fuse

Abstract

To provide a fuse in which a fusing part of a fuse element can be visually recognized from the outside and a housing is hardly damaged when the fusing part of the fuse element is fused.SOLUTION: A fuse 900 includes a fuse element 100 and a housing 500 that houses a fuse portion 120 of the fuse element 100, wherein the housing 500 is provided with a viewing window 240 at a position facing the fuse portion 120, a cover member 600 that overlaps the viewing window 240 is attached to the housing 500, and a ventilation space X1 is formed between the cover member 600 and the housing 500.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention mainly relates to fuses used in automotive electrical circuits and the like.

Background Art

[0002] Conventionally, fuses have been used to protect electrical circuits mounted in automobiles and the like, as well as various electrical components connected to the electrical circuits. Specifically, when an unintended overcurrent flows in the electrical circuit, the fuse section melts due to heat generated by the overcurrent, protecting the various electrical components from excessive current flow.

[0003] There are various types of fuses depending on the application. For example, the fuse of Patent Document 1 includes a fuse element and a housing that houses the fuse section of the fuse element. In addition, in order for the user to visually check from the outside whether the fuse section of the fuse element has melted, it has been required to provide a structure in the housing such that the fuse section can be seen. Furthermore, since a strong internal pressure is applied to the housing by the gas generated when the fuse section of the fuse element melts, it is also required that the housing does not break.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0005] Therefore, in view of the above problems, the present invention provides a fuse in which the fuse section of the fuse element can be visually recognized from the outside and the housing is less likely to break when the fuse section of the fuse element melts.

Means for Solving the Problems

[0006] The fuse of the present invention comprises a fuse element and a housing that houses the molten portion of the fuse element, wherein the housing is provided with a viewing window at a position opposite to the molten portion, a cover member is attached to the housing that overlaps the viewing window, and a ventilation space is formed between the cover member and the housing.

[0007] According to the above features, when the fuse element melts inside the housing, the gas generated is released to the outside through the ventilation space and the viewing window. Therefore, it is possible to prevent the housing from being damaged due to an increase in internal pressure caused by the gas. In addition, the melted part of the fuse element can be visually inspected through the cover member that overlaps with the viewing window.

[0008] The fuse of the present invention is characterized in that the cover member is located inside the housing.

[0009] According to the above features, even if the cut section is subjected to outward pressure from the gas generated during the cutting process, the cover member will not detach from the housing.

[0010] The fuse of the present invention is characterized in that a ventilation space is formed between the cover member and the housing by a projection.

[0011] According to the above features, the gas generated when the fuse element's fused portion ruptures is released to the outside through the ventilation space and the viewing window.

[0012] The fuse of the present invention is characterized in that a ventilation space is formed between the cover member and the housing by a groove.

[0013] According to the above features, the gas generated when the fuse element's fused portion ruptures is released to the outside through the ventilation space and the viewing window. [Effects of the Invention]

[0014] As described above, with the fuse of the present invention, the fused portion of the fuse element can be seen from the outside, and the housing is less likely to be damaged when the fused portion of the fuse element fused. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1(a) is an overall perspective view of the fuse element 100, and Figure 1(b) is a plan view of the fuse element 100. [Figure 2] Figure 2(a) is an external perspective view of the housing segment 200, and Figure 2(b) is an external plan view of the housing segment 200. [Figure 3] Figure 3(a) is an inside perspective view of the housing segment 200, and Figure 3(b) is an inside plan view of the housing segment 200. [Figure 4] Figure 4(a) is an inside perspective view of the housing segment 300, and Figure 4(b) is an inside plan view of the housing segment 300. [Figure 5] Figure 5(a) is a side view of the housing segment 300, Figure 5(b) is a cross-sectional view along A-A, and Figure 5(c) is a cross-sectional view along B-B. [Figure 6] Figure 6(a) is a perspective view of the cover member 600, and Figure 6(b) is a plan view of the cover member 600. [Figure 7] Figure 7(a) is a perspective view showing the cover member 600 attached to the housing segment 300, and Figure 7(b) is a perspective view showing the fuse element 100 attached to the housing segment 300, with the cover member 600 and housing segment 200 attached. [Figure 8] Figure 8(a) is a perspective view of the assembled fuse 900, Figure 8(b) is a plan view of the fuse 900, and Figure 8(c) is a front view of the fuse 900. [Figure 9] Figure 9(a) is a cross-sectional view taken along line C-C in Figure 8(b), Figure 9(b) is an enlarged cross-sectional view of the area around the viewing window 240 in Figure 9(a), and Figure 9(c) is a cross-sectional view taken along line D-D in Figure 8(b).

