Protection element

Abstract

To provide a protection element that can be miniaturized such that arc discharge generated when a fuse element is blown is small.SOLUTION: A protection element 100 includes a fuse element 2 having a cutting portion 23 between a first end portion 21 and a second end portion 22 and being energized in the first direction from the first end portion 21 to the second end portion 22, and a case 6 that is made of an insulating material and has an accommodating portion 60 inside which the cutting portion 23 is housed, and a length H23 in the thickness direction of the cutting portion 23 in the first direction cross section is equal to or less than the length in the width direction intersecting the thickness direction in the first direction cross section, and a first wall surface 60c and a second wall surface 60d facing in the thickness direction are provided in the accommodating portion 60, and a distance H6 in the thickness direction between the first wall surface 60c and the second wall surface 60d is 10 times or less the length H23 in the thickness direction of the cutting portion 23.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Conventionally, there is a fuse element that generates heat and melts to cut off a current path when a current exceeding the rated value flows through the current path. Protective devices (fuse elements) equipped with the fuse element are used in a wide range of fields, such as electric vehicles.

[0003] For example, Patent Document 1 describes a fuse element that is mainly used in automotive electric circuits, etc. Patent Document 1 describes a fuse element that includes two elements connected between terminals located at both ends and a melting part provided in the approximate center of the elements. Patent Document 1 also describes a fuse in which a pair of fuse elements is stored inside a casing and an arc-extinguishing material is enclosed between the fuse elements and the casing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-004634 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a protection element installed in a current path of high voltage and large current, an arc discharge is likely to occur when the fuse element melts. If a large-scale arc discharge occurs, the case in which the fuse element is housed may be destroyed. For this reason, in conventional technology, the higher the voltage and current of the current path in which the protection element is installed, the larger the case in which the protection element is housed.

[0006] However, the larger the case that houses the fuse element, the more material is required for the case. Also, there is a demand for the protection element to be small and lightweight. The present invention has been made in view of the above circumstances, and has an object to provide a protection element that can be made compact and that reduces the scale of arc discharge that occurs when a fuse element melts. [Means for solving the problem]

[0007] In order to solve the above problems and obtain a small-sized protective element that generates a small-scale arc discharge when the fuse element melts, the inventors focused on the size of the accommodation portion in the case that houses the cutting portion of the fuse element and conducted extensive research as described below. That is, as described below, a fuse element having a thickness of 0.2 mm and a width of 6.5 mm was placed inside the housing of the case, and a protective element A was manufactured in which the distance of the fuse element in the thickness direction within the housing was 0.75 mm. The protective element A was then placed in a current path with a voltage of 150 V and a current of 190 A, and a current interruption was performed.

[0008] In addition, protective element B was manufactured, which was equipped with the same fuse element as protective element A, but with the thickness-wise distance of the fuse element within the housing of the case set to 14 mm, and was installed in a current path with a voltage of 150 V and a current of 190 A to interrupt the current. As a result, a large-scale arc discharge occurred in protection element B. On the other hand, the arc discharge in protection element A was very small compared to protection element B. This is presumably due to the following reasons.

[0009] Fig. 15 is a diagram for explaining the electric field line density at the cut portion of the fuse element in protection element A. Fig. 16 is a diagram for explaining the electric field line density at the cut portion of the fuse element in protection element B. 15 and 16, reference numeral 2 indicates the fuse element, reference numeral 61 indicates the first terminal, and reference numeral 62 indicates the second terminal. Reference numeral 6 indicates the case. Reference numeral 4 indicates electric field lines. Electric field lines are lines that indicate Q / ε "strands" of charges coming out of the charge Q "C" and Q / ε "strands" of charges entering the charge -Q "C".

[0010] The fuse element A and the protection element B have the same fuse element and the same voltage and current at the time of interruption, so the density of the electric field lines generated by the arc discharge is the same. For this reason, as shown in Figs. 15 and 16, it is estimated that the longer the distance in the thickness direction of the fuse element in the housing of the case 6, the greater the number of electric field lines 4, and the shorter the distance, the fewer the number of electric field lines 4. In other words, since the charges (thermal electrons) are of the same polarity (negative) and repel each other, under the same discharge conditions, the distance between the charges (density of the electric field lines) is the same regardless of the distance. From this, it is estimated that if the distance is long, the amount of moving charge is large and the arc discharge is large, and if the distance is short, the amount of moving charge is small and the arc discharge is small.

[0011] Based on the above findings, the inventors have further investigated the relationship between the distance in the thickness direction of the cutting portion of the fuse element within the housing of the case and the thickness of the cutting portion, and have confirmed that the distance in the thickness direction of the cutting portion within the housing of the case should be 10 times or less the thickness of the cutting portion.

[0012] Furthermore, the inventors conducted extensive research based on the above findings and discovered that in a protection element in which the thickness-wise distance of the cut portion within the housing portion of the case is 10 times or less than the thickness of the cut portion, by arranging at least one of the wall surfaces in the thickness direction of the fuse element within the housing portion of the case in contact with the cut portion, the arc discharge can be made small-scale. This is presumably because, when the cutting portion that contacts the inside of the housing portion of the case is blown, the number of electric field lines generated by the arc discharge decreases and the fuse element is cooled.

[0013] Furthermore, the inventors focused on the relationship between the widthwise distance of the fuse element within the housing portion of the case and arc discharge in a protection element in which the thicknesswise distance of the cut portion within the housing portion of the case is 10 times or less the thickness of the cut portion, and conducted extensive research. As a result, it was found that the arc discharge is suppressed and becomes smaller as the widthwise distance of the fuse element within the housing of the case is longer. This is presumably because, when the thicknesswise distance of the cutting portion within the housing of the case is the same, increasing the widthwise distance of the fuse element within the housing of the case suppresses the increase in pressure within the housing when the fuse element melts, and has the effect of suppressing the increase in the density of electric field lines generated by the arc discharge.

[0014] Based on these findings, the present inventors have arrived at the present invention. In order to solve the above problems, the present invention proposes the following means.

[0015] [1] A fuse element having a cut portion between a first end and a second end, and energized in a first direction from the first end to the second end; a case made of an insulating material and having a housing portion therein for housing the cutting portion, a length in a thickness direction of the cut portion in the first direction cross section is equal to or less than a length in a width direction intersecting with the thickness direction in the first direction cross section, A first wall surface and a second wall surface opposed to each other in the thickness direction are provided in the storage portion, A protective element, wherein the distance in the thickness direction between the first wall surface and the second wall surface is 10 times or less the length in the thickness direction of the cut portion.

[0016] [2] The protection element according to [1], wherein the distance in the thickness direction between the first wall surface and the second wall surface is 5 times or less the length in the thickness direction of the cut portion. [3] The protection element according to [1], wherein the distance in the thickness direction between the first wall surface and the second wall surface is not more than twice the length in the thickness direction of the cut portion.

[0017] [4] The protection element according to any one of [1] to [3], wherein the cut portion is disposed in contact with one or both of the first wall surface and the second wall surface. [5] A third wall surface and a fourth wall surface opposed to each other in the width direction are provided within the storage portion, The protection element according to any one of [1] to [4], wherein the distance in the width direction between the third wall surface and the fourth wall surface is 1.5 times or more the length in the width direction of the fuse element. [6] The protection element according to [5], wherein the distance in the width direction between the third wall surface and the fourth wall surface is 2 to 5 times the length in the width direction of the fuse element.

[0018] [7] The protection element according to any one of [1] to [6], wherein the fuse element is flat or linear. [8] The protection element according to any one of [1] to [7], wherein the first end is electrically connected to a first terminal, and the second end is electrically connected to a second terminal.

[0019] [9] The protection element according to any one of [1] to [8], wherein the melting temperature of the fuse element is 600° C. or lower.

[10] The protection element according to any one of [1] to [8], wherein the melting temperature of the fuse element is 400° C. or lower.

[0020]

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

[10] , 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.

[12] The low melting point metal is made of Sn or a metal mainly composed of Sn, The protection element according to

[11] , wherein the high-melting point metal is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

[0021]

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

[12] , wherein the case is formed of a resin material having a tracking resistance index CTI of 400 V or more.

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

[12] , wherein the case is formed of a resin material having a tracking resistance index CTI of 600 V or more.

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

[14] , wherein the case is made of any one selected from the group consisting of nylon-based resins, fluorine-based resins, and polyphthalamide resins.

