Protection Elements

Abstract

To provide a protection element that quickly extinguishes arc discharge generated when a fuse element melts (i.e., extinguishing the arc).SOLUTION: A protection element 100 includes: a fuse element 2 energized in a first direction extending from a first end 21 toward a second end 22; a pair of shielding members 3 each including a plate-like portion whose first surface is arranged to face a fuse element 2 and whose second surface is arranged in contact with a rotating axis 33 extending in a second direction that intersects the first direction, and in which a first area and a second area divided at the contact position between the plate-shaped portion and the rotating axis 33, are different from each other in terms of area viewed from the fuse element 2, of the plate-like portion; and a case 6 provided therein with an accommodating portion 60 in which the fuse element 2 and the pair of shielding members 3 are accommodated. The first surface is pressed by pressure increase in the accommodating portion 60 due to arc discharge that occurs when the fuse element 2 melts, and the pair of shielding members 3 rotates around the rotation axis 33, and the pair of shielding members 3 divides an inside of the accommodating portion 60.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a protection element. [Background technology]

[0002] Conventionally, there are fuse elements that generate heat and melt to interrupt a current path when a current exceeding the rated current flows through the current path. Protective devices (fuse elements) equipped with fuse elements are used in a wide range of fields, such as electric vehicles.

[0003] For example, Patent Document 1 describes a fuse in which a large overcurrent flows through the fuse, causing the fusible element to turn into metal vapor, and an arc discharge occurs. This causes the pressure increase in the large space to be utilized to move the interrupter in the direction from the large space to the small space, and the interrupter closes the connecting hole. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-032489 Summary of the Invention [Problem to be solved by the invention]

[0005] In high-voltage protective devices, when a fuse element melts, an arc discharge can occur. This can cause the fuse element to melt over a wide area, resulting in vaporized metal being scattered. This can create new electrical paths or adhere to nearby electronic components, such as terminals. The present invention has been made in view of the above circumstances, and has as its object to provide a protection element that quickly extinguishes (extinguishes) an arc discharge that occurs when a fuse element melts. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention proposes the following means.

[0007] [1] A fuse element that is energized in a first direction from a first end to a second end; a shielding member made of an insulating material, the shielding member having a plate-shaped portion having a first surface facing the fuse element and a second surface in contact with a rotation axis extending in a second direction intersecting the first direction, the area of ​​the plate-shaped portion as viewed from the fuse element being divided at a contact position between the plate-shaped portion and the rotation axis, the first area and the second area being different from each other; a case made of an insulating material and having an accommodating portion therein for accommodating the fuse element and the shielding member, a protection element in which an arc discharge generated when the fuse element melts causes a pressure increase inside the accommodating portion, which presses the first surface, causing the shielding member to rotate around the rotation axis, and the inside of the accommodating portion is divided by the shielding member.

[0008] [2] The protection element according to [1], wherein the surface of the accommodating portion facing the fuse element has a shielding member accommodating groove for accommodating a part of the rotated shielding member.

[0009] [3] The protection element according to [1] or [2], wherein the fuse element has a constricted portion between the first end and the second end, and the cross-sectional area of ​​the constricted portion in the second direction is smaller than the cross-sectional areas of the first end and the second end in the second direction. [4] The protection element according to [3], wherein the width in the second direction at the constricted portion is narrower than the width in the second direction of the first end portion and the second end portion.

[0010] [5] The protection element according to any one of [1] to [4], wherein the fuse element is composed of a laminate in which an inner layer made of a low-melting-point metal and an outer layer made of a high-melting-point metal are laminated in the thickness direction. [6] The low-melting-point metal is made of Sn or a metal containing Sn as a main component, The protection element according to [5], wherein the high-melting-point metal is made of Ag or Cu, or a metal containing Ag or Cu as a main component. [7] The protection element according to any one of [1] to [6], wherein the fuse element has a bent portion bent along a direction intersecting the first direction.

[0011] [8] The protection element according to any one of [1] to [7], wherein one or both of the shielding member and the case is made of any one of resin materials selected from nylon-based resin, fluorine-based resin, and polyphthalamide resin. [9] The protection element according to [8], wherein the resin material is formed of a resin material having a tracking resistance index CTI of 600 V or more.

[10] The protection element according to [8], wherein the nylon resin is a resin that does not contain a benzene ring.

[0012]

[11] The first end is electrically connected to a first terminal, and the second end is electrically connected to a second terminal; The protection element according to any one of [1] to

[10] , wherein a portion of the first terminal and a portion of the second terminal are exposed from the case.

[12] The protection element according to any one of [1] to

[11] , further comprising a pressing means for applying a force to the second surface of the plate-shaped portion in the rotational direction of the shielding member.

[0013]

[13] The shielding member comprises a first shielding member and a second shielding member having the same shape as the first shielding member, The protection element according to any one of [1] to

[12] , wherein the first shielding member and the second shielding member are arranged symmetrically in the first direction with respect to the center of the fuse element in the first direction.

[14] The fuse element has a disconnection portion between the first end and the second end, the first shielding member and the second shielding member are disposed symmetrically in the first direction with respect to the cutting portion, the second shielding member is disposed opposite to the surface of the fuse element opposite to the surface facing the first shielding member, The protection element according to

[13] , wherein the rotation direction of the first shielding member and the rotation direction of the second shielding member are opposite directions.

[0014]

[15] The case comprises a first case and a second case having the same shape as the first case, The protection element according to any one of [1] to

[14] , wherein the first case and the second case are disposed opposite to each other with respect to the fuse element.

[16] A part of the case is covered with a cover, an internal pressure buffer space surrounded by an outer surface of the case and an inner surface of the cover is provided; the case has an air hole penetrating the case and communicating the storage section with the internal pressure buffer space, The protection element according to any one of [1] to

[15] , wherein the volume of the internal pressure buffer space is equal to or larger than the volume of the fuse element.

[0015]

[17] The rotation shaft is formed by a step in a recess formed in the housing portion, The protection element according to any one of [1] to

[16] , wherein the shielding member rotates in a direction away from the rotation axis, at both ends of the first surface of the plate-shaped portion in the first direction.

[0016]

[18] The protection element according to any one of [1] to

[17] , wherein a heat generating member for heating the fuse element is provided on the first surface of the plate-shaped portion.

[19] The protection element according to

[18] , wherein the heat generating member includes an element connecting electrode electrically connected to the fuse element.

[20] The protection element according to

[19] , wherein the heat generating member comprises a heat generating portion made of a resistor and power supply electrodes electrically connected to both ends of the heat generating portion that face each other across the center of the heat generating portion.

[0017]

[21] The heat generating portion is provided on an insulating substrate, an insulating layer is provided on the heat generating portion; The protection element according to

[20] , wherein the element connection electrode is provided at a position on the insulating layer where it at least partially overlaps with the heat generating portion.

[22] The heat generating portion is provided on an insulating substrate, an insulating layer is provided on the heat generating portion; The protection element according to

[20] , wherein the element connection electrode is provided on the surface of the insulating substrate opposite the heat generating portion, at a position where it at least partially overlaps the heat generating portion. [Effects of the Invention]

[0018] In the protection element of the present invention, the pressure inside the housing increases due to the arc discharge that occurs when the fuse element melts, and the first surface of the plate-shaped portion of the shielding member is pressed. This causes the shielding member to rotate about a rotation axis that extends in a direction intersecting the current flow direction of the fuse element, and the inside of the housing that houses the fuse element and the shielding member is divided by the shielding member. As a result, the cut surfaces or fused surfaces of the cut or melted fuse element are insulated from each other by the shielding member, and the current path is interrupted. As a result, the arc discharge that occurs when the fuse element melts is quickly extinguished (extinguished). [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view showing the overall structure of a protection element 100 according to the first embodiment. [Figure 2] FIG. 2 is an exploded perspective view showing the overall structure of the protection element 100 shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view of the protection element 100 according to the first embodiment taken along the line AA′ shown in FIG. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing a part of FIG. [Figure 5] FIG. 5 is a diagram for explaining the operation of the protection element 100 of the first embodiment, and is a cross-sectional view taken along the line AA′ shown in FIG. [Figure 6]FIG. 6 is an enlarged cross-sectional view showing a part of FIG. [Figure 7] FIG. 7 is an enlarged view for explaining a part of the protection element 100 of the first embodiment, and is a perspective view showing the fuse element, the first terminal, and the second terminal. [Figure 8] 8A and 8B are diagrams illustrating the structure of the first shielding member 3a provided in the protection element 100 of the first embodiment. Fig. 8A is a perspective view seen from the housing portion side, and Fig. 8B is a perspective view seen from the fuse element side. [Figure 9] Fig. 9 is a diagram illustrating the structure of the first shielding member 3a provided in the protection element 100 of the first embodiment. Fig. 9(a) is a plan view seen from the fuse element side, Fig. 9(b) is a plan view seen from the accommodating section side, and Figs. 9(c) to 9(e) are side views. [Figure 10] Fig. 10 is a diagram illustrating the structure of the first case 6a provided in the protection element 100 of the first embodiment. Fig. 10(a) is a perspective view seen from the outside, and Fig. 10(b) and Fig. 10(c) are perspective views seen from the housing side. [Figure 11] Fig. 11 is a diagram illustrating the structure of the first case 6a provided in the protection element 100 of the first embodiment. Fig. 11(a) is a plan view seen from the housing side, Fig. 11(b) is a plan view seen from the outside, and Figs. 11(c) to (e) are side views. [Figure 12] Figure 12 is a diagram illustrating the manufacturing process of the protection element 100 of the first embodiment. Figure 12(a) is a perspective view of the second case 6b on which the second shielding member 3b is installed, viewed from the side that becomes the accommodating portion 60, and Figure 12(b) is a perspective view showing the fuse element 2 integrated with the first terminal 61 and the second terminal 62 installed on the second case 6b on which the second shielding member 3b is installed. [Figure 13]13A and 13B are diagrams illustrating the manufacturing process of the protection element 100 of the first embodiment. Fig. 13A is a perspective view showing a state in which the first case 6a is placed on the second case 6b via the fuse element 2, and Fig. 13B is a perspective view showing a state in which the first case 6a and the second case 6b are integrated and housed in the cover 4. [Figure 14] FIG. 14 is a cross-sectional view for explaining a protection element 200 according to the second embodiment, and is a cross-sectional view corresponding to the position where the protection element 100 according to the first embodiment is cut along the line AA′ shown in FIG. [Figure 15] FIG. 15 is a diagram for explaining the operation of the protection element 200 of the second embodiment, and is a cross-sectional view at a position corresponding to the cross-sectional view shown in FIG. [Figure 16] Fig. 16 is a diagram illustrating the structure of a first shielding member 3a provided in a protection element 200 of the second embodiment. Fig. 16(a) is a perspective view seen from the accommodating portion side, and Fig. 16(b) is a perspective view seen from the fuse element side. [Figure 17] FIG. 17 is a plan view of the first case 6a provided in the protection element 200 of the second embodiment, as viewed from the housing portion side. [Figure 18] FIG. 18 is a perspective view showing the overall structure of a protection element 300 according to the third embodiment. [Figure 19] FIG. 19 is an exploded perspective view showing the overall structure of the protection element 300 shown in FIG. [Figure 20] FIG. 20 is a cross-sectional view of the protection element 300 according to the third embodiment taken along the line BB′ shown in FIG. [Figure 21] FIG. 21 is a diagram for explaining the operation of the protection element 300 of the third embodiment, and is a cross-sectional view at a position corresponding to the cross-sectional view shown in FIG. [Figure 22] Figure 22 is a drawing for explaining the structure of the first heat generating member 51 provided in the protection element 300 of the third embodiment, where Figure 22(a) is a cross-sectional view seen from the X direction, Figure 22(b) is a cross-sectional view seen from the Y direction, and Figure 22(c) is a plan view. [Figure 23]Figure 23 is a drawing for explaining another example of a heat-generating member, in which Figure 23(a) is a cross-sectional view of heat-generating member 52 as viewed from the X direction, and Figure 23(b) is a cross-sectional view of the center in the Y direction of heat-generating member 52 shown in Figure 23(a) as viewed from the Y direction. Figure 23(c) is a cross-sectional view of heat-generating member 53 as viewed from the X direction, and Figure 23(d) is a cross-sectional view of the center in the Y direction of heat-generating member 53 shown in Figure 23(c) as viewed from the Y direction. [Figure 24] FIG. 24 is an enlarged view for explaining a part of the protection element 300 of the third embodiment, and is a perspective view showing the fuse element, the first terminal, the second terminal, the heat-generating member, the power supply line, and the power supply lead line. [Figure 25] Figure 25 is a diagram illustrating the structure of a first shielding member 3a provided in a protection element 300 of the third embodiment. Figure 25(a) is a perspective view seen from the accommodating section side, and Figure 25(b) is a perspective view seen from the fuse element side. [Figure 26] Figure 26 is a diagram illustrating a manufacturing process for a protection element 300 of the third embodiment. Figure 26(a) is a perspective view showing a state in which a member in which the fuse element 2, the first terminal 61, the second terminal 62, the first heat-generating member 51, the second heat-generating member 56, the power supply lines 54a, 54b, 55a, 55b, and the conductive members 54d, 55d are integrated is placed on the second case 6b on which the second shielding member 3b is placed. Figure 26(b) is a perspective view showing a state in which the first case 6a is placed on the second case 6b via the fuse element 2. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for the sake of clarity, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate modifications can be made within the scope of the effects of the present invention.

[0021] [First embodiment] (protective element) 1 to 11 are schematic diagrams showing a protection element according to a first embodiment. In the drawings used in the following description, the direction indicated by X is the current-carrying direction (first direction) of the fuse element. The direction indicated by Y is a direction perpendicular to the X direction (first direction), and the direction indicated by Z is a direction perpendicular to the X direction and the Y direction.

[0022] FIG. 1 is a perspective view showing the overall structure of a protection element 100 according to the first embodiment. FIG. 2 is an exploded perspective view showing the overall structure of the protection element 100 shown in FIG. 1. FIG. 3 is a cross-sectional view of the protection element 100 according to the first embodiment taken along line AA' shown in FIG. 1. FIG. 4 is an enlarged cross-sectional view showing a portion of FIG. 3. FIG. 5 is a diagram for explaining the operation of the protection element 100 according to the first embodiment, and is a cross-sectional view taken along line AA' shown in FIG. 1. FIG. 6 is an enlarged cross-sectional view showing a portion of FIG. 5.

[0023] As shown in Figures 1 to 3, the protection element 100 of this embodiment includes a fuse element 2, a shielding member 3, a case 6 having an internal storage section 60 for storing the fuse element 2 and the shielding member 3, and a cover 4 that covers the Y-direction and Z-direction side surfaces of the case 6. In the protective element 100 of this embodiment, the pressure inside the accommodating portion 60 increases due to the arc discharge that occurs when the fuse element 2 melts, causing the shielding member 3 to rotate around the rotation axis 33, as shown in Figures 5 and 6, and the inside of the accommodating portion 60 is divided by the shielding member 3.

