Protective element

Abstract

This protective element (1) is provided with: a first fuse element (10); a first terminal (30) and a second terminal (40) that are connected to both ends of the first fuse element (10) in the energization direction; and an insulation case (50) that accommodates parts of the first terminal (30) and second terminal (40) and the first fuse element (10). The first fuse element (10) has a first conductor (11) and a first fusible conductor (12) that are connected in series in the energization direction. The first conductor (11) is provided with a first buffer part (15) that relaxes physical stress. In the insulation case (50), a first buffer space (51) is formed around the first buffer part (15). The protective element (1) further comprises a first filler (71) disposed in the first buffer space (51) so as to surround the first buffer part (15). The insulation case (50) is configured so as to approach or contact a portion other than the periphery of the first buffer part (15) of the first fuse element (10).

Description

Protection Elements

[0001] The present invention relates to a protection element. The present invention claims priority to Japanese Patent Application No. 2023-124363, filed on July 31, 2023, the contents of which are incorporated herein by reference.

[0002] Conventionally, there are fuse elements that generate heat and melt to interrupt a current path when a current exceeding the rated value flows through the current path. 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] The following technologies are known for forming heat spots in a foil-shaped fuse element by using holes, thickness variations, notches, etc., to melt the fuse element in the event of an overcurrent. For example, Patent Document 1 discloses a fuse in which the thickness of the interrupting portion of a conductive thin-film pattern formed on an insulating substrate is set to be thinner than the thickness of the connecting portions connected in series to the interrupting portion. For example, Patent Documents 2 and 3 disclose fuse elements in which the fusing portion is formed by punching holes in multiple elements arranged in parallel. For example, Patent Documents 4 and 5 disclose fuses in which the thickness of the interrupting portion, in a conductive thin-film pattern formed on the surface of an insulating substrate, is thinner than the thickness of the connecting bands connected in series to the interrupting portion.

[0005] Japanese Patent No. 6057413 Japanese Patent No. 6199368 Japanese Patent No. 5952751 Japanese Patent No. 5116119 Japanese Patent No. 4998890

[0006] 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 have lower resistance (shorter length), the fuse element's fusion zone is often made wider and thicker. In this case, molten debris continuously adheres to the surface of the arc-extinguishing agent, forming a conductive path that is likely to degrade the interruption characteristics. There is also concern that this increases the risk of a decrease in insulation resistance after interruption.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a protection element that suppresses arc discharge during interruption, is capable of interrupting high voltages and large currents, and can suppress a decrease in insulation resistance after interruption.

[0008] In order to solve the above problems, the present invention provides the following means.

[0009] [Aspect 1] A protective element comprising: a first fuse element; a first terminal and a second terminal connected to both ends of the first fuse element in the current flow direction; and an insulating case that accommodates a portion of the first terminal and the second terminal and the first fuse element, wherein the first fuse element has a first conductor and a first fusible conductor connected in series in the current flow direction of the first fuse element, the first conductor having a first buffer portion that relieves physical stress, a first buffer space formed around the first buffer portion in the insulating case, and a first filler arranged in the first buffer space to surround the first buffer portion, and the insulating case is configured to be in close proximity to or in contact with a portion of the first fuse element other than the periphery of the first buffer portion.

[0010] [Aspect 2] The first fuse element further has a second conductor connected in series with the first soluble conductor in the current flow direction of the first fuse element, the first conductor is connected to one end of the first soluble conductor, the second conductor is connected to the other end of the first soluble conductor, the first terminal is connected to the first conductor, and the second terminal is connected to the second conductor, the second conductor has a second buffer portion that relieves physical stress, a second buffer space is formed around the second buffer portion in the insulating case, and a second filler is arranged in the second buffer space to surround the second buffer portion, A protective element as described in Aspect 1.

[0011] [Aspect 3] A protective element as described in Aspect 1 or 2, wherein the insulating case has an element accommodating space formed in a portion other than the periphery of the first buffer portion of the first fuse element, and an internal pressure buffering space connected to the element accommodating space via a leak hole and / or gap, and further comprises a third filler material arranged in at least a portion of the internal pressure buffering space.

[0012] [Aspect 4] A protective element as described in Aspect 2, wherein each of the first conductor and the second conductor is a metal plate-shaped member, and the insulating case is configured to be in close proximity to or in contact with the surface and back surfaces of the plate-shaped members other than the periphery of the first buffer portion of the first conductor and other than the periphery of the second buffer portion of the second conductor.

[0013] [Aspect 5] The protective element according to aspect 2 or 4, 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.

[0014] [Aspect 6] The protection element according to any one of aspects 1 to 5, wherein the first fusible conductor is made of Sn or a metal mainly composed of Sn.

[0015] [Aspect 7] The protection element according to any one of aspects 1 to 6, wherein the first fusible conductor is a laminate including a high melting point metal layer and a low melting point metal layer.

[0016] [Aspect 8] A protective element according to aspect 7, wherein the high-melting-point metal layer is made of Ag or Cu, or a metal primarily composed of Ag or Cu, and the low-melting-point metal layer is made of Sn or a metal primarily composed of Sn.

[0017] [Aspect 9] The insulating case comprises at least a first retaining member in which the first buffer space is formed, a second retaining member in which the internal pressure buffer space is formed, a third retaining member that shields the open surface of the internal pressure buffer space, and a cover that is inserted from a direction perpendicular to the direction in which the first retaining member, the second retaining member, and the third retaining member are stacked.This is a protective element described in Aspect 3.

[0018] [Aspect 10] The protective element according to Aspect 2, wherein each of the first filler and the second filler is made of an elastic resin.

[0019] [Aspect 11] The protective element according to aspect 10, wherein the elastic resin is a silicone resin or a photocurable acrylic resin.

[0020] [Aspect 12] The protective element according to Aspect 3, wherein the third filler includes at least insulating fiber or silica sand.

[0021] [Aspect 13] The protective element according to aspect 12, wherein the insulating fiber is ceramic fiber paper.

[0022] [Aspect 14] The protective element according to any one of aspects 1 to 13, wherein flux is applied to at least one surface of the first fusible conductor.

[0023] [Aspect 15] A protective element according to any one of Aspects 1 to 14, wherein the insulating case is made of a polyamide resin or a fluorine-based resin.

[0024] [Aspect 16] A protective element comprising: a first fuse element; a first terminal and a second terminal connected to both ends of the first fuse element in the current flow direction; a heating element; a power supply member connected to the heating element; a portion of the first terminal and the second terminal; the first fuse element; the heating element; and an insulating case that houses a portion of the power supply member, wherein the first fuse element has a first conductor and a first fusible conductor connected in series in the current flow direction of the first fuse element, the first conductor having a first buffer portion that relieves physical stress, the insulating case forming a first buffer space around the first buffer portion, and further comprising a first filler arranged in the first buffer space to surround the first buffer portion, and the insulating case is configured to be in close proximity to or in contact with a portion of the first fuse element other than the periphery of the first buffer portion.

[0025] [Aspect 17] The first fuse element further has a second conductor connected in series with the first soluble conductor in the current flow direction of the first fuse element, the first conductor is connected to one end of the first soluble conductor, the second conductor is connected to the other end of the first soluble conductor, the first terminal is connected to the first conductor, and the second terminal is connected to the second conductor, the second conductor has a second buffer portion that relieves physical stress, a second buffer space is formed around the second buffer portion in the insulating case, and a second filler is arranged in the second buffer space to surround the second buffer portion, A protective element as described in Aspect 16.

[0026] [Aspect 18] A protective element as described in Aspect 16 or 17, wherein the insulating case has an element accommodating space formed in a region other than the periphery of the first buffer portion of the first fuse element, and an internal pressure buffering space connected to the element accommodating space via a leak hole and / or gap, and further comprises a third filler material arranged in at least a portion of the internal pressure buffering space.

[0027] [Aspect 19] A protective element as described in Aspect 17, wherein each of the first conductor and the second conductor is a metal plate-shaped member, and the insulating case is configured to be in close proximity to or in contact with the surface and back surfaces of the plate-shaped members other than the periphery of the first buffer portion of the first conductor and other than the periphery of the second buffer portion of the second conductor.

[0028] [Aspect 20] The protective element according to aspect 17 or 19, 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.

[0029] [Aspect 21] The protection element according to any one of aspects 16 to 20, wherein the first fusible conductor is made of Sn or a metal mainly composed of Sn.

[0030] [Aspect 22] The protection element according to any one of aspects 16 to 21, wherein the first fusible conductor is a laminate including a high melting point metal layer and a low melting point metal layer.

[0031] [Aspect 23] A protective element according to aspect 22, wherein the high-melting-point metal layer is made of Ag or Cu, or a metal primarily composed of Ag or Cu, and the low-melting-point metal layer is made of Sn or a metal primarily composed of Sn.

[0032] [Aspect 24] The insulating case comprises at least a first retaining member in which the first buffer space is formed, a second retaining member in which the internal pressure buffer space is formed, a third retaining member that shields the open surface of the internal pressure buffer space, and a first cover and a second cover that are inserted from both directions perpendicular to the direction in which the first retaining member, the second retaining member, and the third retaining member are stacked, as described in Aspect 18.

[0033] [Aspect 25] The protective element according to aspect 17, wherein each of the first filler and the second filler is made of an elastic resin.

[0034] [Aspect 26] The protective element according to aspect 25, wherein the elastic resin is a silicone resin or a photocurable acrylic resin.

[0035] [Aspect 27] The protective element according to aspect 18, wherein the third filler includes at least insulating fiber or silica sand.

[0036] [Aspect 28] The protective element according to aspect 27, wherein the insulating fiber is ceramic fiber paper.

