Protective element

Abstract

This protective element comprises a fuse element (50), a first terminal (91) and a second terminal (92) that are connected to both electric-conduction-direction ends of the first fuse element (50), and an insulation case (10) that accommodates the fuse element (50) and portions of the first terminal (91) and the second terminal (92). An element accommodation space (53) is formed in the insulation case (10) such that a portion of the insulation case (10) is in proximity to or in contact with at least a portion of the fuse element (50). The rated voltage of the protective element is equal to or less than a value obtained by multiplying an inter-terminal distance (D) [mm] between the first terminal (91) and the second terminal (92) by an electric field intensity of 30 [V / mm].

Description

Protection Elements

[0001] The present invention relates to a protection element. The present invention claims priority based on Japanese Patent Application No. 2024-088970, filed on May 31, 2024, the contents of which are incorporated herein by reference.

[0002] Conventionally, fuse elements are known that generate heat and melt to interrupt a current path when a current exceeding the rated current flows through the current path (see, for example, Patent Document 1). Protective devices (fuse elements) equipped with fuse elements are used in a wide range of fields, from home appliances to electric vehicles.

[0003] For example, lithium-ion batteries are used in a wide range of applications, from mobile devices to electric vehicles (EVs) and storage batteries, and their capacity is increasing. As the capacity of lithium-ion batteries increases, they are required to have high voltage specifications of several hundred volts and high current specifications of several hundred to several thousand amperes.

[0004] Japanese Patent Application Publication No. 2024-35821

[0005] Arc discharge during interruption is an issue for protective elements capable of interrupting high voltages and large currents. To suppress arc discharge, a substance called silica sand, known as an arc-extinguishing agent, is typically packed around the fuse element. Furthermore, as protective elements become smaller and less resistant (shorter), the fuse element's fusing section becomes wider and thicker. In this case, there is a concern that molten debris may continuously adhere to the surface of the arc-extinguishing agent, reducing interruption characteristics and increasing the risk of reduced insulation resistance after interruption. Furthermore, even if the appropriate fuse element and arc-extinguishing agent are used, arc discharge becomes an issue as voltages continue to increase.

[0006] An object of the present invention is to provide a protection element that can suppress arc discharge during interruption, can handle high voltage and large current interruption, and can suppress a decrease in insulation resistance after interruption.

[0007] In order to solve the above problems, the present invention provides the following means.

[0008] [Aspect 1 of the Present Invention] A protective element comprising: a fuse element; first and second terminals connected to both ends of the fuse element in a current-carrying direction; and an insulating case that accommodates portions of the first and second terminals and the fuse element, wherein an element accommodating space is formed in the insulating case such that a portion of the insulating case is in close proximity to or in contact with at least a portion of the fuse element, and the rated voltage of the protective element is equal to or less than a value obtained by multiplying the inter-terminal distance D [mm] between the first and second terminals by an electric field strength of 30 [V / mm].

[0009] [Aspect 2 of the present invention] The protection element according to aspect 1, wherein the fuse element has a first conductor and a fusible conductor, and the first conductor and the fusible conductor are connected in series in the current-carrying direction.

[0010] [Aspect 3 of the Present Invention] The protection element according to Aspect 2, wherein the first conductor includes a first buffer portion that relieves physical stress, and the insulating case has a first buffer space formed around the first buffer portion.

[0011] Aspect 4 of the Present Invention The protection element according to aspect 3, wherein the first buffer space is filled with a first filling material.

[0012] [Aspect 5 of the present invention] The fuse element further has a second conductor, the first conductor is connected to one end of the fusible conductor, the second conductor is connected to the other end of the fusible conductor, the second conductor has a second buffer part that relieves physical stress, a second buffer space is formed in the insulating case around the second buffer part, and the second buffer space is filled with a second filler, The protective element according to aspect 4.

[0013] [Aspect 6 of the Present Invention] The protection element according to aspect 5, wherein the insulating case has an internal pressure buffer space that communicates with the element accommodating space and that allows gas generated when the fuse element interrupts an overcurrent to escape.

[0014] [Aspect 7 of the present invention] The protective element according to Aspect 6, wherein the internal pressure buffering space is filled with a third filler, and a leak hole and / or a gap communicating between the element accommodating space and the internal pressure buffering space is not filled with anything.

[0015] [Aspect 8 of the Present Invention] The protection element according to any one of Aspects 5 to 7, wherein each of the first conductor and the second conductor is a plate-shaped member made of metal.

[0016] Aspect 9 of the Present Invention The protection element according to any one of Aspects 5 to 8, wherein each of the first conductor and the second conductor is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

[0017] [Aspect 10 of the present invention] The protective element according to any one of aspects 2 to 9, wherein the fusible conductor is made of Sn or a metal mainly composed of Sn.

[0018] [Aspect 11 of the present invention] The protection element according to any one of aspects 2 to 10, wherein the soluble conductor is a laminate including a high melting point metal layer and a low melting point metal layer.

[0019] [Aspect 12 of the Present Invention] The protection element according to aspect 11, wherein the high-melting-point metal layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component, and the low-melting-point metal layer is made of Sn or a metal containing Sn as a main component.

[0020] [Aspect 13 of the Present Invention] The protective element according to aspect 6 or 7, wherein the insulating case includes at least a first holding member in which the first buffer space is formed, a second holding member in which the internal pressure buffer space is formed, and a cover inserted from a direction perpendicular to a direction in which the first holding member and the second holding member are stacked.

[0021] [Aspect 14 of the Present Invention] The protection element according to aspect 13, further comprising a third holding member disposed inside the cover and shielding an open surface of the internal pressure buffering space of the second holding member.

[0022] [Aspect 15 of the Present Invention] The protection element according to any one of aspects 5 to 9, wherein each of the first filling material and the second filling material is made of an elastic resin.

[0023] Aspect 16 of the Present Invention The protection element according to aspect 15, wherein the elastic resin is a silicone resin.

[0024] Aspect 17 of the Present Invention The protective element according to aspect 7, wherein the third filler includes at least insulating fiber or silica sand.

[0025] [Aspect 18 of the Present Invention] The protection element according to aspect 17, wherein the insulating fiber is ceramic fiber paper.

[0026] [Aspect 19 of the present invention] The protection element according to any one of aspects 2 to 18, wherein flux is applied to at least one surface of the fusible conductor.

[0027] [Aspect 20 of the Present Invention] The protective element according to any one of aspects 1 to 19, wherein the insulating case is made of a polyamide resin or a fluorine-based resin.

[0028] [Aspect 21 of the Present Invention] The protection element according to any one of aspects 1 to 20, wherein a plurality of the fuse elements are provided in parallel.

[0029] [Aspect 22 of the Present Invention] The protection element according to any one of Aspects 1 to 21, wherein a heating element that melts the fuse element by generating heat is connected to a part of the fuse element.

[0030] Aspect 23 of the present invention is the protection element according to any one of aspects 1 to 22, wherein the rated voltage is equal to or greater than a value obtained by multiplying the inter-terminal distance D [mm] by an electric field strength of 15 [V / mm].

[0031] Aspect 24 of the Present Invention The protection element according to any one of Aspects 1 to 23, wherein the rated voltage is equal to or greater than a value obtained by multiplying the inter-terminal distance D [mm] by an electric field strength of 20 [V / mm].

[0032] According to the above aspects of the present invention, it is possible to provide a protective element that can suppress arc discharge during interruption, can handle high voltage and large current interruption, and can suppress a decrease in insulation resistance after interruption.

[0033] FIG. 1 is a perspective view (cross-sectional perspective view) showing the appearance and cross section of a protection element of this embodiment. FIG. 2 is an exploded perspective view showing the protection element of this embodiment. FIG. 3 is an exploded perspective view showing a portion of the protection element of FIG. 2. FIG. 4 is an enlarged cross-sectional view showing the vicinity of section IV in FIG. 1. FIG. 5 is an enlarged cross-sectional view showing section V in FIG. 4. FIG. 6A is a perspective view showing a heating element. FIG. 6B is a top view showing an example of a heating element. FIG. 6C is a top view showing another example of a heating element. FIG. 7 is a cross-sectional view corresponding to FIG. 5, showing a state in which a portion of the fuse element has melted due to heat generated by the heating element in response to a shut-off signal. FIG. 8 is a cross-sectional view corresponding to FIG. 5, showing a state in which a portion of the fuse element has melted (disappeared) due to an overcurrent. FIG. 9 is a perspective view (cross-sectional perspective view) showing the appearance and cross section of a protection element of a first modified example of this embodiment. FIG. 10 is a perspective view (cross-sectional perspective view) showing the appearance and cross section of a protection element of a second modified example of this embodiment. FIG. 11 is a cross-sectional view showing a portion of a protection element of a third modified example of this embodiment. FIG. 12 is a cross-sectional view showing a portion of a protection element according to a fourth modified example of this embodiment. FIG. 13 is a cross-sectional view showing a portion of a protection element according to a fourth modified example of this embodiment, illustrating a state in which a portion of the fuse element has been melted. FIG. 14 is a cross-sectional view showing a portion of a protection element according to a fifth modified example of this embodiment. FIG. 15 is a top view showing a portion (fuse element) of a protection element according to a sixth modified example of this embodiment. FIG. 16 is a top view showing a portion (fuse element) of a protection element according to a seventh modified example of this embodiment. FIG. 17 is a cross-sectional view showing a portion of a protection element according to an eighth modified example of this embodiment. FIG. 18 is a top view showing a portion (heating element) of a protection element according to a ninth modified example of this embodiment. FIG. 19 is a top view showing a portion (heating element) of a protection element according to a tenth modified example of this embodiment. FIG. 20 is a perspective view showing a portion (heating element) of a protection element according to an eleventh modified example of this embodiment. FIG. 21 is a perspective view showing a portion (heating element) of a protection element according to a twelfth modified example of this embodiment. FIG. 22 is a perspective view showing a portion (heating element) of a protection element according to a thirteenth modified example of this embodiment. FIG. 23 is a cross-sectional view showing a portion of a protection element according to a fourteenth modified example of this embodiment. Fig. 24 is a top view showing an example of the heat generating element of the second embodiment. Fig. 25 is a top view showing another example of the heat generating element of the second embodiment.FIG. 26 is a side view of an insulating substrate of the second embodiment, showing the state before the current-carrying member is connected. FIG. 27 is a side view of an insulating substrate of the second embodiment, showing the state after the current-carrying member is connected and before current is applied. FIG. 28 is a side view of an insulating substrate of the second embodiment, showing the state after current is applied and a part of the fuse element is melted. FIG. 29 is a side view of an insulating substrate of the second embodiment, showing the state after current is applied and a part of the electrode of the heating element is melted. FIG. 30 is a perspective view of an insulating substrate of the second embodiment, showing the state before the current-carrying member is connected (the insulating layer is shown by a two-dot chain line). FIG. 31 is a perspective view of an insulating substrate of the second embodiment, showing the state before the current-carrying member is connected (the insulating layer is shown by a solid line). FIG. 32 is a perspective view of an insulating substrate of the second embodiment, showing the state after the current-carrying member is connected. FIG. 33 is a perspective view of an insulating substrate of the second embodiment, showing the state after the current-carrying member is connected. FIG. 34 is a perspective view of an insulating substrate according to a modified example of the second embodiment, showing the state before the current-carrying member is connected (the insulating layer is shown by a two-dot chain line). FIG. 35 is a perspective view of an insulating substrate according to a modified example of the second embodiment, showing the state before the current-carrying member is connected (the insulating layer is shown by a solid line). FIG. 36 is a cross-sectional view showing an example of a filler according to the third embodiment. FIG. 37 is a cross-sectional view showing an example of the arrangement of the filler according to the third embodiment. FIG. 38 is a cross-sectional view showing another example of the filler according to the third embodiment. FIG. 39 is a cross-sectional view showing another example of the filler according to the third embodiment. FIG. 40 is a cross-sectional view showing another example of the filler according to the third embodiment. FIG. 41 is a cross-sectional view showing an example of a filter according to the fourth embodiment. FIG. 42 is a cross-sectional view showing an example of the arrangement of the filter according to the fourth embodiment. FIG. 43 is a perspective view (cross-sectional perspective view) showing the appearance and cross section of a protection element according to the fifth embodiment. FIG. 44 is a side view of the insulating member according to the fifth embodiment, showing the state before the circuit is interrupted due to an overcurrent. Fig. 45 is a side view of the insulating member of the fifth embodiment, showing a state in which a part of the insulating member has melted after interruption due to an overcurrent. Fig. 46 is a top view showing a part (fuse element) of a protection element of a sixth embodiment. Fig. 47 is a side view showing a part (fuse element) of a protection element of the sixth embodiment. Fig. 48 is a top view showing an example of a part (fuse element) of a protection element of the sixth embodiment. Fig. 49 is a top view showing another example of a part (fuse element) of a protection element of the sixth embodiment.FIG. 50 is a top view showing another example of a portion (fuse element) of the protection element of the sixth embodiment. FIG. 51 is a top view showing another example of a portion (fuse element) of the protection element of the sixth embodiment. FIG. 52 is a top view showing another example of a portion (fuse element) of the protection element of the sixth embodiment. FIG. 53 is a top view showing another example of a portion (fuse element) of the protection element of the sixth embodiment. FIG. 54 is a top view showing a portion (fuse element) of a protection element of a comparative example. FIG. 55 is a diagram showing the results of a high-voltage, large-current interruption test of the protection element of the comparative example. FIG. 56 is a diagram showing the results of a high-voltage, large-current interruption test of the protection element of Example 1. FIG. 57 is a diagram showing the results of a high-voltage, large-current interruption test of the protection element of Example 2. This is a cross-sectional view of the protection element of the seventh embodiment taken along line LVIII-LVIII of FIG. 59. This is a cross-sectional view of the protection element of the seventh embodiment taken along line LIX-LIX of FIG. 58. This is a side view of the protection element of the seventh embodiment taken along arrow LX of FIG. 59. 64. A cross-sectional view taken along LXI-LXI of FIG. 58. A cross-sectional view taken along LXII-LXII of FIG. 58. A cross-sectional view taken along LXIII-LXIII of FIG. 64, showing a protection element of the eighth embodiment. A cross-sectional view taken along LXIV-LXIV of FIG. 63, showing a protection element of the eighth embodiment. A side view of the protection element of the eighth embodiment, viewed from the arrow LXV of FIG. 64. A cross-sectional view taken along LXVI-LXVI of FIG. 63. A cross-sectional view shown in FIG. 64, showing a protection element of the ninth embodiment, corresponding to FIG. 59. A cross-sectional view shown in FIG. 67, showing a protection element of the tenth embodiment, corresponding to FIG. 59. A diagram showing an example of a protection element with a rated voltage of 420 V. A diagram showing a first example of a protection element having a crank structure. A diagram showing a second example of a protection element having a crank structure. A diagram showing a third example of a protection element having a crank structure.

[0034] (Protection Element (Present Embodiment)) A protection element 100 according to one embodiment of the present invention will be described with reference to FIGS. 1 to 8. The protection element 100 according to this embodiment is an electrical component that constitutes part of a high-voltage, high-current (100 V / 100 A or more) electrical circuit that uses, for example, a lithium-ion battery. The protection element 100 is mounted on, for example, an electric vehicle (EV).

[0035] 1 to 3 , the protective element 100 includes a first terminal 91 and a second terminal 92 spaced apart from each other in a predetermined direction, a fusible fuse element 50 disposed between the first terminal 91 and the second terminal 92 to electrically connect them, an insulating member 60 disposed opposite the fuse element 50, a heating element 80 disposed overlapping the fuse element 50, a power supply member 90 that supplies current to the heating element 80, and an insulating case 10 that accommodates a portion of the first terminal 91, a portion of the second terminal 92, the fuse element 50, the insulating member 60, the heating element 80, and a portion of the power supply member 90. The first terminal 91 and the second terminal 92 are each plate-shaped.

[0036] The protective element 100 of this embodiment has a mechanism for interrupting the current path, which includes an overcurrent interruption mechanism in which the fuse element 50 melts and interrupts the current path when an overcurrent (current equal to or greater than a predetermined value) exceeding the rated current flows through the fuse element 50, and an active interruption mechanism in which, when an abnormality other than an overcurrent occurs, a current is passed through the heating element 80, causing it to generate heat, thereby melting the fuse element 50 and interrupting the current path.

[0037] (Definition of Directions) In this embodiment, an XYZ Cartesian coordinate system (three-dimensional Cartesian coordinate system) is appropriately set in each figure, and each configuration will be described. The predetermined direction in which the first terminal 91 and the second terminal 92 are aligned is referred to as the front-rear direction. The front-rear direction corresponds to the X-axis direction in each figure. Within the X-axis direction, the direction from the first terminal 91 to the second terminal 92 (-X side) is referred to as the front side, and the direction from the second terminal 92 to the first terminal 91 (+X side) is referred to as the rear side. Note that the front-rear direction is the direction connecting the first terminal 91 and the second terminal 92, and is also the direction in which electricity flows when the protection element 100 is in use, so it may also be referred to as the current flow direction.

[0038] The direction in which the plate surfaces of the first terminal 91 and the second terminal 92 face is referred to as the up-down direction. The up-down direction is a direction perpendicular to the front-rear direction and corresponds to the Z-axis direction in each drawing. In the up-down direction, the upper side corresponds to the +Z side, and the lower side corresponds to the -Z side.

[0039] The direction perpendicular to the front-rear direction and the up-down direction is called the left-right direction. The left-right direction corresponds to the Y-axis direction in each drawing. In the left-right direction, the left side corresponds to the -Y side, and the right side corresponds to the +Y side. Specifically, the -Y side is the left side when the protective element 100 is viewed from the rear (+X side), and the +Y side is the right side when the protective element 100 is viewed from the rear. The left-right direction may also be referred to as the width direction. In this case, for example, one side in the width direction corresponds to the -Y side, and the other side in the width direction corresponds to the +Y side.

[0040] In this embodiment, the terms "front side," "rear side," "upper side," "lower side," "left side," and "right side" are convenient names for clearly explaining the relative positional relationships of each component, and the actual positional relationships may be other than those indicated by these names.

[0041] (Insulating Case) As shown in Fig. 1, the insulating case 10 has an overall columnar shape extending in the front-to-rear direction. As shown in Figs. 1 and 2, the insulating case 10 has at least two (three in this embodiment) holding members 10B, 10C, and 10D stacked in the vertical direction, and a cylindrical cover 10A that houses these holding members 10B, 10C, and 10D. The at least two holding members 10B and 10C are arranged on both sides of the fuse element 50 in the vertical direction.

[0042] The plurality of holding members 10B, 10C, 10D include a first holding member 10B, a second holding member 10C, and a third holding member 10D.

[0043] The first holding member 10B is located at the lowest of the three holding members 10B, 10C, and 10D. The first holding member 10B is disposed below the first terminal 91, the second terminal 92, and the fuse element 50. The first holding member 10B has a generally cylindrical shape with a bottom that opens upward.

[0044] The first holding member 10B has a first accommodating portion 11, a terminal mounting surface 12, and a terminal locking portion 13. The first accommodating portion 11 is recessed downward from the top surface of the first holding member 10B. The first accommodating portion 11 is located in a middle portion of the first holding member 10B located between both end portions in the front-to-rear direction. The first accommodating portion 11 is a substantially rectangular hole that opens upward.

[0045] The terminal mounting surface 12 is concave and recessed downward from the top surface of the first holding member 10B. The bottom surface of the terminal mounting surface 12 is flat and faces upward, and extends in a plane direction perpendicular to the up-down direction (X-Y plane direction). A pair of terminal mounting surfaces 12 are provided on the first holding member 10B. The pair of terminal mounting surfaces 12 are located at both ends of the first holding member 10B in the front-to-rear direction.

[0046] The terminal locking portions 13 are arranged on side walls erected at the left-right ends of the first holding member 10B. The terminal locking portions 13 are groove-shaped and extend in the vertical direction, and open on the top surface of the first holding member 10B and on the wall surfaces facing inward (toward the center) in the left-right direction of the side walls. A pair of terminal locking portions 13 (i.e., a total of four) are provided on the front and rear portions of the first holding member 10B. The pair of terminal locking portions 13 are arranged facing each other with a gap between them in the left-right direction.

[0047] The second holding member 10C is located in the vertical center of the three holding members 10B, 10C, and 10D. The second holding member 10C is disposed above the first terminal 91, the second terminal 92, and the fuse element 50. The second holding member 10C has a cylindrical shape that extends vertically. Specifically, the second holding member 10C has a generally rectangular cylindrical shape that is open on both the top and bottom.

[0048] The second holding member 10C has a second accommodating portion 14 and a terminal pressing surface 15. The second accommodating portion 14 is recessed upward from the bottom surface of the second holding member 10C. The second accommodating portion 14 is located in a middle portion of the second holding member 10C located between both end portions in the front-to-rear direction. The second accommodating portion 14 is a substantially rectangular hole that opens downward.

[0049] The terminal pressing surface 15 is convex and protrudes downward from the underside of the second holding member 10C. The downward end surface of the terminal pressing surface 15 is flat and extends in a plane direction perpendicular to the up-down direction (X-Y plane direction). A pair of terminal pressing surfaces 15 are provided on the second holding member 10C. The pair of terminal pressing surfaces 15 are located at both ends of the second holding member 10C in the front-to-rear direction.

[0050] The third holding member 10D is located at the uppermost position among the three holding members 10B, 10C, and 10D. The third holding member 10D has a plate shape that extends in a plane direction perpendicular to the up-down direction.

[0051] The cover 10A is cylindrical and extends in the front-to-rear direction. Specifically, the cover 10A has a generally rectangular cylindrical shape with openings at the front and rear. The three holding members 10B, 10C, and 10D are housed inside the cover 10A in a combined, vertically aligned state. The cover 10A holds at least two (three in this embodiment) holding members 10B, 10C, and 10D in a fixed state by adhesive or the like.

[0052] When the first holding member 10B and the second holding member 10C are combined, the first housing portion 11 and the second housing portion 14 face each other to form a chamber (space) 18. A portion (front end) of the first terminal 91, a portion (rear end) of the second terminal 92, the fuse element 50, the insulating member 60, and the heating element 80 are arranged in this chamber 18. That is, the portion (front end) of the first terminal 91, the portion (rear end) of the second terminal 92, the fuse element 50, the insulating member 60, and the heating element 80 are arranged between the two holding members 10B and 10C.

[0053] The insulating case 10 also has an internal pressure buffering space 16 formed inside the insulating case 10. The internal pressure buffering space 16 is disposed inside the second holding member 10C. The internal pressure buffering space 16 is a substantially rectangular parallelepiped space and communicates with the chamber (space) 18. In this embodiment, the vertical dimension of the internal pressure buffering space 16 is, for example, between ⅓ and ½ of the vertical dimension (external height) of the entire protective element 100. The internal pressure buffering space 16 acts to suppress a sudden increase in the internal pressure of the protective element 100 due to gas generated by arc discharge that occurs when the fuse element 50 melts.

[0054] The cover 10A and each of the holding members 10B to 10D are preferably made of a material having a tracking resistance index (CTI) (resistance to tracking (carbonized conductive path) breakdown) of 500 V or more. The tracking resistance index (CTI) can be determined by a test based on IEC 60112.

[0055] Resin materials can be used as the material for the cover 10A and each of the holding members 10B to 10D. Resin materials have a smaller heat capacity and a lower melting point than ceramic materials. For this reason, using resin materials for the holding members 10B to 10D is preferable because it weakens the arc discharge caused by gasification cooling (ablation) and, when molten and scattered metal particles adhere to the holding members 10B to 10D, the surfaces of the holding members 10B to 10D deform or the adhesions aggregate, making the metal particles sparse and making it difficult to form a conduction path.

[0056] Examples of resin materials that can be used include polyamide-based resins and fluororesins. The polyamide-based resins may be aliphatic polyamides or semi-aromatic polyamides. Examples of aliphatic polyamides include nylon 4, nylon 6, nylon 46, and nylon 66. Examples of semi-aromatic polyamides include nylon 6T, nylon 9T, and polyphthalamide (PPA) resin. Examples of fluororesins include polytetrafluoroethylene. Furthermore, polyamide-based resins and fluororesins are highly heat-resistant and flammable. In particular, aliphatic polyamides are less likely to produce graphite when burned. Therefore, using aliphatic polyamides to form the cover 10A and each of the retaining members 10B-10D can more reliably prevent the formation of a new current path due to graphite generated by arc discharge when the fuse element 50 melts.

[0057] (First Terminal, Second Terminal) The first terminal 91 and the second terminal 92 each have a plate shape that extends in a plane direction (X-Y plane direction) perpendicular to the up-down direction, and specifically, are substantially rectangular plate shapes. The first terminal 91 and the second terminal 92 are arranged apart from each other in the front-rear direction.

[0058] 1 , the front end of the first terminal 91 is connected to the rear end of the fuse element 50. The rear portion of the first terminal 91 protrudes rearward from the insulating case 10 and is exposed to the outside of the insulating case 10. The rear end of the second terminal 92 is connected to the front end of the fuse element 50. The front portion of the second terminal 92 protrudes frontward from the insulating case 10 and is exposed to the outside of the insulating case 10.

[0059] The first terminal 91 and the second terminal 92 may have substantially the same shape or different shapes. The thickness dimensions (vertical dimensions) of the first terminal 91 and the second terminal 92 are not particularly limited, but may be, for example, several hundred μm to several mm. The thickness dimensions of the first terminal 91 and the second terminal 92 may be the same or different.

[0060] As shown in FIGS. 1 to 4, the first terminal 91 has a terminal body 91a, an external terminal hole 91b, a conductor connecting portion 91c, and a locking claw 91d.

[0061] The terminal body 91a is a rectangular plate that is long in the front-rear direction. The terminal body 91a is sandwiched between the terminal mounting surface 12 of the first holding member 10B and the terminal pressing surface 15 of the second holding member 10C. The external terminal hole 91b is a circular hole that penetrates the terminal body 91a in the vertical direction.

[0062] The conductor connecting portion 91c is disposed at the front end of the first terminal 91 and extends in the left-right direction. The conductor connecting portion 91c is disposed in a chamber (space) 18 defined by the first accommodating portion 11 and the second accommodating portion 14. The conductor connecting portion 91c has a larger vertical dimension than the terminal body 91a. In other words, the vertical dimension of the conductor connecting portion 91c is larger than the vertical dimension between the terminal mounting surface 12 and the terminal pressing surface 15.

[0063] The rear end of the fuse element 50 is connected to the conductor connection portion 91c by soldering or the like. The conductor connection portion 91c has a pair of connection plates 91e arranged at a distance from each other in the vertical direction. In this embodiment, a plurality of fuse elements 50 are provided, and the rear end of each fuse element 50 is connected to the respective connection plates 91e.

[0064] The locking claws 91d are disposed at the front end of the first terminal 91 and protrude in the left-right direction beyond the terminal body 91a. Specifically, the locking claws 91d protrude from the left and right ends of the conductor connecting portion 91c. When the first terminal 91 is assembled to the first holding member 10B, the locking claws 91d are inserted into the terminal locking portions 13. By locking the locking claws 91d with the terminal locking portions 13, the first terminal 91 is positioned in the front-rear direction relative to the first holding member 10B and movement in the front-rear direction is restricted.

[0065] The second terminal 92 has a terminal body 92a, an external terminal hole 92b, a conductor connecting portion 92c, and a locking claw 92d.

[0066] The terminal body 92a is a rectangular plate that is elongated in the front-to-rear direction. The terminal body 92a is sandwiched between the terminal mounting surface 12 of the first holding member 10B and the terminal pressing surface 15 of the second holding member 10C. The external terminal hole 92b is a circular hole that penetrates the terminal body 92a in the vertical direction.

[0067] The conductor connecting portion 92c is disposed at the rear end of the second terminal 92 and extends in the left-right direction. The conductor connecting portion 92c is disposed in a chamber (space) 18 defined by the first accommodating portion 11 and the second accommodating portion 14. The conductor connecting portion 92c has a larger vertical dimension than the terminal body 92a. In other words, the vertical dimension of the conductor connecting portion 92c is larger than the vertical dimension between the terminal mounting surface 12 and the terminal pressing surface 15.

[0068] The front end of the fuse element 50 is connected to the conductor connection portion 92c by soldering or the like. The conductor connection portion 92c has a pair of connection plates 92e arranged at a distance from each other in the vertical direction. In this embodiment, a plurality of fuse elements 50 are provided, and the front end of each fuse element 50 is connected to the respective connection plates 92e.

[0069] The locking claws 92d are disposed at the rear end of the second terminal 92 and protrude laterally beyond the terminal body 92a. Specifically, the locking claws 92d protrude from the left and right ends of the conductor connecting portion 92c. When the second terminal 92 is assembled to the first holding member 10B, the locking claws 92d are inserted into the terminal locking portions 13. By locking the locking claws 92d with the terminal locking portions 13, the second terminal 92 is positioned in the front-rear direction relative to the first holding member 10B and movement in the front-rear direction is restricted.

[0070] One of the pair of external terminal holes 91b, 92b is used for connection to the power supply side, and the other is used for connection to the load side, or the external terminal holes 91b, 92b may be used for connection to an internal current path of the load.

[0071] The first terminal 91 and the second terminal 92 are made of a metal such as copper, brass, or nickel. Brass is preferably used as the material for the first terminal 91 and the second terminal 92 from the viewpoint of increasing rigidity, and copper is preferably used from the viewpoint of reducing electrical resistance. The first terminal 91 and the second terminal 92 may be made of the same material or different materials.