[0024] (Fuse element) FIG. 7 is an enlarged view for explaining a part of the protection element 100 of the first embodiment, and is a perspective view showing the fuse element, the first terminal, and the second terminal. 7, the fuse element 2 is strip-shaped and has a first end 21, a second end 22, and a cutting portion 23 consisting of a constricted portion provided between the first end 21 and the second end 22. Electricity flows through the fuse element 2 in the X direction (first direction), which is the direction from the first end 21 to the second end 22. 3 and 7, the first end 21 is electrically connected to a first terminal 61. The second end 22 is electrically connected to a second terminal 62.

[0025] The first terminal 61 and the second terminal 62 may have substantially the same shape as shown in Fig. 7, or may have different shapes. The thickness of the first terminal 61 and the second terminal 62 is not particularly limited, but may be approximately 0.3 to 1.0 mm. The thickness of the first terminal 61 and the second terminal 62 may be the same as or different from each other, as shown in Fig. 3.

[0026] 1 to 3 and 7, the first terminal 61 has an external terminal hole 61a. The second terminal 62 has an external terminal hole 62a. One of the external terminal hole 61a and the external terminal hole 62a is used for connecting to the power supply side, and the other is used for connecting to the load side. The external terminal hole 61a and the external terminal hole 62a can be through holes that are approximately circular in plan view, as shown in FIG.

[0027] The first terminal 61 and the second terminal 62 may be made of, for example, copper, brass, nickel, or the like. From the viewpoint of increasing rigidity, brass is preferably used as the material for the first terminal 61 and the second terminal 62, and from the viewpoint of reducing electrical resistance, copper is preferably used. The first terminal 61 and the second terminal 62 may be made of the same material or different materials.

[0028] The shape of the first terminal 61 and the second terminal 62 is not particularly limited as long as it can engage with a terminal on the power supply side or a terminal on the load side (not shown), and may be, for example, a claw shape with a partial open portion, or may have flanges (indicated by reference numerals 61c and 62c in FIG. 7) that widen on both sides toward the fuse element 2 at the end connected to the fuse element 2. When the first terminal 61 and the second terminal 62 have flanges 61c and 62c, the first terminal 61 and the second terminal 62 are less likely to come off the case 6, resulting in a protective element 100 with good reliability and durability.

[0029] The fuse element 2 shown in Fig. 7 has a substantially uniform thickness (length in the Z direction). The thickness of the fuse element 2 may be uniform, as shown in Fig. 3, or may vary partially. An example of a fuse element having a partially varying thickness is one in which the thickness gradually increases from the cutting portion 23 toward the first end 21 and the second end 22. In such a fuse element, when an overcurrent flows, the cutting portion 23 becomes a heat spot, and the cutting portion 23 is preferentially heated and softened, resulting in more reliable cutting. The thickness of the fuse element 2 can be, for example, 0.03 to 1.0 mm, and preferably 0.2 to 0.5 mm.

[0030] As shown in Fig. 7, the fuse element 2 has a generally rectangular shape in a plan view. As shown in Fig. 7, the width 21D in the Y direction at the first end 21 and the width 22D in the Y direction at the second end 22 are generally the same. Therefore, the width in the Y direction of the fuse element 2 shown in Fig. 7 means the widths 21D and 22D in the Y direction of the first end 21 and the second end 22.

[0031] 1, 3, and 7, the first end 21 of the fuse element 2 is arranged to overlap the first terminal 61 in a plan view. In addition, the second end 22 of the fuse element 2 is arranged to overlap the second terminal 62 in a plan view. 7, the length of the first end 21 in the X direction extends from the region overlapping with the first terminal 61 in a plan view toward the cutting portion 23. Also, as shown in FIG. 7, the length of the second end 22 in the X direction extends from the region overlapping with the second terminal 62 in a plan view toward the cutting portion 23. In the fuse element 2 shown in FIG. 7, the length of the second end 22 in the X direction and the length of the first end 21 in the X direction are approximately the same. In other words, in this embodiment, the cutting portion 23 is disposed at the center of the fuse element 2 in the X direction.

[0032] As shown in FIG. 7 , a first connecting portion 25 having a generally trapezoidal shape in plan view is disposed between the cutting portion 23 and the first end 21. The longer parallel sides of the first connecting portion 25 having a generally trapezoidal shape in plan view are connected to the first end 21. A second connecting portion 26 having a generally trapezoidal shape in plan view is disposed between the cutting portion 23 and the second end 22. The longer parallel sides of the second connecting portion 26 having a generally trapezoidal shape in plan view are connected to the second end 22. The first connecting portion 25 and the second connecting portion 26 are symmetrical with respect to the cutting portion 23. As a result, the width of the fuse element 2 in the Y direction gradually increases from the cutting portion 23 toward the first end 21 and the second end 22. As a result, when an overcurrent flows through the fuse element 2, the cutting portion 23 becomes a heat spot, which preferentially heats up and softens the cutting portion 23, allowing it to be easily cut or melted.

[0033] 7, the width 23D in the Y direction of the cutting portion 23 of the fuse element 2 is narrower than the widths 21D and 22D in the Y direction of the first end 21 and the second end 22. As a result, the cross-sectional area of ​​the cutting portion 23 in the Y direction is narrower than the cross-sectional area of ​​the region of the fuse element 2 other than the cutting portion 23. As a result, the cutting portion 23 is more easily cut or melted than the region between the cutting portion 23 and the first end 21 and the region between the cutting portion 23 and the second end 22.

[0034] In this embodiment, the fuse element 2 has been described as having a cutting portion 23 consisting of a constricted portion whose Y-direction width 23D is narrower than the Y-direction widths 21D, 22D of the first end 21 and the second end 22, as shown in Figure 7. However, the fuse element may have the Y-direction width of the cutting portion the same as that of the first end and the second end, and is not limited to fuse elements whose Y-direction width of the cutting portion is narrower than that of the first end and the second end. For example, instead of the fuse element 2 shown in Fig. 7, it is also possible to provide a linear or strip-shaped fuse element having a uniform cross-sectional area in the Y direction. In this case, the cross-sectional area of ​​the cut portion of the fuse element in the Y direction (second direction) is the same as the cross-sectional area of ​​the region of the fuse element other than the cut portion.

[0035] 3 and 7 , the fuse element 2 has two bent portions, a first bent portion 24a and a second bent portion 24b, formed by bending a strip-shaped member twice at approximately right angles along the Y direction. The first bent portion 24a is a step formed along the edge of the area where the first end portion 21 and the first terminal 61 overlap in a planar view, covering the end face of the first terminal 61. The second bent portion 24b is a step formed along the edge of the area where the second end portion 22 and the second terminal 62 overlap in a planar view, covering the end face of the second terminal 62. The first bent portion 24a and the second bent portion 24b relieve stress associated with thermal expansion and contraction of the fuse element 2 extending in the X direction, improving the durability of the fuse element 2.

[0036] In this embodiment, as shown in FIG. 3, by having the first bent portion 24a and the second bent portion 24b, the surface of the first terminal 61 on which the first end 21 is not stacked, the surface of the second terminal 62 on which the second end 22 is not stacked, and one surface at the center of the fuse element 2 (the lower surface in FIG. 3) are arranged on approximately the same plane.

[0037] In this embodiment, as shown in FIG. 7, the bending portion is described using the first bending portion 24a and the second bending portion 24b formed by bending a strip-shaped material along the Y direction. However, the direction in which the strip-shaped material forming the bending portion is bent may be any direction intersecting the X direction, and is not limited to the Y direction. In addition, in this embodiment, the bending portions are described using the first bending portion 24a and the second bending portion 24b, in which the strip-shaped material is bent twice at approximately right angles, as examples, but the angle and number of times the strip-shaped material forming the bending portions is bent are not particularly limited.

[0038] In addition, in this embodiment, an example has been described in which the first bent portion 24a is provided on the first end 21 side of the fuse element 2 and the second bent portion 24b is provided on the second end 22 side, but the number of bent portions provided on the fuse element may be one, three or more, or the fuse element may not have any bent portions.

[0039] Materials used for known fuse elements, such as metal materials containing alloys, can be used as the material for the fuse element 2. Specifically, alloys such as Pb85% / Sn and Sn / Ag3% / Cu0.5% can be used as the material for the fuse element 2.

[0040] The fuse element 2 is preferably a laminate in which an inner layer made of a low-melting-point metal and an outer layer made of a high-melting-point metal are laminated in the thickness direction. Such a fuse element 2 is preferable because it has good solderability when the first terminal 61 and the second terminal 62 are soldered to the fuse element 2. When the fuse element 2 is composed of a laminate in which an inner layer made of a low-melting-point metal and an outer layer made of a high-melting-point metal are laminated in the thickness direction, it is preferable in terms of the current interruption characteristics of the fuse element 2 that the volume of the low-melting-point metal is greater than the volume of the high-melting-point metal.

[0041] The low-melting-point metal used for the fuse element 2 is preferably Sn or a metal containing Sn as its main component. Since the melting point of Sn is 232°C, a metal containing Sn as its main component has a low melting point and softens at low temperatures. For example, the solidus of a Sn / 3% Ag / 0.5% Cu alloy is 217°C.

[0042] It is preferable to use Ag or Cu, or a metal containing Ag or Cu as the main component, as the high-melting-point metal used as the material for the fuse element 2. For example, since the melting point of Ag is 962°C, a layer made of a metal containing Ag as the main component maintains its rigidity at temperatures at which a layer made of a low-melting-point metal becomes soft. Furthermore, when a metal containing Ag as a main component is formed as the outer layer, the resistance value of the fuse element 2 can be efficiently reduced, and the rated current as a protective element can be set high, which is preferable.

[0043] When the fuse element 2 is made of a laminate in which an inner layer made of a low-melting point metal and an outer layer made of a high-melting point metal are stacked in the thickness direction, and has a cutting portion 23 made of a constricted portion whose Y-direction width 23D is narrower than the Y-direction widths 21D and 22D of the first end 21 and the second end 22, an outer layer may or may not be formed on the Y-direction side of the cutting portion 23.

[0044] The fuse element 2 in the protection device 100 of this embodiment preferably has a melting temperature of 600° C. or less, and more preferably 400° C. or less. If the melting temperature is 600° C. or less, the arc discharge that occurs when the fuse element 2 melts becomes even smaller in scale. Only one fuse element 2 may be used, or multiple fuse elements 2 may be stacked as needed. In this embodiment, an example in which two fuse elements 2 are stacked will be described, but only one fuse element or three or more fuse elements may also be used.

[0045] The fuse element 2 can be manufactured by a known method. For example, if the fuse element 2 is composed of a laminate in which an inner layer made of a low-melting-point metal and an outer layer made of a high-melting-point metal are stacked in the thickness direction, and no outer layer is formed on the Y-direction side of the cutting portion 23 consisting of the constricted portion, it can be manufactured by the following method. First, a metal foil made of a low-melting-point metal is prepared. Next, a high-melting-point metal layer is formed on the entire surface of the metal foil using a plating method to form a laminate. The laminate is then cut into a predetermined shape having the cutting portion 23 consisting of the constricted portion. Through the above steps, a fuse element 2 consisting of a laminate with a three-layer structure is obtained.

[0046] When manufacturing a fuse element 2 made of the above-mentioned laminate, having a cut portion 23 made of a constricted portion, and having an outer layer formed on the Y-direction side of the cut portion 23, it can be manufactured, for example, by the method shown below. That is, a metal foil made of a low-melting-point metal is prepared and cut into a predetermined shape. Next, a high-melting-point metal layer is formed on the entire surface of the metal foil using a plating method to form a laminate. Through the above steps, a fuse element 2 made of a laminate with a three-layer structure is obtained.

[0047] (Shielding member) 1 to 6, the shielding member 3 is made up of a first shielding member 3a and a second shielding member 3b that has the same shape as the first shielding member 3a. In this embodiment, since the first shielding member 3a and the second shielding member 3b have the same shape, they are preferably manufactured using the same material, which reduces the number of types of parts to be manufactured. The first shielding member 3a and the second shielding member 3b may also be made of different materials. In this embodiment, an example will be described in which there are two shielding members 3, a first shielding member 3a and a second shielding member 3b, but the shielding member 3 may consist of only one of the first shielding member 3a and the second shielding member 3b.

[0048] In this embodiment, the shielding member 3 includes two members, a first shielding member 3a and a second shielding member 3b, and therefore the first shielding member 3a and the second shielding member 3b rotate due to a pressure increase inside the accommodating portion 60 when the fuse element 2 melts. The first shielding member 3a divides the inside of the accommodating portion 60, and the second shielding member 3b divides the inside of the accommodating portion 60. Therefore, when the shielding member 3 includes two members, the first shielding member 3a and the second shielding member 3b, arc discharge that occurs when the fuse element 2 melts is extinguished (extinguished) more quickly and reliably than when only one of the first shielding member 3a and the second shielding member 3b is used.

[0049] In this embodiment, as shown in FIGS. 3 and 4 , the second shielding member 3b and the first shielding member 3a are disposed in a point-symmetrical position with respect to the X-direction center of the fuse element 2 in the AA′ cross section. That is, the first shielding member 3a and the second shielding member 3b are disposed symmetrically in the X direction with respect to the X-direction center of the fuse element 2. Therefore, in the protection element 100 of this embodiment, even if the first shielding member 3a and the second shielding member 3b rotate simultaneously due to a pressure increase within the accommodating portion 60 when the fuse element 2 melts, they do not interfere with each other and their rotational movements are not hindered. Therefore, the accommodating portion 60 is more reliably divided by the first shielding member 3a and the second shielding member 3b at two locations in the X direction within the accommodating portion 60. Furthermore, the first shielding member 3a and the second shielding member 3b, before rotational movement, can be stably disposed in predetermined positions within the accommodating portion 60 together with the fuse element 2, resulting in a highly reliable protection element 100.

[0050] Moreover, in this embodiment, the fuse element 2 has a cutting portion 23 between the first end 21 and the second end 22, and as shown in Figures 5 and 6, when the first shielding member 3a and the second shielding member 3b rotate, the inside of the accommodating portion 60 is divided by the first shielding member 3a and the second shielding member 3b at two adjacent locations in the X direction within the accommodating portion 60 that sandwich the cutting portion 23. As a result, the arc discharge that occurs when the fuse element 2 melts is extinguished (extinguished) more quickly and reliably.

[0051] In this embodiment, the structure of the first shielding member 3a will be described with reference to Figures 8 and 9. The structure of the second shielding member 3b is the same as that of the first shielding member 3a, and therefore description thereof will be omitted. Fig. 8 is a diagram illustrating the structure of the first shielding member 3a provided in the protection element 100 of the first embodiment. Fig. 8(a) is a perspective view seen from the accommodating section side, and Fig. 8(b) is a perspective view seen from the fuse element side. Fig. 9 is a diagram illustrating the structure of the first shielding member 3a provided in the protection element 100 of the first embodiment. Fig. 9(a) is a plan view seen from the fuse element side, Fig. 9(b) is a plan view seen from the accommodating section side, and Figs. 9(c) to 9(e) are side views.

