protective element

Abstract

To provide a protective element that can stop arc discharge in a short time when interrupting overcurrents of 200V or more without increasing the size of the protective element. [Solution] The protective element 1 comprises a heating substrate 10 having an insulating substrate 11, a heating element 12 formed on the insulating substrate 11, a first connecting electrode 14 and a second connecting electrode 15 formed on the surface of the insulating substrate 11 and electrically connected to the heating element 12, and an end electrode 16 formed on the end face of the insulating substrate 11 and not electrically connected to the heating element; a first power supply member 21 connected to the first connecting electrode 14, a second power supply member 22 connected to the second connecting electrode 15, a fusible conductor 30 connected to the end electrode 16, a first terminal 41 and a second terminal 42 connected to both ends of the fusible conductor 30, and a case 50 that houses the heating substrate 10, the fusible conductor 30, a part of the first power supply member 21, at least a part of the second power supply member 22, a part of the first terminal 41, and a part of the second terminal 42.

Description

Technical Field

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

Background Art

[0002] Conventionally, there is a fuse element that generates heat and melts to cut off the current path when a current exceeding the rating flows through the current path. A protection element (fuse element) having a fuse element is 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 device applications to electric vehicles (EVs) and storage batteries, and are becoming larger in capacity. With the increase in the capacity of lithium-ion batteries, the voltage has become a high-voltage specification of several hundred volts, and a large-current specification of several hundred amperes to several thousand amperes is required for the current.

[0004] Patent Document 1 discloses a protection element corresponding to a large current that melts a fuse element by overcurrent or heating of a heating element. In this protection element, an electrode formed on a wide surface of a heat-generating substrate is connected to the fuse element.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] One of the factors that causes arc discharge to continue is the formation of conductive paths by molten fragments of the fuse element adhering to the surface of the heating substrate. In the configuration of Patent Document 1, the heating substrate has a long and wide surface area in the direction of current flow. When conductive paths are formed on the wide surface of this heating substrate, the potential of this surface becomes approximately equal, and the applied voltage is applied to the narrow gap between the heating substrate and the external electrode. In this case, the electric field strength becomes very high, making it difficult to stop the arc discharge. In the configuration of Patent Document 1, when the voltage exceeds 200V, it becomes difficult to stop the arc discharge early, and it becomes difficult to properly shut off the protective element. Therefore, to increase the voltage of the protective element, it is necessary to widen the gap between the heating substrate and the external electrode in order to keep the electric field strength of the fuse element's interrupting portion low. However, simply widening the gap results in a longer fuse element. In this case, the electrical resistance value of the protective element increases, and the rated current value decreases. Furthermore, the electrical resistance can be reduced by widening the fuse element. However, this increases the size of the protective element and thus the cost.

[0007] One of the objectives of this invention is to provide a protective element that can stop arc discharge in a short time when interrupting overcurrents of 200V or more without increasing the size of the protective element. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides the following means.

[0009] [Aspect 1 of the present invention] Insulating substrate and A heating element formed on the insulating substrate, A first connecting electrode and a second connecting electrode are formed on the surface of the insulating substrate and are electrically connected to the heating element, A heating substrate having an end electrode formed on the end face of the insulating substrate and not electrically connected to the heating element, A first power supply member connected to the first connecting electrode, and a second power supply member connected to the second connecting electrode, A fusible conductor connected to the end face electrode, The first terminal and the second terminal connected to both ends of the fusible conductor, The device comprises a heating substrate, a fusible conductor, a part of the first power supply member, at least a part of the second power supply member, a part of the first terminal, and a case that houses the second terminal. Protective element.

[0010] [Aspect 2 of the present invention] The heating element is formed on the surface of the insulating substrate, The first connecting electrode and the second connecting electrode are electrically connected to both ends of the heating element. The heating substrate further comprises an insulating layer laminated on the surface of the heating element. The protective element described in Embodiment 1.

[0011] [Aspect 3 of the present invention] The heating element is formed inside the insulating substrate, The insulating substrate has first through-holes and second through-holes formed therein, connecting both ends of the heating element to the surface of the insulating substrate. The first connecting electrode is electrically connected to the heating element via the first through-hole. The second connecting electrode is electrically connected to the heating element via the second through-hole. The protective element described in Embodiment 1.

[0012] [Aspect 4 of the present invention] In the aforementioned case, an internal pressure buffer space is formed that is connected to a leak area that overlaps with a portion of the fusible conductor, and has a larger volume than the leak area. A protective element according to any one of embodiments 1 to 3.

[0013] [Aspect 5 of the present invention] The case comprises a first case and a second case that sandwich the fusible conductor from both sides in a direction perpendicular to the direction of current flow of the fusible conductor, Parts of the first case and the second case are in contact with or close to the fusible conductor. The protective element according to any one of Aspects 1 to 4.

