Fuse

Abstract

The present invention provides a fuse that makes it possible to view a fusible part of a fuse element from the outside, and also prevents leakage current from occurring after the fusible part of the fuse element has blown.　A fuse 900 is provided with a fuse element 100 and a housing 500 in which a fusible part 120 of the fuse element 100 is accommodated, and is characterized in that: a viewing window 240 is provided to the housing 500 at a location corresponding to the fusible part 120; a cover member 600 overlapping the viewing window 240 is arranged inside the housing 500; the cover member 600 is provided with a body 610 that overlaps the viewing window 240 and a leg 620 connected to the body 610; and the leg 620 protrudes inward from the inner surface of the housing 500.

Description

fuse

[0001] The present invention relates to a fuse that is used primarily in automotive electrical circuits.

[0002] Fuses have traditionally been used to protect electrical circuits in automobiles and other vehicles, as well as various electrical components connected to the electrical circuits. Specifically, when an unintended overcurrent flows through an electrical circuit, the fuse generates heat due to the overcurrent and melts, protecting the electrical components from excessive current.

[0003] There are various types of fuses depending on their intended use. For example, the fuse disclosed in Patent Document 1 includes a fuse element and a housing that accommodates the fusing portion of the fuse element. Furthermore, there is a need for a structure on the housing that allows the user to visually check from the outside whether the fusing portion of the fuse element has blown. Furthermore, when the fusing portion of the fuse element blows, the gasified metal constituting the fusing portion scatters within the housing and adheres to the inner surface of the housing. If a voltage is applied to the fuse while the gasified metal constituting the fusing portion is continuously adhering to the inner surface of the housing, there is a risk of a leakage current occurring within the housing.

[0004] JP 2017-10823 A

[0005] In view of the above problems, the present invention provides a fuse in which the fusion portion of the fuse element can be visually confirmed from the outside and which prevents leakage current from occurring after the fusion portion of the fuse element has fused.

[0006] The fuse of the present invention comprises a fuse element and a housing that accommodates the melting portion of the fuse element, wherein the housing has a viewing window at a position opposite the melting portion, and a cover member that overlaps the viewing window is disposed inside the housing, the cover member having a main body that overlaps the viewing window and legs connected to the main body, and the legs protruding inward from the inner surface of the housing.

[0007] According to the above feature, the legs of the cover member protrude inward from the inner surface of the housing, preventing continuous adhesion of the gasified metal constituting the fusing portion to the inner surface of the housing and preventing the generation of leak current. In addition, the fusing portion of the fuse element can be visually observed through the cover member overlapping the viewing window.

[0008] The fuse of the present invention is characterized in that the legs are provided on both sides of the body.

[0009] According to the above feature, when the fusing portion of the fuse element melts, the internal pressure inside the housing is prevented from becoming excessively high, and damage to the housing can be avoided.

[0010] The fuse of the present invention is characterized in that the legs are arranged on the central side of the housing.

[0011] According to the above feature, the legs can receive the fusible metal scattered from the fusing portion at the positions closest to the fusing portion above and below the fusing portion, thereby preventing the gasified fusing portion metal from adhering continuously to the inner surface of the housing and effectively preventing the occurrence of leakage current within the housing.

[0012] As described above, the fuse of the present invention allows the fusion portion of the fuse element to be visually observed from the outside, and prevents leakage current from occurring after the fusion portion of the fuse element has fused.

[0013] 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. FIG. 2(a) is a perspective view of the outside of a housing segment 200, and FIG. 2(b) is a plan view of the outside of the housing segment 200. FIG. 3(a) is a perspective view of the inside of the housing segment 200, and FIG. 3(b) is a plan view of the inside of the housing segment 200. FIG. 4(a) is a perspective view of the inside of a housing segment 300, and FIG. 4(b) is a plan view of the inside of the housing segment 300. FIG. 5(a) is a side view of the housing segment 300, FIG. 5(b) is a cross-sectional view taken along line A-A, and FIG. 5(c) is a cross-sectional view taken along line B-B. FIG. 6(a) is a perspective view of a cover member 600, and FIG. 6(b) is a plan view of the cover member 600. Fig. 7(a) is a perspective view of the state in which the cover member 600 is attached to the housing segment 300, and Fig. 7(b) is a perspective view of the state in which the fuse element 100 is attached to the housing segment 300 and the cover member 600 and the housing segment 200 are attached. Fig. 8(a) is a perspective view of the assembled fuse 900, Fig. 8(b) is a plan view of the fuse 900, and Fig. 8(c) is a front view of the fuse 900. Fig. 9(a) is a cross-sectional view taken along the line CC in Fig. 8(b), Fig. 9(b) is an enlarged cross-sectional view of the area around the viewing window 240 in Fig. 9(a), and Fig. 9(c) is a cross-sectional view taken along the line D-D in Fig. 8(b).