[0052] 1 to 9, the first shielding member 3a has a plate-shaped portion 30. The plate-shaped portion 30 is generally rectangular in plan view, and has a first surface 31 arranged opposite the fuse element 2 and a second surface 32 arranged opposite the housing portion 60 of the case 6, as shown in FIG. The first surface 31 of the plate-shaped portion 30 is disposed in close proximity to or in contact with the fuse element 2, and is preferably disposed in contact with the fuse element 2 as shown in Figures 3 and 4, and more preferably the entire surface of the first surface 31 is disposed in contact with the fuse element 2. When the first surface 31 and the fuse element 2 are disposed in contact with each other, the arc discharge that occurs when the fuse element 2 melts becomes even smaller in scale.

[0053] 3 and 4, the second surface 32 of the plate-shaped portion 30 is disposed in contact with a rotation axis 33 extending in the Y direction. In this embodiment, as shown in FIGS. 3 and 4, the rotation axis 33 is formed by a step in a recess 68 formed in the housing portion 60 of the case 6.

[0054] 4, of the two ends in the X direction on the first surface 31 of the plate-like portion 30 of the first shielding member 3a shown in FIGS. 8(b) and 9, the first end edge 31a closer to the rotation axis 33 is disposed on the inner side of the accommodation portion 60 in the X direction, and the second end edge 31b farther from the rotation axis 33 is disposed on the outer side of the accommodation portion 60 in the X direction. As shown in FIG. 6, as the first shielding member 3a rotates, the first end edge 31a is pressed against the bottom surface of the shielding member accommodation groove 34 provided on the inner surface of the accommodation portion 60. Furthermore, as the first shielding member 3a rotates, the second end edge 31b is accommodated in the recess 68.

[0055] In this embodiment, as shown in FIG. 4, of the two ends in the X direction of the second surface 32 of the plate-like portion 30 of the first shielding member 3a shown in FIGS. 8(a) and 9, the first end edge 32a closer to the rotation axis 33 is positioned inside the X direction of the accommodating portion 60, and the second end face 32b positioned at the second end farther from the rotation axis 33 is positioned outside the X direction of the accommodating portion 60.

[0056] 9(a), the first shielding member 3a has a plate-shaped portion 30 whose area as seen from the fuse element 2 is divided into a first area 30a and a second area 30b at a contact position 33a between the plate-shaped portion 30 and the rotating shaft 33. In this embodiment, as shown in FIG. 9(a), the first area 30a located on the first end side 31a side closer to the rotating shaft 33 is smaller than the second area 30b located on the second end side 31b side farther from the rotating shaft 33.

[0057] As shown in FIGS. 5 and 6 , the first shielding member 3a rotates around the rotation axis 33 due to a pressure increase inside the accommodating portion 60 caused by an arc discharge that occurs when the fuse element 2 melts. In this embodiment, the pressure on the first surface 31 caused by the pressure increase inside the accommodating portion 60 is relatively stronger on the second area 30b, which has a larger area, of the first area 30a and the second area 30b shown in FIG. 9( a), than on the first area 30a, which has a smaller area. Therefore, the pressure on the second end edge 31b of the first surface 31 is stronger than the pressure on the first end edge 31a. Therefore, as shown in FIG. 6 , the first shielding member 3a rotates such that the second end edge 31b, which is located on the outer side of the accommodating portion 60 in the X direction, moves away from the fuse element 2 (moves away from the fuse element 2), and the first end edge 31a, which is located on the inner side of the accommodating portion 60 in the X direction, moves toward the fuse element 2.

[0058] 8(a) and 9, a protrusion 38 is provided in an upright position at the center in the Y direction of the second end face 32b of the second surface 32. The protrusion 38 has a quadrangular prism shape. One of the side surfaces of the protrusion 38 is a flat surface that is continuous with the side surface of the plate-like portion 30 in the X direction. 5 and 6, the protrusion 38 is accommodated in the guide hole 66 when the fuse element 2 is blown, and functions as a guide that rotates the first shielding member 3a to a predetermined position. Therefore, since the first shielding member 3a has the protrusion 38, the first shielding member 3a can easily rotate to a predetermined position when the fuse element 2 is blown. As a result, the rotation of the first shielding member 3a more reliably divides the inside of the accommodation portion 60. In this embodiment, the convex portion 38 is positioned at the center of the Y direction on the second end surface 32b of the second surface 32, so that misalignment of the first shielding member 3a, which rotates when the fuse element 2 blows, is more effectively prevented.

[0059] In this embodiment, as shown in FIGS. 8A and 9, the second end surface 32b of the second surface 32 is an inclined surface that is chamfered to a width corresponding to the dimension of the protrusion 38 in the X direction. Therefore, as shown in FIG. 6, the second end surface 32b of the second surface 32 abuts against the second bottom surface 68d of the recess 68 (described later), preventing the protrusion 38 from entering the guide hole 66 as the first shielding member 3a rotates. This facilitates the first shielding member 3a to rotate to a predetermined position when the fuse element 2 blows. Furthermore, since the recess 68 does not need to be deep to avoid contact between the protrusion 38 and the second bottom surface 68d as the first shielding member 3a rotates, the protection device 100 can be made smaller. Furthermore, since the recess 68 does not need to be deep, the thickness of the case 6 can be ensured, thereby ensuring the strength of the case 6.

[0060] The size of the protrusion 38 is such that it can be accommodated in the recess 68 formed in the accommodation portion 60 before the first shielding member 3a is rotated, as shown in Figures 3 and 4, and can be accommodated in the guide hole 66 formed in the recess 68 when the first shielding member 3a is rotated, as shown in Figures 5 and 6. In this embodiment, the dimension of the protrusion 38 in the X direction and the length from the second surface 32 to the top of the protrusion 38 are approximately the same as the thickness of the plate-like portion 30, and the dimension of the protrusion 38 in the Y direction is longer than the dimension in the X direction.

[0061] In the present embodiment, the case where the protrusions 38 have the above-mentioned quadrangular prism shape has been described as an example, but the shape of the protrusions is not limited to the above-mentioned quadrangular prism shape and may be, for example, a regular quadrangular prism shape, or a shape whose dimension in the Y direction is shorter than its dimension in the X direction. Furthermore, the shape of the protrusions may be, for example, a columnar shape having a cross-sectional shape such as a circular, oval, elliptical, triangular, or hexagonal shape. Furthermore, in this embodiment, an example has been given in which the convex portion 38 is positioned at the center of the second surface 32 in the Y direction, but the position of the convex portion in the Y direction on the second surface 32 does not have to be at the center.

[0062] In addition, in this embodiment, the case where the shielding member has a convex portion has been described as an example, but the convex portion is provided as needed to make it easier to rotate the shielding member to a predetermined position, and does not have to be provided. Even if the shielding member does not have a convex portion, it is preferable that a guide hole 66 be provided in the recess 68 to exhaust gas inside the accommodating portion 60 generated by arc discharge when the fuse element 2 melts to the internal pressure buffering space 71.

[0063] The first shielding member 3a and the second shielding member 3b are made of an insulating material, such as a ceramic material or a resin material. Examples of ceramic materials include alumina, mullite, and zirconia, and it is preferable to use a material with high thermal conductivity such as alumina. When the first shielding member 3a and the second shielding member 3b are made of a material with high thermal conductivity such as a ceramic material, the heat generated when the fuse element 2 is cut can be efficiently dissipated to the outside. Therefore, the continuation of the arc discharge that occurs when the fuse element 2 is cut is more effectively suppressed.

[0064] The resin material is preferably any one selected from polyphenylene sulfide (PPS) resin, nylon resin, fluorine-based resin such as polytetrafluoroethylene, and polyphthalamide (PPA) resin, and particularly preferably nylon resin.

[0065] The nylon-based resin may be an aliphatic polyamide or a semi-aromatic polyamide. When an aliphatic polyamide that does not contain a benzene ring is used as the nylon-based resin, graphite is less likely to be generated even when the first shielding member 3a and / or the second shielding member 3b are burned by an arc discharge that occurs when the fuse element 2 melts, compared to when a semi-aromatic polyamide that has a benzene ring is used. Therefore, by forming the first shielding member 3a and the second shielding member 3b using an aliphatic polyamide, it is possible to prevent the formation of a new electrical path by the graphite generated when the fuse element 2 melts.

[0066] Examples of aliphatic polyamides that can be used include nylon 4, nylon 6, nylon 46, and nylon 66. As the semi-aromatic polyamide, for example, nylon 6T, nylon 9T, etc. can be used.

[0067] Among these nylon-based resins, it is preferable to use a resin that does not contain a benzene ring, such as aliphatic polyamides nylon 4, nylon 6, nylon 46, and nylon 66, and it is more preferable to use nylon 46 or nylon 66 because of their excellent heat resistance. For example, when the shielding member 3, case 6, and cover 4 in the protection element 100 are made of nylon 66, an aliphatic polyamide, the insulation resistance after current interruption is 10 to 10,000 times higher than when they are made of nylon 9T, a semi-aromatic polyamide having a benzene ring.

[0068] The resin material used preferably has a tracking resistance index CTI of 400 V or more, more preferably 600 V or more. The tracking resistance can be determined by a test based on IEC60112. Among resin materials, nylon resins are particularly preferable because they have high tracking resistance (resistance to tracking (carbonized conductive path) breakdown).

[0069] It is preferable to use a resin material with a high glass transition temperature. The glass transition temperature (Tg) of a resin material is the temperature at which it changes from a soft rubbery state to a hard glassy state. When a resin is heated above the glass transition temperature, the molecules become more mobile and it becomes a soft rubbery state. On the other hand, as the resin cools, the molecular movement becomes restricted and it becomes a hard glassy state. The first shielding member 3a and the second shielding member 3b can be manufactured by a known method.

[0070] (case) 1 to 3, the case 6 is substantially cylindrical. The case 6 is made up of a first case 6a and a second case 6b, and is disposed opposite the fuse element 2. A portion of the first terminal 61 and a portion of the second terminal 62 are sandwiched between the first case 6a and the second case 6b, and are fixed in place by the cover 4. As shown in Figures 1 to 3, the first case 6a and the second case 6b have the same shape and are approximately semi-cylindrical. In this embodiment, since the first case 6a and the second case 6b have the same shape, they are preferably manufactured using the same material, which reduces the number of types of parts to be manufactured. The first case 6a and the second case 6b may also be made of different materials.

[0071] In this embodiment, the first case 6a and the second case 6b have the same shape and are arranged opposite each other with the fuse element 2 interposed therebetween, so that the stress caused by the pressure increase inside the accommodating portion 60 when the fuse element 2 melts is evenly distributed and applied to the first case 6a and the second case 6b. Therefore, the case 6 has excellent strength and can effectively prevent damage to the protection element 100 when the fuse element 2 melts.

[0072] As shown in Figures 1 to 3, a storage section 60 is provided inside the case 6. The storage section 60 is formed by integrating a first case 6a and a second case 6b. The storage section 60 accommodates the fuse element 2, the first shielding member 3a, and the second shielding member 3b.

[0073] 3, two insertion holes 64 that open into the storage section 60 are arranged opposite each other in the X direction within the storage section 60. The two insertion holes 64 are formed by integrating the second case 6b and the first case 6a. As shown in FIG. 3, one of the two insertion holes 64 accommodates the first end 21 of the fuse element 2, and the other insertion hole 64 accommodates the second end 22 of the fuse element 2. As shown in FIGS. 1 and 3, a portion of the first terminal 61 and a portion of the second terminal 62 connected to the fuse element 2 are exposed to the outside of the case 6.

[0074] In this embodiment, the structure of the first case 6a will be described with reference to Figures 10 and 11. The structure of the second case 6b is the same as that of the first case 6a, and therefore description thereof will be omitted. Fig. 10 is a diagram illustrating the structure of the first case 6a provided in the protection element 100 of the first embodiment. Fig. 10(a) is a perspective view seen from the outside, and Figs. 10(b) and 10(c) are perspective views seen from the housing section side. Fig. 11 is a diagram illustrating the structure of the first case 6a provided in the protection element 100 of the first embodiment. Fig. 11(a) is a plan view seen from the housing section side, Fig. 11(b) is a plan view seen from the outside, and Figs. 11(c) to (e) are side views.

[0075] As shown in Figures 10(b), 10(c), and 11(a), the first case 6a is a roughly rectangular shape in plan view with its longer side in the X direction and its shorter side in the Y direction, with the length in the Y direction being shorter at the center in the X direction. As shown in Figures 10(b), 10(c), and 11(a), in the first case 6a, the area that becomes the inner surface of the accommodating section 60 by being integrated with the second case 6b is provided with a recess 68, a shielding member accommodating groove 34, and a fuse element mounting surface 65.

[0076] As shown in Figures 10(b), 10(c), and 11(a), the recess 68 is generally rectangular in plan view. As shown in Figure 4, the recess 68 accommodates the first shielding member 3a (or the second shielding member 3b in the case of the second case 6b). In this embodiment, as shown in Figures 4, 10(c), and 11(a), of the inner wall surfaces of the recess 68, a first wall surface 68a disposed on the inside of the first case 6a in the X direction is disposed at approximately the center of the first case 6a in the X direction. Therefore, the first wall surface 68a is disposed so as to overlap the cutting portion 23 of the fuse element 2 in the Z direction (see Figure 4).

[0077] As shown in FIG. 4, the bottom surface of the recess 68 is the surface facing the second surface 32 of the plate-shaped portion 30 of the first shielding member 3a (or the second shielding member 3b in the case of the second case 6b). As shown in FIGS. 10(b), 10(c), and 11(a), the bottom surface of the recess 68 has a first bottom surface 68c disposed on the first wall surface 68a side and a second bottom surface 68d disposed on the second wall surface 68b side facing the first wall surface 68a. The first bottom surface 68c is located closer to the surface facing the fuse element 2 in the Z direction than the second bottom surface 68d. As a result, as shown in FIGS. 4 and 10(c), a step extending in the Y direction is formed at the boundary between the first bottom surface 68c and the second bottom surface 68d. In this embodiment, as shown in Figures 4 and 10(c), the step formed in the recess 68 of the first case 6a functions as the rotation axis 33 of the first shielding member 3a (in the case of the second case 6b, the rotation axis 33 of the second shielding member 3b).