[16] The protective element according to

[15] , wherein the nylon-based resin is a resin that does not contain a benzene ring. Effect of the Invention

[0022] In the protective element of the present invention, a first wall surface and a second wall surface facing each other in the thickness direction of the cut portion of the fuse element are provided in the housing portion of the case, and the distance in the thickness direction between the first wall surface and the second wall surface is 10 times or less than the length in the thickness direction of the cut portion. Therefore, the arc discharge generated when the fuse element melts is small. Therefore, the protective element of the present invention can be preferably installed in a current path of a high voltage of 100V or more and a large current of 100A or more, for example. In addition, the protective element of the present invention can be miniaturized because the distance in the thickness direction between the first wall surface and the second wall surface is short. Furthermore, the protective element of the present invention can be miniaturized by reducing the thickness between the housing portion and the outer surface of the case because the arc discharge is small. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a perspective view showing the overall structure of a protection element 100 according to the first embodiment. [Diagram 2] FIG. 2 is an exploded perspective view showing the overall structure of the protection element 100 shown in FIG. [Diagram 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(a) is an enlarged view for explaining a part of the protection element 100 of the first embodiment, and is a plan view showing the fuse element, the first terminal, and the second terminal. Fig. 4(b) is a plan view for explaining the positional relationship between the first case, the second case, the fuse element, the first terminal, and the second terminal. [Diagram 5] Fig. 5 is a diagram for explaining the structure of a first case provided in the protection element 100 of the first embodiment. Fig. 5(a) is a plan view seen from the housing part side, Fig. 5(b) is a perspective view seen from the housing part side, and Fig. 5(c) is a perspective view seen from the outer surface side. [Figure 6] Fig. 6 is a diagram for explaining the structure of the second case provided in the protection element 100 of the first embodiment. Fig. 6(a) is a plan view seen from the housing part side, Fig. 6(b) is a perspective view seen from the housing part side, and Fig. 6(c) is a perspective view seen from the outer surface side. [Figure 7] FIG. 7 is a cross-sectional view for explaining a protection element 200 according to the second embodiment, and is a cross-sectional view corresponding to a position where the protection element 100 according to the first embodiment is cut along the line AA' shown in FIG. [Figure 8] FIG. 8 is a photograph showing the state in which the fuse element used in protection element A, the first terminal, and the second terminal are integrated together, placed on the second case. [Figure 9] FIG. 9 is a photograph of an arc discharge when protective element B, which is a comparative example, is interrupted at a voltage of 150 V and a current of 190 A. [Figure 10] FIG. 10 is a photograph of the state of protection element B, which is a comparative example, after current interruption. [Figure 11] FIG. 11 is a photograph of an arc discharge when protective element A, which is an example of the present invention, is interrupted at a voltage of 150 V and a current of 190 A. [Figure 12] FIG. 12 is a photograph of the protective element A according to the embodiment after current interruption. [Figure 13] FIG. 13 is a diagram showing the measurement results of the protective elements of Examples 1 to 3 and the evaluation results when interrupting at a voltage of 150 V and a current of 2000 A. [Figure 14]FIG. 14 is a graph showing the measurement results of the protective elements of Example 4, Example 5, and Comparative Example 1, and the evaluation results when the protective elements were interrupted at a voltage of 150 V and a current of 2000 A. [Figure 15] FIG. 15 is a diagram for explaining the electric field line density at the cut portion of the fuse element in the protection element A. In FIG. [Figure 16] FIG. 16 is a diagram for explaining the electric field line density at the cut portion of the fuse element in the protection element B. In FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] 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 parts in an enlarged scale for the sake of convenience in order to make the characteristics easier to understand, 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. They may be modified as appropriate within the scope of the effects of the present invention.

[0025] [First embodiment] (Protection element) 1 to 3 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 flow 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.

[0026] Fig. 1 is a perspective view showing the overall structure of a protection element 100 according to a 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. As shown in FIGS. 1 to 3, the protection element 100 of this embodiment includes a fuse element 2 and a case 6 having an accommodating portion 60 therein for accommodating the cutting portion 23 of the fuse element 2. As shown in FIG.

[0027] (Fuse element) Fig. 4(a) is an enlarged view for explaining a part of the protection element 100 of the first embodiment, and is a plan view showing the fuse element, the first terminal, and the second terminal. Fig. 4(b) is a plan view for explaining the positional relationship between the first case, the second case, the fuse element, the first terminal, and the second terminal.

[0028] 4(a), the fuse element 2 is flat and has a first end 21, a second end 22, and a cutting portion 23 provided between the first end 21 and the second end 22. Electricity flows through the fuse element 2 in an X-direction (first direction) that is a direction from the first end 21 to the second end 22. 3 and 4(a), the first end 21 is electrically connected to a first terminal 61. The second end 22 is electrically connected to a second terminal 62.

[0029] The first terminal 61 and the second terminal 62 may have substantially the same shape as shown in Figures 1 to 3 and 4(a), or may have different shapes. The thicknesses of the first terminal 61 and the second terminal 62 are not particularly limited, but may be approximately 0.3 to 1.0 mm. The thicknesses of the first terminal 61 and the second terminal 62 may be the same as or different from each other, as shown in Figure 3. As shown in Figures 1 to 4(a), 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 a power source side, and the other is used for connecting to a load side. As shown in Figures 1 to 4(a), the external terminal hole 61a and the external terminal hole 62a can be through holes that are approximately circular in plan view.

[0030] 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, it is preferable to use brass as the material for the first terminal 61 and the second terminal 62, and from the viewpoint of reducing electrical resistance, it is preferable to use copper. The first terminal 61 and the second terminal 62 may be made of the same material or different materials.

[0031] The shape of the first terminal 61 and the second terminal 62 is not particularly limited as long as it can be engaged with a terminal on the power source side or a terminal on the load side (not shown), and may be, for example, a claw shape with an open portion, or may have flanges (indicated by symbols 61c and 62c in FIG. 4(a)) that are widened on both sides toward the fuse element 2 at the end connected to the fuse element 2 as shown in FIG. 4(a). When the first terminal 61 and the second terminal 62 have the 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.

[0032] The fuse element 2 shown in Fig. 3 has a uniform thickness (length in the Z direction, indicated by reference symbol H23 in Fig. 3). 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. When an overcurrent flows in such a fuse element 2, the cutting portion 23 becomes a heat spot, and the cutting portion 23 is preferentially heated and softened, resulting in more reliable cutting.

[0033] As shown in FIG. 4(a), the planar shape of the entire fuse element 2 is substantially rectangular, and compared with a general fuse element, the width 23D in the Y direction of the cut portion 23 is relatively wide and the length 2L in the X direction is relatively short. In the protection element 100 of this embodiment, the arc discharge generated when the fuse element 2 melts is small-scale, so that the arc discharge is quickly extinguished (extinguished). Therefore, in order to suppress the arc discharge, it is not necessary to narrow the width 23D in the Y direction of the cut portion 23 in the fuse element 2, and the width 23D in the Y direction of the cut portion 23 in the fuse element 2 can be made wide and the length 2L in the X direction can be made short. The protection element 100 having such a fuse element 2 can suppress the increase in resistance value in the current path in which the protection element 100 is installed. Therefore, the protection element 100 of this embodiment can be preferably installed in a current path of a large current.

[0034] As shown in Fig. 4(a), the fuse element 2 has a generally rectangular shape in a plan view. As shown in Fig. 4(a), 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. 4(a) means the widths 21D and 22D in the Y direction of the first end 21 and the second end 22.

[0035] 1, 3, and 4(a), the first end 21 of the fuse element 2 is disposed so as to overlap the first terminal 61 in a plan view. Moreover, the second end 22 of the fuse element 2 is disposed so as to overlap the second terminal 62 in a plan view. As shown in Fig. 4(a), the length in the X direction at the first end 21 extends from the region overlapping with the first terminal 61 in a plan view toward the cutting portion 23. Also, as shown in Fig. 4(a), the length in the X direction at the second end 22 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. 4(a), the length in the X direction at the second end 22 is longer than the length in the X direction at the first end 21.

[0036] In the present embodiment, the fuse element 2 has been described as having a length in the X direction at the second end 22 that is longer than the length in the X direction at the first end 21, but the length in the X direction at the first end 21 and the length in the X direction at the second end 22 may be the same. In other words, in the present embodiment, the cutting portion 23 is disposed away from the center of the fuse element 2 in the X direction toward the first terminal 61, but the cutting portion 23 may be disposed at the center of the fuse element 2 in the X direction.

[0037] As shown in FIG. 4(a), a first connecting portion 25 having a substantially trapezoidal shape in plan view is disposed between the cutting portion 23 and the first end portion 21. The longer of the parallel sides of the first connecting portion 25 having a substantially trapezoidal shape in plan view is connected to the first end portion 21. In addition, a second connecting portion 26 having a substantially trapezoidal shape in plan view is disposed between the cutting portion 23 and the second end portion 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 portion 21 and the second end portion 22. As a result, when an overcurrent flows through the fuse element 2, the cutting portion 23 becomes a heat spot, and the cutting portion 23 is preferentially heated and softened, and is easily cut.

[0038] 4(a), the width 23D in the Y direction at the cutting portion 23 of the fuse element 2 is narrower than the widths 21D, 22D in the Y direction of the first end 21 and the second end 22. Therefore, 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. This makes the cutting portion 23 easier to cut 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.

[0039] As shown in Figures 1 to 4(a), the cutting portion 23 of the fuse element 2 is plate-shaped, and the length H23 in the thickness direction (Z direction) in the X-direction (first direction) cross section of the cutting portion 23 shown in Figure 3 is less than or equal to the length (width 23D) in the width direction (Y direction) intersecting the Z direction in the X-direction cross section shown in Figure 4(a).