[0014] REFERENCE SIGNS LIST 100 fuse element 120 fusing portion 130 mounting hole 400 mounting projection 240 viewing window 500 housing 600 cover member 610 main body 613 projection 620 leg 900 fuse X1 ventilation space

[0015] The following describes embodiments of the present invention with reference to the drawings. Note that the shapes and materials of the components of the fuse in the embodiments described below are merely examples and are not intended to limit the scope of the present invention.

[0016] 1 shows a fuse element 100 of a fuse 900 according to the present invention. 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.

[0017] As shown in FIG. 1 , fuse element 100 includes terminal portions 110 that can be electrically connected to an external electric circuit, and fusing portions 120 located between the terminal portions 110 on both sides. Fuse element 100 is integrally formed by punching a flat, uniform-thickness plate made of a conductive metal such as copper or its alloy into the shape shown in FIG. 1 using a press or the like. Fusing portion 120 is formed by bending a long, narrow, linear body 121 into a Z-shape, and is provided with a welded portion 122 made of a low-melting-point metal such as tin, silver, lead, nickel, or an alloy thereof. When an unintended overcurrent flows through an electric circuit or the like, narrowed linear body 121 generates heat, melts, and interrupts the overcurrent. Furthermore, when an overcurrent flows, the molten welded portion 122 bonds with the linear body 121, lowering the melting point of the linear body 121 and allowing the linear body 121 to melt more quickly and effectively. Note that the fusing portion 120 is configured to generate heat and melt to cut off the overcurrent when the narrowed linear body 121 causes an unintended overcurrent to flow in an electric circuit or the like, but is not limited to this, and any configuration can be adopted, such as providing a small hole in part of the fusing portion 120 to melt the narrowed portion, as long as it can generate heat, melt, and cut off the overcurrent when an unintended overcurrent flows in an electric circuit or the like.

[0018] The terminal portion 110 is provided with a connection hole 111 for connection to an electric circuit or the like. The terminal portion 110 also has a mounting hole 130 for inserting and fixing a mounting protrusion of the housing 500 (described later). The mounting hole 130 has a generally 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 so as to be elongated in a longitudinal direction P1 (i.e., the direction along the length L1). The longitudinal direction P1 of the mounting hole 130 also coincides with the longitudinal direction P2 of the fuse element 100 (the axial direction of the 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 unlikely to obstruct the flow of current along the longitudinal direction of the fuse element 100 and is unlikely to affect the electrical characteristics of the fuse element 100.

[0019] Furthermore, although the mounting hole 130 extends in the longitudinal direction P2 of the fuse element 100, this is not a limitation, and the mounting hole 130 can extend in a direction perpendicular to the longitudinal direction P2 of the fuse element 100, or the mounting hole 130 can extend in any direction intersecting the longitudinal direction P2 of the fuse element 100. Furthermore, although the mounting hole 130 has a generally elliptical elongated hole shape, this is not a limitation, and the mounting hole 130 can have any shape, such as a generally rectangular shape, as long as the length L1 of the mounting hole 130 is greater than the width W1. Furthermore, a claw 112 protruding toward the fusing portion 120 is provided on a portion of the terminal portion 110 of the fuse element 100.