[0078] 4 and 10(c), the position in the X direction of the step (rotation axis 33) formed in the recess 68 of the first case 6a is closer to the first wall surface 68a than to the second wall surface 68b. As a result, as shown in Fig. 9(a), of the area of ​​the plate-shaped portion 30 of the first shielding member 3a (second shielding member 3b in the case of the second case 6b) as seen from the fuse element 2, a first area 30a arranged on the first end side 31a side closer to the rotation axis 33 than a contact position 33a between the plate-shaped portion 30 and the rotation axis 33 is smaller than a second area 30b arranged on the second end side 31b side farther from the rotation axis 33. In this embodiment, the ratio of the X-direction length of the first bottom surface 68c to the X-direction length of the recess 68 (first bottom surface 68c / X-direction length of recess 68) is approximately the same as the ratio of the area of ​​the plate-shaped portion 30 to the first area 30a (first area 30a / area of ​​plate-shaped portion 30), and is less than 0.5, preferably 0.2 to 0.49, and more preferably 0.3 to 0.4.

[0079] When the ratio of the X-direction length of the first bottom surface 68c to the X-direction length of the recess 68 is 0.4 or less, the difference between the first area 30a and the second area 30b becomes sufficiently large. As a result, the pressing force of the first shielding member 3a against the first surface 31 of the plate-like portion 30 due to a pressure increase in the accommodating portion 60 also becomes significantly different between the second end edge 31b side and the first end edge 31a side. Therefore, the pressing force due to the pressure increase in the accommodating portion 60 is efficiently converted into a driving force that rotates the first shielding member 3a. As a result, as shown in FIG. 6 , the first shielding member 3a rotates at a sufficient rotational speed in a direction in which the second end edge 31b side, located on the outer side of the accommodating portion 60 in the X direction, moves away from the fuse element 2, and in a direction in which the first end edge 31a side, located on the inner side of the accommodating portion 60 in the X direction, moves toward the fuse element 2. Then, the first end edge 31a is pressed with a strong force onto the bottom surface of the shielding member accommodating groove 34 provided on the inner surface of the accommodating portion 60. For this reason, when the ratio of the X-direction length of the first bottom surface 68c to the X-direction length of the recess 68 is 0.4 or less, the inside of the accommodating portion 60 is more reliably blocked and divided by the first end edge 31a of the first surface 31 of the plate-shaped portion 30, the portion of the second surface 32 that is in contact with the rotation shaft 33, and the side surface of the plate-shaped portion 30.

[0080] When the ratio of the X-direction length of the first bottom surface 68c to the X-direction length of the recess 68 is 0.3 or more, a sufficient area of ​​the first bottom surface 68c can be ensured. Therefore, the first bottom surface 68c can more stably hold the first shielding member 3a in a predetermined position within the first case 6a before rotational movement. As a result, the protection element 100 has better reliability.

[0081] In the present embodiment, the first bottom surface 68c is disposed on the first wall surface 68a side of the recess 68, and the second bottom surface 68d is disposed on the second wall surface 68b side. However, the second bottom surface 68d may be disposed on the first wall surface 68a side of the recess 68, and the first bottom surface 68c may be disposed on the second wall surface 68b side. In this case, the X-direction position of the step (rotation axis 33) formed in the recess 68 of the first case 6a is closer to the second wall surface 68b than to the first wall surface 68a. Therefore, of the X-direction ends of the first surface 31 of the plate-like portion 30 of the first shielding member 3a, the first end edge 31a closer to the rotation axis 33 is disposed on the outer side of the accommodation portion 60 in the X-direction, and the second end edge 31b farther from the rotation axis 33 is disposed on the inner side of the accommodation portion 60 in the X-direction. The rotation direction of the first shielding member 3a is opposite to that of the protection element 100 of this embodiment.

[0082] In this embodiment, the first bottom surface 68c is disposed on the first wall surface 68a side of the recess 68, and the second bottom surface 68d is disposed on the second wall surface 68b side. Therefore, compared to a case where the second bottom surface 68d is disposed on the first wall surface 68a side and the first bottom surface 68c is disposed on the second wall surface 68b side, the position in the X direction blocked by the first shielding member 3a and the position in the X direction blocked by the second shielding member 3b are closer to each other and are closer to the cutting portion 23 (heat spot) within the accommodating portion 60. This makes it easier for the arc discharge generated when the fuse element 2 melts to be smaller, which is preferable.

[0083] In this embodiment, the length of the recess 68 in the Y direction is preferably such that the plate-shaped portion 30 of the first shielding member 3a fits into the recess 68 while contacting the inner wall surface of the recess 68. In this case, the first shielding member 3a can rotate due to the increase in pressure inside the accommodating portion 60 when the fuse element 2 blows. Furthermore, as the first shielding member 3a rotates, the inside of the accommodating portion 60 is more reliably blocked and divided by the first end edge 31a of the first surface 31 of the plate-shaped portion 30, the portion of the second surface 32 that contacts the rotation axis 33, and the side surface of the plate-shaped portion 30. Furthermore, the first shielding member 3a can be more stably held in a predetermined position inside the first case 6a before rotation. Specifically, the distance between the inner wall surfaces of the recess 68 facing each other in the Y direction and the plate-shaped portion 30 is preferably 0.05 to 0.2 mm, and more preferably 0.05 to 0.1 mm.

[0084] 11(a), one guide hole 66 and two bottom vent holes 69 are provided in the second bottom surface 68d of the recess 68. As shown in FIGS. 11(a) and 11(b), the one guide hole 66 and the two bottom vent holes 69 penetrate the first case 6a in the Z direction and open to the second bottom surface 68d and the outer surface of the first case 6a.

[0085] The guide hole 66 discharges gas generated in the accommodating portion 60 by arc discharge into the internal pressure buffering space 71 when the fuse element 2 melts. The guide hole 66, together with the protrusion 38 of the first shielding member 3a, also functions as a guide for rotating the first shielding member 3a to a predetermined position when the fuse element 2 melts. The guide hole 66 is sized so that it can accommodate the protrusion 38 of the first shielding member 3a when the first shielding member 3a rotates.

[0086] The guide hole 66 is generally rectangular in plan view. The inner wall surface of the guide hole 66 on the outer side in the X direction is positioned further outward in the X direction than the second wall surface 68b, as shown in FIGS. 4, 10(b), and 11(b). As shown in FIGS. 4 and 10(b), the inner wall surface of the guide hole 66 extends to a position closer to the surface facing the fuse element 2 than the second bottom surface 68d. Therefore, even if the first shielding member 3a rotates and the protrusion 38 is accommodated in the guide hole 66 when the fuse element 2 blows, the guide hole 66 is not blocked by the shielding member 3a. Therefore, gas generated in the accommodation portion 60 by arc discharge can be reliably discharged to the internal pressure buffering space 71. Furthermore, as shown in FIG. 6, the rotation of the first shielding member 3a facilitates the second end edge 31b of the first surface 31 of the plate-like portion 30 being accommodated in the recess 68 along the inner wall surface of the guide hole 66. Furthermore, since the first case 6a has the second wall surface 68b, the first case 6a can hold the first shielding member 3a, before it rotates, in a predetermined position along the second wall surface 68b with high precision and even more stability.

[0087] The bottom vent hole 69 is substantially cylindrical in shape and prevents a pressure rise in the recess 68 when the fuse element 2 melts, thereby preventing arc discharge. In this embodiment, an example has been described in which a substantially cylindrical bottom vent hole 69 is provided, but the shape of the vent hole is not limited to a substantially cylindrical shape, and may be, for example, an elongated cylindrical shape, an elliptical cylindrical shape, a polygonal cylindrical shape, etc. 11(a), the two bottom vent holes 69 are disposed symmetrically with respect to the center in the Y direction. This is preferable because when the fuse element 2 melts, the gas inside the housing portion 60 is easily and uniformly discharged to the outside of the housing portion 60 via the two bottom vent holes 69.

[0088] In this embodiment, an example has been described in which two bottom vent holes 69 are provided, but the number of bottom vent holes is not particularly limited, and may be one, or three or more, or there may be no bottom vent hole 69. When no bottom vent hole 69 is provided, it is preferable to have guide holes 66 and / or side vent holes 77, which will be described later.

[0089] As shown in FIGS. 3, 10(b), 10(c), and 11(a), a shielding member accommodating groove 34 is provided on the surface of the first case 6a facing the accommodating portion 60, opposite the recess 68 in plan view with respect to the approximate center in the X direction. The shielding member accommodating groove 34 is generally rectangular in plan view and is a groove with a flat bottom. As shown in FIGS. 5 and 6, a portion of the plate-shaped portion 30 is accommodated in the shielding member accommodating groove 34 when the first shielding member 3a rotates. In this embodiment, the length of the shielding member accommodating groove 34 in the Y direction is longer than the length of the first shielding member 3a in the Y direction. Therefore, when the first shielding member 3a rotates, the entire first end edge 31a of the first surface 31 of the plate-shaped portion 30 is positioned in contact with the bottom surface of the shielding member accommodating groove 34.

[0090] 10(b), 10(c), and 11(a), the outer sides of the edges of the shielding member accommodating groove 34 facing in the Y direction are made into joining surfaces 70 that are joined to the second case 6b. Therefore, when the first shielding member 3a rotates with the first case 6a and the second case 6b joined together, the inside of the accommodating section 60 is more reliably blocked and divided by the first end edge 31a of the first surface 31 of the plate-shaped portion 30, the portion of the second surface 32 that is in contact with the rotation axis 33, and the side surface of the plate-shaped portion 30.

[0091] The depth of the shielding member accommodating groove 34 is preferably 0.5 to 2 times, and more preferably 0.5 to 1 time, the thickness of the fuse element 2. When the depth of the shielding member accommodating groove 34 is 0.5 times or more the thickness of the fuse element 2, the inside of the accommodating section 60 can be divided more reliably by the rotation of the first shielding member 3a. Furthermore, when the depth of the shielding member accommodating groove 34 is equal to or less than twice the thickness of the fuse element 2, the shielding member accommodating groove 34 functions as a stopper, thereby ensuring an appropriate range of rotational movement of the first shielding member 3a. Therefore, the size of the recess 68 does not need to be excessively large to avoid contact between the first shielding member 3a and the recess 68 due to the rotational movement of the first shielding member 3a, and this does not hinder the miniaturization of the protection device 100.

[0092] Furthermore, in order to effectively suppress the continuation of arc discharge that occurs when the fuse element 2 is cut, it is preferable that the distance in the Z direction between the surface of the fuse element 2 and the inner wall of the accommodating portion 60 is short. As shown in Fig. 4, the distance in the Z direction between the surface of the fuse element 2 and the bottom surface of the fuse element mounting surface 65 is shorter than the distance in the Z direction between the surface of the fuse element 2 and the bottom surface of the shielding member accommodating groove 34. Therefore, it is preferable to shorten the length in the X direction of the shielding member accommodating groove 34 so that the area of ​​the surface of the fuse element 2 that faces the fuse element mounting surface 65 is increased.

[0093] When the depth of the shielding member accommodating groove 34 is no more than twice the thickness of the fuse element 2, even if the length of the shielding member accommodating groove 34 in the X direction is short, the first end edge 31a of the first surface 31 of the plate-shaped portion 30 can be placed in contact with the bottom surface of the shielding member accommodating groove 34 without excessive rotational movement of the first shielding member 3a. Therefore, the proportion of the area of ​​the surface of the fuse element 2 that faces the fuse element mounting surface 65 can be increased, and arc discharge that occurs when the fuse element 2 is cut can be suppressed.

[0094] 10(b), 10(c), and 11(a), on the surface of the first case 6a facing the accommodating section 60, a fuse element mounting surface 65 consisting of a recess is provided on the outer side in the X direction of the shielding member accommodating groove 34 in a plan view. Steps are formed at the boundary between the fuse element mounting surface 65 and the shielding member accommodating groove 34, and at the boundary between the fuse element mounting surface 65 and a joining surface 70 that is joined to the second case 6b. In this embodiment, the depth of the recess that forms the fuse element mounting surface 65 is preferably equal to or less than the thickness of the fuse element 2, and can be, for example, half the thickness of the fuse element 2.

[0095] The bottom surface of the fuse element mounting surface 65 is disposed in close proximity to or in contact with the fuse element 2, and is preferably disposed in contact with the fuse element 2 as shown in Fig. 4. When the bottom surface of the fuse element mounting surface 65 and the fuse element 2 are disposed in contact with each other, the arc discharge that occurs when the fuse element 2 melts becomes even smaller in scale.

[0096] In this embodiment, the distance in the Z direction between the bottom surface of the fuse element mounting surface 65 of the first case 6a (second case 6b) and the second shielding member 3b (first shielding member 3a) disposed opposite the fuse element 2 is preferably 10 times or less, more preferably 5 times or less, and even more preferably 2 times or less, the thickness of the fuse element 2. It is particularly preferable that the fuse element 2 is in contact with the bottom surface of the fuse element mounting surface 65 of the first case 6a (second case 6b) and / or the second shielding member 3b (first shielding member 3a). When the distance in the Z direction is 10 times or less the thickness of the fuse element 2, the number of electric field lines generated by arc discharge is reduced, and the arc discharge generated when the fuse element 2 melts is small. Furthermore, because the distance in the Z direction is short, the protection device 100 can be made smaller.

[0097] 10(b), 10(c), and 11(a), a leak prevention groove 35 extending in the Y direction is provided on the bottom surface of the fuse element mounting surface 65 at a position on the outside in the X direction. When the molten fuse element 2 is blown and the molten fuse element 2 scatters and the scattered material adheres to the inside of the housing portion 60, the leak prevention groove 35 cuts off the electrical path formed by the scattered material, thereby preventing leakage current.

[0098] The length in the Y direction of the leak prevention groove 35 is preferably longer than the Y direction width 21D at the first end 21 and the Y direction width 22D at the second end 22 of the fuse element 2. In this case, it is possible to more effectively prevent the scattered matter that has adhered to the inside of the accommodating portion 60 when the fuse element 2 melts from being electrically connected to the first terminal 61 or the second terminal 62, thereby more effectively preventing the occurrence of leak current. The leak prevention groove 35 is formed with a substantially constant width and depth. The width and depth of the leak prevention groove 35 are not particularly limited as long as the leak prevention groove 35 can cut off the electrical path formed by the deposits scattered when the fuse element 2 melts, thereby preventing the leakage current.

[0099] The protection element 100 of this embodiment preferably has a leak prevention groove 35, but may not have the leak prevention groove 35. Furthermore, the leak prevention groove 35 is preferably provided on the bottom surface of the fuse element mounting surface 65 at a position on the outside in the X direction, extending in the Y direction, but may be provided at another position on the bottom surface of the fuse element mounting surface 65, or may not extend in the Y direction.

[0100] 10(a) to 10(c) and 11(a), side recesses 77a each made of a recess are provided on the edge of recess 68 facing in the Y direction and within the range in which second bottom surface 68d is formed in the X direction. As shown in FIGS. 10(b) and 10(c), a step is formed at the boundary between side recesses 77a arranged on the edge of recess 68 and joining surface 70 that is joined to second case 6b.

[0101] 10(a) to 10(c) and 11(a), side recesses 77a each consisting of a flat surface continuing from the bottom surface of the fuse element mounting surface 65 are provided on the edge portions of the fuse element mounting surface 65 facing in the Y direction and located closer to the center in the X direction than the leak prevention groove 35. As shown in FIGS. 10(b) and 10(c), a step is formed at the boundary between the side recesses 77a arranged on the edge portions of the fuse element mounting surface 65 and the joining surface 70 that is joined to the second case 6b.