[0014] [Aspect 6 of the present invention] The case further includes a third case and a fourth case that cover both sides of the combined body of the first case and the second case in a direction orthogonal to the bonding direction of the combined body to fix the bonded state of the first case and the second case. The protective element according to Aspect 5.

[0015] [Aspect 7 of the present invention] The first case and the second case are made of a polyamide-based resin or a fluorine-based resin. The protective element according to Aspect 5 or 6.

[0016] [Aspect 8 of the present invention] The soluble conductor is a laminate including a high melting point metal layer and a low melting point metal layer. The protective element according to any one of Aspects 1 to 7.

[0017] [Aspect 9 of the present invention] The high melting point metal layer is made of Ag or Cu, or a metal mainly composed of Ag or Cu. The low melting point metal layer is made of Sn or a metal mainly composed of Sn. The protective element according to Aspect 8.

[0018] [Aspect 10 of the present invention] The heating substrate further includes a lead-in electrode formed on the front surface and / or the back surface of the insulating substrate, connected to the end face electrode, and not electrically connected to the heating element. The protective element according to any one of Aspects 1 to 9.

[0019] [Aspect 11 of the present invention] It has a first conductor and a second conductor connected to both ends of the soluble conductor. The first conductor is connected to the first terminal. The second conductor is connected to the second terminal. The melting temperature of the fusible conductor is lower than the melting temperatures of the first and second conductors. A protective element according to any one of the embodiments 1 to 10. [Effects of the Invention]

[0020] According to the above-mentioned aspect of the present invention, it is possible to provide a protective element that can stop arc discharge in a short time when interrupting an overcurrent of 200V or more without increasing the size of the protective element. [Brief explanation of the drawing]

[0021] [Figure 1] This is a diagram showing a protective element of the first embodiment, and is a cross-sectional view II of Figure 2. [Figure 2] This is a top view of the protective element of the first embodiment during assembly. [Figure 3] This is a side view of the protective element of the first embodiment, and is a view taken from arrow III in Figure 1. [Figure 4] This figure shows a heating substrate of the first embodiment, and is a view taken from arrow IV in Figure 2. [Figure 5] Figure 4 is a VV cross-sectional view. [Figure 6A] This is a circuit diagram illustrating the effect of the protective element. [Figure 6B] Here is another example of a circuit diagram for a protective element. [Figure 7] This figure shows a protective element of the second embodiment and is a cross-sectional view corresponding to Figure 1. [Figure 8] This figure shows a heating substrate of the second embodiment, and corresponds to Figure 4. [Figure 9] This is a cross-sectional view taken along line IX-IX in Figure 8. [Figure 10] This figure illustrates the effect of the heating substrate of the second embodiment. [Figure 11] This figure shows a protective element of the third embodiment and is a cross-sectional view corresponding to Figure 1. [Figure 12] This figure shows a heating substrate of the third embodiment and corresponds to Figure 4. [Figure 13] This is a cross-sectional view taken along line XIII-XIII in Figure 12. [Figure 14] This figure illustrates the effect of the heating substrate of the third embodiment. [Figure 15] This figure shows a protective element of the fourth embodiment and is a cross-sectional view corresponding to Figure 1. [Figure 16] This figure shows a heating substrate of the fourth embodiment, and corresponds to Figure 4. [Figure 17] This is a cross-sectional view taken along line XVII-XVII in Figure 16. [Figure 18] This figure illustrates the effect of the heating substrate of the fourth embodiment. [Figure 19] This figure shows a protective element of the fifth embodiment and is a cross-sectional view corresponding to Figure 1. [Figure 20] This figure shows a protective element of the sixth embodiment and is a cross-sectional view corresponding to Figure 1. [Modes for carrying out the invention]

[0022] The embodiments will be described in detail below, with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience to clearly illustrate the features, and the dimensional ratios of each component may differ from those in reality. The materials, dimensions, etc., exemplified in the following description are examples only, and the present invention is not limited to them. It is possible to modify and implement the invention as appropriate within the scope of achieving its effects.

[0023] (First Embodiment) A protective element 1 according to one embodiment of the present invention will be described with reference to Figures 1 to 6. The protective element 1 of this embodiment constitutes a part of a high-voltage, high-current (100V / 100A or more) electrical circuit that uses a lithium-ion secondary battery, for example. The protective element 1 is installed, for example, in an electric vehicle (EV).

[0024] Referring to Figures 1 to 6, the protective element 1 comprises a heating substrate 10, a first power supply member 21 and a second power supply member 22, a fusible conductor 30, a first terminal 41 and a second terminal 42, and a case 50. The first terminal 41 and the second terminal 42 are arranged apart from each other in a predetermined direction. Each of the first terminal 41 and the second terminal 42 is plate-shaped.