[0040] In this embodiment, as shown in FIG. 4(a), the fuse element 2 has been described as having a Y-direction width 23D at the cut portion 23 that is narrower than the Y-direction widths 21D, 22D of the first end portion 21 and the second end portion 22. However, the fuse element may have a Y-direction width of the cut portion that is the same as the first end portion and the second end portion, and is not limited to a fuse element having a Y-direction width of the cut portion that is narrower than the first end portion and the second end portion. 4(a), 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 length of the thickness direction (Z direction) of the cut portion of the fuse element in the X direction (first direction) cross section is the same as the length of the width direction (Y direction) intersecting with the Z direction in the X direction cross section.

[0041] Materials used for known fuse elements, such as metal materials containing alloys, can be used as the material for the fuse element 2. Specifically, examples of the material for the fuse element 2 include alloys such as Pb85% / Sn and Sn / Ag3% / Cu0.5%.

[0042] 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.

[0043] The low melting point metal used as the material of the fuse element 2 is preferably Sn or a metal mainly composed of Sn. Since the melting point of Sn is 232°C, a metal mainly composed of Sn has a low melting point and becomes soft at low temperatures. For example, the solidus of a Sn / Ag3% / Cu0.5% alloy is 217°C.

[0044] It is preferable to use Ag or Cu, or a metal mainly composed of Ag or Cu, as the high melting point metal used as the material of the fuse element 2. For example, since the melting point of Ag is 962°C, a layer made of a metal mainly composed of Ag maintains its rigidity at a temperature at which a layer made of a low melting point metal becomes soft.

[0045] 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 generated when the fuse element 2 melts becomes smaller in scale.

[0046] The fuse element 2 can be manufactured by a known method. For example, 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 laminated in the thickness direction, 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 by plating to obtain a laminate. The laminate is then cut into a predetermined shape. Through the above steps, the fuse element 2 made of a three-layer laminate is obtained.

[0047] (case) As shown in Figs. 1 to 3, the case 6 is a substantially rectangular parallelepiped, and is formed by integrating two members, a first case 6a and a second case 6b disposed opposite the first case 6a. As shown in FIGS. 1 to 3, the cutting portion 23 of the fuse element 2 is housed in a housing portion 60 provided inside the case 6.

[0048] 3, a first insertion hole 64 opening to the fifth wall surface 60e is provided in the housing portion 60, and a second insertion hole 65 opening to the sixth wall surface 60f is provided in the housing portion 60. The first insertion hole 64 and the second insertion hole 65 are formed by joining the second case 6b and the first case 6a in an opposing arrangement. 3, the first end 21 of the fuse element 2 is housed in the first insertion hole 64. Furthermore, the second end 22 of the fuse element 2 is housed in the second insertion hole 65. As shown in FIGS. 1 to 3, a first terminal 61 and a second terminal 62 connected to the fuse element 2 are partially exposed to the outside of the case 6.

[0049] Fig. 5 is a drawing for explaining the structure of a first case provided in the protection element 100 of the first embodiment. Fig. 5(a) is a plan view seen from the housing part side, Fig. 5(b) is a perspective view seen from the housing part side, and Fig. 5(c) is a perspective view seen from the outer surface side. Fig. 6 is a drawing for explaining the structure of a second case provided in the protection element 100 of the first embodiment. Fig. 6(a) is a plan view seen from the housing part side, Fig. 6(b) is a perspective view seen from the housing part side, and Fig. 6(c) is a perspective view seen from the outer surface side.

[0050] 1 and 3, the case 6 in the protection element 100 of this embodiment is provided with a substantially rectangular parallelepiped accommodation section 60 therein for accommodating the cutting section 23 of the fuse element 2. The accommodation section 60 may be formed by bonding a first case 6a and a second case 6b together. Furthermore, the first case 6a and the second case 6b may be fixed together by a cover (not shown) disposed on the outside of the case 6.

[0051] As shown in FIG. 3, the storage section 60 is provided with a first wall surface 60c and a second wall surface 60d, which are flat surfaces facing each other in the thickness direction (Z direction) of the cutting section 23. As shown in FIG. 4(b), FIG. 5(a), FIG. 5(b), FIG. 6(a), and FIG. 6(b), the storage section 60 is provided with a third wall surface 60g and a fourth wall surface 60h, which are flat surfaces facing each other in the width direction (Y direction) of the cutting section 23. As shown in FIG. 3, FIG. 4(b), FIG. 5(a), FIG. 5(b), FIG. 6(a), and FIG. 6(b), the storage section 60 is provided with a fifth wall surface 60e and a sixth wall surface 60f, which are flat surfaces facing each other in the (X direction). The third wall surface 60g and the fourth wall surface 60h, the fifth wall surface 60e, and the sixth wall surface 60f are each made into a continuous flat surface by fixing the first case 6a and the second case 6b.

[0052] In this embodiment, as shown in Fig. 3, the fuse element 2 is placed on the second wall surface 60d. As a result, the entire surface 23b of the cutting portion 23 of the fuse element 2 facing the second wall surface 60d is disposed in contact with the second wall surface 60d.

[0053] 3, in the protection element 100 of this embodiment, a space 60a is provided between the fuse element 2 and the first wall surface 60c, and the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d is set to be 10 times or less the length H23 in the Z direction of the cutting portion 23. Therefore, the number of electric field lines generated by the arc discharge is sufficiently reduced, and the arc discharge generated when the fuse element 2 melts is small. In addition, since the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d is short, the protection element 100 can be made compact.

[0054] In the protection element 100 of this embodiment, the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d is preferably 5 times or less, and more preferably 2 times or less, the length H23 in the Z direction of the cutting portion 23, because the arc discharge becomes smaller and the size can be further reduced. The distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d can be determined according to the application of the protection element 100, such as the installation space of the protection element 100 and the voltage and current of the current path in which the protection element 100 is installed.

[0055] In the protection element 100 of this embodiment, as shown in FIG. 4(b), the center position of the length between the third wall surface 60g and the fourth wall surface 60h is arranged so as to substantially coincide with the center position of the fuse element 2 in the Y direction. The positional relationship in the Y direction between the fuse element 2 and the accommodating portion 60 is preferably such that the center position of the length between the third wall surface 60g and the fourth wall surface 60h approximately coincides with the center position of the fuse element 2 in the Y direction, as shown in Figure 4(b). However, the positional relationship in the Y direction between the fuse element 2 and the accommodating portion 60 is not limited to the example shown in Figure 4(b) and can be determined appropriately depending on the shape of the fuse element 2, etc.

[0056] In the protection element 100 of this embodiment, the distance 60D (see FIG. 4(b)) in the width direction (Y direction) of the cut portion 23 between the third wall surface 60g and the fourth wall surface 60h is preferably 1.5 times or more the length in the Y direction (widths 21D, 22D) of the fuse element 2. When the distance 60D in the Y direction between the third wall surface 60g and the fourth wall surface 60h is 1.5 times or more the widths 21D, 22D of the fuse element 2, the pressure rise in the accommodating portion 60 when the fuse element 2 melts is suppressed, and arc discharge is effectively suppressed. It is more preferable that the distance 60D in the Y direction between the third wall surface 60g and the fourth wall surface 60h is twice or more the widths 21D, 22D of the fuse element 2.

[0057] In the protection element 100 of this embodiment, the distance 60D in the Y direction between the third wall surface 60g and the fourth wall surface 60h is preferably 5 times or less, and more preferably 4 times or less, the widths 21D, 22D of the fuse element 2. When the distance 60D in the Y direction between the third wall surface 60g and the fourth wall surface 60h is 5 times or less the widths 21D, 22D of the fuse element 2, the distance 60D is not too long, which does not hinder the miniaturization of the protection element 100.

[0058] In the protection element 100 of this embodiment, as shown in FIG. 4(b), the center position of the X-direction length 2L excluding the area overlapping with the first terminal 61 and the second terminal 62 in a planar view of the fuse element 2 is arranged so as to substantially coincide with the center position of the X-direction length 6L between the fifth wall surface 60e and the sixth wall surface 60f. The positional relationship between the fuse element 2 and the accommodating portion 60 in the X direction is not limited to the example shown in FIG. 4(b) and can be appropriately determined depending on the position of the cutting portion 23 of the fuse element 2 in the X direction, etc.

[0059] In the protection element 100 of this embodiment, the distance 6L (see FIG. 4(b)) in the first direction (X direction) of the cutting portion 23 between the fifth wall surface 60e and the sixth wall surface 60f may be equal to or greater than the length of the cutting portion 23 in the X direction, and is more preferably equal to or greater than four times the length of the cutting portion 23 in the X direction. The distance 6L between the fifth wall surface 60e and the sixth wall surface 60f is appropriately determined according to the length of the cutting portion 23 in the X direction. The length of the cutting portion 23 in the X direction is a factor that determines the resistance value (rated current) of the fuse element 2. Therefore, the length of the cutting portion 23 in the X direction is appropriately set according to the desired overcurrent interruption characteristics, and it is better to have a shorter length.