[0102] The four side recesses 77a provided on the edge of the recess 68 of the first case 6a are integrated with the second case 6b, and together with the four side recesses 77a provided in the second case 6b, form four side vents 77 that penetrate the case 6 (see FIG. 1). The side vents 77 suppress a pressure increase inside the accommodating section 60 when the fuse element 2 melts, thereby suppressing arc discharge.

[0103] In this embodiment, the two side recesses 77a arranged on the edge of the recess 68 and the two side recesses 77a arranged on the edge of the fuse element mounting surface 65 each have a depth that is half the thickness of the fuse element 2. The two side recesses 77a arranged on the edge of the recess 68 and the two side recesses 77a arranged on the edge of the fuse element mounting surface 65 have the same shape and are arranged symmetrically with respect to the center of the accommodating section 60 in the X direction. Therefore, the four side vents 77 formed by integrating the first case 6a and the second case 6b are preferably positioned so that gas generated inside the accommodating section 60 when the fuse element 2 melts can be easily and uniformly discharged to the outside of the accommodating section 60.

[0104] In the present embodiment, the depth of the side surface recess 77a is described as half the thickness of the fuse element 2, but the depth of the side surface recess 77a is not particularly limited. In addition, in the present embodiment, the four side surface recesses 77a have the same shape, but some or all of the four side surface recesses 77a may have different shapes.

[0105] In this embodiment, an example has been described in which four side vents 77 are provided, but the number of side vents is not particularly limited, and may be three or less, five or more, or no side vents may be provided. When no side vents 77 are provided, it is preferable to have guide holes 66 and / or bottom vents 69.

[0106] 10(b), 10(c), and 11(a), on the surface of the first case 6a facing the accommodating section 60, insertion hole forming surfaces 64a each consisting of a recess are provided on the outer side in the X direction of the recess 68 and the fuse element mounting surface 65 in a plan view. A step is formed at the boundary between each insertion hole forming surface 64a and a joining surface 70 joined to the second case 6b. The step between the insertion hole forming surface 64a and the joining surface 70 is sized so that, when the first case 6a and the second case 6b are integrated, an insertion hole 64 capable of accommodating the stacked portion of the first terminal 61 (or the second terminal 62) and the fuse element 2 can be formed.

[0107] The length in the Y direction of the insertion hole forming surface 64a is longer than the Y direction width 21D of the first end 21 and the Y direction width 22D of the second end 22 of the fuse element 2. Therefore, the entire surfaces of the first end 21 and the second end 22 of the fuse element 2 in the widths 21D and 22D directions are arranged on the insertion hole forming surface 64a.

[0108] As shown in Figures 10(b), 10(c), and 11(a), terminal mounting surfaces 64b each having a recess are provided so as to surround the outer sides of the two insertion hole forming surfaces 64a in the X direction and a portion of the outer side of the insertion hole forming surfaces 64a in the Y direction in a plan view. The terminal mounting surfaces 64b have an outer shape corresponding to the planar shapes of the first terminals 61 and the second terminals 62. This allows the first case 6a to be easily aligned with the first terminals 61 and the second terminals 62. Furthermore, the first terminals 61 and the second terminals 62 are less likely to come off the case 6a.

[0109] 10(b) and 10(c), the terminal mounting surface 64b is located closer in the Z direction to the joining surface 70 that is joined to the second case 6b than the surface of the insertion hole forming surface 64a. As a result, a step is formed at the boundary between the terminal mounting surface 64b and the insertion hole forming surface 64a. A step is also formed at the boundary between the terminal mounting surface 64b and the joining surface 70 that is joined to the second case 6b. The step between the terminal mounting surface 64b and the joining surface 70 is sized to accommodate the first terminal 61 (or the second terminal 62) when the first case 6a and the second case 6b are integrated.

[0110] 10(b), 10(c), and 11(a), notches 78a each consisting of a recess with a substantially semicircular bottom surface are formed in the center in the Y direction on the outer edge of each of the two terminal mounting surfaces 64b in the X direction. When the first case 6a and the second case 6b are integrated, each of the notches 78a becomes a first adhesive injection port 78 (see FIGS. 1 and 3) that has a substantially cylindrical shape when viewed from the X direction.

[0111] 10(a) to 10(c) and 11(a) to 11(d), notches 76a are formed at the four corners of the first case 6a in plan view on the joining surface 70 where the first case 6a is joined to the second case 6b. When the first case 6a and the second case 6b are integrated, the notches 76a become hollow second adhesive injection ports 76 (see FIG. 1) that have a semicircular columnar cross-section when viewed from the X direction.

[0112] As shown in Figures 10(b) and 10(c), of the four notches 76a formed on the joining surface 70 where the first case 6a is joined to the second case 6b, two notches 76a formed on the recess 68 side are formed between the terminal mounting surface 64b and each of the two notches 76a, which are approximately circular in plan view. 10(b), 10(c), and 11(a), of the four notches 76a formed in the joining surface 70 of the first case 6a that joins with the second case 6b, two notches 76a formed on the fuse element mounting surface 65 side are formed between the terminal mounting surface 64b and each of the four notches 76a, and a mating protrusion 67 that is generally circular in plan view is formed between each of the two notches 76a and the terminal mounting surface 64b. Each of the mating recesses 63 is fitted with each of the mating protrusions 67 when the first case 6a and the second case 6b are integrated together.

[0113] As shown in FIGS. 10(a), 11(b), and 11(e), the outer surface of the first case 6a is provided with a first buffer recess 73 formed on the surface opposite the joining surface 70 where the second case 6b is joined. Also, as shown in FIGS. 10(a) to 10(c) and 11(a), second recesses 74 are provided on both side surfaces of the first case 6a in the Y direction. The second recesses 74 are formed into second buffer recesses 75 (see FIG. 1) when the first case 6a and the second case 6b are integrated together. Also, as shown in FIGS. 10(a) to 10(c) and 11(b) to 11(e), end members 72 having a semi-cylindrical outer shape are provided on both ends of the outer surface of the first case 6a in the X direction. The end members 72 are formed into a cylindrical shape when the first case 6a and the second case 6b are integrated together.

[0114] The first buffering recess 73 and the second recess 74 (second buffering recess 75) form an internal pressure buffering space 71 surrounded by the outer surface of the case 6 formed by integrating the first case 6a and the second case 6b and the inner surface of the cover 4. The internal pressure buffering space 71 is provided in a circular ring shape along the inner surface of the cover 4 at the center of the cover 4 in the X direction. In this embodiment, the length (thickness) of the end member 72 in the X direction is sufficiently ensured so that it can withstand stress caused by a pressure increase in the internal pressure buffering space 71 when the fuse element 2 is blown. Specifically, the length of the end member 72 in the X direction is preferably set to, for example, 1 to 3 times the thickness of the cover 4.

[0115] 11(a) and 11(b), a guide hole 66 and two bottom vent holes 69 that penetrate the first case 6a and communicate between the storage section 60 and the internal pressure buffering space 71 are open in the first buffering recess 73. Furthermore, as shown in FIG. 1, two second buffering recesses 75 formed by integrating the first case 6a and the second case 6b are each formed by integrating a side recess 77a provided in the first case 6a with a side recess 77a provided in the second case 6b, and each penetrate the case 6 to communicate between the storage section 60 and the internal pressure buffering space 71.

[0116] Gas generated in the accommodating portion 60 when the fuse element 2 melts flows into the internal pressure buffering space 71 from inside the accommodating portion 60 via the side vent 77, the guide hole 66, and the bottom vent 69. This suppresses the pressure increase in the accommodating portion 60 when the fuse element 2 melts, and suppresses arc discharge. The volume of the internal pressure buffering space 71 is preferably equal to or larger than the volume of the fuse element 2, more preferably equal to or larger than 100 times the volume of the fuse element 2, and even more preferably equal to or larger than 1000 times the volume of the fuse element 2, in order to effectively suppress the pressure increase in the accommodating portion 60.

[0117] The first case 6a and the second case 6b are made of an insulating material. The insulating material may be the same as that used for the first shielding member 3a and the second shielding member 3b. The first case 6a and the second case 6b may be made of the same material as the first shielding member 3a and the second shielding member 3b, or may be made of different materials. The first case 6a and the second case 6b can be manufactured by a known method.

[0118] (cover) 1, the cover 4 covers the side surface of the case 6 along the X direction and fixes the first case 6a and the second case 6b together. As shown in FIGS. 1 and 3, the cover 4 exposes a portion of the first terminal 61 from the first end 41 and a portion of the second terminal 62 from the second end 42. As shown in Fig. 2, the cover 4 has a cylindrical shape with a substantially uniform thickness, and has an inner diameter corresponding to the substantially cylindrical shape formed by integrating the end member 72 of the first case 6a and the end member 72 of the second case 6b, as shown in Fig. 3. As shown in Figs. 2 and 3, the inner edge of the opening of the cover 4 is formed as a chamfered inclined surface 4a. In this embodiment, the spatial region consisting of the storage section 60 and the internal pressure buffer space 71 is sealed by the outer surface of the case 6 and the inner surface of the cover 4 .

[0119] In this embodiment, the cover 4 is cylindrical. Therefore, the pressure on the cover 4 when the fuse element 2 melts is distributed approximately evenly across the entire inner surface of the cover 4 via an internal pressure buffering space 71, which is annularly formed along the inner surface of the cover 4 at the center of the cover 4 in the X direction, and an end member 72, which is housed along the inner surface of the cover 4 at the edge of the cover 4 in the X direction. As a result, the cover 4 exhibits excellent strength and effectively prevents damage to the protection element 100 when the fuse element 2 melts. Furthermore, because the cover 4 is cylindrical, it can be easily manufactured, resulting in excellent productivity.

[0120] The cover 4 is made of an insulating material. The insulating material can be the same as that used for the first shielding member 3a and the second shielding member 3b, and the first case 6a and the second case 6b. The cover 4, the first case 6a and the second case 6b, and the first shielding member 3a and the second shielding member 3b may all be made of different materials, or some or all of them may be made of the same material. The cover 4 can be manufactured by a known method.

[0121] (Protection element manufacturing method) Next, a method for manufacturing the protection element 100 of this embodiment will be described. To manufacture the protection element 100 of this embodiment, first, the fuse element 2, the first terminal 61, and the second terminal 62 are prepared. Then, as shown in Fig. 7, the first terminal 61 is connected to the first end 21 of the fuse element 2 by soldering. Also, the second terminal 62 is connected to the second end 22 by soldering.

[0122] As the solder material used for soldering in this embodiment, known materials can be used, and it is preferable to use a material containing Sn as the main component from the viewpoints of resistivity, melting point, and environmental friendliness and lead-freeness. The first end 21 and the second end 22 of the fuse element 2, and the first terminal 61 and the second terminal 62 may be connected by welding, and any known joining method can be used.

[0123] Next, the first shielding member 3a and the second shielding member 3b shown in FIGS. 8 and 9, and the first case 6a and the second case 6b shown in FIGS. 10 and 11 are prepared. Then, the first shielding member 3a is placed in the recess 68 of the first case 6a. At this time, as shown in FIG. 4, the second surface 32 of the plate-shaped portion 30 of the first shielding member 3a is placed in contact with a step (rotation axis 33) formed in the recess 68 of the first case 6a. Also, the second shielding member 3b is placed in the recess 68 of the second case 6b. At this time, as shown in FIG. 4, the second surface 32 of the plate-shaped portion 30 of the second shielding member 3b is placed in contact with a step (rotation axis 33) formed in the recess 68 of the second case 6b. FIG. 12(a) is a perspective view of the second case 6b with the second shielding member 3b placed therein, as seen from the side that becomes the storage section 60.

[0124] 12(b), a member in which the fuse element 2, the first terminal 61, and the second terminal 62 are integrated is placed on the second case 6b on which the second shielding member 3b is placed. In this embodiment, the fuse element 2, the first terminal 61, and the second terminal 62 are aligned with the second case 6b by placing the first terminal 61 and the second terminal 62 on the two terminal placement surfaces 64b, respectively.

[0125] In this embodiment, as shown in Figure 12(b), an example will be described in which the surfaces of the first terminal 61 and the second terminal 62 at the connection portion between the first end 21 and the second end 22 of the fuse element 2 facing the first terminal 61 and the second terminal 62 are installed facing the second case 6b, but the surface facing the fuse element 2 may also be installed facing the second case 6b.

[0126] Next, the first case 6a with the first shielding member 3a installed is placed on the second case 6b with the fuse element 2, the first terminal 61, and the second terminal 62 integrated together, and the second shielding member 3b installed. At this time, the mating recess 63 of the first case 6a is fitted into the mating protrusion 67 of the second case 6b, and the mating protrusion 67 of the first case 6a is fitted into the mating recess 63 of the second case 6b. This aligns the first case 6a and the second case 6b. FIG. 13(a) is a perspective view showing the state in which the first case 6a is installed on the second case 6b with the fuse element 2 interposed therebetween.

[0127] 13(a), by placing the first case 6a on the second case 6b, a second buffer recess 75, a side vent 77, a first adhesive injection port 78, and a second adhesive injection port 76 are formed. Also, as shown in FIG. 3, the first end 21 of the fuse element 2 is accommodated in one insertion hole 64, and the second end 22 of the fuse element 2 is accommodated in the other insertion hole 64, so that parts of the first terminal 61 and the second terminal 62 connected to the fuse element 2 are exposed to the outside of the case 6.

[0128] 13(b), the first case 6a and the second case 6b are housed in an integrated state in the cover 4. As a result, the end member 72, the first buffering recess 73, and the second buffering recess 75, which form the side surface of the case 6 along the X direction, are covered by the cover 4, and the first case 6a and the second case 6b are fixed together. Thereafter, adhesive is injected into the inclined surface 4a of the cover 4, the first adhesive injection port 78, and the second adhesive injection port 76. For example, an adhesive containing a thermosetting resin can be used as the adhesive. This seals the inside of the cover 4, and as shown in FIGS. 1 and 3, the spatial region consisting of the housing section 60 and the internal pressure buffering space 71 is sealed by the outer surface of the case 6 and the inner surface of the cover 4. Through the above steps, the protective element 100 of this embodiment is obtained.

[0129] (Protection element operation) Next, the operation of the protection device 100 of this embodiment when a current exceeding the rated current flows through the fuse element 2 of the protection device 100 will be described. When a current exceeding the rated current flows through the fuse element 2 of the protection device 100 of this embodiment, the fuse element 2 heats up due to the overcurrent, causing the temperature of the fuse element 2. When the temperature rises, the cutting portion 23 of the fuse element 2 melts and is blown or cut off. At this time, a spark occurs between the cut surfaces or melted surfaces of the cutting portion 23, causing an arc discharge.