[0037] [Aspect 29] The protection element according to any one of aspects 16 to 28, wherein flux is applied to at least one surface of the first fusible conductor.

[0038] [Aspect 30] A protective element according to any one of Aspects 16 to 29, wherein the insulating case is made of a polyamide resin or a fluorine-based resin.

[0039] [Aspect 31] A protection element as described in Aspect 1, comprising: a second fuse element arranged in parallel with the first fuse element and connected to the first terminal and the second terminal; and an insulating member arranged between the first fuse element and the second fuse element, having a first opposing surface that is in close proximity to or contact with the first fuse element and a second opposing surface that is in close proximity to or contact with the second fuse element, wherein the second fuse element has a third conductor and a second fusible conductor connected in series in the current flow direction of the second fuse element, the third conductor is arranged in the first buffer space so as to be surrounded by the first filler and has a third buffer portion that relieves physical stress, and the insulating case is configured to be in close proximity to or contact with a portion of the second fuse element other than the periphery of the third buffer portion.

[0040] [Aspect 32] The first fuse element further has a second conductor connected in series with the first soluble conductor in the current flow direction of the first fuse element, the first conductor is connected to one end of the first soluble conductor, the second conductor is connected to the other end of the first soluble conductor, the first terminal is connected to the first conductor, and the second terminal is connected to the second conductor, the second conductor has a second buffer portion that relieves physical stress, a second buffer space is formed in the insulating case around the second buffer portion, and a second filler is arranged in the second buffer space to surround the second buffer portion, A protective element as described in Aspect 31.

[0041] [Aspect 33] The second fuse element further has a fourth conductor connected in series with the second soluble conductor in the current flow direction of the second fuse element, the third conductor is connected to one end of the second soluble conductor, the fourth conductor is connected to the other end of the second soluble conductor, the first terminal is connected to the third conductor, and the second terminal is connected to the fourth conductor, and the fourth conductor is arranged in the second buffer space so as to be surrounded by the second filler, and is provided with a fourth buffer portion that relieves physical stress. A protective element as described in Aspect 32.

[0042] [Aspect 34] A protective element described in any one of Aspects 31 to 33, wherein the insulating case has a first element accommodating space formed in a region other than the periphery of the first buffer portion of the first fuse element, and an internal pressure buffering space connected to the first element accommodating space via a leak hole and / or gap, and further comprises a third filler material arranged in at least a portion of the internal pressure buffering space.

[0043] [Aspect 35] A protective element as described in Aspect 34, in which a second element accommodating space is formed in the insulating case in a region other than the periphery of the third buffer portion of the second fuse element, and the second element accommodating space is connected to the internal pressure buffering space via the leak hole and / or gap.

[0044] [Aspect 36] A protection element as described in Aspect 16, comprising: a second fuse element arranged in parallel with the first fuse element and connected to the first terminal and the second terminal; and an insulating member arranged between the first fuse element and the second fuse element, having a first opposing surface that is in close proximity to or contact with the first fuse element and a second opposing surface that is in close proximity to or contact with the second fuse element, wherein the second fuse element has a third conductor and a second fusible conductor connected in series in the current flow direction of the second fuse element, the third conductor is arranged in the first buffer space so as to be surrounded by the first filler and has a third buffer portion that relieves physical stress, and the insulating case is configured to be in close proximity to or contact with a portion of the second fuse element other than the periphery of the third buffer portion.

[0045] [Aspect 37] The first fuse element further has a second conductor connected in series with the first soluble conductor in the current flow direction of the first fuse element, the first conductor is connected to one end of the first soluble conductor, the second conductor is connected to the other end of the first soluble conductor, the first terminal is connected to the first conductor, and the second terminal is connected to the second conductor, the second conductor has a second buffer portion that relieves physical stress, a second buffer space is formed in the insulating case around the second buffer portion, and a second filler is arranged in the second buffer space to surround the second buffer portion, A protective element as described in Aspect 36.

[0046] [Aspect 38] The second fuse element further has a fourth conductor connected in series with the second soluble conductor in the current flow direction of the second fuse element, the third conductor is connected to one end of the second soluble conductor, the fourth conductor is connected to the other end of the second soluble conductor, the first terminal is connected to the third conductor, and the second terminal is connected to the fourth conductor, and the fourth conductor is arranged in the second buffer space so as to be surrounded by the second filler, and is provided with a fourth buffer portion that relieves physical stress, A protective element as described in Aspect 37.

[0047] [Aspect 39] A protective element described in any one of Aspects 36 to 38, wherein the insulating case has a first element accommodating space formed in a region other than the periphery of the first buffer portion of the first fuse element, and an internal pressure buffering space connected to the first element accommodating space via a leak hole and / or gap, and further comprises a third filler material arranged in at least a portion of the internal pressure buffering space.

[0048] [Aspect 40] A protective element as described in Aspect 39, in which a second element accommodating space is formed in the insulating case in a region other than the periphery of the third buffer portion of the second fuse element, and the second element accommodating space is connected to the internal pressure buffering space via the leak hole and / or gap.

[0049] According to the present invention, it is possible 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.

[0050] 10 is a cross-sectional view of a protection element according to a first embodiment taken along line II-II of FIG. 1; a cross-sectional view of a protection element according to a first embodiment taken along line II-II of FIG. 1; a side view of a protection element according to a first embodiment taken along line III of FIG. 2; a cross-sectional view of a protection element according to a second embodiment taken along line VI-VI of FIG. 7; a cross-sectional view of a protection element according to a second embodiment taken along line VII-VII of FIG. 6; a side view of a protection element according to a second embodiment taken along line VIII of FIG. 7; a cross-sectional view of a protection element according to a third embodiment taken along line IX-IX of FIG. 6; a cross-sectional view of a protection element according to a third embodiment taken along line XI-XI of FIG. 10; a cross-sectional view of a protection element according to a fourth embodiment taken along line VI-VI of FIG. 7;

[0051] Hereinafter, the embodiments will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for the sake of clarity, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate changes can be made within the scope of the effects of the present invention.

[0052] First Embodiment A protection element according to one embodiment of the present invention will be described with reference to Figures 1 to 5. The protection element according to this embodiment constitutes a 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, for example, on an electric vehicle (EV).

[0053] 1 to 5 , the protective device 1 includes a first fuse element 10, a first terminal 30 and a second terminal 40 connected to both ends of the first fuse element 10 in the current-carrying direction, and an insulating case 50 that houses a portion of the first terminal 30 and a portion of the second terminal 40 and the first fuse element 10. 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.

[0054] The protection element 1 has an overcurrent interruption mechanism that cuts off the current path when an overcurrent (current greater than a specified value) that exceeds the rated current flows through the first fuse element 10, causing the first fuse element 10 to melt and cut off the current path.

[0055] 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 device 1 is in use, so it may also be referred to as the current flow direction.

[0056] 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.

[0057] 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 1 is viewed from the rear (+X side), and the +Y side is the right side when the protective element 1 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.

[0058] 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.

[0059] (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.

[0060] The rear end of the first terminal 30 is connected to the front end of the first fuse element 10. The front portion of the first terminal 30 protrudes forward from the insulating case 50 and is exposed to the outside of the insulating case 50. The front end of the second terminal 40 is connected to the rear end of the first fuse element 10. The rear portion of the second terminal 40 protrudes rearward from the insulating case 50 and is exposed to the outside of the insulating case 50.

[0061] The first terminal 30 comprises a terminal body 31 having an external terminal hole 32 formed therein, a conductor connection portion 33 connected to the front end portion of the first fuse element 10, and a locking claw 34 that is locked to the terminal locking portion 58 of the insulating case 50.

[0062] The terminal body 31 is a rectangular plate-like member that is elongated in the front-rear direction. The rear portion of the terminal body 31 is disposed between the terminal mounting surface 57 and the terminal pressing surface 59 at the front of the insulating case 50, and is sandwiched between the terminal mounting surface 57 and the terminal pressing surface 59. 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 10 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.

[0063] The second terminal 40 comprises a terminal body 41 having an external terminal hole 42 formed therein, a conductor connection portion 43 connected to the rear end portion of the first fuse element 10, and a locking claw 44 that is locked to the terminal locking portion 58 of the insulating case 50.

[0064] 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 57 and the terminal pressing surface 59 at the rear of the insulating case 50, and is sandwiched between the terminal mounting surface 57 and the terminal pressing surface 59. 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 10 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 both the left and right ends of the conductor connecting portion 43.

[0065] 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.

[0066] 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.

[0067] (First Fuse Element) The first fuse element 10 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 10 is provided, but this is not limited to this. For example, two first fuse elements 10 may be provided side by side in the vertical direction, or three or more first fuse elements 10 may be provided side by side. For example, the installation mode of the first fuse element 10 can be changed depending on the design specifications.

[0068] The first fuse element 10 has a first conductor 11, a first fusible conductor 12, and a second conductor 13 connected in series in the current-carrying direction. For example, the first fusible conductor 12 is made of a material having a lower melting temperature than each of the first conductor 11 and the second conductor 13. For example, the first fusible conductor 12 has a higher electrical resistivity than each of the first conductor 11 and the second conductor 13. The first fusible conductor 12 functions as a melting portion of the first fuse element 10 when an overcurrent is interrupted.

[0069] The first soluble conductor 12 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 in the figure, the first soluble conductor 12 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 soluble conductor 12 is disposed in the center of the first fuse element 10 in the front-to-back direction. In this embodiment, flux 75 is applied to at least one surface of the first soluble conductor 12.

[0070] For example, the first soluble conductor 12 is made of Sn (tin) or a metal mainly composed of Sn. Although not shown, the first soluble conductor 12 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 layer being 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.

