Protective 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 Art

[0002] Conventionally, there has been a fuse element that generates heat and melts to cut off the current path when a current exceeding the rating flows through the current path. A protection element (fuse element) including a fuse element is used in a wide range of fields such as electric vehicles.

[0003] For example, Patent Document 1 describes a fuse element mainly used for an electric circuit for automobiles and the like. Patent Document 1 describes a fuse element including two elements connected between terminal portions located at both ends and a fusing portion provided at a substantially central portion of the element. Patent Document 1 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 element and the casing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a protection element installed in a current path with a high voltage and a large current, when the fuse element is melted, an arc discharge is likely to occur. When a large-scale arc discharge occurs, the case in which the fuse element is housed may be damaged. For this reason, in the conventional technology, as the voltage of the current path where the protection element is installed becomes higher and the current becomes larger, a protection element in which the fuse element is housed in a large case is used.

[0006] However, the larger the case for housing the fuse element becomes, the more material is required for the case. Also, in the protective element, miniaturization and weight reduction are required. The present invention has been made in view of the above circumstances, and an object thereof is to provide a protective element that can be miniaturized and in which the arc discharge generated when the fuse element melts is small-scale.

Means for Solving the Problems

[0007] In order to solve the above problems and obtain a small protective element in which the arc discharge generated when the fuse element melts is small-scale, the present inventors focused on the size of the accommodating portion in the case in which the cutting portion of the fuse element is accommodated, and conducted intensive studies as follows. That is, as will be described later, a protective element A was manufactured in which a fuse element having a thickness of 0.2 mm and a width of 6.5 mm was installed in the accommodating portion of the case, and the distance in the thickness direction of the fuse element in the accommodating portion was 0.75 mm. The protective element A was installed in a current path with a voltage of 150 V and a current of 190 A to cut off the current.

[0008] Also, a protective element B was manufactured which was provided with the same fuse element as the protective element A and in which the distance in the thickness direction of the fuse element in the accommodating portion of the case was 14 mm. The protective element B was installed in a current path with a voltage of 150 V and a current of 190 A to cut off the current. As a result, a large-scale arc discharge occurred in the protective element B. On the other hand, in the protective element of the protective element A, the arc discharge was very small-scale compared to the protective element B. This is presumed to be due to the reasons shown below.

[0009] FIG. 15 is a drawing for explaining the electric field line density of the cutting portion of the fuse element in the protective element A. FIG. 16 is a drawing for explaining the electric field line density of the cutting portion of the fuse element in the protective element B. In FIGS. 15 and 16, reference numeral 2 indicates a fuse element, reference numeral 61 indicates a first terminal, and reference numeral 62 indicates a second terminal. Reference numeral 6 indicates a case. Reference numeral 4 indicates electric lines of force. The electric lines of force are lines representing that Q / ε "lines" of charge come out from a charge of Q "C" and Q / ε "lines" of charge enter a charge of -Q "C".

[0010] In protection element A and protection element B, since the fuse elements are the same and the voltages and currents at the time of interruption are the same, the density of the electric lines of force generated by the arc discharge is the same. Therefore, as shown in FIGS. 15 and 16, it is presumed that the greater the distance in the thickness direction of the fuse element within the accommodating portion of the case 6, the greater the number of the electric lines of force 4, and the shorter the distance, the smaller the number of the electric lines of force 4. That is, since the charges (hot electrons) have the same polarity (negative) and repel each other, under the same discharge conditions, the interval between the charges (the density of the electric lines of force) is the same regardless of the above distance. From this, it is presumed that when the above distance is long, the amount of moving charges increases and the arc discharge becomes large-scale, and when the above distance is short, the amount of moving charges decreases and the arc discharge becomes small-scale.

[0011] Furthermore, based on the above findings, the inventors of the present invention focused on the relationship between the distance in the thickness direction of the cutting portion of the fuse element within the accommodating portion of the case and the thickness of the cutting portion, and conducted intensive studies. As a result, it was confirmed that the distance in the thickness direction of the cutting portion within the accommodating portion of the case may be set to 10 times or less the thickness of the cutting portion.

[0012] In addition, the inventors of the present invention conducted intensive studies based on the above findings, and in a protection element in which the distance in the thickness direction of the cutting portion within the accommodating portion of the case is set to 10 times or less the thickness of the cutting portion, it was found that the arc discharge becomes small-scale by arranging at least one of the wall surfaces in the thickness direction of the fuse element within the accommodating portion of the case in contact with the cutting portion. This is presumably because when the cutting portion in contact with the inside of the accommodating portion of the case is blown, the number of the electric lines of force generated by the arc discharge decreases and the fuse element is cooled.

[0013] Furthermore, the inventors focused on the relationship between the distance in the width direction of the fuse element in the housing portion of the case and arc discharge in a protective element in which the distance in the thickness direction of the cutting portion in the housing portion of the case is set to 10 times or less the thickness of the cutting portion, and conducted repeated studies. As a result, it was found that the longer the distance in the width direction of the fuse element in the housing portion of the case, the more the arc discharge is suppressed and becomes small-scale. This is presumably because when the distance in the thickness direction of the cutting portion in the housing portion of the case is the same, increasing the distance in the width direction of the fuse element in the housing portion of the case suppresses the pressure increase in the housing portion during the fusing of the fuse element, and an effect of suppressing the increase in the electric line of force density generated by the arc discharge is obtained.

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

[0015] [1] A fuse element having a cutting portion between a first end portion and a second end portion and being energized in a first direction from the first end portion toward the second end portion, a case made of an insulating material and provided with a housing portion inside which the cutting portion is housed, wherein a length in the thickness direction in a cross-section in the first direction of the cutting portion is equal to or less than a length in a width direction intersecting the thickness direction in the cross-section in the first direction, a first wall surface and a second wall surface facing each other in the thickness direction are provided in the housing portion, a protective element in which a 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 cutting portion.

[0016] [2] The protective 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 cutting portion. [3] The protection element according to [1], wherein a distance in the thickness direction between the first wall surface and the second wall surface is not more than twice a 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] In the accommodating portion, a third wall surface and a fourth wall surface facing each other in the width direction are provided, The protection element according to any one of [1] to [4], wherein a distance in the width direction between the third wall surface and the fourth wall surface is not less than 1.5 times a length in the width direction of the fuse element. [6] The protection element according to [5], wherein a distance in the width direction between the third wall surface and the fourth wall surface is from 2 times to 5 times a 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 in a flat plate shape or a linear shape. [8] The protection element according to any one of [1] to [7], wherein the first end portion is electrically connected to a first terminal, and the second end portion is electrically connected to a second terminal.