Explanation of Symbols

[0016] 100 fuse element 120 fusing part 130 mounting hole 400 mounting projection 240 viewing window 500 housing 600 cover member 610 main body part 613 projection part 620 leg part 900 fuse X1 ventilation space

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the shapes, materials, etc. of each member of the fuse in the embodiments described below are shown as examples and are not limited thereto.

[0018] FIG. 1 shows the fuse element 100 of the fuse 900 according to the present invention. Note that FIG. 1(a) is an overall perspective view of the fuse element 100, and FIG. 1(b) is a plan view of the fuse element 100.

[0019] As shown in Figure 1, the fuse element 100 includes a terminal portion 110 that can conduct electricity to an external electrical circuit, and a fusible portion 120 located between the terminal portions 110 on both sides. The fuse element 100 is integrally formed by punching out a flat plate material of uniform thickness made of a conductive metal such as copper or its alloy into the shape shown in Figure 1 using a press or the like. The fusible portion 120 is formed by bending a linear body 121 that is narrower and longer than the fuse element 100 into a Z shape, and is provided with a welded portion 122 to which a low melting point metal such as tin, silver, lead, nickel, or an alloy thereof is welded. The fusible portion 120 heats up and melts when an unintended overcurrent flows through the electrical circuit, etc., as the narrowed linear body 121 passes through, thereby interrupting the overcurrent. Furthermore, when an overcurrent flows, the molten welded portion 122 combines with the linear body 121, lowering the melting point of the linear body 121, and causing the linear body 121 to melt and cut more quickly and effectively. The melting portion 120 is designed to heat up and melt to interrupt an overcurrent when an unintended overcurrent flows through an electrical circuit, etc., when the narrowed linear body 121 is subjected to such an overcurrent. However, it is not limited to this, and any configuration can be adopted as long as it can heat up and melt to interrupt an overcurrent when an unintended overcurrent flows through an electrical circuit, etc., such as providing a small hole in a part of the melting portion 120 to melt the narrowed portion.

[0020] The terminal portion 110 is provided with a connection hole 111 for connecting to an electrical circuit or the like. The terminal portion 110 is also provided with a mounting hole 130 for inserting and fixing the mounting projection of the housing 500, which will be described later. The mounting hole 130 has a roughly elliptical elongated shape, and the length L1 of the mounting hole 130 is greater than the width W1 (length L1 > width W1). The mounting hole 130 extends in the longitudinal direction P1 (i.e., the direction along the length L1). Furthermore, the longitudinal direction P1 of the mounting hole 130 coincides with the longitudinal direction P2 of the fuse element 100 (the axis direction of the straight line connecting the terminal portions 110 on both sides). In other words, the mounting hole 130 extends in the longitudinal direction P2 of the fuse element 100. Therefore, the mounting hole 130 is less likely to obstruct the flow of current along the longitudinal direction of the fuse element 100 and is less likely to affect the electrical characteristics of the fuse element 100.