[0025] The protective element 1 has two mechanisms for interrupting the current path: an overcurrent interruption mechanism that interrupts the current path by melting the fusible conductor 30 when an overcurrent (a current exceeding a predetermined value) flows through the fusible conductor 30 constituting the fuse element, and an active interruption mechanism that interrupts the current path by supplying current to the heating substrate 10 and generating heat, thereby melting the fusible conductor 30 when an abnormality other than an overcurrent occurs.

[0026] In the following, we will set the XYZ Cartesian coordinate system (3D Cartesian coordinate system) in each figure and explain each configuration. The predetermined direction in which the first terminal 41 and the second terminal 42 are aligned is called the front-to-back direction. The front-to-back direction corresponds to the X-axis direction in each figure. Of the X-axis directions, the direction from the second terminal 42 toward the first terminal 41 (-X side) is called the front side, and the direction from the first terminal 41 toward the second terminal 42 (+X side) is called the rear side. The front-to-back direction is the direction connecting the first terminal 41 and the second terminal 42, and is also the direction in which electricity flows when the protection element 1 is in use, so it can also be referred to as the direction of current flow.

[0027] The direction in which the plates of the first terminal 41 and the second terminal 42 face is called the up-down direction. The up-down direction is perpendicular to the front-back direction and corresponds to the Z-axis direction in each figure. Of the up-down directions, the upper side corresponds to the +Z side and the lower side corresponds to the -Z side.

[0028] The direction perpendicular to the front-back and up-down directions is called the left-right direction. In each diagram, the left-right direction corresponds to the Y-axis direction. Of the left-right directions, the left side corresponds to the -Y side, and the right side corresponds to the +Y side. More specifically, the -Y side is the left side when the protection element 1 is viewed from the rear (+X side), and the +Y side is the right side when the protection element 1 is viewed from the rear. The left-right direction can also be referred to as the width direction. In this case, for example, one side of the width direction corresponds to the -Y side, and the other side of the width direction corresponds to the +Y side.

[0029] In this embodiment, the terms front, rear, top, bottom, left, and right are merely convenient names used to clearly explain the relative positional relationships of each component, and the actual arrangement may differ from those indicated by these names.

[0030] (1st terminal, 2nd terminal) Each of the first terminal 41 and the second terminal 42 is plate-shaped, extending in the vertical and perpendicular plane directions (XY plane directions). In the example shown in the figure, each of the first terminal 41 and the second terminal 42 is approximately rectangular in shape. The first terminal 41 and the second terminal 42 are positioned apart from each other in the front-to-back direction. The first terminal 41 and the second terminal 42 are connected to both ends of the fusible conductor 30 in the front-to-back direction.

[0031] The rear end of the first terminal 41 is connected to the front end of the fusible conductor 30. The rear end of the first terminal 41 is connected to the front end of the fusible conductor 30 by, for example, soldering. The front portion of the first terminal 41 protrudes forward from the case 50 and is exposed to the outside of the case 50. The front end of the second terminal 42 is connected to the rear end of the fusible conductor 30. The front end of the second terminal 42 is connected to the rear end of the fusible conductor 30 by, for example, soldering. The rear portion of the second terminal 42 protrudes to the rear from the case 50 and is exposed to the outside of the case 50. Screw holes may be formed in the portions of the first terminal 41 and the second terminal 42 that are exposed to the outside of the case 50.

[0032] The first terminal 41 and the second terminal 42 may be substantially the same shape or may be different shapes. The thickness dimensions (vertical dimensions) of the first terminal 41 and the second terminal 42 are not particularly limited, but may be several hundred micrometers to several millimeters, for example. The thickness dimensions of the first terminal 41 and the second terminal 42 may be the same or different. The dimensions of the first terminal 41 and the second terminal 42 can be changed according to the design specifications.

[0033] Each of the first terminal 41 and the second terminal 42 is made of a metal such as copper, brass, or nickel. From the viewpoint of increasing rigidity, brass is preferably used for the first terminal 41 and the second terminal 42, and from the viewpoint of reducing electrical resistance, copper is preferably used. When using copper, it is preferable to apply a rust-preventive treatment such as nickel plating, silver plating, or tin plating to the surface. The first terminal 41 and the second terminal 42 may be made of the same material or of different materials. The materials of the first terminal 41 and the second terminal 42 can be changed according to the design specifications.

[0034] (Fusible conductor) The fusible conductor 30 is made of a metal plate-shaped member, sheet-shaped member, or metal foil, etc. In the example shown in the figure, only one fusible conductor 30 is provided, but this is not limited to this. For example, two fusible conductors 30 may be provided side by side in the left-right direction, or three or more may be provided side by side. The installation configuration of the fusible conductor 30 can be changed according to the design specifications.