[0072] 3 to 5, the fuse element 50 is formed of a metal plate-shaped member, sheet-shaped member, metal foil, or the like. In this embodiment, two fuse elements 50 are provided side by side in the vertical direction. However, the present invention is not limited to this, and only one fuse element 50 may be provided, or three or more fuse elements 50 may be provided side by side in the vertical direction.

[0073] The fuse element 50 has a fusible conductor 51 and a metal conductor 52 that connects the first terminal 91 or the second terminal 92 to the fusible conductor 51. The fusible conductor 51 is made of a material having a lower melting temperature than the metal conductor 52. In this embodiment, the fusible conductor 51 has a higher electrical resistivity than the metal conductor 52. In this embodiment, the fusible conductor 51 functions as a fusing portion of the fuse element 50 during both an overcurrent interruption and an active interruption.

[0074] The fusible conductor 51 is plate-shaped, sheet-shaped, or foil-shaped and extends in a plane direction (X-Y plane direction) perpendicular to the vertical direction. As shown in Figure 3, in this embodiment, the fusible conductor 51 is a rectangular plate-shaped member whose horizontal dimension is larger than its front-to-back dimension when viewed from the vertical direction. The fusible conductor 51 is disposed, for example, in the center of the fuse element 50 in the front-to-back direction.

[0075] Although not specifically shown, the soluble conductor 51 has a laminate in which a low-melting-point metal layer containing Sn (tin) and a high-melting-point metal layer containing Ag (silver) or Cu (copper) are laminated. This laminate has one or more low-melting-point metal layers and two or more high-melting-point metal layers, and the low-melting-point metal layers are arranged between the high-melting-point metal layers. This laminate is formed, for example, by coating the periphery of the low-melting-point metal layer with a high-melting-point metal layer.

[0076] The low-melting-point metal layer of the laminate may contain Sn, and may be Sn alone or an Sn alloy. An Sn alloy is an alloy containing Sn as the main component. That is, the low-melting-point metal layer is composed of Sn or Sn as the main component. An Sn alloy is an alloy with the highest Sn content among metals contained in alloys. Examples of Sn alloys include an Sn-Bi alloy, an In-Sn alloy, and an Sn-Ag-Cu alloy.

[0077] The high-melting-point metal layer of the laminate may contain Ag or Cu, and may be Ag alone, Cu alone, an Ag alloy, or a Cu alloy. An Ag alloy is an alloy with the highest Ag content among the metals contained in the alloy, and a Cu alloy is an alloy with the highest Cu content among the metals contained in the alloy. That is, the high-melting-point metal layer is composed of Cu or Ag, or Cu or Ag as the main component.

[0078] The laminate may have a two-layer structure of a low-melting-point metal layer / a high-melting-point metal layer. Alternatively, it may have a multilayer structure of three or more layers, including two or more high-melting-point metal layers, one or more low-melting-point metal layers, and the low-melting-point metal layers are arranged between the high-melting-point metal layers. The soluble conductor 51 may also be composed of a single layer of a low-melting-point metal layer containing Sn.

[0079] The metal conductor 52 is plate-shaped, sheet-shaped, or foil-shaped. As shown in Fig. 3 , in this embodiment, the metal conductor 52 has a generally rectangular plate shape in which the left-right dimension is longer than the front-rear dimension when viewed from the top-bottom direction. A plurality of metal conductors 52 are provided in the fuse element 50. The metal conductors 52 are arranged, for example, at both ends of the fuse element 50 in the front-rear direction.

[0080] 3 to 5, the plurality of metal conductors 52 include a first metal conductor 52A connecting the first terminal 91 and the first end (rear end) 51a of the soluble conductor 51, and a second metal conductor 52B connecting the second terminal 92 and the second end (front end) 51b of the soluble conductor 51. That is, in this embodiment, each fuse element 50 has a pair of metal conductors 52 (52A, 52B).

[0081] The first metal conductor 52A, the fusible conductor 51, and the second metal conductor 52B are connected in series in this order to form a current path of the fuse element 50. The metal conductors 52 are connected in pairs to both ends 51a, 51b of the fusible conductor 51 in the current flow direction of the fuse element 50 (approximately the front-to-rear direction in this embodiment).

[0082] In this embodiment, the first end 51a of the soluble conductor 51 is fixed on the front end of the first metal conductor 52A. That is, the lower surface of the first end 51a of the soluble conductor 51 and the upper surface of the front end of the first metal conductor 52A are connected. Also, the second end 51b of the soluble conductor 51 is fixed on the rear end of the second metal conductor 52B. That is, the lower surface of the second end 51b of the soluble conductor 51 and the upper surface of the rear end of the second metal conductor 52B are connected. The soluble conductor 51 is arranged on the upper side of the pair of metal conductors 52A and 52B and is suspended between them.

[0083] Each metal conductor 52 is made of Cu or Ag, or contains Cu or Ag as a main component.

[0084] 3 and 4 , the fuse element 50 further has a first bent portion 55 and a second bent portion 56. The first bent portion 55 is disposed between a portion of the fuse element 50 facing the insulating member 60 and the first terminal 91. In other words, the first bent portion 55 is disposed between the insulating member 60 and the first terminal 91 in the front-rear direction. Specifically, the first bent portion 55 is provided in the first metal conductor 52A.

[0085] In detail, the first metal conductor 52A has an inner plate portion 52a connected to the fusible conductor 51, an outer plate portion 52b connected to the first terminal 91, and a connecting plate portion 52c connecting the inner plate portion 52a and the outer plate portion 52b.

[0086] The inner plate portion 52a is a plate-like member that extends in a plane direction (X-Y plane direction) perpendicular to the vertical direction. The front end portion of the inner plate portion 52a is connected to the first end portion 51a of the fusible conductor 51 by soldering or the like. The outer plate portion 52b is a plate-like member that extends in a plane direction (X-Y plane direction) perpendicular to the vertical direction. The outer plate portion 52b is positioned rearward and above the inner plate portion 52a. The rear portion of the outer plate portion 52b is connected to the connection plate 91e of the conductor connection portion 91c by soldering or the like.

[0087] The connecting plate portion 52c is plate-shaped and extends in a plane direction perpendicular to the front-rear direction (Y-Z plane direction). The connecting plate portion 52c may also extend in a plane direction inclined relative to the Y-Z plane. That is, in a cross-sectional view perpendicular to the left-right direction (Y-axis direction) as shown in FIG. 4, the connecting plate portion 52c may extend along the up-down direction (Z-axis direction) or may extend at an angle relative to the up-down direction. The lower end of the connecting plate portion 52c is connected to the rear end of the inner plate portion 52a. The upper end of the connecting plate portion 52c is connected to the front end of the outer plate portion 52b.

[0088] The first bent portion 55 includes the connecting plate portion 52c, a bent connection portion (bent portion) between the connecting plate portion 52c and the inner plate portion 52a, and a bent connection portion (bent portion) between the connecting plate portion 52c and the outer plate portion 52b. The dimension L1 in the front-to-rear direction between the connecting plate portion 52c and the connecting plate 91e is greater than the dimension T1 in the up-down direction (i.e., the plate thickness dimension) of the connecting plate 91e. In other words, the distance in the front-to-rear direction between the first terminal 91 and the first bent portion 55 is greater than the thickness dimension of the first terminal 91 in the up-down direction.

[0089] The second bent portion 56 is disposed between the portion of the fuse element 50 facing the insulating member 60 and the second terminal 92. In other words, the second bent portion 56 is disposed between the insulating member 60 and the second terminal 92 in the front-rear direction. Specifically, the second bent portion 56 is provided in the second metal conductor 52B.

[0090] In detail, the second metal conductor 52B has an inner plate portion 52d connected to the fusible conductor 51, an outer plate portion 52e connected to the second terminal 92, and a connecting plate portion 52f connecting the inner plate portion 52d and the outer plate portion 52e.

[0091] The inner plate portion 52d is a plate-like member that extends in a plane direction (X-Y plane direction) perpendicular to the vertical direction. The rear end portion of the inner plate portion 52d is connected to the second end portion 51b of the fusible conductor 51 by soldering or the like. The outer plate portion 52e is a plate-like member that extends in a plane direction (X-Y plane direction) perpendicular to the vertical direction. The outer plate portion 52e is positioned forward and above the inner plate portion 52d. The front portion of the outer plate portion 52e is connected to the connection plate 92e of the conductor connection portion 92c by soldering or the like.

[0092] The connecting plate portion 52f is plate-shaped and extends in a plane direction perpendicular to the front-rear direction (Y-Z plane direction). The connecting plate portion 52f may also extend in a plane direction inclined relative to the Y-Z plane. That is, in a cross-sectional view perpendicular to the left-right direction (Y-axis direction) as shown in FIG. 4, the connecting plate portion 52f may extend along the up-down direction (Z-axis direction) or may extend at an angle relative to the up-down direction. The lower end of the connecting plate portion 52f is connected to the front end of the inner plate portion 52d. The upper end of the connecting plate portion 52f is connected to the rear end of the outer plate portion 52e.

[0093] The second bent portion 56 includes the connecting plate portion 52f, a bent connection portion (bent portion) between the connecting plate portion 52f and the inner plate portion 52d, and a bent connection portion (bent portion) between the connecting plate portion 52f and the outer plate portion 52e. The dimension L2 in the front-to-rear direction between the connecting plate portion 52f and the connecting plate 92e is greater than the dimension T2 (i.e., the plate thickness) of the connecting plate 92e in the up-down direction. In other words, the distance between the second terminal 92 and the second bent portion 56 in the front-to-rear direction is greater than the thickness of the second terminal 92 in the up-down direction.

[0094] At least one of the first bent portion 55 and the second bent portion 56 has a crank shape. In this embodiment, both the first bent portion 55 and the second bent portion 56 have a bent crank shape.

[0095] (Insulating Member) As shown in Figures 3 to 5, the insulating member 60 is plate-shaped, with a pair of plate surfaces facing the vertical direction. In this embodiment, the insulating member 60 is a rectangular plate whose left-right dimension is greater than its front-to-rear dimension when viewed from the vertical direction. The insulating member 60 is made of a resin with a tracking resistance index (CTI) of 500 V or more. The insulating member 60 is made of a polyamide-based resin material or a fluorine-based resin material. Examples of resin materials that make up the insulating member 60 are the same as those used for the insulating case 10 (cover 10A and each of holding members 10B to 10D) described above.

[0096] 4, the insulating member 60 is disposed facing the fuse element 50 from both the top and bottom sides. The insulating member 60 is disposed close to or in contact with the fuse element 50. The vertical dimension between the insulating member 60 and the fuse element 50 is, for example, 2 mm or less. The vertical dimension between the insulating member 60 and the fuse element 50 is preferably 1.5 mm or less, and more preferably 1 mm or less.

[0097] At least two insulating members 60 are provided above and below the fuse element 50. That is, at least a pair of insulating members 60 are arranged so as to sandwich the fuse element 50 from above and below. In this embodiment, two fuse elements 50 are provided side by side in the vertical direction, and insulating members 60 are provided above and below the upper fuse element 50 and above and below the lower fuse element 50, respectively.

[0098] More specifically, the insulating member 60 located below the upper fuse element 50 and the insulating member 60 located above the lower fuse element 50 are the same part (common part). For this reason, the fuse elements 50 and the insulating members 60 are arranged alternately in the vertical direction.

[0099] Furthermore, the insulating member 60 located below the lower fuse element 50 is formed integrally with the first holding member 10B. More specifically, the insulating member 60 located below the lower fuse element 50 is formed by a portion of the bottom wall 10a of the first holding member 10B. That is, at least one of the insulating members 60 is formed integrally with a portion of the insulating case 10. Although not specifically shown, the insulating member 60 located above the upper fuse element 50 may be formed integrally with the second holding member 10C. That is, one or both of the two holding members 10B, 10C are formed integrally with the insulating member 60.

[0100] The bottom wall 10a (insulating member 60) may also have a groove-shaped recess 19 recessed from the surface (upper surface) of the bottom wall 10a facing the fuse element 50. A pair of recesses 19 are provided in front of and behind the fusible conductor 51. The recesses 19 extend in the left-right direction. That is, the recesses 19 extend in a direction perpendicular to the current flow direction of the fuse element 50 (generally the front-rear direction in this embodiment, and partially including the up-down direction).

[0101] 3 to 5, the insulating member 60 has a heating element accommodating portion 61, a conductor-facing recess 62, a slit portion 63, and an air vent 64. The heating element accommodating portion 61 is recessed from the surface of the insulating member 60 facing the fuse element 50. In this embodiment, the heating element accommodating portion 61 is recessed upward from the lower surface, one of a pair of plate surfaces (upper and lower surfaces) of the insulating member 60 that faces the fuse element 50. In this embodiment, the heating element accommodating portion 61 is disposed in the center of the insulating member 60 in the front-to-rear direction. The heating element accommodating portion 61 is a rectangular hole that is long in the left-to-right direction.

[0102] The conductor-facing recess 62 is recessed from the surface of the insulating member 60 facing the fuse element 50. In the present embodiment, the conductor-facing recess 62 is recessed downward from the upper surface facing the fuse element 50, one of a pair of plate surfaces (upper and lower surfaces) of the insulating member 60. In the present embodiment, the conductor-facing recess 62 is disposed in the center of the insulating member 60 in the front-to-rear direction. Specifically, the conductor-facing recess 62 is disposed opposite the fusible conductor 51 of the fuse element 50. The dimension of the conductor-facing recess 62 in the front-to-rear direction is smaller than the dimension of the heating element accommodating portion 61 in the front-to-rear direction. The dimension (depth dimension) of the conductor-facing recess 62 in the up-down direction is smaller than the dimension of the heating element accommodating portion 61 in the up-down direction.

[0103] The insulating member 60 may also have a slit portion 63. The slit portion 63 is recessed from the surface of the insulating member 60 facing the fuse element 50 and pierces the insulating member 60. That is, the slit portion 63 is slit-shaped, penetrates the insulating member 60 in the vertical direction, and opens on each of a pair of plate surfaces (upper and lower surfaces). A pair of slit portions 63 is provided in front of and behind the fusible conductor 51. The slit portion 63 extends in the left-right direction. That is, the slit portion 63 extends in a direction perpendicular to the current flow direction of the fuse element 50 (generally the front-to-rear direction in this embodiment, and partially including the up-to-down direction). When the slit portion 63 is disposed in the insulating member 60, molten debris from the fuse element that adheres to the surface of the insulating member 60 facing the fuse element 50 after the fuse element 50 is interrupted becomes discontinuous at the slit portion 63, thereby suitably increasing the insulation resistance between the first terminal 91 and the second terminal 92 after the fuse element 50 is interrupted.

[0104] The ventilation holes 64 penetrate the insulating member 60 in the up-down direction. A plurality of ventilation holes 64 are provided in the insulating member 60. The plurality of ventilation holes 64 are arranged at both ends of the insulating member 60 in the left-right direction.

[0105] In this embodiment, the chamber 18 that houses the fuse element 50 communicates with the internal pressure buffering space 16 via the slit portion 63 and the vent hole 64. Therefore, if a pressure rise occurs in the chamber 18 due to the occurrence of an arc discharge when the fuse element 50 interrupts an overcurrent, this pressure can be efficiently released into the internal pressure buffering space 16 through the slit portion 63 and the vent hole 64.

[0106] (Heater) As shown in FIGS. 4 and 5 , the heater 80 is disposed so as to overlap the fuse element 50 in the vertical direction. The heater 80 contacts the fuse element 50 in the vertical direction. The heater 80 generates heat when current is applied from the power supply member 90, melting and blowing at least a portion of the fuse element 50. Specifically, the heater 80 is stacked vertically with the fusible conductor 51, and melts and blows at least a portion of the fusible conductor 51 due to heat generated by the current. In this embodiment, "melting and blowing at least a portion of the fuse element 50" may be abbreviated to "melting and blowing the fuse element 50." In addition, "melting and blowing at least a portion of the fusible conductor 51" may be abbreviated to "melting and blowing the fusible conductor 51." The same applies to the metal conductor 52. The same number of heaters 80 as the number of fuse elements 50 are provided. In this embodiment, two heaters 80 are provided, arranged vertically side by side. Each heating element 80 contacts a respective fuse element 50 .

[0107] 3 to 6B, the heating element 80 is plate-shaped, with a pair of plate surfaces facing in the vertical direction. In this embodiment, the heating element 80 is a rectangular plate-shaped element whose left-right dimension is greater than its front-rear dimension when viewed from the vertical direction. The heating element 80 is disposed in the heating element housing portion 61. In other words, the heating element 80 is housed in the insulating member 60.

[0108] The heating element 80 has an insulating substrate (substrate) 81, a resistive layer 82 laminated on the insulating substrate 81, a metal layer 83 laminated on the insulating substrate 81 and facing the fuse element 50 in the vertical direction, an insulating layer 84, and a heating element electrode 85. In this embodiment, the heating element 80 extends in the left-right direction, and the insulating substrate 81, the resistive layer 82, the metal layer 83, and the insulating layer 84 also extend in the left-right direction.

[0109] Specifically, the heating element 80 extends in a direction intersecting the current flow direction (generally the front-rear direction in this embodiment, and partially including the up-down direction) in which current flows through the fuse element 50, and in this embodiment, extends in a direction perpendicular to the current flow direction (i.e., the left-right direction). The insulating substrate 81, the resistive layer 82, the metal layer 83, and the insulating layer 84 also each extend in a direction intersecting the current flow direction, and in this embodiment, extend in a direction perpendicular to the current flow direction (the left-right direction).

[0110] In detail, as shown as an example in Figure 6B, the heating element 80 has two resistance layers 82 arranged at a distance in the front-to-back direction on the upper surface of an insulating substrate 81 and extending parallel to each other, an insulating layer 84 covering these resistance layers 82 from above, a pair of heating element electrodes 85 formed on the insulating substrate 81 and electrically connected to both ends of the resistance layers 82 in the left-right or front-to-back direction, and a metal layer 83 arranged on the lower surface of the insulating substrate 81 (see Figure 6A).

[0111] 6B , the heating element electrode 85 has a first electrode portion 85a extending in the front-rear direction and a second electrode portion 85b connected to the first electrode portion 85a and extending in the left-right direction. The first electrode portion 85a is disposed at the left-right end of the upper surface of the insulating substrate 81. At least a portion of the first electrode portion 85a is exposed to the outside of the heating element 80 without being covered by the insulating layer 84.

[0112] 6B , a pair of second electrode portions 85b are provided at a distance from each other in the front-rear direction in each heating electrode 85. Furthermore, the second electrode portions 85b of the pair of heating electrodes 85 are connected to both ends of the resistance layer 82 in the front-rear direction.

[0113] 5 and 6A, the metal layer 83 is disposed on one (the lower surface in this embodiment) of a pair of plate surfaces (upper and lower surfaces) of the insulating substrate 81, and the resistive layer 82 is disposed on the other (the upper surface in this embodiment) of the pair of plate surfaces. The metal layer 83 may also be referred to as an electrode (dummy electrode) or the like.

[0114] The resistive layer 82 is made of a conductive material that generates heat when a current is passed through it, such as nichrome, W, Mo, Ru, or a material containing any of these. The resistive layer 82 is formed by mixing a powder of an alloy, composition, or compound of these with a resin binder or the like to form a paste, which is then patterned on the insulating substrate 81 using a screen printing technique and then fired.

[0115] 6B , the resistance layer 82 is disposed on a portion of the insulating substrate (substrate) 81 in the front-to-rear direction. Specifically, the resistance layer 82 is disposed on the insulating substrate 81 at an end in the front-to-rear direction, and in this embodiment, a pair of resistance layers 82 is disposed on both ends in the front-to-rear direction of the upper surface of the insulating substrate 81. That is, a plurality of resistance layers 82 are provided on the insulating substrate 81 at intervals from each other in the front-to-rear direction. The dimension of the resistance layer 82 in the front-to-rear direction is half or less of the dimension of the insulating substrate 81 in the front-to-rear direction, and in this embodiment, is one-third or less.

[0116] The insulating substrate 81 is an insulating substrate made of, for example, alumina, glass ceramics, mullite, or zirconia. The insulating layer 84 is provided to protect the resistance layer 82. As the material for the insulating layer 84, for example, an insulating material such as ceramics or glass can be used. The insulating layer 84 can be formed by, for example, applying a paste of an insulating material and firing it. The insulating substrate 81 electrically insulates the heating element electrode 85 and resistance layer 82 on the upper surface of the heating element 80 from the metal layer 83 on the lower surface.

[0117] When it becomes necessary to cut off the electrical path due to an abnormality occurring in the external circuit that serves as the electrical path of the protective element 100, the heating element 80 is energized and generates heat by a current control element provided in the external circuit.

[0118] As shown in FIG. 5, a portion of the fusible conductor 51 of the fuse element 50 is disposed in a portion of the vertical gap G formed between the metal conductor 52 and the metal layer 83, and is sandwiched between the metal conductor 52 and the metal layer 83 in the vertical direction. The gap G is the same as or slightly larger than the vertical dimension (thickness dimension) of the fusible conductor 51, specifically, for example, several tens of μm to several hundred μm, and in this embodiment, it is approximately 50 μm to 100 μm. As described below, the gap G may be any dimension that can exhibit capillary action. In FIG. 5, the reference numeral 86 represents the solder 86 for mounting, and the reference numeral 87 represents the insulating flux. As shown in FIG. 5, the metal layer 83, the fusible conductor 51, and the metal conductor 52 are connected and fixed to each other by the solder 86.

[0119] 5 and 6A , a plurality of metal layers 83 are provided on the heating element 80. The plurality of metal layers 83 are spaced apart from one another in the front-to-rear direction. Each metal layer 83 faces a portion of the fuse element 50. The plurality of metal layers 83 includes a first metal layer 83A that is disposed with a first gap G1 in the vertical direction from the first metal conductor 52A, and a second metal layer 83B that is disposed with a second gap G2 in the vertical direction from the second metal conductor 52B. The first metal layer 83A is disposed at one end of the insulating substrate 81 in the front-to-rear direction, and the second metal layer 83B is disposed at the other end of the insulating substrate 81 in the front-to-rear direction. Specifically, in this embodiment, the first metal layer 83A is disposed at the rear end of the lower surface of the insulating substrate 81 in the front-to-rear direction, and the second metal layer 83B is disposed at the front end of the lower surface of the insulating substrate 81 in the front-to-rear direction.

[0120] The plurality of (two) resistance layers 82 provided on the upper surface of the insulating substrate 81 overlap with the first metal layer 83A and the second metal layer 83B when viewed from above and below. Therefore, when power is supplied from the power supply member 90 to the heating element electrode 85 and each resistance layer 82 generates heat, the heat is transferred to the first metal layer 83A and the second metal layer 83B via the insulating substrate 81, and these metal layers 83A and 83B are heated.

[0121] Note that, as in another example of a heating element 80 shown in FIG. 6C , only one resistive layer 82 may be provided on the insulating substrate 81. In this case, the single resistive layer 82 is arranged to overlap at least a portion of the first metal layer 83A and the second metal layer 83B when viewed from the top-bottom direction. Preferably, the single resistive layer 82 is arranged to overlap both the first metal layer 83A and the second metal layer 83B when viewed from the top-bottom direction. The single resistive layer 82 may be arranged across the entire upper surface of the insulating substrate 81. In the example shown in FIG. 6C , each heating element electrode 85 includes one second electrode portion 85b.

[0122] 5, the first end 51a of the soluble conductor 51 is arranged in a part of the first gap G1 and is sandwiched between the first metal conductor 52A and the first metal layer 83A in the vertical direction. The second end 51b of the soluble conductor 51 is arranged in a part of the second gap G2 and is sandwiched between the second metal conductor 52B and the second metal layer 83B in the vertical direction.

[0123] 7 shows a state in which a portion of the fuse element 50 has melted due to heat generated by the heating element 80 in response to a shutoff signal. The molten material 88 (including the first end 51a of the soluble conductor 51 and the solder 86) near the first end 51a of the soluble conductor 51, which has melted due to the heat generated by the heating element 80, penetrates the first gap G1 by capillary action and flows rearward. Furthermore, the molten material 89 (including the second end 51b of the soluble conductor 51 and the solder 86) near the second end 51b of the soluble conductor 51 penetrates the second gap G2 by capillary action and flows forward. As a result, the soluble conductor 51 is split in the front-to-rear direction and the fuse element 50 is deenergized. In other words, in this embodiment, the molten materials 88 and 89 of the soluble conductor 51, which have melted due to the heat generated by the heating element 80, penetrate the gap G by capillary action and flow, thereby melting the soluble conductor 51.

[0124] 5 and 6A , the multiple metal layers 83 further include an intermediate metal layer 83C disposed between the first metal layer 83A and the second metal layer 83B. The intermediate metal layer 83C is disposed between the first metal layer 83A and the second metal layer 83B in the front-to-rear direction. The dimension of the intermediate metal layer 83C in the front-to-rear direction is smaller than the dimension of the first metal layer 83A and smaller than the dimension of the second metal layer 83B in the front-to-rear direction. The intermediate metal layer 83C, the first metal layer 83A, and the second metal layer 83B are electrically insulated from the resistance layer 82.

[0125] The intermediate portion of the soluble conductor 51 located between the first end 51a and the second end 51b is connected to the intermediate metal layer 83C by solder 86. As shown in FIG. 7, when the heating element 80 generates heat due to a shutoff signal, the intermediate portion of the soluble conductor 51 located between the first end 51a and the second end 51b is maintained connected to the intermediate metal layer 83C. When the amount of heat generated by the heating element 80 is large, the soluble conductor 51 (the intermediate portion) connected to the intermediate metal layer 83C also melts, and a portion of the molten conductor 51 is retained on the surface of the intermediate metal layer 83C.

[0126] 8 shows a state in which a portion of the fuse element 50 has melted (disappeared) due to an overcurrent (current greater than or equal to a predetermined value) exceeding the rated current. As shown in FIG. 8, when a current greater than or equal to a predetermined value flows through the fuse element 50, at least a portion of the soluble conductor 51, or at least a portion of the soluble conductor 51 and at least a portion of the metal conductor 52, is melted, and the current through the fuse element 50 is cut off. In the example shown in FIG. 8, at least a portion of the soluble conductor 51 and at least a portion of the metal conductor 52 are melted. More specifically, all of the soluble conductor 51, the front end of the first metal conductor 52A, and the rear end of the second metal conductor 52B have disappeared due to the overcurrent.

[0127] (Power Supply Member) As shown in FIG. 2 , the power supply member 90 is a member that supplies power to the heating element 80. The power supply member 90 extends from the outside to the inside of the insulating case 10, and one end of the power supply member 90 is connected to the heating element electrode 85 of the heating element 80. Specifically, one end of the power supply member 90 is connected to the first electrode portion 85a of the heating element electrode 85. One end of the power supply member 90 and the first electrode portion 85a of the heating element electrode 85 are connected by, for example, solder. A part or all of the connection portion between the one end of the power supply member 90 and the first electrode portion 85a of the heating element electrode 85 may be fixed so as to be covered with an adhesive, and a part of the adhesive may also be adhered to the insulating member 60. This prevents the solder connecting the power supply member 90 and the first electrode portion 85a of the heating element electrode 85 from melting and cutting off the current before the fuse element 50 melts when current is applied to the heating element 80. In this embodiment, at least a portion of the power supply member 90 is made of an electric wire (wiring member). However, the present invention is not limited to this, and at least a portion of the power supply member may be made of a conductive plate-shaped member, rod-shaped member, or the like, although this is not particularly shown.

[0128] 4 , the protective element 100 includes a fuse element 50, a first terminal 91 and a second terminal 92 connected to both ends of the fuse element 50 in the current-carrying direction, and an insulating case 10 that accommodates portions of the first terminal 91 and the second terminal 92 and the fuse element 50. An element accommodating space 53 is formed in the insulating case 10 so that a portion of the insulating case 10 is in proximity to or in contact with at least a portion of the fuse element 50. The element accommodating space 53 is formed in a portion of a chamber (space) 18 that accommodates the fuse element 50 and is sandwiched between a portion of the insulating case 10 and an insulating member 60.

[0129] The rated voltage of the protective element 100 is equal to or less than the terminal distance D [mm] between the first terminal 91 and the second terminal 92 multiplied by the electric field strength of 30 [V / mm]. The rated voltage of the protective element 100 refers to the maximum voltage (applied voltage) that may be applied to the protective element 100. The terminal distance D corresponds to the distance between the first terminal 91 and the second terminal 92 in the X direction (the distance between the connecting plates 91e and 92e in the X direction) (see FIG. 4). The electric field strength is the value obtained by dividing the terminal voltage by the terminal distance D. According to the law of nature, reducing the electric field strength can reduce arc discharge. The rated voltage of the protective element 100 may be controlled by a control device (not shown) based on the terminal distance D [mm] between the first terminal 91 and the second terminal 92 and the electric field strength.

[0130] For example, the rated voltage of the protection element 100 may be equal to or greater than the value obtained by multiplying the inter-terminal distance D [mm] by the electric field strength of 15 [V / mm], or may be equal to or greater than the value obtained by multiplying the inter-terminal distance D [mm] by the electric field strength of 20 [V / mm]. Note that the lower limit of the rated voltage of the protection element 100 is not limited to the above and can be changed depending on the design specifications.