[0021] Furthermore, although the mounting hole 130 extends in the longitudinal direction P2 of the fuse element 100, it is not limited to this, and the mounting hole 130 can extend in a direction perpendicular to the longitudinal direction P2 of the fuse element 100, or in any direction intersecting the longitudinal direction P2 of the fuse element 100. Also, although the mounting hole 130 has a substantially elliptical elongated hole shape, it is not limited to this, and the mounting hole 130 may have any shape, such as a substantially rectangular shape, as long as the length L1 of the mounting hole 130 is greater than the width W1. In addition, a claw 112 that protrudes toward the fusible portion 120 side is provided on a part of the terminal portion 110 of the fuse element 100.

[0022] Next, with reference to Figures 2 and 3, the housing division piece 200 of the housing 500 of the fuse 900 according to the present invention will be described. The housing 500 is composed of a pair of housing division pieces 200 and a housing division piece 300. Figure 2(a) is an external perspective view of the housing division piece 200, Figure 2(b) is an external plan view of the housing division piece 200, Figure 3(a) is an internal perspective view of the housing division piece 200, and Figure 3(b) is an internal plan view of the housing division piece 200.

[0023] As shown in Figures 2 and 3, the housing segment 200 is made of synthetic resin and has a roughly rectangular shape. It includes a housing section 210 for housing the fusible portion 120 of the fuse element 100, and a fixing section 220 for clamping and fixing a part of the terminal portion 110 of the fuse element 100. The outer wall 230 surrounding the outside of the housing section 210 is provided with a viewing window 240 in the form of a vertically penetrating hole. This viewing window 240 is positioned opposite the fusible portion 120 of the fuse element 100 housed in the housing section 210, allowing the fusible portion 120 to be viewed from the outside. Additionally, a projection 231 protruding inward is provided on the inner side (housing section 210 side) of the outer wall 230. This projection 231 is a point through which the cover member described later is inserted.

[0024] Furthermore, a recess 251 is provided on the inner surface of the side wall 250 surrounding the side of the housing section 210, recessing outwards. This recess 251 is where the legs of the cover member, which will be described later, are positioned, and it extends linearly from the end 252 of the side wall 250 toward the outer wall 230, along the legs.

[0025] Furthermore, the front side of the fixing portion 220 is a recess 221, and a fixing hole 260 is provided in the recess 221 that penetrates vertically. The fixing hole 260 is configured to allow the mounting projection 400 of the housing division piece 300, which will be described later, to be inserted. Specifically, the fixing hole 260 comprises a first fixing hole 261 through which the tip of the mounting projection 400 is inserted, and a second fixing hole 262 extending laterally from the first fixing hole 261. In addition, a notch 263 is provided in a part of the inner wall of the first fixing hole 261, and the notch 263 is in communication with the housing portion 210. As a result, the gas generated when the fusible portion 120 of the fuse element 100 is blown is released to the outside from the housing portion 210 through the notch 263 and through the second fixing hole 262 of the fixing hole 260. This prevents the internal pressure of the housing 500 from rising and damaging the housing 500 when the fusible portion 120 is blown. Even when the mounting projection 400 is inserted through the fixing hole 260 and fixed in place, a small gap remains that allows gas to be discharged.

[0026] Next, with reference to Figures 4 and 5, the housing segment 300 of the housing 500 of the fuse 900 according to the present invention will be described. Figure 4(a) is an inside perspective view of the housing segment 300, Figure 4(b) is an inside plan view of the housing segment 300, Figure 5(a) is a side view of the housing segment 300, Figure 5(b) is a cross-sectional view along A-A, and Figure 5(c) is a cross-sectional view along B-B.