[0035] The fusible conductor 30 is plate-shaped, sheet-shaped, or foil-shaped, and extends in the vertical direction and the plane direction perpendicular to it (XY plane direction). In the example shown in the figure, the fusible conductor 30 has the shape of a rectangular plate when viewed from the vertical direction, with the front-to-back dimension being larger than the left-to-right dimension.

[0036] The fusible conductor 30 is connected to the end electrode 16 of the heating substrate 10. The central part of the fusible conductor 30 in the front-to-back direction is connected to the end electrode 16 of the heating substrate 10, for example, by soldering. In the example shown in the figure, the lower surface of the end electrode 16 is connected to the central part of the fusible conductor 30 in the front-to-back direction. That is, the upper surface of the central part of the fusible conductor 30 in the front-to-back direction and the lower surface of the end electrode 16 are connected to each other.

[0037] For example, the fusible conductor 30 is made of Sn (tin) or a metal mainly composed of Sn. Although not shown in the figures, the fusible conductor 30 may be a laminate containing a high-melting-point metal layer and a low-melting-point metal layer. This laminate may have one or more low-melting-point metal layers and two or more high-melting-point metal layers, with the low-melting-point metal layers arranged between the high-melting-point metal layers. This laminate may be formed, for example, by coating the low-melting-point metal layer with a high-melting-point metal layer.

[0038] For example, the high-melting-point metal layer of the above laminate consists of Ag (silver) or Cu (copper), or a metal mainly composed of Ag or Cu. The high-melting-point metal layer of the above laminate only needs to contain Ag or Cu, and may be pure Ag, pure Cu, an Ag alloy, or a Cu alloy. An Ag alloy is an alloy in which Ag has the highest content among the metals contained in the alloy, and a Cu alloy is an alloy in which Cu has the highest content among the metals contained in the alloy.

[0039] For example, the low-melting-point metal layer of the above-mentioned laminate is made of Sn or a metal mainly composed of Sn. The low-melting-point metal layer of the above-mentioned laminate only needs to contain Sn, and may be pure Sn or a Sn alloy. A Sn alloy is an alloy mainly composed of Sn. A Sn alloy is an alloy in which Sn has the highest content among the metals contained in the alloy. Examples of Sn alloys include Sn-Bi alloy, In-Sn alloy, Sn-Ag-Cu alloy, etc.

[0040] The above laminate may have a two-layer structure consisting of a low-melting-point metal layer and a high-melting-point metal layer. Alternatively, the above laminate may have a multilayer structure of three or more layers, with two or more high-melting-point metal layers and one or more low-melting-point metal layers, with the low-melting-point metal layers positioned between the high-melting-point metal layers. Furthermore, the fusible conductor 30 may be composed of a single layer of a low-melting-point metal containing Sn.

[0041] In the example shown in the figure, the rear end of the first terminal 41 is fixed to the front end of the fusible conductor 30. That is, the lower surface of the rear end of the first terminal 41 and the upper surface of the front end of the fusible conductor 30 are connected to each other. Furthermore, the front end of the second terminal 42 is fixed to the rear end of the fusible conductor 30. That is, the lower surface of the front end of the second terminal 42 and the upper surface of the rear end of the fusible conductor 30 are connected to each other. The fusible conductor 30 is positioned on the underside of the first terminal 41 and the second terminal 42 and spans between them. The vertical relationship of the connections between the fusible conductor 30 and the first terminal 41 and the second terminal 42 is not limited to this. For example, the fusible conductor 30 may be positioned on the upper side of the first terminal 41 and the second terminal 42.

[0042] Although not shown in the figures, a first conductor (a metal conductor whose front end is connected to the first terminal 41) and a second conductor (a metal conductor whose rear end is connected to the second terminal 42) may be connected to both ends of the fusible conductor 30 in the front-rear direction. The first conductor, the fusible conductor 30, and the second conductor are connected in series in this order to form the current path of the fuse element. The fusible conductor 30 functions as the fused part of the fuse element during overcurrent interruption and active interruption, respectively. For example, it is preferable that the fusible conductor 30 is made of a material with a lower melting temperature than each of the first and second conductors. For example, it is preferable that the fusible conductor 30 has a higher electrical resistivity than each of the first and second conductors.

[0043] (heating substrate) The heating substrate 10 is energized and heated by a current control element provided in the external circuit when it becomes necessary to interrupt the current supply path due to an abnormality in the external circuit that serves as the current supply path for the protection element 1, or due to other reasons (such as a collision accident or temperature anomaly). In the example shown in the figure, the heating substrate 10 is plate-shaped, with a pair of plate surfaces facing in the front-to-back direction. When viewed from the front-to-back direction, the heating substrate 10 has a rectangular plate shape in which the left-to-right dimension is larger than the up-to-down dimension. The heating substrate 10 is placed in the substrate housing space 63 of the case 50. In other words, the heating substrate 10 is housed in the case 50.