[0060] Moreover, it is preferable that the distance 6L in the X direction between the fifth wall surface 60e and the sixth wall surface 60f is equal to or less than the length 2L in the X direction of the fuse element 2 excluding the region overlapping with the first terminal 61 and the second terminal 62 in a plan view. When the first terminal 61 and the second terminal 62 are exposed in the accommodating portion 60, an arc discharge also occurs between the first terminal 61 and the second terminal 62. For this reason, it is preferable that the distance 6L is equal to or less than the length 2L in the X direction of the fuse element 2 excluding the region overlapping with the first terminal 61 and the second terminal 62 in a plan view, and the arc discharge between the first terminal 61 and the second terminal 62 is reliably shielded by the insertion hole forming surfaces 64c, 65c.

[0061] The second case 6b is a substantially rectangular parallelepiped, and has a second protruding portion 68b forming the storage portion 60, as shown in FIG. 3, FIG. 6(a) and FIG. 6(b). The second protruding portion 68b is rectangular in plan view, as shown in FIG. 6(a) and FIG. 6(b). As shown in FIG. 3, the first short side of the second protruding portion 68b becomes an end face of the third wall surface 60g, the second short side becomes an end face of the fourth wall surface 60h, the first long side becomes an end face of the fifth wall surface 60e, and the second long side becomes an end face of the sixth wall surface 60f, by being joined to the first case 6a. The top of the second protruding portion 68b becomes the second wall surface 60d by being joined to the first case 6a.

[0062] 6(a) and 6(b), a leak prevention groove 67c is provided along the fifth wall surface 60e at the joint between the second wall surface 60d and the fifth wall surface 60e and along the sixth wall surface 60f at the joint between the second wall surface 60d and the sixth wall surface 60f. The two leak prevention grooves 67c are arranged opposite each other in the X direction in a plan view. When the molten fuse element 2 is blown and the molten fuse element 2 scatters and the scattered matter adheres to the inside of the housing portion 60, the leak prevention groove 67c cuts off the electric path formed by the scattered matter to prevent leakage current.

[0063] In the protection element 100 of this embodiment, it is preferable that the leak prevention groove 67c is provided, but the leak prevention groove 67c may not be provided. In addition, the position where the leak prevention groove 67c is provided is preferably provided along the joint portion of the second wall surface 60d with the fifth wall surface 60e and the joint portion of the second wall surface 60d with the sixth wall surface 60f, but it may be provided at another position on the second protrusion 68b, or only one of the two leak prevention grooves 67c may be provided. When the leak prevention groove 67c is provided along the joint portion of the second wall surface 60d with the fifth wall surface 60e and the joint portion of the second wall surface 60d with the sixth wall surface 60f, it is possible to effectively prevent the scattered matter attached to the inside of the housing portion 60 when the fuse element 2 melts from being electrically connected to the first terminal 61 or the second terminal 62, and it is possible to effectively prevent the formation of a new electric path.

[0064] 4(b), the length in the Y direction of the leak prevention groove 67c is preferably longer than 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 of the fuse element 2. In this case, it is possible to more effectively prevent the scattered matter adhering to the inside of the housing portion 60 when the fuse element 2 melts from being electrically connected to the first terminal 61 or the second terminal 62, and it is possible to more effectively prevent the occurrence of a leak current. The leak prevention groove 67c is formed to have a substantially constant width and depth. The width and depth of the leak prevention groove 67c are not particularly limited as long as the leak prevention groove 67c can cut off the electric path formed by the deposit scattered when the fuse element 2 is blown and prevent the leak current.

[0065] 6(a) and 6(b), on the surface of the second case 6b facing the first case 6a, insertion hole forming surfaces 64c, 65c are provided on the outer sides of the leak prevention groove 67c in the X direction in a plan view. The two insertion hole forming surfaces 64c, 65c are disposed opposite each other in the X direction in a plan view.

[0066] 4(b), the length in the Y direction of the two insertion hole forming surfaces 64c, 65c 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. For this reason, the entire surfaces of the first end 21 and the second end 22 of the fuse element 2 in the widths 21D, 22D directions are arranged in contact with the insertion hole forming surfaces 64c, 65c. 6(b), the insertion hole forming surfaces 64c, 65c are provided at positions closer to the first wall surface 60c in the Z direction than the second joint surface 68c that is bonded to the first case 6a. As a result, steps are formed at the boundaries between the insertion hole forming surfaces 64c, 65c and the second joint surface 68c.

[0067] In the protection element 100 of this embodiment, the dimension of the step between the boundary portion of the insertion hole forming surface 64c, 65c and the second bonding surface 68c is the same as the height dimension of the top of the second protrusion 68b from the second bonding surface 68c.

[0068] 6(a) and 6(b), a terminal mounting surface 64b is provided on the outer side in the X direction of the insertion hole forming surface 64c, and a terminal mounting surface 65b is provided on the outer side in the X direction of the insertion hole forming surface 65c. 6(b), the terminal mounting surfaces 64b, 65b are provided at positions farther from the first wall surface 60c in the Z direction than the surfaces of the insertion hole forming surfaces 64c, 65c. As a result, steps are formed at the boundaries between the terminal mounting surfaces 64b, 65b and the insertion hole forming surfaces 64c, 65c.

[0069] On the surface of the second case 6b facing the first case 6a, the outer side in the Y direction of the third wall surface 60g and the fourth wall surface 60h in a plan view is a second bonding surface 68c that is bonded to the first case 6a. The second bonding surface 68c is provided along the edge of the second case 6b.

[0070] The first case 6a is a substantially rectangular parallelepiped. As shown in Fig. 3, Fig. 5(a) and Fig. 5(b), a first joint surface 68a of the first case 6a and a second joint surface 68c of the second case 6b are abutted against each other to form a storage section 60. The storage section 60 is a rectangular space in a plan view surrounded by a second convex portion 68b of the second case 6b and a first concave portion 68d of the first case 6a.

[0071] As shown in FIG. 5(a), the first recess 68d is rectangular in plan view. The planar shape of the first recess 68d of the first case 6a is the same as the planar shape of the second protrusion 68b of the second case 6b. As shown in FIG. 5(a) and FIG. 5(b), the first short side of the first recess 68d is the third wall surface 60g, the second short side is the fourth wall surface 60h, the first long side is the fifth wall surface 60e, and the second long side is the sixth wall surface 60f. The bottom surface of the first recess 68d becomes the first wall surface 60c when the first case 6a and the second case 6b are joined together.

[0072] 5(a), a leak prevention groove 67d is provided along the fifth wall surface 60e and the sixth wall surface 60f at the joint portion of the first wall surface 60c with the fifth wall surface 60e and the joint portion of the first wall surface 60c with the sixth wall surface 60f. The two leak prevention grooves 67d are arranged opposite each other in the X direction in a plan view. Like the leak prevention groove 67c provided in the first case 6a, when the molten fuse element 2 is scattered and the scattered matter adheres to the inside of the housing portion 60 when the fuse element 2 is blown, the leak prevention groove 67d cuts off the electric path formed by the adhered matter to prevent a leak current.

[0073] As shown in FIG. 4(b), the length of the leak prevention groove 67d in the Y direction is the same as the distance 60D in the Y direction between the third wall surface 60g and the fourth wall surface 60h. This makes it easy to form the leak prevention groove 67d. The length of the leak prevention groove 67d in the Y direction may be shorter than the distance 60D in the Y direction between the third wall surface 60g and the fourth wall surface 60h, but is preferably longer than the width 21D in the Y direction at the first end 21 of the fuse element 2 and the width 22D in the Y direction at the second end 22. In this case, it is possible to more effectively prevent the scattered matter attached to the inside of the housing portion 60 when the fuse element 2 melts from being electrically connected to the first terminal 61 or the second terminal 62, and to more effectively prevent the occurrence of a leak current.

[0074] 4(b), in this embodiment, the longitudinal center portion of the leak prevention groove 67d provided in the first case 6a is disposed opposite to the longitudinal center portion of the leak prevention groove 67c in the second case 6b, and the longitudinal end portion of the leak prevention groove 67d is disposed opposite to the first joint surface 68a of the first case 6a.

[0075] In the protection element 100 of this embodiment, the leak prevention groove 67d is preferably provided, but may not be provided. The leak prevention groove 67d is preferably provided along the joint portion of the first wall surface 60c with the fifth wall surface 60e and the joint portion of the first wall surface 60c with the sixth wall surface 60f, but may be provided at another position on the bottom surface of the first recess 68d, or only one of the two leak prevention grooves 67d. When the leak prevention groove 67d is provided along the joint portion of the first wall surface 60c with the fifth wall surface 60e and the joint portion of the first wall surface 60c with the sixth wall surface 60f, it is possible to effectively prevent the scattered matter attached to the inside of the housing portion 60 when the fuse element 2 melts from being electrically connected to the first terminal 61 or the second terminal 62, and to effectively prevent the formation of a new electrical path.

[0076] The leak prevention groove 67d provided in the first case 6a is formed with a substantially constant width and depth. The width of the leak prevention groove 67d provided in the first case 6a may be the same as or different from the width of the leak prevention groove 67c provided in the second case 6b. The width and depth of the leak prevention groove 67d are not particularly limited as long as the leak prevention groove 67d can cut off the electric path formed by the attached matter scattered when the fuse element 2 is blown, thereby preventing leakage.