[0027] As shown in Figure 4, the housing segment 300 has basically the same configuration as the housing segment 200. Specifically, the housing segment 300 is made of synthetic resin, has a roughly rectangular shape, and includes a housing section 310 that accommodates the fusible portion 120 of the fuse element 100, and a fixing section 320 that clamps and fixes a part of the terminal portion 110 of the fuse element 100. In addition, the outer wall 330 surrounding the outside of the housing section 310 is provided with a viewing window 340 in the form of a vertically penetrating hole. This viewing window 340 is positioned opposite the fusible portion 120 of the fuse element 100 housed in the housing section 310, allowing the fusible portion 120 to be viewed from the outside. Furthermore, the inner side of the outer wall 330 (the side of the housing section 310) is provided with a projection 331 that protrudes inward. This projection 331 is a point through which the cover member described later is inserted.

[0028] Furthermore, a recess 351 is provided on the inner surface of the side wall 350 surrounding the side of the housing section 310, recessing outwards. This recess 351 is the part where the legs of the cover member, which will be described later, are positioned, and extends linearly from the end 352 of the side wall 350 toward the outer wall 330, along the legs. In addition, the end 352 that is aligned linearly with the recess 351 is recessed toward the outer wall 330 than the two adjacent end 352s, so a recessed mounting portion 353 is formed. This mounting portion 353 is the part that clamps and secures the fixing portion of the legs of the cover member, which will be described later.

[0029] Furthermore, mounting projections 400 are provided on the inner surfaces of the fixing portions 320 on both sides of the housing segment 300, projecting inward. The mounting projection 400 comprises a base end portion 410 connected to the fixing portion 320 and a tip portion 420 projecting from the base end portion 410. The base end portion 410 of the mounting projection 400 has a substantially elliptical shape in plan view and is a corresponding shape that approximates the mounting hole 130 so that it can be inserted into the mounting hole 130 of the fuse element 100. In addition, the tip portion 420 of the mounting projection 400 is configured to be inserted into the fixing hole 260 of the housing segment 200. Moreover, the upper end 411 of the base end portion 410 is inclined, making it easier to insert into the second fixing hole 262 of the fixing hole 260 of the housing segment 200. Furthermore, the tip portion 420 of the mounting projection 400 is substantially circular in plan view and is configured to be inserted into the first fixing hole 261 of the fixing hole 260 of the housing segment 200. In addition, the upper end 421 of the tip portion 420 is inclined to facilitate insertion into the fixing hole 260 of the housing segment 200.

[0030] As shown in Figure 5, the cross-sectional area S1 of the base end 410 of the mounting projection 400 is larger than the cross-sectional area S2 of the tip end 420 of the mounting projection 400. When the fuse 900 is assembled, as will be described later, the mounting projection 400 extends perpendicular to the longitudinal direction P2 of the fuse element 100. The height axis P3 of the mounting projection 400 is perpendicular to the longitudinal direction P2 of the fuse element 100. As shown in Figure 5(b), the cross-sectional area S1 of the base end 410 of the mounting projection 400 is the cross-sectional area when the base end 410 is cut with a cross-section perpendicular to the axis P3. Also, as shown in Figure 5(c), the cross-sectional area S2 of the tip end 420 of the mounting projection 400 is the cross-sectional area when the tip end 420 is cut with a cross-section perpendicular to the axis P3.

[0031] The base end portion 410 of the mounting projection 400 has a roughly elliptical cross-section, but is not limited to this; any cross-sectional shape, such as a roughly rectangular shape, is acceptable as long as it can be inserted into the mounting hole 130 of the fuse element 100. Furthermore, the tip portion 420 of the mounting projection 400 has a roughly circular cross-section, but is not limited to this; any cross-sectional shape, such as a roughly square shape, is acceptable as long as it can be inserted into the fixing hole 260 of the housing segment 200.

[0032] Next, with reference to Figure 6, the cover member 600 of the fuse 900 according to the present invention will be described. Figure 6(a) is a perspective view of the cover member 600, and Figure 6(b) is a plan view of the cover member 600.