[0131] (Operation and Effect of the Present Embodiment) The protective element 100 of the present embodiment described above includes a fuse element 50, a first terminal 91 and a second terminal 92 connected to both ends of the fuse element 50 in the current-carrying direction, and an insulating case 10 that accommodates portions of the first terminal 91 and the second terminal 92 and the fuse element 50. The insulating case 10 has an element accommodating space 53 formed therein so that a portion of the insulating case 10 is in close proximity to or in contact with at least a portion of the fuse element 50. The rated voltage of the protective element 100 is equal to or less than the value obtained by multiplying the inter-terminal distance D [mm] between the first terminal 91 and the second terminal 92 by the electric field strength of 30 [V / mm]. As a result of extensive research, the present inventors have found that when the rated voltage of the protective element 100 is set, the effect of suppressing arc discharge that occurs when interrupting a high voltage and a large current varies depending on the inter-terminal distance D between the first terminal 91 and the second terminal 92. According to this configuration, the rated voltage of the protective element 100 is equal to or less than the terminal distance D [mm] multiplied by the electric field strength of 30 V / mm. This more effectively suppresses arc discharges that occur during high-voltage, high-current interruptions compared to when the rated voltage of the protective element 100 exceeds the terminal distance D [mm] multiplied by the electric field strength of 30 V / mm. This configuration allows for higher voltages by appropriately setting the terminal distance D according to the rated voltage of the protective element 100 and controlling the electric field strength, thereby suppressing arc discharges. Furthermore, this configuration narrows the space formed between a portion of the fuse element 50 and the insulating case 10. This minimizes the amount of gas around the fuse element 50, which is one of the sources of arc discharge that occurs during overcurrent interruptions. This suppresses plasma generated by ionization of gas, which is one of the sources of arc discharge, and thereby suppresses arc discharges. Additionally, there is no need to fill the fuse element 50 with silica sand, known as an arc-extinguishing agent, to suppress arc discharges. This prevents problems caused by continuous adhesion of molten debris to the surface of the arc-extinguishing agent (such as reduced interruption characteristics and reduced insulation resistance after interruption).This prevents arc discharge during interruption, makes it possible to interrupt high voltages and large currents, and prevents a decrease in insulation resistance after interruption.

[0132] Furthermore, in the protective element 100 of this embodiment, when an overcurrent exceeding the rated current (i.e., a current equal to or greater than a predetermined value) flows through the fuse element 50, the fuse element 50 generates heat and melts, thereby interrupting the current path. Alternatively, the protective element 100 can interrupt the current path by passing a current through the heating element 80 to generate heat, thereby melting and melting the fuse element 50 stacked on the heating element 80.

[0133] In this embodiment, the insulating member 60 is disposed facing the fuse element 50 from both the top and bottom sides. Specifically, the insulating member 60 approaches or contacts the fuse element 50 from above and below, and preferably is in close contact with the fuse element 50. This eliminates any space between the fuse element 50 and the insulating member 60 in which arc discharge can continue, ensuring that the arc discharge is extinguished when an overcurrent is interrupted.

[0134] As described above, according to this embodiment, it is possible to prevent a large-scale arc discharge from occurring when the fuse element 50 melts, and it is possible to provide a protection element 100 that can perform both an overcurrent cutoff function and a cutoff function in response to a cutoff signal.

[0135] In this embodiment, the fuse element 50 has a fusible conductor 51 stacked with the heating element 80 and a metal conductor 52 connecting the first terminal 91 or the second terminal 92 to the fusible conductor 51, and the fusible conductor 51 has a lower melting temperature than the metal conductor 52. In this case, the heating element 80 and the fusible conductor 51 with a low melting temperature are arranged overlapping each other, so that when current is applied to the heating element 80 to generate heat, the fusible conductor 51 melts and blows out stably. This makes it possible to more reliably interrupt the current path by the interruption signal.

[0136] In this embodiment, the soluble conductor 51 has a higher electrical resistivity than the metal conductor 52. In this case, when an overcurrent exceeding the rated current flows through the fuse element 50, the soluble conductor 51 having a high electrical resistivity becomes a heat spot, and the fuse element 50 is stably melted in the soluble conductor 51.

[0137] In this embodiment, the soluble conductor 51 has a laminate in which a low-melting-point metal layer containing Sn and a high-melting-point metal layer containing Ag or Cu are laminated, and this laminate has one or more low-melting-point metal layers and two or more high-melting-point metal layers, and the low-melting-point metal layers are arranged between the high-melting-point metal layers. In this case, since the high-melting-point metal layer is arranged on the outside of the laminate, the strength of the soluble conductor 51 is increased. When connecting the soluble conductor 51 to the metal conductor 52 or the heating element 80, deformation of the soluble conductor 51 due to heating during soldering is less likely to occur.

[0138] In this embodiment, the vertical dimension between the insulating member 60 and the fuse element 50 is 2 mm or less. In this case, the space formed between the fuse element 50 and the insulating member 60 is narrowed, which tends to reduce the scale of the arc discharge that occurs when the fuse element 50 melts due to an overcurrent interruption. In other words, a narrow melting space reduces the amount of gas in the space, and the amount of "plasma generated by ionizing the gas in the space," which serves as a path for current flow during the arc discharge, also decreases, making it easier to extinguish the arc discharge early. The above dimension is more preferably 1.5 mm or less, and even more preferably 1 mm or less.

[0139] In this embodiment, the insulating member 60 has a heating element accommodating portion 61, and the heating element 80 is disposed in the heating element accommodating portion 61. In this case, by accommodating the heating element 80 in the heating element accommodating portion 61, the portion of the surface of the insulating member 60 facing the fuse element 50 other than the heating element accommodating portion 61 can be disposed closer to or in contact with the fuse element 50. As a result, there is no space between the fuse element 50 and the insulating member 60 in which arc discharge can continue, and arc discharge is more reliably suppressed.

[0140] In this embodiment, the insulating member 60 has a slit portion 63 recessed from the surface of the insulating member 60 facing the fuse element 50 and penetrating the insulating member 60, or a groove-shaped recess 19 recessed from the top surface of the bottom wall 10a (corresponding to the lowest insulating member 60 among the multiple insulating members 60) facing the fuse element 50. The slit portion 63 or recess 19 extends in a direction perpendicular to the current flow direction of the fuse element 50. In this case, the provision of the slit portion 63 or recess 19 can prevent molten debris from being continuously formed on the surface of the insulating member 60 facing the fuse element 50 when the fuse element 50 melts due to an overcurrent interruption. This allows for a stable increase in insulation resistance after the current path is interrupted.

[0141] In this embodiment, at least two insulating members 60 are provided on the upper and lower sides of the fuse element 50, and at least one of the insulating members 60 is formed integrally with a part of the insulating case 10. Specifically, the insulating member 60 is integrated with the holding member 10B (part of the insulating case 10). This reduces the number of parts, facilitating the manufacture of the protection element 100 and reducing manufacturing costs.

[0142] In this embodiment, the insulating case 10 has an internal pressure buffering space 16 formed inside the insulating case 10 and communicating with a chamber (space) 18 in which the fuse element 50 is disposed. In this case, the internal pressure buffering space 16 can suppress a sudden increase in the internal pressure of the protective element 100 caused by gas generated by an arc discharge that occurs when the fuse element 50 melts. This prevents damage to the insulating case 10.

[0143] In this embodiment, a portion of the soluble conductor 51 is disposed in a portion of the vertical gap G formed between the metal conductor 52 and the metal layer 83, and is sandwiched between the metal conductor 52 and the metal layer 83 in the vertical direction. In this case, the resistance layer (heater) 82 generates heat when energized, and this heat is transmitted to the metal layer (dummy electrode) 83 via the insulating substrate (heater substrate) 81, and a portion of the soluble conductor 51 melts between the metal layer 83 and the metal conductor 52. The shut-off signal allows the soluble conductor 51 to be efficiently melted and reliably blown out.

[0144] In this embodiment, the molten materials 88 and 89 of the soluble conductor 51 melted by the heat generated by the heating element 80 flow while penetrating into the gap G due to capillary action, thereby melting the soluble conductor 51. In this case, the molten materials 88 and 89 of the soluble conductor 51 are sucked into the gap G between the metal conductor 52 and the metal layer 83 due to capillary action, causing the molten materials 88 and 89 to flow in the desired direction, thereby more reliably melting the soluble conductor 51.

[0145] In this embodiment, specifically, the first end 51a of the soluble conductor 51 is arranged in a portion of the first gap G1 and is sandwiched between the first metal conductor 52A and the first metal layer 83A in the vertical direction, and the second end 51b of the soluble conductor 51 is arranged in a portion of the second gap G2 and is sandwiched between the second metal conductor 52B and the second metal layer 83B in the vertical direction. In this case, due to the heat generated by the heating element 80, the vicinity of the first end 51a of the soluble conductor 51 is melted between the first metal layer 83A and the first metal conductor 52A, and the vicinity of the second end 51b of the soluble conductor 51 is melted between the second metal layer 83B and the second metal conductor 52B. Since the soluble conductor 51 is melted at both ends in the current-carrying direction, the fuse element 50 can be more reliably melted by a cutoff signal.

[0146] In this embodiment, specifically, the molten material 88 near the first end 51a of the soluble conductor 51 melted by the heat generated by the heating element 80 flows while penetrating into the first gap G1 due to capillary action, and the molten material 89 near the second end 51b of the soluble conductor 51 flows while penetrating into the second gap G2 due to capillary action, thereby melting the soluble conductor 51. In this case, the molten materials 88 and 89 of the soluble conductor 51 flow while being sucked in by capillary action near both ends in the current-carrying direction, so that the soluble conductor 51 is more reliably melted.

[0147] In this embodiment, the plurality of metal layers 83 further includes an intermediate metal layer 83C, and the intermediate portion of the soluble conductor 51 located between the first end 51a and the second end 51b is connected to the intermediate metal layer 83C. In the above configuration, even if the soluble conductor 51 is blown out near both ends in the current-carrying direction as described above, the intermediate portion of the soluble conductor 51 is maintained in a state held by the intermediate metal layer 83C. This allows the soluble conductor 51 to be blown out more reliably.

[0148] Specifically, by providing the intermediate metal layer 83C, the fusible conductor 51 after melting is divided into three parts: a part 88 (near the first end 51a) arranged in the first gap G1, a part 89 (near the second end 51b) arranged in the second gap G2, and a part (near the middle part) held by the intermediate metal layer 83C. By dividing the fusible conductor 51 into three divided bodies, the volume (volume) of each divided body is reduced, the amount of melting is also reduced, and the flow of the molten material is easier to control.

[0149] More specifically, for example, the molten material of the soluble conductor 51 may gather near the center of the soluble conductor 51 in the left-right direction due to the action of surface tension, creating an unintended lump, or may flow while rotating in the X-Y plane, causing the current flowing through the soluble conductor 51 to become unstable. This can be suppressed by the intermediate metal layer 83C of this embodiment.

[0150] In this embodiment, the heating element 80 has an insulating substrate 81, a resistive layer 82 laminated on the insulating substrate 81, and a metal layer 83 laminated on the insulating substrate 81 and facing a part of the fuse element 50, and the resistive layer 82 extends in a direction (left-right direction in this embodiment) that intersects the current flow direction in the fuse element 50, and is positioned in a part of the front-to-back direction on the insulating substrate 81.

[0151] In this case, the resistance layer (heater) 82 generates heat when energized, and this heat is transferred to the metal layer (dummy electrode) 83 via the insulating substrate (heater substrate) 81, melting a portion of the fuse element 50 facing the metal layer 83 (in this embodiment, the fusible conductor 51 melts). When the heating element 80 generates heat in response to a shutoff signal, a portion of the fuse element 50 can be efficiently melted and blown.

[0152] The resistive layer 82 is disposed on a portion of the insulating substrate 81 in the front-to-rear direction (X-axis direction). This makes it possible to minimize the thermal load that the insulating substrate 81 receives when the resistive layer 82 generates heat. This makes it possible to stably prevent problems such as the insulating substrate 81 being broken due to a large thermal load.

[0153] In this embodiment, the resistance layer 82 is disposed at the front-rear end of the insulating substrate 81. In this case, the heat load on the insulating substrate 81 due to the heat generated by the resistance layer 82 is kept small, and the heated area is concentrated at the end of the insulating substrate 81, thereby efficiently melting a portion of the fuse element 50 and reliably blowing it.

[0154] In this embodiment, the dimension of the resistance layer 82 in the front-to-rear direction is equal to or less than half the dimension of the insulating substrate 81 in the front-to-rear direction. In this case, the thermal load that the insulating substrate 81 receives due to heat generation by the resistance layer 82 can be stably kept small. More preferably, the dimension of the resistance layer 82 in the front-to-rear direction is equal to or less than one-third of the dimension of the insulating substrate 81 in the front-to-rear direction.

[0155] In this embodiment, a plurality of resistive layers 82 are provided at intervals in the front-to-rear direction on the insulating substrate 81. In this case, the heat generated by each resistive layer 82 can more reliably melt the fuse element 50, and the thermal load on the insulating substrate 81 can be kept small.

[0156] In this embodiment, the fuse element 50 has a first bent portion 55 disposed between the first terminal 91 and the insulating member 60 in the front-rear direction, and a second bent portion 56 disposed between the second terminal 92 and the insulating member 60 in the front-rear direction, wherein a distance D1 between the first terminal 91 and the first bent portion 55 in the front-rear direction is greater than a thickness dimension T1 of the first terminal 91 in the up-down direction, and a distance D2 between the second terminal 92 and the second bent portion 56 in the front-rear direction is greater than a thickness dimension T2 of the second terminal 92 in the up-down direction. In this embodiment, a configuration is adopted in which the fuse element 50 is sandwiched between the insulating members 60 from above and below, thereby minimizing air in the space (interruption space) around the melted portion of the fuse element 50 and suppressing the amount of air plasma generated, which serves as a path for arc discharge during overcurrent interruption. However, on the other hand, if the distance between the first terminal 91 and the second terminal 92 in the front-to-rear direction changes due to thermal expansion or thermal contraction caused by a change in the ambient temperature where the protective element 100 is installed, the fuse element 50 may not be able to adequately follow this change, resulting in a disconnection. Particularly in this embodiment, the first terminal 91 and the second terminal 92 are positioned by the resin holding member 10B, and may be susceptible to thermal expansion or thermal contraction caused by a change in the temperature of the holding member 10B, or may be affected by a change in the position of a member such as a bus bar outside the protective element 100 to which the first terminal 91 and the second terminal 92 are connected.

[0157] In this regard, in the present embodiment, the fuse element 50 is provided with the first bent portion 55 and the second bent portion 56, so that even if the distance between the first terminal 91 and the second terminal 92 in the front-to-rear direction changes due to a change in the ambient temperature where the protection element 100 is installed, the first bent portion 55 and the second bent portion 56 can expand and contract the dimension of the fuse element 50 in the front-to-rear direction. In other words, the simple structure allows the fuse element 50 to follow changes in the distance between the terminals 91 and 92.

[0158] Specifically, the distance D1 in the front-to-rear direction between the first terminal 91 and the first bent portion 55 is set to be larger than the thickness dimension T1 in the up-down direction of the first terminal 91. Therefore, even if the solder connecting the fuse element 50 and the first terminal 91 protrudes from the first terminal 91 toward the fuse element 50, it is prevented from reaching the first bent portion 55. This prevents the first bent portion 55 and the first terminal 91 from being fixed to each other, and the expansion and contraction function of the fuse element 50 due to the first bent portion 55 is stably achieved.

[0159] Furthermore, the distance D2 in the front-to-rear direction between the second terminal 92 and the second bent portion 56 is set to be larger than the thickness dimension T2 in the up-down direction of the second terminal 92. Therefore, even if the solder connecting the fuse element 50 and the second terminal 92 protrudes from the second terminal 92 toward the fuse element 50, it is prevented from reaching the second bent portion 56. This prevents the second bent portion 56 and the second terminal 92 from being fixed to each other, and the second bent portion 56 allows the expansion and contraction function of the fuse element 50 to be stably achieved.

[0160] Therefore, according to this embodiment, it is possible to suppress the occurrence of a large-scale arc discharge when the fuse element 50 melts, while reliably preventing problems such as the fuse element 50 being subjected to excessive loads such as tension or compression due to temperature changes, etc., causing the fuse element 50 to break.

[0161] In this embodiment, at least one of the first bent portion 55 and the second bent portion 56 has a crank shape. In this case, the expansion and contraction function of the fuse element 50 due to the first bent portion 55 or the second bent portion 56 is more stably achieved.

[0162] Furthermore, in this embodiment, the insulating case 10 has at least two holding members 10B, 10C arranged on both sides of the fuse element 50 in the vertical direction, and a portion of the first terminal 91, a portion of the second terminal 92, and the fuse element 50 are arranged between the two holding members 10B, 10C, and one or both of the two holding members 10B, 10C are formed integrally with the insulating member 60. In this case, the insulating member 60 is integrated with a portion of the insulating case 10. This reduces the number of parts, facilitating the manufacture of the protection element 100 and reducing manufacturing costs.

[0163] In this embodiment, the insulating case 10 has a cover 10A that houses at least two holding members 10B-10D, and the cover 10A holds the at least two holding members 10B-10D in a fixed state. In this case, by housing the multiple holding members 10B-10D in the cover 10A, these holding members 10B-10D are maintained in a fixed state with respect to one another. The postures of a portion of the first terminal 91, a portion of the second terminal 92, and the fuse element 50, which are arranged between the multiple holding members 10B and 10C, are stabilized.

[0164] In this embodiment, the insulating member 60 is made of a resin having a tracking resistance index CTI of 500 V or more. In this case, arc discharge makes it difficult for carbides that serve as conductive paths to be formed on the surface of the insulating member 60, making it even more difficult for leakage current to occur.

[0165] In this embodiment, the insulating member 60 is made of a polyamide-based resin material or a fluorine-based resin material. Resin materials have a smaller heat capacity and a lower melting point than, for example, ceramic materials. Using a resin material as the material for the insulating member 60, as in this embodiment, is preferable because it weakens arc discharge caused by gasification cooling (ablation) and, when molten and scattered metal particles adhere to the insulating member 60, the surface of the insulating member 60 deforms or the adhered particles aggregate, making the metal particles sparse and making it difficult to form a conduction path.

[0166] The present invention is not limited to the above-described embodiment, and the configuration may be modified within the scope of the present invention, as described below. In the illustrations of the modified examples, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the following mainly describes the differences.

[0167] In the above-described embodiment, an example was given in which the fuse element 50 has a fusible conductor 51 and a metal conductor 52 made of different materials, but this is not limited to this. The fuse element 50 may be entirely made of Cu or Ag, or may be made mainly of Cu or Ag. In this case, the fuse element 50 contains Cu or Ag. The fuse element 50 may be made of Cu alone, Ag alone, a Cu alloy, or an Ag alloy.

[0168] According to the above configuration, the electrical resistivity of the fuse element 50 is likely to be lower than when the fuse element 50 is a laminate of a high-melting-point metal layer and a low-melting-point metal layer. Therefore, a fuse element 50 made of a single layer containing Cu or Ag can be made thinner even when it has the same electrical resistance as a fuse element 50 made of a laminate of a high-melting-point metal layer and a low-melting-point metal layer in the same area. If the fuse element 50 is thinner, the amount of molten material that splashes when the fuse element 50 melts is reduced in proportion to the thickness, resulting in higher insulation resistance after interruption.

[0169] (Protective element (first modified example)) FIG. 9 is a perspective view (cross-sectional perspective view) showing the appearance and cross section of a protective element 110 of a first modified example. In this first modified example, the vertical dimension of the internal pressure buffering space 16 is smaller than that of the protective element 100 described in the above embodiment. Specifically, the vertical dimension of the internal pressure buffering space 16 of the first modified example is, for example, 1 / 5 to 1 / 3 of the vertical dimension (external height) of the entire protective element 110. In this way, by appropriately setting the vertical dimension of the internal pressure buffering space 16, it is possible to make the protective element 110 more compact.

[0170] (Protective Element (Second Modification)) FIG. 10 is a perspective view (cross-sectional perspective view) showing the appearance and cross section of a protective element 120 of a second modification. In this second modification, an internal pressure buffering space 16 is not provided inside the insulating case 10. Furthermore, the insulating case 10 does not have a third holding member 10D. If the sudden increase in internal pressure of the protective element 120 due to gas generated by an arc discharge that occurs when the fuse element 50 melts can be sufficiently suppressed by a chamber (space) 18 or the like, it is possible to configure the protective element 120 without providing the internal pressure buffering space 16 as described above. In this case, the protective element 120 can be made even more compact.

[0171] (Protection element (third modified example)) Figure 11 is a cross-sectional view showing a part of the protection element 130 of the third modified example. In this third modified example, the heating element 80 is arranged below the soluble conductor 51 and is connected to the lower surface of the soluble conductor 51. This third modified example also provides the same effects as those of the above-mentioned embodiment.

[0172] (Protective element (fourth modified example)) Figures 12 and 13 are cross-sectional views showing a part of the protective element 140 of the fourth modified example. As shown in Figure 12, in this fourth modified example, the insulating member 60 has a concave conductor-facing recess 62 recessed upward from the surface (lower surface) facing the fuse element 50 of the insulating member 60. As shown in Figure 13, when the heating element 80 generates heat due to a shutoff signal, at least a part of the fusible conductor 51M (51) melted by this heat generation is arranged in the conductor-facing recess 62.

[0173] In this case, at least a portion of the molten soluble conductor 51M is accommodated in the conductor facing recess 62, thereby promoting the action of the surface tension of the soluble conductor 51M, and the soluble conductor 51M can be stably separated from the metal conductor 52. This allows the conduction (circuit) between the soluble conductor 51M (51) and the metal conductor 52 to be stably interrupted.

[0174] (Protective element (fifth modified example)) FIG. 14 is a cross-sectional view showing a part of the protective element 150 of the fifth modified example. As shown in FIG. 14, in this fifth modified example, the metal conductor 52A (52) has an interrupting portion 52g having a higher electrical resistance than the fusible conductor 51. In this case, when an overcurrent exceeding the rated current flows through the fuse element 50, the interrupting portion 52g of the metal conductor 52A having a high electrical resistance becomes a heat spot, and the fuse element 50 is stably melted at the interrupting portion 52g.

[0175] Since the interruption point due to the interruption signal (the fusible conductor 51) and the interruption point due to the overcurrent interruption (the interruption part 52g) can be provided separately, it is possible to arrange the insulating member 60 closer to or in contact with the interruption part 52g from above and below, as shown in Figure 14. Therefore, the arc discharge that occurs when the interruption part 52g melts can be extinguished more quickly and reliably.

[0176] More specifically, in this fifth modified example, the cross-sectional area of ​​the cutoff portion 52g in a cross section (Y-Z cross section) perpendicular to the current flow direction (front-back direction) is smaller than the cross-sectional area of ​​the portion of the metal conductor 52 other than the cutoff portion 52g. In the illustrated example, the vertical dimension (thickness dimension) of the cutoff portion 52g is smaller than the vertical dimension of the portion of the metal conductor 52 other than the cutoff portion 52g. In this case, with a simple structure, the electrical resistance of the cutoff portion 52g can be made higher than the electrical resistance of the other portions of the metal conductor 52, thereby ensuring that the cutoff portion 52g is melted down.

[0177] (Protective Element (Sixth Modification)) FIG. 15 is a top view showing a portion (fuse element 50) of a protective element 160 of a sixth modification. As shown in FIG. 15, in this sixth modification, the interrupter 52g has a plurality of through holes 52h that penetrate the metal conductor 52 in the up-down direction. As a result, the cross-sectional area of ​​the interrupter 52g in a cross section (Y-Z cross section) perpendicular to the current flow direction (front-back direction) is smaller than the cross-sectional area of ​​the metal conductor 52 other than the interrupter 52g. With this configuration, it is possible to obtain the same effects as those described above.

[0178] (Protective Element (Seventh Modification)) FIG. 16 is a top view showing a portion (fuse element 50) of a protective element 170 of a seventh modification. As shown in FIG. 16, in this seventh modification, the interrupter 52g has a plurality of notches 52i that cut out portions of the metal conductor 52. As a result, the cross-sectional area of ​​the interrupter 52g in a cross section (Y-Z cross section) perpendicular to the current flow direction (front-rear direction) is smaller than the cross-sectional area of ​​the metal conductor 52 other than the interrupter 52g. This configuration can also achieve the same effects as those described above. Furthermore, the interrupter 52g of the metal conductor 52 may be provided at a plurality of locations in the current flow direction through the fuse element 50.

[0179] (Protection element (eighth modified example)) Figure 17 is a cross-sectional view showing a part of the protection element 180 of the eighth modified example. As shown in Figure 17, in this eighth modified example, the heating element 80 is arranged on the upper and lower sides of the soluble conductor 51. That is, the heating element 80 is provided on both sides of the fuse element 50 in the vertical direction.

[0180] In this case, the pair of heating elements 80 arranged to sandwich the fuse element 50 from above and below ensures that the fuse element 50 melts and blows during active interruption.

[0181] (Protective Element (Ninth Modification)) Figure 18 is a top view showing a part (heating element 80) of a protective element of the ninth modification. As shown in Figure 18, in this ninth modification, the heating element 80 has one resistive layer 82. The resistive layer 82 is arranged on a part of the insulating substrate 81 in the front-to-rear direction, and more specifically, is arranged on the front-to-rear end of the upper surface of the insulating substrate 81. Furthermore, each of the pair of heating element electrodes 85 has one first electrode portion 85a and one second electrode portion 85b extending in the left-to-right direction from the first electrode portion 85a. This ninth modification can also achieve the same effects as those described above.

[0182] (Protective Element (Tenth Modification)) FIG. 19 is a top view showing a part (heating element 80) of a protective element of a tenth modification. As shown in FIG. 19, in this tenth modification, the heating element 80 has a plurality of resistive layers 82, specifically three. The three resistive layers 82 are arranged on the upper surface of the insulating substrate 81, at both ends in the front-to-rear direction and in a middle portion located between the ends. Each of the pair of heating element electrodes 85 has one first electrode portion 85a and three (multiple) second electrode portions 85b extending in the left-right direction from the first electrode portion 85a and arranged side by side in the front-to-rear direction. This tenth modification can also achieve the same effects as those described above.

[0183] (Protective element (eleventh modified example)) Figure 20 is a perspective view showing a part (heating element 80) of the protective element of the eleventh modified example. As shown in Figure 20, in the eleventh modified example, the heating element 80 does not have an intermediate metal layer 83C. For example, if the heat generation amount of the resistance layer 82 (heating element 80) is large and the part of the soluble conductor 51 connected to the intermediate metal layer 83C (the middle part in the front-to-back direction of the soluble conductor 51) is all melted when current is applied to the resistance layer 82, the function of the intermediate metal layer 83C (the function of holding part of the soluble conductor 51) may not be fully obtained. In such a case, the manufacturing cost of the heating element 80 may be reduced by not providing the intermediate metal layer 83C as in the above configuration.

[0184] (Protective Element (Twelfth Modification)) Fig. 21 is a perspective view showing a part (heating element 80) of a protective element of the twelfth modification. As shown in Fig. 21, in the twelfth modification, the heating element 80 has a retaining metal layer 93 laminated on an insulating substrate 81. The retaining metal layer 93 faces the fuse element 50 in the vertical direction. Specifically, the retaining metal layer 93 is arranged on the same plate surface (the lower surface in the illustrated example) as the plate surface on which the metal layer 83 is arranged, of a pair of plate surfaces facing the vertical direction of the insulating substrate 81.

[0185] The holding metal layer 93 is made of the same material as the metal layer 83. The holding metal layer 93 and the metal layer 83 are formed on the insulating substrate 81, for example, by the same printing process. The holding metal layer 93 is connected to one of the multiple metal layers 83. Specifically, the holding metal layer 93 is connected to the first metal layer 83A or the second metal layer 83B, and in the illustrated example, it is connected to the first metal layer 83A. That is, the holding metal layer 93 is formed integrally with the metal layer 83. The holding metal layer 93 is connected to the end of the metal layer 83 in a direction (left-right direction) that intersects the current flow direction of the fuse element 50. The holding metal layer 93 is capable of holding the molten material of the fuse element 50. Note that, in this specification, the "molten material of the fuse element 50" includes not only the molten material of the fusible conductor 51 but also the molten material of the mounting solder 86. The molten material may also be referred to as a solder puddle, etc.

[0186] The holding metal layer 93 protrudes from the left-right ends of the first metal layer 83A (metal layer 83). Specifically, the holding metal layer 93 protrudes from the left-right ends of the first metal layer 83A toward the outside in the left-right direction of the heating element 80 (opposite the center in the left-right direction) and toward the inside in the front-rear direction of the heating element 80 (toward the center in the front-rear direction). In the illustrated example, a pair of holding metal layers 93 are provided spaced apart from each other in the left-right direction. The pair of holding metal layers 93 are connected to both left-right ends of the first metal layer 83A. The pair of holding metal layers 93 are arranged at both left-right ends of the plate surface of the insulating substrate 81 facing the fuse element 50, and each extend in the front-rear direction.

[0187] According to the twelfth modification, when heat from the resistance layer 82 is transferred to the metal layer 83 and a portion of the fuse element 50 melts, the following effect is obtained. That is, even if the molten material of the fuse element 50 flows along the metal layer 83 in the direction in which the metal layer 83 extends (the left-right direction) and accumulates near an end of the metal layer 83, the molten material is retained by the retaining metal layer 93 connected to this end. The retaining metal layer 93 can stably retain the molten material in a predetermined position and can control the flow of the molten material, thereby stably preventing problems such as the molten material interfering with the interruption of current flow (active interruption).