[0071] 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.

[0072] 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.

[0073] The laminate may have a two-layer structure of a low-melting-point metal layer / a high-melting-point metal layer. Or, 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. In addition, the first soluble conductor 12 may be composed of a single layer of a low-melting-point metal layer containing Sn.

[0074] Each of the first conductor 11 and the second conductor 13 is plate-shaped, sheet-shaped, or foil-shaped. In this embodiment, each of the first conductor 11 and the second conductor 13 is a metal plate-shaped member. In the example shown in the figure, each of the first conductor 11 and the second conductor 13 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 11 and the second conductor 13 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.

[0075] The first conductor 11, the first soluble conductor 12, and the second conductor 13 are connected in series in this order to form a current path of the first fuse element 10. Each of the first conductor 11 and the second conductor 13 is connected to an end of the first soluble conductor 12 in the current direction in which current flows through the first fuse element 10 (approximately the front-to-back direction in the example shown in the figure).

[0076] The first conductor 11 is connected to one end of the first soluble conductor 12. In the example shown in the figure, the rear end of the first conductor 11 is fixed on the front end of the first soluble conductor 12. That is, the lower surface of the rear end of the first soluble conductor 11 is connected to the upper surface of the front end of the first soluble conductor 12. The second conductor 13 is connected to the other end of the first soluble conductor 12. In the example shown in the figure, the front end of the second conductor 13 is fixed on the rear end of the first soluble conductor 12. That is, the lower surface of the front end of the second conductor 13 is connected to the upper surface of the rear end of the first soluble conductor 12. The first soluble conductor 12 is arranged on the lower side of the first conductor 11 and the second conductor 13 and is bridged between them. Note that the vertical relationship of the connection between the first soluble conductor 12 and the first conductor 11 and the second conductor 13 is not limited, and the first soluble conductor 12 may be arranged on the upper side of the first conductor 11 and the second conductor 13.

[0077] The first terminal 30 and the first conductor 11 are connected. In the illustrated example, the rear end of the first terminal 30 is fixed onto the front end of the first conductor 11. 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 11 are connected to each other. The second terminal 40 and the second conductor 13 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 13. 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 13 are connected to each other. Note that the vertical relationship between the first terminal 30 and the first conductor 11 and the vertical relationship between the second terminal 40 and the second conductor 13 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 11 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 13 may be connected to each other.

[0078] The first conductor 11 has an inner plate portion 11A connected to the first fusible conductor 12 and a first buffer portion 15 that relieves physical stress.

[0079] 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 soluble conductor 12 by soldering or the like.

[0080] The first buffer portion 15 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 15 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.

[0081] In the illustrated example, the first buffer section 15 has a curved shape that protrudes downward. In other words, the first buffer section 15 has a hat shape that protrudes downward when viewed from the left-right direction. The first buffer section 15 is not limited to the above, and may have a curved shape that protrudes upward. For example, the first buffer section 15 may have a crank shape when viewed from the left-right direction. For example, the shape of the first buffer section 15 can be changed according to design specifications.

[0082] The second conductor 13 includes an inner plate portion 13A connected to the first fusible conductor 12 and a second buffer portion 16 that relieves physical stress.

[0083] 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 soluble conductor 12 by soldering or the like.

[0084] The second buffer portion 16 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 16 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.

[0085] In the illustrated example, the second buffer section 16 has a curved shape that protrudes downward. In other words, the second buffer section 16 has a hat shape that protrudes downward when viewed from the left and right. The second buffer section 16 is not limited to the above shape, and may have a curved shape that protrudes upward. For example, the second buffer section 16 may have a crank shape when viewed from the left and right. For example, the shape of the second buffer section 16 can be changed according to design specifications.

[0086] (Insulating Case) The insulating case 50 has an overall columnar shape extending in the front-to-rear direction. The insulating case 50 is formed with a first buffer space 51 around the first buffer section 15, a second buffer space 52 around the second buffer section 16, an element accommodating space 53 in a region of the first fuse element 10 other than the region around the first buffer section 15 and the region around the second buffer section 16, and an internal pressure buffering space 55 that communicates with the element accommodating space 53 via a leak hole and / or gap 54. The insulating case 50 is configured to be in close proximity to or in contact with a region of the first fuse element 10 other than the region around the first buffer section 15 and the region around the second buffer section 16.

[0087] The insulating case 50 includes a first holding member 50A in which at least a first buffer space 51 is formed, a second holding member 50B in which an internal pressure buffer space 55 is formed, a third holding member 50C that shields an open surface 56 of the internal pressure buffer space 55, and a cover 50D that is inserted from a direction perpendicular to the stacking direction of the first holding member 50A, the second holding member 50B, and the third holding member 50C. Note that the first buffer space 51 may be formed in the second holding member 50B instead of the first holding member 50A.

[0088] The first holding member 50A 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 10. The first holding member 50A includes a terminal mounting surface 57, a terminal locking portion 58, and a conductor-facing recess 60.

[0089] The terminal mounting surface 57 is concave and recessed downward from the top surface of the first holding member 50A. The bottom surface of the terminal mounting surface 57 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 57 are provided on the first holding member 50A. The pair of terminal mounting surfaces 57 are located at both ends of the first holding member 50A in the front-to-rear direction.

[0090] The terminal locking portions 58 are arranged on side walls that stand on the outer left-right portions of the first holding member 50A. The terminal locking portions 58 are groove-shaped and extend in the vertical direction (in other words, concave and recessed outward in the left-right direction). The terminal locking portions 58 are wall surfaces that run along the top surface of the first holding member 50A and the openings of the side walls that face inward in the left-right direction. A pair of terminal locking portions 58 (i.e., four in total) are arranged on each of the front-rear end portions of the first holding member 50A.

[0091] The conductor facing recess 60 is a recessed portion recessed downward from the central portion of the upper surface of the first holding member 50A in the front-to-back direction of the first fuse element 10. The conductor facing recess 60 is a substantially rectangular hole opening upward. The bottom surface of the conductor facing recess 60 is a flat surface facing upward and extends in a plane direction (XY plane direction) perpendicular to the vertical direction. The bottom surface of the conductor facing recess 60 faces the lower surface of the first soluble conductor 12. The conductor facing recess 60 is arranged on the central side of the first holding member 50A in the front-to-back direction. The dimension of the conductor facing recess 60 in the front-to-back direction is larger than the dimension of the first soluble conductor 12 in the front-to-back direction. The conductor facing recess 60 may be formed on the second holding member 50B side facing the first fuse element 10.

[0092] The second holding member 50B is located in the vertical center of the three holding members. The second holding member 50B is located above the first terminal 30, the second terminal 40, and the first fuse element 10. The upper surface of the second holding member 50B forms the open surface 56 of the internal pressure buffering space 55. The second holding member 50B has a terminal pressing surface 59.

[0093] The terminal pressing surface 59 is concave and recessed upward from the lower surface of the second holding member 50B. The bottom surface of the terminal pressing surface 59 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 59 is provided on the second holding member 50B. The pair of terminal pressing surfaces 59 is disposed at both ends of the second holding member 50B in the front-to-rear direction. Note that the terminal pressing surface 59 may be formed on the side of the first holding member 50A facing the first terminals 30 and the second terminals 40.

[0094] The third holding member 50C is the uppermost of the three holding members. The third holding member 50C has a shape that extends in a plane direction perpendicular to the up-down direction. The lower surface of the third holding member 50C is flat and aligned with the upper surface (open surface 56) of the second holding member 50B.

[0095] The cover 50D has a cylindrical shape that extends in the front-to-rear direction. In the example shown in the figure, the cover 50D has a cylindrical shape that opens in the front-to-rear direction. The three holding members 50A, 50B, and 50C are housed inside the cover 50D in a combined state lined up in the vertical direction. The cover 50D holds the three holding members 50A, 50B, and 50C in a fixed state by adhesive or the like.

[0096] When the first holding member 50A and the second holding member 50B are combined together, a first buffer space 51, a second buffer space 52, and an element accommodating space 53 are formed between the first holding member 50A and the second holding member 50B. The element accommodating space 53 accommodates the first fuse element 10.

[0097] A portion of the upper surface of the first holding member 50A (a portion of the surface facing the element accommodating space 53) is configured to be in close proximity to or in contact with the lower surface of a portion of the first fuse element 10 other than the periphery of the first buffer portion 15 and other than the periphery of the second buffer portion 16. A portion of the lower surface of the second holding member 50B (a portion of the surface facing the element accommodating space 53) is configured to be in close proximity to or in contact with the upper surface of a portion of the first fuse element 10 other than the periphery of the first buffer portion 15 and other than the periphery of the second buffer portion 16.

[0098] The first buffer space 51 and the second buffer space 52 are each formed between the inner wall surface of a recess recessed downward from the top surface of the first holding member 50A and the bottom surface of the second holding member 50B. Each of the first buffer space 51 and the second buffer space 52 has a rectangular parallelepiped shape that is elongated in the left-right direction when viewed from the top-bottom direction. The first buffer space 51 is formed in the front end portion of the first holding member 50A. The first buffer space 51 is located between the rear end of the front terminal mounting surface 57 of the first holding member 50A and a portion of the surface facing the front of the element accommodating space 53. The second buffer space 52 is formed in the rear end portion of the first holding member 50A. The second buffer space 52 is located between the front end of the rear terminal mounting surface 57 of the first holding member 50A and a portion of the surface facing the rear of the element accommodating space 53.