[0033] As shown in Figure 6, the cover member 600 is made of a transparent or translucent synthetic resin and comprises a flat main body portion 610 and leg portions 620 extending laterally and downward from both sides of the main body portion 610. The main body portion 610 is configured to overlap with the viewing window 240 of the housing segment 200 and includes a protrusion 611 positioned within the viewing window 240. The main body portion 610 is transparent or translucent so that the fused portion 120 of the fuse element 100 housed in the housing portion 210 can be viewed from the outside. Mounting holes 612 are provided at the four corners of the main body portion 610 into which the projections 231 of the housing segment 200 are inserted. The main body portion 610 is also provided with projections 613 that protrude from the surface of the main body portion 610.

[0034] The legs 620 are provided one on each side of the main body 610. The legs 620 are located in the center of the main body 610 and have a base end 621 extending laterally from the main body 610 and a tip end 622 extending downward from the base end 621. The tip end 622 is provided with a stepped fixing part 623 that protrudes laterally. Although the legs 620 are provided one on each side in the center of the main body 610, this is not limited to this arrangement. The legs 620 may be provided in any number and at any location, such as at each of the four corners of the main body 610 (a total of four legs).

[0035] Next, with reference to Figures 7 and 8, the manner in which the fuse 900 according to the present invention is assembled will be described. Figure 7(a) is a perspective view showing the cover member 600 attached to the housing segment 300, Figure 7(b) is a perspective view showing the fuse element 100 attached to the housing segment 300 and the cover member 600 and housing segment 200 attached, Figure 8(a) is a perspective view of the assembled fuse 900, Figure 8(b) is a plan view of the fuse 900, and Figure 8(c) is a front view of the fuse 900.

[0036] As shown in Figure 7(a), the cover member 600 is attached to the housing portion 310 inside the housing portion 300 so as to overlap the viewing window 340 of the housing portion 300. Specifically, with the cover member 600 inverted, the main body portion 610 of the cover member 600 is placed over the viewing window 340, and the projection 331 of the housing portion 300 is inserted into the mounting hole 612 of the main body portion 610 to attach the cover member 600 to the housing portion 300. The fixing portion 623 of the leg portion 620 of the cover member 600 is placed on the concave mounting portion 353 of the side wall 350 of the housing portion 300. In addition, since the outer surface of the leg portion 620 of the cover member 600 is housed in the recess 351 of the side wall 350 of the housing portion 300, the portion of the leg portion 620 that protrudes into the inside of the housing portion 310 can be reduced. Therefore, the legs 620 of the cover member 600 prevent narrowing the space inside the housing 310, and the space inside the housing 310 can be kept as wide as possible. This prevents the internal pressure inside the housing 500 from becoming excessively high when the fused portion 120 of the fuse element 100 bleeds, thus preventing damage to the housing 500.

[0037] Next, as shown in Figure 7(b), the fuse element 100 is mounted on top of the housing segment 300 to which the cover member 600 is attached. Specifically, the terminal portion 110 of the fuse element 100 is placed on the fixing portion 320 of the housing segment 300, and the base end portion 410 of the mounting projection 400 is inserted through the mounting hole 130 of the fuse element 100. The fused portion 120 of the fuse element 100 is located within the housing portion 310 of the housing segment 300.

[0038] Next, the cover member 600 is attached to the housing portion 210 inside the housing division piece 200. The method of attachment is the same as the method of attaching the cover member 600 to the housing division piece 300, as shown in Figure 7(a). Then, the housing division piece 200 with the cover member 600 attached is attached to the housing division piece 300 so as to sandwich the fuse element 100. Specifically, the fixing portion 220 of the housing division piece 200 is placed on the terminal portion 110 of the fuse element 100, and the fixing portion 220 of the housing division piece 200 and the fixing portion 320 of the housing division piece 300 sandwich the terminal portion 110 of the fuse element 100 from above and below. Then, the tip portion 420 of the mounting projection 400 is inserted through the fixing hole 260 of the housing division piece 200. As shown in Figure 8(a), the housing 500, which is composed of the housing segment 200 and the housing segment 300, is connected to the fuse element 100 with the fuse element 100's fused portion 120 housed inside.