[0077] 5(a) and 5(b), on the surface of the first case 6a facing the second case 6b, insertion hole forming surfaces 64d, 65d are provided on the outer sides of the leak prevention groove 67d in the X direction in a plan view. The two insertion hole forming surfaces 64d, 65d are disposed opposite each other in the X direction in a plan view. 5(b), the insertion hole forming surfaces 64d, 65d are provided at positions closer to the first wall surface 60c in the Z direction than the first joint surface 68a is, so that steps are formed at the boundaries between the insertion hole forming surfaces 64d, 65d and the first joint surface 68a.

[0078] 5(a) and 5(b), a terminal mounting surface 64a is provided on the outer side in the X direction of the insertion hole forming surface 64d. Also, a terminal mounting surface 65a is provided on the outer side in the X direction of the insertion hole forming surface 65d. 5(b), the terminal mounting surfaces 64a, 65a are located closer to the first joint surface 68a in the Z direction than the insertion hole forming surfaces 64d, 65d, and closer to the first wall surface 60c in the Z direction than the first joint surface 68a. As a result, steps are formed at the boundaries between the terminal mounting surfaces 64a, 65a and the insertion hole forming surfaces 64d, 65d and the first joint surface 68a.

[0079] 3, an insertion hole forming surface 64d of the first case 6a is disposed opposite an insertion hole forming surface 64c of the second case 6b to form a first insertion hole 64 that opens into the first wall surface 60c. An insertion hole forming surface 65d of the first case 6a is disposed opposite an insertion hole forming surface 65c of the second case 6b to form a second insertion hole 65 that opens into the second wall surface 60d. As shown in FIG. 3, the fuse element 2 is disposed between the insertion hole forming surface 64c and the insertion hole forming surface 64d, and between the insertion hole forming surface 65c and the insertion hole forming surface 65d. 3, the first terminal 61 is disposed between the terminal mounting surface 64b and the terminal mounting surface 64a. The second terminal 62 is disposed between the terminal mounting surface 65b and the terminal mounting surface 65a.

[0080] On the surface of the first case 6a facing the second case 6b, the outer side in the Y direction of the third wall surface 60g and the fourth wall surface 60h in a plan view is a first joint surface 68a that is fixed to the second case 6b. The first joint surface 68a is provided along the edge of the first case 6a.

[0081] The first case 6a and the second case 6b forming the case 6 are made of an insulating material such as a ceramic material or a resin material.

[0082] Examples of ceramic materials include alumina, mullite, zirconia, etc., and it is preferable to use a material with high thermal conductivity such as alumina. When the first case 6a and the second case 6b are formed 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, and the continuation of the arc discharge generated when the fuse element 2 is cut can be more effectively suppressed.

[0083] The resin material is preferably any one selected from polyphenylene sulfide (PPS) resin, nylon resin, fluorine resin such as polytetrafluoroethylene, and polyphthalamide (PPA) resin, and is particularly preferably a nylon resin.

[0084] As the nylon-based resin, an aliphatic polyamide or a semi-aromatic polyamide may be used. 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 if the first case 6a and / or the second case 6b 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 case 6a and the second case 6b using an aliphatic polyamide, it is possible to prevent the graphite generated when the fuse element 2 melts from forming a new electrical path.

[0085] 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. Among these nylon-based resins, it is preferable to use a resin that does not contain a benzene ring, such as aliphatic polyamides such as 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.

[0086] The resin material to be used preferably has a tracking resistance index CTI of 400 V or more, and more preferably 600 V or more. The tracking resistance can be determined by a test based on IEC60112. Among resin materials, nylon-based resins are particularly preferable because they have high tracking resistance (resistance to tracking (carbonized conductive path) breakdown).

[0087] 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 the resin changes from a soft rubbery state to a hard glassy state. When a resin is heated to a temperature above the glass transition temperature, the molecules become more mobile and the resin becomes soft and rubbery. On the other hand, when the resin cools, the molecular movement is restricted and the resin becomes hard and glassy.

[0088] When the first case 6a and the second case 6b 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 generated when the fuse element 2 is cut can be more effectively suppressed. The first case 6a and the second case 6b can be manufactured by a known method.

[0089] (Protective element manufacturing method) Next, a method for manufacturing the protective element 100 of this embodiment will be described with reference to an example. To manufacture the protective element 100 of this embodiment, the fuse element 2, the first terminal 61, and the second terminal 62 are prepared. Then, as shown in Fig. 4(a), the first terminal 61 is connected onto the first end 21 of the fuse element 2 by soldering. Also, the second terminal 62 is connected onto the second end 22 by soldering.

[0090] As the solder material used for soldering in this embodiment, any known solder material can be used, and it is preferable to use a solder material containing Sn as a main component from the viewpoints of resistivity, melting point, and environmental friendliness and lead-freeness. The first end 21 and the second end 22, and the first terminal 61 and the second terminal 62 of the fuse element 2 may be connected by joining through welding, and any known joining method can be used.

[0091] Next, a first case 6a shown in Figures 5(a) to 5(c) and a second case 6b shown in Figures 6(a) to 6(c) are prepared. Then, as shown in Figure 2, a member in which the fuse element 2 and the first and second terminals 61 and 62 are integrated is placed on the second case 6b. As shown in Figure 2, the member is placed such that the first terminal 61 and the second terminal 62 are located closer to the second wall surface 60d than the fuse element 2.

[0092] In this embodiment, as shown in Fig. 3, the first terminal 61 is placed on the terminal placement surface 64b, and the second terminal 62 is placed on the terminal placement surface 65b, so that the fuse element 2, the first terminal 61, and the second terminal 62 are aligned with respect to the second case 6b (see Fig. 2). As a result, the above-mentioned member is installed such that the center position of the length 2L in the X direction excluding the area overlapping the first terminal 61 and the second terminal 62 in the fuse element 2 in a plan view coincides with the center position of the length 6L in the X direction between the fifth wall surface 60e and the sixth wall surface 60f, and the center position of the length between the third wall surface 60g and the fourth wall surface 60h coincides with the center position of the fuse element 2 in the Y direction, as shown in Fig. 4(b).

[0093] Thereafter, the first case 6a and the second case 6b are joined together (see FIG. 3). An adhesive may be used to join the first case 6a and the second case 6b. For example, an adhesive containing a thermosetting resin may be used as the adhesive. The first case 6a and the second case 6b may be joined together by wrapping an adhesive tape made of a resin such as polyimide around the outer surfaces of the first case 6a and the second case 6b. The first case 6a and the second case 6b may be joined together by using both an adhesive and an adhesive tape. When joining the first case 6a and the second case 6b, the leak prevention groove 67c provided in the second case 6b and the center of the leak prevention groove 67d provided in the first case 6a are positioned so as to overlap in a plan view (see FIG. 4(b)). The first case 6a and the second case 6b may be fixed together by a cover (not shown) disposed on the outside of the case 6.

[0094] By joining the first case 6a and the second case 6b, an accommodation section 60 surrounded by the second convex portion 68b of the second case 6b and the first concave portion 68d of the first case 6a is formed in the case 6. At this time, in the protection element 100 of this embodiment, the top of the second convex portion 68b of the second case 6b (in other words, the second wall surface 60d) and the insertion hole forming surfaces 64c, 65c are disposed at a position closer to the first wall surface 60c in the Z direction than the first joining surface 68a of the first case 6a (see FIGS. 3, 5(b), and 6(b)).

[0095] Furthermore, by joining the first case 6a and the second case 6b, as shown in FIG. 3, the first end 21 of the fuse element 2 is accommodated in the first insertion hole 64, and the second end 22 of the fuse element 2 is accommodated in the second insertion hole 65, and a portion 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 (see FIG. 1). Through the above steps, the protective element 100 of this embodiment is obtained.

[0096] (Protection element operation) Next, the operation of the protection element 100 in the present embodiment when a current exceeding the rated current flows through the fuse element 2 of the protection element 100 will be described. When a current exceeding the rated current flows through the fuse element 2 of the protective device 100 of this embodiment, the fuse element 2 heats up due to the overcurrent, causing the fuse element 2 to heat up. When the fuse element 2 melts due to the temperature rise, the fuse element 2 is blown. At this time, a spark is generated between the cut surfaces of the cut portions 23, causing an arc discharge.

[0097] 3, in the protection element 100 of this embodiment, a distance H6 in the Z direction between a first wall surface 60c and a second wall surface 60d provided in the housing portion 60 of the case 6 is set to be 10 times or less the length H23 in the Z direction of the cutting portion 23 of the fuse element 2. Therefore, the amount of moving charge generated by the arc discharge is small, and the arc discharge is small in scale.