[0020] Next, the housing segment 200 of the housing 500 of the fuse 900 according to the present invention will be described with reference to Figures 2 and 3. The housing 500 is composed of a pair of housing segments 200 and 300. Figure 2(a) is a perspective view of the outside of the housing segment 200, Figure 2(b) is a plan view of the outside of the housing segment 200, Figure 3(a) is a perspective view of the inside of the housing segment 200, and Figure 3(b) is a plan view of the inside of the housing segment 200.

[0021] As shown in Figures 2 and 3, the housing segment 200 is made of synthetic resin and has a generally rectangular shape. It includes an accommodation portion 210 that accommodates the fusing portion 120 of the fuse element 100 and a fixing portion 220 that clamps and fixes a portion of the terminal portion 110 of the fuse element 100. An outer wall 230 that surrounds the outside of the accommodation portion 210 is provided with a viewing window 240 in the form of a hole that penetrates vertically. This viewing window 240 is located opposite the fusing portion 120 of the fuse element 100 accommodated in the accommodation portion 210, allowing the fusing portion 120 to be viewed from the outside. A protrusion 231 that protrudes inward is provided on the inner surface (toward the accommodation portion 210) of the outer wall 230. This protrusion 231 is inserted into a mounting hole of a cover member, which will be described later.

[0022] Furthermore, a recess 251 recessed outward is provided on the inner surface of a side wall 250 that surrounds the side surface of the storage section 210. This recess 251 is a portion where the legs of a cover member (described later) are disposed, and extends linearly from an end 252 of the side wall 250 toward the outer wall 230 so as to follow the legs.

[0023] The front side of the fixing portion 220 is formed with a recess 221, which is provided with a fixing hole 260 that penetrates vertically. The fixing hole 260 is configured to allow the insertion of a mounting protrusion 400 of the housing segment 300 (described later). Specifically, the fixing hole 260 includes a first fixing hole 261 through which the tip of the mounting protrusion 400 is inserted, and a second fixing hole 262 that extends laterally from the first fixing hole 261. Furthermore, a cutout 263 is provided in a portion of the inner wall of the first fixing hole 261, and the cutout 263 communicates with the accommodating portion 210. Therefore, gas generated when the fusing portion 120 of the fuse element 100 melts is released from the accommodating portion 210 through the cutout 263 and the second fixing hole 262 of the fixing hole 260 to the outside. This prevents the internal pressure of the housing 500 from increasing when the fusing portion 120 melts, preventing damage to the housing 500. Even when the mounting projection 400 is inserted into the fixing hole 260 and fixed, there is a small gap that allows gas to be discharged.

[0024] Next, the housing segment 300 of the housing 500 of the fuse 900 according to the present invention will be described with reference to Figures 4 and 5. Figure 4(a) is a perspective view of the inside of the housing segment 300, Figure 4(b) is a plan view of the inside 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 taken along line A-A, and Figure 5(c) is a cross-sectional view taken along line B-B.

[0025] As shown in FIG. 4 , the housing segment 300 has essentially the same configuration as the housing segment 200. Specifically, the housing segment 300 is made of synthetic resin and has a generally rectangular shape. It includes an accommodation portion 310 that accommodates the fusing portion 120 of the fuse element 100 and a fixing portion 320 that clamps and fixes a portion of the terminal portion 110 of the fuse element 100. An outer wall 330 that surrounds the outside of the accommodation portion 310 is provided with a viewing window 340 in the form of a vertically penetrating hole. This viewing window 340 is located opposite the fusing portion 120 of the fuse element 100 accommodated in the accommodation portion 310, allowing the fusing portion 120 to be viewed from the outside. Furthermore, a protrusion 331 that protrudes inward is provided on the inner surface (the accommodation portion 310 side) of the outer wall 330. This protrusion 331 is inserted into a mounting hole of a cover member, which will be described later.

[0026] Furthermore, a recess 351 recessed outward is provided on the inner surface of a side wall 350 surrounding the side surface of the storage section 310. This recess 351 is a portion where the legs of a cover member (described later) are disposed, and extends linearly from an end 352 of the side wall 350 toward the outer wall 330 so as to follow the legs. Furthermore, the end 352 aligned linearly with the recess 351 is recessed more toward the outer wall 330 than the adjacent end parts 352 on either side, forming a recessed mounting portion 353. This mounting portion 353 is a portion where the fixing portions of the legs of the cover member (described later) are clamped and fixed.

