Protection Elements

Abstract

To provide a protection element in which large-scale arc discharge is hard to occur when a fuse element is fused, and an insulation case therefore can be made small-sized and lightweight.SOLUTION: A protection element is provided, comprising a fuse element laminate, an insulation case in which the fuse element laminate is housed, a first terminal and a second terminal. The fuse element laminate includes a plurality of soluble conductor sheets disposed in parallel in a thickness direction and a first insulation member disposed between the plurality of soluble conductor sheets in a proximate or contacted state. Each of the plurality of soluble conductor sheets includes a first end and a second end which are opposed to each other. One end of the first terminal is connected to the first end and the other end is exposed from the insulation case to the outside. One end of the second terminal is connected to the second end and the other end is exposed from the insulation case to the outside.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, there are fuse elements that generate heat and melt to cut off the 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, Patent Document 1 describes a fuse element used primarily in automotive electrical circuits, etc., which includes two elements connected between terminals located at both ends and a fusing portion provided approximately in the center of the elements. Patent Document 1 also describes a fuse in which a pair of fuse elements is stored inside a casing, and an arc-extinguishing material is enclosed between the fuse elements and the casing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-004634 Summary of the Invention [Problem to be solved by the invention]

[0005] In protective devices installed in high-voltage, high-current current paths, arc discharges are likely to occur when fuse elements melt. A large-scale arc discharge can destroy the insulating case housing the fuse element. For this reason, fuse elements are typically made of low-resistance, high-melting-point metals, such as copper, to suppress arc discharges. Furthermore, insulating cases are typically made of robust, heat-resistant materials, such as ceramics, and are typically enlarged in size.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a protection element that is less likely to generate a large-scale arc discharge when the fuse element melts, and that allows the size and weight of the insulating case to be reduced. [Means for solving the problem]

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

[0008] [1] A protective element having a fuse element laminate, an insulating case that houses the fuse element laminate, a first terminal, and a second terminal, wherein the fuse element laminate includes a plurality of fusible conductive sheets arranged in parallel in the thickness direction, and a first insulating member arranged between each of the plurality of fusible conductive sheets in close proximity to or in contact with each other, wherein each of the plurality of fusible conductive sheets has a first end and a second end that face each other, one end of the first terminal is connected to the first end and the other end is exposed to the outside from the insulating case, and one end of the second terminal is connected to the second end and the other end is exposed to the outside from the insulating case.

[0009] [2] A protective element according to [1], wherein a second insulating member is disposed between the lowermost soluble conductive sheet among the plurality of soluble conductive sheets and the insulating case, and between the uppermost soluble conductive sheet among the plurality of soluble conductive sheets and the insulating case. [3] The protective element described in [2], wherein the first insulating member and the second insulating member are separated so as to block the direction from the first end toward the second end at the center between the first end and the second end of the fusible conductive sheet. [4] The protection element according to [2] or [3], which has a pressing member disposed inside the insulating case and pressing the second insulating member toward the soluble conductive sheet side.

[0010] [5] The protection element according to any one of [2] to [4], wherein at least one of the first insulating member, the second insulating member, and the insulating case is formed from a material having a tracking resistance index CTI of 500 V or more. [6] The protection element according to any one of [2] to [5], wherein at least one of the first insulating member, the second insulating member, and the insulating case is formed from a resin material selected from the group consisting of polyamide resins and fluorine-based resins. [7] A protective element described in any one of [1] to [6], wherein each of the plurality of fusible conductive sheets is a laminate including a low-melting point metal layer and a high-melting point metal layer, the low-melting point metal layer including tin, and the high-melting point metal layer including silver or copper. [8] The protective element described in [7], wherein each of the plurality of fusible conductive sheets has two or more high-melting point metal layers and one or more low-melting point metal layers, and the low-melting point metal layers are arranged between the high-melting point metal layers. [9] The protection element according to any one of [1] to [6], wherein each of the plurality of soluble conductive sheets is a single layer containing silver or copper.