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

[10] The protection element according to any one of [1] to [8], wherein a 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 containing Sn as a main component, 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

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

BEST MODE FOR CARRYING OUT THE INVENTION

[0024] Hereinafter, this embodiment will be described in detail with appropriate reference to the drawings. The drawings used in the following description may show the characteristic parts enlarged for convenience of understanding the characteristics, and the dimensional ratios of the respective components may be different from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and can be appropriately modified and implemented within the scope where the effects of the present invention can be obtained.

[0025] [First Embodiment] (Protection Element) FIGS. 1 to 3 are schematic views showing the protection element according to the first embodiment. In the drawings used in the following description, the direction indicated by X is the current-carrying direction (first direction) of the fuse element. The direction indicated by Y is a direction orthogonal to the X direction (first direction), and the direction indicated by Z is a direction orthogonal to the X direction and the Y direction.

[0026] FIG. 1 is a perspective view showing the overall structure of the protection element 100 according to the first embodiment. FIG. 2 is an exploded perspective view showing the overall structure of the protection element 100 shown in FIG. 1. FIG. 3 is a cross-sectional view of the protection element 100 according to the first embodiment cut along the line A-A' 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 provided therein with a housing portion 60 for housing the cut portion 23 of the fuse element 2.

[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 a fuse element, a first terminal, and a 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] As shown in FIG. 4(a), the fuse element 2 is in a flat plate shape and has a first end portion 21, a second end portion 22, and a cut portion 23 provided between the first end portion 21 and the second end portion 22. The fuse element 2 is energized in the X direction (first direction), which is the direction from the first end portion 21 toward the second end portion 22. As shown in FIGS. 3 and 4(a), the first end portion 21 is electrically connected to the first terminal 61. The second end portion 22 is electrically connected to the second terminal 62.

[0029] The first terminal 61 and the second terminal 62 may be substantially the same shape or may have different shapes as shown in FIGS. 1 to 3 and FIG. 4(a). The thicknesses of the first terminal 61 and the second terminal 62 are not particularly limited, but for example, they can be set to 0.3 to 1.0 mm. The thickness of the first terminal 61 and the thickness of the second terminal 62 may be the same or different as shown in FIG. 3. As shown in FIGS. 1 to 4(a), the first terminal 61 includes an external terminal hole 61a. Also, the second terminal 62 includes an external terminal hole 62a. One of the external terminal hole 61a and the external terminal hole 62a is used for connection to the power supply side, and the other is used for connection to the load side. The external terminal hole 61a and the external terminal hole 62a can be through holes that are substantially circular in plan view as shown in FIGS. 1 to 4(a).

[0030] As the first terminal 61 and the second terminal 62, for example, those made of copper, brass, nickel, etc. can be used. From the viewpoint of enhancing rigidity, it is preferable to use brass as the material of 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 shapes of the first terminal 61 and the second terminal 62 may be any shape that can engage with the terminal on the power supply side or the load side (not shown), for example, a claw shape with an open part in a part, or as shown in Fig. 4(a), at the end on the side connected to the fuse element 2, there may be flange portions (indicated by reference numerals 61c and 62c in Fig. 4(a).) that are widened on both sides toward the fuse element 2, and it is not particularly limited. When the first terminal 61 and the second terminal 62 have the flange portions 61c and 62c, it is difficult for the first terminal 61 and the second terminal 62 to come out of the case 6, and the protection element 100 has good reliability and durability.

[0032] The fuse element 2 shown in Fig. 3 has a uniform thickness (the length in the Z direction, indicated by reference numeral H23 in Fig. 3). The thickness of the fuse element 2 may be uniform as shown in Fig. 3 or may be partially different. Examples of the fuse element with a partially different thickness include those in which the thickness gradually increases from the cut portion 23 toward the first end portion 21 and the second end portion 22. In such a fuse element 2, when an overcurrent flows, the cut portion 23 becomes a heat spot, the cut portion 23 preferentially heats up and softens, and is more surely cut.

[0033] As shown in FIG. 4(a), the planar shape of the entire fuse element 2 is substantially rectangular. 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 the present embodiment, since the arc discharge generated during the fusing of the fuse element 2 is small, the arc discharge is quickly extinguished (arc extinction). For this reason, 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 widened and the length 2L in the X direction can be shortened. The protection element 100 having such a fuse element 2 can suppress an increase in the resistance value in the current path where the protection element 100 is installed. Therefore, the protection element 100 of the present 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 substantially rectangular shape in plan view. As shown in FIG. 4(a), the width 21D in the Y direction at the first end portion 21 and the width 22D in the Y direction at the second end portion 22 are substantially 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 portion 21 and the second end portion 22.

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

[0036] In this embodiment, as an example of the fuse element 2, the length in the X direction at the second end portion 22 is longer than the length in the X direction at the first end portion 21. However, the length in the X direction at the first end portion 21 and the length in the X direction at the second end portion 22 may be the same. In other words, in this embodiment, the cutting portion 23 is arranged closer to the first terminal 61 side from the center in the X direction of the fuse element 2. However, the cutting portion 23 may be arranged at the center in the X direction of the fuse element 2.

[0037] As shown in FIG. 4(a), a first connecting portion 25 having a substantially trapezoidal shape in plan view is arranged 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. Also, a second connecting portion 26 having a substantially trapezoidal shape in plan view is arranged between the cutting portion 23 and the second end portion 22. The longer of the parallel sides of the second connecting portion 26 having a substantially trapezoidal shape in plan view is connected to the second end portion 22. The first connecting portion 25 and the second connecting portion 26 are symmetric with respect to the cutting portion 23. As a result, the width in the Y direction of the fuse element 2 gradually widens 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 preferentially heats up and softens, and is easily cut.

[0038] As shown in FIG. 4(a), the width 23D in the Y direction of the cutting portion 23 of the fuse element 2 is narrower than the widths 21D and 22D in the Y direction of the first end portion 21 and the second end portion 22. Therefore, the cross-sectional area in the Y direction of the cutting portion 23 is narrower than the cross-sectional area of the region other than the cutting portion 23 of the fuse element 2. Thereby, the cutting portion 23 is more easily cut than the region between the cutting portion 23 and the first end portion 21 and the region between the cutting portion 23 and the second end portion 22.

[0039] As shown in FIGS. 1 to 4(a), the cut 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 cut portion 23 shown in FIG. 3 is the length in the width direction (Y direction) intersecting the Z direction in the X-direction cross-section shown in FIG. 4(a) (width 23D) or less.

[0040] In the present embodiment, as the fuse element 2, as shown in FIG. 4(a), the width 23D in the Y direction at the cut portion 23 is narrower than the widths 21D and 22D in the Y direction of the first end portion 21 and the second end portion 22. However, the fuse element is not limited to the case where the width in the Y direction of the cut portion is the same as that of the first end portion and the second end portion, and the width in the Y direction of the cut portion may be narrower than that of the first end portion and the second end portion. For example, instead of the fuse element 2 shown in FIG. 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 in the thickness direction (Z direction) in the X-direction (first direction) cross-section of the cut portion of the fuse element is the same as the length in the width direction (Y direction) intersecting the Z direction in the X-direction cross-section.