[0098] As described above, the protection element 100 of this embodiment includes a fuse element 2 having a cutting portion 23 between a first end 21 and a second end 22, and energized in a first direction (X direction) from the first end 21 to the second end 22, and a case 6 made of an insulating material and having a housing portion 60 in which the cutting portion 23 is housed. In the protection element 100 of this embodiment, the length H23 of the cutting portion 23 in the thickness direction (Z direction) in the cross section in the first direction (X direction) is equal to or less than the length in the width direction (Y direction) intersecting with the thickness direction (Z direction) in the cross section in the first direction (X direction), and the housing portion 60 is provided with a first wall surface 60c and a second wall surface 60d made of flat surfaces facing each other in the Z direction, and the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d is equal to or less than 10 times the length H23 of the cutting portion 23 in the Z direction. This provides the following effects.

[0099] That is, in the protective element 100 of this embodiment, the arc discharge that occurs when the fuse element 2 melts is small-scale. Therefore, in the protective element 100 of this embodiment, the accommodating portion 60 can be prevented from being destroyed due to a pressure increase in the accommodating portion 60, and the protective element 100 of this embodiment is excellent in safety. In addition, the protective element 100 of this embodiment can be preferably installed in a current path of a high voltage of 100 V or more and a large current of 100 A or more, for example.

[0100] In addition, the protection element 100 of this embodiment can be made smaller because the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d is short. Furthermore, in the protection element 100 of this embodiment, the arc discharge is small-scale, so the thickness between the housing portion 60 and the outer surface of the case 6 can be made thinner, thereby making the protection element 100 smaller. Therefore, according to the protection element 100 of this embodiment, the amount of material used for the case 6 can be reduced.

[0101] Moreover, in the protection element 100 of this embodiment, the entire surface 23b of the cutting portion 23 of the fuse element 2 on the second wall surface 60d side is arranged in contact with the second wall surface 60d. Therefore, in the protection element 100 of this embodiment, the number of electric field lines on the surface 23b of the cutting portion 23 on the second wall surface 60d side generated by the arc discharge is reduced, and the heat generated when the fuse element 2 is cut can be efficiently dissipated to the outside via the second wall surface 60d. Therefore, the arc discharge generated when the fuse element 2 melts is smaller. Moreover, when the entire surface 23b of the cutting portion 23 on the second wall surface 60d side is arranged in contact with the second wall surface 60d, the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d can be further shortened, making it possible to further reduce the size.

[0102] 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 composed of Sn and an outer layer made of Ag or Cu or a metal mainly composed of Ag or Cu are laminated in the thickness direction, and the case 6 is made of a resin material. In such a protection device, the arc discharge generated when the fuse element 2 melts is further reduced in scale and further miniaturization is possible for the reasons described below.

[0103] That is, when the fuse element 2 is made of the laminate, the melting temperature of the fuse element 2 is low, for example, 300 to 400°C. Therefore, even if the case 6 is made of a resin material, sufficient heat resistance can be obtained. In addition, since the melting temperature of the fuse element 2 is low, even if the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d in the housing portion 60 is 10 times or less the length H23 in the Z direction of the cutting portion 23, and further, even if the first wall surface 60c and / or the second wall surface 60d are arranged in contact with the cutting portion 23 of the fuse element 2, the fuse element 2 reaches the melting temperature in a short time. Therefore, the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d in the housing portion 60 can be sufficiently short without impairing the function of the fuse element 2.

[0104] Moreover, in such a protection element, the heat accompanying the melting of the fuse element 2 decomposes the resin material forming the case 6, generating pyrolysis gas, and the heat of vaporization cools the inside of the housing portion 60 (resin ablation effect). 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 case 6 is made of a resin material, the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d in the housing portion 60 can be shortened to further reduce the arc discharge and further reduce the size of the device.

[0105] 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), polyethylene terephthalate (PET), etc. From the viewpoints of heat resistance and flame retardancy, it is preferable to use nylon 46 or nylon 66 as the resin material forming the case.

[0106] The ablation effect of the resin is more effectively obtained when the distance 60D in the Y direction between the third wall surface 60g and the fourth wall surface 60h in the accommodating portion 60 (see FIG. 4(b)) is 1.5 times or more the length in the Y direction (widths 21D, 22D) of the fuse element 2. This is presumably because, even if the distance 60D in the Y direction in the accommodating portion 60 is increased, there is little effect on the number of electric field lines generated by the arc discharge, but the surface area in the accommodating portion 60 increases significantly, and the decomposition of the resin material is promoted by the heat accompanying the melting of the fuse element 2.

[0107] In contrast, for example, a protection element having a fuse element made of Cu and a case made of a ceramic material may be difficult to miniaturize for the following reasons. That is, when the fuse element is made of Cu, the melting temperature of the fuse element is high, at 1000°C or more. 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.

[0108] In this protective element, the fuse element has a high melting temperature and the case is made of a ceramic material, so if the distance between the cutoff part of the fuse element and the inner surface of the case is made short, the heat generated at the cutoff part is dissipated through the case, making it difficult for the fuse element to reach the melting temperature. For this reason, it is necessary to ensure a sufficient distance between the cutoff part and the inner surface of the case. Therefore, in a protective element in which the fuse element is made of Cu and the case is made of a ceramic material, a large storage space must be provided inside the case.

[0109] Furthermore, if a sufficient distance is ensured between the cut portion and the inner surface of the case, the number of electric field lines generated by the arc discharge increases, and the arc discharge generated when the fuse element melts becomes large. For this reason, it may become necessary to put an arc-extinguishing agent in a storage section within the case in order to quickly extinguish (extinguish) the arc discharge. When putting an arc-extinguishing agent in the case, it is necessary to secure a space within the case to store the arc-extinguishing agent. This may require a larger storage section to be provided within the case, which may make it even more difficult to make the fuse even smaller.

[0110] [Second embodiment] FIG. 7 is a cross-sectional view for explaining a protection element 200 according to the second embodiment, and is a cross-sectional view corresponding to a position where the protection element 100 according to the first embodiment is cut along the line AA' shown in FIG. 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.

[0111] The protection element 200 of the second embodiment differs from the protection element 100 of the first embodiment in that not only is a space 60a provided between the fuse element 2 and the first wall surface 60c, but a space 60b is also provided between the fuse element 2 and the second wall surface 60d.

[0112] As shown in FIG. 7, within the accommodation portion 60 of the protection element 200 of this embodiment, a first wall surface 60c and a second wall surface 60d made of flat surfaces facing each other in the thickness direction (Z direction) of the cut portion 23 are provided. In the protection element 200 of this embodiment, similarly to the protection element 100 of the first embodiment, the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d is set to be 10 times or less the Z-direction length H23 of the cut portion 23. In the protection element 200 of this embodiment, too, the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d is preferably 5 times or less the Z-direction length H23 of the cut portion 23, and more preferably 2 times or less.

[0113] 7, in the protection element 200 of this embodiment, the distance H6a between the fuse element 2 and the first wall surface 60c and the distance H6b between the fuse element 2 and the second wall surface 60d are substantially the same. The distance H6a between the fuse element 2 and the first wall surface 60c and the distance H6b between the fuse element 2 and the second wall surface 60d may be different, and either the distance H6a or the distance H6b may be longer.

[0114] In the protection element 200 of this embodiment, as shown in Fig. 7, a space 60b is provided between the fuse element 2 and the second wall surface 60d. Therefore, instead of the second convex portion 68b (see Fig. 3) provided on the second case 6b in the protection element 100 according to the first embodiment, the protection element 200 of this embodiment has a second concave portion 68e shown in Fig. 7. The second recess 68e has a rectangular planar shape, which is the same as the planar shape of the first recess 68d of the first case 6a and the second protrusion 68b shown in FIGS. 6(a) and 6(b).

[0115] The second recess 68e has a first short side that is the third wall surface 60g, a second short side that is the fourth wall surface 60h, and a first long side that is the fifth wall surface 60e and a second long side that is the sixth wall surface 60f as shown in Fig. 7. The bottom surface of the second recess 68e becomes the second wall surface 60d when the first case 6a and the second case 6b are joined together as shown in Fig. 7. The depth of the second recess 68e is a dimension corresponding to the distance H6b between the fuse element 2 and the second wall surface 60d.

[0116] The protection element 200 of this embodiment can be manufactured in the same manner as the protection element 100 of the first embodiment, except that the second case 6b has a second recess 68e shown in Figure 7 instead of the second convex portion 68b shown in Figures 6(a) and 6(b).

[0117] In the protection element 200 of this embodiment, similarly to the protection element 100 of the first embodiment, the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d provided in the housing portion 60 of the case 6 is set to be 10 times or less the length H23 in the Z direction of the cutting portion 23 of the fuse element 2. Therefore, in the protection element 200 of this embodiment, similarly to the protection element 100 of the first embodiment, the arc discharge generated when the fuse element 2 melts is small and the protection element 200 can be made compact.

[0118] [Other examples] The protection element of the present invention is not limited to the protection elements of the first and second embodiments described above. For example, in the protection element 100 of the first embodiment described above, as shown in Figure 3, a space 60a is provided between the fuse element 2 and the first wall surface 60c, and the entire surface 23b of the fuse element 2 facing the second wall surface 60d at the cutting portion 23 is arranged in contact with the second wall surface 60d. However, the protection element of the present invention may be one in which a space is provided between the fuse element 2 and the second wall surface 60d shown in Figure 3, and the surface of the cutting portion 23 facing the first wall surface 60c is arranged in contact with the first wall surface 60c.