[0011]

[10] A protection element described in any of [1] to [9], wherein each of the plurality of fusible conductive sheets has a fusing portion between the first end and the second end, and the cross-sectional area of ​​the fusing portion in the current flow direction is smaller than the cross-sectional area of ​​the first end and the second end in the current flow direction from the first end to the second end. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a protection element that is less likely to generate a large-scale arc discharge when the fuse element melts, and that allows the size and weight of the insulating case to be reduced. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view of a protection element according to one embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the protection element shown in FIG. [Figure 3] FIG. 3 is an exploded perspective view of the fuse element laminate shown in FIG. [Figure 4] FIG. 4 is a plan view of the fusible conductive sheet shown in FIG. [Figure 5] FIG. 5 is a cross-sectional view of the protection element taken along line VV' in FIG. [Figure 6] FIG. 6 is a vertical cross-sectional view of the protection element taken along line VI-VI' in FIG. [Figure 7] 7 is a vertical cross-sectional view showing a state in which the fuse element laminate of the protection element shown in FIG. 1 has been blown. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for the sake of clarity, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate modifications can be made within the scope of the effects of the present invention.

[0015] (protective element) 1 to 6 are schematic diagrams showing a protection element according to one embodiment of the present invention. In the drawings used in the following description, the direction indicated by X is the current-carrying direction of the fuse element. The direction indicated by Y is a direction perpendicular to the X direction and is also referred to as the width direction. The direction indicated by Z is a direction perpendicular to the X direction and the Y direction and is also referred to as the thickness direction.

[0016] Fig. 1 is a perspective view of a protective element according to one embodiment of the present invention. Fig. 2 is an exploded perspective view of the protective element shown in Fig. 1. Fig. 3 is an exploded perspective view of the fuse element laminate shown in Fig. 2. Fig. 4 is a plan view of the fusible conductive sheet shown in Fig. 3. Fig. 5 is a horizontal cross-sectional view of the protective element taken along line V-V' in Fig. 1. Fig. 6 is a vertical cross-sectional view of the protective element taken along line VI-VI' in Fig. 1.

[0017] 1 to 6 includes an insulating case 10, a fuse element laminate 40 housed in the insulating case 10, a first pressing member 71, a second pressing member 72, a first terminal 91, and a second terminal 92. In the protective element 100 of this embodiment, the current flow direction refers to the direction in which electricity flows during use (X direction), and the cross-sectional area in the current flow direction refers to the area of ​​a plane perpendicular to the current flow direction (YZ plane).

[0018] (insulating case) The insulating case 10 has a substantially cylindrical shape and is made up of a cover 20 and a holding member 30. The cover 20 has a cylindrical shape with both ends open. The inner edge of the opening of the cover 20 is chamfered to form an inclined surface 21. The center of the cover 20 is a storage section 22 in which the holding member 30 is stored.

[0019] The holding member 30 is composed of a first holding member 30a and a second holding member 30b. The first holding member 30a and the second holding member 30b have the same shape and are approximately semi-cylindrical. Terminal mounting surfaces 32 are provided on the top surfaces of both ends (first end 31a, second end 31b) of the first holding member 30a and the second holding member 30b in the current-carrying direction (X direction), and semi-circular terminal adhesive injection ports 33 are provided connected to the terminal mounting surfaces 32. In addition, notches 34a are formed on both ends of the first end 31a and the second end 31b in the width direction (Y direction). By integrating the first holding member 30a and the second holding member 30b, the notches 34a form hollow case adhesive injection ports 34 that have a semi-circular groove-like cross section when viewed in the current-carrying direction. Furthermore, a convex portion 35 is provided on the top surface of the first end portion 31a, and a concave portion 36 is provided on the top surface of the second end portion 31b. The holding member 30 is formed by engaging the convex portion 35 of the first holding member 30a with the concave portion 36 of the second holding member 30b, and by engaging the concave portion 36 of the first holding member 30a with the convex portion 35 of the second holding member 30b.

[0020] The center of the first holding member 30a and the second holding member 30b in the current-carrying direction is a fuse element accommodating portion 37. The fuse element accommodating portion 37 has guide pin insertion holes 38 that receive guide pins 41 that fix the fuse element stack 40, and pressing member insertion holes 39 that receive pressing members (first pressing member 71, second pressing member 72) that press the fuse element stack 40.

[0021] The side surface of the fuse element accommodating portion 37 is scraped away, thereby forming an internal pressure buffering space 80 inside the insulating case 10. The internal pressure buffering space 80 has the effect of suppressing a sudden rise in the internal pressure of the protection element 100 caused by gas generated by arc discharge that occurs when the fuse element stack 40 melts.

