell and help the lead wire transfer heat energy to the thermal element;

[0025] 8. The marking surface of the thermal link shell has no direct contact with the thermal element, which can effectively slow down the heat dissipation to the thermal element;

[0026] 9. The thermal fuse limits the diameter of the thermal element, which can reduce the heat energy required to be absorbed when the thermal element melts, increase the heating rate of the thermal element, and improve the melting sensitivity of the thermal element. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 , schematic diagram of the middle cross-sectional structure of the thermal link;

[0028] Figure 2 , schematic diagram of the shell opening structure of the thermal link housing;

[0029] Figure 3 , Schematic diagram of the cross-sectional structure of the thermal link in the direction BB B;

[0030] Figure 4 , schematic diagram of the cross-sectional structure of the thermal link with extended edges as viewed in the BB direction A;

[0031] Figure 5 , schematic diagram of the cross-sectional structure of the thermal link with extended edges as viewed along AA direction;

[0032] Figure 6 , Schematic diagram of the appearance of a thermal cutout with extended edges.

[0033] In the figure: 1. housing, 2. leads, 3. thermal element, 4. flux, 5. epoxy resin glue, 6. mounting surface, 7. trapezoidal wedge, 8. identification surface. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described clearly and completely below with reference to the accompanying drawings and embodiments.

[0035] See attached Figure 1-6 In the thermal link, trapezoidal wedges 7 are provided on both sides of the inner wall of the identification surface 8 of the housing 1. Two leads 2 are respectively inserted between the two trapezoidal wedges 7 and the inner wall of the mounting surface 6 of the housing 1. One end of the two leads 2 is welded and overlapped by a thermal element 3. The thermal element 3 is surrounded by flux 4. One side of the thermal element 3 is in direct contact with the inner wall of the mounting surface 6 of the housing 1. The other end of the lead 2 extends out of the housing 1. The opening of the housing 1 is sealed with epoxy resin glue 5.

[0036] Two trapezoidal wedges 7 are located within the housing 1 of the thermal link, on one side of the inner marking surface 8 of the housing 1. A guide surface is provided on the upper portion of the trapezoidal wedges 7. The thickness of the trapezoidal wedges 7 varies with the width of the cavity within the housing 1 and the diameter of the lead 2. The width of the trapezoidal wedges 7 should ensure that the two leads 2 are positioned after being inserted into the housing 1.

[0037] The shell 1 of the thermal link is composed of five surfaces including four surfaces and a bottom. The shell 1 is made of PA66 material with glass fiber or 95 ceramic containing alumina with high thermal conductivity.

[0038] The lead wire 2 in the thermal link has a diameter of 0.45-0.65 mm. The portion of the lead wire 2 extending from the housing 1 is covered with a Teflon insulation layer. The lead wire 2 is made of copper-clad steel wire or tinned copper wire. The maximum resistance per meter of the copper-clad steel wire with a diameter of 0.55 mm is 0.26 Ω. The diameter of the thermal element 3 is 0.55-0.8 mm.

[0039] The epoxy resin glue 5 in the thermal link comprises the following raw materials in parts by weight:

[0040] 45-65 parts of phenolic epoxy resin, 12-20 parts of alicyclic amine, 0.2-1 part of fumed silica, 0.3-0.6 part of defoaming agent, 5-15 parts of calcium carbonate, 5-9 parts of aluminum hydroxide, and 7-16 parts of barium sulfate.

[0041] The filler particle size or coarseness of the epoxy resin glue 5 in the thermal cutout is as follows: calcium carbonate: 2000-3000 mesh, aluminum hydroxide: 2000 mesh, barium sulfate: 2000-3000 mesh.

[0042] When assembling the thermal link, first prepare epoxy resin glue 5 according to the above recipe. Then weld the thermal element 3 to one end of the two leads 2. Then, place the leads 2 with the thermal element 3 welded thereto into the housing 1 with a trapezoidal wedge 7. The upper portion of the trapezoidal wedge 7 has a guide surface. The thickness of the trapezoidal wedge 7 varies with the width of the cavity in the housing 1 and the diameter of the leads 2. The width of the trapezoidal wedge 7 should ensure that the two leads 2 are positioned after being inserted into the housing 1. The two trapezoidal wedges 7 secure the thermal element 3 welded between the two leads 2 to one side of the identification surface 8 on the bottom of the housing 1, ensuring that the thermal element 3 can contact the inner wall of the mounting surface 6 at the bottom of the housing 1. Using a glue dispenser with a heating device, melted flux 4 is dispensed around the thermal element 3. The other end of the lead 2 extends out of the housing 1. Finally, the opening of the housing 1 is sealed with the prepared epoxy resin glue 5.