[0044] Referring together to Figures 4 and 5, the heating substrate 10 includes an insulating substrate 11, a heating element 12 formed on the surface of the insulating substrate 11, an insulating layer 13 laminated on the surface of the heating element 12, a first connecting electrode 14 and a second connecting electrode 15 formed on the surface of the insulating substrate 11 and electrically connected to both ends of the heating element 12, and an end electrode 16 formed on the end face of the insulating substrate 11 and not electrically connected to the heating element 12.

[0045] The insulating substrate 11 is an insulating substrate such as alumina, glass ceramics, mullite, or zirconia. However, the material of the insulating substrate 11 is not limited to those mentioned above and can be changed according to the design specifications.

[0046] The insulating substrate 11 has a rectangular shape that is larger than the heating element 12 when viewed from the front-to-back direction. In the example shown in the figure, the insulating substrate 11 has a rectangular shape in which the left-to-right dimension is larger than the up-to-down dimension. Specifically, the insulating substrate 11 has thickness in the direction parallel to the direction of current flow through the fuse element (generally the front-to-back direction), extends in the direction intersecting the direction of current flow, and in the example shown in the figure, has its longest side in the direction perpendicular to the direction of current flow (left-to-right direction). Note that the shape of the insulating substrate 11 is not limited to the above and can be changed according to the design specifications.

[0047] The heating element 12 is made of a conductive material that generates heat when an electric current is applied, such as nichrome, W, Mo, Ru, or a material containing these materials. The heating element 12 can be formed by mixing powdered alloys, compositions, or compounds of these materials with a resin binder to form a paste, then creating a pattern on the insulating substrate 11 using screen printing technology and firing it. The material of the heating element 12 is not limited to the above and can be changed according to the design specifications.

[0048] The heating element 12 extends horizontally when viewed from the front-to-back direction. In the example shown in the figure, the heating element 12 has a rectangular shape, with its horizontal dimension being larger than its vertical dimension. Note that the shape of the heating element 12 is not limited to the above and can be changed according to the design specifications.

[0049] The heating element 12 is formed on the front surface of the insulating substrate 11. Specifically, the heating element 12 is positioned on the front surface of the insulating substrate 11, slightly below the vertical center, and spaced apart from the top, bottom, left, and right edges of the insulating substrate 11. When viewed from the front side of the insulating substrate 11, the heating element 12 is positioned such that the distance between it and the lower edge of the insulating substrate 11 is narrower than the distance between it and the upper edge of the insulating substrate 11, and the distances between it and the left and right edges of the insulating substrate 11 are equal. Note that the arrangement of the heating element 12 is not limited to the above and can be changed according to the design specifications.

[0050] The insulating layer 13 is laminated on the front surface of the heating element 12 on the front surface of the insulating substrate 11. The insulating layer 13 is provided to protect the heating element 12. As the material of the insulating layer 13, insulating materials such as ceramics and glass can be used. The insulating layer 13 can be formed by applying an insulating material paste and firing it, etc. However, the material of the insulating layer 13 is not limited to the above and can be changed according to the design specifications.

[0051] In the example shown in the figure, the insulating layer 13 has a rectangular shape that is larger than the heating element 12 and smaller than the insulating substrate 11 when viewed from the front side of the insulating substrate 11. Specifically, the insulating layer 13 has a rectangular shape that is larger than the top, bottom, left, and right dimensions of the heating element 12 when viewed from the front side of the insulating substrate 11, smaller than the top, bottom, left, and right dimensions of the insulating substrate 11, and is elongated in the left-right direction. Note that the shape of the insulating layer 13 is not limited to the above and can be changed according to the design specifications.

[0052] The first connecting electrode 14 and the second connecting electrode 15 are electrically connected to both ends of the heating element 12 in the left-right direction on the front surface of the insulating substrate 11. When viewed from the front side of the insulating substrate 11, the first connecting electrode 14 and the second connecting electrode 15 have a rectangular portion located on the upper end of the insulating substrate 11 and a portion that extends downward from the lower end of this portion and is connected to the heating element 12.

[0053] In the example shown in the figure, the first connecting electrode 14 and the second connecting electrode 15 are spaced apart from each other in the left-right direction when viewed from the front side of the insulating substrate 11, and have opposite shapes. Parts of the first connecting electrode 14 and the second connecting electrode 15 are exposed to the outside of the heating substrate 10 without being covered by the insulating layer 13. Note that the shapes of the first connecting electrode 14 and the second connecting electrode 15 are not limited to those shown above and can be changed according to the design specifications.