[0039] As shown in Figure 8(a), the tip portion 420 of the mounting projection 400 protrudes from the fixing hole 260 of the housing segment 200, so the tip portion 420 is heated and flattened. Then, the heated and flattened tip portion 420 (hereinafter referred to as the head portion 422) is welded to the fixing portion 220 around the fixing hole 260 (so-called crimping), and the housing segment 200 and the housing segment 300 are firmly fixed together. Also, since the upper end 421 of the tip portion 420 is inclined, the volume is smaller at the upper end 421 and it melts more easily. Therefore, the upper end 421 of the tip portion 420 is easier to heat and flatten, and the welding time is shorter. In addition, it is possible to prevent the flattened head portion 422 from protruding from the fixing portion 220. Note that as shown in Figure 8(b), the tips 420 of all mounting projections 400 are heated and flattened.

[0040] Furthermore, as shown in Figure 7(b), the fixing portion 623 of the cover member 600 attached to the upper housing segment 200 is positioned within the mounting portion 353 of the lower housing segment 300 and overlaps with the fixing portion 623 of the cover member 600 attached to the lower housing segment 300. Then, as shown in Figure 8(a), when the housing segment 200 and the housing segment 300 are assembled, the fixing portion 623 of the upper cover member 600 and the fixing portion 623 of the lower cover member 600 are sandwiched and fixed between the housing segment 200 and the housing segment 300 in an overlapping state. In this way, the cover member 600 is firmly fixed inside the housing 500.

[0041] Furthermore, as shown in Figure 8, in the assembled fuse 900, the terminal portions 110 of the fuse element 100 protrude laterally from both sides of the housing 500, and the fused portion 120 of the fuse element 100 is housed inside the housing 500. The fused portion 120 of the housing 500 can be seen from the outside through the main body portion 610 of the cover member 600 which is superimposed on the viewing window 340 of the housing 500.

[0042] Furthermore, when connecting the fuse 900 to an electrical circuit or the like to be protected, the fuse 900 is fixed to the electrical circuit or the like by inserting a bolt or the like through the connection hole 111 of the terminal portion 110 of the fuse element 100 and fastening it. When the fixing member such as a bolt inserted through the connection hole 111 of the fuse element 100 is rotated during fastening, a stress F1 is applied around the connection hole 111 of the terminal portion 110 in a direction intersecting the longitudinal direction P2 of the fuse element 100. As a result, the stress F1 is concentrated at the connection point between the fuse element 100 and the housing 500, that is, at the connection point between the mounting hole 130 of the terminal portion 110 and the mounting projection 400 of the housing 500, and there is a risk that the housing 500 may be damaged. Therefore, in the fuse 900 of the present invention, the mounting hole 130 is made into an elongated hole shape. As a result, compared to the case where the mounting hole 130 is a simple circular hole, the area of ​​the connection point between the mounting projection 400 and the mounting hole 130 is increased, and the strength of the connection point is increased. As a result, when fastening fasteners such as bolts to secure the fuse 900, damage to the housing 500 can be prevented.

[0043] Furthermore, the base end 410 of the mounting projection 400 is inserted into the mounting hole 130 of the fuse element 100 and directly connected to it, making it the point most susceptible to stress. For this reason, the cross-sectional area of ​​the base end 410 was increased to give it greater strength than the tip end 420. On the other hand, the tip end 420 is not directly connected to the mounting hole 130 of the fuse element 100, but is inserted into the fixing hole 260 of the housing segment 300, so its strength may be lower than that of the base end 410. In this way, the cross-sectional area of ​​the base end 410 of the mounting projection 400 is made larger than that of the tip end 420, thereby improving and optimizing the strength of the mounting projection 400.