[0043] When an abnormality in the LED lamp circuit causes the surface temperature of the rectifier diode in the circuit to rise rapidly, the temperature of the thermal-link's mounting surface 6, which is in direct contact with the outer surface of the diode, also rises. The heat energy absorbed by the thermal-link's mounting surface 6 is directly transferred to the thermal element 3 and lead 2. When the temperature of the thermal element 3 rises to the rated operating temperature, the thermal element 3 will quickly fuse with the help of the melted flux 4, achieving the purpose of protecting the circuit.

[0044] All features disclosed in this specification, or all combinations and relative positions of components disclosed, may be combined in any manner, except for mutually exclusive features and / or steps. Any feature disclosed in this specification (including claims and abstract), unless otherwise stated, may be replaced by an equivalent or similar alternative feature. That is, unless otherwise stated, each feature is merely an example of a set of equivalent or similar features.

[0045] The above description is only a non-limiting embodiment of the present invention, and a large number of embodiments can be derived therefrom. For ordinary technicians in this field, without departing from the creative concept of the present invention and without making creative work, several modified and improved embodiments can be made, which all fall within the scope of protection of the present invention.

Claims

1. An alloy type thermal fuse for fast-blow LED lamps, comprising a housing (1), a lead (2), a thermal element (3), a flux (4), an epoxy resin adhesive (5), a mounting surface (6), a trapezoidal wedge (7), and an identification surface (8), characterized in that: In the thermal fuse, trapezoidal wedges (7) are respectively provided on both sides of the inner wall of the identification surface (8) of the shell (1), and two leads (2) are respectively inserted between the two trapezoidal wedges (7) and the inner wall of the mounting surface (6) of the shell (1). One end of the two leads (2) is welded by the thermal element (3) and then overlapped. The thermal element (3) is filled with flux (4) around. One side of the thermal element (3) is in direct contact with the inner wall of the mounting surface (6) of the shell (1). The other end of the lead (2) is welded by the thermal element (3). Extending out of the housing (1), the opening of the housing (1) is sealed with epoxy resin glue (5); two trapezoidal wedges (7) in the housing (1) of the thermal fuse are located on one side of the inner identification surface (8) of the housing (1), and a guide surface is provided on the upper part of the trapezoidal wedge (7). The thickness of the trapezoidal wedge (7) varies with the width of the space in the housing (1) and the diameter of the lead (2). The width of the trapezoidal wedge (7) should be able to ensure that the two leads (2) are positioned after being inserted into the housing (1).

2. The alloy thermal cutoff for fast-blow LED lamps according to claim 1, characterized in that: The shell (1) of the thermal fuse is composed of five surfaces including four surfaces and a bottom. The shell (1) is made of PA66 material plus glass fiber or 95 ceramic containing alumina with high thermal conductivity.

3. The alloy thermal cutoff for fast-blow LED lamps according to claim 1, characterized in that: The lead wire (2) in the thermal fuse has a diameter of 0.45-0.65 mm, and the portion of the lead wire (2) extending out of the housing (1) is covered with a Teflon insulation layer. The lead wire (2) is made of copper-clad steel wire or tinned copper wire, and the maximum resistance per meter of the copper-clad steel wire with a diameter of 0.55 mm is 0.26 Ω. The diameter of the thermal element (3) is 0.55-0.8 mm.

4. The alloy thermal cutoff for fast-blow LED lamps according to claim 1, characterized in that: The epoxy resin glue (5) in the thermal fuse comprises the following raw materials in parts by weight: 45-65 parts of phenolic epoxy resin, 12-20 parts of alicyclic amine, 0.2-1 part of fumed silica, 0.3-0.6 part of defoaming agent, 5-15 parts of calcium carbonate, 5-9 parts of aluminum hydroxide, and 7-16 parts of barium sulfate.

5. The alloy thermal cutoff for fast-blow LED lamps according to claim 1, characterized in that: The filler particle size or coarseness of the epoxy resin glue (5) in the thermal fuse is as follows: calcium carbonate: 2000-3000 mesh, aluminum hydroxide: 2000 mesh, barium sulfate: 2000-3000 mesh.

Images