[0188] Specifically, in the twelfth modification, the holding metal layer 93 is connected to the first metal layer 83A or the second metal layer 83B. In this case, even if the molten material of the fuse element 50 accumulates near the end of the first metal layer 83A in the extension direction (left-right direction) or near the end of the second metal layer 83B in the extension direction, the molten material can be stably held by the holding metal layer 93 connected to this end.

[0189] (Protective Element (Thirteenth Modification)) FIG. 22 is a perspective view showing a part (heating element 80) of a protective element of the thirteenth modification. As shown in FIG. 22 , the holding metal layer 93 may be connected to the intermediate metal layer 83C. Specifically, the holding metal layer 93 protrudes from the left-right ends of the intermediate metal layer 83C toward the outside in the left-right direction of the heating element 80 (the opposite side from the center in the left-right direction), and also toward the outside in the front-rear direction of the heating element 80 (the opposite side from the center in the front-rear direction). In the illustrated example, a pair of holding metal layers 93 are provided spaced apart from each other in the left-right direction. The pair of holding metal layers 93 are connected to both left-right ends of the intermediate metal layer 83C. Furthermore, the holding metal layer 93 may be connected to the first metal layer 83A or the second metal layer 83B.

[0190] According to the thirteenth modification, even if the molten material of the fuse element 50 accumulates near the end of the intermediate metal layer 83C in the extension direction (left-right direction), the molten material can be stably held by the holding metal layer 93 connected to this end. Furthermore, when the holding metal layer 93 is connected to the first metal layer 83A or the second metal layer 83B, even if the molten material of the fuse element 50 accumulates near the end of the first metal layer 83A in the extension direction (left-right direction) or near the end of the second metal layer 83B in the extension direction, the molten material can be stably held by the holding metal layer 93 connected to this end. That is, the holding metal layer 93 is connected to one of the intermediate metal layer 83C, the first metal layer 83A, and the second metal layer 83B. More specifically, the holding metal layer 93 is connected to one or more (i.e., at least one) of the intermediate metal layer 83C, the first metal layer 83A, and the second metal layer 83B.

[0191] (Protective Element (Fourteenth Modification)) FIG. 23 is a cross-sectional view showing a portion of a protective element of a fourteenth modification, and corresponds to a portion of the cross-sectional view shown in FIG. 4 . As shown in FIG. 23 , in the fourteenth modification, of the multiple insulating members 60 included in the protective element, the insulating member 60 facing the upper fuse element 50 from below has an accommodating through-hole 67 (accommodating recess 69). The accommodating through-hole 67 penetrates the insulating member 60 in the up-down direction and has, for example, a substantially rectangular hole shape. The accommodating through-hole 67 is connected to the left-right ends of the slit portion 63 of the insulating member 60. A pair of accommodating through-holes 67 is provided in the insulating member 60, spaced apart from each other in the left-right direction. The pair of accommodating through-holes 67 is connected to both left-right ends of the slit portion 63.

[0192] The accommodating through-hole 67 (accommodating recess 69) is disposed directly below the retaining metal layer 93 of the upper heating element 80 of the pair of heating elements 80 provided in the protective element. In other words, the accommodating through-hole 67 faces the retaining metal layer 93. The accommodating through-hole 67 can accommodate the molten material of the fuse element 50 retained by the retaining metal layer 93.

[0193] Furthermore, among the multiple insulating members 60 included in the protective element, the insulating member 60 facing the lower fuse element 50 from below has an accommodating hole 68 (accommodating recess 69). More specifically, the insulating member 60 facing the lower fuse element 50 from below is formed by a portion of the bottom wall 10a of the first holding member 10B, and this bottom wall 10a has an accommodating hole 68 recessed from the upper surface of the bottom wall 10a. The accommodating hole 68 is connected to the left and right ends of a groove-shaped recess 19 provided in the bottom wall 10a. A pair of accommodating holes 68 are provided in the bottom wall 10a, spaced apart from each other in the left and right direction. The pair of accommodating holes 68 are connected to both left and right ends of the recess 19.

[0194] The accommodating hole 68 (accommodating recess 69) is disposed directly below the retaining metal layer 93 of the lower heating element 80 of the pair of heating elements 80 provided in the protective element. In other words, the accommodating hole 68 faces the retaining metal layer 93. The accommodating hole 68 can accommodate the molten material of the fuse element 50 retained by the retaining metal layer 93.

[0195] Although not specifically shown, the molten material of the fuse element 50 held by the holding metal layer 93 has, for example, a droplet-like shape and hangs down below the holding metal layer 93. As in this fourteenth modification, the insulating member 60 or the bottom wall 10a arranged below the fuse element 50 is provided with a storage through-hole 67 or a storage hole 68 as a storage recess 69, so that the molten material held by each holding metal layer 93 is disposed within the storage recess 69. The provision of the storage recess 69 allows the holding metal layer 93 to stably hold the molten material, and can prevent problems such as a short circuit from occurring due to, for example, unintended flow of the molten material.

[0196] The present invention is not limited to the above-described embodiment, and the configuration may be modified within the scope of the present invention, as described below. In the illustrations of other embodiments and modifications, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the following mainly describes the differences.

[0197] (Protection Element (Second Embodiment)) A protection element according to a second embodiment of the present invention will be described with reference to FIGS. 24 to 35. The protection element of the second embodiment differs from the first embodiment described above mainly in the arrangement of electrodes and the like on an insulating substrate 202 having a resistance layer 201. In each drawing of this embodiment, components that are the same or substantially the same as those in the first embodiment may be given the same reference numerals or names, and descriptions thereof may be omitted.

[0198] 24 is a top view showing an example of the heating element 80 of the second embodiment. In the example of FIG. 24, the protective element includes an insulating substrate 202 having a resistance layer 201, a soluble conductor 51 (not shown in FIG. 24) mounted on the insulating substrate 202, a first electrode 211 and a second electrode 212 connected to the resistance layer 201, a third electrode 213 arranged on the insulating substrate 202, a fifth electrode 215 connecting the first electrode 211 and the third electrode 213, and a first metal 221 formed on the third electrode 213 and the fifth electrode 215.

[0199] 25 is a top view showing another example of the heating element 80 of the second embodiment. In the example of FIG. 25, the protective element includes an insulating substrate 202 having a resistance layer 201, a soluble conductor 51 (not shown in FIG. 25) mounted on the insulating substrate 202, a first electrode 211 and a second electrode 212 connected to the resistance layer 201, a third electrode 213 and a fourth electrode 214 arranged on the insulating substrate 202, a fifth electrode 215 connecting the first electrode 211 and the third electrode 213, a sixth electrode 216 connecting the second electrode 212 and the fourth electrode 214, a first metal 221 formed on the third electrode 213 and the fifth electrode 215, and a second metal 222 formed on the fourth electrode 214 and the sixth electrode 216. The resistance layer 201 is covered with an insulating layer 203 from the upper side.

[0200] The resistive layer 201 is made of a conductive material that generates heat when a current is applied, such as nichrome, W, Mo, Ru, or a material containing any of these. The resistive layer 201 can be formed by mixing a powder of these alloys, compositions, or compounds with a resin binder or the like to form a paste, which is then patterned on the insulating substrate 202 using a screen printing technique and then fired. The material of the resistive layer 201 is not limited to the above and can be changed according to design specifications.

[0201] In the illustrated example, the resistive layer 201 extends in the left-right direction in a top view. In the illustrated example, the resistive layer 201 has a rectangular shape with a larger left-right dimension than a front-to-rear dimension. Specifically, the resistive layer 201 extends in a direction intersecting the current flow direction (generally the front-to-rear direction, partially including the up-and-down direction) in which current flows through the fuse element 50, and in the illustrated example, extends in a direction perpendicular to the current flow direction (i.e., the left-to-right direction). Note that the shape of the resistive layer 201 is not limited to the above and can be changed according to design specifications.

[0202] The insulating substrate 202 is an insulating substrate made of, for example, alumina, glass ceramics, mullite, zirconia, etc. The material of the insulating substrate 202 is not limited to the above and can be changed according to design specifications.

[0203] In the illustrated example, the insulating substrate 202 has a rectangular shape larger than the resistive layer 201 when viewed from above. Specifically, the insulating substrate 202 extends in a direction intersecting the current-carrying direction, and in the illustrated example, extends in a direction perpendicular to the current-carrying direction (left-right direction). Note that the shape of the insulating substrate 202 is not limited to the above and can be changed according to design specifications.

[0204] The insulating layer 203 is provided to protect the resistance layer 201. As the material of the insulating layer 203, for example, an insulating material such as ceramics or glass can be used. The insulating layer 203 can be formed by a method such as applying a paste of an insulating material and baking it. Note that the material of the insulating layer 203 is not limited to the above and can be changed according to the design specifications.

[0205] In the illustrated example, the insulating layer 203 has a rectangular shape in top view that is larger than the resistive layer 201 and smaller than the insulating substrate 202. Specifically, the insulating layer 203 extends in a direction intersecting the current-carrying direction, and in the illustrated example, extends in a direction perpendicular to the current-carrying direction (left-right direction). Note that the shape of the insulating layer 203 is not limited to the above and can be changed according to design specifications.

[0206] The first electrode 211 and the second electrode 212 have a portion extending in the front-rear direction at the left-right ends of the upper surface of the insulating substrate 202, and a portion extending in the left-right direction from the outer end of this portion to connect to the resistive layer 201. In the example shown in the figure, the first electrode 211 and the second electrode 212 have an L-shape facing in opposite directions to each other when viewed from above. A portion of the first electrode 211 and the second electrode 212 is exposed to the outside without being covered by the insulating layer 203. The shapes of the first electrode 211 and the second electrode 212 are not limited to those described above and can be changed according to design specifications.

[0207] The third electrode 213 and the fourth electrode 214 are arranged at the left and right ends of the upper surface of the insulating substrate 202, spaced apart in the front-to-rear direction from the first electrode 211 and the second electrode 212, respectively. In the example shown in the figure, the third electrode 213 and the fourth electrode 214 each have a rectangular shape when viewed from above. The third electrode 213 and the fourth electrode 214 are exposed to the outside without being covered by the insulating layer 203. The shapes of the third electrode 213 and the fourth electrode 214 are not limited to those described above and can be changed according to design specifications.

[0208] The fifth electrode 215 is disposed between the first electrode 211 and the third electrode 213 at one end in the left-right direction of the upper surface of the insulating substrate 202. In the example shown in the figure, the fifth electrode 215 has a rectangular shape when viewed from above. The fifth electrode 215 is exposed to the outside without being covered by the insulating layer 203. The shape of the fifth electrode 215 is not limited to the above and can be changed according to design specifications.

[0209] The fifth electrode 215 is, for example, a metal made of Ag (silver) or Cu (copper), or an alloy mainly composed of Ag or Cu. The fifth electrode 215 may contain Ag or Cu, and may be Ag alone, Cu alone, an Ag alloy, or a Cu alloy. An Ag alloy is an alloy with the highest Ag content among the metals contained in the alloy, and a Cu alloy is an alloy with the highest Cu content among the metals contained in the alloy. The material of the fifth electrode 215 is not limited to the above and can be changed according to the design specifications.

[0210] The sixth electrode 216 is disposed between the second electrode 212 and the fourth electrode 214 at the other left-right end of the upper surface of the insulating substrate 202 (the end opposite the fifth electrode 215 in the left-right direction). In the example shown in the figure, the sixth electrode 216 has a rectangular shape when viewed from above. The sixth electrode 216 is exposed to the outside without being covered by the insulating layer 203. The shape of the sixth electrode 216 is not limited to the above and can be changed according to design specifications.

[0211] The sixth electrode 216 is, for example, a metal made of Ag or Cu, or an alloy mainly composed of Ag or Cu. The sixth electrode 216 may be made of, for example, the same material as the fifth electrode 215. Note that the material of the sixth electrode 216 is not limited to the above and can be changed according to design specifications.

[0212] The first metal 221 is formed so as to straddle the upper surfaces of the third electrode 213 and the fifth electrode 215 in the front-to-rear direction. In the example shown in the figure, the first metal 221 has an oval shape that is long in the front-to-rear direction when viewed from above. The first metal 221 is exposed to the outside without being covered by the insulating layer 203. The shape of the first metal 221 is not limited to the above and can be changed according to design specifications.

[0213] The first metal 221 is, for example, Sn (tin) or an alloy containing Sn as its main component. The first metal 221 may contain Sn, and may be Sn alone or an Sn alloy. An Sn alloy is an alloy containing Sn as its main component. An Sn alloy is an alloy with the highest Sn content among all metals contained in alloys. Examples of Sn alloys include an Sn-Bi alloy, an In-Sn alloy, and an Sn-Ag-Cu alloy. Note that the material of the first metal 221 is not limited to the above and can be changed according to design specifications.

[0214] The second metal 222 is formed so as to straddle the upper surfaces of the fourth electrode 214 and the sixth electrode 216 in the front-to-rear direction. In the example shown in the figure, the second metal 222 has an oval shape that is long in the front-to-rear direction when viewed from above. The second metal 222 is exposed to the outside without being covered by the insulating layer 203. The shape of the second metal 222 is not limited to the above and can be changed according to design specifications.

[0215] The second metal 222 is, for example, Sn or an alloy containing Sn as a main component. The second metal 222 may be, for example, the same material as the first metal 221. Note that the material of the second metal 222 is not limited to the above and may be changed according to design specifications.

[0216] Fig. 26 is a side view of the insulating substrate 202 of the second embodiment, showing the state before the current-carrying member 90 is connected. Fig. 27 is a side view of the insulating substrate 202 of the second embodiment, showing the state after the current-carrying member 90 is connected but before current is passed through. Referring to Fig. 26 and Fig. 27 together, the thickness of the fifth electrode 215 is thinner than the thickness of the third electrode 213. In the example shown in the figure, the thickness of the electrode corresponds to the minimum length of the electrode in the up-down direction.

[0217] Although not shown, the thickness of the sixth electrode 216 is thinner than the thickness of the fourth electrode 214. For example, the thickness of the sixth electrode 216 may be approximately the same as the thickness of the fifth electrode 215. For example, the thickness of the fourth electrode 214 may be approximately the same as the thickness of the third electrode 213. Note that the relationship between the thicknesses of the electrodes is not limited to the above and can be changed according to design specifications.

[0218] A current-carrying member 90 for connecting to the resistance layer 201 is connected to the third electrode 213 and the fourth electrode 214. The current-carrying member 90 is, for example, a power supply line. Note that the current-carrying member 90 is not limited to an electric wire such as a power supply line, and may be a member that supplies power (power supply member). For example, the form of the current-carrying member 90 is not limited to the above and can be changed according to design specifications.

[0219] In the illustrated example, the third electrode 213 is connected to the current-carrying member 90 via a first metal 221 formed on the third electrode 213 and the fifth electrode 215. The first metal 221 functions, for example, as solder for connecting the third electrode 213 and the current-carrying member 90. In this embodiment, the fifth electrode 215, to which the current-carrying member 90 is not connected, is thinner than the third electrode 213, to which the current-carrying member 90 is connected.

[0220] Although not shown, the fourth electrode 214 is connected to the current-carrying member 90 via a second metal 222 formed on the fourth electrode 214 and the sixth electrode 216. The second metal 222 functions, for example, as solder for connecting the fourth electrode 214 and the current-carrying member 90. In this embodiment, the sixth electrode 216, to which the current-carrying member 90 is not connected, is thinner than the fourth electrode 214, to which the current-carrying member 90 is connected.

[0221] In this embodiment, the resistance layer 201 generates heat, blocking the soluble conductor 51, and the resistance value between the third electrode 213 and the fourth electrode 214 increases by more than 10 times due to the melting of the fifth electrode 215 caused by the melting of the first metal 221 and / or the melting of the sixth electrode 216 caused by the melting of the second metal 222.

[0222] As an example, we will explain below an example in which the resistance layer 201 generates heat, blocking the soluble conductor 51, and the resistance value between the third electrode 213 and the second electrode 212 increases by more than 10 times due to the melting of the fifth electrode 215 caused by the melting of the first metal 221.

[0223] FIG. 28 is a side view of the insulating substrate 202 of the second embodiment, showing a state in which a portion of the fuse element 50 has melted after current has been applied. FIG. 29 is a side view of the insulating substrate 202 of the second embodiment, showing a state in which a portion of the electrode of the heating element 80 has melted. FIG. 30 is a perspective view of the insulating substrate 202 of the second embodiment, showing a state before the current-carrying member 90 is connected (the insulating layer 203 is shown by a two-dot chain line). FIG. 31 is a perspective view of the insulating substrate 202 of the second embodiment, showing a state before the current-carrying member 90 is connected (the insulating layer 203 is shown by a solid line). FIG. 32 is a perspective view of the insulating substrate 202 of the second embodiment, showing a state after the current-carrying member 90 has been connected. FIG. 33 is a perspective view of the insulating substrate 202 of the second embodiment, showing a state in which a portion of the electrode of the heating element 80 has melted.

[0224] 28, when the resistance layer 201 generates heat, at least a portion of the soluble conductor 51 (an example of a portion of the fuse element 50) is melted, and the current to the fuse element 50 is cut off. In the example of FIG. 28, the soluble conductor 51 is melted (cut off), and more specifically, the soluble conductor 51 is melted by heating the resistance layer 201.

[0225] Thereafter, as the resistance layer 201 continues to generate heat, the entire insulating substrate 202 heats up. Because the insulating substrate 202 is a rectangular plate that is long in the left-right direction when viewed from above, the heat generated by the resistance layer 201 causes the left-right central side of the insulating substrate 202 to become hotter than the left-right outer edge sides. Furthermore, because heat escapes from the current-carrying member 90 at the left-right outer edge sides of the insulating substrate 202, the left-right outer edge sides of the insulating substrate 202 become cooler than the left-right center side. The insulating substrate 202 has a temperature distribution in which the left-right central side is hotter and the left-right outer edge sides are colder.

[0226] As shown in FIGS. 29 and 33, after the fusible conductor 51 is melted, the solder (first metal 221) of the current-carrying member 90 melts. Then, the fifth electrode 215, which is thinner than the third electrode 213, melts into the molten solder (first metal 221). The molten solder erodes the fifth electrode 215 and is attracted to the third electrode 213, which has higher wettability than the insulating substrate 202, due to surface tension. In this embodiment, the fifth electrode 215, which is thinner than the third electrode 213, functions as a cutoff portion that cuts off the current path of the heating element 80. Meanwhile, the third electrode 213, which is thicker than the fifth electrode 215, functions as a solder pool that attracts the molten solder (solder that has eroded the fifth electrode 215).

[0227] 29 and 33, the fifth electrode 215 is melted, and more specifically, the fifth electrode 215 is lost due to the phenomenon of being corroded by the molten solder (so-called solder erosion). Note that the fifth electrode 215 does not necessarily have to be lost completely between the first electrode 211 and the third electrode 213, and a molten residue may remain (a part of the fifth electrode 215 may remain).

[0228] The protective element of this embodiment may be configured, for example, so that the resistance value between the third electrode 213 and the second electrode 212 increases by 10 times or more when the fifth electrode 215 dissolves due to the melting of the first metal 221, thereby suppressing heat generation in the resistive layer 201. For example, the fifth electrode 215 may be configured so that even if it remains partially, its thickness decreases, thereby increasing its resistance value and preventing current from flowing in the current path of the heating element 80. For example, if the resistance value between the third electrode 213 and the second electrode 212 increases by 10 times or more, the amount of heat generated becomes 1 / 10 or less, thereby reducing the risk of destruction of the protective element due to overheating.

[0229] The protective element of the present embodiment described above includes an insulating substrate 202 having a resistance layer 201, a soluble conductor 51 mounted on the insulating substrate 202, a first electrode 211 and a second electrode 212 connected to the resistance layer 201, a third electrode 213 and a fourth electrode 214 arranged on the insulating substrate 202, a fifth electrode 215 connecting between the first electrode 211 and the third electrode 213, and a sixth electrode 216 connecting between the second electrode 212 and the fourth electrode 214, and a first metal 221 formed on the third electrode 213 and the fifth electrode 215, The fourth electrode 214 and the sixth electrode 216 are provided with a second metal 222 formed thereon, and the thickness of the fifth electrode 215 is thinner than that of the third electrode 213, and the thickness of the sixth electrode 216 is thinner than that of the fourth electrode 214. The resistance value between the third electrode 213 and the fourth electrode 214 is increased by 10 times or more due to the melting of the fifth electrode 215 caused by the melting of the first metal 221 and / or the melting of the sixth electrode 216 caused by the melting of the second metal 222. According to this configuration, after the meltable conductor 51 is melted by the heat generated by the resistive layer 201, the resistance value between the third electrode 213 and the fourth electrode 214 is increased by 10 times or more due to the melting of the fifth electrode 215 and / or the melting of the sixth electrode 216 caused by the melted solder, thereby reducing the amount of heat generated to 1 / 10 or less. Therefore, the risk of destruction due to overheating as a protective element can be reduced. In addition, in a structure in which the current path of the fuse element 50, through which a large current flows, is electrically isolated from the current path of the heating element 80, it is possible for the heating element 80 to automatically stop generating heat after the fuse element 50 melts.

[0230] In this embodiment, the first metal 221 is tin or an alloy containing tin as a main component, and the fifth electrode 215 is a metal made of silver or copper, or an alloy containing silver or copper as a main component. With this configuration, the fifth electrode 215 is more likely to dissolve in the molten first metal 221, which makes it easier for solder erosion to occur.

[0231] In this embodiment, the third electrode 213 and the fourth electrode 214 are connected to the current-carrying member 90 for the resistance layer 201. With this configuration, the thickness of the fifth electrode 215 and the sixth electrode 216, which are not connected to the current-carrying member 90, can be easily reduced, which makes it easier for solder erosion to occur.

[0232] Although not shown, for example, conventional heating elements in protective elements have the following problems (1) to (3). (1) While they can be easily manufactured for low-voltage specifications of several tens of volts, such as those for mobile devices, when it comes to specifications of several hundred volts and several hundred amperes intended for large-capacity batteries, it becomes difficult to ensure the heating element's withstand voltage and insulation after the fusible conductor is interrupted. (2) One heating element fusing method involves concentrating the molten material of the fuse element on a single third electrode disposed between the first and second electrodes, but this makes stable fusing difficult for large fuse elements intended for high currents. (3) In a structure in which the current path of the fuse element through which a large current flows and the current path of the heating element are electrically isolated, it becomes difficult to automatically shut off the heating element after the fuse element has blown. In contrast, according to the present embodiment, the above-described configuration can solve all of the above problems (1) to (3).

[0233] (Modification of Second Embodiment) Fig. 34 is a perspective view of an insulating substrate 202 according to a modification of the second embodiment, showing the state before the current-carrying member 90 is connected (the insulating layer 203 is shown by a two-dot chain line). Fig. 35 is a perspective view of an insulating substrate 202 according to a modification of the second embodiment, showing the state before the current-carrying member 90 is connected (the insulating layer 203 is shown by a solid line). In Figs. 34 and 35, components that are the same or substantially the same as those in the above-described embodiments may be denoted by the same reference numerals or names, and descriptions thereof may be omitted.

[0234] 25 , the sixth electrode 216 connecting the second electrode 212 and the fourth electrode 214 is provided at one location between the second electrode 212 and the fourth electrode 214, but this is not limiting. As shown in FIGS. 34 and 35 , for example, the sixth electrodes 216A and 216B may be provided at two locations on both sides of the fourth electrode 214A to which the current-carrying member 90 is connected. For example, the sixth electrodes 216A and 216B, which are thinner than the fourth electrode 214A, may be provided on both sides of the fourth electrode 214A. For example, the installation mode of the sixth electrodes 216A and 216B can be changed according to design specifications.

[0235] (Protective Element (Third Embodiment)) A protective element 300 according to a third embodiment of the present invention will be described with reference to FIGS. 36 to 40. The protective element 300 of the third embodiment differs from the first embodiment described above mainly in that a filler 301 is disposed in the internal pressure buffering space 16 formed inside the insulating case 10. Note that in the drawings of this embodiment, components that are the same or substantially the same as those in the first embodiment may be given the same reference numerals or names and descriptions thereof may be omitted.

[0236] 36 is a cross-sectional view showing an example of a filler 301 of the third embodiment. Referring to Fig. 36, the protective element 300 includes: a first terminal 91 and a second terminal 92 that are arranged apart from each other in a front-to-rear direction (an example of a first direction); a fuse element 50 that is arranged between the first terminal 91 and the second terminal 92 to electrically connect them and that melts when a current equal to or greater than a predetermined value flows; insulating members 60 that are arranged facing the fuse element 50 from both sides in a top-to-bottom direction (an example of a second direction orthogonal to the first direction); an insulating case 10 that accommodates a portion of the first terminal 91, a portion of the second terminal 92, the fuse element 50, and the insulating member 60, the insulating case 10 having an internal pressure buffering space 16 formed therein that communicates with a space 18 in which the fuse element 50 is arranged; and a filler 301 that is arranged in at least a portion of the internal pressure buffering space 16 and that contacts a surface of at least one of the insulating members 60 opposite to a surface that faces the fuse element 50.

[0237] The filler 301 has a function of filtering and cooling metal gas generated by arc discharge that occurs, for example, in a part of a circuit to be interrupted when an excessive current is flowing, thereby quickly and safely extinguishing the arc discharge. Note that the filler 301 is not limited to granular inorganic insulating material, and various materials can be used. For example, the form of the filler 301 can be changed according to the design specifications.

[0238] In the illustrated example, the filler 301 fills the internal pressure buffering space 16 inside the protective element 300. A portion of the filler 301 contacts the upper surface of the insulating member 60 located above the upper fuse element 50. For example, first, before the third holding member 10D (corresponding to the lid member that constitutes the insulating case 10) is mounted on the second holding member 10C, the filler 301 is placed in the internal pressure buffering space 16. Thereafter, the third holding member 10D is attached to the second holding member 10C, thereby filling the internal pressure buffering space 16 with the filler 301.

[0239] The filler 301 does not necessarily have to fill the internal pressure buffering space 16 completely without gaps, but may fill the internal pressure buffering space 16 with gaps in part. For example, the filler 301 may be disposed in at least a portion of the internal pressure buffering space 16 and contact the surface of at least one insulating member 60 opposite the surface facing the fuse element 50 (the upper surface in the illustrated example). For example, if the filler contacts and covers the surface of the fuse element, metal debris generated when the fuse element melts may continuously accumulate on the filler surface, forming a conductive path, which may lead to a risk of prolonged arc discharge and / or a decrease in insulation resistance after interruption. Therefore, it is preferable to dispose the filler 301 so as to avoid contact with the fuse element 50 as much as possible.

[0240] The orientation of the protective element 300 is not limited to being arranged so that its up-down direction (an example of a second direction perpendicular to the first direction) is aligned with the direction of gravity, but may also be arranged so that it intersects with the direction of gravity. For example, when the filler 301 is filled tightly into the internal pressure buffering space 16, even if the protective element 300 is arranged at an angle with respect to the direction of gravity, at least one insulating member 60 will be in contact with the surface opposite to the surface facing the fuse element 50. For example, the arrangement of the protective element 300 can be changed according to design specifications.

[0241] The filler 301 is, for example, silica sand. ２ Silica sand is a type of sand that is primarily composed of quartz grains. Specifically, silica sand is a white, coarse-grained sand that contains a large amount of quartz grains among sandy deposits and weathering products whose main components are silicates.

[0242] The filler 301 is not limited to silica sand, and various materials can be used. For example, the filler 301 may be a spherical member (e.g., ceramic beads or ceramic balls) made of a ceramic material such as quartz glass, alumina, or zirconia. For example, the filler 301 may be a porous member (e.g., porous ceramic) made of a ceramic material such as quartz glass, alumina, or zirconia. For example, the filler 301 may be a spherical member (e.g., plastic beads or plastic balls) made of a plastic material such as nylon or PMMA (acrylic resin). For example, the filler 301 may be a porous member (e.g., porous plastic) made of a plastic material such as nylon or PMMA.

[0243] The insulating member 60 may have a through hole 63 (e.g., a slit portion) formed therein, which passes through the insulating member 60 in the vertical direction. A portion of the filler 301 that has entered the through hole 63 may be in contact with a portion of the fuse element 50. Note that the filler 301 that has entered the through hole 63 does not have to be in contact with a portion of the fuse element 50. For example, the contact state between the filler 301 that has entered the through hole 63 and the fuse element 50 can be changed according to design specifications.

[0244] The protection element 300 further includes a heating element 80 arranged vertically overlapping the fuse element 50. The fuse element 50 may have a fusible conductor 51 stacked on the heating element 80 and a metal conductor 52 connecting the first terminal 91 or the second terminal 92 to the fusible conductor 51. The fusible conductor 51 may have a melting temperature lower than that of the metal conductor 52.

[0245] The protective element 300 further includes a power supply member 90 that supplies current to the heating element 80. The insulating case 10 accommodates a portion of the power supply member 90 and the heating element 80. The heating element 80 generates heat when current is passed through the power supply member 90, melting and blowing at least a portion of the fuse element 50.