[0022] The cover 20 and the holding member 30 are preferably made of a material having a CTI (resistance to tracking (carbonized conductive path) breakdown) of 500 V or more. The CTI can be determined by a test based on IEC60112.

[0023] A resin material can be used as the material for the cover 20 and the holding member 30. A resin material has a smaller heat capacity and a lower melting point than a ceramic material. For this reason, using a resin material for the holding member 30 is preferable because when gasified metal and molten and scattered metal particles adhere to the holding member 30, the surface of the holding member 30 may deform or the metal particles may aggregate into granular particles on the surface of the holding member 30, making the metal and metal particles adhered to the holding member 30 sparse and making it difficult to form a conductive path.

[0024] Examples of the resin material include polyamide-based resins and fluororesins. The polyamide-based resins may be aliphatic polyamides or semi-aromatic polyamides. Examples of aliphatic polyamides include nylon 4, nylon 6, nylon 46, and nylon 66. Examples of semi-aromatic polyamides include nylon 6T, nylon 9T, and polyphthalamide (PPA) resins. Examples of fluororesins include polytetrafluoroethylene. Furthermore, polyamide-based resins and fluororesins are highly heat-resistant and flammable. In particular, aliphatic polyamides are less likely to produce graphite when burned. Therefore, forming the cover 20 and the retaining member 30 using aliphatic polyamides more reliably prevents the formation of a new current path due to graphite generated during arc discharge when the fuse element laminate 40 melts.

[0025] (Fuse element laminate) The fuse element laminate 40 has six soluble conductive sheets 50a, 50b, 50c, 50d, 50e, and 50f arranged in parallel in the thickness direction (Z direction). First insulating members 61a, 61b, 61c, 61d, and 61e are arranged between the soluble conductive sheets 50a to 50f. The first insulating members 61a to 61e are arranged in close proximity to or in contact with the soluble conductive sheets 50a to 50f. The close proximity state is preferably such that the distance between the first insulating members 61a to 61e and the soluble conductive sheets 50a to 50f is 0.5 mm or less, and more preferably 0.2 mm or less. Furthermore, a second insulating member 62a is arranged in close proximity to or in contact with the soluble conductive sheet 50a between the lowermost soluble conductive sheet 50a of the soluble conductive sheets 50a to 50f and the first holding member 30a. Furthermore, a second insulating member 62b is disposed between the uppermost soluble conductive sheet 50f among the soluble conductive sheets 50a-50f and the second holding member 30b, in proximity to or in contact with the soluble conductive sheet 50f. The width (length in the Y direction) of the soluble conductive sheets 50a-50f is narrower than the widths of the first insulating members 61a-61e and the second insulating members 62a, 62b. By disposing the first insulating members 61a-61e and the second insulating members 62a, 62b in proximity to or in contact with each of the soluble conductive sheets 50a-50f, the space itself in which an arc discharge occurs when the soluble conductive sheets 50a-50f melts due to an overcurrent can be made extremely narrow. Because the plasma that constitutes the arc discharge is generated by ionizing gas within the space, making the space in which the arc discharge occurs extremely narrow reduces the amount of plasma generated and keeps the scale of the arc discharge small.

[0026] Each of the soluble conductive sheets 50a to 50f has a first end 51 and a second end 52 facing each other. Of the soluble conductive sheets 50a to 50f arranged in parallel in the thickness direction, the first end 51 of the bottom three soluble conductive sheets 50a to 50c is connected to the lower surface of the first terminal 91, and the first end 51 of the top three soluble conductive sheets 50d to 50f is connected to the upper surface of the first terminal 91. Furthermore, the second end 52 of the bottom three soluble conductive sheets 50a to 50c of the soluble conductive sheets 50a to 50f is connected to the lower surface of the second terminal 92, and the second end 52 of the top three soluble conductive sheets 50d to 50f is connected to the upper surface of the second terminal 92. Note that the connection positions of the soluble conductive sheets 50a to 50f to the first terminal 91 and the second terminal 92 are not limited to this. For example, all of the first ends 51 of the soluble conductive sheets 50a to 50f may be connected to the upper surface of the first terminal 91 or may be connected to the lower surface of the first terminal 91. Furthermore, all of the second ends 52 of the soluble conductive sheets 50a to 50f may be connected to the upper surface of the second terminal 92 or may be connected to the lower surface of the second terminal 92.