[0099] When the second holding member 50B and the third holding member 50C are combined, an internal pressure buffering space 55 is formed between the second holding member 50B and the third holding member 50C. The internal pressure buffering space 55 is a substantially rectangular parallelepiped space that communicates with the element accommodating space 53 via a leak hole and / or gap 54. For example, the vertical dimension of the internal pressure buffering space 55 is between one-third and one-half of the vertical dimension (external height) of the entire protective element 1. The internal pressure buffering space 55 acts to suppress a sudden increase in the internal pressure of the protective element 1 due to gas generated by arc discharge that occurs when the first fuse element 10 melts.

[0100] In the illustrated example, four leak holes and / or gaps 54 are spaced apart in the front-to-rear direction and one pair is spaced apart in the left-to-right direction. The leak holes and / or gaps 54 extend linearly in the up-down direction. For example, the opening area of ​​the leak holes and / or gaps 54 (the cross-sectional area of ​​the leak holes and / or gaps 54 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 50 and the first fuse element 10 are adjacent to or in contact with each other, but is not limited outside the area where the insulating case 50 and the first fuse element 10 are adjacent to or in contact with each other. The configuration of the leak holes and / or gaps 54 (the number, location, shape, opening area, etc.) is not limited to the above and can be changed according to design specifications.

[0101] For example, the cover 50D and each of the holding members 50A, 50B, and 50C 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.

[0102] The cover 50D and the holding members 50A, 50B, and 50C may 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 may deform or the adhesions may aggregate, making the metal particles sparse and making it difficult to form a conduction path.

[0103] Examples of resin materials that can be used include polyamide-based resins and fluorine-based resins. In this embodiment, the insulating case 50 is made of polyamide-based resins or fluorine-based resins. 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) resins. Examples of fluorine-based resins include polytetrafluoroethylene. Furthermore, polyamide-based resins and fluorine-based resins are highly heat-resistant and flammable. In particular, aliphatic polyamides are less likely to produce graphite when burned. Therefore, forming the cover 50D and each retaining member using aliphatic polyamides more reliably prevents the formation of a new current path due to graphite produced by arc discharge when the first fuse element 10 melts.

[0104] (First Filler, Second Filler) The protective element 1 further includes a first filler 71 disposed in the first buffer space 51 to surround the first buffer section 15, and a second filler 72 disposed in the second buffer space 52 to surround the second buffer section 16. 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.

[0105] 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.

[0106] In the illustrated example, the fillers 71 and 72 are respectively filled in the buffer spaces 51 and 52. For example, first, before the second holding member 50B is mounted on the first holding member 50A, the fillers 71 and 72 are respectively placed in the buffer spaces 51 and 52. Thereafter, the second holding member 50B is attached to the first holding member 50A, whereby the fillers 71 and 72 can be respectively filled in the buffer spaces 51 and 52.

[0107] The fillers 71 and 72 do not necessarily have to be completely filled into the buffer spaces 51 and 52, respectively, without leaving gaps, but may be filled with gaps in parts of the buffer spaces 51 and 52, respectively. For example, the fillers 71 and 72 may be disposed in at least parts of the buffer spaces 51 and 52, respectively, so as to surround at least the buffer sections 15 and 16.

[0108] (Third Filler) The protective element 1 further includes a third filler 73 disposed in at least a portion of the internal pressure buffering space 55. 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.

[0109] 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 buffering space 55. 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.

[0110] Silica sand is granular SiO 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.

[0111] 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.

[0112] In the example shown in the figure, the third filler 73 fills the internal pressure buffering space 55 inside the protective element 1. A portion of the third filler 73 contacts the bottom surface of the recess that forms the internal pressure buffering space 55 in the second holding member 50B located above the first fuse element 10. For example, first, before the third holding member 50C (corresponding to the lid member that constitutes the insulating case 50) is mounted on the second holding member 50B, the third filler 73 is placed in the internal pressure buffering space 55. Thereafter, the third holding member 50C is attached to the second holding member 50B, thereby filling the internal pressure buffering space 55 with the third filler 73.

[0113] The third filler 73 does not necessarily have to fill the internal pressure buffering space 55 completely without any gaps, but may fill the internal pressure buffering space 55 with gaps in part. For example, the third filler 73 may be disposed in at least a part of the internal pressure buffering space 55 and be in contact with the bottom surface of the recess that forms the internal pressure buffering space 55.

[0114] The orientation of the protective element 1 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 the direction of gravity. For example, if the third filler 73 is filled tightly into the internal pressure buffering space 55, even if the protective element 1 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 55. For example, the arrangement of the protective element 1 can be changed according to design specifications.

[0115] (Effects of the Present Embodiment) The protective element 1 of the present embodiment described above includes a first fuse element 10, a first terminal 30 and a second terminal 40 connected to both ends of the first fuse element 10 in the current-carrying direction, and an insulating case 50 that accommodates portions of the first terminal 30 and the second terminal 40 and the first fuse element 10. The first fuse element 10 has a first conductor 11 and a first fusible conductor 12 connected in series in the current-carrying direction. The first conductor 11 includes a first buffer portion 15 that relieves physical stress. A first buffer space 51 is formed in the insulating case 50 around the first buffer portion 15. The protective element 1 further includes a first filler 71 arranged in the first buffer space 51 so as to surround the first buffer portion 15. The insulating case 50 is configured to be in proximity to or in contact with a portion of the first fuse element 10 other than the periphery of the first buffer portion 15. This configuration narrows the space formed between the insulating case 50 and the area of ​​the first fuse element 10 other than the area around the first buffer portion 15. Additionally, the first buffer portion 15 of the first fuse element 10 is surrounded by the first filler 71. This minimizes the amount of gas, which is one of the sources of arc discharge that occurs during overcurrent interruption, around the first fuse element 10. This suppresses the generation of plasma due to ionization of the gas, which is one of the sources of arc discharge, thereby suppressing arc discharge. Furthermore, there is no need to fill the area around the first fuse element 10 with silica sand, known as an arc-extinguishing agent, to suppress arc discharge. This eliminates 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 provides a protective element 1 that suppresses arc discharge during interruption, is capable of high-voltage and high-current interruption, and suppresses a decrease in insulation resistance after interruption. In addition, physical stress is alleviated in the first buffer portion 15 of the first fuse element 10, which can mitigate expansion / contraction and deformation due to the difference in thermal expansion between the first fuse element 10 and the insulating case 50. This ensures reliability against temperature cycles of the protection element 1. This makes it possible to both suppress arc discharge and alleviate thermal expansion / contraction stress of the first fuse element 10 due to temperature cycles of the protection element 1.

[0116] In this embodiment, the first fuse element 10 further includes a second conductor 13 connected in series with the first soluble conductor 12 in the current-carrying direction. The first conductor 11 is connected to one end of the first soluble conductor 12. The second conductor 13 is connected to the other end of the first soluble conductor 12. The first terminal 30 is connected to the first conductor 11. The second terminal 40 is connected to the second conductor 13. The second conductor 13 includes a second buffer section 16 that relieves physical stress. The insulating case 50 includes a second buffer space 52 formed around the second buffer section 16. The protective element 1 further includes a second filler 72 arranged in the second buffer space 52 so as to surround the second buffer section 16. With this configuration, the second buffer section 16 of the first fuse element 10 is surrounded by the second filler 72, thereby minimizing gas, which is one of the sources of arc discharge that occurs when an overcurrent is interrupted, around the first fuse element 10. This suppresses the generation of plasma due to the ionization of gas, which is one of the sources of arc discharge, and thus the arc discharge can be suppressed. In addition, since physical stress is alleviated in each of the first buffer portion 15 and the second buffer portion 16 of the first fuse element 10, expansion / contraction and deformation due to the difference in thermal expansion between the first fuse element 10 and the insulating case 50 can be more effectively alleviated.

[0117] In this embodiment, the insulating case 50 is formed with an element accommodating space 53 in a portion other than the periphery of the first buffer portion 15 of the first fuse element 10, and an internal pressure buffering space 55 that communicates with the element accommodating space 53 via a leak hole and / or gap 54. The protective element 1 further includes a third filler 73 disposed in at least a portion of the internal pressure buffering space 55. With this configuration, the insulating case 50 can suppress the occurrence of arc discharge, while the third filler 73 can sufficiently suppress a sudden increase in the internal pressure of the protective element 1 caused by molten debris entering the internal pressure buffering space 55. Therefore, it is possible to suppress the occurrence of a large-scale arc discharge when the first fuse element 10 melts.

[0118] In this embodiment, each of the first conductor 11 and the second conductor 13 is a metal plate-like member. The insulating case 50 is configured to be in close proximity to or in contact with the front and back surfaces of the plate-like members other than the periphery of the first buffer portion 15 of the first conductor 11 and the periphery of the second buffer portion 16 of the second conductor 13. This configuration allows each of the first buffer portion 15 of the first conductor 11 and the second buffer portion 16 of the second conductor 13 to be formed by bending. For example, each of the first buffer portion 15 and the second buffer portion 16 can be easily formed by bending (pressing). In addition, arc discharge can be suppressed in the front and back surfaces of the plate-like members other than the periphery of the first buffer portion 15 of the first conductor 11 and the periphery of the second buffer portion 16 of the second conductor 13.

[0119] In this embodiment, each of the first conductor 11 and the second conductor 13 is 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 each of the first conductor 11 and the second conductor 13 is a laminate including a high-melting-point metal layer and a low-melting-point metal layer. Therefore, the first conductor 11 and the second conductor 13 made of a single layer including Ag or Cu can be made thinner even when the same electrical resistance is achieved with the same area as a laminate including a high-melting-point metal layer and a low-melting-point metal layer. When the thickness of each of the first conductor 11 and the second conductor 13 is thin, the amount of molten material that flies off when the first fuse element 10 melts is proportionally smaller, resulting in higher insulation resistance after interruption.