[0054] The end electrode 16 is formed on the lower end surface of the insulating substrate 11. The end electrode 16 is electrically insulated from the heating element 12, the first connecting electrode 14, and the second connecting electrode 15 on the front side of the insulating substrate 11. When viewed from the front side of the insulating substrate 11, the upper edge of the end electrode 16 is positioned below the lower edge of the heating element 12. The end electrode 16 may also be referred to as a dummy electrode.

[0055] In the example shown in the figure, the end electrode 16 has a rectangular shape, with its left-right dimension being larger than its front-to-back dimension. In the example shown in the figure, the front-to-back dimension of the end electrode 16 is the same as the thickness (front-to-back dimension) of the insulating substrate 11, and it has the same left-to-right dimension as the insulating substrate 11. Note that the shape of the end electrode 16 is not limited to the above and can be changed according to the design specifications.

[0056] (First power supply member, second power supply member) The first power supply member 21 and the second power supply member 22 are members that supply power to the heating substrate 10. Each of the first power supply member 21 and the second power supply member 22 extends from the outside to the inside of the case 50. One end of the first power supply member 21 is connected to the first connection electrode 14 of the heating substrate 10. One end of the first power supply member 21 is connected to the portion of the first connection electrode 14 that is exposed to the outside (the rectangular portion), for example by soldering. One end of the second power supply member 22 is connected to the second connection electrode 15 of the heating substrate 10. One end of the second power supply member 22 is connected to the portion of the second connection electrode 15 that is exposed to the outside (the rectangular portion), for example by soldering.

[0057] In the example shown in the figure, at least a portion of the power supply members 21 and 22 is made up of electric wires (wiring members), but this is not limited to this. For example, although not shown, at least a portion of the power supply members 21 and 22 may be made up of conductive plate-shaped members or rod-shaped members. The configuration of the power supply members 21 and 22 can be changed according to the design specifications.

[0058] Power is supplied from the power supply members 21 and 22 to the connecting electrodes 14 and 15. When the heating element 12 generates heat, the heat is transferred to the end electrode 16 via the insulating substrate 11, and the end electrode 16 is heated. The lower surface of the end electrode 16 is connected to the center of the fusible conductor 30 in the front-to-back direction. When the heating element 12 generates heat due to the cutoff signal, the center of the fusible conductor 30 in the front-to-back direction remains connected to the end electrode 16. If the amount of heat generated by the heating element 12 is large, the center of the fusible conductor 30 in the front-to-back direction connected to the end electrode 16 also melts, and a portion of the molten fusible conductor 30 is retained on the lower surface of the end electrode 16.

[0059] In this embodiment, the heating element 12 generates heat when current is applied, and this heat is transferred to the end electrode 16 (dummy electrode) via the insulating substrate 11, causing a portion of the fusible conductor 30 superimposed on the end electrode 16 to melt. As a result, when the heating element 12 generates heat due to a cutoff signal, a portion of the fusible conductor 30 can be efficiently melted and cut.

[0060] (case) The case 50 houses the heat-generating substrate 10, the fusible conductor 30, a part of the first power supply member 21, at least a part of the second power supply member 22, a part of the first terminal 41, and a part of the second terminal 42. The case 50 has a columnar shape that extends in the front-to-back direction. The case 50 has an internal pressure buffer space 61 that is connected to a leak area that overlaps with a part of the fusible conductor 30 and has a larger volume than the leak area.

[0061] The case 50 has a space for housing the fusible conductor 30 (conductor housing space 60), an internal pressure buffer space 61 that is connected to the conductor housing space 60 through a leak hole and / or gap (leak area space 62), and a space for housing the heat-generating substrate 10 (substrate housing space 63).

[0062] Case 50 comprises a first case 51 and a second case 52 that sandwich the fusible conductor 30 from both sides in a direction perpendicular to the direction of current flow of the fusible conductor 30, and a third case 53 and a fourth case 54 that cover the joint of the first case 51 and the second case 52 from both sides in a direction perpendicular to the direction of joint of the joint, fixing the joint state of the first case 51 and the second case 52. Parts of the first case 51 and the second case 52 are in contact with or close to the fusible conductor 30.

[0063] For example, the proximity distance (proximity distance) between a portion of the first case 51 and the second case 52 and the fusible conductor 30 is 1 mm or less, preferably 0.5 mm or less, and more preferably 0.1 mm or less. The proximity distance is the value obtained by subtracting the thickness of the fusible conductor 30 from the distance of the gap between the first case 51 and the second case 52 that sandwich the fusible conductor 30.