[0027] Each of the soluble conductive sheets 50a to 50f may be a laminate including a low melting point metal layer and a high melting point metal layer, or may be a single layer. The low-melting-point metal layer of the laminate contains Sn. The low-melting-point metal layer may be Sn alone or an Sn alloy. An Sn alloy is an alloy containing Sn as a main component. An Sn alloy is an alloy containing the highest Sn content among the metals contained in the alloy. Examples of Sn alloys include an Sn-Bi alloy, an In-Sn alloy, and an Sn-Ag-Cu alloy. The high-melting-point metal layer contains Ag or Cu. The high-melting-point metal layer may be Ag alone, Cu alone, an Ag alloy, or a Cu alloy. An Ag alloy is an alloy containing the highest Ag content among the metals contained in the alloy, and a Cu alloy is an alloy containing the highest Cu content among the metals contained in the alloy. The laminate may have a two-layer structure of a low-melting-point metal layer / a high-melting-point metal layer, or a multilayer structure of three or more layers having two or more high-melting-point metal layers and one or more low-melting-point metal layers, with the low-melting-point metal layers interposed between the high-melting-point metal layers.

[0028] In the case of a single layer, it contains Ag or Cu. The single layer may be Ag alone, Cu alone, an Ag alloy, or a Cu alloy.

[0029] Each of the soluble conductive sheets 50a to 50f may have a through hole 54 in a central portion 53 between the first end portion 51 and the second end portion 52. By having the through hole 54, the cross-sectional area of ​​the central portion 53 becomes smaller than the cross-sectional areas of the first end portion 51 and the second end portion 52. When a large current exceeding the rated current flows through each of the soluble conductive sheets 50a to 50f, the cross-sectional area of ​​the central portion 53 becomes smaller, and therefore the amount of heat generated in the central portion 53 increases, making the central portion 53 more likely to become a fusion portion and melt (disappear).

[0030] The soluble conductive sheets 50a to 50f preferably have the same cross-sectional area in the X direction (current flow direction). The cross-sectional areas of the soluble conductive sheets 50a to 50f may be within ±10% of the average cross-sectional area of ​​the soluble conductive sheets 50a to 50f. The thickness of the soluble conductive sheets 50a to 50f is not particularly limited, but can be, for example, within the range of 0.01 mm to 1.0 mm. When the soluble conductive sheets 50a to 50f are single-layered bodies containing Ag or Cu, the thickness is preferably 0.01 mm to 0.1 mm, and when the soluble conductive sheets 50a to 50f are laminated bodies containing a low-melting-point metal layer and a high-melting-point metal layer, the thickness is preferably 0.1 mm to 0.5 mm.

[0031] Each of the first insulating members 61a to 61e and the second insulating members 62a, 62b is composed of a first insulating piece 63a and a second insulating piece 63b that face each other with a gap 65 between them. The first insulating piece 63a and the second insulating piece 63b each have a guide pin through-hole 64 into which the guide pin 41 is inserted. The gap 65 is located at a position facing the center portion 53 between the first end portion 51 and the second end portion 52 of each of the soluble conductive sheets 50a to 50f. In other words, each of the first insulating members 61a to 61e and the second insulating members 62a, 62b is separated at a position facing the center portion 53 between the first end portion 51 and the second end portion 52 of each of the soluble conductive sheets 50a to 50f.

[0032] The first insulating members 61a to 61e and the second insulating members 62a and 62b are preferably made of a material with a tracking resistance index CTI of 500V or more. The first insulating members 61a to 61e and the second insulating members 62a and 62b may be made of a resin material, which is the same as the resin material used for the cover 20 and the holding member 30.

[0033] The guide pin 41 may be, for example, an insulating wire such as a resin wire or a glass wire. The resin wire may be made of, for example, a polyamide resin, a polyethylene resin, a polypropylene resin, or a polycarbonate resin. The diameter of the guide pin 41 may be, for example, within a range of 0.5 mm to 1.2 mm. The guide pin 41 may be, for example, a nylon wire.

[0034] The fuse element laminate 40 can be manufactured, for example, as follows. First, the guide pins 41 are inserted into the guide pin insertion holes 38 of the first holding member 30a. Next, the soluble conductive sheets 50a-50f and the first insulating members 61a-61e are alternately stacked in the thickness direction on the second insulating member 62a while inserting the guide pins 41 into the guide pin through holes 64 of the first insulating members 61a-61e and the second insulating members 62a, 62b, respectively, and the second insulating member 62b is placed on the top surface of the soluble conductive sheet 50f to obtain a laminate. Instead of the first holding member 30a with the guide pins 41 inserted, a metal jig of the same shape or one with the guide pins 41 erected in appropriate positions may be used.

