Fusible body structure
By setting an alternating thin and thick structure on the fusible element of the fuse, the fuse is preferentially melted at the narrow neck, which solves the problem of aging and instantaneous melting of the fuse under the impact of surge current, and improves the protection performance and life of the fuse.
Patent Information
- Application Number
- CN202422993413.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-05
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2034-12-05
AI Technical Summary
Existing fuses are prone to aging or instantaneous melting when faced with surge current impacts, and their I2T value is insufficient, resulting in poor protection performance.
Design a fusible body structure by setting thin and thick segments spaced apart on the fusible body. The thick segment has a narrow neck. When melting, the narrow neck is the preferred point. The cross-sectional area of the thick segment is larger than that of the thin segment. The materials of the thick segment and the thin segment can be the same or different. The thick segment has through holes to enhance the current carrying capacity.
It improves the stability and protection performance of the fuse when facing surge current impact, enhances its ability to withstand pulse current, and extends the service life of the fuse.
Smart Images
Figure CN223527115U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to the technical field of circuit overcurrent protection device, and particularly relates to a fusible body structure. BACKGROUND
[0002] Fuse (fuse) refers to when the current exceeds the specified value, the heat generated by itself makes the fusible body melt, disconnects the circuit and protects the circuit. The reason for the disconnection of the fuse is generally long-time load thermal fatigue aging disconnection and surge current impact disconnection.
[0003] The I 2 t value of the fuse refers to the melting heat of the fuse, also known as the melting capacity or melting heat. It represents the maximum energy that the fuse can absorb before reaching the melting state, that is, the square of the current multiplied by time (I2xt). In actual circuit design, calculating the I 2 t value can help determine whether the fuse can withstand the energy without melting under specific current and time conditions. I 2 t value is very important for protecting the circuit from transient overcurrent, lightning and the like. For example, there will be a surge current when the motor starts or stops, and the surge current at this time is much larger than the normal rated current, which causes the pulse to generate a thermal cycle and affect the service life of the fuse. Therefore, the I 2 T value of the fuse when applied should be much larger than the I 2 T value of the pulse. The common method at present is to widen the narrow neck on the fusible body in the fuse, or thicken the fusible body by tin; but the former method can easily cause hole blockage when filling; the latter method is more troublesome to operate on a single fusible body, and the consistency is not controlled, and because the total metal content increases (the overall thickness of the fusible body increases after adding tin, the entire fusible body becomes thick), the breaking performance of the fusible body is also poor. INVENTION CONTENTS
[0004] The utility model aims at providing a fusible body structure which can prevent the fuse from melting when it is subjected to high-multiple current instantaneous impact, can withstand pulse current impact, and improves the protection performance of the product.
[0005] To achieve the above purpose, the solution of the utility model is:
[0006] A fusible body structure is provided with thin sections and thick sections arranged at intervals on the fusible body, the thickness of the thick sections is thicker than that of the thin sections, narrow necks are arranged on each thick section, the two ends of the fusible body are thin sections, and the fusible body melts at the narrow necks first when it melts; in the direction perpendicular to the current passing direction, the minimum cross-sectional area of the narrow necks in the thick sections is smaller than that of the thin sections, and the cross-sectional area of the non-narrow necks in the thick sections is larger than that of the thin sections.
[0007] Further, the width of the thick section is equal to the width of the thin section.
[0008] Further, the length of each thick section is equal to the length of each thin section, except for the thin sections at the ends of the fusible body.
[0009] Further, the material of the thick sections and the thin sections of the fusible body is the same.
[0010] Further, the material of the thick sections and the thin sections of the fusible body is different.
[0011] Further, a narrow neck is formed in the thick section of the fusible body by providing at least one through hole, and the current passes through the length direction of the thick section, and the through holes are arranged in parallel in the width direction of the thick section when there are more than one.
[0012] Further, the fusible body is in the form of a strip, and a plurality of thick sections are provided in the fusible body.
[0013] After the above scheme is adopted, under the premise that the narrow neck is melted first, the thick section is provided, and the narrow neck is arranged on the thick section, so that the narrow neck has a larger cross-sectional area for the current to pass through, so that even in a circuit with a smaller rated current, a larger I 2 T value can be obtained when a high-multiple current instantaneous impact is received, avoiding the aging or instantaneous melting of the fuse caused by the impact of a larger pulse current, so that the performance of the product can be improved. BRIEF DESCRIPTION OF DRAWINGS
[0014] Figure 1 is a schematic view of a fusible body (one);
[0015] Figure 2 is a schematic view of a fusible body (two);
[0016] Figure 3 is a schematic view of a fusible body (three);
[0017] Figure 4 is a perspective view of a fusible body of the utility model;
[0018] Figure 5 is a sectional view of the utility model fusible body erected in the fuse;
[0019] Figure 6 is a sectional view of the utility model fusible body erected in the fuse from another angle.