[0120] In this embodiment, the insulating case 50 includes a first holding member 50A having at least a first buffer space 51 formed therein, a second holding member 50B having an internal pressure buffer space 55 formed therein, a third holding member 50C that shields an open surface 56 of the internal pressure buffer space 55, and a cover 50D that is inserted from a direction perpendicular to the stacking direction of the first holding member 50A, the second holding member 50B, and the third holding member 50C. With this configuration, the first holding member 50A, the second holding member 50B, and the third holding member 50C are housed in the cover 50D in a stacked state, thereby maintaining these holding members fixed to one another. This stabilizes the posture of the first fuse element 10 and portions of the first and second terminals 30 and 40 that are disposed between the holding members.

[0121] In the present embodiment, the first filler 71 and the second filler 72 are each made of an elastic resin. With this configuration, the first buffer portion 15 and the second buffer portion 16 of the first fuse element 10 are each surrounded by elastic resin, which more effectively reduces expansion / contraction and deformation due to the difference in thermal expansion between the first fuse element 10 and the insulating case 50.

[0122] 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 1 due to molten debris entering the internal pressure buffering space 55. 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 1 due to molten debris entering the internal pressure buffering space 55.

[0123] In this embodiment, flux 75 is applied to at least one surface of the first soluble conductor 12. According to this configuration, when an overcurrent flows, the first soluble conductor 12 is easily melted, and the overcurrent interruption speed can be improved.

[0124] In this embodiment, the insulating case 50 is made of a polyamide-based resin or a fluororesin. According to this configuration, polyamide-based resins and fluororesins 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 50 from aliphatic polyamide, graphite production due to arc discharge when the first fuse element 10 melts can be suppressed, and the formation of a new current path can be more reliably prevented.

[0125] In this embodiment, an example has been given in which the first fuse element 10 includes a first fusible conductor 12 and a conductor made of different materials, but this is not limited to this. For example, the entire first fuse element 10 may be composed of Ag or Cu, or Ag or Cu as the main component. In this case, the first fuse element 10 contains Ag or Cu. The first fuse element 10 may be Cu alone, Ag alone, a Cu alloy, or an Ag alloy.

[0126] 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.

[0127] Second Embodiment A protective element 201 according to a second embodiment of the present invention will be described with reference to Fig. 6 to Fig. 9. The protective element 201 of the second embodiment differs from the first embodiment described above mainly in that it includes a heating element 80 and a power supply member 81. In each drawing 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.

[0128] 6 to 9, the protective element 201 includes a first fuse element 10, a first terminal 30 and a second terminal 40 connected to both ends of the first fuse element 10 in the current-carrying direction, a heating element 80, a power supply member 81 connected to the heating element 80, and an insulating case 250 that houses a portion of the first terminal 30 and the second terminal 40, the first fuse element 10, the heating element 80, and a portion of the power supply member 81.

[0129] The protective element 201 of this embodiment has a mechanism for interrupting the current path, which includes an overcurrent interruption mechanism in which the first fuse element 10 melts to interrupt 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 10, 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 10 and interrupting the current path.

[0130] The heating element 80 is arranged so as to overlap the first fuse element 10 in the vertical direction. The heating element 80 contacts the first fuse element 10 in the vertical direction. The heating element 80 generates heat when current is passed through the power supply member 81, and melts and blows out at least a portion of the first fuse element 10. Specifically, the heating element 80 is arranged so as to overlap the first fusible conductor 12 in the vertical direction, and is stacked in the vertical direction with the rear end of the first conductor 11 and the front end of the second conductor 13. The heating element 80 melts and blows out at least a portion of the first fusible conductor 12 due to the heat generated by the current. In the following description, "melt and blow out at least a portion" may be abbreviated to "melt and blow out".

[0131] 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 250. In other words, the heating element 80 is housed in the insulating case 250.

[0132] The heating element accommodating portion 61 is recessed from the surface of the insulating case 250 facing the first fuse element 10 of the second holding member 50B. 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 50B. The heating element accommodating portion 61 is disposed toward the center of the second holding member 50B 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 60 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 60 is smaller than the vertical dimension of the heating element accommodating portion 61.

[0133] The 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 the first fuse element 10, 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, the 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 10 in the top-to-bottom direction, an insulating layer, and a heating element electrode.

[0134] For example, 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 for the protective element 201, the heating element 80 is energized and generates heat by a current control element provided in the external circuit.

[0135] The power supply member 81 is a member that supplies power to the heating element 80. The power supply member 81 extends from the outside to the inside of the insulating case 250, 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 81 is made of an electric wire (wiring member). Note that at least a portion of the power supply member 81 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.

[0136] The insulating case 250 includes a first holding member 50A in which at least a first buffer space 51 is formed, a second holding member 50B in which an internal pressure buffer space 55 is formed, a third holding member 50C that shields an open surface 56 of the internal pressure buffer space 55, and a first cover 250D1 and a second cover 250D2 that are inserted from both directions perpendicular to the stacking direction of the first holding member 50A, the second holding member 50B, and the third holding member 50C. Note that the first buffer space 51 may be formed in the second holding member 50B instead of the first holding member 50A.

[0137] Each of the first cover 250D1 and the second cover 250D2 has a cylindrical shape extending in the front-rear direction. In the illustrated example, each of the first cover 250D1 and the second cover 250D2 has a cylindrical shape that opens in the front-rear direction. The first cover 250D1 and the second cover 250D2 have approximately the same front-rear length. The three holding members are housed within the first cover 250D1 and the second cover 250D2 in a combined state aligned vertically. The first cover 250D1 and the second cover 250D2 hold the three holding members 50A, 50B, and 50C in a fixed state by adhesive or the like. The power supply member 81 extends in the left-right direction through the gap between the first cover 250D1 and the second cover 250D2. Note that the first cover 250D1 and the second cover 250D2 may have different front-rear lengths.

[0138] In this embodiment, the leak hole and / or gap 254 is formed at a position different from the leak hole and / or gap 54 described above. In the example shown in the figure, two leak holes and / or gaps 254 are arranged at an interval in the front-to-rear direction. The leak holes and / or gaps 254 extend linearly in the up-down direction. The leak holes and / or gaps 254 extend linearly in the left-to-right direction. The leak holes and / or gaps 254 are arranged near the heating element 80. The leak holes and / or gaps 254 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 254 is larger than the left-to-right dimension of the heating element 80. For example, the opening area of ​​the leak holes and / or gaps 54, 254 (the sum of the cross-sectional areas of the leak holes and / or gaps 54, 254 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 insulating case 50 and the first fuse element 10 are close to or in contact with each other in the area where the insulating case 50 and the first fuse element 10 are close to or in contact with each other, but is not limited outside the area where the insulating case 50 and the first fuse element 10 are close to or in contact with each other. For example, the left-right dimension of the leak holes and / or gaps 254 may be equal to or less than the left-right dimension of the heating element 80. For example, the leak holes and / or gaps 54 may not be formed, and the leak holes and / or gaps 254 may be formed instead. For example, the leak holes and / or gaps 54 may be formed instead of the leak holes and / or gaps 254, or the leak holes and / or gaps 54 may be formed together with the leak holes and / or gaps 254. The configuration of the leak holes and / or gaps 54, 254 (number, location, shape, opening area, etc.) is not limited to the above and can be changed according to design specifications.

[0139] In the protective element 201 of the present embodiment described above, 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 10, the first fuse element 10 generates heat and melts, thereby interrupting the current path. Furthermore, the protective element 201 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 10 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 10 melts, and it is possible to provide a protective element 201 that can perform both an overcurrent interruption and an interruption function in response to an interruption signal.

[0140] Third Embodiment A protection element 301 according to a third embodiment of the present invention will be described with reference to Figures 10 and 11. The protection element 301 of the third embodiment differs from the first embodiment described above mainly in that it further includes a second fuse element 20 arranged in parallel with the first fuse element 10, and an insulating member 90. In each drawing 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.

[0141] 10 and 11 , the protective element 301 includes a second fuse element 20 arranged in parallel with the first fuse element 10 and connected to the first terminal 30 and the second terminal 40, an insulating member 90 arranged between the first fuse element 10 and the second fuse element 20, and an insulating case 350 that houses a portion of the first terminal 30 and the second terminal 40, the first fuse element 10, the second fuse element 20, and the insulating member 90.

[0142] The second fuse element 20 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 20 is provided, but this is not limited to this. For example, two second fuse elements 20 may be provided side by side in the vertical direction, or three or more second fuse elements 20 may be provided side by side. For example, the installation mode of the second fuse element 20 can be changed depending on the design specifications.

[0143] The second fuse element 20 has a third conductor 21, a second fusible conductor 22, and a fourth conductor 23 connected in series in the current flow direction (specifically, the current flow direction of the second fuse element 20). For example, the second fusible conductor 22 is made of a material having a lower melting temperature than each of the third conductor 21 and the fourth conductor 23. For example, the second fusible conductor 22 has a higher electrical resistivity than each of the third conductor 21 and the fourth conductor 23. The second fusible conductor 22 functions as a melting portion of the second fuse element 20 when an overcurrent is interrupted.

[0144] The second fusible conductor 22 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 22 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 22 is disposed in the center of the second fuse element 20 in the front-to-back direction. In this embodiment, flux 75 is applied to at least one surface of the second fusible conductor 22.

[0145] For example, the second soluble conductor 22 is made of Sn (tin) or a metal mainly composed of Sn. Although not shown, the second soluble conductor 22 may be a laminate including a high melting point metal layer and a low melting point metal layer. For example, the second soluble conductor 22 is formed of the same material as the first soluble conductor 12. Note that the second soluble conductor 22 is not limited to the above and may be formed of a material different from the first soluble conductor 12. For example, the material of the second soluble conductor 22 can be changed according to the design specifications.