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

[0042] The fuse element 2 preferably comprises 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 has good soldering properties when the first terminal 61 and the second terminal 62 are soldered to the fuse element 2, which is preferable. 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 more preferable for the current interruption characteristics of the fuse element 2 that the volume of the low melting point metal is larger than the volume of the high melting point metal.

[0043] As the low melting point metal used as the material of the fuse element 2, it is preferable to use Sn or a metal mainly composed of Sn. Since the melting point of Sn is 232°C, the metal mainly composed of Sn has a low melting point and becomes soft at low temperatures. For example, the solidus line of the Sn / Ag 3% / Cu 0.5% alloy is 217°C.

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

[0045] The fuse element 2 in the protection element 100 of the present embodiment preferably has a melting temperature of 600°C or lower, and more preferably 400°C or lower. When the melting temperature is 600°C or lower, the arc discharge generated when the fuse element 2 melts becomes even smaller.

[0046] The fuse element 2 can be manufactured by a known method. For example, 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 can be manufactured by the method shown below. First, a metal foil made of a low melting point metal is prepared. Next, a high melting point metal layer is formed on the entire surface of the metal foil using a plating method to obtain a laminate. Then, the laminate is cut into a predetermined shape. Through the above steps, a fuse element 2 composed of a three-layer laminate is obtained.

[0047] (Case) As shown in FIGS. 1 to 3, the case 6 is substantially a rectangular parallelepiped, and is an integrated body of two members, a first case 6a and a second case 6b arranged opposite to the first case 6a. As shown in FIGS. 1 to 3, the cutting portion 23 of the fuse element 2 is stored in the storage portion 60 provided inside the case 6.

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

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

[0050] As shown in FIGS. 1 and 3, the case 6 in the protection element 100 of the present embodiment is provided with a substantially rectangular parallelepiped housing portion 60 in which the cut portion 23 of the fuse element 2 is housed. The housing portion 60 may be formed by adhering the first case 6a and the second case 6b. Also, the first case 6a and the second case 6b may be fixed by a cover (not shown) disposed outside the case 6.

[0051] As shown in FIG. 3, in the housing portion 60, a first wall surface 60c and a second wall surface 60d, which are planes facing each other in the thickness direction (Z direction) of the cutting portion 23, are provided. Further, as shown in FIGS. 4(b), 5(a), 5(b), 6(a), and 6(b), in the housing portion 60, a third wall surface 60g and a fourth wall surface 60h, which are planes facing each other in the width direction (Y direction) of the cutting portion 23, are provided. Further, as shown in FIGS. 3, 4(b), 5(a), 5(b), 6(a), and 6(b), in the housing portion 60, a fifth wall surface 60e and a sixth wall surface 60f, which are planes facing each other in the (X direction), are provided. The third wall surface 60g and the fourth wall surface 60h, and the fifth wall surface 60e and the sixth wall surface 60f are continuous planes when the first case 6a and the second case 6b are fixed to each other.

[0052] In the present 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 on the second wall surface 60d side of the cutting portion 23 of the fuse element 2 is arranged in contact with the second wall surface 60d.

[0053] In the protection element 100 of the present embodiment, as shown in FIG. 3, 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. For this reason, the number of electric lines of force generated by the arc discharge is sufficiently reduced, and the arc discharge generated when the fuse element 2 melts is small. Further, 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 miniaturized.

[0054] In the protection element 100 of the present embodiment, the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d is preferably not more than 5 times, and more preferably not more than 2 times, the length H23 in the Z direction of the cutting portion 23, because the arc discharge becomes even 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 use of the protection element 100, such as the installation space of the protection element 100, the voltage and current of the current path where the protection element 100 is installed.

[0055] In the protection element 100 of the present embodiment, as shown in FIG. 4(b), the central position of the length between the third wall surface 60g and the fourth wall surface 60h and the central position of the fuse element 2 in the Y direction are arranged to substantially coincide. Regarding the positional relationship in the Y direction between the fuse element 2 and the housing portion 60, as shown in FIG. 4(b), it is preferable that the central position of the length between the third wall surface 60g and the fourth wall surface 60h and the central position of the fuse element 2 in the Y direction substantially coincide. However, the positional relationship in the Y direction between the fuse element 2 and the housing portion 60 is not limited to the example shown in FIG. 4(b) and can be appropriately determined according to the shape of the fuse element 2 and the like.

[0056] In the protection element 100 of the present embodiment, the distance 60D (see FIG. 4(b)) in the width direction (Y direction) of the cutting 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 increase in the housing portion 60 during the fusing of the fuse element 2 is suppressed, and the arc discharge is effectively suppressed. More preferably, the distance 60D in the Y direction between the third wall surface 60g and the fourth wall surface 60h is 2 times or more the widths 21D, 22D of the fuse element 2.

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

[0058] In the protection element 100 of the present embodiment, as shown in FIG. 4(b), the center position of the length 2L in the X direction excluding the region overlapping the first terminal 61 and the second terminal 62 in the fuse element 2 in a plan view, and the center position of the length 6L in the X direction between the fifth wall surface 60e and the sixth wall surface 60f are arranged to substantially coincide. The positional relationship in the X direction between the fuse element 2 and the housing portion 60 is not limited to the example shown in FIG. 4(b), and can be appropriately determined according to the position of the cut portion 23 in the X direction of the fuse element 2 and the like.

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

[0060] Further, the distance 6L in the X direction between the fifth wall surface 60e and the sixth wall surface 60f is preferably 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 housing portion 60, arc discharge may occur between the first terminal 61 and the second terminal 62. For this reason, it is preferable to set the distance 6L to be 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 to reliably shield the arc discharge between the first terminal 61 and the second terminal 62 by the insertion hole forming surfaces 64c and 65c.

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

[0062] As shown in FIGS. 6(a) and 6(b), leak prevention grooves 67c are provided along the fifth wall surface 60e and the sixth wall surface 60f at the joint portion of the second wall surface 60d with the fifth wall surface 60e and at the joint portion of the second wall surface 60d with the sixth wall surface 60f, respectively. The two leak prevention grooves 67c are arranged opposite to each other in the X direction in a plan view. The leak prevention groove 67c is configured to prevent a leakage current by interrupting the current conduction path formed by the deposit when the molten fuse element 2 scatters and adheres to the inside of the housing portion 60 during the fusing of the fuse element 2.

[0063] In the protection element 100 of the present embodiment, it is preferable that the leakage prevention groove 67c is provided, but the leakage prevention groove 67c may not be provided. Further, the position where the leakage 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 at other positions on the second convex portion 68b, or only one of the two leakage prevention grooves 67c may be provided. When the leakage 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 adhering to the inside of the housing portion 60 at the time of fusing of the fuse element 2 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 current conduction path.