[0035] (First pressing member, second pressing member) One end of the first pressing member 71 is inserted into the pressing member insertion hole 39 of the first holding member 30a, and the other end is in contact with the end of the second insulating piece 63b of the second insulating member 62a on the gap 65 side. The first pressing member 71 presses the second insulating piece 63b upward (toward the soluble conductive sheet 50a). The pressure of the first pressing member 71 is, for example, a pressure that does not cut the soluble conductive sheets 50a-50f, but is a pressure that is able to press upward the first insulating members 61a-61e and the second insulating pieces 63b of the second insulating members 62a, 62b when the soluble conductive sheets 50a-50f melt.

[0036] One end of the second pressing member 72 is inserted into the pressing member insertion hole 39 of the second holding member 30b, and the other end is in contact with the end of the first insulating piece 63a of the second insulating member 62b on the gap 65 side. The second pressing member 72 presses the first insulating piece 63a downward (toward the soluble conductive sheet 50f). The pressure of the second pressing member 72 is, for example, a pressure that does not cut the soluble conductive sheets 50a-50f, but is a pressure that can press downward the first insulating members 61a-61e and the first insulating pieces 63a of the second insulating members 62a, 62b when the soluble conductive sheets 50a-50f melt.

[0037] The first pressing member 71 and the second pressing member 72 may be made of, for example, a compression coil spring and rubber.

[0038] (1st terminal, 2nd terminal) The first terminal 91 has one end connected to the first end 51 of the soluble conductive sheets 50a to 50f, and the other end exposed to the outside of the insulating case 10. The second terminal 92 has one end connected to the second end 52 of the soluble conductive sheets 50a to 50f, and the other end exposed to the outside of the insulating case 10.

[0039] The first terminal 91 and the second terminal 92 may have substantially the same shape or different shapes. The thickness of the first terminal 91 and the second terminal 92 is not particularly limited, but may be, for example, within the range of 0.3 mm to 1.0 mm. The thickness of the first terminal 91 and the thickness of the second terminal 92 may be the same or different.

[0040] The first terminal 91 has an external terminal hole 91a. The second terminal 92 has an external terminal hole 92a. One of the external terminal hole 91a and the external terminal hole 92a is used for connection to the power supply side, and the other is used for connection to the load side. Alternatively, the external terminal hole 91a and the external terminal hole 92a may be used for connection to a current path inside the load. The external terminal hole 91a and the external terminal hole 92a may be through holes that are approximately circular in plan view.

[0041] The first terminal 91 and the second terminal 92 can be made of, for example, copper, brass, nickel, or the like. From the viewpoint of increasing rigidity, brass is preferably used as the material for the first terminal 91 and the second terminal 92, and from the viewpoint of reducing electrical resistance, copper is preferably used. The first terminal 91 and the second terminal 92 may be made of the same material or different materials.

[0042] 7 is a vertical cross-sectional view showing a state in which the fuse element laminate 40 of the protection device 100 has been blown. The vertical cross-sectional view of FIG. 7 corresponds to the vertical cross-sectional view taken along line VI-VI' in FIG. 7, the central portions of the fusible conductive sheets 50a-50f of the fuse element laminate 40 are melted. When the central portions of the fusible conductive sheets 50a-50f melt, the first pressing member 71 presses upward, pushing the first insulating members 61a-61e and the second insulating pieces 63b of the second insulating members 62a, 62b. Furthermore, the second pressing member 72 presses downward, pushing the first insulating members 61a-61e and the first insulating pieces 63a of the second insulating members 62a, 62b. This brings the stacked first insulating pieces and the stacked second insulating pieces into close proximity and contact with each other, physically shielding the space of the current path and enabling the arc discharge generated by the melting of the fusible conductive sheets 50a-50f to be quickly extinguished.