[0146] Each of the third conductor 21 and the fourth conductor 23 has a plate, sheet, or foil shape. In this embodiment, each of the third conductor 21 and the fourth conductor 23 is a metal plate-like member. In the example shown in the figure, each of the third conductor 21 and the fourth conductor 23 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 third conductor 21 and the fourth conductor 23 is made of Ag or Cu, or a metal containing Ag or Cu as a main component.

[0147] The third conductor 21, the second fusible conductor 22, and the fourth conductor 23 are connected in series in this order to form a current path of the second fuse element 20. Each of the third conductor 21 and the fourth conductor 23 is connected to an end of the second fusible conductor 22 in the current direction in which current flows through the second fuse element 20 (approximately the front-to-back direction in the example shown in the figure).

[0148] The third conductor 21 is connected to one end of the second soluble conductor 22. In the example shown in the figure, the rear end of the third conductor 21 is fixed to the front end of the second soluble conductor 22. Specifically, the upper surface of the rear end of the third conductor 21 is connected to the lower surface of the front end of the second soluble conductor 22. The fourth conductor 23 is connected to the other end of the second soluble conductor 22. In the example shown in the figure, the front end of the fourth conductor 23 is fixed to the rear end of the second soluble conductor 22. Specifically, the upper surface of the front end of the fourth conductor 23 is connected to the lower surface of the rear end of the second soluble conductor 22. The second soluble conductor 22 is arranged on the upper surface of the third conductor 21 and the fourth conductor 23 and is stretched between them.

[0149] The first terminal 30 and the third conductor 21 are connected. In the illustrated example, the rear end of the first terminal 30 is fixed to the front end of the third conductor 21. 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 21 are connected to each other. The second terminal 40 and the fourth conductor 23 are connected. In the illustrated example, the front end of the second terminal 40 is fixed to the rear end of the fourth conductor 23. 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 23 are connected to each other.

[0150] The third conductor 21 includes an inner plate portion 21A connected to the second fusible conductor 22 and a third buffer portion 25 arranged in the first buffer space 351 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 15 and the third buffer portion 25 is arranged in the first buffer space 351 so as to be surrounded by the first filler 71.

[0151] 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 22 by soldering or the like.

[0152] The third buffer portion 25 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 25 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.

[0153] In the illustrated example, the third buffer section 25 has a curved shape that protrudes upward. In other words, the third buffer section 25 has a hat shape that protrudes upward when viewed from the left and right. The third buffer section 25 is not limited to the above shape, and may have a curved shape that protrudes downward. For example, the third buffer section 25 may have a crank shape when viewed from the left and right. For example, the shape of the third buffer section 25 can be changed according to design specifications.

[0154] The fourth conductor 23 includes an inner plate portion 23A connected to the second fusible conductor 22 and a fourth buffer portion 26 arranged in the second buffer space 352 so as to be surrounded by the second filler 72 and to relieve physical stress. In the example shown in the figure, each of the second buffer portion 16 and the fourth buffer portion 26 is arranged in the second buffer space 352 so as to be surrounded by the second filler 72.

[0155] 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 22 by soldering or the like.

[0156] The fourth buffer portion 26 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 26 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.

[0157] In the illustrated example, the fourth buffer portion 26 has a curved shape that protrudes upward. In other words, the fourth buffer portion 26 has a hat shape that protrudes upward when viewed from the left and right. The fourth buffer portion 26 is not limited to the above shape, and may have a curved shape that protrudes downward. For example, the fourth buffer portion 26 may have a crank shape when viewed from the left and right. For example, the shape of the fourth buffer portion 26 can be changed according to design specifications.

[0158] The insulating member 90 is plate-shaped, with a pair of plate surfaces facing the vertical direction. In the example shown in the figure, the insulating member 90 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 90 is made of a resin with a tracking resistance index (CTI) of 500 V or more. For example, the insulating member 90 is made of a polyamide-based resin material or a fluorine-based resin material. Examples of resin materials that make up the insulating member 90 are the same as those used for the insulating case 50 (cover 50D and each holding member) described above.

[0159] The insulating member 90 has a first opposing surface 91 that is in close proximity to or in contact with the first fuse element 10, and a second opposing surface 92 that is in close proximity to or in contact with the second fuse element 20. In the example shown in the figure, the lower surface of the insulating member 90 corresponds to the first opposing surface 91, and the upper surface of the insulating member 90 corresponds to the second opposing surface 92.

[0160] Although not shown, the insulating member 90 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) in which current flows through the fuse elements 10, 20. When the slit portion is formed in the insulating member 90, molten spatter that adheres to the first opposing surface 91 and the second opposing surface 92 of the insulating member 90 after the fuse elements 10, 20 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.

[0161] The insulating case 350 is formed with a first buffer space 351 around the first buffer section 15 and the third buffer section 25, a second buffer space 352 around the second buffer section 16 and the fourth buffer section 26, a first element accommodating space 353A in a region other than the periphery of the first buffer section 15 and the periphery of the second buffer section 16 of the first fuse element 10, a second element accommodating space 353B in a region other than the periphery of the third buffer section 25 and the periphery of the fourth buffer section 26 of the second fuse element 20, and an internal pressure buffering space 55 communicating with each of the first element accommodating space 353A and the second element accommodating space 353B via a leak hole and / or a gap 54. The insulating case 350 is configured to be in proximity to or in contact with a region other than the periphery of the first buffer section 15 and the periphery of the second buffer section 16 of the first fuse element 10, and a region other than the periphery of the third buffer section 25 and the periphery of the fourth buffer section 26 of the second fuse element 20.

[0162] The insulating case 350 comprises a first holding member 50A in which at least a first buffer space 351 is formed, a second holding member 350B in which an internal pressure buffer space 55 is formed, a third holding member 350C that shields the open surface 56 of the internal pressure buffer space 55, and a cover 50D that is inserted from a direction perpendicular to the direction in which the first holding member 50A, the second holding member 350B, and the third holding member 350C are stacked.

[0163] The first holding member 50A is disposed below the first terminal 30, the second terminal 40, and the first fuse element 10. The first holding member 50A includes a terminal mounting surface 57, a terminal locking portion 58, and a conductor-facing recess 360.

[0164] The conductor facing recess 360 of the first holding member 50A is a recessed shape recessed downward from the central portion of the upper surface of the first holding member 50A in the front-to-back direction of the first fuse element 10. The conductor facing recess 360 of the first holding member 50A is a substantially rectangular hole opening upward. The bottom surface of the conductor facing recess 360 is flat facing upward and extends in a plane direction (XY plane direction) perpendicular to the vertical direction. The bottom surface of the conductor facing recess 360 of the first holding member 50A faces the underside of the first fusible conductor 12.

[0165] The second holding member 350B is disposed above the first terminal 30, the second terminal 40, and the second fuse element 20. The upper surface of the second holding member 350B forms the open surface 56 of the internal pressure buffering space 55. The second holding member 350B includes a terminal pressing surface 59 and a conductor-facing recess 360.

[0166] The conductor facing recess 360 of the second holding member 350B is a recessed shape recessed upward from the central portion of the second fuse element 20 in the front-to-back direction of the lower surface of the second holding member 350B. The conductor facing recess 360 of the second holding member 350B is a substantially rectangular hole opening downward. The bottom surface of the conductor facing recess 360 of the second holding member 350B 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 360 of the second holding member 350B faces the upper surface of the second fusible conductor 22.

[0167] The second holding member 350B has a through-hole 365 that opens in the vertical direction. The through-hole 365 is disposed so as to overlap with each of the first buffer space 351 and the second buffer space 352 when viewed from the vertical direction.

[0168] The third holding member 350C has a protrusion 366 that protrudes downward from a portion that extends in a plane perpendicular to the up-down direction and fits into the through-hole 365. The protrusion 366 is arranged to overlap with each of the first buffer space 351 and the second buffer space 352 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 366 in the front-to-rear direction and the wall surface that forms the through-hole 365.

[0169] The three holding members 50A, 350B, and 350C are housed in the cover 50D in a combined state lined up in the vertical direction with the insulating member 90 interposed therebetween. The cover 50D holds the three holding members 50A, 350B, and 350C and the insulating member 90 in a fixed state by adhesive or the like.

[0170] When the first holding member 50A, the insulating member 90, the second holding member 350B, and the third holding member 350C are combined, a first buffer space 351 and a second buffer space 352 are formed in the area surrounded by the first holding member 50A, the insulating member 90, the second holding member 350B, and the third holding member 350C. The first buffer space 351 and the second buffer space 352 are each formed by a part of a through hole 365 formed in the second holding member 350B, and are separated by a part of a protrusion 366 protruding from the third holding member 350C.

[0171] When the above-mentioned members 50A, 90, 350B, and 350C are combined, a first element accommodating space 353A is formed between the first holding member 50A and the insulating member 90. The first fuse element 10 is accommodated in the first element accommodating space 353A. When the above-mentioned members 50A, 90, 350B, and 350C are combined, a second element accommodating space 353B is formed between the second holding member 350B and the insulating member 90. The second fuse element 20 is accommodated in the second element accommodating space 353B.

[0172] A portion of the upper surface of the first holding member 50A (a portion of the surface facing the first element accommodating space 353A) is configured to be in close proximity to or in contact with the lower surface of a portion of the first fuse element 10 other than the periphery of the first buffer portion 15 and other than the periphery of the second buffer portion 16. The first opposing surface 91, which is the lower surface of the insulating member 90, is configured to be in close proximity to or in contact with the upper surface of a portion of the first fuse element 10 other than the periphery of the first buffer portion 15 and other than the periphery of the second buffer portion 16.