[0246] The protective element 300 of the present embodiment described above includes a first terminal 91 and a second terminal 92 spaced apart from each other in a first direction, a fuse element 50 disposed between the first terminal 91 and the second terminal 92 to electrically connect them and melt when a current equal to or greater than a predetermined value flows therebetween, insulating members 60 disposed facing the fuse element 50 from both sides in a second direction perpendicular to the first direction, an insulating case 10 accommodating a portion of the first terminal 91, a portion of the second terminal 92, the fuse element 50, and the insulating member 60, the insulating case 10 having an internal pressure buffering space 16 formed therein that communicates with a space 18 in which the fuse element 50 is disposed, and a filler 301 disposed in at least a portion of the internal pressure buffering space 16 and in contact with a surface of at least one of the insulating members 60 opposite to a surface facing the fuse element 50. With this configuration, the fuse element 50 is sandwiched between the insulating members 60 from above and below. This minimizes the amount of air in the space (interrupting space) surrounding the melted portion of the fuse element 50, thereby suppressing the amount of air plasma that can serve as a path for arc discharge during overcurrent interruption. This suppresses the occurrence of large-scale arc discharge during melting of the fuse element 50. Additionally, the internal pressure buffering space 16 can suppress a sudden increase in the internal pressure of the protective element 300 due to gas generated by arc discharge during melting of the fuse element 50. This prevents damage to the insulating case 10. Furthermore, by disposing the filler 301 in at least a portion of the internal pressure buffering space 16 and having the insulating member 60 in contact with the surface opposite to the surface facing the fuse element 50, the insulating member 60 can suppress the occurrence of arc discharge, while the filler 301 can sufficiently suppress a sudden increase in the internal pressure of the protective element 300 due to molten debris entering the internal pressure buffering space 16. This suppresses the occurrence of large-scale arc discharge during melting of the fuse element 50, thereby providing a protective element 300 that can perform both overcurrent interruption and interruption functions in response to an interruption signal.

[0247] For example, sandwiching the fuse element 50 between insulating members 60 made of a highly tracking-resistant material such as nylon provides a spaced-apart interruption that suppresses arcing during high-voltage, large-current interruption. In addition, disposing filler 301 in the internal pressure buffering space 16 allows the filler 301 to absorb the arc energy, thereby suppressing arcing. As a result, an increase in internal pressure due to molten material in the fuse element 50 can be suppressed, and ejection of material and sparks to the outside of the insulating case 10 can be suppressed. This allows the current path to be interrupted more safely, even under high-voltage, large-current conditions.

[0248] For example, the filler 301 is granular SiO ２ By using silica sand (quartz glass), surface area can be ensured for each silica sand particle, making it easier to increase the surface area of ​​the filler 301 as a whole compared to when the filler 301 is plate-shaped. This makes it easier to prevent a sudden increase in the internal pressure of the protective element 300 due to molten debris entering the internal pressure buffering space 16. In addition, because quartz glass has a lower melting point than other ceramic materials, the endothermic reaction proceeds more quickly. This allows the heat from the molten debris entering the internal pressure buffering space 16 to be quickly absorbed, thereby preventing an increase in the internal pressure of the protective element 300. Furthermore, quartz glass is cheaper and more readily available than other ceramic materials, contributing to cost reduction.

[0249] 37 is a cross-sectional view showing an example of the arrangement of the filler in the third embodiment. In the example shown, fillers 311A ​​and 311B are arranged in the internal pressure buffering spaces 16 formed inside the upper and lower parts of the insulating case 10 of the protective element 310. In the example shown, the fillers 311A ​​and 311B fill the internal pressure buffering space 16 inside the protective element 310. A portion of the filler 311A ​​located in the upper internal pressure buffering space 16 contacts the upper surface of the insulating member 60 located above the upper fuse element 50. A portion of the filler 311B located in the lower internal pressure buffering space 16 contacts the lower surface of the insulating member 60 located below the lower fuse element 50.

[0250] According to this configuration, arc energy can be absorbed in the vertical direction by the filler 311A ​​arranged in the upper internal pressure buffering space 16 and the filler 311B arranged in the lower internal pressure buffering space 16. This configuration is particularly effective when the fuse element 50 has multiple layers.

[0251] 38 is a cross-sectional view showing another example of the filler of the third embodiment. In the example shown, the filler 321 fills the internal pressure buffer space 16 inside the protective element 320. A portion of the filler 321 contacts the upper surface of the insulating member 60 located above the upper fuse element 50.

[0252] The filler 321 is, for example, silicone. Silicone is an inorganic polymer with a main chain consisting of siloxane bonds in which silicon (Si) and oxygen (O) are repeatedly arranged. In the example shown in the figure, gel-like silicone is filled into the internal pressure buffer space 16.

[0253] According to this configuration, since the filler 321 is made of silicone, it is softer than when the filler 321 is plate-shaped, and therefore it is easier to absorb the molten debris and take it into the filler 321. Therefore, it is easier to prevent a sudden increase in the internal pressure of the protective element 320 due to the molten debris entering the internal pressure buffering space 16.

[0254] 39 is a cross-sectional view showing another example of the filler of the third embodiment. In the example shown, the filler 331 fills the internal pressure buffering space 16 inside the protective element 330. A portion of the filler 331 contacts the upper surface of the insulating member 60 located above the upper fuse element 50, via a portion of the insulating case 10 (the bottom of the internal pressure buffering space 16).

[0255] The filler 331 is a plate-shaped member (e.g., plate-shaped ceramic) made of a ceramic material such as quartz glass, alumina, zirconia, etc. In the example shown in the figure, a plurality of plate-shaped ceramics are stacked in the front-rear direction.

[0256] With this configuration, the filler 331 is a plate-shaped ceramic, and multiple plate-shaped ceramics are stacked in the front-to-rear direction, which increases the surface area that comes into contact with the arc. This makes it easier to prevent a sudden increase in the internal pressure of the protection element 330 due to molten debris entering the internal pressure buffering space 16.

[0257] 40 is a cross-sectional view showing another example of the filler of the third embodiment. In the example shown, the filler 341 fills the internal pressure buffering space 16 inside the protective element 340. A portion of the filler 341 contacts the upper surface of the insulating member 60 located above the upper fuse element 50, via a portion of the insulating case 10 (the bottom of the internal pressure buffering space 16).

[0258] The filler 341 is a plate-shaped member (e.g., plate-shaped ceramic) made of a ceramic material such as quartz glass, alumina, zirconia, etc. In the example shown in the figure, a plurality of plate-shaped ceramics are stacked in the vertical direction.

[0259] With this configuration, the filler 341 is a plate-shaped ceramic, and multiple plate-shaped ceramics are stacked vertically, thereby increasing the surface area that comes into contact with the arc. This makes it easier to prevent a sudden increase in the internal pressure of the protection element 340 due to molten debris entering the internal pressure buffering space 16.

[0260] (Protective Element (Fourth Embodiment)) A protective element 400 according to a fourth embodiment of the present invention will be described with reference to FIGS. 41 and 42. The protective element 400 of the fourth embodiment differs from the first embodiment described above mainly in that a filter 401 is disposed in the internal pressure buffering space 16 formed inside the insulating case 10. In the drawings of this embodiment, components that are the same or substantially the same as those in the first embodiment may be given the same reference numerals or names and descriptions thereof may be omitted.

[0261] 41 is a cross-sectional view showing an example of a filter 401 according to the fourth embodiment. Referring to Fig. 41 , the protective element 400 includes: a first terminal 91 and a second terminal 92 that are spaced apart in a front-to-rear direction (an example of a first direction); a fuse element 50 that is disposed between the first terminal 91 and the second terminal 92 to electrically connect them and that melts down when a current equal to or greater than a predetermined value flows; insulating members 60 that are disposed facing the fuse element 50 on both sides in a top-to-bottom direction (an example of a second direction orthogonal to the first direction); an insulating case 10 that accommodates a portion of the first terminal 91, a portion of the second terminal 92, the fuse element 50, and the insulating member 60, the insulating case 10 having an internal pressure buffering space 16 formed therein that communicates with a space in which the fuse element 50 is disposed; and a filter 401 that is disposed in at least a portion of the internal pressure buffering space 16 and in contact with a surface of at least one of the insulating members 60 opposite to a surface facing the fuse element 50.

[0262] The filter 401 has a function of suppressing an increase in internal pressure by, for example, collecting molten debris generated by arc discharge that occurs in a part of a circuit through which an excessive current is flowing that is to be interrupted. Note that the filter 401 is not limited to a material having the above function, and various materials can be used. For example, the configuration of the filter 401 can be changed according to design specifications.

[0263] In the illustrated example, the filter 401 is filled in the internal pressure buffering space 16. The filter 401 is not in close contact with the fuse element 50. A portion of the filter 401 is in contact with the upper surface of the insulating member 60 located above the upper fuse element 50. For example, first, the third holding member 10D (corresponding to the lid member that constitutes the insulating case 10) is removed from the second holding member 10C, and the filter 401 is then placed in the internal pressure buffering space 16. Thereafter, the third holding member 10D is attached to the second holding member 10C, allowing the filter 401 to be filled in the internal pressure buffering space 16.

[0264] The filter 401 does not necessarily have to be completely filled into the internal pressure buffering space 16 without any gaps, but may be filled with gaps in part of the internal pressure buffering space 16. For example, the filter 401 may be disposed in at least a part of the internal pressure buffering space 16, and at least one of the insulating members 60 may be in contact with the surface opposite to the surface facing the fuse element 50 (the upper surface in the illustrated example).

[0265] The orientation of the protective element 400 is not limited to being arranged so that its up-down direction (an example of a second direction perpendicular to the first direction) is aligned with the direction of gravity, but may also be arranged so that it intersects with the direction of gravity. For example, if the filter 401 is packed tightly into the internal pressure buffering space 16, even if the protective element 400 is arranged tilted with respect to the direction of gravity, at least one of the insulating members 60 will be in contact with the surface opposite to the surface facing the fuse element 50. For example, the arrangement of the protective element 400 can be changed according to design specifications.

[0266] The filter 401 is made of, for example, a fiber material. ２ MgO, CaO, TiO ２ , Al ２ O ３ , ZrO ２ Ceramic materials such as SiO ２ MgO, CaO, TiO ２ , Al ２ O ３ , ZrO ２ Artificial mineral fibers (MMMF) made of these materials are particularly preferred from the viewpoint of safety, including biosoluble fibers (biosoluble fiber: BSF, alkaline earth silicate: AES), alumina fibers (polycrystalline fiber: PCW), glass wool, rock wool, slag wool, and silica fibers. Alternatively, examples of fiber materials include plastic materials such as nylon and PMMA. The type of fiber material is not limited to the above and can be changed depending on the design specifications.

[0267] The filter 401 is not limited to being made of a fiber material and may be formed of a porous material. For example, the filter 401 may be formed of a sheet-like material. For example, the filter 401 may be ceramic fiber paper, biosoluble fiber paper, alumina fiber paper, glass wool paper, rock wool paper, slag wool paper, or silica fiber paper, and multiple ceramic fiber papers, biosoluble fiber papers, alumina fiber papers, glass wool papers, rock wool papers, slag wool papers, or silica fiber papers may be stacked and arranged in the internal pressure buffering space 16. For example, the filter 401 is not limited to being paper and may be in the shape of wool, a board, a block, or the like. For example, the form of the filter 401 can be changed according to design specifications.

[0268] The fuse element 50 may be a fusible conductor 51 having a lower melting point than the first terminal 91 and the second terminal 92. For example, the fusible conductor 51 may be a laminate including a low-melting-point metal layer and a high-melting-point metal layer. For example, the low-melting-point metal layer may be composed of Sn or a metal containing Sn as a main component. For example, the high-melting-point metal layer may be composed of Ag or Cu, or a metal containing Ag or Cu as a main component.

[0269] The protection element 400 further includes a heating element 80 arranged to be stacked on the fuse element 50 in the vertical direction. The fuse element 50 may have a fusible conductor 51 stacked on the heating element 80, and a metal conductor 52 connecting the first terminal 91 or the second terminal 92 to the fusible conductor 51. For example, the melting point of the metal conductor 52 may be higher than the melting point of the fuse element 50. In the fuse element 50, the fusible conductor 51 is stacked on the heating element 80.

[0270] The protective element 400 further includes a power supply member 90 that supplies current to the heating element 80. The insulating case 10 accommodates a portion of the power supply member 90 and the heating element 80. The heating element 80 generates heat when current is passed through the power supply member 90, melting and blowing at least a portion of the fuse element 50.

[0271] The protective element 400 of the present embodiment described above includes a first terminal 91 and a second terminal 92 spaced apart from each other in a first direction, a fuse element 50 disposed between the first terminal 91 and the second terminal 92 to electrically connect them and melt when a current equal to or greater than a predetermined value flows therethrough, insulating members 60 disposed facing the fuse element 50 from both sides in a second direction perpendicular to the first direction, an insulating case 10 accommodating a portion of the first terminal 91, a portion of the second terminal 92, the fuse element 50, and the insulating member 60, the insulating case 10 having an internal pressure buffering space 16 formed therein that communicates with a space 18 in which the fuse element 50 is disposed, and a filter 401 disposed in at least a portion of the internal pressure buffering space 16, the filter 401 having at least one insulating member 60 in contact with a surface opposite to a surface facing the fuse element 50. With this configuration, the fuse element 50 is sandwiched between the insulating members 60 from above and below. This minimizes the amount of air in the space (interrupting space) surrounding the melted portion of the fuse element 50, thereby suppressing the amount of air plasma that can serve as a path for arc discharge during overcurrent interruption. This suppresses the occurrence of large-scale arc discharge during melting of the fuse element 50. Additionally, the internal pressure buffering space 16 can suppress a sudden increase in the internal pressure of the protective element 400 due to gas generated by arc discharge during melting of the fuse element 50. This prevents damage to the insulating case 10. Furthermore, by disposing the filter 401 in at least a portion of the internal pressure buffering space 16 and having the insulating member 60 in contact with the surface opposite to the surface facing the fuse element 50, the insulating member 60 can suppress the occurrence of arc discharge, while the filter 401 can sufficiently suppress a sudden increase in the internal pressure of the protective element 400 due to molten debris entering the internal pressure buffering space 16. This suppresses the occurrence of large-scale arc discharge during melting of the fuse element 50, thereby providing a protective element 400 that can perform both overcurrent interruption and interruption functions in response to an interruption signal.

[0272] For example, sandwiching the fuse element 50 between insulating members 60 made of a highly tracking-resistant material such as nylon provides a spaced-apart interruption that suppresses arcing during high-voltage, high-current interruption. Furthermore, disposing a filter 401 in the internal pressure buffering space 16 allows the filter 401 to capture molten debris and suppress an increase in internal pressure, thereby suppressing arcing. As a result, an increase in internal pressure due to molten material in the fuse element 50 can be suppressed, and ejected debris and sparks can be prevented from being ejected outside the insulating case 10. This allows the current path to be interrupted more safely, even under high-voltage, high-current conditions.

[0273] For example, by making the filter 401 out of a fibrous material, the surface area of ​​the filter 401 can be secured, and compared to a plate-shaped ceramic, the surface area of ​​the entire filter 401 can be more easily increased. In addition, compared to a plate-shaped ceramic, the fibrous filter 401 has more elements to capture molten debris. Therefore, it is easier to suppress a sudden increase in the internal pressure of the protection element 400 due to molten debris entering the internal pressure buffering space 16.

[0274] 42 is a cross-sectional view showing an example of filter arrangement in the fourth embodiment. In the illustrated example, filters 411A and 411B are arranged in the internal pressure buffering spaces 16 formed inside the upper and lower parts of the insulating case 10 of the protective element 410. In the illustrated example, the filters 411A and 411B fill the internal pressure buffering space 16 inside the protective element 410. A portion of the filter 411A located in the upper internal pressure buffering space 16 contacts the upper surface of the insulating member 60 located above the upper fuse element 50. A portion of the filter 411B located in the lower internal pressure buffering space 16 contacts the lower surface of the insulating member 60 located below the lower fuse element 50.

[0275] With this configuration, molten debris can be captured in the vertical direction by the filter 411A arranged in the upper internal pressure buffering space 16 and the filter 411B arranged in the lower internal pressure buffering space 16. In addition, molten debris can be captured by the filters 411A and 411B on both sides in the vertical direction. This configuration is particularly effective when the fuse element 50 has multiple layers.

[0276] (Protective Element (Fifth Embodiment)) A protective element 500 according to a fifth embodiment of the present invention will be described with reference to FIGS. 43 to 45. The protective element 500 of the fifth embodiment differs from the first embodiment described above mainly in that the amount of carbon material contained in the insulating member 501 and / or the insulating case 502 is less than a predetermined amount. In the drawings of this embodiment, components that are the same or substantially the same as those in the first embodiment may be denoted by the same reference numerals or names, and descriptions thereof may be omitted.

[0277] 43 is a perspective view (cross-sectional perspective view) showing the appearance and cross section of a protection element 500 of a fifth embodiment. Referring to Fig. 43, the protection element 500 includes: a first terminal 91 and a second terminal 92 that are spaced apart from each other in a front-to-rear direction (an example of a first direction); a fuse element 50 that is disposed between the first terminal 91 and the second terminal 92 to electrically connect them and that melts when a current equal to or greater than a predetermined value flows; insulating members 501 that are disposed opposite the fuse element 50 from both sides in a top-to-bottom direction (an example of a second direction orthogonal to the first direction); and an insulating case 502 that accommodates a portion of the first terminal 91, a portion of the second terminal 92, the fuse element 50, and the insulating member 501, the insulating case 502 having an internal pressure buffering space 16 formed therein that communicates with a space 18 in which the fuse element 50 is disposed. The insulating member 501 and / or the insulating case 502 has a carbon material content of less than 0.1 wt%.

[0278] In the example shown in the figure, the insulating member 501 and the insulating case 502 each have a highly tracking-resistant insulating material sandwiching the fuse element 50, which is a resin material, and the carbon material content of the resin material is less than 0.1 wt %.

[0279] For example, a nylon material is preferable as an insulating material with high tracking resistance, and PA46 or PA66, which does not contain a benzene ring, is more preferable. Note that the insulating material is not limited to the above and can be changed according to the design specifications.

[0280] For example, the outer surface of the cover 10A (e.g., the pipe outside the insulating case 10) may be black (e.g., containing 0.5 wt % or more of carbon black) to enable laser marking on the insulating case 10. The color of the insulating case 10 is not limited to the above and can be changed according to design specifications.

[0281] For example, the carbon material is preferably amorphous (microcrystalline) carbon such as carbon black, activated carbon, carbon fiber, hard carbon, soft carbon, mesoporous carbon, etc. The carbon material is not limited to the above, and may be other solid carbon materials, and can be changed according to design specifications.

[0282] The insulating member 501 and / or insulating case 502 contain 10 wt % or more of glass fiber 503. It is more preferable that the insulating member 501 and / or insulating case 502 contain 30 wt % or more of glass fiber 503. In the example shown in the figure, the insulating member 501 and insulating case 502 each contain 30 wt % or more of glass fiber 503. For example, the glass fiber 503 may be SiO ２ MgO, Al ２ O ３ , ZrO ２ The glass fiber 503 is not limited to the above and can be changed according to the design specifications.

[0283] Fig. 44 is a side view of the insulating member 501 of the fifth embodiment, showing the state before interruption due to an overcurrent. Fig. 45 is a side view of the insulating member 501 of the fifth embodiment, showing the state in which a portion of the insulating member 501 has melted after interruption due to an overcurrent. Referring to Figs. 44 and 45 together, the insulating members 501 on both the upper and lower sides of the fuse element 50 are exposed to high-temperature arc discharge during an overcurrent interruption, causing portions of the insulating members 501 to melt and sublimate. As a result, some of the glass fibers 503 contained in the insulating member 501 become exposed, forming irregularities on the surface of the insulating member 501 facing the fuse element 50. These irregularities obstruct the conduction path, increasing the insulation resistance.

[0284] The protective element 500 of the present embodiment described above includes a first terminal 91 and a second terminal 92 that are arranged apart from each other in a first direction, a fuse element 50 that is arranged between the first terminal 91 and the second terminal 92 to electrically connect them and that melts when a current equal to or greater than a predetermined value flows, an insulating member 501 that is arranged facing the fuse element 50 on both sides in a second direction that is perpendicular to the first direction, and an insulating case 502 that houses a portion of the first terminal 91, a portion of the second terminal 92, the fuse element 50, and the insulating member 501, and in which an internal pressure buffering space 16 that communicates with the space 18 in which the fuse element 50 is arranged is formed inside the insulating case 502, and the insulating member 501 and / or the insulating case 502 have a carbon material content of less than 0.1 wt %. With this configuration, the surfaces of the insulating member 501 and the insulating case 502 are less likely to graphitize when exposed to arc discharge or molten debris from the high-temperature fuse element 50, compared to when the carbon material content of the insulating member 501 and the insulating case 502 is 0.1 wt % or more. This reduces the likelihood of new current paths being formed, improving arc suppression and post-interruption insulation resistance. In particular, if the insulating material of the insulating member 501 and the insulating case 502 is a material that does not contain a benzene ring, such as PA46 or PA66, there is no element that will graphitize, making it easier to improve insulation resistance. In addition, compared to when the carbon material content of the insulating member 501 and the insulating case 502 is 0.1 wt % or more, the appearance of the insulating member 501 and the insulating case 502 can be closer to a natural color.

[0285] In this embodiment, the insulating member 501 and / or insulating case 502 have a glass fiber 503 content of 10 wt % or more. With this configuration, the insulating member 501 and insulating case 502 are less likely to break than when the glass fiber 503 content of the insulating member 501 and insulating case 502 is less than 10 wt %. This makes it possible to safely interrupt the circuit. In addition, the strength of the insulating member 501 and insulating case 502 (corresponding to the housing of the protective element 500) can be improved, thereby improving durability against the impact of an arc explosion.

[0286] (Protection Element (Sixth Embodiment)) A protection element according to a sixth embodiment of the present invention will be described with reference to FIGS. 46 to 53. The protection element of the sixth embodiment differs from the first embodiment described above mainly in the configuration of the fuse element 600 that constitutes the protection element. In the drawings of this embodiment, components that are the same or substantially the same as those in the first embodiment may be given the same reference numerals or names and descriptions thereof may be omitted.

[0287] FIG. 46 is a top view showing a portion of a protection element (fuse element 600) of the sixth embodiment. FIG. 47 is a side view showing a portion of a protection element (fuse element 600) of the sixth embodiment. FIG. 48 is a top view showing an example of a portion of a protection element (fuse element 600) of the sixth embodiment. Referring to FIGS. 46 to 48 together, the fuse element 600 includes a first conductive material 601 and a second conductive material 602 formed of a material different from that of the first conductive material 601. The first conductive material 601 and the second conductive material 602 are connected in series to each other in the front-rear direction (corresponding to the current-carrying direction). The first conductive material 601 has a higher electrical resistance in the current-carrying direction than the second conductive material 602, and when viewed from the top-bottom direction (corresponding to the thickness direction perpendicular to the current-carrying direction), the first conductive material 601 has a lower electrical resistance than the second conductive material 602. An overlapping portion 605 is provided at a portion where the electrical material 601 and the second conductive material 602 are connected to each other, the first conductive material 601 has a shorter length in the left-right direction (corresponding to the width direction perpendicular to the current-carrying direction and the thickness direction) at the overlapping portion 605 than the second conductive material 602, and the second conductive material 602 has at least one corner 606 on the outer side in the width direction at the overlapping portion 605, and the at least one corner 606 forms an angle A of 100° or less when viewed from the thickness direction. Note that Fig. 46 also illustrates the heating element 80 arranged to overlap the fuse element 600 in the vertical direction, while Fig. 48 omits the overlapping portion 605.

[0288] In the illustrated example, two fuse elements 600 are stacked vertically (two-layer fuse elements 600), but this is not limiting. For example, only one fuse element 600 (single-layer fuse element 600) may also be used. For example, the stacking configuration of the fuse elements 600 can be changed according to design specifications.

[0289] The first conductive material 601 and the second conductive material 602 each have a plate-like shape. The fuse element 600 further includes a third conductive material 603. The fuse element 600 has the third conductive material 603, the first conductive material 601, and the second conductive material 602 connected in series in the direction of current flow in this order. In the example shown in the figure, the third conductive material 603 has the same plate shape as the second conductive material 602. The third conductive material 603 is made of the same material as the second conductive material 602.

[0290] For example, the first conductive material 601 is made of a material having a lower melting temperature than the second conductive material 602 and the third conductive material 603. In this embodiment, the first conductive material 601 has a higher electrical resistivity than the second conductive material 602 and the third conductive material 603. In this embodiment, the first conductive material 601 functions as a fusing portion of the fuse element 600 during both an overcurrent interruption and an active interruption.

[0291] The first conductive material 601 is plate-shaped, sheet-shaped, or foil-shaped and extends in a plane direction perpendicular to the vertical direction (X-Y plane direction). In the example shown in the figure, the first conductive material 601 has a rectangular plate shape whose left-right dimension is larger than its front-to-back dimension when viewed from the vertical direction. The first conductive material 601 is disposed, for example, in the center of the fuse element 600 in the front-to-back direction.

[0292] For example, the first conductive material 601 may be a laminate including a low-melting-point metal layer and a high-melting-point metal layer. Although not specifically shown, the first conductive material 601 may have a laminate including a low-melting-point metal layer including Sn (tin) and a high-melting-point metal layer including Ag (silver) or Cu (copper). This laminate has one or more low-melting-point metal layers and two or more high-melting-point metal layers, with the low-melting-point metal layers disposed between the high-melting-point metal layers. This laminate is formed, for example, by coating the periphery of the low-melting-point metal layer with a high-melting-point metal layer.

[0293] The low-melting-point metal layer of the laminate may contain Sn, and may be Sn alone or an Sn alloy. An Sn alloy is an alloy containing Sn as the main component. That is, the low-melting-point metal layer is composed of Sn or Sn as the main component. An Sn alloy is an alloy with the highest Sn content among metals contained in alloys. Examples of Sn alloys include an Sn-Bi alloy, an In-Sn alloy, and an Sn-Ag-Cu alloy.

[0294] The high-melting-point metal layer of the laminate may contain Ag or Cu, and may be Ag alone, Cu alone, an Ag alloy, or a Cu alloy. An Ag alloy is an alloy with the highest Ag content among the metals contained in the alloy, and a Cu alloy is an alloy with the highest Cu content among the metals contained in the alloy. That is, the high-melting-point metal layer is composed of Cu or Ag, or Cu or Ag as the main component.

[0295] The laminate may have a two-layer structure of a low-melting-point metal layer / a high-melting-point metal layer. Alternatively, it may have a multi-layer structure of three or more layers, including two or more high-melting-point metal layers, one or more low-melting-point metal layers, and the low-melting-point metal layers are arranged between the high-melting-point metal layers. Furthermore, the first conductive material 601 may be composed of a single layer of a low-melting-point metal layer containing Sn.

[0296] For example, the second conductive material 602 and the third conductive material 603 are made of Cu or Ag, or contain Cu or Ag as a main component.

[0297] The second conductive material 602 and the third conductive material 603 are plate-shaped, sheet-shaped, or foil-shaped. In the example shown in the figure, the second conductive material 602 and the third conductive material 603 are substantially rectangular plate-shaped, with the left-right dimension longer than the front-rear dimension when viewed from the top-bottom direction. A plurality of second conductive materials 602 and third conductive materials 603 are provided in the fuse element 600. The second conductive materials 602 and third conductive materials 603 are arranged, for example, at both ends of the fuse element 600 in the front-rear direction. In this embodiment, each fuse element 600 has a pair of second conductive materials 602 and third conductive materials 603.

[0298] The third conductive material 603, the first conductive material 601, and the second conductive material 602 are connected in series in this order to form a current path for the fuse element 600. The second conductive material 602 and the third conductive material 603 are connected in pairs to both ends of the first conductive material 601 in the current flow direction (corresponding to the front-to-rear direction) of the fuse element 600.

[0299] In the illustrated example, a first end of the first conductive material 601 is fixed below the front end of the second conductive material 602 (the +X end in the illustrated example). That is, the upper surface of the first end of the first conductive material 601 and the lower surface of the front end of the second conductive material 602 are connected to each other. In addition, a second end of the first conductive material 601 is fixed below the rear end of the third conductive material 603 (the -X end in the illustrated example). That is, the upper surface of the second end of the first conductive material 601 and the lower surface of the rear end of the third conductive material 603 are connected to each other. The first conductive material 601 is disposed below the pair of second and third conductive materials 602 and 603, and spans between them.

[0300] The overlapping portion 605 is a portion where the first conductive material 601 and the second conductive material 602 are connected to each other and overlap each other in a top view. The first conductive material 601 has a shorter widthwise length at the overlapping portion 605 than the second conductive material 602. In this embodiment, the ratio W2 / W1 of the widthwise length W1 of the first conductive material 601 at the overlapping portion 605 (hereinafter also referred to as the "width dimension W1 of the first conductive material 601") to the widthwise length W2 of the second conductive material 602 at the overlapping portion 605 (hereinafter also referred to as the "width dimension W2 of the second conductive material 602") is approximately 1.07.

[0301] For example, the ratio W2 / W1 is preferably greater than 1.0 and equal to or less than 32, more preferably equal to or greater than 1.06 and equal to or less than 8, and even more preferably equal to or greater than 1.06 and equal to or less than 4. For example, if the ratio W2 / W1 becomes too large, there is a risk that the fuse resistance value will become large and the rated current will not be able to be increased. Note that the ratio W2 / W1 is not limited to the above and can be changed according to the design specifications.