[0043] (Protection element manufacturing method) The protective element 100 of this embodiment can be manufactured as follows. First, the fuse element laminate 40, positioned by the first holding member 30a and guide pins 41 or a jig of equivalent shape, and the first and second terminals 91 and 92 are prepared. Then, the first end 51 of each of the fusible conductive sheets 50a-50f of the fuse element laminate 40 is connected to the first terminal 91 by soldering. The second end 52 is also connected to the second terminal 92 by soldering. Known solder materials can be used for soldering, and it is preferable to use a solder material containing Sn as the main component in terms of resistivity, melting point, and environmental friendliness (lead-free). The connection between the first end 51 of each of the fusible conductive sheets 50a-50f and the first terminal 91, and the connection between the second end 52 of each of the fusible conductive sheets 50a-50f and the second terminal 92 are not limited to soldering, and known joining methods such as welding may also be used.

[0044] Next, a first holding member 30a and a second holding member 30b are prepared. The fuse element laminate 40, with the first terminal 91 and the second terminal 92 connected, is placed in the fuse element accommodating portion 37 of the first holding member 30a. At this time, the guide pin 41 of the fuse element laminate 40 is inserted into the guide pin insertion hole 38 of the first holding member 30a. Next, the second holding member 30b is placed on top of the first holding member 30a on which the fuse element laminate 40 is placed, so that the fuse element accommodating portion 37 of the second holding member 30b faces the fuse element laminate 40. At this time, the guide pin 41 of the fuse element laminate 40 is inserted into the guide pin insertion hole 38 of the second holding member 30b, and the protrusion 35 of the first holding member 30a is engaged with the recess 36 of the second holding member 30b, and the recess 36 of the first holding member 30a is engaged with the protrusion 35 of the second holding member 30b. In this manner, the holding member 30 is formed.

[0045] Next, prepare the first pressing member 71 and the second pressing member 72. The first pressing member 71 is housed in a compressed state in the pressing member insertion hole 39 of the first holding member 30a, and the second pressing member 72 is housed in a compressed state in the pressing member insertion hole 39 of the second holding member 30b.

[0046] Next, the cover 20 is prepared. The holding member 30 is inserted into the housing portion 22 of the cover 20. Next, adhesive is injected into the terminal adhesive injection port 33 of the holding member 30 to fill the gaps between the terminal mounting surface 32 and the first terminal 91 and second terminal. Additionally, adhesive is injected into the case adhesive injection port 34 and the inclined surface 21 of the cover 20 to bond the cover 20 and the holding member 30. For example, an adhesive containing a thermosetting resin can be used as the adhesive. In this way, the insulating case 10 is formed with the inside of the cover 20 sealed. Through the above steps, the protective element 100 of this embodiment is obtained.

[0047] In the protection element 100 of this embodiment, the fuse element laminate 40 includes a plurality of fusible conductive sheets 50a-50f arranged in parallel in the thickness direction, and each of the fusible conductive sheets 50a-50f is insulated by being in close proximity to or in contact (adhering tightly) with the first insulating members 61a-61e arranged therebetween. As a result, the current value flowing through each of the fusible conductive sheets 50a-50f is reduced and the space surrounding the fusible conductive sheets 50a-50f is extremely narrow, which tends to reduce the scale of arc discharge caused by melting. Therefore, the protection element 100 of this embodiment allows the insulating case 10 to be made smaller and lighter.

[0048] In the protective element 100 of this embodiment, when second insulating members 62a, 62b are arranged between the soluble conductive sheet 50a arranged at the bottom of the soluble conductive sheets 50a to 50f and the first holding member 30a of the insulating case 10, and between the soluble conductive sheet 50f arranged at the top of the soluble conductive sheets 50a to 50f and the second holding member 30b of the insulating case 10, the soluble conductive sheets 50a, 50f do not come into direct contact with the first holding member 30a and the second holding member 30b, respectively. As a result, arc discharge is less likely to cause the formation of carbides that serve as conductive paths on the inner surfaces of these insulating cases 10, and therefore leakage current is less likely to occur even if the size of the insulating case 10 is made smaller.

[0049] In the protection element 100 of this embodiment, if the first insulating members 61a-61e and the second insulating members 62a, 62b are separated at a position facing the center portion 53 between the first end portion 51 and the second end portion 52 of the soluble conductive sheets 50a-50f, it is possible to suppress the continuous adhesion of molten spatter to the surfaces of the first insulating members 61a-61e and the second insulating members 62a, 62b when the soluble conductive sheets 50a-50f melt and break at the center portion 53. This makes it possible to quickly extinguish the arc discharge generated by the melting of the soluble conductive sheets 50a-50f, and increase the insulation resistance of the protection element 100 after disconnection.