[0130] In the protection element 100 of this embodiment, of the areas of the plate-shaped portions 30 of the first shielding member 3a and the second shielding member 3b as viewed from the fuse element 2, the first area 30a arranged on the first end side 31a side closer to the rotation axis 33 is smaller than the second area 30b arranged on the second end side 31b side farther from the rotation axis 33. Therefore, when the first surfaces 31 of the plate-shaped portions 30 of the first shielding member 3a and the second shielding member 3b are pressed by a pressure increase inside the accommodating portion 60 due to an arc discharge that occurs when the fuse element 2 melts, the first shielding member 3a rotates about the rotation axis 33, and the second shielding member 3b also rotates about the rotation axis 33, as shown in Figures 5 and 6.

[0131] 6 , the first shielding member 3a and the second shielding member 3b rotate such that the second end edge 31b located on the outer side of the accommodating portion 60 in the X direction moves away from the fuse element 2, and the first end edge 31a located on the inner side of the accommodating portion 60 in the X direction moves toward the fuse element 2. The first end edge 31a is pressed against the bottom surface of the shielding member accommodating groove 34 provided on the inner surface of the accommodating portion 60. The second end edge 31b is accommodated in the recess 68.

[0132] As described above, the protection element 100 of this embodiment includes the fuse element 2 that is energized in the X direction, the first shielding member 3a and the second shielding member 3b that are made of an insulating material and have a plate-like portion 30 with a first surface 31 facing the fuse element 2 and a second surface 32 that is in contact with the rotation axis 33 extending in the Y direction, and the area of ​​the plate-like portion 30 as seen from the fuse element 2 is divided into a first area 30a and a second area 30b that are different from each other by a contact position 33a between the plate-like portion 30 and the rotation axis 33, and the case 6 that is made of an insulating material and has an accommodation section 60 inside that accommodates the fuse element 2, the first shielding member 3a, and the second shielding member 3b.

[0133] In the protection device 100 of this embodiment, the pressure inside the accommodating portion 60 increases due to an arc discharge that occurs when the fuse element 2 melts, and this presses the first surfaces 31 of the first shielding member 3a and the second shielding member 3b. This causes the first shielding member 3a and the second shielding member 3b to rotate about the rotation axis 33, as shown in Figures 5 and 6. As a result, the inside of the accommodating portion 60 is blocked and divided at two locations in the X direction by the first shielding member 3a and the second shielding member 3b.

[0134] At this time, in this embodiment, a space is formed between the first shielding member 3a and the second shielding member 3b. This space is surrounded by the bottom surface of the shielding member accommodating groove 34, the recess 68, the first end side 31a of the first surface 31 of the plate-like portion 30 of each of the first shielding member 3a and the second shielding member 3b, the portion of the second surface 32 that contacts the rotation shaft 33, and the side surface of the plate-like portion 30.

[0135] Therefore, in this embodiment, the inside of the accommodating portion 60 is divided by the first shielding member 3a and the second shielding member 3b, so that the melting surfaces or cut surfaces of the cut or melted fuse element 2 are insulated from each other, and the two insertion holes 64 opening into the accommodating portion 60 are separated from each other, cutting off the current path. As a result, the arc discharge that occurs when the fuse element 2 melts is quickly extinguished (extinguished).

[0136] That is, in the protective element 100 of this embodiment, the arc discharge that occurs when the fuse element 2 melts is small. Therefore, the protective element 100 of this embodiment can prevent the accommodating portion 60 from being destroyed by a pressure increase inside the accommodating portion 60, and is therefore excellent in safety. The protection element 100 of this embodiment can be preferably installed in a current path with a high voltage of 100V or more and a large current of 100A or more, and can also be installed in a current path with a high voltage of 400V or more and a large current of 120A or more.

[0137] The protection element 100 of this embodiment includes a case 6 made of an insulating material and housing the fuse element 2, exposing portions of the first terminal 61 and the second terminal 62 electrically connected to the fuse element 2, which is energized in the X direction, and a cylindrical cover 4 made of an insulating material and covering the side surface of the case 6 along the X direction, exposing a portion of the first terminal 61 at the first end 41 and a portion of the second terminal 62 at the second end 42. Therefore, in the protection element 100 of this embodiment, stress caused by a pressure increase within the case 6 when the fuse element 2 melts is applied to the case 6 and the cover 4 covering the side surface of the case 6 along the X direction. This provides superior strength against a pressure increase within the case 6 compared to, for example, a case without the cover 4. Therefore, the protection element 100 of this embodiment is less likely to break when the fuse element 2 melts and has excellent safety.

[0138] In the protection device 100 of this embodiment, it is more preferable that the fuse element 2 is made of a laminate in which an inner layer made of Sn or a metal mainly containing Sn and an outer layer made of Ag or Cu or a metal mainly containing Ag or Cu are laminated in the thickness direction, and that the shielding member 3, case 6, and cover 4 are made of a resin material. In such a protection device, for the reasons described below, the arc discharge that occurs when the fuse element 2 melts is further reduced in scale, and further miniaturization is possible.

[0139] That is, when the fuse element 2 is made of the laminate, the fuse element 2 has a low melting temperature of, for example, 300 to 400°C. Therefore, sufficient heat resistance can be obtained even if the shielding member 3, the case 6, and the cover 4 are made of a resin material. Furthermore, because the melting temperature of the fuse element 2 is low, even if the inner surface of the shielding member 3 and / or the accommodating portion 60 is placed in contact with the cutting portion 23 of the fuse element 2, the fuse element 2 reaches its melting temperature in a short time. Therefore, the distance in the Z direction between the fuse element 2 and the inner surface of the shielding member 3 and / or the accommodating portion 60 can be made sufficiently short without impairing the function of the fuse element 2.

[0140] Furthermore, in such a protection element, the heat generated by the melting of the fuse element 2 decomposes the resin material forming the shielding member 3, case 6, and cover 4, generating pyrolysis gas, the heat of vaporization of which cools the inside of the housing 60 (the ablation effect of the resin). As a result, the arc discharge becomes even smaller. For these reasons, in a protection element in which the fuse element 2 is made of the above-mentioned laminate and the shielding member 3, case 6, and cover 4 are made of a resin material, the distance in the Z direction between the fuse element 2 and the inner surface of the shielding member 3 and / or housing 60 can be shortened, thereby further reducing the scale of the arc discharge and enabling even greater miniaturization.

[0141] Examples of resin materials that are likely to produce an ablation effect due to the heat generated by melting the fuse element 2 include nylon 46, nylon 66, polyacetal (POM), and polyethylene terephthalate (PET). From the viewpoints of heat resistance and flame retardancy, nylon 46 or nylon 66 is preferably used as the resin material forming the shielding member 3, case 6, and cover 4.

[0142] The ablation effect of the resin is more effectively achieved when the distance in the Y direction between the recess 68, the shielding member accommodating groove 34, and the fuse element mounting surface 65 that form the inner surface of the accommodating portion 60, and the distance in the Y direction between the first surface 31 of the shielding member 3 are 1.5 times or more the length in the Y direction (widths 21D, 22D) of the fuse element 2. This is presumably because, even when the inner surface of the shielding member 3 and / or the accommodating portion 60 is arranged in contact with the cutting portion 23 of the fuse element 2, the surface area of ​​the shielding member 3 and / or the surface area within the accommodating portion 60 becomes sufficiently large, accelerating the decomposition of the resin material due to the heat associated with the melting of the fuse element 2.

[0143] In contrast, for example, a protection element in which the fuse element is made of Cu and the case is made of a ceramic material may be difficult to miniaturize for the following reasons. That is, if the fuse element is made of Cu, the fuse element's melting point will be as high as 1000°C or higher. Therefore, if a resin material is used as the case material, the case may not have sufficient heat resistance. Therefore, a ceramic material, which has excellent heat resistance, is used as the case material.

[0144] In this protective element, the fuse element has a high fusing temperature and the case is made of a ceramic material. Therefore, if the distance between the fuse element's cutoff point and the inner surface of the case is short, the heat generated at the cutoff point will be dissipated through the case, making it difficult for the fuse element to reach its fusing temperature. For this reason, it is necessary to ensure a sufficient distance between the cutoff point and the inner surface of the case. Therefore, in a protective element with a fuse element made of Cu and a case made of a ceramic material, a large storage space must be provided inside the case.

[0145] Furthermore, if a sufficient distance is provided between the cutting portion and the inner surface of the case, the number of electric field lines generated by the arc discharge increases, resulting in a large-scale arc discharge occurring when the fuse element melts. For this reason, it may be necessary to place an arc-extinguishing agent in a storage compartment within the case to quickly extinguish the arc discharge. If an arc-extinguishing agent is placed in the case, it is necessary to secure space within the case to accommodate the arc-extinguishing agent. This requires the provision of a larger storage compartment within the case, which may make it even more difficult to reduce the size of the fuse.

[0146] [Second embodiment] (protective element) FIG. 14 is a cross-sectional view illustrating a protection element 200 according to a second embodiment, corresponding to a position obtained by cutting the protection element 100 according to the first embodiment along line AA′ in FIG. 1. FIG. 15 is a diagram illustrating the operation of the protection element 200 according to the second embodiment, corresponding to a position in the cross-sectional view shown in FIG. 14. FIG. 16 is a diagram illustrating the structure of a first shielding member 3a provided in the protection element 200 according to the second embodiment. FIG. 16(a) is a perspective view seen from the housing portion side, and FIG. 16(b) is a perspective view seen from the fuse element side. FIG. 17 is a plan view of a first case 6a provided in the protection element 200 according to the second embodiment, viewed from the housing portion side.

[0147] In the protection element 200 according to the second embodiment, the same members as those in the protection element 100 according to the first embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted. The protection element 200 of the second embodiment shown in Figure 14 differs from the protection element 100 of the first embodiment in that it is equipped with two springs 81, spring guide holes 82 provided in the first case 6a and the second case 6b, and spring receiving grooves 83 (see Figure 16) provided in the first shielding member 3a and the second shielding member 3b, respectively.

[0148] 14, the spring 81 arranged in contact with the first shielding member 3a is a pressing means that applies a force to the second surface 32 of the plate-shaped portion 30 of the first shielding member 3a in the rotational direction of the first shielding member 3a. The spring 81 arranged in contact with the second shielding member 3b is a pressing means that applies a force to the second surface 32 of the plate-shaped portion 30 of the second shielding member 3b in the rotational direction of the second shielding member 3b.

[0149] In this embodiment, the example of using a spring 81 as the pressing means has been described, but the pressing means need only be capable of applying force to the second surface 32 of the plate-shaped portion 30 in the rotational direction of the shielding member, and any known means capable of imparting elastic force can be used, and is not limited to a spring.

[0150] 14, spring 81 that applies force in the rotational direction of first shielding member 3a is accommodated in a compressed state in spring guide hole 82 provided in first case 6a. Spring 81 that applies force in the rotational direction of second shielding member 3b is accommodated in a compressed state in spring guide hole 82 provided in second case 6b.

[0151] The spring guide holes 82 are generally circular in plan view and are provided in the centers in the Y direction of the first bottom surfaces 68c of the recesses 68 of the first case 6a and the second case 6b (see FIG. 17). The spring guide holes 82 have a depth corresponding to the length of the springs 81 in a compressed state. The spring guide holes 82 allow the springs 81 to expand and contract along the inner wall surfaces of the spring guide holes 82, thereby expanding and contracting the springs 81 in the Z direction with high precision.

[0152] The second surface 32 of the plate-like portion 30 of the first shielding member 3a and the second shielding member 3b is provided with a spring receiving groove 83 against which the end of the spring 81 in the expansion / contraction direction comes into contact (see FIGS. 16(a) and 16(b)). The spring receiving groove 83 is a recess having a planar shape that combines a semicircle with a rectangle whose one side is the diameter of the semicircle, and is provided in the center in the Y direction of the end edge 32a of the second surface 32 in the X direction.

[0153] The bottom surface of the spring receiving groove 83 may be a flat surface, an inclined surface that gradually deepens toward the center of the first shielding member 3a or the second shielding member 3b in the X direction, or a surface that has a flat surface and the inclined surface formed continuously with the flat surface. When the bottom surface of the spring receiving groove 83 has the inclined surface, the bottom surface of the spring receiving groove 83 in the first shielding member 3a or the second shielding member 3b that is rotating and moving is closer to a surface perpendicular to the Z direction than when the bottom surface of the spring receiving groove 83 has a flat surface. This is preferable because it allows the pressing force in the Z direction caused by the restoring force of the spring 81 to be more reliably and sufficiently applied to the second surface 32 of the plate-like portion 30 of the first shielding member 3a or the second shielding member 3b that is rotating and moving.

[0154] (Protection element operation) Next, the operation of the protection element 200 according to the second embodiment when a current exceeding the rated current flows through the fuse element 2 in the protection element 200 will be described. When a current exceeding the rated current flows through the fuse element 2 of the protection device 200 of this embodiment, the fuse element 2 melts, causing an arc discharge, as in the protection device 100 of the first embodiment.

[0155] In the protection element 200 of this embodiment, similar to the protection element 100 of the first embodiment, a pressure increase in the accommodating portion 60 due to an arc discharge that occurs when the fuse element 2 melts down presses the first surface 31 of the plate-shaped portion 30 of the first shielding member 3a and the second shielding member 3b. At the same time, in the protection element 200 of this embodiment, as shown in FIG. 15 , the restoring force of the compressed spring 81 presses the second surface 32 of the plate-shaped portion 30, applying a force in the rotational direction of the first shielding member 3a and the second shielding member 3b. As a result, in the protection element 200 of this embodiment, the first shielding member 3a and the second shielding member 3b rotate about the rotation axis 33 with a stronger rotational force than in the protection element 100 of the first embodiment. Similarly to the protection element 100 of the first embodiment, the first end edge 31a is pressed against the bottom surface of the shielding member accommodating groove 34 provided on the inner surface of the accommodating portion 60. The second end side 31b is accommodated in the recess 68.

[0156] In the protection element 200 of this embodiment, similar to the protection element 100 of the first embodiment, the arc discharge generated when the fuse element 2 melts causes a pressure increase in the accommodating portion 60, which presses the first surfaces 31 of the first shielding member 3a and the second shielding member 3b. At the same time, in the protection element 200 of this embodiment, the spring 81 presses the second surface 32 of the plate-shaped portion 30, applying a force in the rotational direction of the first shielding member 3a and the second shielding member 3b. Due to the combined effect of these forces, the first shielding member 3a and the second shielding member 3b each rotate around the rotation axis 33, as shown in FIG. 15 . As a result, the inside of the accommodating portion 60 is more reliably blocked and divided at two locations in the X direction by the first shielding member 3a and the second shielding member 3b. Therefore, in the protection element 200 of this embodiment, the arc discharge generated when the fuse element 2 melts is more quickly extinguished (extinguished).