[0020] BRIEF DESCRIPTION OF DRAWINGS
[0021] 1 fusible body; 11 thick section; 111 narrow neck; 12 thin section; 2 pipe body; 3 solder; 4 end cap; 10 fuse. DETAILED DESCRIPTION
[0022] In order to further explain the technical scheme of the utility model, the utility model will be described in detail below through specific embodiments.
[0023] Firstly, refer to Figure 1 , Figure 2 , Figure 3 , the working principle of the utility model is explained by a simple schematic diagram of a fusible body 1.
[0024] The working principle of the fuse 10 is based on the heat effect of current. The fusible body 1 in the fuse 10 converts the absorbed electric energy into heat energy, so heat Q is generated when the current passes through. According to the Joule-Lenz law, the heat generated when the current passes through the fusible body 1 is proportional to the square of the current intensity, the resistance of the fusible body 1 itself, and the time of current passing, and its mathematical expression is: Q=0.24I 2 RT. When a larger current appears in the circuit, the generated heat is much larger than the heat dissipated, the temperature of the fusible body 1 rises to or exceeds the melting point of its own material, and the fusible body 1 is disconnected.
[0025] When other conditions of the fuse 10 are consistent, the size and time of the current passing through are also the same, the speed of the fusible body 1 in the fuse 10 melting is only determined by the resistance R of the fusible body 1 itself. The calculation formula of the resistance R is known: R=ρL / S, so the resistivity ρ of the fusible body 1 is controlled, and when the length L is the same, the resistance R is determined by the cross-sectional area S. In Figures 1 to 3 , the cross-sectional area S of the fusible body 1 is W (width) * H (thickness). When the fusible body 1 normally melts, the main factor of its own is impedance (mainly resistance R), and the melting characteristics of the fusible body 1 with the same impedance (mainly resistance R) can be similar. According to the above conclusion, Figure 1 is a schematic diagram of a fusible body 1 with alternating thickness, Figure 2 is a schematic diagram of an existing fusible body 1 with consistent thickness, although the shapes of the fusible bodies 1 in the two diagrams are different, the resistance R of the two fusible bodies 1 can be controlled to be close to obtain similar melting characteristics.
[0026] Take a thick section 11 and a thin section 12 in Figure 1 as an example, define the lengths of the thick section 11 and the thin section 12 as L1 and L2, respectively, and also take a section with a length of L1+L2 in Figure 2 , and define the cross-sectional areas of the L1 and L2 sections in the two diagrams as S1 and S2, respectively. Assuming Figure 1 , Figure 2 that the materials of the fusible bodies 1 are the same, i.e. ρ is equal, the resistance of the two selected sections can be calculated as R=ρL1 / S1+ρL2 / S2. In this formula, the resistance R on the L1+L2 section in the two diagrams can be equal by adjusting the numerical values of L1, L2, S1, and S2, and the following is an example:
[0027] Let L1=L2=L, Figure 1 The width of the medium fusible material 1 is W=10mm, the thickness of the thick section 11L1 is H=0.12mm, and the thickness of the thin section 12L2 is H=0.08mm; Figure 2 The width of the fusible medium 1 is W=10mm and the thickness is H=0.1mm.
[0028] Calculated Figure 1 Resistance of the selected segment:
[0029] R1=ρL1 / S1+ρL2 / S2=ρL / 1.2+ρL / 0.8≈2.08ρL;
[0030] Calculated Figure 2 Resistance of the selected segment:
[0031] R2=ρL1 / S1+ρL2 / S2=ρL / 1+ρL / 1=2ρL.
[0032] Note that the same value for ρ is used in the above examples only for ease of calculation. Figure 1 , Figure 2 The materials (i.e., the value of ρ) on the L1 and L2 segments of the fusible medium do not have to be the same, and R1≈R2 can also be achieved by adjusting various parameters.
[0033] Since R1≈R2, the two selected fusible elements 1 and the fuse 10 containing the fusible elements 1 have approximately the same fusing characteristics under normal fusing conditions. When the fuse 10 is subjected to a large instantaneous pulse current (such as the surge current that exists when a motor starts or stops), there is a risk that insufficient heat dissipation may lead to instantaneous fusing or rapid aging. In this case, the fuse 10's ability to withstand pulse current is different from the fuse 10's own I... 2 The T-value is related to the I-value that fuse 10 can withstand. 2 The T value is related to the cross-sectional area of the fusible material 1 through which the current passes. When controlling... Figure 1 , Figure 2 When the fuse 10 blows at the narrow neck 111, because Figure 1 The narrow neck 111 is disposed on the thick section 11, and its thickness is greater than Figure 2 The thickness of the narrow neck 111, assuming the width of the narrow neck 111 portion is the same, Figure 1 The cross-sectional area at the narrow neck 111 is relatively large Figure 2 The cross-sectional area at the narrow neck 111 is large, correspondingly containing Figure 1 The fuse 10 of the fusible element 1 in the middle 2The T value is also large, so compared with the thin and thick consistent fusible body 1 with similar fusing characteristics, the thin and thick alternating fusible body 1 with the narrow neck 111 arranged on the thick section 11 can make the fuse 10 bear larger pulse current impact and be more stable in performance.