[0050] In the protection element 100 of this embodiment, by disposing the first pressing member 71 and the second pressing member 72, when the fusible conductive sheets 50a-50f melt, the fusible conductive sheets 50a-50f can be pressed and moved separately upward and downward. The melted portions (lost portions) on the first end portions 51 of the fusible conductive sheets 50a-50f come into close proximity with or contact the stacked first insulating pieces and the stacked second insulating pieces, physically shielding the space of the current path. This allows arc discharges generated by melting the fusible conductive sheets 50a-50f to be extinguished more quickly. While the protection element 100 of this embodiment includes the first pressing member 71 and the second pressing member 72, only one of the first pressing member 71 and the second pressing member 72 may be disposed.

[0051] In the protective element 100 of this embodiment, if at least one of the first insulating members 61a to 61e, the second insulating members 62a, 62b, the cover 20 of the insulating case 10, and the holding member 30 is formed from a material with a CTI index of 500 V or more, arc discharge will be less likely to cause the formation of carbides that serve as conductive paths on the surfaces of these components, making it less likely that leakage current will occur even if the size of the insulating case 10 is made smaller.

[0052] In the protection element 100 of this embodiment, if at least one of the first insulating members 61a to 61e, the second insulating members 62a, 62b, the cover 20 of the insulating case 10, and the holding member 30 is formed from a polyamide-based resin or a fluorine-based resin, polyamide-based resin and fluorine-based resin have excellent insulating properties and tracking resistance, making it easier to achieve both miniaturization and weight reduction.

[0053] In the protective element 100 of this embodiment, each of the fusible conductive sheets 50a-50f is a laminate including a low-melting-point metal layer and a high-melting-point metal layer. When the low-melting-point metal layer includes Sn and the high-melting-point metal layer includes Ag or Cu, the low-melting-point metal layer melts, and the high-melting-point metal is dissolved by Sn, thereby lowering the fusing temperature of the fusible conductive sheets 50a-50f. Furthermore, because Ag and Cu have higher physical strength than Sn, the physical strength of the fusible conductive sheets 50a-50f, in which a high-melting-point metal layer is laminated on a low-melting-point metal layer, is higher than the physical strength of the low-melting-point metal layer alone. Furthermore, because Ag and Cu have lower electrical resistivity than Sn, the electrical resistance of the fusible conductive sheets 50a-50f, in which a high-melting-point metal layer is laminated on a low-melting-point metal layer, is lower than the electrical resistance of the low-melting-point metal layer alone. In other words, the fuse element can handle larger currents.

[0054] In the protective element 100 of this embodiment, if each of the soluble conductive sheets 50a-50f is a laminate having two or more high-melting-point metal layers and one or more low-melting-point metal layers, with the low-melting-point metal layers arranged between the high-melting-point metal layers, the strength of the soluble conductive sheets 50a-50f is increased because of the high-melting-point metal layers on the outside. In particular, when the first end 51 and the first terminal 91 and the second end 52 and the second terminal 92 of the soluble conductive sheets 50a-50f are connected by soldering, the soluble conductive sheets 50a-50f are less likely to deform due to heat during soldering.

[0055] In the protective element 100 of this embodiment, when each of the soluble conductive sheets 50a-50f is a single layer containing silver or copper, the electrical resistivity tends to be lower than when the soluble conductive sheets are a laminate of a high-melting-point metal layer and a low-melting-point metal layer. Therefore, the soluble conductive sheets 50a-50f made of a single layer containing silver or copper can be made thinner even when they have the same electrical resistance and area as the soluble conductive sheets 50a-50f made of a laminate of a high-melting-point metal layer and a low-melting-point metal layer. When the soluble conductive sheets 50a-50f are thin, the amount of molten material that flies off when the soluble conductive sheets 50a-50f melt is proportionally smaller, resulting in higher insulation resistance after disconnection.

[0056] In the protection element 100 of this embodiment, each of the fusible conductive sheets 50a to 50f has a through hole 54 provided in a central portion 53, and has a fusing portion in which the cross-sectional area of ​​the central portion 53 in the current-carrying direction is smaller than the cross-sectional area of ​​the first end portion 51 and the second end portion 52 in the current-carrying direction. This stabilizes the portion that fuses when a current exceeding the rated current flows through the current path. Note that, although the protection element 100 of this embodiment has a through hole 54 provided in the central portion 53, there are no particular limitations on the method for reducing the cross-sectional area of ​​the central portion 53. For example, the cross-sectional area of ​​the central portion 53 may be reduced by cutting out both ends of the central portion 53 in a concave shape.