[0119] In addition, the protection element of the present invention may be one in which the surface 23b of the cutting portion 23 on the second wall surface 60d side is disposed in contact with the second wall surface 60d, and the surface of the cutting portion 23 on the first wall surface 60c side is disposed in contact with the first wall surface 60c, as shown in FIG. 3. In this case, the number of electric field lines on the surface 23b of the cutting portion 23 on the second wall surface 60d side caused by the arc discharge is reduced, and the number of electric field lines on the surface 23b of the cutting portion 23 on the first wall surface 60c side caused by the arc discharge is also reduced. Moreover, the heat generated when the fuse element 2 is cut is efficiently dissipated to the outside via the second wall surface 60d and the first wall surface 60c. As a result, the arc discharge generated when the fuse element 2 is melted is smaller in scale. Moreover, since the surface 23b of the cutting portion 23 facing the second wall surface 60d and the surface facing the first wall surface 60c are disposed in contact with the inner surface of the accommodation portion 60, the distance H6 in the thickness direction (Z direction) between the first wall surface 60c and the second wall surface 60d becomes the shortest. Therefore, in such a protection element, the arc discharge generated when the fuse element 2 melts becomes even smaller, and the protection element can be made even more compact.

[0120] Furthermore, the protection element of the present invention may include a shielding mechanism as necessary. For example, the shielding mechanism may be a slider part having an opening through which the fuse element is disposed. When blown, the slider part moves in the Z direction perpendicular to the current flow direction of the fuse element to physically block the first insertion hole. This insulates the cut surfaces of the blown fuse element from each other, and the arc discharge that occurs when the fuse element blows is quickly extinguished (extinguished). EXAMPLES

[0121] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0122] Example 1 The protective element 100 of Example 1 shown in FIG. 1 was manufactured by the method described below. The fuse element 2 prepared had a resistance of 0.5 mΩ and had the following dimensions and materials: Width of fuse element 2 (distance 21D, 22D in Y direction): 6.5 mm Width of the cut portion 23 (distance 23D in the Y direction): about 5.4 mm Thickness of the cut portion 23 (distance H23 in the Z direction): 0.2 mm Material: A laminate in which an inner layer made of an alloy mainly composed of Sn is entirely coated on both sides with an outer layer made of Ag plating with a minimum thickness of 10 μm, with the outer layer, inner layer and outer layer stacked in that order in the thickness direction.

[0123] The first terminal 61 and the second terminal 62 were made of Cu. Then, the first terminal 61 was soldered onto the first end 21 of the fuse element 2, and the second terminal 62 was soldered onto the second end 22, and integrated. The length 2L of the fuse element 2 in the X direction excluding the area overlapping the first terminal 61 and the second terminal 62 in a plan view was set to 9.5 mm.

[0124] The case 6 was prepared as a rectangular parallelepiped with an external shape of 16.8 mm in length (length in the X direction), 18.0 mm in width (length in the Y direction), and 10 mm in height (length in the Z direction) when the first case 6a and the second case 6b were joined together. Nylon 66 (product name: N66 (NC), manufactured by Toray Industries, Inc.) was used as the material for the case 6.

[0125] By setting the depth of the first recess 68d of the first case 6a to 1.0 mm and the height of the second protrusion 68b of the second case 6b to 0.25 mm, the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d within the storage section 60 is set to 0.75 mm. In addition, the distance 60D in the width direction (Y direction) of the cut portion 23 between the third wall surface 60g and the fourth wall surface 60h within the storage portion 60 is 14 mm, and the length 6L in the X direction between the fifth wall surface 60e and the sixth wall surface 60f within the storage portion 60 is 8.0 mm.

[0126] Next, a member in which the fuse element 2, the first terminal 61 and the second terminal 62 were integrated was placed on the second case 6b. At this time, the fuse element 2 is installed so that the center position of the length 2L in the X direction excluding the area overlapping with the first terminal 61 and the second terminal 62 in a planar view coincides with the center position of the length 6L in the X direction between the fifth wall surface 60e and the sixth wall surface 60f, and the center position of the length between the third wall surface 60g and the fourth wall surface 60h coincides with the center position of the fuse element 2 in the Y direction.

[0127] Thereafter, the first case 6a was placed on top of the component in which the fuse element 2 and the first terminal 61 and second terminal 62 were integrated, and the first case 6a and the second case 6b were joined together by wrapping an adhesive tape made of polyimide around the outer surfaces of the first case 6a and the second case 6b. Through the above steps, the protective element of Example 1 was obtained.

[0128] Example 2 The protection element of Example 2 was obtained in the same manner as Example 1, except that the depth of the first recess 68d of the first case 6a was 0.5 mm and the height of the second protrusion 68b of the second case 6b was 0.25 mm, so that the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d was 0.25 mm (1.25 times the thickness of the cut portion (0.2 mm)).

[0129] Example 3 The protection element of Example 3 was obtained in the same manner as Example 1, except that the depth of the first recess 68d of the first case 6a was 2.0 mm and the height of the second protrusion 68b of the second case 6b was 0.25 mm, so that the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d was 1.75 mm (8.75 times the thickness of the cut portion (0.2 mm)).

[0130] Example 4 The protection element of Example 4 was obtained in the same manner as Example 1, except that the depth of the first recess 68d of the first case 6a was set to 1.0 mm, and a second case 6b was used in which a second recess 68e with a depth of 0.5 mm was provided instead of the second protrusion 68b, so that the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d was 1.5 mm (7.5 times the thickness of the cut portion (0.2 mm)).

[0131] Example 5 The protection element of Example 5 was obtained in the same manner as Example 1, except that the depth of the first recess 68d of the first case 6a was set to 1.0 mm, and a second case 6b was used in which a second recess 68e having a depth of 1.0 mm was provided instead of the second protrusion 68b, so that the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d was 2.0 mm (10 times the thickness of the cut portion (0.2 mm)).

[0132] Comparative Example 1 A protective element of Comparative Example 1 was obtained in the same manner as in Example 1, except that the depth of the first recess 68d of the first case 6a was set to 2.0 mm, and a second case 6b was used in which a second recess 68e having a depth of 2.0 mm was provided instead of the second protrusion 68b, so that the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d was 4.0 mm (20 times the thickness of the cut portion (0.2 mm)).

[0133] The thus obtained protective elements of Examples 1 to 5 and Comparative Example 1 were placed in a current path with a voltage of 150 V and a current of 2000 A, and a current interruption was performed. Then, the protective elements of Examples 1 to 5 and Comparative Example 1 were measured and evaluated for the following items. Fig. 13 is a diagram showing the measurement results of the protection elements of Examples 1 to 3 and the evaluation results when they were interrupted at a voltage of 150 V and a current of 2000 A. Fig. 14 is a diagram showing the measurement results of the protection elements of Examples 4, 5, and Comparative Example 1 and the evaluation results when they were interrupted at a voltage of 150 V and a current of 2000 A.

[0134] (Space height) From the depth dimension of the first recess 68d in the first case 6a and the height dimension of the second protrusion 68b or the depth dimension of the second recess 68e in the second case 6b, the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d in the storage section 60 was calculated as the spatial height.

[0135] (Shutdown time) Using a current probe capable of measuring currents of 2000A or more, the time from when the current started to when it was cut off was measured. (Fusing length) The length in the X direction of the member in which the fuse element 2, the first terminal 61, and the second terminal 62 were integrated and which melted when the current was interrupted was measured and taken as the melting length. The arrows drawn on the upper surface of the X-ray after the test indicate the melting length. In the protection elements of Example 1, Examples 3 to 5, and Comparative Example 1, not only the fuse element 2 but also the first terminal 61 and the second terminal 62 melted when the current was interrupted.

[0136] (X-ray top view before test) 13 is an X-ray photograph taken by an X-ray imaging device of the protection elements of Examples 1 to 5 and Comparative Example 1 from the first case 6a side before current is supplied. (X-ray side view before test) The X-ray photographs were taken using the above-mentioned X-ray imaging device, looking from the Y direction, of the protection elements of Examples 1 to 5 and Comparative Example 1 before current was supplied. The light gray parts in the photographs are spaces, and the dark gray parts are cases. The black part across the center of the photograph is a member in which the fuse element 2 is integrated with the first terminal 61 and the second terminal 62. (X-ray top view after test) 13 is an X-ray photograph taken by using the above-mentioned X-ray imaging device of the protection elements of Examples 1 to 5 and Comparative Example 1 from the first case 6a side after current interruption.

[0137] (When shut off) Photographs showing arc discharge in the protection elements of Examples 1 to 4. For the protection elements of Example 5 and Comparative Example 1, the photographs were pure white due to light caused by arc discharge. (judgement) The evaluation was based on the following criteria. ⊚: Only the fuse element melted. ○: In addition to the fuse element, the first and second terminals were melted, but parts of the flanges of the first and second terminals remained unmelted. △: In addition to the fuse element, the flanges of the first and second terminals were melted, but parts of the first and second terminals remained inside the case. ×: In addition to the fuse element, the first terminal and the second terminal melted to the outside of the case.