[0302] The second conductive material 602 has at least one corner 606 on the outer side in the width direction of the overlapping portion 605. In the example shown in the figure, the second conductive material 602 and the third conductive material 603 each have corners 606 (two corners 606) on both outer sides in the width direction of the overlapping portion 605. Note that the arrangement of the corners 606 in the second conductive material 602 and / or the third conductive material 603 is not limited to the above and can be changed according to design specifications.

[0303] The corner 606 has an angle A of 100° or less when viewed from the thickness direction. In the example shown in the figure, the angle A of the corner 606 is about 90° (substantially a right angle) when viewed from the thickness direction. Note that the angle A of the corner 606 is not limited to the above and can be changed according to the design specifications.

[0304] The fuse element 600 of the present embodiment described above comprises a first conductive material 601 and a second conductive material 602 formed from a material different from the first conductive material 601, the first conductive material 601 and the second conductive material 602 being connected in series to each other in the current-carrying direction, the first conductive material 601 having a higher electrical resistance in the current-carrying direction than the second conductive material 602, an overlapping portion 605 at a location where the first conductive material 601 and the second conductive material 602 are connected to each other when viewed in the thickness direction perpendicular to the current-carrying direction, the length of the first conductive material 601 in the width direction perpendicular to the current-carrying direction and the thickness direction at the overlapping portion 605 is shorter than that of the second conductive material 602, and the second conductive material 602 has at least one corner 606 on the outer side in the width direction at the overlapping portion 605, and the at least one corner 606 has an angle A of 100° or less when viewed in the thickness direction. As a result of extensive research, the inventors have found that the effectiveness of suppressing arc discharge during high-voltage, large-current interruption varies depending on the widthwise length of the overlapping portion 605 between the first conductive material 601 and the second conductive material 602 and / or the angle A of the outer corner 606 of the second conductive material 602 in the widthwise direction at the overlapping portion 605. According to this configuration, the widthwise length of the first conductive material 601 at the overlapping portion 605 is shorter than that of the second conductive material 602, and the outer corner 606 of the second conductive material 602 at the overlapping portion 605 has an angle A of 100° or less when viewed from the thickness direction. This more effectively suppresses arc discharge during high-voltage, large-current interruption than when the widthwise length of the first conductive material 601 at the overlapping portion 605 is the same as that of the second conductive material 602. This shortens the arc discharge duration during high-voltage, large-current interruption, thereby preventing large sparks from being ejected. Therefore, the current path can be interrupted more safely, even when interrupting high voltages and large currents.

[0305] As a result of extensive research, the inventors have found that the greater the ratio W2 / W1 of the widthwise length W1 of the overlapping portion 605 of the first conductive material 601 to the widthwise length W2 of the overlapping portion 605 of the second conductive material 602, the more likely arc discharge is suppressed. In this embodiment, by setting the ratio W2 / W1 to approximately 1.07, arc discharge that occurs when interrupting a high voltage or large current can be more effectively suppressed. In addition, excessive increase in fuse resistance can be suppressed, avoiding the risk of being unable to increase the rated current.

[0306] Fig. 49 is a top view showing another example of a portion (fuse element) of the protection element of the sixth embodiment. The overlapping portion is not shown in Fig. 49 . In the illustrated example, the widthwise length of the first conductive material 611 at the overlapping portion is extremely shorter than that of the second conductive material 612. The second conductive material 612 and the third conductive material 613 are connected in pairs to both ends of the first conductive material 611 in the current flow direction of the fuse element 610. In the illustrated example, the ratio W2 / W1 of the widthwise length W1 of the overlapping portion of the first conductive material 611 to the widthwise length W2 of the overlapping portion of the second conductive material 612 is approximately 6.

[0307] 50 is a top view showing another example of a portion (fuse element) of the protection element of the sixth embodiment. In the example shown, the second conductive material 622 and the third conductive material 623 each have chamfered corners 626 (two corners 626) on both outer sides in the width direction of the overlapping portion. The second conductive material 622 and the third conductive material 623 are connected as a pair to both ends of the first conductive material 621 in the current flow direction of the fuse element 620. In the example shown, the angle A of the corners 626 is approximately 100° (an example of an obtuse angle) when viewed from the thickness direction.

[0308] 51 is a top view showing another example of a portion (fuse element) of the protection element of the sixth embodiment. In the example shown, the second conductive material 632 and the third conductive material 633 each have rounded corners 636 (two rounded corners 636) on both outer sides in the width direction of the overlapping portion. The second conductive material 632 and the third conductive material 633 are connected in pair to both ends of the first conductive material 631 in the current flow direction of the fuse element 630. In the example shown, the rounded corners 636 are curved in an arc shape that convex outward when viewed in the thickness direction.

[0309] 52 is a top view showing another example of a portion (fuse element) of the protection element of the sixth embodiment. In the example shown, three (one example of a plurality) first conductive materials 641A, 641B, and 641C are arranged side by side in the width direction (corresponding to the left-right direction). In other words, the first conductive materials 641A, 641B, and 641C are configured by being divided in the width direction. The second conductive material 642 and the third conductive material 643 are connected in pairs to both ends of the first conductive materials 641A, 641B, and 641C in the current flow direction of the fuse element 640. Note that the division of the first conductive materials 641A, 641B, and 641C is not limited to the above and can be changed according to design specifications.

[0310] In the illustrated example, the width dimensions W1A, W1B, W1C of the first conductive materials 641A, 641B, 641C at the overlapping portion are shorter than the second conductive material 642. In the illustrated example, the total length of the width dimensions W1A, W1B, W1C of the first conductive materials 641A, 641B, 641C at the overlapping portion is shorter than the width dimension W2 of the second conductive material 642 at the overlapping portion.

[0311] 53 is a top view showing another example of a part (fuse element) of the protection element of the sixth embodiment. In the example shown in the figure, the terminal also serves as a low-resistance portion (corresponding to the second conductive material 652 and the third conductive material 653), and the terminal is connected to a high-resistance portion (corresponding to the first conductive material 651). The second conductive material 652 and the third conductive material 653 are connected in pair to both ends of the first conductive material 651 in the current-carrying direction of the fuse element 650.

[0312] The present invention may be combined with the various configurations described in the above-described embodiments and modifications, and may also include additions, omissions, substitutions, and other modifications of the configurations, without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the above-described embodiments, but is limited only by the claims.

[0313] The protective element according to the above embodiment of the present invention will be specifically described below by showing examples. Note that the following examples are specific examples to which the present invention is applied, and are not intended to limit the present invention.

[0314] Example A protective element of the example includes a first conductive material and a second conductive material formed of a material different from the first conductive material, the first conductive material and the second conductive material being connected in series in the current-carrying direction, the first conductive material having a higher electrical resistance in the current-carrying direction than the second conductive material, an overlapping portion at a location where the first conductive material and the second conductive material are connected to each other when viewed in the thickness direction perpendicular to the current-carrying direction, the length of the first conductive material in the width direction perpendicular to the current-carrying direction and the thickness direction at the overlapping portion being shorter than that of the second conductive material, and the second conductive material has corners on both outer sides in the width direction at the overlapping portion, the corners forming an angle of 90° when viewed in the thickness direction (corresponding to the configuration shown in FIG. 48 ).

[0315] Examples 1 and 2 were prepared. In Example 1, the widthwise length W1 of the overlapping portion of the first conductive material was 15 mm, the widthwise length W2 of the overlapping portion of the second conductive material was 16 mm, and the ratio W2 / W1 was 1.07. In Example 2, the widthwise length W1 of the overlapping portion of the first conductive material was 13 mm, the widthwise length W2 of the overlapping portion of the second conductive material was 16 mm, and the ratio W2 / W1 was 1.23.

[0316] Comparative Example (Comparative Example) Figure 54 is a top view showing a portion of a protective element (fuse element 600X) of a comparative example. Referring to Figure 54, the protective element of the comparative example has the same basic configuration as the protective element of the example, but differs in the widthwise length of the overlapping portion between the first conductive material 601X and the second conductive material 602X and the size of the angle A of the outer corner 606X in the widthwise direction between the second conductive material 602X and the third conductive material 603X at the overlapping portion. In the comparative example, the widthwise length of the first conductive material 601X at the overlapping portion is the same as that of the second conductive material 602X, and the angle A of the corner 606X is 135° when viewed from the thickness direction. In the comparative example, the widthwise length W1 of the first conductive material 601X at the overlapping portion is 13 mm, the widthwise length W2 of the second conductive material 602X at the overlapping portion is 13 mm, and the ratio W2 / W1 is 1.00.

[0317] (Evaluation Results) The current waveforms at the time of interruption of each protective element were measured by a high-voltage, large-current interruption test. The test conditions were a voltage of 400 V and a current of 2 kA. The evaluation results and the like are shown in Figs. 55 to 57. Fig. 55 is a diagram showing the results of a high-voltage, large-current interruption test of the protective element of the comparative example. Fig. 56 is a diagram showing the results of a high-voltage, large-current interruption test of the protective element of Example 1. Fig. 57 is a diagram showing the results of a high-voltage, large-current interruption test of the protective element of Example 2.

[0318] 55 to 57, it was confirmed that the protective element of the example had a shorter arc discharge time than the protective element of the comparative example. It was also confirmed that the arc terminated in approximately 30 ms in Example 1 (ratio W2 / W1 = 1.07), and in approximately 5 ms in Example 2 (ratio W2 / W1 = 1.23). This indicates that the larger the ratio W2 / W1, the more likely the arc discharge is to be suppressed.

[0319] Other embodiments will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for convenience in order to make the features easier to understand, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate changes can be made within the scope of the effects of the present invention.

[0320] Seventh Embodiment A protection element according to a seventh embodiment of the present invention will be described with reference to Figs. 58 to 62. The protection element according to this embodiment constitutes part of a high-voltage, high-current (100 V / 100 A or more) electric circuit that uses, for example, a lithium-ion secondary battery. The protection element is mounted on, for example, an electric vehicle (EV).

[0321] 58 to 62 , the protective element 700 includes a first fuse element 710 (an example of a fuse element), a first terminal 30 and a second terminal 40 connected to both ends of the first fuse element 710 in the current-carrying direction, and an insulating case 750 that houses a portion of the first terminal 30 and the second terminal 40 and the first fuse element 710. The first terminal 30 and the second terminal 40 are arranged spaced apart from each other in a predetermined direction. Each of the first terminal 30 and the second terminal 40 is plate-shaped.

[0322] The protective element 700 has an overcurrent interruption mechanism that cuts off the current path when an overcurrent (current greater than a predetermined value) that exceeds the rated current flows through the first fuse element 710, causing the first fuse element 710 to melt and cut off the current path.

[0323] Hereinafter, each configuration may be described using an XYZ Cartesian coordinate system (three-dimensional Cartesian coordinate system) in each figure. The predetermined direction in which the first terminal 30 and the second terminal 40 are aligned is referred to as the front-rear direction. The front-rear direction corresponds to the X-axis direction in each figure. Within the X-axis direction, the direction from the second terminal 40 to the first terminal 30 (-X side) is referred to as the front side, and the direction from the first terminal 30 to the second terminal 40 (+X side) is referred to as the rear side. Note that the front-rear direction is the direction connecting the first terminal 30 and the second terminal 40, and is also the direction in which electricity flows when the protection element 700 is in use, so it may also be referred to as the current flow direction.

[0324] The direction in which the plate surfaces of the first terminal 30 and the second terminal 40 face is referred to as the up-down direction. The up-down direction is a direction perpendicular to the front-rear direction and corresponds to the Z-axis direction in each drawing. In the up-down direction, the upper side corresponds to the +Z side, and the lower side corresponds to the -Z side.

[0325] The direction perpendicular to the front-rear direction and the up-down direction is called the left-right direction. The left-right direction corresponds to the Y-axis direction in each drawing. In the left-right direction, the left side corresponds to the -Y side, and the right side corresponds to the +Y side. Specifically, the -Y side is the left side when the protective element 700 is viewed from the rear (+X side), and the +Y side is the right side when the protective element 700 is viewed from the rear. The left-right direction may also be referred to as the width direction. In this case, for example, one side in the width direction corresponds to the -Y side, and the other side in the width direction corresponds to the +Y side.

[0326] In this embodiment, the terms "front side," "rear side," "upper side," "lower side," "left side," and "right side" are convenient names for clearly explaining the relative positional relationships of each component, and the actual positional relationships may be other than those indicated by these names.

[0327] (First Terminal, Second Terminal) Each of the first terminal 30 and the second terminal 40 has a plate shape that extends in a plane direction (XY plane direction) perpendicular to the up-down direction. In the example shown in the figure, each of the first terminal 30 and the second terminal 40 has a substantially rectangular plate shape. The first terminal 30 and the second terminal 40 are arranged apart from each other in the front-rear direction.

[0328] The rear end of the first terminal 30 is connected to the front end of the first fuse element 710. The front portion of the first terminal 30 protrudes forward from the insulating case 750 and is exposed to the outside of the insulating case 750. The front end of the second terminal 40 is connected to the rear end of the first fuse element 710. The rear portion of the second terminal 40 protrudes rearward from the insulating case 750 and is exposed to the outside of the insulating case 750.

[0329] The first terminal 30 comprises a terminal body 31 having an external terminal hole 32 formed therein, a conductor connecting portion 33 connected to the front end portion of the first fuse element 710, and a locking claw 34 engaged with the terminal locking portion 758 of the insulating case 750.

[0330] The terminal body 31 has a rectangular plate shape that is long in the front-rear direction. The rear portion of the terminal body 31 is disposed between the terminal mounting surface 757 and the terminal pressing surface 759 at the front of the insulating case 750, and is sandwiched between the terminal mounting surface 757 and the terminal pressing surface 759. The external terminal hole 32 is a circular hole that penetrates the terminal body 31 in the vertical direction. The conductor connecting portion 33 is disposed at the rear end of the first terminal 30 and extends in the left-right direction. For example, the front end of the first fuse element 710 is connected to the conductor connecting portion 33 by soldering or the like. The locking claw 34 protrudes in the left-right direction beyond the terminal body 31. Specifically, the locking claw 34 protrudes from both the left and right ends of the conductor connecting portion 33.

[0331] The second terminal 40 comprises a terminal body 41 having an external terminal hole 42 formed therein, a conductor connecting portion 43 connected to the rear end portion of the first fuse element 710, and a locking claw 44 that is locked to the terminal locking portion 758 of the insulating case 750.

[0332] The terminal body 41 has a rectangular plate shape that is long in the front-rear direction. The front portion of the terminal body 41 is disposed between the terminal mounting surface 757 and the terminal pressing surface 759 at the rear of the insulating case 750, and is sandwiched between the terminal mounting surface 757 and the terminal pressing surface 759. The external terminal hole 42 is a circular hole that penetrates the terminal body 41 in the vertical direction. The conductor connecting portion 43 is disposed at the front end of the second terminal 40 and extends in the left-right direction. For example, the rear end of the first fuse element 710 is connected to the conductor connecting portion 43 by soldering or the like. The locking claw 44 protrudes in the left-right direction beyond the terminal body 41. Specifically, the locking claw 44 protrudes from each of the left and right ends of the conductor connecting portion 43.

[0333] For example, one of the pair of external terminal holes 32, 42 is connected to the power supply side, and the other is connected to the load side. Note that this is not limited to the above, and the external terminal holes 32, 42 may be connected to a current path inside the load. For example, the connection mode of the external terminal holes 32, 42 can be changed according to design specifications.

[0334] For example, each of the first terminal 30 and the second terminal 40 is made of a metal such as copper, brass, or nickel. Brass is preferred as the material for the first terminal 30 and the second terminal 40 from the viewpoint of increasing rigidity, and copper is preferred from the viewpoint of reducing electrical resistance. When copper is used, it is preferred to subject the surface to an anti-rust treatment such as nickel plating, silver plating, or tin plating. The first terminal 30 and the second terminal 40 may be made of the same material or different materials. For example, the material of each of the first terminal 30 and the second terminal 40 can be changed according to design specifications.

[0335] (First Fuse Element) The first fuse element 710 is configured from a metal plate-shaped member, sheet-shaped member, metal foil, or the like. In the example shown in the figure, only one first fuse element 710 is provided, but this is not limited to this. For example, two first fuse elements 710 may be provided side by side in the vertical direction, or three or more first fuse elements 710 may be provided side by side. For example, the installation mode of the first fuse element 710 can be changed depending on the design specifications.

[0336] The first fuse element 710 has a first conductor 711, a first soluble conductor 712 (an example of a soluble conductor), and a second conductor 713 connected in series in the current-carrying direction. For example, the first soluble conductor 712 is made of a material having a lower melting temperature than each of the first conductor 711 and the second conductor 713. For example, the first soluble conductor 712 has a higher electrical resistivity than each of the first conductor 711 and the second conductor 713. The first soluble conductor 712 functions as a fusing portion of the first fuse element 710 when an overcurrent is interrupted.

[0337] The first fusible conductor 712 is plate-shaped, sheet-shaped, or foil-shaped and extends in a plane direction (XY plane direction) perpendicular to the vertical direction. In the example shown, the first fusible conductor 712 is a rectangular plate-shaped element whose horizontal dimension is larger than its front-to-back dimension when viewed from the vertical direction. The first fusible conductor 712 is disposed in the center of the first fuse element 710 in the front-to-back direction. In this embodiment, flux 75 is applied to at least one surface of the first fusible conductor 712.

[0338] For example, the first soluble conductor 712 is made of Sn (tin) or a metal mainly composed of Sn. Although not shown, the first soluble conductor 712 may be a laminate including a high-melting-point metal layer and a low-melting-point metal layer. This laminate may have one or more low-melting-point metal layers and two or more high-melting-point metal layers, with the low-melting-point metal layers arranged between the high-melting-point metal layers. This laminate may be formed, for example, by coating the periphery of the low-melting-point metal layer with a high-melting-point metal layer.

[0339] For example, the high-melting-point metal layer of the laminate is made of Ag (silver) or Cu (copper), or a metal mainly composed of Ag or Cu. The high-melting-point metal layer of the laminate may contain Ag or Cu, and may be Ag alone, Cu alone, an Ag alloy, or a Cu alloy. An Ag alloy is an alloy with the highest Ag content among the metals contained in the alloy, and a Cu alloy is an alloy with the highest Cu content among the metals contained in the alloy.

[0340] For example, the low-melting-point metal layer of the laminate is made of Sn or a metal containing Sn as a main component. The low-melting-point metal layer of the laminate only needs to contain Sn, and may be Sn alone or an Sn alloy. The Sn alloy is an alloy containing Sn as a main component. The Sn alloy has the highest Sn content among all metals contained in alloys. Examples of Sn alloys include Sn-Bi alloys, In-Sn alloys, and Sn-Ag-Cu alloys.

[0341] The laminate may have a two-layer structure of a low-melting-point metal layer / a high-melting-point metal layer. Alternatively, the laminate may have two or more high-melting-point metal layers, one or more low-melting-point metal layers, and a multilayer structure of three or more layers in which the low-melting-point metal layers are arranged between the high-melting-point metal layers. The first soluble conductor 712 may be composed of a single layer of a low-melting-point metal layer containing Sn.

[0342] Each of the first conductor 711 and the second conductor 713 is plate-shaped, sheet-shaped, or foil-shaped. In this embodiment, each of the first conductor 711 and the second conductor 713 is a metal plate-shaped member. In the example shown in the figure, each of the first conductor 711 and the second conductor 713 has a substantially rectangular plate shape in which the left-right dimension is shorter than the front-rear dimension when viewed from the top-bottom direction. In this embodiment, each of the first conductor 711 and the second conductor 713 is made of Ag or Cu, or a metal containing Ag or Cu as a main component. When copper is used, it is preferable to apply an anti-rust treatment such as nickel plating, silver plating, or tin plating to the surface.

[0343] The first conductor 711, the first fusible conductor 712, and the second conductor 713 are connected in series in this order to form a current path of the first fuse element 710. Each of the first conductor 711 and the second conductor 713 is connected to an end of the first fusible conductor 712 in the current direction in which current flows through the first fuse element 710 (approximately the front-to-back direction in the example shown in the figure).

[0344] The first conductor 711 is connected to one end of the first soluble conductor 712. In the example shown, the rear end of the first conductor 711 is fixed on the front end of the first soluble conductor 712. That is, the lower surface of the rear end of the first soluble conductor 711 is connected to the upper surface of the front end of the first soluble conductor 712. The second conductor 713 is connected to the other end of the first soluble conductor 712. In the example shown, the front end of the second conductor 713 is fixed on the rear end of the first soluble conductor 712. That is, the lower surface of the front end of the second conductor 713 is connected to the upper surface of the rear end of the first soluble conductor 712. The first soluble conductor 712 is arranged on the lower side of the first conductor 711 and the second conductor 713 and is bridged between them. In addition, the vertical relationship of the connection between the first soluble conductor 712 and the first conductor 711 and the second conductor 713 is not limited, and the first soluble conductor 712 may be arranged on the upper side of the first conductor 711 and the second conductor 713.

[0345] The first terminal 30 and the first conductor 711 are connected. In the illustrated example, the rear end of the first terminal 30 is fixed onto the front end of the first conductor 711. That is, the lower surface of the rear end of the first terminal 30 and the upper surface of the front end of the first conductor 711 are connected to each other. The second terminal 40 and the second conductor 713 are connected to each other. In the illustrated example, the front end of the second terminal 40 is fixed onto the rear end of the second conductor 713. That is, the lower surface of the front end of the second terminal 40 and the upper surface of the rear end of the second conductor 713 are connected to each other. Note that the vertical relationship of the connections between the first terminal 30 and the first conductor 711 and the vertical relationship of the connections between the second terminal 40 and the second conductor 713 are not limited. The upper surface of the rear end of the first terminal 30 and the lower surface of the front end of the first conductor 711 may be connected to each other, or the upper surface of the front end of the second terminal 40 and the lower surface of the rear end of the second conductor 713 may be connected to each other.

[0346] The first conductor 711 includes an inner plate portion 11A connected to the first fusible conductor 712 and a first buffer portion 715 that relieves physical stress.

[0347] The inner plate portion 11A has a plate shape extending in a plane direction (XY plane direction) perpendicular to the up-down direction. The rear end portion of the inner plate portion 11A is connected to the front end portion of the first fusible conductor 712 by soldering or the like.

[0348] The first buffer portion 715 is disposed between the front end of the inner plate portion 11A and the rear end of the first terminal 30. The first buffer portion 715 includes a first extension portion 15A extending downward from the front end of the inner plate portion 11A, a second extension portion 15B extending forward from the lower end of the first extension portion 15A, a third extension portion 15C extending upward from the front end of the second extension portion 15B, and a fourth extension portion 15D extending forward from the upper end of the third extension portion 15C. The upper surface of the fourth extension portion 15D is connected to the lower surface of the rear end (conductor connection portion 33) of the first terminal 30. For example, the fourth extension portion 15D is connected to the conductor connection portion 33 of the first terminal 30 by soldering or the like.

[0349] In the example shown in the figure, the first buffer portion 715 has a curved shape that protrudes downward. In other words, the first buffer portion 715 has a hat shape that protrudes downward when viewed from the left and right. Note that the first buffer portion 715 is not limited to the above, and may have a curved shape that protrudes upward. For example, the first buffer portion 715 may have a crank shape when viewed from the left and right. For example, the shape of the first buffer portion 715 can be changed according to design specifications.

[0350] The second conductor 713 includes an inner plate portion 13A connected to the first fusible conductor 712 and a second buffer portion 716 that relieves physical stress.

[0351] The inner plate portion 13A has a plate shape extending in a plane direction (XY plane direction) perpendicular to the up-down direction. The front end portion of the inner plate portion 13A is connected to the rear end portion of the first fusible conductor 712 by soldering or the like.

[0352] The second buffer portion 716 is disposed between the rear end of the inner plate portion 13A and the front end of the second terminal 40. The second buffer portion 716 includes a first extension portion 16A extending downward from the rear end of the inner plate portion 13A, a second extension portion 16B extending rearward from the lower end of the first extension portion 16A, a third extension portion 16C extending upward from the rear end of the second extension portion 16B, and a fourth extension portion 16D extending rearward from the upper end of the third extension portion 16C. The upper surface of the fourth extension portion 16D is connected to the lower surface of the rear end (conductor connection portion 43) of the second terminal 40. For example, the fourth extension portion 16D is connected to the conductor connection portion 43 of the second terminal 40 by soldering or the like.

[0353] In the illustrated example, the second buffer portion 716 has a curved shape that protrudes downward. In other words, the second buffer portion 716 has a hat shape that protrudes downward when viewed from the left and right. The second buffer portion 716 is not limited to the above, and may have a curved shape that protrudes upward. For example, the second buffer portion 716 may have a crank shape when viewed from the left and right. For example, the shape of the second buffer portion 716 can be changed according to design specifications.

[0354] (Insulating Case) The insulating case 750 has an overall columnar shape extending in the front-to-rear direction. The insulating case 750 is formed with a first buffer space 751 around the first buffer portion 715, a second buffer space 752 around the second buffer portion 716, an element accommodating space 753 in a portion of the first fuse element 710 other than the periphery of the first buffer portion 715 and other than the periphery of the second buffer portion 716, and an internal pressure buffering space 755 that communicates with the element accommodating space 753 via a leak hole 754 and / or a gap. The insulating case 750 is configured to be in close proximity to or in contact with a portion of the first fuse element 710 other than the periphery of the first buffer portion 715 and other than the periphery of the second buffer portion 716.

[0355] The insulating case 750 includes a first holding member 750A in which at least a first buffer space 751 is formed, a second holding member 750B in which an internal pressure buffer space 755 is formed, a third holding member 750C that shields an open surface 756 of the internal pressure buffer space 755, and a cover 750D that is inserted from a direction perpendicular to the stacking direction of the first holding member 750A, the second holding member 750B, and the third holding member 750C. Note that the first buffer space 751 may be formed in the second holding member 750B instead of the first holding member 750A.

[0356] The first holding member 750A is disposed at the lowest of the three holding members and is disposed below the first terminal 30, the second terminal 40, and the first fuse element 710. The first holding member 750A includes a terminal mounting surface 757, a terminal locking portion 758, and a conductor-facing recess 760.

[0357] The terminal mounting surface 757 is concave and recessed downward from the top surface of the first holding member 750A. The bottom surface of the terminal mounting surface 757 is flat and faces upward, and extends in a plane direction perpendicular to the up-down direction (XY plane direction). A pair of terminal mounting surfaces 757 are provided on the first holding member 750A. The pair of terminal mounting surfaces 757 are located at both ends of the first holding member 750A in the front-to-rear direction.

[0358] The terminal locking portions 758 are arranged on side walls that stand on the outer left-right portions of the first holding member 750A. The terminal locking portions 758 are groove-shaped extending in the vertical direction (in other words, concave and recessed outward in the left-right direction). The terminal locking portions 758 are wall surfaces that run along the top surface of the first holding member 750A and the openings of the side walls that face inward in the left-right direction. A pair of terminal locking portions 758 are arranged on each side (i.e., four in total) at both front-rear end portions of the first holding member 750A.

[0359] The conductor facing recess 760 is a recessed portion recessed downward from the central portion of the upper surface of the first holding member 750A in the front-to-rear direction of the first fuse element 710. The conductor facing recess 760 is a substantially rectangular hole opening upward. The bottom surface of the conductor facing recess 760 is flat and faces upward, extending in a plane direction (XY plane direction) perpendicular to the vertical direction. The bottom surface of the conductor facing recess 760 faces the lower surface of the first fusible conductor 712. The conductor facing recess 760 is arranged on the central side of the first holding member 750A in the front-to-rear direction. The front-to-rear dimension of the conductor facing recess 760 is larger than the front-to-rear dimension of the first fusible conductor 712. The conductor facing recess 760 may also be formed on the second holding member 750B side facing the first fuse element 710.

[0360] The second holding member 750B is located in the vertical center of the three holding members. The second holding member 750B is located above the first terminal 30, the second terminal 40, and the first fuse element 710. The upper surface of the second holding member 750B forms an open surface 756 of the internal pressure buffering space 755. The second holding member 750B has a terminal pressing surface 759.

[0361] The terminal pressing surface 759 is concave and recessed upward from the lower surface of the second holding member 750B. The bottom surface of the terminal pressing surface 759 is flat and faces downward, and extends in a plane direction perpendicular to the up-down direction (XY plane direction). A pair of terminal pressing surfaces 759 are provided on the second holding member 750B. The pair of terminal pressing surfaces 759 are arranged at both ends of the second holding member 750B in the front-to-rear direction. Note that the terminal pressing surface 759 may be formed on the side of the first holding member 750A facing the first terminals 30 and the second terminals 40.

[0362] The third holding member 750C is positioned at the top of the three holding members. The third holding member 750C has a shape that extends in a plane direction perpendicular to the up-down direction. The bottom surface of the third holding member 750C is flat and aligned with the top surface (open surface 756) of the second holding member 750B.

[0363] The cover 750D has a cylindrical shape that extends in the front-rear direction. In the example shown in the figure, the cover 750D has a cylindrical shape that opens in the front-rear direction. The three holding members 750A, 750B, and 750C are housed inside the cover 750D in a combined state lined up in the vertical direction. The cover 750D holds the three holding members 750A, 750B, and 750C in a fixed state by adhesive or the like.

[0364] When the first holding member 750A and the second holding member 750B are combined together, a first buffer space 751, a second buffer space 752, and an element accommodating space 753 are formed between the first holding member 750A and the second holding member 750B. The element accommodating space 753 accommodates the first fuse element 710.