[0034] According to the above principle, referring to Figure 2 In an embodiment of the utility model, the thin section 12 and the thick section 11 are arranged at intervals on the fusible body 1, the thickness of the thick section 11 is thicker than that of the thin section 12, the narrow neck 111 is arranged on each thick section 11, the two ends of the fusible body 1 are the thin sections 12, and the fusible body 1 is fused from the narrow neck 111 first. The fusible body 1 in the embodiment is in the form of a strip, and two thick sections 11 are arranged at intervals in the fusible body 1. The thick section 11 can also be arranged in multiple numbers according to the length of the width.
[0035] In the above structure, the thin section 12 and the thick section 11 are arranged at intervals in the fusible body 1, and the structure can be formed by processes such as calendering or fusion welding.
[0036] To ensure that the fusible body 1 is fused from the narrow neck 111 first, in the embodiment, the minimum cross-sectional area of the narrow neck 111 in the thick section 11 is smaller than the cross-sectional area of the thin section 12 in the direction perpendicular to the current passing direction, so that the fusible body 1 can be fused at the narrow neck 111 first, and the cross-sectional area of the thick section 11 at the position other than the narrow neck 111 is larger than the cross-sectional area of the thin section 12. The size relationship of the cross-sectional areas can be realized by respectively controlling the thickness and width of the thin section 12, the thickness of the thick section 11, the width of the narrow neck 111 of the thick section 11 and the width of the position other than the narrow neck 111 of the thick section 11. In the embodiment, the width of the thick section 11 is equal to the width of the thin section 12, and the thicknesses of the thin section 12 and the thick section 11 are different.
[0037] Further, the length of each thick section 11 and the length of each thin section 12 can be the same or different, for example, the length of the thick section 11 is shorter. In the embodiment, at least one through hole is arranged in the thick section 11 of the fusible body to form the narrow neck 111 with a width smaller than the width of the fusible body 1, so as to improve the breaking capacity. The current passes through the thick section 11 in the length direction, and when there are more than one through hole, the through holes are arranged in parallel in the width direction of the thick section 11, and the multiple interval through holes form the narrow neck on the thick section 11. Of course, the narrow neck can also be formed by inwardly recessing notches in the fusible body.
[0038] The materials of the thick section 11 and the thin section 12 of the fusible body 1 can be the same or different, that is, the resistivity p of the thick section 11 and the thin section 12 also does not need to be the same.
[0039] Referring to Figure 1 , Figure 4 Figure 5 Figure 6When the fusible body 1 of the embodiment is arranged in the tube body 2 of the fuse 10, the thin sections 12 at both ends of the fuse 10 are welded on the soldering tin 3 inside the end caps 4 at both ends of the tube body 2, and the thick sections 11 and the narrow necks 111 on the thick sections 11 arranged at intervals in the middle ensure that the fuse 10 has a larger I 2 T value, that is, has stronger anti-impulse current impact capability.
[0040] The above is only one embodiment of the utility model, and does not limit the utility model, and any modification, equivalent replacement and improvement within the spirit and principle of the utility model should be included in the protection scope of the utility model.
Claims
1. A meltable structure, characterized by: The fusible body is provided with thin sections and thick sections arranged at intervals, the thickness of the thick sections is greater than that of the thin sections, each thick section is provided with a narrow neck, the two ends of the fusible body are thin sections, and the fusible body is first melted at the narrow neck when it is melted.
2. A meltable structure according to claim 1, wherein: The width of the thick section is equal to the width of the thin section.
3. A meltable structure according to claim 1, wherein: The length of each thick section is equal to the length of each thin section except the thin sections at the two ends of the fusible body.
4. A meltable structure according to claim 1, wherein: The material of the thick sections and the thin sections of the fusible body is the same.
5. A meltable structure according to claim 1, wherein: The material of the thick sections and the thin sections of the fusible body is different.
6. A meltable structure according to claim 1, wherein: The narrow neck is formed by at least one through hole in the thick section of the fusible body, the current passes through the length direction of the thick section, and the through holes are arranged in parallel in the width direction of the thick section when there are more than one through hole.
7. A meltable structure according to any one of claims 2 to 6, wherein: The fusible body is in the form of a strip, and the fusible body is provided with a plurality of thick sections.