[0064] The first case 51 and the second case 52 are stacked vertically. The first case 51 and the second case 52 are positioned on both sides of the fusible conductor 30 in the vertical direction. The first case 51 is positioned below the first terminal 41, the second terminal 42, and the fusible conductor 30. The first case 51 has an internal pressure buffering space 61 and a leak space (leak space 62). The lower surface of the first case 51 constitutes the open surface of the internal pressure buffering space 61. The first case 51 includes a terminal mounting surface 51a and a conductor opposing recess 51c.

[0065] The terminal mounting surface 51a extends in the vertical direction and in the plane direction perpendicular to it (XY plane direction). A pair of terminal mounting surfaces 51a are provided at intervals on both ends of the first case 51 in the front-to-back direction.

[0066] The conductor-facing recess 51c is a concave shape that is recessed on the lower side of the upper surface of the first case 51 so as to follow the fusible conductor 30. The conductor-facing recess 51c is a rectangular hole that opens to the upper surface. The bottom surface of the conductor-facing recess 51c is a flat surface facing upward and extends in the plane direction perpendicular to the vertical direction (XY plane direction). The bottom surface of the conductor-facing recess 51c faces the lower surface of the fusible conductor 30. The conductor-facing recess 51c is located on the front-to-back side of the first case 51, closer to the center in the front-to-back direction than the terminal mounting surface 51a. The dimensions of the conductor-facing recess 51c in the front-to-back and left-to-right directions are approximately the same as the dimensions of the fusible conductor 30 in the front-to-back and left-to-right directions.

[0067] The second case 52 is positioned above the first terminal 41, the second terminal 42, and the fusible conductor 30. The upper surface of the second case 52 constitutes the open surface of the substrate housing space 63. The second case 52 has a terminal retaining surface 52a and a terminal locking portion 52b.

[0068] The terminal retaining surface 52a is concave, recessed upward from the lower surface of the second case 52. The bottom surface of the terminal retaining surface 52a is planar and faces downward, extending in the plane direction perpendicular to the vertical direction (XY plane direction). A pair of terminal retaining surfaces 52a are provided at intervals on both ends of the second case 52 in the front-rear direction.

[0069] The terminal locking portion 52b is provided on the side wall of the left-right outer portion of the second case 52. The terminal locking portion 52b is located on the lower surface of the second case 52 and on the wall surface along the portion of the side wall that opens inward in the left-right direction. There are two pairs of terminal locking portions 52b (a total of four) on both the left and right sides of the second case 52 in the front-rear direction.

[0070] For example, terminal protrusions that project outward in the left-right direction may be formed in the portion of the case 50 in which the first terminal 41 and the second terminal 42 are housed. The second case 52 may have recesses formed in which the terminal protrusions of the first terminal 41 and the second terminal 42 are housed. This allows the second case 52 to be connected to the first case 51, preventing the first terminal 41 and the second terminal 42 from coming loose or falling out.

[0071] The third case 53 and the fourth case 54 are cylindrical in shape, extending in the front-to-back direction. In the example shown in the figure, the third case 53 and the fourth case 54 are cylindrical in shape, opening in the front-to-back direction. The third case 53 and the fourth case 54 cover the combined body, which is formed by joining the first case 51 and the second case 52 in the vertical direction, from both sides in the front-to-back direction, fixing the joined state of the first case 51 and the second case 52. The third case 53 and the fourth case 54 hold the joined state of the first case 51 and the second case 52 in a fixed state by adhesive or the like.

[0072] For example, case 50 can be assembled using the following procedure. First, the first terminal 41, the second terminal 42, the fusible conductor 30, the heating substrate 10, and the power supply members 21 and 22 are sandwiched from above and below by the first case 51 and the second case 52. Next, both terminal sides (outside in the front-to-back direction) are inserted into the cylindrical third case 53 and fourth case 54 and fixed in place.

[0073] In the combined state of the first case 51 and the second case 52, a conductor housing space 60 is formed between the first case 51 and the second case 52. A fusible conductor 30 is housed in the conductor housing space 60.

[0074] A portion of the upper surface of the first case 51 (a portion of the surface facing the conductor housing space 60) is configured to be in contact with or close to the lower surface of a portion of the fusible conductor 30 other than the leak area. A portion of the lower surface of the second case 52 (a portion of the surface facing the conductor housing space 60) is configured to be in contact with or close to the upper surface of a portion of the fusible conductor 30 other than the leak area (a portion other than the substrate housing space 63).

[0075] With the third case 53 and fourth case 54 connected to the combined body of the first case 51 and the second case 52, an internal pressure buffer space 61 and a leak space 62 are formed between the lower parts of the first case 51, the third case 53, and the fourth case 54.