[0365] A portion of the upper surface of the first holding member 750A (a portion of the surface facing the element accommodating space 753) is configured to be in close proximity to or in contact with the lower surface of a portion of the first fuse element 710 other than the periphery of the first buffer portion 715 and other than the periphery of the second buffer portion 716. A portion of the lower surface of the second holding member 750B (a portion of the surface facing the element accommodating space 753) is configured to be in close proximity to or in contact with the upper surface of a portion of the first fuse element 710 other than the periphery of the first buffer portion 715 and other than the periphery of the second buffer portion 716.

[0366] The first buffer space 751 and the second buffer space 752 are each formed between the inner wall surface of a recess recessed downward from the top surface of the first holding member 750A and the bottom surface of the second holding member 750B. Each of the first buffer space 751 and the second buffer space 752 has a rectangular parallelepiped shape that is elongated in the left-right direction when viewed from the top-bottom direction. The first buffer space 751 is formed in the front end portion of the first holding member 750A. The first buffer space 751 is located between the rear end of the front terminal mounting surface 757 of the first holding member 750A and a portion of the surface facing the front of the element accommodating space 753. The second buffer space 752 is formed in the rear end portion of the first holding member 750A. The second buffer space 752 is located between the front end of the rear terminal mounting surface 757 of the first holding member 750A and a portion of the surface facing the rear of the element accommodating space 753.

[0367] When the second holding member 750B and the third holding member 750C are combined, an internal pressure buffering space 755 is formed between the second holding member 750B and the third holding member 750C. The internal pressure buffering space 755 is a substantially rectangular parallelepiped space and communicates with the element accommodating space 753 via the leak hole 754 and / or a gap. For example, the vertical dimension of the internal pressure buffering space 755 is between one-third and one-half of the vertical dimension (external height) of the entire protective element 700. The internal pressure buffering space 755 acts to suppress a sudden increase in the internal pressure of the protective element 700 due to gas generated by arc discharge that occurs when the first fuse element 710 melts. The internal pressure buffering space 755 communicates with the element accommodating space 753 and allows gas generated when the first fuse element 710 interrupts an overcurrent to escape.

[0368] In the illustrated example, four leak holes 754 and / or gaps are spaced apart in the front-to-rear direction and one pair is spaced apart in the left-to-right direction. The leak holes 754 and / or gaps extend linearly in the up-down direction. For example, the opening area of ​​the leak holes 754 and / or gaps (the cross-sectional area of ​​the leak holes 754 and / or gaps when cut along a plane perpendicular to the up-down direction) is 20% or less of the length in the current-carrying direction of the area where the insulating case 750 and the first fuse element 710 are adjacent to or in contact with each other, but is not limited outside the area where the insulating case 750 and the first fuse element 710 are adjacent to or in contact with each other. The configuration of the leak holes 754 and / or gaps (number, location, shape, opening area, etc.) is not limited to the above and can be changed according to design specifications.

[0369] For example, the cover 750D and each of the holding members 750A, 750B, and 750C are preferably made of a material with a tracking resistance index (CTI) (resistance to tracking (carbonized conductive path) breakdown) of 500 V or more. The tracking resistance index (CTI) can be determined by a test based on IEC 60112.

[0370] The cover 750D and the holding members 750A, 750B, and 750C can be made of a resin material. Resin materials have a smaller heat capacity and a lower melting point than ceramic materials. Therefore, using a resin material for the holding members is preferable because it weakens arc discharge caused by gasification cooling (ablation) and, when molten and scattered metal particles adhere to the holding members, the surface of the holding members deforms or the adhesions aggregate, making the metal particles sparse and making it difficult to form a conduction path.

[0371] Examples of the resin material include polyamide-based resin and fluororesin. In this embodiment, the insulating case 750 is made of polyamide-based resin or fluororesin. The polyamide-based resin may be an aliphatic polyamide or a semi-aromatic polyamide. Examples of aliphatic polyamides include nylon 4, nylon 6, nylon 46, and nylon 66. Examples of semi-aromatic polyamides include nylon 6T, nylon 9T, and polyphthalamide (PPA) resin. An example of a fluororesin is polytetrafluoroethylene. Furthermore, polyamide-based resins and fluororesin are highly heat-resistant and flammable. In particular, aliphatic polyamides are less likely to produce graphite when burned. Therefore, forming the cover 750D and each retaining member using aliphatic polyamide more reliably prevents the formation of a new current path due to graphite produced by arc discharge when the first fuse element 710 melts.

[0372] (First Filler, Second Filler) The protective element 700 further includes a first filler 71 disposed in the first buffer space 751 to surround the first buffer section 715, and a second filler 72 disposed in the second buffer space 752 to surround the second buffer section 716. In this embodiment, each of the first filler 71 and the second filler 72 is made of an elastic resin. The elastic resin is a silicone resin or a photocurable acrylic resin.

[0373] The first filler 71 and the second filler 72 are not limited to the elastic resin described above, and may be silicone oil. For example, the first filler 71 and the second filler 72 are not limited to solids, and may be fluid, such as liquid or gel. For example, the first filler 71 and the second filler 72 may be any material that can remove gas from each buffer space while maintaining the buffering effect of each buffer section. For example, the first filler 71 and the second filler 72 may be the same or different. For example, the form of the first filler 71 and the second filler 72 may be changed according to design specifications.

[0374] In the illustrated example, the fillers 71 and 72 are respectively filled in the buffer spaces 751 and 752. For example, first, before the second holding member 750B is mounted on the first holding member 750A, the fillers 71 and 72 are respectively placed in the buffer spaces 751 and 752. Thereafter, the second holding member 750B is attached to the first holding member 750A, whereby the fillers 71 and 72 can be respectively filled in the buffer spaces 751 and 752.

[0375] The fillers 71 and 72 do not necessarily have to be completely filled into the buffer spaces 751 and 752, respectively, without leaving gaps, but may be filled with gaps in parts of the buffer spaces 751 and 752, respectively. For example, the fillers 71 and 72 may be disposed in at least parts of the buffer spaces 751 and 752, respectively, so as to surround at least the buffer portions 715 and 716.

[0376] (Third Filler) The protective element 700 further includes a third filler 73 disposed in at least a portion of the internal pressure buffering space 755. The third filler 73 has the function of filtering and cooling metal gas generated by arc discharge that occurs in a portion of a circuit through which an excessive current is flowing and that is to be interrupted, thereby quickly and safely extinguishing the arc discharge. In this embodiment, the third filler 73 includes at least insulating fiber or silica sand.

[0377] The insulating fiber is ceramic fiber paper. Although not shown, a plurality of ceramic fiber papers may be stacked and arranged in the internal pressure buffer space 755. The third filler 73 is not limited to the insulating fiber described above, and may be other fiber materials. For example, the fiber material may be SiO ２ MgO, Al ２ O ３ , ZrO ２ Examples of suitable fiber materials include ceramic materials such as nylon and PMMA, and plastic materials such as nylon and PMMA. The type of fiber material is not limited to the above and can be changed depending on the design specifications.

[0378] Silica sand is granular SiO ２Silica sand is a type of sand that is primarily composed of quartz grains. Specifically, silica sand is a white, coarse-grained sand that contains a large amount of quartz grains among sandy deposits and weathering products whose main components are silicates.

[0379] The third filler 73 is not limited to the above, and various other materials may be used. For example, the third filler 73 may be a spherical member (e.g., ceramic beads or ceramic balls) made of a ceramic material such as quartz glass, alumina, or zirconia. For example, the third filler 73 may be a porous member (e.g., porous ceramic) made of a ceramic material such as quartz glass, alumina, or zirconia. For example, the third filler 73 may be a spherical member (e.g., plastic beads or plastic balls) made of a plastic material such as nylon or PMMA (acrylic resin). For example, the third filler 73 may be a porous member (e.g., porous plastic) made of a plastic material such as nylon or PMMA. For example, the third filler 73 may be a sheet-like member, or may be in the shape of wool, a board, a block, or the like. For example, the third filler 73 may be a plate-like member (e.g., plate-like ceramic) made of a ceramic material such as quartz glass, alumina, or zirconia. For example, the third filler 73 may be silicone. Silicone is an inorganic polymer having a main chain of siloxane bonds in which silicon (Si) and oxygen (O) are repeatedly arranged. For example, the form of the third filler 73 can be changed according to design specifications.

[0380] In the illustrated example, the third filler 73 fills the internal pressure buffering space 755 inside the protective element 700. A portion of the third filler 73 contacts the bottom surface of the recess that forms the internal pressure buffering space 755 in the second holding member 750B located above the first fuse element 710. For example, first, before the third holding member 750C (corresponding to the lid member that constitutes the insulating case 750) is mounted on the second holding member 750B, the third filler 73 is placed in the internal pressure buffering space 755. Thereafter, the third holding member 750C is attached to the second holding member 750B, thereby filling the internal pressure buffering space 755 with the third filler 73.

[0381] The third filler 73 does not necessarily have to fill the internal pressure buffering space 755 completely without any gaps, but may fill the internal pressure buffering space 755 with gaps in part. For example, the third filler 73 may be disposed in at least a part of the internal pressure buffering space 755 and be in contact with the bottom surface of the recess that forms the internal pressure buffering space 755. The leak hole 754 and / or gaps that communicate between the element accommodating space 753 and the internal pressure buffering space 755 do not have to be filled with anything.

[0382] The orientation of the protective element 700 is not limited to being arranged so that its up-down direction is along the direction of gravity, and it may be arranged so that it intersects with the direction of gravity. For example, if the third filler 73 is filled without any gaps in the internal pressure buffering space 755, even if the protective element 700 is arranged at an angle with respect to the direction of gravity, it will be in contact with the bottom surface of the recess that forms the internal pressure buffering space 755. For example, the arrangement of the protective element 700 can be changed according to design specifications.

[0383] 58 and 59 , the protective element 700 includes a first fuse element 710, a first terminal 30 and a second terminal 40 connected to both ends of the first fuse element 710 in the current-carrying direction, and an insulating case 750 that accommodates portions of the first terminal 30 and the second terminal 40 and the first fuse element 710. An element accommodating space 753 is formed in the insulating case 750 so that a portion of the insulating case 750 is in close proximity to or in contact with at least a portion of the first fuse element 710. The element accommodating space 753 is formed in a portion sandwiched between a portion of the upper surface of a first holding member 750A and a portion of the lower surface of a second holding member 750B that constitute the insulating case 750.

[0384] The rated voltage of the protective element 700 is equal to or less than the value obtained by multiplying the inter-terminal distance D [mm] between the first terminal 30 and the second terminal 40 by the electric field strength of 30 [V / mm]. The rated voltage of the protective element 700 refers to the maximum voltage (applied voltage) that may be applied to the protective element 700. The inter-terminal distance D corresponds to the distance between the first terminal 30 and the second terminal 40 in the X direction (the distance between the terminal bodies 31, 41 in the X direction) (see FIGS. 58 and 59 ). The electric field strength is the value obtained by dividing the inter-terminal voltage by the inter-terminal distance D. The rated voltage of the protective element 700 may be controlled by a control device (not shown) based on the inter-terminal distance D [mm] between the first terminal 30 and the second terminal 40 and the electric field strength.

[0385] For example, the rated voltage of the protection element 700 may be equal to or greater than the value obtained by multiplying the inter-terminal distance D [mm] by the electric field strength of 15 [V / mm], or may be equal to or greater than the value obtained by multiplying the inter-terminal distance D [mm] by the electric field strength of 20 [V / mm]. Note that the lower limit of the rated voltage of the protection element 700 is not limited to the above and can be changed depending on the design specifications.

[0386] (Operation and Effect of the Present Embodiment) The protective element 700 of the present embodiment described above includes a first fuse element 710, a first terminal 30 and a second terminal 40 connected to both ends of the first fuse element 710 in the current-carrying direction, and an insulating case 750 that accommodates portions of the first terminal 30 and the second terminal 40 and the first fuse element 710. An element accommodating space 753 is formed in the insulating case 750 so that a portion of the insulating case 750 is in proximity to or in contact with at least a portion of the first fuse element 710. The rated voltage of the protective element 700 is equal to or less than a value obtained by multiplying the inter-terminal distance D [mm] between the first terminal 30 and the second terminal 40 by the electric field strength 30 [V / mm]. With this configuration, the rated voltage of the protective element 700 is equal to or less than the terminal distance D [mm] multiplied by the electric field strength of 30 V / mm. This more effectively suppresses arc discharges that occur during high-voltage, high-current interruptions compared to when the rated voltage of the protective element 700 exceeds the terminal distance D [mm] multiplied by the electric field strength of 30 V / mm. This configuration allows for higher voltages by appropriately setting the terminal distance D according to the rated voltage of the protective element 700 and controlling the electric field strength. Furthermore, this configuration narrows the space formed between a portion of the first fuse element 710 and the insulating case 750. This minimizes the amount of gas around the first fuse element 710, which is one of the sources of arc discharge that occurs during overcurrent interruptions. This suppresses plasma generated by ionization of gas, which is one of the sources of arc discharge, and thereby suppresses arc discharge. Additionally, there is no need to fill the area around the first fuse element 710 with silica sand, known as an arc-extinguishing agent, to suppress arc discharge. This prevents problems caused by continuous adhesion of molten debris to the surface of the arc-extinguishing agent (such as reduced interruption characteristics and reduced insulation resistance after interruption).This prevents arc discharge during interruption, makes it possible to interrupt high voltages and large currents, and prevents a decrease in insulation resistance after interruption.

[0387] In this embodiment, the first fuse element 710 has a first conductor 711 and a first fusible conductor 712 connected in series in the current-carrying direction. The first conductor 711 includes a first buffer portion 715 that relieves physical stress. The insulating case 750 includes a first buffer space 751 formed around the first buffer portion 715. The protective element 700 further includes a first filler 71 disposed in the first buffer space 751 to surround the first buffer portion 715. The insulating case 750 is configured to be in close proximity to or in contact with a portion of the first fuse element 710 other than the periphery of the first buffer portion 715. This configuration narrows the space formed between the insulating case 750 and a portion of the first fuse element 710 other than the periphery of the first buffer portion 715. In addition, the first buffer portion 715 of the first fuse element 710 is surrounded by the first filler 71. This minimizes the amount of gas around the first fuse element 710, which is one of the sources of arc discharge that occurs during overcurrent interruption. This suppresses the generation of plasma due to ionization of gas, which is one of the sources of arc discharge, thereby suppressing arc discharge. Additionally, there is no need to fill the area around the first fuse element 710 with silica sand, known as an arc-extinguishing agent, to suppress arc discharge. This eliminates problems (such as reduced interruption characteristics and reduced insulation resistance after interruption) caused by continuous adhesion of molten debris to the surface of the arc-extinguishing agent. This provides a protective element 700 that suppresses arc discharge during interruption, is capable of interrupting high voltages and large currents, and suppresses a decrease in insulation resistance after interruption. Furthermore, the first buffer portion 715 of the first fuse element 710 reduces physical stress, thereby reducing expansion / contraction and deformation due to the difference in thermal expansion between the first fuse element 710 and the insulating case 750. This ensures the reliability of the protective element 700 during temperature cycles. Therefore, it is possible to suppress arc discharge and alleviate the thermal expansion / contraction stress of the first fuse element 710 that accompanies the temperature cycle of the protection device 700 .

[0388] In this embodiment, the first fuse element 710 further includes a second conductor 713 connected in series with the first fusible conductor 712 in the direction of current flow. The first conductor 711 is connected to one end of the first fusible conductor 712. The second conductor 713 is connected to the other end of the first fusible conductor 712. The first terminal 30 is connected to the first conductor 711. The second terminal 40 is connected to the second conductor 713. The second conductor 713 includes a second buffer portion 716 that relieves physical stress. A second buffer space 752 is formed in the insulating case 750 around the second buffer portion 716. The protective element 700 further includes a second filler 72 arranged in the second buffer space 752 to surround the second buffer portion 716. With this configuration, the second buffer portion 716 of the first fuse element 710 is surrounded by the second filler 72, which makes it possible to minimize the amount of gas, which is one of the sources of arc discharge that occurs when an overcurrent is interrupted, around the first fuse element 710. This suppresses the generation of plasma due to ionization of the gas, which is one of the sources of arc discharge, and thereby suppresses arc discharge. In addition, physical stress is reduced in each of the first buffer portion 715 and the second buffer portion 716 of the first fuse element 710, which makes it possible to more effectively mitigate expansion / contraction and deformation due to the difference in thermal expansion between the first fuse element 710 and the insulating case 750.

[0389] In this embodiment, the insulating case 750 has an element accommodating space 753 formed in a portion other than the periphery of the first buffer portion 715 of the first fuse element 710, and an internal pressure buffering space 755 that communicates with the element accommodating space 753 via a leak hole 754 and / or a gap. The protective element 700 further includes a third filler 73 disposed in at least a portion of the internal pressure buffering space 755. The leak hole 754 and / or the gap that communicates between the element accommodating space 753 and the internal pressure buffering space 755 are not filled with anything. With this configuration, the insulating case 750 suppresses the occurrence of arc discharge, while the third filler 73 sufficiently suppresses a sudden increase in the internal pressure of the protective element 700 due to molten debris entering the internal pressure buffering space 755. Therefore, it is possible to suppress the occurrence of a large-scale arc discharge when the first fuse element 710 melts.

[0390] In this embodiment, each of the first conductor 711 and the second conductor 713 is a metal plate-shaped member. The insulating case 750 is configured to be in close proximity to or in contact with the front and back surfaces of the plate-shaped components other than the periphery of the first buffer portion 715 of the first conductor 711 and the periphery of the second buffer portion 716 of the second conductor 713. This configuration allows each of the first buffer portion 715 of the first conductor 711 and the second buffer portion 716 of the second conductor 713 to be formed by bending. For example, each of the first buffer portion 715 and the second buffer portion 716 can be easily formed by bending (pressing). In addition, arc discharge can be prevented from occurring in the front and back surfaces of the plate-shaped components other than the periphery of the first buffer portion 715 of the first conductor 711 and the periphery of the second buffer portion 716 of the second conductor 713.

[0391] In this embodiment, the first conductor 711 and the second conductor 713 are each made of Ag or Cu, or a metal primarily composed of Ag or Cu. This configuration tends to result in lower electrical resistivity compared to when the first conductor 711 and the second conductor 713 are each a laminate including a high-melting-point metal layer and a low-melting-point metal layer. Therefore, the first conductor 711 and the second conductor 713 made of a single layer including Ag or Cu can be thinner even when they have the same electrical resistance in the same area as a laminate including a high-melting-point metal layer and a low-melting-point metal layer. When the thicknesses of the first conductor 711 and the second conductor 713 are thin, the amount of molten material that flies off when the first fuse element 710 melts is proportionally smaller, resulting in higher insulation resistance after disconnection.

[0392] In this embodiment, the insulating case 750 includes a first holding member 750A having at least a first buffer space 751 formed therein, a second holding member 750B having an internal pressure buffer space 755 formed therein, a third holding member 750C that shields an open surface 756 of the internal pressure buffer space 755, and a cover 750D that is inserted from a direction perpendicular to the stacking direction of the first holding member 750A, the second holding member 750B, and the third holding member 750C. With this configuration, the first holding member 750A, the second holding member 750B, and the third holding member 750C are housed in a stacked state within the cover 750D, thereby maintaining these holding members fixed to one another. This stabilizes the posture of the first fuse element 710 and portions of the first and second terminals 30 and 40 that are disposed between the holding members.

[0393] In this embodiment, the first filler 71 and the second filler 72 are each made of an elastic resin. With this configuration, the first buffer portion 715 and the second buffer portion 716 of the first fuse element 710 are each surrounded by elastic resin, which makes it possible to more effectively mitigate expansion / contraction and deformation due to the difference in thermal expansion between the first fuse element 710 and the insulating case 750.

[0394] In this embodiment, the third filler 73 includes at least insulating fiber or silica sand. When the third filler 73 includes at least insulating fiber, the surface area of ​​the third filler 73 can be secured, making it easier to increase the overall surface area of ​​the third filler 73 compared to when it is plate-shaped. In addition, when the third filler 73 includes at least insulating fiber, there are more elements to capture molten debris compared to when it is plate-shaped. Therefore, it is easier to suppress a sudden increase in the internal pressure of the protective element 700 due to molten debris entering the internal pressure buffering space 755. When the third filler 73 includes at least silica sand, the surface area of ​​each silica sand particle can be secured, making it easier to increase the overall surface area of ​​the third filler 73 compared to when it is plate-shaped. Therefore, it is easier to suppress a sudden increase in the internal pressure of the protective element 700 due to molten debris entering the internal pressure buffering space 755.

[0395] In this embodiment, flux 75 is applied to at least one surface of the first soluble conductor 712. According to this configuration, when an overcurrent flows, the first soluble conductor 712 is easily melted, and the overcurrent interruption speed can be improved.

[0396] In this embodiment, the insulating case 750 is made of a polyamide-based resin or a fluororesin. With this configuration, polyamide-based resins and fluororesin have high heat resistance and are resistant to combustion. In particular, aliphatic polyamides are less likely to produce graphite even when burned. Therefore, by forming the insulating case 750 from aliphatic polyamide, graphite production due to arc discharge when the first fuse element 710 melts can be suppressed, and the formation of a new current path can be more reliably prevented.

[0397] In this embodiment, the first fuse element 710 includes the first fusible conductor 712 and the conductor, which are made of different materials. However, this is not limited to this. For example, the entire first fuse element 710 may be composed of Ag or Cu, or Ag or Cu as the main component. In this case, the first fuse element 710 includes Ag or Cu. The first fuse element 710 may be Cu alone, Ag alone, a Cu alloy, or an Ag alloy.

[0398] The present invention is not limited to the above-described embodiment, and the configuration may be modified within the scope of the present invention, as described below. In the illustrations of other embodiments and modifications, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the following mainly describes the differences.

[0399] Eighth Embodiment A protective element 800 according to an eighth embodiment of the present invention will be described with reference to Figs. 63 to 66. The protective element 800 of the second embodiment differs from the seventh embodiment described above mainly in that it includes a heating element 80 and a power supply member 881. In the drawings of this embodiment, components that are the same or substantially the same as those in the seventh embodiment may be denoted by the same reference numerals or names, and descriptions thereof may be omitted.

[0400] 63 to 66, the protective element 800 includes a first fuse element 710, a first terminal 30 and a second terminal 40 connected to both ends of the first fuse element 710 in the current-carrying direction, a heating element 80, a power supply member 881 connected to the heating element 80, and an insulating case 850 that houses a portion of the first terminal 30 and the second terminal 40, the first fuse element 710, the heating element 80, and a portion of the power supply member 881.

[0401] The protective element 800 of this embodiment has a mechanism for interrupting the current path, which includes an overcurrent interruption mechanism in which the first fuse element 710 melts and interrupts the current path when an overcurrent (current equal to or greater than a predetermined value) exceeding the rated current flows through the first fuse element 710, and an active interruption mechanism in which, when an abnormality other than an overcurrent occurs, a current is passed through the heating element 80, causing it to generate heat, thereby melting the first fuse element 710 and interrupting the current path.

[0402] The heating element 80 is arranged so as to overlap the first fuse element 710 in the vertical direction. The heating element 80 is in contact with the first fuse element 710 in the vertical direction. The heating element 80 generates heat when current is passed through the power supply member 881, melting and blowing at least a portion of the first fuse element 710. Specifically, the heating element 80 is arranged so as to overlap the first fusible conductor 712 in the vertical direction, and is stacked in the vertical direction with the rear end of the first conductor 711 and the front end of the second conductor 713. The heating element 80 melts and blows at least a portion of the first fusible conductor 712 due to the heat generated by the current. In the following description, "melt and blow at least a portion" may be abbreviated to "melt and blow."

[0403] In the illustrated example, the heating element 80 is plate-shaped, with a pair of plate surfaces facing the vertical direction. When viewed from the vertical direction, the heating element 80 has a rectangular plate shape with a larger left-right dimension than a front-to-back dimension. The heating element 80 is placed in a heating element housing portion 61 formed in the insulating case 850. In other words, the heating element 80 is housed in the insulating case 850.

[0404] The heating element accommodating portion 61 is recessed from the surface of the insulating case 850 facing the first fuse element 710 of the second holding member 750B. In the example shown in the figure, the heating element accommodating portion 61 is recessed upward from the lower surface of the second holding member 750B. The heating element accommodating portion 61 is disposed toward the center of the second holding member 750B in the front-to-rear direction. The heating element accommodating portion 61 is a rectangular hole that is long in the left-to-right direction. In the example shown in the figure, the front-to-rear dimension of the conductor-facing recess 760 is smaller than the front-to-rear dimension of the heating element accommodating portion 61. The vertical dimension (depth dimension) of the conductor-facing recess 760 is smaller than the vertical dimension of the heating element accommodating portion 61.

[0405] Heating element 80 extends in a direction intersecting the current flow direction (approximately corresponding to the front-to-rear direction) in which current flows through first fuse element 710, and in the example shown in the figure, extends in a direction perpendicular to the current flow direction (i.e., the left-to-right direction). Although not shown, heating element 80 has an insulating substrate (substrate), a resistive layer laminated on the insulating substrate, a metal layer laminated on the insulating substrate and facing the first fuse element 710 in the top-to-bottom direction, an insulating layer, and a heating element electrode.

[0406] For example, when an abnormality occurs in the external circuit that serves as the current path for the protective element 800 and it becomes necessary to cut off the current path, the heating element 80 is energized and generates heat by a current control element provided in the external circuit.

[0407] The power supply member 881 is a member that supplies power to the heating element 80. The power supply member 881 extends from the outside to the inside of the insulating case 850, and one end thereof is connected to a heating element electrode (not shown) of the heating element 80. For example, at least a portion of the power supply member 881 is made of an electric wire (wiring member). Note that at least a portion of the power supply member 881 is not limited to the above, and may be made of a conductive plate-shaped member or rod-shaped member, etc., although not particularly shown.

[0408] The insulating case 850 includes a first holding member 750A in which at least a first buffer space 751 is formed, a second holding member 750B in which an internal pressure buffer space 755 is formed, a third holding member 750C that shields an open surface 756 of the internal pressure buffer space 755, and a first cover 850D1 and a second cover 850D2 that are inserted from both directions perpendicular to the stacking direction of the first holding member 750A, the second holding member 750B, and the third holding member 750C. Note that the first buffer space 751 may be formed in the second holding member 750B instead of the first holding member 750A.

[0409] Each of the first cover 850D1 and the second cover 850D2 has a cylindrical shape extending in the front-rear direction. In the illustrated example, each of the first cover 850D1 and the second cover 850D2 has a cylindrical shape that opens in the front-rear direction. The first cover 850D1 and the second cover 850D2 have approximately the same front-rear length. The three holding members are housed within the first cover 850D1 and the second cover 850D2 in a combined state aligned vertically. The first cover 850D1 and the second cover 850D2 hold the three holding members 750A, 750B, and 750C in a fixed state by adhesive or the like. The power supply member 881 extends in the left-right direction through the gap between the first cover 850D1 and the second cover 850D2. Note that the first cover 850D1 and the second cover 850D2 may have different front-rear lengths.

[0410] In this embodiment, the leak hole and / or gap 854 is formed at a position different from the leak hole 754 and / or gap described above. In the illustrated example, two leak holes and / or gaps 854 are arranged at an interval in the front-to-rear direction. The leak holes and / or gaps 854 extend linearly in the up-down direction. The leak holes and / or gaps 854 extend linearly in the left-to-right direction. The leak holes and / or gaps 854 are arranged near the heating element 80. The leak holes and / or gaps 854 are arranged along the front and rear edges of the heating element 80 when viewed from the up-down direction. The left-to-right dimension of the leak holes and / or gaps 854 is larger than the left-to-right dimension of the heating element 80. For example, the opening area of ​​the leak hole 754 and / or gap 854 (the sum of the cross-sectional areas of the leak hole 754 and / or gap 854 when cut by a plane perpendicular to the up-down direction) is 20% or less of the length in the current-carrying direction of the area where the first fuse element 710 and the insulating case 10 are close to or in contact with each other in the area where the insulating case 750 and the first fuse element 710 are close to or in contact with each other, but is not limited outside the area where the insulating case 750 and the first fuse element 710 are close to or in contact with each other. For example, the left-right dimension of the leak hole and / or gap 854 may be equal to or less than the left-right dimension of the heating element 80. For example, the leak hole 754 and / or gap 854 may be formed without being formed. For example, the leak hole and / or gap 854 may be formed instead of the leak hole 754 and / or gap, or the leak hole and / or gap 854 may be formed together with the leak hole 754 and / or gap. The configuration of the leak holes 754 and / or gaps 854 (number, location, shape, opening area, etc.) is not limited to the above and can be changed according to design specifications.

[0411] 63 and 64 , in this embodiment as well, an element accommodating space 753 is formed in the insulating case 850 so that a portion of the insulating case 850 is in close proximity to or in contact with at least a portion of the first fuse element 710. The rated voltage of the protective element 800 is equal to or less than the value obtained by multiplying the inter-terminal distance D [mm] between the first terminal 30 and the second terminal 40 by the electric field strength 30 [V / mm].

[0412] The protective element 800 of the present embodiment described above can more effectively suppress arc discharge that occurs during high-voltage, large-current interruption compared to when the rated voltage of the protective element 800 exceeds the terminal distance D [mm] multiplied by the electric field strength of 30 [V / mm]. Furthermore, because the space formed between a portion of the first fuse element 710 and the insulating case 850 is narrowed, gas, which is one of the sources of arc discharge that occurs during overcurrent interruption, can be eliminated as much as possible around the first fuse element 710. Therefore, arc discharge during interruption is suppressed, high-voltage, large-current interruption is possible, and a decrease in insulation resistance after interruption can be suppressed.