[0044] Furthermore, the claws 112 provided on the terminal portion 110 of the fuse element 100 are located adjacent to the mounting hole 130 and are in contact with the inner surface of the housing 500. Therefore, the claws 112 reinforce the area around the mounting hole 130, preventing deformation of the area around the mounting hole 130 due to the stress F1 concentrated around the mounting hole 130.

[0045] Next, Figure 9 shows the structure inside the housing 500. Figure 9(a) is a cross-sectional view taken along line C-C in Figure 8(b), Figure 9(b) is an enlarged cross-sectional view of the area around the viewing window 240 in Figure 9(a), and Figure 9(c) is a cross-sectional view taken along line D-D in Figure 8(b).

[0046] As shown in Figures 9(a) and 9(b), the projection 613 of the cover member 600 is in point contact with the back side of the outer wall 230 of the housing 500. A ventilation space X1 is provided between the back side of the outer wall 230 of the housing 500 and the main body 610 of the cover member 600 by the projection 613. Therefore, as shown in Figure 9(b), the gas G1 generated when the fused portion 120 of the fuse element 100 is fused inside the housing 500 is released to the outside through the ventilation space X1 and the viewing window 240. This prevents the internal pressure inside the housing 500 from rising due to the gas G1 and causing damage to the housing 500. The convex portion 611 of the cover member 600 is located inside the viewing window 240 of the housing 500, but a small gap X2 is provided between the convex portion 611 and the viewing window 240, allowing the gas G1 to be released.

[0047] Furthermore, when the fused portion 120 of the fuse element 100 melts, the gasified metal components of the fused portion scatter within the housing 500 and adhere to the inner surface of the housing 500. When voltage is applied to the fuse 900 while the gasified metal components of the fused portion are continuously adhering to the inner surface of the housing 500, leakage current is likely to occur within the housing 500. As a result, the insulation performance between the terminal portions 110 deteriorates, and even after the fused portion 120 of the fuse element 100 melts, leakage current flows through the inner surface of the housing 500, maintaining conductivity between the terminal portions 110, which leads to the problem of melting damage to both the housing 500 and the terminal portions 110.

[0048] However, as shown in Figures 9(a) and 9(b), a ventilation space X1 is provided between the back side of the outer wall 230 of the housing 500 and the main body 610 of the cover member 600. As a result, the outer wall 230 of the housing 500 and the main body 610 of the cover member 600 are separated vertically to prevent continuous adhesion of the gasified metal components of the cutting section. Therefore, the ventilation space X1 prevents continuous adhesion of the gasified metal components of the cutting section on the inner surface of the housing 500, thereby preventing the generation of leakage current within the housing 500.

[0049] Furthermore, as shown in Figures 9(a) and 9(c), the legs 620 of the cover member 600 protrude inward from the inner surface of the housing 500. Therefore, the legs 620 prevent the gasified fused metal from continuously adhering to the inner surface of the housing 500. Specifically, the fusible metal G2 scattered from the fused portion 120 of the fuse element 100 adheres to the inner surface 625 of the legs 620 and the inner surface of the outer wall 330, but does not easily adhere to the side surface 626 of the legs 620. Therefore, the stepped legs 620, which have an inner surface 625 and a side surface 626, prevent the gasified fused metal from continuously adhering to the inner surface of the housing 500, thereby preventing the generation of leakage current inside the housing 500.

[0050] Furthermore, the fusible portion 120 of the fuse element 100 is located near the center 502 of the housing 500. The leg portion 620 is positioned on the center 502 side between the ends 501 of the housing 500. Therefore, the leg portion 620 can receive the fusible metal G2 scattered from the fusible portion 120 at the closest position above and below the fusible portion 120. As a result, the fusible metal G2 scattered radially from the fusible portion 120 is less likely to adhere to the side surface 626 of the leg portion 620 of the cover member 600. Consequently, the continuous adhesion of gasified fusible metal on the inner surface of the housing 500 is prevented, and leakage current is prevented from occurring inside the housing 500.