[0064] As shown in FIG. 4(b), the length of the leakage prevention groove 67c in the Y direction is preferably longer than the width 21D in the Y direction at the first end portion 21 of the fuse element 2 and the width 22D in the Y direction at the second end portion 22. In this case, it is possible to more effectively prevent the scattered matter adhering to the inside of the housing portion 60 at the time of fusing of the fuse element 2 from being electrically connected to the first terminal 61 or the second terminal 62, and it is possible to more effectively prevent the generation of a leakage current. The leakage prevention groove 67c is formed with a substantially constant width and depth. The width and depth of the leakage prevention groove 67c are not particularly limited as long as the leakage prevention groove 67c can divide the current conduction path formed by the adhering matter scattered at the time of fusing of the fuse element 2 and prevent the leakage current.

[0065] As shown in FIGS. 6(a) and 6(b), on the opposing surface of the second case 6b facing the first case 6a, insertion hole forming surfaces 64c and 65c are provided outside the X direction in a plan view of the leakage prevention groove 67c. The two insertion hole forming surfaces 64c and 65c are arranged to face each other in the X direction in a plan view.

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

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

[0068] As shown in FIGS. 6(a) and 6(b), a terminal mounting surface 64b is provided outside the insertion hole forming surface 64c in the X direction. Also, a terminal mounting surface 65b is provided outside the insertion hole forming surface 65c in the X direction. As shown in FIG. 6(b), the terminal mounting surfaces 64b and 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 and 65c. As a result, steps are formed at the boundary portions between the terminal mounting surfaces 64b and 65b and the insertion hole forming surfaces 64c and 65c, respectively.

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

[0070] The first case 6a is substantially a rectangular parallelepiped. As shown in FIGS. 3, 5(a) and 5(b), when the first joint surface 68a of the first case 6a abuts against the second joint surface 68c of the second case 6b, the accommodating portion 60 is formed. The accommodating portion 60 is composed of a rectangular space in plan view surrounded by the second convex portion 68b of the second case 6b and the first concave portion 68d of the first case 6a.

[0071] As shown in FIG. 5(a), the first concave portion 68d is rectangular in plan view. The planar shape of the first concave portion 68d of the first case 6a is the same as the planar shape of the second convex portion 68b of the second case 6b. As shown in FIGS. 5(a) and 5(b), the first short side of the first concave portion 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 concave portion 68d becomes the first wall surface 60c when the first case 6a and the second case 6b are joined.

[0072] As shown in FIG. 5(a), leak prevention grooves 67d are provided along the fifth wall surface 60e and the sixth wall surface 60f at the joint of the first wall surface 60c with the fifth wall surface 60e and the joint with the sixth wall surface 60f, respectively. The two leak prevention grooves 67d are arranged opposite to each other in the X direction in plan view. Similar to the leak prevention groove 67c provided in the first case 6a, when the fuse element 2 melts during the fusing of the fuse element 2 and the molten fuse element 2 scatters and deposits in the accommodating portion 60, the leak prevention groove 67d cuts off the current conduction path formed by the deposits to prevent leakage current.

[0073] As shown in FIG. 4(b), the length of the leakage 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. Therefore, the leakage prevention groove 67d can be easily formed. The length of the leakage 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 it is preferably longer than the width 21D in the Y direction at the first end portion 21 of the fuse element 2 and the width 22D in the Y direction at the second end portion 22. In this case, it is possible to more effectively prevent the scattered matter adhering to the inside of the housing portion 60 at the time of melting of the fuse element 2 from being electrically connected to the first terminal 61 or the second terminal 62, and it is possible to more effectively prevent the generation of leakage current.

[0074] In the present embodiment, as shown in FIG. 4(b), the central portion in the length direction of the leakage prevention groove 67d provided in the first case 6a is disposed opposite to the central portion in the length direction of the leakage prevention groove 67c of the second case 6b. Further, the end portion in the length direction of the leakage prevention groove 67d is disposed opposite to the first joint surface 68a of the first case 6a.

[0075] In the protection element 100 of the present embodiment, it is preferable that the leakage prevention groove 67d is provided, but the leakage prevention groove 67d may not be provided. Further, the position where the leakage prevention groove 67d is provided is preferably provided along the joint portion between the first wall surface 60c and the fifth wall surface 60e and the joint portion between the first wall surface 60c and the sixth wall surface 60f, but it may be another position on the bottom surface of the first recess 68d, or only one of the two leakage prevention grooves 67d. When the leakage prevention groove 67d is provided along the joint portion between the first wall surface 60c and the fifth wall surface 60e and the joint portion between the first wall surface 60c and the sixth wall surface 60f, it is possible to effectively prevent the scattered matter adhering to the inside of the housing portion 60 at the time of melting of the fuse element 2 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 current conduction 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 only need to be able to divide the current conduction path formed by the deposits scattered during the fusing of the fuse element 2 by the leak prevention groove 67d to prevent leakage, and are not particularly limited.

[0077] As shown in FIGS. 5(a) and 5(b), on the opposing surface of the first case 6a facing the second case 6b, insertion hole forming surfaces 64d and 65d are provided on the outer side in the X direction in plan view of the leak prevention groove 67d. The two insertion hole forming surfaces 64d and 65d are arranged to face each other in the X direction in plan view. As shown in FIG. 5(b), the insertion hole forming surfaces 64d and 65d are provided at positions closer to the first wall surface 60c in the Z direction than the first joint surface 68a. Due to this, steps are formed at the boundary portions between the insertion hole forming surfaces 64d and 65d and the first joint surface 68a, respectively.

[0078] As shown in FIGS. 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. As shown in FIG. 5(b), the terminal mounting surfaces 64a and 65a are at positions closer to the first joint surface 68a in the Z direction than the insertion hole forming surfaces 64d and 65d, and are at positions closer to the first wall surface 60c in the Z direction than the first joint surface 68a. Due to this, steps are formed at the boundary portions between the terminal mounting surfaces 64a and 65a and the insertion hole forming surfaces 64d and 65d and the first joint surface 68a, respectively.

[0079] As shown in FIG. 3, the insertion hole forming surface 64d of the first case 6a and the insertion hole forming surface 64c of the second case 6b are arranged to face each other, thereby forming a first insertion hole 64 that opens to the first wall surface 60c. The insertion hole forming surface 65d of the first case 6a and the insertion hole forming surface 65c of the second case 6b are arranged to face each other, thereby forming a second insertion hole 65 that opens to 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. Also, as shown in FIG. 3, a first terminal 61 is disposed between the terminal mounting surface 64b and the terminal mounting surface 64a. A second terminal 62 is disposed between the terminal mounting surface 65b and the terminal mounting surface 65a.