[0027] Additionally, mounting protrusions 400 are provided on the inner surfaces of the fixing portions 320 on both sides of the housing segment 300, protruding inward. The mounting protrusions 400 include a base end 410 connected to the fixing portion 320 and a tip end 420 protruding from the base end 410. The base end 410 of the mounting protrusion 400 has a generally oval shape in plan view, and is shaped to closely match the shape of the mounting hole 130 of the fuse element 100 so that it can be inserted through the mounting hole 130. Furthermore, the tip end 420 of the mounting protrusion 400 is configured to be able to be inserted through the fixing hole 260 of the housing segment 200. The upper end 411 of the base end 410 is inclined, making it easier to insert through 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 has a substantially circular shape in a plan view, and is configured so as to be able to be inserted into the first fixing hole 261 of the fixing hole 260 of the housing segment 200. Furthermore, the upper end 421 of the tip portion 420 is inclined, making it easier to insert into the fixing hole 260 of the housing segment 200.

[0028] As shown in FIG. 5 , the cross-sectional area S1 of the base end 410 of the mounting protrusion 400 is larger than the cross-sectional area S2 of the tip end 420 of the mounting protrusion 400. When the fuse 900 is assembled, as described below, the mounting protrusion 400 extends perpendicular to the longitudinal direction P2 of the fuse element 100. The axis P3 of the height direction of the mounting protrusion 400 is perpendicular to the longitudinal direction P2 of the fuse element 100. As shown in FIG. 5( b), the cross-sectional area S1 of the base end 410 of the mounting protrusion 400 is the cross-sectional area obtained when the base end 410 is cut in a cross section perpendicular to the axis P3. As shown in FIG. 5( c), the cross-sectional area S2 of the tip end 420 of the mounting protrusion 400 is the cross-sectional area obtained when the tip end 420 is cut in a cross section perpendicular to the axis P3.

[0029] Although the base end 410 of the mounting projection 400 has a generally oval cross section, this is not limited thereto and may have any cross-sectional shape, such as a generally rectangular shape, as long as it can be inserted into the mounting hole 130 of the fuse element 100. Furthermore, although the tip end 420 of the mounting projection 400 has a generally circular cross section, this is not limited thereto and may have any cross-sectional shape, such as a generally square shape, as long as it can be inserted into the fixing hole 260 of the housing segment 200.

[0030] Next, the cover member 600 of the fuse 900 according to the present invention will be described with reference to Fig. 6. Fig. 6(a) is a perspective view of the cover member 600, and Fig. 6(b) is a plan view of the cover member 600.

[0031] As shown in FIG. 6 , the cover member 600 is made of a transparent or translucent synthetic resin and includes a flat main body 610 and legs 620 extending laterally and downward from both sides of the main body 610. The main body 610 is configured to overlap with the viewing window 240 of the housing segment 200 and includes a protrusion 611 disposed within the viewing window 240. The main body 610 is transparent or translucent so that the fusing portion 120 of the fuse element 100 housed within the housing portion 210 can be seen from the outside. Mounting holes 612 are provided at the four corners of the main body 610, into which the protrusions 231 of the housing segment 200 are inserted. The main body 610 also includes protrusions 613 protruding from the surface of the main body 610.

[0032] 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 include 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 portion 623 that protrudes laterally. Although the legs 620 are provided one on each side in the center of the main body 610, the present invention is not limited to this. The legs 620 may be provided at each of the four corners of the main body 610 (four in total), or any number of legs 620 may be provided at any location.

[0033] Next, a description will be given of how to assemble the fuse 900 according to the present invention with reference to Figures 7 and 8. Figure 7(a) is a perspective view of the state in which the cover member 600 is attached to the housing segment 300, Figure 7(b) is a perspective view of the state in which the fuse element 100 is attached to the housing segment 300 and the cover member 600 and the housing segment 200 are 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.