[0138] As shown in the pre-test X-ray top photographs in FIGS. 13 and 14, no difference was observed in the X-ray photographs taken from the first case 6a side for the protection elements of Examples 1 to 5 and Comparative Example 1. As shown in the pre-test X-ray side photograph in Fig. 13, in the protection elements of Examples 2 and 3, the entire surface of the cut portion 23 of the fuse element 2 facing the second wall surface 60d is disposed in contact with the second wall surface 60d. Also, as shown in the pre-test X-ray side photograph in Fig. 13, in the protection element of Example 2, the surface of the cut portion 23 facing the second wall surface 60d is disposed in contact with the second wall surface 60d, and the surface of the cut portion 23 facing the first wall surface 60c is disposed in contact with the first wall surface 60c.

[0139] 13, in the protection element of Example 2, as shown in the X-ray top view photograph after the test, only the fuse element 2 melted, and the current was interrupted without melting the first terminal 61 and the second terminal 62. Moreover, in the protection elements of Examples 1 to 3, as shown in the photograph during current interruption, the arc discharge generated when the fuse element 2 fused was small in scale. Moreover, from the results of the protection elements of Examples 1 to 3, it was confirmed that the lower the spatial height, the shorter the interruption time and interruption length, and the smaller the scale of the arc discharge.

[0140] Furthermore, as shown in the pre-test X-ray side photograph in Figure 14, in the protection elements of Example 4, Example 5, and Comparative Example 1, a space is provided between the fuse element 2 and the first wall surface 60c, and between the fuse element 2 and the second wall surface 60d.

[0141] As shown in Figure 14, in the protective elements of Examples 4 and 5, as shown in the X-ray top view photograph after the test, the fuse element 2 and the flanges of the first terminal 61 and the second terminal 62 melted, but parts of the first terminal 61 and the second terminal 62 did not melt and remained inside the case. In contrast to this, in Comparative Example 1, the fuse element 2 melted, and further the first terminal and the second terminal melted to the outside of the case, and the arc discharge was large-scale compared to Examples 1 to 5. Furthermore, as shown in FIG. 14, in the protection elements of Example 4, Example 5, and Comparative Example 1, it was confirmed that the lower the spatial height, the shorter the interruption time and the smaller the scale of the arc discharge, as in the protection elements of Examples 1 to 3.

[0142] The protection elements of Examples 1, 3, and 4 have a length 2L of 9.5 mm in the X direction excluding the area overlapping with the first terminal 61 and the second terminal 62 of the fuse element 2 in a plan view. Since the arc discharge was relatively small in the protection elements of Examples 1, 3, and 4, it is presumed that melting of the first terminal 61 and the second terminal 62 can be suppressed by making the length 2L longer than 9.5 mm.

[0143] In addition, the protection element of Example 3 (spatial height 1.75 mm) has a higher spatial height than the protection element of Example 4 (spatial height 1.5 mm), but the interruption time and interruption length were shorter than those of the protection element of Example 4. This is believed to be because the protective element of Example 3 is positioned so that the entire surface of the fuse element 2 facing the second wall surface 60d at the cutting portion 23 is in contact with the second wall surface 60d, thereby further suppressing arc discharge.

[0144] Therefore, in the protective element of Example 5, as in Example 3, by arranging the entire surface of the cutting portion 23 of the fuse element 2 facing the second wall surface 60d in contact with the second wall surface 60d, it is estimated that arc discharge can be suppressed to a small scale even with a spatial height of 2.0 mm (10 times the thickness direction length of the fuse element 2).

[0145] (Protection element A) A protection element A according to an embodiment of the present invention was fabricated that was the same as the protection element of the embodiment 1, except that a shielding mechanism was added to the cut portion 23. The protection device A includes a slider component having an opening through which the fuse element is disposed as a shielding mechanism. The slider component moves in the Z direction perpendicular to the current flow direction of the fuse element when blown, and physically blocks the first insertion hole. FIG. 8 is a photograph showing the state in which the fuse element used in protection device A, the first terminal, and the second terminal integrated together, are placed on the second case together with the slider part. The fuse element is integrated with the first terminal and the second terminal while passing through the opening of the slider component.

[0146] (Protection element B) A protection element B, which is a comparative example of the present invention, was obtained in the same manner as in Example 1, except that the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d in the storage portion 60 was 14 mm, the widthwise (Y-direction) distance 60D of the cut portion 23 between the third wall surface 60g and the fourth wall surface 60h was 24.6 mm, and the X-direction length 6L between the fifth wall surface 60e and the sixth wall surface 60f in the storage portion 60 was 13.6 mm.

[0147] The protective element A and protective element B thus obtained were placed in a current path with a voltage of 150 V and a current of 190 A, and a current interruption was performed. Fig. 9 is a photograph of an arc discharge when protective element B, which is a comparative example, is interrupted at a voltage of 150 V and a current of 190 A. Fig. 10 is a photograph taken of the state of protective element B, which is a comparative example, after current interruption. Fig. 11 is a photograph of an arc discharge when protection element A of the embodiment is interrupted at a voltage of 150 V and a current of 190 A. Fig. 12 is a photograph taken of the state of protection element A of the embodiment after current interruption.

[0148] As shown in Fig. 9, in the protection element B in which the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d was set to 14 mm (70 times the thickness (0.2 mm) of the cut portion 23), a large-scale arc discharge occurred, and sparks were emitted from the protection element together with an explosion sound. Also, as shown in Fig. 10, in the protection element B, the fuse element 2 and the first terminal 61 and the second terminal 62 electrically connected to both ends of the fuse element 2, respectively, melted.

[0149] On the other hand, as shown in FIG. 11, in the protection element A in which the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d is 0.75 mm (3.75 times the thickness of the cut portion (0.2 mm)), the arc discharge was small-scale compared to the protection element B. Also, as shown in FIG. 12, in the protection element A, the fuse element 2 melted only partially, thereby interrupting the current. Also, in the protection element A, the insulation resistance was 1.36×10 12 It was Ω and was good. [Explanation of symbols]

[0150] 2 Fuse elements 4. Electric Field Lines 6 Cases 6a Case 1 6b Case 2 21 First end 22 Second end 23 Cut section 25 1st connection part 26 2nd connection part 60 Storage unit 60a, 60b space 60c 1st wall 60d 2nd wall 60e 5th wall 60th floor, 6th wall 60g 3rd wall 60h 4th wall 61 1st terminal 61a, 62a External terminal holes 61c, 62c Tsubabe 62 2nd terminal 64 First insertion hole 64a, 64b, 65a, 65b Terminal mounting surface 64c, 64d, 65c, 65d Insertion hole forming surface 65 Second insertion hole 67c, 67d Leak prevention groove 68a 1st joint surface 68b Second convex part 68c 2nd joint surface 68d First recess 68e Second recess 100, 200 Protection element

Claims

1. a fuse element having a cut portion between a first end and a second end, the fuse element being energized in a first direction from the first end to the second end; a case made of an insulating material and having a housing portion therein for housing the cutting portion, a length in a thickness direction in the first direction cross section of the cut portion is equal to or less than a length in a width direction intersecting with the thickness direction in the first direction cross section, A first wall surface and a second wall surface opposed to each other in the thickness direction are provided in the storage portion, A distance in the thickness direction between the first wall surface and the second wall surface is 10 times or less the length of the cut portion in the thickness direction, The cutting portion is disposed in contact with one or both of the first wall surface and the second wall surface, A third wall surface and a fourth wall surface opposed to each other in the width direction are provided within the storage portion, A protective element in which the case is made of a resin material having a tracking resistance index CTI of 400V or more.

2. The protection element according to claim 1 , wherein a distance in the thickness direction between the first wall surface and the second wall surface is equal to or less than five times a length in the thickness direction of the cut portion.

3. The protection element according to claim 1 , wherein a distance in the thickness direction between the first wall surface and the second wall surface is equal to or smaller than twice a length in the thickness direction of the cut portion.

4. 4. The protection element according to claim 1, wherein the fuse element is in the form of a flat plate or a wire.

5. The protection element according to any one of claims 1 to 4, wherein the first end is electrically connected to a first terminal, and the second end is electrically connected to a second terminal.

6. The protection element according to any one of claims 1 to 5, wherein the melting temperature of the fuse element is 600°C or lower.

7. The protection element according to any one of claims 1 to 5, wherein the melting temperature of the fuse element is 400°C or lower.

8. 8. 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 a thickness direction.

9. The low melting point metal is made of Sn or a metal containing Sn as a main component, 9. The protective element according to claim 8, wherein the high melting point metal is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

10. 10. The protective element according to claim 1, wherein the case is made of a resin material having a tracking resistance index CTI of 600V or more.

11. 11. The protective element according to claim 1, wherein the case is made of any one selected from the group consisting of nylon resin, fluorine resin, and polyphthalamide resin.

12. 12. The protective element according to claim 11, wherein the nylon resin is a resin that does not contain a benzene ring.

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