[0051] Furthermore, the legs 620 of the cover member 600 are provided in the minimum number necessary to support the cover member 600, that is, only one on each side of the main body 610. Therefore, the legs 620 prevent the space inside the housing 500 from becoming unnecessarily narrow, and the space inside the housing 500 can be maintained as wide as possible. This prevents the internal pressure inside the housing 500 from becoming excessively high when the fused portion 120 of the fuse element 100 blows, and thus prevents damage to the housing 500.

[0052] Furthermore, the legs 620 of the cover member 600 are continuously provided around the entire circumference of the inner surface of the housing 500 via the main body 610. The main body 610 protrudes inward from the inner surface of the housing 500, preventing the gasified metal components of the cutting section from continuously adhering to the inner surface of the housing 500. As a result, the continuous adhesion of the gasified metal components of the cutting section around the entire circumference of the inner surface of the housing 500 is reliably prevented, thereby preventing the generation of leakage current within the housing 500.

[0053] Furthermore, the cover member 600 is subjected to outward pressure by the gas G1 generated when the cutting section 120 is cut. However, since the cover member 600 is located inside the housing 500, it is difficult for the cover member 600 to detach from the housing 500 even when subjected to pressure. Although the cover member 600 is located inside the housing 500, it may also be mounted on the outside of the housing 500 if the cover member 600 is configured to be difficult for it to detach from the housing 500.

[0054] In addition, a ventilation space X1 is provided between the back side of the outer wall 230 of the housing 500 and the main body 610 of the cover member 600 by a projection 613, but this is not limited to this. If the projection 613 is not provided, the back side of the outer wall 230 of the housing 500 and the main body 610 of the cover member 600 will be in contact, but in order to form the ventilation space X1, a groove 614 is provided in the main body 610 of the cover member 600 instead of the projection 613. The groove 614 is recessed from the surface of the main body 610, one end 615 of the groove 614 communicates with the inside of the housing 500, and the other end 616 of the groove 614 communicates with the viewing window 240. Therefore, the groove 614 forms a ventilation space X1 that connects the inside and outside of the housing 500. Then, within the housing 500, the gas G1 generated when the fused portion 120 of the fuse element 100 is fused passes from one end 615 to the other end 616 of the groove 614 that forms the ventilation space X1, and is released to the outside through the viewing window 240.

[0055] Furthermore, if the projection 613 is not provided, the back surface of the outer wall 230 of the housing 500 and the main body 610 of the cover member 600 will be in contact. However, in order to form a ventilation space X1, a groove 617 may be provided on the back surface of the outer wall 230 of the housing 500 instead of the projection 613. The groove 617 is recessed from the back surface of the outer wall 230 of the housing 500, with one end 618 communicating with the inside of the housing 500 and the other end 619 communicating with the viewing window 240. Therefore, the groove 617 forms a ventilation space X1 that connects the inside and outside of the housing 500. Then, the gas G1 generated when the fused portion 120 of the fuse element 100 is fused inside the housing 500 passes from one end 618 to the other end 619 of the groove 617 that forms the ventilation space X1, and is released to the outside through the viewing window 240.

[0056] Furthermore, the fuse of the present invention is not limited to the above-described embodiments, and various modifications and combinations are possible within the scope of the claims and embodiments, and these modifications and combinations are also included within the scope of the patent rights.

Claims

1. A fuse comprising a fuse element and a housing that accommodates the fused portion of the fuse element, The housing is provided with a viewing window at a position opposite to the cutting portion. A cover member that overlaps with the viewing window is attached to the housing. A ventilation space is formed between the cover member and the housing. The fuse is characterized in that the cover member is located inside the housing.

2. The fuse according to claim 1, characterized in that a ventilation space is formed between the cover member and the housing by a projection.

3. The fuse according to claim 1, characterized in that a ventilation space is formed between the cover member and the housing by a groove.

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