[0080] On the opposing surface of the first case 6a of the case 6 with the second case 6b, the outer side in the Y direction in the plan view of the third wall surface 60g and the fourth wall surface 60h is a first joint surface 68a 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. As the insulating material, a ceramic material, a resin material, or the like can be used.

[0082] Examples of the ceramic material 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 during the cutting of the fuse element 2 can be efficiently dissipated to the outside, and the continuation of the arc discharge generated during the cutting of the fuse element 2 is more effectively suppressed.

[0083] As the resin material, it is preferable to use any one selected from polyphenylene sulfide (PPS) resin, nylon-based resin, fluorine-based resin such as polytetrafluoroethylene, and polyphthalamide (PPA) resin, and it is particularly preferable to use a nylon-based resin.

[0084] As the nylon-based resin, an aliphatic polyamide or a semi-aromatic polyamide may be used. When an aliphatic polyamide without a benzene ring is used as the nylon-based resin, even if the first case 6a and / or the second case 6b burns due to the arc discharge generated during the fusing of the fuse element 2, graphite is less likely to be generated compared to the case where a semi-aromatic polyamide having 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 formation of a new current conduction path by the graphite generated during the fusing of the fuse element 2.

[0085] As the aliphatic polyamide, for example, nylon 4, nylon 6, nylon 46, nylon 66, etc. can be used. 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 resins without a benzene ring such as nylon 4, nylon 6, nylon 46, nylon 66, etc., which are aliphatic polyamides. Since they have excellent heat resistance, it is more preferable to use nylon 46 or nylon 66.

[0086] As the resin material, it is preferable to use one having 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. The nylon-based resin is particularly preferable among resin materials because of its high tracking resistance (resistance to tracking (carbonized conduction path) breakdown).

[0087] As the resin material, it is preferable to use one with a high glass transition temperature. The glass transition temperature (Tg) of the resin material refers to the temperature at which it changes from a soft rubbery state to a hard glassy state. When the resin is heated above the glass transition temperature, the molecules move more easily and it becomes a soft rubbery state. On the other hand, when the resin cools down, the movement of the molecules is restricted and it becomes a hard glassy state.

[0088] 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 at the time of cutting of the fuse element 2 can be efficiently dissipated to the outside. Therefore, the continuation of the arc discharge generated at the time of cutting of the fuse element 2 is more effectively suppressed. The first case 6a and the second case 6b can be manufactured by known methods.

[0089] (Method for manufacturing a protection element) Next, the manufacturing method of the protection element 100 of the present embodiment will be described with examples. To manufacture the protection element 100 of the present embodiment, a fuse element 2, a first terminal 61, and a second terminal 62 are prepared. Then, as shown in FIG. 4(a), the first terminal 61 is connected by soldering on the first end portion 21 of the fuse element 2. Also, the second terminal 62 is connected by soldering on the second end portion 22.

[0090] As the solder material used for soldering in the present embodiment, known ones can be used, and it is preferable to use one having Sn as the main component from the viewpoints of resistivity, melting point, and environmental compatibility lead-free. The first end portion 21 and the second end portion 22 of the fuse element 2, and the first terminal 61 and the second terminal 62 may be connected by welding, and known joining methods can be used.

[0091] Next, prepare a first case 6a shown in FIGS. 5(a) to 5(c) and a second case 6b shown in FIGS. 6(a) to 6(c). Then, as shown in FIG. 2, install a member in which the fuse element 2, the first terminal 61, and the second terminal 62 are integrated on the second case 6b. As shown in FIG. 2, the member is installed such that the first terminal 61 and the second terminal 62 are arranged on the side of the second wall surface 60d rather than the fuse element 2.

[0092] In the present embodiment, as shown in FIG. 3, by placing the first terminal 61 on the terminal mounting surface 64b and the second terminal 62 on the terminal mounting surface 65b, 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, as shown in FIG. 4(b), the member has a central position in the X direction with a length of 2L excluding the region that overlaps the first terminal 61 and the second terminal 62 in the fuse element 2 in a plan view, and a central position in the X direction with a length of 6L between the fifth wall surface 60e and the sixth wall surface 60f, and is installed such that the central position of the length between the third wall surface 60g and the fourth wall surface 60h coincides with the central position in the Y direction of the fuse element 2.

[0093] Thereafter, join the first case 6a and the second case 6b (see FIG. 3). An adhesive can be used to join the first case 6a and the second case 6b. As the adhesive, for example, an adhesive containing a thermosetting resin can be used. For joining the first case 6a and the second case 6b, a method of winding an adhesive tape made of a resin such as polyimide around the outer surfaces of the first case 6a and the second case 6b may be used. Both an adhesive and an adhesive tape may be used to join the first case 6a and the second case 6b. When joining the first case 6a and the second case 6b, arrange and join them such that the leak prevention groove 67c provided in the second case 6b and the central portion of the leak prevention groove 67d provided in the first case 6a overlap in a plan view (see FIG. 4(b)). The first case 6a and the second case 6b may be fixed by a cover (not shown) arranged outside the case 6.

[0094] By joining the first case 6a and the second case 6b, an accommodation portion 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 within the case 6. At this time, in the protection element 100 of the present 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 formation surfaces 64c and 65c are arranged at positions closer to the first wall surface 60c in the Z direction than the first joint surface 68a of the first case 6a (see FIGS. 3, 5(b), and 6(b)).

[0095] Also, by joining the first case 6a and the second case 6b, as shown in FIG. 3, the first end portion 21 of the fuse element 2 is accommodated in the first insertion hole 64, the second end portion 22 of the fuse element 2 is accommodated in the second insertion hole 65, and a part of the first terminal 61 and the second terminal 62 connected to the fuse element 2 is exposed to the outside of the case 6 (see FIG. 1). Through the above steps, the protection element 100 of the present embodiment is obtained.

[0096] (Operation of the protection element) Next, the operation of the protection element 100 of the present embodiment when a current exceeding the rated current flows through the fuse element 2 will be described. When a current exceeding the rated current flows through the fuse element 2 of the protection element 100 of the present embodiment, the fuse element 2 heats up due to heat generation caused by the overcurrent. Then, when the cutting portion 23 of the fuse element 2 melts due to the temperature rise, it is blown. At this time, a spark is generated between the cut surfaces of the cutting portion 23, and an arc discharge occurs.

[0097] In the protection element 100 of the present embodiment, as shown in FIG. 3, the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d provided in the accommodation 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. For this reason, the amount of moving charges generated by the arc discharge is small, and the arc discharge becomes small-scale.

[0098] As described above, the protection element 100 of the present embodiment has a cutting portion 23 between a first end portion 21 and a second end portion 22, and includes a fuse element 2 that is energized in a first direction (X direction) from the first end portion 21 toward the second end portion 22, and a case 6 made of an insulating material and provided therein with a housing portion 60 that houses the cutting portion 23. In the protection element 100 of the present embodiment, the length H23 in the thickness direction (Z direction) of the cross section of the cutting portion 23 in the first direction (X direction) is equal to or less than the length in the width direction (Y direction) that intersects the thickness direction (Z direction) of the cross section in the first direction (X direction). In the housing portion 60, a first wall surface 60c and a second wall surface 60d each formed of a plane facing in the Z direction are provided, 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 in the Z direction of the cutting portion 23. As a result, the following effects can be obtained.