[0173] A portion of the lower surface of the second holding member 350B (a portion of the surface facing the second element accommodating space 353B) is configured to be in close proximity to or in contact with the upper surface of a portion of the second fuse element 20 other than the periphery of the third buffer portion 25 and other than the periphery of the fourth buffer portion 26. The second opposing surface 92, which is the upper surface of the insulating member 90, is configured to be in close proximity to or in contact with the lower surface of a portion of the second fuse element 20 other than the periphery of the third buffer portion 25 and other than the periphery of the fourth buffer portion 26.

[0174] When the second holding member 350B and the third holding member 350C are combined together, an internal pressure buffering space 55 is formed between the second holding member 350B and the third holding member 350C. The internal pressure buffering space 55 is a substantially rectangular parallelepiped space, and communicates with each of the first element accommodating space 353A and the second element accommodating space 353B via leak holes and / or gaps 54.

[0175] In the illustrated example, the fillers 71 and 72 are filled into portions of the buffer spaces 351 and 352 (in other words, portions of the through-holes 365), respectively, with gaps. For example, first, the second holding member 350B is mounted on the first holding member 50A, and then the fillers 71 and 72 are poured into the buffer spaces 351 and 352 through the through-holes 365 before the third holding member 350C is mounted on the second holding member 350B. At this time, the amounts of the fillers 71 and 72 poured may be adjusted taking into account the volume of the protrusions 366 of the third holding member 350C. Then, the protrusions 366 are inserted into the through-holes 365, and the third holding member 350C is attached to the second holding member 350B. This allows the fillers 71 and 72 to fill portions of the buffer spaces 351 and 352 (in other words, portions of the through-holes 365), respectively, with gaps.

[0176] The fillers 71 and 72 are not limited to being filled with gaps in portions of the buffer spaces 351 and 352, respectively, but may be filled completely without gaps in the buffer spaces 351 and 352, respectively. For example, the fillers 71 and 72 may be disposed in at least portions of the buffer spaces 351 and 352, respectively, so as to surround at least the buffer sections 15, 16, 25, and 26.

[0177] In the protective element 301 of the present embodiment described above, the first buffer portion 15 of the first fuse element 10 and the third buffer portion 25 of the second fuse element 20 are surrounded by the first filler 71, and the second buffer portion 16 of the first fuse element 10 and the fourth buffer portion 26 of the second fuse element 20 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 10 and the second fuse element 20. This suppresses plasma 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 15 and the second buffer portion 16 of the first fuse element 10 and the third buffer portion 25 and the fourth buffer portion 26 of the second fuse element 20. This more effectively alleviates expansion / contraction and deformation due to differences in thermal expansion among the first fuse element 10, the second fuse element 20, the insulating member 90, and the insulating case 350.

[0178] Fourth Embodiment A protective element 401 according to a fourth embodiment of the present invention will be described with reference to Fig. 12. The protective element 401 of the fourth embodiment differs from the third embodiment described above mainly in that it includes a heating element 80 and a power supply member 81. In each drawing of this embodiment, components that are the same or substantially the same as those in the first to third embodiments described above may be denoted by the same reference numerals or names, and descriptions thereof may be omitted.

[0179] 12, the protective element 401 includes a first fuse element 10, a first terminal 30 and a second terminal 40 connected to both ends of the first fuse element 10 in the current-carrying direction, a heating element 80, a power supply member 81 (not shown in FIG. 12) connected to the heating element 80, a second fuse element 20 arranged in parallel with the first fuse element 10 and connected to the first terminal 30 and the second terminal 40, an insulating member 90 arranged between the first fuse element 10 and the second fuse element 20, and an insulating case 450 that houses a portion of the first terminal 30 and the second terminal 40, the first fuse element 10 and the second fuse element 20, the heating element 80, a portion of the power supply member 81, and the insulating member 90.

[0180] The protective element 401 of this embodiment has a mechanism for interrupting the current path, which includes an overcurrent interruption mechanism in which the fuse elements 10 and 20 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 10 and 20, 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 10 and 20 and interrupting the current path.

[0181] In this embodiment, the portions to which the soluble conductors 12 and 22 are connected in each fuse element 10 and 20 are opposite to those in the third embodiment. Specifically, in the first fuse element 10, the upper surface of the rear end of the first conductor 11 is connected to the lower surface of the front end of the first soluble conductor 12, and the upper surface of the front end of the second conductor 13 is connected to the lower surface of the rear end of the first soluble conductor 12. On the other hand, in the second fuse element 20, the lower surface of the rear end of the third conductor 21 is connected to the upper surface of the front end of the second soluble conductor 22, and the lower surface of the front end of the fourth conductor 23 is connected to the upper surface of the rear end of the second soluble conductor 22.

[0182] In the example shown in the figure, a pair of conductor-facing recesses 460 are formed in the insulating member 90 in the vertical direction. Of the pair of conductor-facing recesses 460, the first soluble conductor 12 is arranged in the lower portion, and the second soluble conductor 22 is arranged in the upper portion. Of the pair of conductor-facing recesses 460, the lower portion is a concave recessed upward from the central portion of the lower surface of the insulating member 90 in the front-to-back direction, and the upper portion is a concave recessed downward from the central portion of the upper surface of the insulating member 90 in the front-to-back direction. Of the pair of conductor-facing recesses 460, the bottom surface of the lower portion faces the upper surface of the first soluble conductor 12, and the bottom surface of the upper portion faces the lower surface of the second soluble conductor 22. The pair of conductor-facing recesses 460 are arranged on the central side of the insulating member 90 in the front-to-back direction.

[0183] 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 10, 20 in the vertical direction. The lower of the pair of heating elements 80 is in contact with the first fuse element 10 in the vertical direction, and the upper of the pair of heating elements 80 is in contact with the second fuse element 20 in the vertical direction. The heating elements 80 generate heat when current is passed through the power supply member 81, melting and blowing at least a portion of each fuse element 10, 20. Specifically, the lower of the pair of heating elements 80 is arranged so as to overlap the first soluble conductor 12 in the vertical direction and is stacked in the vertical direction with the rear end of the first conductor 11 and the front end of the second conductor 13, while the upper is arranged so as to overlap the second soluble conductor 22 in the vertical direction and is stacked in the vertical direction with the rear end of the third conductor 21 and the front end of the fourth conductor 23. The pair of heating elements 80 melt and blow at least a portion of each soluble conductor 12, 22 by heat generated by current.

[0184] In the example shown in the figure, the lower of the pair of heating elements 80 is disposed in a heating element housing portion 461 formed in the first holding member 50A, and the upper of the pair of heating elements 80 is disposed in a heating element housing portion 461 formed in the second holding member 350B. In other words, the pair of heating elements 80 are housed in the insulating case 450.

[0185] In the protective element 401 of the present embodiment described above, when an overcurrent exceeding the rated current (i.e., a current equal to or greater than a predetermined value) flows through the fuse elements 10, 20, the fuse elements 10, 20 generate heat and melt, thereby interrupting the current path. Furthermore, the protective element 401 can interrupt the current path by passing a current through the heating element 80 to generate heat, thereby melting and blowing the fuse elements 10, 20 stacked on the heating element 80. According to this embodiment, it is possible to prevent a large-scale arc discharge from occurring when the fuse elements 10, 20 melt, and it is possible to provide a protective element 401 that can achieve both an overcurrent cutoff function and a cutoff function in response to a cutoff signal.

[0186] 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.

[0187] 1, 201, 301, 401 Protection element 10 First fuse element 11 First conductor 12 First fusible conductor 13 Second conductor 15 First buffer portion 16 Second buffer portion 20 Second fuse element 21 Third conductor 22 Second fusible conductor 23 Fourth conductor 25 Third buffer portion 26 Fourth buffer portion 30 First terminal 40 Second terminal 50, 250, 350, 450 Insulating case 50A First holding member 50B Second holding member 50C Third holding member 50D Cover 51, 351 First buffer space 52, 352 Second buffer space 53 Element accommodating space 54 Leak hole and / or gap 55 Internal pressure buffer space 56 Open surface 71 First filler 72 Second filler 73 Third filler 75 Flux 80 Heating element 81 Power supply member 90 Insulating member 91 First opposing surface 92 Second opposing surface 250D1 First cover 250D2 Second cover 254 Leak hole and / or gap 350B Second holding member 350C Third holding member 353A First element accommodating space 353B Second element accommodating space

Claims

1. A protective element comprising: a first fuse element; a first terminal and a second terminal connected to both ends of the first fuse element in a current flow direction; and an insulating case that accommodates a portion of the first terminal and the second terminal and the first fuse element, wherein the first fuse element has a first conductor and a first fusible conductor connected in series in the current flow direction of the first fuse element, the first conductor having a first buffer portion that relieves physical stress, a first buffer space is formed around the first buffer portion in the insulating case, and the insulating case is further configured to be in close proximity to or in contact with a portion of the first fuse element other than the periphery of the first buffer portion.

2. The protective element described in claim 1, wherein the first fuse element further has a second conductor connected in series with the first soluble conductor in the direction of current flow of the first fuse element, the first conductor is connected to one end of the first soluble conductor, the second conductor is connected to the other end of the first soluble conductor, the first terminal is connected to the first conductor, and the second terminal is connected to the second 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 protective element further comprises a second filler arranged in the second buffer space to surround the second buffer section.