[0034] As shown in FIG. 7A , the cover member 600 is attached to the housing segment 300 in the accommodation portion 310 inside the housing segment 300 so as to overlap the viewing window 340 of the housing segment 300. Specifically, with the cover member 600 turned upside down, the main body 610 of the cover member 600 is placed over the viewing window 340, and the protrusions 331 of the housing segment 300 are inserted into the mounting holes 612 of the main body 610 to attach the cover member 600 to the housing segment 300. The fixing portions 623 of the legs 620 of the cover member 600 rest on the recessed mounting portions 353 in the side walls 350 of the housing segment 300. Furthermore, because the outer surfaces of the legs 620 of the cover member 600 are accommodated in the recesses 351 in the side walls 350 of the housing segment 300, the portions of the legs 620 that protrude into the accommodation portion 310 can be reduced. Therefore, the legs 620 of the cover member 600 are prevented from narrowing the space within the accommodating section 310, and the space within the accommodating section 310 can be kept as large as possible, thereby preventing the internal pressure within the housing 500 from becoming excessively high when the fusing section 120 of the fuse element 100 melts, and avoiding damage to the housing 500.

[0035] 7(b), the fuse element 100 is attached to the housing segment 300 with the cover member 600 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 into the mounting hole 130 of the fuse element 100. The fusing portion 120 of the fuse element 100 is disposed within the accommodation portion 310 of the housing segment 300.

[0036] Next, the cover member 600 is attached to the housing segment 200 in the accommodating portion 210 inside the housing segment 200. The attachment method is the same as the method for attaching the cover member 600 to the housing segment 300, as shown in FIG. 7A . The housing segment 200 with the cover member 600 attached is then attached to the housing segment 300 so as to sandwich the fuse element 100. Specifically, the fixing portion 220 of the housing segment 200 is placed on top of the terminal portion 110 of the fuse element 100, and the terminal portion 110 of the fuse element 100 is sandwiched between the fixing portion 220 of the housing segment 200 and the fixing portion 320 of the housing segment 300. The tip portion 420 of the attachment projection 400 is then inserted into the fixing hole 260 of the housing segment 200. As a result, as shown in Figure 8 (a), the housing 500 consisting of the housing split pieces 200 and 300 is connected to the fuse element 100 with the fusing portion 120 of the fuse element 100 housed inside.

[0037] As shown in FIG. 8( a), the tip 420 of the mounting projection 400 protrudes from the fixing hole 260 of the housing segment 200, and is then heated and crushed. The heated and crushed tip 420 (hereinafter referred to as the head 422) is then welded to the fixing portion 220 around the fixing hole 260 (a process known as crimping), firmly securing the housing segment 200 and the housing segment 300 together. Furthermore, because the upper end 421 of the tip 420 is inclined, the upper end 421 has a smaller volume and is more easily melted. Therefore, the upper end 421 of the tip 420 is easier to heat and crush, and the welding time is shorter. Furthermore, the crushed head 422 is prevented from protruding from the fixing portion 220. As shown in FIG. 8( b), the tip 420 of all of the mounting projections 400 is heated and crushed.

[0038] 7(b), the fixing portion 623 of the cover member 600 attached to the upper housing segment 200 is disposed within the mounting portion 353 of the lower housing segment 300 and overlaps the fixing portion 623 of the cover member 600 attached to the lower housing segment 300. Then, as shown in FIG. 8(a), when the housing segments 200 and 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 a vertically stacked state. In this way, the cover member 600 is firmly fixed within the housing 500.

[0039] 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 fusing portion 120 of the fuse element 100 is housed within the housing 500. The fusing portion 120 of the housing 500 can be seen from the outside through the main body portion 610 of the cover member 600 that is placed over the viewing window 340 of the housing 500.

[0040] 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 into the connection hole 111 of the terminal portion 110 of the fuse element 100 and fastening the fuse 900. When a fastening member such as a bolt inserted into the connection hole 111 of the fuse element 100 is rotated during fastening, 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, stress F1 concentrates at the connection point between the fuse element 100 and the housing 500, i.e., the connection point between the mounting hole 130 of the terminal portion 110 and the mounting protrusion 400 of the housing 500, potentially damaging the housing 500. Therefore, in the fuse 900 of the present invention, the mounting hole 130 is shaped like an elongated hole. This increases the area of ​​the connection point between the mounting protrusion 400 and the mounting hole 130 compared to a simple circular hole, thereby increasing the strength of the connection point. As a result, when fastening members such as bolts to fix the fuse 900, damage to the housing 500 can be prevented.