[0099] That is, in the protection element 100 of the present embodiment, the arc discharge generated when the fuse element 2 melts is small. Therefore, in the protection element 100 of the present embodiment, it is possible to prevent the housing portion 60 from being destroyed due to a pressure increase in the housing portion 60, and the safety is excellent. Further, the protection element 100 of the present embodiment can be preferably installed in a current path having a high voltage of 100 V or more and a large current of 100 A or more, for example.

[0100] Further, in the protection element 100 of the present embodiment, since the distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d is short, the size can be reduced. Furthermore, in the protection element 100 of the present embodiment, since the arc discharge is small, the thickness between the housing portion 60 of the case 6 and the outer surface can be reduced to reduce the size. Therefore, according to the protection element 100 of the present embodiment, the amount of material used for the case 6 can be reduced.

[0101] Moreover, in the protection element 100 of the present embodiment, the entire surface 23b of the cutting portion 23 of the fuse element 2 on the second wall surface 60d side is disposed in contact with the second wall surface 60d. For this reason, in the protection element 100 of the present embodiment, the number of electric lines of force on the surface 23b of the cutting portion 23 on the second wall surface 60d side generated by arc discharge is reduced, and the heat generated when the fuse element 2 is cut can be efficiently dissipated to the outside through the second wall surface 60d. For this reason, the arc discharge generated when the fuse element 2 is blown is reduced to a smaller scale. Moreover, when the entire surface 23b of the cutting portion 23 on the second wall surface 60d side is disposed in contact with the second wall surface 60d, the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d can be made even shorter, and further miniaturization is possible.

[0102] In the protection element 100 of the present embodiment, it is more preferable that the fuse element 2 is composed 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 formed of a resin material. In such a protection element, for the reasons shown below, the arc discharge generated when the fuse element 2 is blown is further reduced to a smaller scale, and further miniaturization is possible.

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

[0104] Moreover, in such a protection element, due to the heat generated when the fuse element 2 melts, the resin material forming the case 6 decomposes to generate pyrolysis gas, and the heat of vaporization cools the inside of the accommodation portion 60 (ablation effect by the resin). As a result, the arc discharge becomes even smaller. From these facts, in a protection element in which the fuse element 2 is made of the above laminate and the case 6 is formed of a resin material, the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d in the accommodation portion 60 can be shortened, making the arc discharge even smaller and enabling further miniaturization.

[0105] Examples of resin materials that are likely to obtain the ablation effect due to the heat generated when the fuse element 2 melts include nylon 46, nylon 66, polyacetal (POM), polyethylene terephthalate (PET), and the like. Note that, 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 by the resin is more effectively obtained when the Y-direction distance 60D (see FIG. 4(b)) between the third wall surface 60g and the fourth wall surface 60h in the accommodation portion 60 is 1.5 times or more the Y-direction length (widths 21D, 22D) of the fuse element 2. This is presumably because even if the Y-direction distance 60D in the accommodation portion 60 is increased, the number of electric force lines generated by the arc discharge is little affected, while the surface area inside the accommodation portion 60 significantly increases, promoting the decomposition of the resin material due to the heat generated when the fuse element 2 melts.

[0107] On the other hand, for example, in a protection element in which the fuse element is made of Cu and the case is made of a ceramic material, it may be difficult to miniaturize for the following reasons. That is, when the fuse element is made of Cu, the fusing temperature of the fuse element becomes a high temperature of 1000°C or more. Therefore, if a resin material is used as the material of the case, the heat resistance of the case may be insufficient. Therefore, as the material of the case, a ceramic material, which is a material excellent in heat resistance, is used.

[0108] In this protection element, since the fusing temperature of the fuse element is high and a ceramic material is used as the material of the case, if the distance between the cut portion of the fuse element and the inner surface of the case is made close, the heat generated at the cut portion is dissipated through the case, and it becomes difficult for the fuse element to reach the fusing temperature. For this reason, it is necessary to secure a sufficient distance between the cut portion and the inner surface of the case. Therefore, in a protection element in which the fuse element is made of Cu and the case is made of a ceramic material, a wide accommodating portion must be provided in the case.

[0109] Moreover, when a sufficient distance is secured between the cut portion and the inner surface of the case, the number of electric lines of force generated by arc discharge increases, so that the arc discharge generated at the time of fusing of the fuse element becomes large-scale. For this reason, in order to quickly extinguish (arc extinction) the arc discharge, it may be necessary to put an arc extinguishing agent in the accommodating portion in the case. When putting an arc extinguishing agent in the case, it is necessary to secure a space for accommodating the arc extinguishing agent in the case. For this reason, it becomes necessary to provide an even wider accommodating portion in the case, and it may become even more difficult to miniaturize.

[0110] [Second Embodiment] FIG. 7 is a cross-sectional view for explaining the protection element 200 of the second embodiment, and is a cross-sectional view corresponding to the position where the protection element 100 according to the first embodiment is cut along the line A-A' shown in FIG. 1. In the protection element 200 according to the second embodiment, the same members as those of the protection element 100 according to the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

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

[0112] As shown in FIG. 7, within the housing portion 60 of the protection element 200 of the present embodiment, a first wall surface 60c and a second wall surface 60d, which are planes facing each other in the thickness direction (Z direction) of the cutting portion 23, are provided. In the protection element 200 of the present embodiment, similar 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 is set to be 10 times or less the length H23 in the Z direction of the cutting portion 23. Also in the protection element 200 of the present 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 the length H23 in the Z direction of the cutting portion 23, and more preferably 2 times or less.

[0113] In the protection element 200 of the present embodiment, as shown in FIG. 7, 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 one may be longer between the distance H6a and the distance H6b.

[0114] In the protection element 200 of the present embodiment, as shown in FIG. 7, a space 60b is provided between the fuse element 2 and the second wall surface 60d. For this reason, instead of the second convex portion 68b provided on the second case 6b in the protection element 100 according to the first embodiment, a second concave portion 68e shown in FIG. 7 is provided in the protection element 200 of the present embodiment. The planar shape of the second concave portion 68e is rectangular in plan view and is the same shape as the planar shape of the first concave portion 68d of the first case 6a and the second convex portion 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, 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. 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. 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 the present embodiment can be manufactured in the same manner as the protection element 100 of the first embodiment, using, as the second case 6b, one provided with the second recess 68e shown in FIG. 7 instead of the second convex portion 68b shown in FIGS. 6(a) and 6(b).