[0157] In the protective element 200 of this embodiment, the case where two springs 81 are provided has been described as an example, but only one spring 81 may be provided. Furthermore, in the protection element 200 of this embodiment, one spring 81 is provided each to apply a force in the rotational direction to the first shielding member 3a and the second shielding member 3b, one spring guide hole 82 is provided in the center in the Y direction of the first bottom surface 68c of the recess 68, and one spring receiving groove 83 is provided in the center in the Y direction of the second surface 32. However, the number of springs 81 and the positions of the spring guide holes 82 and the spring receiving groove 83 are not limited to the above example. For example, two springs may be provided each to apply a force in the rotational direction to the first shielding member 3a and / or the second shielding member 3b, and the two spring guide holes and spring receiving grooves may be arranged symmetrically with respect to the center in the Y direction. In this case, two springs apply a force in the rotational direction to each of the first shielding member 3a and the second shielding member 3b.

[0158] [Third embodiment] (protective element) Fig. 18 is a perspective view showing the overall structure of a protection element 300 according to the third embodiment. Fig. 19 is an exploded perspective view showing the overall structure of the protection element 300 shown in Fig. 18. Fig. 20 is a cross-sectional view of the protection element 300 according to the third embodiment taken along line BB' shown in Fig. 18. Fig. 21 is a diagram for explaining the operation of the protection element 300 of the third embodiment, and is a cross-sectional view at a position corresponding to the cross-sectional view shown in Fig. 20.

[0159] In the protection element 300 according to the third embodiment, the same members as those in the protection element 200 according to the second embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted. The protection element 300 of the third embodiment shown in FIG. 18 differs from the protection element 200 of the second embodiment in that, as shown in FIG. 19, two heat-generating members 5, power supply lines 54a, 54b, 55a, 55b, and power supply lead lines 54, 55 are provided, a heat-generating member accommodating recess 36 is provided in each of the first shielding member 3a and the second shielding member 3b, notches 76b in which the power supply lead lines 54, 55 are installed are provided in each of the first case 6a and the second case 6b, and a lead line groove 4b is provided in the cover 4.

[0160] In this embodiment, as shown in Figure 20, an example will be described in which two heat-generating members 5, a first heat-generating member 51 and a second heat-generating member 56, are provided, but only one of the two heat-generating members 5 may be provided.

[0161] As shown in Fig. 20, the first heat-generating member 51 is placed on the first surface 31 of the plate-shaped portion 30 of the first shielding member 3a. The second heat-generating member 56 is placed on the first surface 31 of the plate-shaped portion 30 of the second shielding member 3b. As shown in Fig. 20, the first heat-generating member 51 and the second heat-generating member 56 are placed opposite each other in positions close to the cutting portion 23 of the fuse element 2. The first heat-generating member 51 and the second heat-generating member 56 are placed symmetrically in the X direction with respect to the cutting portion 23. Therefore, the first heat-generating member 51 and the second heat-generating member 56 efficiently heat the cutting portion 23 of the fuse element 2.

[0162] Next, the structure of the first heat generating member 51 will be described with reference to Figure 22. The structure of the second heat generating member 56 is the same as that of the first heat generating member 51, and therefore description thereof will be omitted. Figure 22 is a drawing for explaining the structure of the first heat generating member 51 provided in the protection element 300 of the third embodiment, where Figure 22(a) is a cross-sectional view seen from the X direction, Figure 22(b) is a cross-sectional view seen from the Y direction, and Figure 22(c) is a plan view.

[0163] 22(a) to 22(c), the first heat generating member 51 is a plate-shaped member. The width of the first heat generating member 51 in the X direction is equal to or less than the width of the first shielding member 3a in the X direction. Furthermore, the width of the first heat generating member 51 in the Y direction is preferably wider than the width of the fuse element 2 in the Y direction. In this embodiment, the first heat-generating member 51 is a plate-shaped member, but the heat-generating member is not limited to a plate-shaped member and may be, for example, a wiring having a meandering pattern.

[0164] The first heat-generating member 51 includes an insulating substrate 51a, a heat-generating portion 51b, an insulating layer 51c, an element connection electrode 51d, and power supply line electrodes 51e and 51f. The first heat-generating member 51 heats and softens the cutting portion 23 of the fuse element 2. When an abnormality occurs in the external circuit that serves as the current path for the protection element 300, making it necessary to interrupt the current path, the first heat-generating member 51 generates heat when current is passed through it by a current control element provided in the external circuit. Furthermore, when the power supply lines 54a, 54b, 55a, and 55b melt after the fuse element 2 is cut, power supply to the first heat-generating member 51 is interrupted, and the first heat-generating member 51 stops generating heat.

[0165] As shown in FIGS. 22(a) to 22(c), the insulating substrate 51a has a generally rectangular shape in plan view with its long sides extending in the Y direction. As the insulating substrate 51a, a substrate having known insulating properties can be used, and examples thereof include those made of alumina, glass ceramics, mullite, zirconia, and the like.

[0166] As shown in FIGS. 22(a) to 22(c), the heat generating portion 51b is formed on the surface of the insulating substrate 51a facing the fuse element 2 (the underside in FIGS. 22(a) to 22(c)). As shown in FIG. 22(c), the heat generating portion 51b is provided in a strip shape extending in the Y direction along one long edge of the insulating substrate 51a, which is generally rectangular in plan view. The widths of the heat generating portion 51b in the X and Y directions are determined appropriately according to the widths of the cutting portion 23 of the fuse element 2 in the X and Y directions so that the cutting portion 23 can be efficiently heated. The heat generating portion 51b is preferably a resistor made of a conductive material that generates heat when current is applied via the power supply lines 54a and 54b. Examples of materials for the heat generating portion 51b include materials containing metals such as nichrome, W, Mo, and Ru.

[0167] 22(a) to 22(c), the power supply electrodes 51e and 51f are provided at the Y-direction ends of the insulating substrate 51a, and are provided at positions where portions thereof overlap with both end portions 51g and 51g of the heat generating portion 51b that face each other across the center of the heat generating portion 51b in a plan view. The power supply electrodes 51e and 51f are electrically connected to both end portions 51g and 51g of the heat generating portion 51b. The power supply electrodes 51e and 51f can be formed from a known electrode material.

[0168] The power supply electrode 51e is electrically connected to the power supply lead 55 via a power supply line 55a (see FIG. 19). The power supply electrode 51f is electrically connected to the power supply lead 54 via a power supply line 54a (see FIG. 19). The power supply electrodes 51e and 51f are intended to supply current to the heat generating portion 51b by a current control element provided in the external circuit when an abnormality occurs in the external circuit that serves as the current path for the protection element 300 and it becomes necessary to cut off the current path.

[0169] As shown in Figures 22(a) to 22(c), the insulating layer 51c is provided on the heat generating portion 51b. The insulating layer 51c is provided in the center of the insulating substrate 51a in the Y direction so as to cover the heat generating portion 51b and the connection portions between the heat generating portion 51b and the power supply electrodes 51e and 51f. The insulating layer 51c is not provided at the end portions of the insulating substrate 51a in the Y direction. As a result, parts of the power supply electrodes 51e and 51f are not covered by the insulating layer 51c and are exposed. The insulating layer 51c protects the heat generating portion 51b, efficiently transfers heat generated by the heat generating portion 51b to the fuse element 2, and insulates the heat generating portion 51b from the element connecting electrode 51d. The insulating layer 51c can be made of a known insulating material such as glass.

[0170] 22(a) to 22(c), the element connection electrode 51d is provided at a position where it at least partially overlaps the heat generating portion 51b with an insulating layer 51c interposed therebetween. The element connection electrode 51d can be made of a known electrode material. The element connection electrode 51d is electrically connected to the fuse element 2.

[0171] 22(a) to 22(c), the first heat generating member 51 has a heat generating portion 51b, an insulating layer 51c, an element connection electrode 51d, and power supply line electrodes 51e and 51f provided along one long side edge of an insulating substrate 51a that is generally rectangular in plan view, but these may also be provided along both long side edges of the insulating substrate 51a. In this case, for example, when electrically connecting the first heat generating member 51 and the power supply lines 54a and 55a, it is possible to prevent a decrease in yield caused by confusing an end portion where the power supply line electrodes 51e and 51f are not provided with the power supply line electrodes 51e and 51f.

[0172] 22(a) to 22(c) is disposed with the surface on the element connecting electrode 51d side facing the fuse element 2. Therefore, the insulating substrate 51a is not disposed between the heat generating portion 51b and the fuse element 2. Therefore, the heat generated in the heat generating portion 51b is conducted to the fuse element 2 more efficiently than when the insulating substrate 51a is disposed between the heat generating portion 51b and the fuse element 2.

[0173] The first heat-generating member 51 shown in Figures 22(a) to 22(c) can be manufactured, for example, by the following method. First, an insulating substrate 51a is prepared. Then, a paste-like composition containing a material that will become the heat-generating portion 51b and a resin binder is prepared. Then, the composition is screen-printed on the insulating substrate 51a to form a predetermined pattern, and the substrate is fired. This forms the heat-generating portion 51b.

[0174] Next, the power supply electrodes 51e and 51f are formed by a known method and electrically connected to both ends 51g of the heat generating portion 51b, respectively. Next, the insulating layer 51c is formed by a known method, and covers the heat generating portion 51b with the insulating layer 51c, and also covers the connection portions between the heat generating portion 51b and the power supply electrodes 51e and 51f. Thereafter, the element connection electrode 51d is formed on the insulating layer 51c by a known method. Through the above steps, the first heat generating member 51 shown in FIGS. 22(a) to 22(c) is obtained.

[0175] Figure 23 is a drawing for explaining another example of a heat-generating member, in which Figure 23(a) is a cross-sectional view of heat-generating member 52 as viewed from the X direction, and Figure 23(b) is a cross-sectional view of the center in the Y direction of heat-generating member 52 shown in Figure 23(a) as viewed from the Y direction. Figure 23(c) is a cross-sectional view of heat-generating member 53 as viewed from the X direction, and Figure 23(d) is a cross-sectional view of the center in the Y direction of heat-generating member 53 shown in Figure 23(c) as viewed from the Y direction.

[0176] In the protection element 300 of this embodiment, the heat generating member 52 shown in FIGS. 23(a) and 23(b) may be provided instead of the first heat generating member 51 (and / or the second heat generating member 56) shown in FIGS. 22(a) to 22(c). In the heat generating member 52 shown in FIGS. 23(a) and 23(b), the same components as those in the first heat generating member 51 shown in FIGS. 22(a) to 22(c) are denoted by the same reference numerals, and their description will be omitted. The planar arrangement of the components in the heat generating member 52 shown in FIGS. 23(a) and 23(b) is the same as the planar arrangement of the components in the first heat generating member 51 shown in FIGS. 22(a) to 22(c).

[0177] The heat generating member 52 shown in Figures 23(a) and 23(b) has an insulating substrate 51a, a heat generating portion 51b, an insulating layer 51c, an element connection electrode 51d, and power supply line electrodes 51e and 51f, similar to the first heat generating member 51 shown in Figures 22(a) to 22(c). As shown in Figures 23(a) and 23(b), the heat generating portion 51b is formed on the surface of the insulating substrate 51a opposite to the surface facing the fuse element 2 (the upper surface in Figures 23(a) and 23(b)).

[0178] 23(a) and 23(b), the power supply electrodes 51e and 51f are provided at the Y-direction ends of the insulating substrate 51a, similar to the first heat generating member 51 shown in FIGS. 22(a) to 22(c), and are provided at positions where portions overlap with both end portions 51g and 51g of the heat generating portion 51b in a plan view. The power supply electrodes 51e and 51f are electrically connected to both end portions 51g and 51g of the heat generating portion 51b.

[0179] As shown in Figures 23(a) and 23(b), the insulating layer 51c is provided on the heat generating portion 51b. The insulating layer 51c is provided in the center of the insulating substrate 51a in the Y direction so as to cover the heat generating portion 51b and the connection portions between the heat generating portion 51b and the power supply electrodes 51e and 51f. The insulating layer 51c is not provided at the end portions of the insulating substrate 51a in the Y direction. As a result, parts of the power supply electrodes 51e and 51f are not covered by the insulating layer 51c and are exposed. The insulating layer 51c protects the heat generating portion 51b.

[0180] As shown in FIGS. 23(a) and 23(b), the element connection electrode 51d of the heat generating member 52 is formed on the surface of the insulating substrate 51a opposite to the side on which the heat generating portion 51b is provided, unlike the first heat generating member 51 shown in FIGS. 22(a) to 22(c). Therefore, the element connection electrode 51d is disposed opposite the heat generating portion 51b across the insulating substrate 51a. The element connection electrode 51d is disposed in a position where at least a portion of the element connection electrode 51d overlaps with the heat generating portion 51b. Furthermore, the element connection electrode 51d is electrically connected to the fuse element 2, similar to the first heat generating member 51 shown in FIGS. 22(a) to 22(c).

[0181] In the protection element 300 of this embodiment, the first heat-generating member 51 (and / or the second heat-generating member 56) shown in FIGS. 22(a) to 22(c) may be replaced with the heat-generating member 53 shown in FIGS. 23(c) and 23(d). In the heat-generating member 53 shown in FIGS. 23(c) and 23(d), the same components as those in the first heat-generating member 51 shown in FIGS. 22(a) to 22(c) are denoted by the same reference numerals, and their description will be omitted. The arrangement of each component in the cross section of the heat-generating member 53 shown in FIGS. 23(c) and 23(d) when the center portion in the Y direction is viewed from the Y direction is the same as that of the first heat-generating member 51 shown in FIGS. 22(a) to 22(c).

[0182] The heat generating member 53 shown in Figures 23(c) and 23(d) has an insulating substrate 51a, a heat generating portion 51b, an insulating layer 51c, an element connection electrode 51d, and power supply line electrodes 51e and 51f, similar to the first heat generating member 51 shown in Figures 22(a) to 22(c). As shown in Figure 23(c), the heat generating portion 51b is formed on the surface (the underside in Figures 23(c) and 23(d)) of the insulating substrate 51a facing the fuse element 2. As shown in Figure 23(c), the heat generating portion 51b is provided in a strip shape extending in the Y direction along one long side edge from one end to the other end of the insulating substrate 51a, which is generally rectangular in plan view.

[0183] 23(c), an insulating layer 51c is provided on the heat generating portion 51b. The insulating layer 51c is provided in the center of the insulating substrate 51a in the Y direction so as to cover the region of the heat generating portion 51b except for both end portions 51g, 51g. Therefore, both end portions 51g, 51g of the heat generating portion 51b are not covered by the insulating layer 51c and are exposed. 23(c), the power supply electrodes 51e and 51f are provided at the Y-direction ends of the insulating substrate 51a and overlap both end portions 51g and 51g of the heat generating portion 51b in a plan view, thereby electrically connecting the power supply electrodes 51e and 51f to the heat generating portion 51b.

[0184] 23(c), the element connection electrode 51d is provided in an area on the insulating layer 51c excluding the areas where the power supply electrodes 51e and 51f are provided. As shown in FIG. 23(c), the element connection electrode 51d is arranged spaced apart from the power supply electrodes 51e and 51f. The element connection electrode 51d is provided in a position on the insulating layer 51c where it at least partially overlaps with the heat generating portion 51b.