3. A protective element as described in claim 1 or 2, wherein the insulating case is formed with an element accommodating space in a portion other than the periphery of the first buffer portion of the first fuse element, and an internal pressure buffering space communicating with the element accommodating space via a leak hole and / or a gap, and further comprising a third filler disposed in at least a portion of the internal pressure buffering space.

4. A protective element as described in claim 2, wherein each of the first conductor and the second conductor is a metal plate-like member, and the insulating case is configured to be in close proximity to or in contact with a front surface portion and a back surface portion of the plate other than the periphery of the first buffer portion of the first conductor and other than the periphery of the second buffer portion of the second conductor.

5. The protective element according to claim 2 or 4, 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.

6. The protective element according to claim 1 or 2, wherein the first fusible conductor is made of Sn or a metal containing Sn as a main component.

7. The protective element according to claim 1 or 2, wherein the first fusible conductor is a laminate including a high melting point metal layer and a low melting point metal layer.

8. The protective element according to claim 7, wherein the high melting point metal layer is made of Ag or Cu, or a metal mainly composed of Ag or Cu, and the low melting point metal layer is made of Sn or a metal mainly composed of Sn.

9. A protective element as described in claim 3, wherein the insulating case comprises: a first retaining member in which at least the first buffer space is formed; a second retaining member in which the internal pressure buffer space is formed; a third retaining member that shields an open face of the internal pressure buffer space; and a cover that is inserted from a direction perpendicular to the direction in which the first retaining member, the second retaining member, and the third retaining member are stacked.

10. The protective element according to claim 2, wherein each of the first filling material and the second filling material is made of an elastic resin.

11. The protection element according to claim 10, wherein the elastic resin is a silicone resin or a photocurable acrylic resin.

12. The protective element according to claim 3, wherein the third filler includes at least insulating fiber or silica sand.

13. The protection element according to claim 12, wherein the insulating fiber is a ceramic fiber paper.

14. The protective element according to claim 1 or 2, wherein flux is applied to at least one surface of the first fusible conductor.

15. The protective element according to claim 1 or 2, wherein the insulating case is made of a polyamide resin or a fluorine resin.

16. A protective element comprising: a first fuse element; a first terminal and a second terminal connected to both ends of the first fuse element in a current flow direction; a heating element; a power supply member connected to the heating element; and an insulating case that accommodates a portion of the first terminal and the second terminal, the first fuse element, the heating element, and a portion of the power supply member, wherein the first fuse element has a first conductor and a first fusible conductor connected in series in the current flow direction of the first fuse element, the first conductor having a first buffer portion that relieves physical stress, a first buffer space is formed around the first buffer portion in the insulating case, and the insulating case is further configured to be in close proximity to or in contact with a portion of the first fuse element other than the periphery of the first buffer portion.

17. The protective element described in claim 16, wherein the first fuse element further has a second conductor connected in series with the first fusible conductor in the direction of current flow of the first fuse element, the first conductor is connected to one end of the first fusible conductor, the second conductor is connected to the other end of the first fusible conductor, the first terminal is connected to the first conductor, and the second terminal is connected to the second 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 protective element further comprises a second filler arranged in the second buffer space to surround the second buffer section.

18. A protective element as described in claim 16 or 17, wherein the insulating case is formed with an element accommodating space in a portion other than the periphery of the first buffer portion of the first fuse element, and an internal pressure buffering space communicating with the element accommodating space via a leak hole and / or a gap, and further comprising a third filler material disposed in at least a portion of the internal pressure buffering space.

19. A protective element as described in claim 17, wherein each of the first conductor and the second conductor is a metal plate-like member, and the insulating case is configured to be in close proximity to or in contact with a front surface portion and a back surface portion of the plate other than the periphery of the first buffer portion of the first conductor and other than the periphery of the second buffer portion of the second conductor.

20. A protective element according to claim 17 or 19, 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.

21. The protective element according to claim 16 or 17, wherein the first fusible conductor is made of Sn or a metal containing Sn as a main component.

22. The protective element according to claim 16 or 17, wherein the first fusible conductor is a laminate including a high melting point metal layer and a low melting point metal layer.

23. The protective element according to claim 22, wherein the high melting point metal layer is made of Ag or Cu, or a metal mainly composed of Ag or Cu, and the low melting point metal layer is made of Sn or a metal mainly composed of Sn.

24. A protective element as described in claim 18, wherein the insulating case comprises: a first retaining member in which at least the first buffer space is formed; a second retaining member in which the internal pressure buffer space is formed; a third retaining member that shields the open face of the internal pressure buffer space; and a first cover and a second cover that are inserted respectively from both directions perpendicular to the direction in which the first retaining member, the second retaining member, and the third retaining member are stacked.

25. The protection element according to claim 17, wherein each of the first filling material and the second filling material is made of an elastic resin.

26. The protection element according to claim 25, wherein the elastic resin is a silicone resin or a photocurable acrylic resin.

27. The protective element according to claim 18, wherein the third filler includes at least an insulating fiber or silica sand.

28. The protection element according to claim 27, wherein the insulating fiber is a ceramic fiber paper.

29. The protective element according to claim 16 or 17, wherein flux is applied to at least one surface of the first fusible conductor.

30. The protective element according to claim 16 or 17, wherein the insulating case is made of a polyamide resin or a fluorine resin.

31. A protective element as described in claim 1, comprising: a second fuse element arranged in parallel with the first fuse element and connected to the first terminal and the second terminal; and an insulating member arranged between the first fuse element and the second fuse element, the insulating member having a first opposing surface in close proximity to or in contact with the first fuse element and a second opposing surface in close proximity to or in contact with the second fuse element, the second fuse element having a third conductor and a second fusible conductor connected in series in the current flow direction of the second fuse element, the third conductor being arranged in the first buffer space so as to be surrounded by the first filler and comprising a third buffer portion that relieves physical stress, and the insulating case being configured to be in close proximity to or in contact with a portion of the second fuse element other than the periphery of the third buffer portion.

32. The protective element described in claim 31, wherein the first fuse element further has a second conductor connected in series with the first fusible conductor in the direction of current flow of the first fuse element, the first conductor is connected to one end of the first fusible conductor, the second conductor is connected to the other end of the first fusible conductor, the first terminal is connected to the first conductor, and the second terminal is connected to the second conductor, the second conductor has a second buffer section that relieves physical stress, a second buffer space is formed in the insulating case around the second buffer section, and the protective element further comprises a second filler arranged in the second buffer space to surround the second buffer section.

33. The protective element described in claim 32, wherein the second fuse element further has a fourth conductor connected in series with the second fusible conductor in the current flow direction of the second fuse element, the third conductor is connected to one end of the second fusible conductor, the fourth conductor is connected to the other end of the second fusible conductor, the first terminal is connected to the third conductor, and the second terminal is connected to the fourth conductor, the fourth conductor is disposed in the second buffer space so as to be surrounded by the second filler, and is provided with a fourth buffer portion that relieves physical stress.

34. A protective element as claimed in any one of claims 31 to 33, wherein the insulating case is formed with a first element accommodating space in a portion other than the periphery of the first buffer portion of the first fuse element, and an internal pressure buffering space communicating with the first element accommodating space via a leak hole and / or a gap, and further comprising a third filler material disposed in at least a portion of the internal pressure buffering space.

35. A protective element as described in claim 34, wherein a second element accommodating space is formed in the insulating case in a portion other than the periphery of the third buffer portion of the second fuse element, and the second element accommodating space communicates with the internal pressure buffering space via the leak hole and / or gap.

36. A protective element as described in claim 16, comprising: a second fuse element arranged in parallel with the first fuse element and connected to the first terminal and the second terminal; and an insulating member arranged between the first fuse element and the second fuse element, the insulating member having a first opposing surface in close proximity to or in contact with the first fuse element and a second opposing surface in close proximity to or in contact with the second fuse element, the second fuse element having a third conductor and a second fusible conductor connected in series in the current flow direction of the second fuse element, the third conductor being arranged in the first buffer space so as to be surrounded by the first filler and comprising a third buffer portion that relieves physical stress, and the insulating case being configured to be in close proximity to or in contact with a portion of the second fuse element other than the periphery of the third buffer portion.

37. The protective element described in claim 36, wherein the first fuse element further has a second conductor connected in series with the first fusible conductor in the direction of current flow of the first fuse element, the first conductor is connected to one end of the first fusible conductor, the second conductor is connected to the other end of the first fusible conductor, the first terminal is connected to the first conductor, and the second terminal is connected to the second conductor, the second conductor has a second buffer section that relieves physical stress, a second buffer space is formed in the insulating case around the second buffer section, and the protective element further comprises a second filler arranged in the second buffer space to surround the second buffer section.

38. The protective element described in claim 37, wherein the second fuse element further has a fourth conductor connected in series with the second fusible conductor in the current flow direction of the second fuse element, the third conductor is connected to one end of the second fusible conductor, the fourth conductor is connected to the other end of the second fusible conductor, the first terminal is connected to the third conductor, and the second terminal is connected to the fourth conductor, the fourth conductor is disposed in the second buffer space so as to be surrounded by the second filler, and is provided with a fourth buffer portion that relieves physical stress.

39. A protective element as claimed in any one of claims 36 to 38, wherein the insulating case is formed with a first element accommodating space in a portion other than the periphery of the first buffer portion of the first fuse element, and an internal pressure buffering space communicating with the first element accommodating space via a leak hole and / or a gap, and further comprising a third filler material disposed in at least a portion of the internal pressure buffering space.

40. A protective element as described in claim 39, wherein a second element accommodating space is formed in the insulating case in a portion other than the periphery of the third buffer portion of the second fuse element, and the second element accommodating space communicates with the internal pressure buffering space via the leak hole and / or gap.

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