[0117] Similar to the protection element 100 of the first embodiment, in the protection element 200 of the present 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 10 times or less the length H23 in the Z direction of the cut portion 23 of the fuse element 2. Therefore, also in the protection element 200 of the present embodiment, similar to the protection element 100 of the first embodiment, the arc discharge generated when the fuse element 2 melts is reduced in scale and miniaturization is possible.

[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 FIG. 3, a space 60a is provided between the fuse element 2 and the first wall surface 60c, and the entire surface 23b on the second wall surface 60d side of the cut portion 23 of the fuse element 2 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 FIG. 3, and the surface on the first wall surface 60c side of the cut portion 23 is arranged in contact with the first wall surface 60c.

[0119] Further, in the protection element of the present invention, the surface 23b on the second wall surface 60d side of the cut portion 23 shown in FIG. 3 may be arranged in contact with the second wall surface 60d, and the surface on the first wall surface 60c side of the cut portion 23 may be arranged in contact with the first wall surface 60c. In this case, the number of electric lines of force on the surface 23b on the second wall surface 60d side of the cut portion 23 generated by arc discharge decreases, and the number of electric lines of force on the surface 23b on the first wall surface 60c side of the cut portion 23 generated by arc discharge also decreases. Moreover, the heat generated when the fuse element 2 is cut is efficiently radiated to the outside through the second wall surface 60d and the first wall surface 60c. As a result, the arc discharge generated when the fuse element 2 melts becomes smaller. Moreover, since the surface 23b on the second wall surface 60d side and the surface on the first wall surface 60c side in the cut portion 23 are arranged in contact with the inner surface of the accommodating 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 size can be further reduced.

[0120] Further, the protection element of the present invention may be provided with a shielding mechanism as needed. Examples of the shielding mechanism include a slider component having an opening through which the fuse element is disposed. The slider component moves in the Z direction orthogonal to the energization direction of the fuse element during melting, and physically closes the first insertion hole. As a result, the cut surfaces of the cut fuse elements are insulated from each other, and the arc discharge generated when the fuse element melts is quickly extinguished (arrested).

Example

[0121] Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. Note that the present invention is not limited to only the following examples.

[0122] (Example 1) The protection element 100 of Example 1 shown in FIG. 1 was manufactured by the method shown below. As the fuse element 2, one with a resistance value of 0.5 mΩ and the following dimensions and materials was prepared. Width of the fuse element 2 (distance 21D, 22D in the Y direction): 6.5 mm Width of the cut portion 23 (distance 23D in the Y direction): approximately 5.4 mm Thickness of the cut portion 23 (distance H23 in the Z direction): 0.2 mm Material: The entire surface of the inner layer made of an alloy mainly composed of Sn is coated with an outer layer made of an Ag plating layer with a minimum thickness of 10 μm, so that the outer layer, the inner layer, and the outer layer are laminated in this order in the thickness direction.

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

[0124] As the case 6, one with an outer shape in a rectangular parallelepiped shape with a length (length in the X direction) of 16.8 mm, a width (length in the Y direction) of 18.0 mm, and a height (length in the Z direction) of 10 mm in a state where the first case 6a and the second case 6b are joined was prepared. As the material of the case 6, nylon 66 (product name; N66(NC), manufactured by Toray Industries, Inc.) was used.

[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 distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d in the accommodation portion 60 was set to 0.75 mm. Also, 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 in the accommodation portion 60 was set to 14 mm, and the length 6L in the X direction between the fifth wall surface 60e and the sixth wall surface 60f in the accommodation portion 60 was set to 8.0 mm.

[0126] Next, a member in which the fuse element 2, the first terminal 61, and the second terminal 62 are integrated was placed on the second case 6b. At this time, the center position of the length 2L in the X direction excluding the region overlapping with the first terminal 61 and the second terminal 62 in the fuse element 2 in 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 in the Y direction of the fuse element 2, and it was installed in this way.

[0127] After that, the first case 6a was placed on the member in which the fuse element 2, the first terminal 61, and the second terminal 62 are integrated, and the first case 6a and the second case 6b were joined by winding 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 protection element of Example 1 was obtained.

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

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

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

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

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

[0133] The protective elements of Example 1 to Example 5 and Comparative Example 1 obtained in this way were installed in a current path with a voltage of 150 V and a current of 2000 A, and the current was interrupted. Then, for the protective elements of Example 1 to Example 5 and Comparative Example 1, the following items were measured and evaluated. FIG. 13 is a drawing showing the measurement results of the protective elements of Example 1 to Example 3 and the evaluation results when interrupted at a voltage of 150 V and a current of 2000 A. FIG. 14 is a drawing showing the measurement results of the protective elements of Example 4, Example 5, and Comparative Example 1 and the evaluation results when interrupted at a voltage of 150 V and a current of 2000 A.

[0134] (Space height) The Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d in the accommodation portion 60 was calculated from the depth dimension of the first concave portion 68d of the first case 6a and the height dimension of the second convex portion 68b or the depth dimension of the second concave portion 68e in the second case 6b, and was used as the space height.

[0135] (Cut-off time) Using a current probe capable of measuring a current of 2000 A or more, the time from the start of energization until the current was cut off was measured. (Fusing length) The X-direction length of the member in which the fuse element 2, the first terminal 61, and the second terminal 62 were integrated and which melted at the time of current interruption was measured and used as the fusing length. The arrow described in the X-ray top view after the test indicates the fusing 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 at the time of current interruption.

[0136] (X-ray top view before the test) An X-ray photograph obtained by photographing the protection elements of Example 1 to Example 5 and Comparative Example 1 before current supply from the first case 6a side using an X-ray imaging device. (X-ray side view before the test) An X-ray photograph obtained by photographing the protection elements of Example 1 to Example 5 and Comparative Example 1 before current supply as viewed from the Y direction using the above X-ray imaging device. The light gray portion in the photograph is a space. The dark gray portion is the case. The black portion crossing the center of the photograph is the member in which the fuse element 2, the first terminal 61, and the second terminal 62 are integrated. (X-ray top view after the test) An X-ray photograph obtained by photographing the protection elements of Example 1 to Example 5 and Comparative Example 1 after current interruption from the first case 6a side using the above X-ray imaging device.

[0137] (At the time of interruption) A photograph of the arc discharge state of the protection elements of Example 1 to Example 4. For the protection elements of Example 5 and Comparative Example 1, the photographed photographs were white due to the light caused by the arc discharge. (Judgment) Evaluation was performed according to the following criteria. ◎: Only the fuse element was melted. 〇: In addition to the fuse element, melting of the first terminal and the second terminal was observed, but a part of the collar portions of the first terminal and the second terminal remained without melting. △: In addition to the fuse element, melting of the collar portions of the first terminal and the second terminal was observed, but a part of the first terminal and the second terminal remained inside the case. ×: In addition to the fuse element, the first terminal and the second terminal were melted to the outside of the case.