[0057] The protection element of the present invention is not limited to the above-described embodiment. For example, in the protection element 100 of the above-described embodiment, the insulating case 10 is cylindrical, but there are no particular limitations on the shape of the insulating case 10. The insulating case 10 may also be cubic. Furthermore, the fuse element laminate 40 is configured by stacking six fusible conductive sheets 50a to 50f, but there are no particular limitations on the number of fusible conductive sheets. The number of fusible conductive sheets may be two or more. The number of fusible conductive sheets may be, for example, within the range of two or more and ten or less. [Explanation of symbols]

[0058] 10 Insulation case 20 Cover 21 Slope 22 Storage section 30 Retaining member 30a First holding member 30b Second holding member 31a First end 31b Second end 32 Terminal mounting surface 33 Terminal adhesive injection port 34 Case adhesive injection port 34a Notch 35 Convex part 36 Recess 37 Fuse element housing 38 Guide pin insertion hole 39 Pressing member insertion hole 40 fuse element laminate 41 Guide pin 50a, 50b, 50c, 50d, 50e, 50f Fusible Conductive Sheet 51 First end 52 Second end 53 Central part 54 Through hole 61a, 61b, 61c, 61d, 61e First insulating member 62a, 62b Second insulating member 63a First insulating piece 63b Second insulating piece 64 Guide pin through hole 65 Gap 71 first pressing member 72 second pressing member 80 Internal pressure buffer space 91 1st terminal 92 2nd terminal 91a, 92a External terminal hole 100 Protection element

Claims

1. a fuse element laminate, an insulating case that houses the fuse element laminate, a first terminal, and a second terminal; the fuse element laminate includes a plurality of fusible conductive sheets arranged in parallel in a thickness direction, and a first insulating member arranged between each of the plurality of fusible conductive sheets in a state of being close to or in contact with the first insulating member, Each of the plurality of fusible conductive sheets has a first end and a second end facing each other, one end of the first terminal is connected to the first end and the other end is exposed to the outside from the insulating case, and one end of the second terminal is connected to the second end and the other end is exposed to the outside from the insulating case, A protective element, wherein the first insulating member is separated so as to block the direction from the first end toward the second end at a central portion between the first end and the second end of the fusible conductive sheet.

2. a second insulating member is disposed between the insulating case and a soluble conductive sheet disposed at the bottom of the plurality of soluble conductive sheets, and between the insulating case and a soluble conductive sheet disposed at the top of the plurality of soluble conductive sheets, 2. The protection element according to claim 1, wherein the second insulating member is separated so as to block the direction from the first end toward the second end at a central portion between the first end and the second end of the fusible conductive sheet.

3. The protection element according to claim 2 , further comprising a pressing member disposed inside the insulating case and pressing the second insulating member toward the soluble conductive sheet side.

4. 4. The protection element according to claim 2, wherein at least one of the first insulating member, the second insulating member, and the insulating case is formed from a material having a tracking resistance index CTI of 500V or more.

5. 4. The protection element according to claim 2, wherein at least one of the first insulating member, the second insulating member, and the insulating case is formed from a resin material selected from the group consisting of polyamide resins and fluorine-based resins.

6. A protective element according to any one of claims 1 to 5, wherein each of the plurality of fusible conductive sheets is a laminate including a low melting point metal layer and a high melting point metal layer, the low melting point metal layer including tin, and the high melting point metal layer including silver or copper.

7. 7. The protection element according to claim 6, wherein each of the plurality of fusible conductive sheets is a laminate having two or more high-melting-point metal layers and one or more low-melting-point metal layers, the low-melting-point metal layers being arranged between the high-melting-point metal layers.

8. 6. The protection element according to claim 1, wherein each of the plurality of soluble conductive sheets is a single layer containing silver or copper.

9. A protective element described in any one of claims 1 to 8, wherein each of the plurality of fusible conductive sheets has a fusion portion between the first end and the second end, and the cross-sectional area of ​​the fusion portion in the current flow direction is smaller than the cross-sectional area of ​​the first end and the second end in the current flow direction from the first end to the second end.

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