[0185] Figure 24 is an enlarged view for explaining a portion of the protection element 300 of the third embodiment, and is an oblique view showing the fuse element 2, the first terminal 61, the second terminal 62, the first heat-generating member 51, the second heat-generating member 56, the power supply lines 54a, 54b, 55a, 55b, and the power supply lead lines 54, 55. 24, the first heat generating member 51 is electrically connected to the power supply lines 54a and 55a, and the second heat generating member 56 is electrically connected to the power supply lines 54b and 55b. In this embodiment, as shown in FIG. 24, the power feed lines 54a and 54b are electrically connected to the power feed lead line 54, and the power feed lines 55a and 55b are electrically connected to the power feed lead line 55.

[0186] In the present embodiment, the case where the power feed lines 54a and 54b are electrically connected to one power feed lead line 54 will be described as an example, but the power feed lines 54a and 54b may each be connected to a different power feed lead line. Also, the case where the power feed lines 55a and 55b are electrically connected to one power feed lead line 55 will be described as an example, but the power feed lines 55a and 55b may each be connected to a different power feed lead line.

[0187] In this embodiment, the power feeders 54a, 54b, 55a, and 55b are strip-shaped and are installed in side recesses 77a that form side vents 77 when the first case 6a and the second case 6b are integrated (see FIG. 19 ). The power feeders 54a, 54b, 55a, and 55b can be made of known conductive wiring materials. In this embodiment, the power feeders 54a, 54b, 55a, and 55b are strip-shaped, but the power feeders are not limited to being strip-shaped and may be linear. The power supply leads 54, 55 are formed of a conductive wiring material that is circular in cross section. The power supply leads 54, 55 are arranged symmetrically with respect to the fuse element 2. The power supply leads 54, 55 are each bent into a U-shape in plan view by bending.

[0188] The two bent portions 54c, 55c of each of the power feed leads 54, 55 are respectively disposed in notches 76b provided in the edges of the first case 6a and the second case 6b along the X direction (see FIG. 19 ). In this embodiment, since each of the power feed leads 54, 55 has the bent portions 54c, 55c, even if external stress is applied to the power feed leads 54, 55, the external stress is transmitted to the power feed lines 54a, 54b, 55a, 55b, and this prevents the electrical connection between the first heat-generating member 51 or the second heat-generating member 56 and the power feed lines 54a, 54b, 55a, 55b from being broken. The notch 76b is formed over the entire length (thickness) of the end member 72 in the X direction.

[0189] The end portions of the power supply lead wires 54, 55 beyond the bent portions 54c, 55c are exposed from the cover 4 while being held in lead wire grooves 4b provided in the cover 4 (see FIGS. 18 and 19). Two lead wire grooves 4b are formed in each of the openings on both sides of the cover 4, facing each other in the diametric direction. The width of the cover 4 in the circumferential direction of the lead wire groove 4b can be determined appropriately depending on the diameter of the power supply lead wires 54, 55.

[0190] Figure 25 is a diagram illustrating the structure of a first shielding member 3a provided in a protection element 300 of the third embodiment. Figure 25(a) is a perspective view seen from the accommodating portion 60 side, and Figure 25(b) is a perspective view seen from the fuse element 2 side. The first shielding member 3a provided in the protection element 300 of the third embodiment has a heat-generating member accommodating recess 36 that accommodates the heat-generating member 51. As shown in Fig. 25(b), the heat-generating member accommodating recess 36 is provided on the first surface 31 of the plate-shaped portion 30, close to the first end side 31a.

[0191] The width of the heat-generating component accommodating recess 36 in the X direction is determined according to the width of the heat-generating component 51 in the X direction. The width of the heat-generating component accommodating recess 36 in the Y direction is determined according to the width of the heat-generating component 51 in the Y direction. The depth (length in the Z direction) of the heat-generating component accommodating recess 36 is set so that the top of the plate-shaped portion 30 and the top of the heat-generating component 51 are flush with each other when the heat-generating component 51 is placed in the heat-generating component accommodating recess 36. In the protection element 300 of the third embodiment, as shown in Fig. 20, it is preferable that the first surface 31 of the plate-shaped portion 30 and the heat-generating component 51 are disposed in contact with the fuse element 2. This allows the heat-generating component 51 to efficiently heat the cutting portion 23, and the current path can be interrupted in a short time.

[0192] (Protection element manufacturing method) Next, a method for manufacturing the protection element 300 of this embodiment will be described with reference to the drawings. To manufacture the protection element 300 of this embodiment, first, a component (see Figure 7) is created in which the fuse element 2, the first terminal 61, and the second terminal 62 are integrated, in the same manner as the protection element 100 of the first embodiment.

[0193] 26(a), a linear conductive member 54d that will become the power feed lead 54 is prepared, and the power feed lines 54a and 54b are connected to the linear conductive member 54d by soldering. Also, a linear conductive member 55d that will become the power feed lead 55 is prepared, and the power feed lines 55a and 55b are connected to the linear conductive member 54d by soldering. Then, the power feeder 55a is soldered to the power feeder electrode 51e of the first heat-generating member 51, and the power feeder 54a is soldered to the power feeder electrode 51f. Furthermore, as shown in Fig. 26(a), the power feeder 55b is soldered to the power feeder electrode 51e of the second heat-generating member 56, and the power feeder 54b is soldered to the power feeder electrode 51f.

[0194] Furthermore, the first shielding member 3a is placed in the recess 68 of the first case 6a, and the second shielding member 3b is placed in the recess 68 of the second case 6b. 26(a), a component integrated with the fuse element 2, first terminal 61, second terminal 62, first heat-generating member 51, second heat-generating member 56, power supply lines 54a, 54b, 55a, 55b, and conductive members 54d, 55d is placed on the second case 6b on which the second shielding member 3b is placed. At this time, the second heat-generating member 56 is placed in the heat-generating member accommodating recess 36 of the second shielding member 3b.

[0195] 26(b), the first case 6a with the first shielding member 3a installed is placed on the second case 6b with the integrated members installed. At this time, the mating recess 63 of the first case 6a is fitted into the mating protrusion 67 of the second case 6b, and the mating protrusion 67 of the first case 6a is fitted into the mating recess 63 of the second case 6b.

[0196] 26(b), by placing the first case 6a on the second case 6b, a second buffer recess 75, a side vent 77, a first adhesive injection port 78, and a second adhesive injection port 76 are formed. As a result, the power supply lines 54a, 54b, 55a, and 55b pass through the side vent 77 and are connected to the conductive members 54d and 55d arranged outside the case 6. Also, as shown in FIG. 20, the first end 21 of the fuse element 2 is received in one insertion hole 64, and the second end 22 of the fuse element 2 is received in the other insertion hole 64, so that the first terminal 61 and the second terminal 62 connected to the fuse element 2 are partially exposed to the outside of the case 6.

[0197] Next, the first case 6a and the second case 6b are housed in an integrated state in the cover 4. As a result, the end members 72, the first buffering recesses 73, and the second buffering recesses 75 that form the side surfaces of the case 6 along the X direction are covered by the cover 4, and the first case 6a and the second case 6b are fixed together.

[0198] Thereafter, the conductive members 54d, 55d are fitted into the lead-out grooves 4b provided in the cover 4 and bent outward at approximately a right angle. As a result, two bent portions 54c, 55c (see FIG. 24) are formed in each of the conductive members 54d, 55d, to form the power supply lead-out wires 54, 55.

[0199] Thereafter, adhesive is injected into the inclined surface 4a of the cover 4, the first adhesive injection port 78, and the second adhesive injection port 76. This seals the inside of the cover 4, and the spatial region consisting of the storage section 60 and the internal pressure buffering space 71 is sealed by the outer surface of the case 6 and the inner surface of the cover 4. Through the above steps, the protective element 300 of this embodiment is obtained.

[0200] (Protection element operation) Next, the operation of the protection element 300 according to the third embodiment when a current exceeding the rated current flows through the fuse element 2 in the protection element 300 will be described. When a current exceeding the rated current flows through the fuse element 2 of the protection device 300 of this embodiment, the fuse element 2 generates heat and melts.

[0201] In the protection element 300 of this embodiment, similar to the protection element 200 of the second embodiment, a pressure increase inside the accommodating portion 60 due to an arc discharge that occurs when the fuse element 2 melts down presses the first surface 31 of the plate-shaped portion 30 of the first shielding member 3a and the second shielding member 3b. As shown in FIG. 21 , the restoring force of the compressed spring 81 presses the second surface 32 of the plate-shaped portion 30, applying a force in the rotational direction of the first shielding member 3a and the second shielding member 3b. As a result, in the protection element 300 of this embodiment, the first shielding member 3a and the second shielding member 3b rotate around the rotation axis 33. The first end edge 31a is pressed against the bottom surface of the shielding member accommodating groove 34 provided on the inner surface of the accommodating portion 60. The second end edge 31b is accommodated in the recess 68.

[0202] In the protection element 300 of this embodiment, similar to the protection element 200 of the second embodiment, an arc discharge generated when the fuse element 2 melts causes a pressure increase in the accommodating portion 60, which presses the first surfaces 31 of the first shielding member 3a and the second shielding member 3b. The spring 81 also presses the second surface 32 of the plate-shaped portion 30, applying a force in the rotational direction of the first shielding member 3a and the second shielding member 3b. Due to the combined effect of these forces, the first shielding member 3a and the second shielding member 3b each rotate about the rotation axis 33, as shown in FIG. 21 . As a result, the inside of the accommodating portion 60 is more reliably blocked and divided at two locations in the X direction by the first shielding member 3a and the second shielding member 3b. Therefore, in the protection element 300 of this embodiment, an arc discharge generated when the fuse element 2 melts is quickly extinguished (extinguished).

[0203] Furthermore, in the protection element 300 of this embodiment, the first heat-generating member 51 and the second heat-generating member 56 that heat the fuse element 2 are arranged in contact with the cutting portion 23 of the fuse element 2. Therefore, when an abnormality occurs in the external circuit that serves as the current path for the protection element 300 and it becomes necessary to cut off the current path, the first heat-generating member 51 and the second heat-generating member 56 are energized by a current control element provided in the external circuit, generating heat, which efficiently heats the cutting portion 23 and allows the current path to be cut off in a short time. Furthermore, after the fuse element 2 is cut, the power supply lines 54a, 54b, 55a, and 55b are cut due to the rotation of the first shielding member 3a and the second shielding member 3b and the melting of the soldered connections of the power supply line electrodes 51e and 51f caused by the heat generated by the first heat generating member 51 and the second heat generating member 56. As a result, the power supply to the first heat generating member 51 and the second heat generating member 56 is cut off, and the heat generation by the first heat generating member 51 and the second heat generating member 56 is stopped. Therefore, the protection element 300 of this embodiment has excellent safety.

[0204] [Other examples] The protective element of the present invention is not limited to the protective elements of the first and second embodiments described above. For example, in the protection element 100 of the first embodiment and the protection element 200 of the second embodiment described above, the cutting portion 23 is located near the center of the fuse element 2 in the X direction, the first shielding member 3a and the second shielding member 3b have the same shape, and the first case 6a and the second case 6b have the same shape. However, the position of the cutting portion does not have to be near the center of the fuse element in the X direction. In this case, the first shielding member 3a and the second shielding member 3b have different lengths in the X direction. Furthermore, the first case 6a has a housing shape that corresponds to the shape of the first shielding member 3a, and the second case 6b has a housing shape that corresponds to the shape of the second shielding member 3b. [Explanation of symbols]

[0205] 2 fuse elements 3 Shielding material 3a First shielding member 3b Second shielding member 4 Cover 4a Slope 4b Lead wire groove 5, 52, 53 Heat generating members 6 cases 6a Case 1 6b Second Case 21 First end 22 Second end 23 Cutting section (constricted section) 24a 1st bending part 24b 2nd bending part 25 1st connection part 26 2nd connection part 30 Plate-shaped part 33a Contact position 30a 1st area 30b 2nd area 31 Page 1 31a, 32a 1st edge 31b 2nd edge 32 2nd page 32b 2nd end face 33 Rotation axis 34 Shielding member accommodation groove 35 Leak prevention groove 36 Heat generating component receiving recess 38 Convex part 41 1st end 42 2nd end 51 First heat generating member 51a Insulating substrate 51b Heat generating part 51c Insulating layer 51d Element connecting electrode 51e, 51f feed line electrode 56 Second heat generating member 54, 55 Power supply lead wire 54a, 54b, 55a, 55b feed line 60 Storage section 61 1st terminal 61a, 62a External terminal holes 61c, 62c Tsubabe 62 2nd terminal 63 Fitting recess 64 Insertion hole 64a Insertion hole forming surface 64b Terminal mounting surface 65 Fuse element mounting surface 66 Guide hole 67 Fitting protrusion 68 Recess 68a First wall 68b Second wall 68c 1st bottom 68d Second bottom 69 Bottom vent 70 Joint surface 71 Internal pressure buffer space 72 End member 73 First buffer recess 74 Second recess 75 Second buffer recess 76 Second adhesive injection port 76a, 76b notch 77 Side vent 77a Side recess 78 First adhesive injection port 78a Notch 81 Spring 82 Spring guide hole 83 Spring receiving groove 100, 200, 300 protection element

Claims

1. a fuse element that is energized in a first direction from a first end toward a second end; a case made of an insulating material and having a housing portion therein for housing the fuse element, the case comprises a first case and a second case, the first case and the second case are disposed opposite to each other with respect to the fuse element, At least a portion of the case is covered with a cover, an internal pressure buffer space surrounded by an outer surface of the case and an inner surface of the cover is provided; the case has an air hole penetrating the case and communicating the storage section with the internal pressure buffer space, A protection element, wherein the volume of the internal pressure buffer space is equal to or greater than the volume of the fuse element.

2. 2. The protection element according to claim 1, wherein the case is made of any one of a nylon resin, a fluorine resin, and a polyphthalamide resin.

3. 3. The protection element according to claim 2, wherein the resin material is formed of a resin material having a tracking resistance index (CTI) of 400 V or more.

4. The protection element according to claim 2 , wherein the nylon resin does not contain a benzene ring.

5. the first end is electrically connected to a first terminal, and the second end is electrically connected to a second terminal; 5. The protection element according to claim 1, wherein a portion of the first terminal and a portion of the second terminal are exposed from the case.

6. 5. The protection element according to claim 1, wherein the fuse element is a laminate in which an inner layer made of a low-melting-point metal and an outer layer made of a high-melting-point metal are laminated in the thickness direction.

7. the low-melting-point metal is made of Sn or a metal containing Sn as a main component, 7. The protection element according to claim 6, wherein the high-melting-point metal is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

8. 5. The protection element according to claim 1, wherein a heat generating member that heats the fuse element is provided, and the heat generating member has an element connection electrode electrically connected to the fuse element.

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