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

[0139] As shown in FIG. 13, in the protection element of Example 2, as shown in the post-test X-ray top photograph, only the fuse element 2 was melted, and the first terminal 61 and the second terminal 62 were cut off without melting. Further, in the protection elements of Examples 1 to 3, as shown in the photograph at the time of interruption, the arc discharge generated at the time of fusing of the fuse element 2 was small. Further, from the results of the protection elements of Examples 1 to 3, it was confirmed that the lower the space height, the shorter the interruption time and the interruption length, and the smaller the arc discharge.

[0140] Also, as shown in the pre-test X-ray side photograph in Fig. 14, in the protective elements of Example 4, Example 5, and Comparative Example 1, spaces are 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 Fig. 14, in the protective elements of Example 4 and Example 5, as shown in the post-test X-ray top photograph, although the collar portions of the first terminal 61 and the second terminal 62 melted, a part of the first terminal 61 and the second terminal 62 remained inside the case without melting. In contrast, 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 with Examples 1 to 5. Also, as shown in Fig. 14, in the protective elements of Example 4, Example 5, and Comparative Example 1, similar to the protective elements of Examples 1 to 3, it was confirmed that the shorter the space height, the shorter the cut-off time and the smaller the arc discharge.

[0142] For the protective elements of Examples 1, 3, and 4, the length 2L in the X direction excluding the region overlapping with the first terminal 61 and the second terminal 62 in the fuse element 2 in plan view is 9.5 mm. In the protective elements of Examples 1, 3, and 4, since the arc discharge was relatively small-scale, it is presumed that by making the length 2L longer than 9.5 mm, the melting of the first terminal 61 and the second terminal 62 can be suppressed.

[0143] Also, the protective element of Example 3 (space height: 1.75 mm) has a higher space height than the protective element of Example 4 (space height: 1.5 mm), but the cut-off time and the cut-off length are shorter than those of the protective element of Example 4. This is presumably because in the protective element of Example 3, the entire surface on the second wall surface 60d side at the cut portion 23 of the fuse element 2 is arranged in contact with the second wall surface 60d, so that the arc discharge is further suppressed.

[0144] Therefore, in the protection element of Example 5, similar to Example 3, by arranging the entire surface on the second wall surface 60d side at the cut portion 23 of the fuse element 2 in contact with the second wall surface 60d, it is estimated that even when the space height is 2.0 mm (10 times the length in the thickness direction of the fuse element 2), arc discharge can be suppressed on a small scale.

[0145] (Protection element A) As the protection element A which is an embodiment of the present invention, the same protection element as that of Example 1 was created except that a shielding mechanism was added to the cut portion 23. The protection element A includes, as a shielding mechanism, a slider component having an opening through which a fuse element is disposed. The slider component moves in the Z direction orthogonal to the energization direction of the fuse element during fusing to physically block the first insertion hole. FIG. 8 is a photograph of a state in which a member in which a fuse element, a first terminal, and a second terminal used in the protection element A are integrated is installed on a second case together with a slider component. The fuse element is integrated with the first terminal and the second terminal in a state of 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 distance H6 in the Z direction between the first wall surface 60c and the second wall surface 60d in the housing portion 60 was set to 14 mm, 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 was set to 24.6 mm, and the length 6L in the X direction between the fifth wall surface 60e and the sixth wall surface 60f in the housing portion 60 was set to 13.6 mm.

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

[0148] As shown in FIG. 9, in the protection element B in which the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d is 14 mm (70 times the thickness (0.2 mm) of the cutting portion 23), large-scale arc discharge occurred, and sparks were emitted from the protection element together with an explosion sound. Further, 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 were melted.

[0149] On the other hand, as shown in FIG. 11, in the protection element A in which the Z-direction distance H6 between the first wall surface 60c and the second wall surface 60d is 0.75 mm (3.75 times the thickness (0.2 mm) of the cutting portion), the arc discharge was smaller than that of the protection element B. Further, as shown in FIG. 12, in the protection element A, the current was interrupted by melting only a part of the fuse element 2. Further, in the protection element A, the insulation resistance was 1.36×10 12 Ω, which was good.

Explanation of reference numerals

[0150] 2 Fuse element 4 Electric lines of force 6 Case 6a First case 6b Second case 21 First end 22 Second end 23 Cutting portion 25 First connecting portion 26 Second connecting portion 60 Housing portion 60a, 60b Spaces 60c First wall surface 60d Second wall surface 60e Fifth wall surface 60f Sixth wall surface 60g Third wall surface 60h Fourth wall surface 61 First terminal 61a, 62a External terminal holes 61c, 62c Flange portions 62 Second terminal 64 First insertion hole 64a, 64b, 65a, 65b Terminal mounting surfaces 64c, 64d, 65c, 65d Insertion hole forming surfaces 65 Second insertion hole 67c, 67d Leakage prevention grooves 68a First joint surface 68b Second convex portion 68c Second joint surface 68d First concave portion 68e Second concave portion 100, 200 Protective elements

Claims

1. A fuse element having a cut portion between a first end portion and a second end portion, and being energized in a first direction from the first end portion toward the second end portion; A case made of an insulating material and having an accommodation portion provided therein for accommodating the cut portion; The length in the thickness direction of the cut portion in the cross-section in the first direction is equal to or less than the length in the width direction intersecting the thickness direction in the cross-section in the first direction; In the accommodation portion, a first wall surface and a second wall surface facing each other in the thickness direction are provided; The distance in the thickness direction between the first wall surface and the second wall surface is equal to or less than 10 times the length in the thickness direction of the cut portion; The cut portion is disposed in contact with one or both of the first wall surface and the second wall surface; In the accommodation portion, a third wall surface and a fourth wall surface facing each other in the width direction are provided; The distance in the width direction between the third wall surface and the fourth wall surface is equal to or more than 1.5 times the length in the width direction of the fuse element; The case is a protective element formed of a resin material having a tracking resistance index CTI of 400 V or more.

2. The protective element according to claim 1, wherein the distance in the thickness direction between the first wall surface and the second wall surface is equal to or less than 5 times the length in the thickness direction of the cut portion.

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

4. The protective element according to claim 1, wherein the distance in the width direction between the third wall surface and the fourth wall surface is from 2 times to 5 times the length in the width direction of the fuse element.

5. The protective element according to any one of claims 1 to 4, wherein the fuse element is flat or linear.

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

7. The protective element according to any one of claims 1 to 6, wherein the melting temperature of the fuse element is 600°C or less.

8. The protective element according to any one of claims 1 to 6, wherein the melting temperature of the fuse element is 400°C or less.

9. The protective element according to any one of claims 1 to 8, 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.

10. The low melting point metal is made of Sn or a metal containing Sn as a main component, 10. The protective element according to claim 9, wherein the high melting point metal is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

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

12. 12. 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.

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

Images