[0041] Furthermore, the base end 410 side of the mounting protrusion 400 is inserted into and directly connected to the mounting hole 130 of the fuse element 100, and is therefore the location most susceptible to stress. For this reason, the cross-sectional area of ​​the base end 410 is made larger to provide greater strength than the tip end 420. On the other hand, the tip end 420 side 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, and therefore the strength of the tip end 420 may be lower than that of the base end 410. In this way, by making the cross-sectional area of ​​the base end 410 of the mounting protrusion 400 larger than the cross-sectional area of ​​the tip end 420, the strength of the mounting protrusion 400 is improved and optimized.

[0042] Furthermore, the claws 112 provided on the terminal portion 110 of the fuse element 100 are provided at positions adjacent to the mounting hole 130 and abut against the inner surface of the housing 500. Therefore, the claws 112 reinforce the area around the mounting hole 130 and prevent the area around the mounting hole 130 from being deformed by the stress F1 concentrated around the area of ​​the mounting hole 130.

[0043] Next, Fig. 9 shows the structure inside the housing 500. Fig. 9(a) is a cross-sectional view taken along CC in Fig. 8(b), Fig. 9(b) is an enlarged cross-sectional view of the periphery of the viewing window 240 in Fig. 9(a), and Fig. 9(c) is a cross-sectional view taken along D-D in Fig. 8(b).

[0044] As shown in Figures 9(a) and 9(b), the protrusion 613 of the cover member 600 is in point contact with the back surface of the outer wall 230 of the housing 500. The protrusion 613 provides a ventilation space X1 between the back surface of the outer wall 230 of the housing 500 and the main body 610 of the cover member 600. Therefore, as shown in Figure 9(b), gas G1 generated within the housing 500 when the fusing portion 120 of the fuse element 100 melts is released from the ventilation space X1 to the outside through the viewing window 240. This prevents the internal pressure of the housing 500 from increasing due to the gas G1, which could result in damage to the housing 500. The protrusion 611 of the cover member 600 is located within the viewing window 240 of the housing 500, but a small gap X2 is provided between the protrusion 611 and the viewing window 240, allowing the gas G1 to be released.

[0045] Furthermore, when the fusing portion 120 of the fuse element 100 melts, the gasified metal constituting the fusing portion scatters within the housing 500 and adheres to the inner surface of the housing 500. If a voltage is applied to the fuse 900 while the gasified metal constituting the fusing portion is continuously adhering to the inner surface of the housing 500, a leakage current is likely to occur within the housing 500. This reduces the insulation performance between the terminals 110, and even after the fusing portion 120 of the fuse element 100 melts, leakage current flows through the inner surface of the housing 500, continuing conduction between the terminals 110, resulting in the problem of melting damage to the housing 500 and the terminals 110.

[0046] 9(a) and 9(b), an air vent space X1 is provided between the back surface side of the outer wall 230 of the housing 500 and the main body 610 of the cover member 600, so that the outer wall 230 of the housing 500 and the main body 610 of the cover member 600 are vertically spaced apart so that the gasified metal constituting the fusing portion is less likely to adhere continuously. Therefore, the air vent space X1 prevents the gasified metal constituting the fusing portion from adhering continuously to the inner surface of the housing 500, and prevents leakage current from occurring within the housing 500.

[0047] 9( a) and 9(c), the leg portions 620 of the cover member 600 protrude inward from the inner surface of the housing 500. Therefore, the leg portions 620 prevent the gasified fusing portion metal from continuously adhering to the inner surface of the housing 500. Specifically, the fusible element metal G2 scattered from the fusing portion 120 of the fuse element 100 to the surroundings adheres to the inner surface 625 of the leg portions 620 and the inner surface of the outer wall 330, but is less likely to adhere to the side surface 626 of the leg portions 620. Therefore, the stepped leg portions 620 having the inner surface 625 and the side surface 626 prevent the gasified fusing portion metal from continuously adhering to the inner surface of the housing 500, thereby preventing leakage current from occurring within the housing 500.