[0413] In the protective element 800 of this embodiment, when an overcurrent exceeding the rated current (i.e., a current equal to or greater than a predetermined value) flows through the first fuse element 710, the first fuse element 710 generates heat and melts, thereby interrupting the current path. Furthermore, the protective element 800 can interrupt the current path by passing a current through the heating element 80 to generate heat, thereby melting and melting the first fuse element 710 stacked on the heating element 80. According to this embodiment, it is possible to prevent a large-scale arc discharge from occurring when the first fuse element 710 melts, and it is possible to provide a protective element 800 that can perform both an overcurrent interruption and an interruption function in response to an interruption signal.

[0414] Ninth Embodiment A protection element 900 according to a ninth embodiment of the present invention will be described with reference to Figures 67 and 68. The protection element 900 of the ninth embodiment differs from the seventh embodiment described above mainly in that it further includes a second fuse element 920 arranged in parallel with the first fuse element 710, and an insulating member 990. In the drawings of this embodiment, components that are the same or substantially the same as those in the seventh embodiment may be denoted by the same reference numerals or names, and descriptions thereof may be omitted.

[0415] 67 and 68, the protective element 900 includes a second fuse element 920 arranged in parallel with the first fuse element 710 and connected to the first terminal 30 and the second terminal 40, an insulating member 990 arranged between the first fuse element 710 and the second fuse element 920, and an insulating case 950 that houses a portion of the first terminal 30 and the second terminal 40, the first fuse element 710, the second fuse element 920, and the insulating member 990.

[0416] The second fuse element 920 is configured from a metal plate-shaped member, sheet-shaped member, metal foil, or the like. In the example shown in the figure, only one second fuse element 920 is provided, but this is not limited to this. For example, two second fuse elements 920 may be provided side by side in the vertical direction, or three or more second fuse elements 920 may be provided side by side. For example, the installation mode of the second fuse element 920 can be changed depending on the design specifications.

[0417] The second fuse element 920 has a third conductor 921, a second fusible conductor 922, and a fourth conductor 923 connected in series in the current flow direction (specifically, the current flow direction of the second fuse element 920). For example, the second fusible conductor 922 is made of a material with a lower melting temperature than each of the third conductor 921 and the fourth conductor 923. For example, the second fusible conductor 922 has a higher electrical resistivity than each of the third conductor 921 and the fourth conductor 923. The second fusible conductor 922 functions as a fusing portion of the second fuse element 920 when an overcurrent is interrupted.

[0418] The second fusible conductor 922 is plate-shaped, sheet-shaped, or foil-shaped and extends in a plane direction (XY plane direction) perpendicular to the vertical direction. In the example shown, the second fusible conductor 922 is a rectangular plate-shaped element whose horizontal dimension is larger than its front-to-back dimension when viewed from the vertical direction. The second fusible conductor 922 is disposed in the center of the second fuse element 920 in the front-to-back direction. In this embodiment, flux 75 is applied to at least one surface of the second fusible conductor 922.

[0419] For example, the second soluble conductor 922 is made of Sn (tin) or a metal mainly composed of Sn. Although not shown, the second soluble conductor 922 may be a laminate including a high-melting-point metal layer and a low-melting-point metal layer. For example, the second soluble conductor 922 is formed of the same material as the first soluble conductor 712. Note that the second soluble conductor 922 is not limited to the above and may be formed of a material different from the first soluble conductor 712. For example, the material of the second soluble conductor 922 can be changed according to the design specifications.

[0420] The third conductor 921 and the fourth conductor 923 are each plate-shaped, sheet-shaped, or foil-shaped. In this embodiment, the third conductor 921 and the fourth conductor 923 are each a metal plate-shaped member. In the example shown in the figure, the third conductor 921 and the fourth conductor 923 are each a substantially rectangular plate-shaped member whose left-right dimension is shorter than its front-rear dimension when viewed from the top-bottom direction. In this embodiment, the third conductor 921 and the fourth conductor 923 are each made of Ag or Cu, or a metal containing Ag or Cu as a main component.

[0421] The third conductor 921, the second fusible conductor 922, and the fourth conductor 923 are connected in series in this order to form a current path of the second fuse element 920. Each of the third conductor 921 and the fourth conductor 923 is connected to an end of the second fusible conductor 922 in the current direction in which current flows through the second fuse element 920 (approximately the front-to-back direction in the example shown in the figure).

[0422] The third conductor 921 is connected to one end of the second soluble conductor 922. In the example shown, the rear end of the third conductor 921 is fixed to the front end of the second soluble conductor 922. Specifically, the upper surface of the rear end of the third conductor 921 is connected to the lower surface of the front end of the second soluble conductor 922. The fourth conductor 923 is connected to the other end of the second soluble conductor 922. In the example shown, the front end of the fourth conductor 923 is fixed to the rear end of the second soluble conductor 922. Specifically, the upper surface of the front end of the fourth conductor 923 is connected to the lower surface of the rear end of the second soluble conductor 922. The second soluble conductor 922 is arranged on the upper side of the third conductor 921 and the fourth conductor 923 and is bridged between them.

[0423] The first terminal 30 and the third conductor 921 are connected. In the example shown in the figure, the rear end of the first terminal 30 is fixed to the front end of the third conductor 921. Specifically, the upper surface of the rear end of the first terminal 30 and the lower surface of the front end of the third conductor 921 are connected to each other. The second terminal 40 and the fourth conductor 923 are connected. In the example shown in the figure, the front end of the second terminal 40 is fixed to the rear end of the fourth conductor 923. Specifically, the upper surface of the front end of the second terminal 40 and the lower surface of the rear end of the fourth conductor 923 are connected to each other.

[0424] The third conductor 921 includes an inner plate portion 21A connected to the second fusible conductor 922 and a third buffer portion 925 arranged in the first buffer space 951 so as to be surrounded by the first filler 71 and to relieve physical stress. In the example shown in the figure, each of the first buffer portion 715 and the third buffer portion 925 is arranged in the first buffer space 951 so as to be surrounded by the first filler 71.

[0425] The inner plate portion 21A has a plate shape extending in a plane direction (XY plane direction) perpendicular to the up-down direction. The rear end portion of the inner plate portion 21A is connected to the front end portion of the second fusible conductor 922 by soldering or the like.

[0426] The third buffer portion 925 is disposed between the front end of the inner plate portion 21A and the rear end of the first terminal 30. The third buffer portion 925 includes a first extension portion 25A extending upward from the front end of the inner plate portion 21A, a second extension portion 25B extending forward from the upper end of the first extension portion 25A, a third extension portion 25C extending downward from the front end of the second extension portion 25B, and a fourth extension portion 25D extending forward from the lower end of the third extension portion 25C. The lower surface of the fourth extension portion 25D is connected to the upper surface of the rear end (conductor connection portion 33) of the first terminal 30. For example, the fourth extension portion 25D is connected to the conductor connection portion 33 of the first terminal 30 by soldering or the like.

[0427] In the illustrated example, the third buffer portion 925 has a curved shape that protrudes upward. In other words, the third buffer portion 925 has a hat shape that protrudes upward when viewed from the left and right. The third buffer portion 925 is not limited to the above, and may have a curved shape that protrudes downward. For example, the third buffer portion 925 may have a crank shape when viewed from the left and right. For example, the shape of the third buffer portion 925 can be changed according to design specifications.

[0428] The fourth conductor 923 includes an inner plate portion 23A connected to the second fusible conductor 922 and a fourth buffer portion 926 arranged in the second buffer space 952 so as to be surrounded by the second filler 72 and mitigating physical stress. In the example shown in the figure, each of the second buffer portion 716 and the fourth buffer portion 926 is arranged in the second buffer space 952 so as to be surrounded by the second filler 72.

[0429] The inner plate portion 23A has a plate shape extending in a plane direction (XY plane direction) perpendicular to the up-down direction. The front end portion of the inner plate portion 23A is connected to the rear end portion of the second fusible conductor 922 by soldering or the like.

[0430] The fourth buffer portion 926 is disposed between the rear end of the inner plate portion 23A and the front end of the second terminal 40. The fourth buffer portion 926 includes a first extension portion 26A extending upward from the rear end of the inner plate portion 23A, a second extension portion 26B extending rearward from the upper end of the first extension portion 26A, a third extension portion 26C extending downward from the rear end of the second extension portion 26B, and a fourth extension portion 26D extending rearward from the lower end of the third extension portion 26C. The lower surface of the fourth extension portion 26D is connected to the upper surface of the front end (conductor connection portion 43) of the second terminal 40. For example, the fourth extension portion 26D is connected to the conductor connection portion 43 of the second terminal 40 by soldering or the like.

[0431] In the illustrated example, the fourth buffer portion 926 has a curved shape that protrudes upward. In other words, the fourth buffer portion 926 has a hat shape that protrudes upward when viewed from the left and right. The fourth buffer portion 926 is not limited to the above shape, and may have a curved shape that protrudes downward. For example, the fourth buffer portion 926 may have a crank shape when viewed from the left and right. For example, the shape of the fourth buffer portion 926 can be changed according to design specifications.

[0432] The insulating member 990 is plate-shaped, with a pair of plate surfaces facing the vertical direction. In the example shown in the figure, the insulating member 990 is a rectangular plate whose left-right dimension is smaller than its front-to-back dimension when viewed from the vertical direction. For example, the insulating member 990 is made of a resin with a tracking resistance index CTI of 500 V or more. For example, the insulating member 990 is made of a polyamide-based resin material or a fluorine-based resin material. Examples of resin materials that make up the insulating member 990 are the same as those used for the insulating case 750 (cover 750D and each holding member) described above.

[0433] The insulating member 990 has a first opposing surface 991 that is in close proximity to or in contact with the first fuse element 710, and a second opposing surface 992 that is in close proximity to or in contact with the second fuse element 920. In the example shown in the figure, the lower surface of the insulating member 990 corresponds to the first opposing surface 991, and the upper surface of the insulating member 990 corresponds to the second opposing surface 992.

[0434] Although not shown, the insulating member 990 may have a slit portion that opens in the vertical direction and extends in the horizontal direction, located further outward in the front-to-rear direction than the fusible conductor. The slit portion extends in a direction perpendicular to the current flow direction (approximately the front-to-rear direction) through the fuse elements 710, 920. When the slit portion is formed in the insulating member 990, molten spatter that adheres to the first opposing surface 991 and the second opposing surface 992 of the insulating member 990 after the fuse elements 710, 920 are interrupted becomes discontinuous at the slit portion, thereby suitably increasing the insulation resistance between the first terminal 30 and the second terminal 40 after the interruption.

[0435] The insulating case 950 is formed with a first buffer space 951 around the first buffer section 715 and the third buffer section 925, a second buffer space 952 around the second buffer section 716 and the fourth buffer section 926, a first element accommodating space 953A in a region other than the region around the first buffer section 715 of the first fuse element 710 and other than the region around the second buffer section 716, a second element accommodating space 953B in a region other than the region around the third buffer section 925 of the second fuse element 920 and other than the region around the fourth buffer section 926, and an internal pressure buffering space 755 that communicates with each of the first element accommodating space 953A and the second element accommodating space 953B via leak holes 754 and / or gaps. The insulating case 950 is configured to be in close proximity to or in contact with areas of the first fuse element 710 other than the area around the first buffer portion 715 and the area around the second buffer portion 716, and areas of the second fuse element 920 other than the area around the third buffer portion 925 and the area around the fourth buffer portion 926.

[0436] The insulating case 950 comprises a first holding member 750A in which at least a first buffer space 951 is formed, a second holding member 950B in which an internal pressure buffer space 755 is formed, a third holding member 950C that shields the open surface 756 of the internal pressure buffer space 755, and a cover 750D that is inserted from a direction perpendicular to the direction in which the first holding member 750A, the second holding member 950B, and the third holding member 950C are stacked.

[0437] The first holding member 750A is disposed below the first terminal 30, the second terminal 40, and the first fuse element 710. The first holding member 750A includes a terminal mounting surface 757, a terminal locking portion 758, and a conductor-facing recess 960.

[0438] The conductor-facing recess 960 of the first holding member 750A is a recessed portion recessed downward from the central portion of the upper surface of the first holding member 750A in the front-to-rear direction of the first fuse element 710. The conductor-facing recess 960 of the first holding member 750A is a substantially rectangular hole opening upward. The bottom surface of the conductor-facing recess 960 is flat and faces upward, extending in a plane direction (XY plane direction) perpendicular to the vertical direction. The bottom surface of the conductor-facing recess 960 of the first holding member 750A faces the bottom surface of the first fusible conductor 712.

[0439] The second holding member 950B is disposed above the first terminal 30, the second terminal 40, and the second fuse element 920. The upper surface of the second holding member 950B constitutes the open surface 756 of the internal pressure buffering space 755. The second holding member 950B includes a terminal pressing surface 759 and a conductor-facing recess 960.

[0440] The conductor facing recess 960 of the second holding member 950B is a recessed shape recessed upward from the central portion of the second fuse element 920 in the front-to-rear direction of the lower surface of the second holding member 950B. The conductor facing recess 960 of the second holding member 950B is a substantially rectangular hole opening downward. The bottom surface of the conductor facing recess 960 of the second holding member 950B is a flat surface facing downward and extends in a plane direction (XY plane direction) perpendicular to the up-down direction. The bottom surface of the conductor facing recess 960 of the second holding member 950B faces the upper surface of the second fusible conductor 922.

[0441] The second holding member 950B has a through-hole 965 that opens in the vertical direction. The through-hole 965 is disposed so as to overlap with each of the first buffer space 951 and the second buffer space 952 when viewed from the vertical direction.

[0442] The third holding member 950C has a protrusion 966 that protrudes downward from a portion that extends in a plane perpendicular to the up-down direction and fits into the through-hole 965. The protrusion 966 is arranged to overlap with each of the first buffer space 951 and the second buffer space 952 when viewed from the up-down direction. In the example shown in the figure, a gap is formed between the outer wall surface of the protrusion 966 in the front-to-rear direction and the wall surface that forms the through-hole 965.

[0443] The three holding members 750A, 950B, and 950C are housed in the cover 750D in a combined state lined up in the vertical direction with the insulating member 990 interposed therebetween. The cover 750D holds the three holding members 750A, 950B, and 950C and the insulating member 990 in a fixed state by adhesive or the like.

[0444] When the first holding member 750A, the insulating member 990, the second holding member 950B, and the third holding member 950C are combined, a first buffer space 951 and a second buffer space 952 are formed in the area surrounded by the first holding member 750A, the insulating member 990, the second holding member 950B, and the third holding member 950C. The first buffer space 951 and the second buffer space 952 are each formed by a part of a through-hole 965 formed in the second holding member 950B, and are separated by a part of a protrusion 966 protruding from the third holding member 950C.

[0445] When the above-described members 750A, 790, 950B, and 950C are combined, a first element accommodating space 953A is formed between the first holding member 750A and the insulating member 990. The first fuse element 710 is accommodated in the first element accommodating space 953A. When the above-described members 750A, 790, 950B, and 950C are combined, a second element accommodating space 953B is formed between the second holding member 950B and the insulating member 990. The second element accommodating space 953B accommodates the second fuse element 920.

[0446] A portion of the upper surface of the first holding member 750A (a portion of the surface facing the first element accommodating space 953A) is configured to be in close proximity to or in contact with the lower surface of a portion of the first fuse element 710 other than the periphery of the first buffer portion 715 and other than the periphery of the second buffer portion 716. A first opposing surface 991, which is the lower surface of the insulating member 990, is configured to be in close proximity to or in contact with the upper surface of a portion of the first fuse element 710 other than the periphery of the first buffer portion 715 and other than the periphery of the second buffer portion 716.

[0447] A portion of the lower surface of the second holding member 950B (a portion of the surface facing the second element accommodating space 953B) is configured to be in close proximity to or in contact with the upper surface of a portion of the second fuse element 920 other than the periphery of the third buffer portion 925 and other than the periphery of the fourth buffer portion 926. The second opposing surface 992, which is the upper surface of the insulating member 990, is configured to be in close proximity to or in contact with the lower surface of a portion of the second fuse element 920 other than the periphery of the third buffer portion 925 and other than the periphery of the fourth buffer portion 926.

[0448] When the second holding member 950B and the third holding member 950C are combined together, an internal pressure buffering space 755 is formed between the second holding member 950B and the third holding member 950C. The internal pressure buffering space 755 is a substantially rectangular parallelepiped space, and communicates with each of the first element accommodating space 953A and the second element accommodating space 953B via the leak hole 754 and / or a gap.

[0449] In the illustrated example, the fillers 71 and 72 are filled into portions of the buffer spaces 951 and 952 (in other words, portions of the through-holes 965), respectively, with gaps. For example, first, the second holding member 950B is mounted on the first holding member 750A, and then the fillers 71 and 72 are poured into the buffer spaces 951 and 952 through the through-holes 965 before the third holding member 950C is mounted on the second holding member 950B. At this time, the amounts of the fillers 71 and 72 poured may be adjusted taking into account the volume of the protrusion 966 of the third holding member 950C. Then, the protrusion 966 is inserted into the through-hole 965, and the third holding member 950C is attached to the second holding member 950B. This allows the fillers 71 and 72 to fill portions of the buffer spaces 951 and 952 (in other words, portions of the through-holes 965), respectively, with gaps.

[0450] The fillers 71 and 72 are not limited to being filled with gaps in portions of the buffer spaces 951 and 952, respectively, but may be filled completely without gaps in the buffer spaces 951 and 952, respectively. For example, the fillers 71 and 72 may be disposed in at least portions of the buffer spaces 951 and 952, respectively, so as to surround at least the buffer portions 715, 716, 925, and 926.

[0451] 67 , in this embodiment as well, element accommodating spaces 953A and 953B are formed in the insulating case 950 so that a portion of the insulating case 950 is in close proximity to or in contact with at least a portion of the fuse elements 710 and 920. The rated voltage of the protective element 900 is equal to or less than the value obtained by multiplying the inter-terminal distance D [mm] between the first terminal 30 and the second terminal 40 by the electric field strength 30 [V / mm].

[0452] The protective element 900 of the present embodiment described above can more effectively suppress arc discharge that occurs during high-voltage, large-current interruption compared to when the rated voltage of the protective element 900 exceeds the terminal distance D [mm] multiplied by the electric field strength of 30 [V / mm]. Furthermore, because the space formed between a portion of the fuse element 710, 920 and the insulating case 950 is narrowed, gas, which is one of the sources of arc discharge that occurs during overcurrent interruption, can be eliminated as much as possible around the fuse element 710, 920. Therefore, arc discharge during interruption is suppressed, high-voltage, large-current interruption is possible, and a decrease in insulation resistance after interruption can be suppressed.

[0453] In the protective element 900 of this embodiment, the first buffer portion 715 of the first fuse element 710 and the third buffer portion 925 of the second fuse element 920 are surrounded by the first filler 71, and the second buffer portion 716 of the first fuse element 710 and the fourth buffer portion 926 of the second fuse element 920 are surrounded by the second filler 72. This allows gas, which is one of the sources of arc discharge that occurs during overcurrent interruption, to be eliminated as much as possible from the periphery of each of the first fuse element 710 and the second fuse element 920. This suppresses plasma that is generated by ionization of gas, which is one of the sources of arc discharge, and thereby suppresses arc discharge. In addition, physical stress is alleviated in each of the first buffer portion 715 and the second buffer portion 716 of the first fuse element 710 and the third buffer portion 925 and the fourth buffer portion 926 of the second fuse element 920. Therefore, expansion / contraction and deformation due to the difference in thermal expansion between the first fuse element 710, the second fuse element 920, the insulating member 990 and the insulating case 950 can be more effectively alleviated.

[0454] Tenth Embodiment A protection element 1000 according to a tenth embodiment of the present invention will be described with reference to Fig. 69. The protection element 1000 of the tenth embodiment differs from the aforementioned ninth embodiment mainly in that it includes a heating element 80 and a power supply member 881. Note that in the drawings of this embodiment, components that are the same or substantially the same as those in the seventh to ninth embodiments may be given the same reference numerals or names and descriptions thereof may be omitted.

[0455] 69, the protective element 1000 includes a first fuse element 710, a first terminal 30 and a second terminal 40 connected to both ends of the first fuse element 710 in the current-carrying direction, a heating element 80, a power supply member 881 (not shown in FIG. 69) connected to the heating element 80, a second fuse element 920 arranged in parallel with the first fuse element 710 and connected to the first terminal 30 and the second terminal 40, an insulating member 990 arranged between the first fuse element 710 and the second fuse element 920, and an insulating case 1050 that houses a portion of the first terminal 30 and the second terminal 40, the first fuse element 710 and the second fuse element 920, the heating element 80, a portion of the power supply member 881, and the insulating member 990.

[0456] The protective element 1000 of this embodiment has a mechanism for interrupting the current path, which includes an overcurrent interruption mechanism in which the fuse elements 710, 920 melt and interrupt the current path when an overcurrent (current equal to or greater than a predetermined value) exceeding the rated current flows through the fuse elements 710, 920, and an active interruption mechanism in which, when an abnormality other than an overcurrent occurs, a current is passed through the heating element 80, causing it to generate heat, thereby melting the fuse elements 710, 920 and interrupting the current path.

[0457] In this embodiment, the portions to which the soluble conductors 712, 922 are connected in each fuse element 710, 920 are opposite to those in the third embodiment described above. Specifically, in the first fuse element 710, the upper surface of the rear end of the first conductor 711 is connected to the lower surface of the front end of the first soluble conductor 712, and the upper surface of the front end of the second conductor 713 is connected to the lower surface of the rear end of the first soluble conductor 712. On the other hand, in the second fuse element 920, the lower surface of the rear end of the third conductor 921 is connected to the upper surface of the front end of the second soluble conductor 922, and the lower surface of the front end of the fourth conductor 923 is connected to the upper surface of the rear end of the second soluble conductor 922.

[0458] In the example shown in the figure, a pair of conductor-facing recesses 1060 are formed in the insulating member 990 in the vertical direction. Of the pair of conductor-facing recesses 1060, the first soluble conductor 712 is arranged in the lower portion, and the second soluble conductor 922 is arranged in the upper portion. Of the pair of conductor-facing recesses 1060, the lower portion is concave and recessed upward from the center portion of the lower surface of the insulating member 990 in the front-to-back direction, and the upper portion is concave and recessed downward from the center portion of the upper surface of the insulating member 990 in the front-to-back direction. Of the pair of conductor-facing recesses 1060, the bottom surface of the lower portion faces the upper surface of the first soluble conductor 712, and the bottom surface of the upper portion faces the lower surface of the second soluble conductor 922. The pair of conductor-facing recesses 1060 are arranged in the center of the insulating member 990 in the front-to-back direction.

[0459] A pair of heating elements 80 are provided in the vertical direction. The pair of heating elements 80 are arranged so as to overlap each fuse element 710, 920 in the vertical direction. The lower of the pair of heating elements 80 is in contact with the first fuse element 710 in the vertical direction, and the upper of the pair of heating elements 80 is in contact with the second fuse element 920 in the vertical direction. The heating element 80 generates heat when current is passed through the power supply member 881, melting and blowing at least a portion of each fuse element 710, 920. Specifically, the lower of the pair of heating elements 80 is arranged so as to overlap the first fusible conductor 712 in the vertical direction and is stacked in the vertical direction with the rear end of the first conductor 711 and the front end of the second conductor 713, respectively. The upper of the pair of heating elements 80 is arranged so as to overlap the second fusible conductor 922 in the vertical direction and is stacked in the vertical direction with the rear end of the third conductor 921 and the front end of the fourth conductor 923, respectively. The pair of heating elements 80 melt and cut at least a portion of each of the fusible conductors 712, 922 by heat generated by energization.

[0460] In the example shown in the figure, the lower of the pair of heating elements 80 is placed in heating element accommodating portion 1061 formed in first holding member 750A, and the upper one is placed in heating element accommodating portion 1061 formed in second holding member 950B. In other words, the pair of heating elements 80 are housed in insulating case 1050.

[0461] 69 , in this embodiment as well, element accommodating spaces 953A and 953B are formed in the insulating case 1050 so that a portion of the insulating case 1050 is in close proximity to or in contact with at least a portion of the fuse elements 710 and 920. The rated voltage of the protection element 1000 is equal to or less than the value obtained by multiplying the inter-terminal distance D [mm] between the first terminal 30 and the second terminal 40 by the electric field strength of 30 [V / mm].

[0462] The protective element 1000 of the present embodiment described above can more effectively suppress arc discharge that occurs during high-voltage, large-current interruption compared to when the rated voltage of the protective element 1000 exceeds the terminal distance D [mm] multiplied by the electric field strength of 30 [V / mm]. Furthermore, because the space formed between a portion of the fuse element 710, 920 and the insulating case 1050 is narrowed, gas, which is one of the sources of arc discharge that occurs during overcurrent interruption, can be eliminated as much as possible around the fuse element 710, 920. Therefore, arc discharge during interruption is suppressed, high-voltage, large-current interruption is possible, and a decrease in insulation resistance after interruption can be suppressed.

[0463] In the protective element 1000 of this embodiment, when an overcurrent exceeding the rated current (i.e., a current equal to or greater than a predetermined value) flows through the fuse elements 710, 920, the fuse elements 710, 920 generate heat and melt, thereby interrupting the current path. Furthermore, the protective element 1000 can interrupt the current path by passing a current through the heating element 80 to generate heat, thereby melting and blowing the fuse elements 710, 920 stacked on the heating element 80. According to this embodiment, it is possible to prevent a large-sc...

Claims

1. A protective element comprising: a fuse element; a first terminal and a second terminal connected to both ends of the fuse element in the current-carrying direction; and an insulating case that houses a portion of the first terminal and the second terminal and the fuse element, wherein an element housing space is formed in the insulating case so that a portion of the insulating case is in close proximity to or in contact with at least a portion of the fuse element, and the rated voltage of the protective element is equal to or less than the value obtained by multiplying the terminal distance D [mm] between the first and second terminals by an electric field strength of 30 [V / mm].

2. The protection element according to claim 1, wherein the fuse element has a first conductor and a fusible conductor, and the first conductor and the fusible conductor are connected in series in the current-carrying direction.

3. The protective element according to claim 2, wherein the first conductor has a first buffer portion that relieves physical stress, and the insulating case has a first buffer space formed around the first buffer portion.

4. The protection element according to claim 3, wherein the first buffer space is filled with a first filling material.

5. The protective element described in claim 4, wherein the fuse element further has a second conductor, the first conductor is connected to one end of the fusible conductor, and the second conductor is connected to the other end of the fusible conductor, the second conductor has a second buffer section that relieves physical stress, the insulating case has a second buffer space formed around the second buffer section, and the second buffer space is filled with a second filler material.

6. The protection element according to claim 5, wherein the insulating case has an internal pressure buffer space that communicates with the element accommodating space and that allows gas generated when the fuse element interrupts an overcurrent to escape.

7. A protective element as described in claim 6, wherein the internal pressure buffering space is filled with a third filler material, and the leak hole and / or gap connecting the element accommodating space and the internal pressure buffering space is not filled with anything.

8. The protection element according to claim 5, wherein each of the first conductor and the second conductor is a metal plate-shaped member.

9. The protection element according to claim 5, wherein each of the first conductor and the second conductor is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

10. The protective element according to any one of claims 2 to 7, wherein the fusible conductor is made of Sn or a metal containing Sn as a main component.

11. The protection element according to any one of claims 2 to 7, wherein the fusible conductor is a laminate including a high melting point metal layer and a low melting point metal layer.

12. The protective element according to claim 11, wherein the high-melting-point metal layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component, and the low-melting-point metal layer is made of Sn or a metal containing Sn as a main component.

13. A protective element as described in claim 6 or 7, wherein the insulating case comprises: a first holding member in which at least the first buffer space is formed; a second holding member in which the internal pressure buffer space is formed; and a cover inserted from a direction perpendicular to the direction in which the first holding member and the second holding member are stacked.

14. The protection element according to claim 13, further comprising a third holding member on the inside of the cover, the third holding member shielding the open surface of the internal pressure buffering space of the second holding member.

15. The protection element according to claim 5, wherein the first filling material and the second filling material are each made of an elastic resin.

16. The protection element according to claim 15, wherein the elastic resin is a silicone resin.

17. The protective element according to claim 7, wherein the third filler contains at least insulating fiber or silica sand.

18. The protection element according to claim 17, wherein the insulating fiber is ceramic fiber paper.

19. A protection element according to any one of claims 2 to 7, wherein flux is applied to at least one surface of the fusible conductor.

20. A protective element according to any one of claims 1 to 7, wherein the insulating case is made of a polyamide resin or a fluorine resin.

21. A protection element according to any one of claims 1 to 7, wherein a plurality of the fuse elements are provided in parallel.

22. A protection element according to any one of claims 1 to 7, wherein a heating element that melts the fuse element by generating heat is connected to a part of the fuse element.

23. A protection element according to any one of claims 1 to 7, wherein the rated voltage is equal to or greater than the value obtained by multiplying the terminal distance D [mm] by an electric field strength of 15 [V / mm].

24. A protection element according to any one of claims 1 to 7, wherein the rated voltage is equal to or greater than the value obtained by multiplying the terminal distance D [mm] by an electric field strength of 20 [V / mm].

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