[0048] Furthermore, the fusing portion 120 of the fuse element 100 is located near the center 502 of the housing 500. The leg portions 620 are disposed on the center 502 side between the ends 501 of the housing 500. Therefore, the leg portions 620 can receive the fusible metal G2 scattered from the fusing portion 120 at the positions closest above and below the fusing portion 120. This makes it even more difficult for the fusible metal G2 scattered radially from the fusing portion 120 to adhere to the side surfaces 626 of the leg portions 620 of the cover member 600. As a result, the gasified fusing portion metal is prevented from continuously adhering to the inner surface of the housing 500, preventing leakage current from occurring within the housing 500.

[0049] Furthermore, the cover member 600 has only the minimum number of legs 620 necessary to support the cover member 600, that is, one on each side of the main body 610. This prevents the legs 620 from narrowing the space inside the housing 500 more than necessary, and maintains the space inside the housing 500 as large as possible. This prevents the internal pressure inside the housing 500 from becoming excessively high when the fusing portion 120 of the fuse element 100 melts, and prevents damage to the housing 500.

[0050] Furthermore, leg portions 620 of cover member 600 are provided continuously around the entire periphery of the inner surface of housing 500 via main body portion 610. Main body portion 610 protrudes inward from the inner surface of housing 500, preventing the gasified metal constituting the fusing portion from continuously adhering to the inner surface of housing 500. As a result, the gasified metal constituting the fusing portion is reliably prevented from continuously adhering around the entire periphery of the inner surface of housing 500, preventing the occurrence of leakage current within housing 500.

[0051] Furthermore, cover member 600 is subjected to outward pressure by gas G1 that is generated when fusing portion 120 melts. However, because cover member 600 is disposed inside housing 500, cover member 600 is unlikely to come off housing 500 even when pressure is applied. Although cover member 600 is disposed inside housing 500, cover member 600 may be attached to the outside of housing 500 as long as cover member 600 is configured to be unlikely to come off housing 500.

[0052] Note that, although a protrusion 613 provides ventilation space X1 between the back surface side of outer wall 230 of housing 500 and main body 610 of cover member 600, the present invention is not limited to this. If protrusion 613 were not provided, the back surface side of outer wall 230 of housing 500 and main body 610 of cover member 600 would come into contact. However, to form ventilation space X1, a groove 614 is provided in main body 610 of cover member 600 instead of protrusion 613. Groove 614 is recessed from the surface of main body 610, with one end 615 of groove 614 communicating with the interior of housing 500 and the other end 616 of groove 614 communicating with viewing window 240. Therefore, groove 614 forms ventilation space X1 that connects the inside and outside of housing 500. Then, within the housing 500, gas G1 generated when the fusing portion 120 of the fuse element 100 melts 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.

[0053] Furthermore, if the protrusion 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 with each other. However, to form the 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 protrusion 613. The groove 617 is recessed from the back surface of the outer wall 230 of the housing 500, with one end 618 of the groove 617 communicating with the interior of the housing 500 and the other end 619 of the groove 617 communicating with the viewing window 240. Therefore, the groove 617 forms the ventilation space X1 that connects the inside and outside of the housing 500. When the fusing portion 120 of the fuse element 100 melts within the housing 500, the gas G1 generated 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 via the viewing window 240.

[0054] Furthermore, the fuse of the present invention is not limited to the above examples, and various modifications and combinations are possible within the scope of the claims and the scope of the embodiments, and these modifications and combinations are also included in the scope of rights.

Claims

1. A fuse comprising a fuse element and a housing that houses a melting portion of the fuse element, wherein the housing has a viewing window located opposite the melting portion, and a cover member is disposed inside the housing that overlaps with the viewing window, and the cover member has a main body that overlaps with the viewing window and legs connected to the main body, and the legs protrude inward from the inner surface of the housing.

2. The fuse according to claim 1, wherein said legs are provided on both sides of said body.

3. A fuse as claimed in claim 1 or 2, wherein the legs are arranged towards the centre of the housing.

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