[0076] The internal pressure buffering space 61 is a rectangular parallelepiped space that connects to the conductor housing space 60 via the leak space 62. For example, the vertical dimension of the internal pressure buffering space 61 is, for example, 1 / 10 to 1 / 2 of the overall vertical dimension (outer height) of the protective element 1. The internal pressure buffering space 61 has the effect of suppressing the rapid rise in internal pressure of the protective element 1 caused by the gas generated by the arc discharge that occurs when the fusible conductor 30 is cut.

[0077] In the example shown in the figure, the leak space 62 has an opening in the vertical direction in the portion of the first case 51 that overlaps with the central part of the fusible conductor 30 in the front-to-back direction. For example, the opening area of ​​the leak space 62 (the cross-sectional area when the leak hole and / or gap is cut by a plane perpendicular to the vertical direction) is 20% or less of the length in the direction of current flow in the area where the fusible conductor 30 and the case 50 are in contact or close proximity, and there is no restriction outside the area where the case 50 and the fusible conductor 30 are in contact or close proximity. Note that the configuration of the leak hole and / or gap (number, location, shape, opening area, etc.) is not limited to the above and can be changed according to the design specifications. Furthermore, ventilation passages may be formed in the areas where the first case 51, the third case 53, and the fourth case 54 face each other, in order to reduce the pressure in the internal pressure buffering space 61.

[0078] With the third case 53 and fourth case 54 attached to the combined body of the first case 51 and the second case 52, a substrate housing space 63 is formed between the upper parts of the second case 52, the third case 53, and the fourth case 54.

[0079] In the example shown in the figure, the substrate housing space 63 is opened vertically in the portion of the second case 52 that overlaps with the central part of the fusible conductor 30 in the front-to-back direction. The substrate housing space 63 is formed on the central side in the front-to-back direction of the second case 52. The substrate housing space 63 is a rectangular parallelepiped space that is larger than the heating substrate 10 and longer in the left-to-right direction. Note that the configuration of the substrate housing space 63 (location, shape, etc.) is not limited to the above and can be changed according to the design specifications.

[0080] For example, in case 50 (first case 51, second case 52, third case 53, and fourth case 54), it is preferable that the material is formed with a tracking resistance index CTI (resistance to tracking (carbonized conductive path) failure) of 500V or higher. The tracking resistance index CTI can be determined by testing according to IEC60112.

[0081] A resin material can be used for case 50. Resin materials have a lower heat capacity and melting point than ceramic materials. For this reason, using a resin material for case 50 is preferable because it has the characteristic of weakening arc discharge due to gasification cooling (ablation), and when molten and scattered metal particles adhere to case 50, the surface of case 50 deforms or the attached material aggregates, causing the metal particles to become sparse and making it difficult to form conduction paths.

[0082] As the resin material, for example, polyamide resins or fluororesins can be used. For example, the first case 51 and the second case 52 are made of polyamide resin or fluororesin. The polyamide resin may be an aliphatic polyamide or a semi-aromatic polyamide. Examples of aliphatic polyamides include nylon 4, nylon 6, nylon 46, and nylon 66. Examples of semi-aromatic polyamides include nylon 6T, nylon 9T, and polyphthalamide (PPA) resin. An example of a fluororesin is polytetrafluoroethylene. Furthermore, polyamide resins and fluororesins have high heat resistance and are not easily combustible. In particular, aliphatic polyamides do not easily produce graphite even when burned. For this reason, by forming case 50 using aliphatic polyamide, it is possible to more reliably prevent the formation of a new current path by graphite generated by the arc discharge when the fuse element blows.

[0083] (filling material) A filler material 70 may be placed in at least a portion of the internal pressure buffering space 61. The filler material 70 has the function of filtering and cooling the metal gas generated by the arc discharge that occurs in the part of a circuit where an excessive current is flowing that is to be interrupted, thereby quickly and safely extinguishing the arc discharge.

[0084] For example, the filler 70 may include plate-shaped members (e.g., plate-shaped ceramics) made of ceramic materials such as quartz glass, alumina, or zirconia. Although not shown in the figures, multiple plate-shaped ceramics may be stacked in the front-to-back or up-and-down direction.

[0085] For example, the filler 70 may include a filter. The filter has the function of suppressing the rise in internal pressure by collecting molten material generated by arc discharge occurring at the point where an excessive current is to be interrupted in a circuit. The filter is not limited to materials having the above function, but can be made from various materials. For example, the form of the filter can be changed according to the design specifications.

[0086] The filter is made of, for example, a fibrous material. For example, the fibrous material may be a ceramic material such as SiO2, MgO, CaO, TiO2, Al2O3, or ZrO2, or an artificial mineral fiber (MMMF) made of SiO2, MgO, CaO, TiO2, Al2O3, or ZrO2, and from a safety standpoint, biosoluble fibers (biosoluble fiber: BSF, alkali earth silicate: AES), alumina fiber (polycrystalline fiber: PCW), glass wool, rock wool, slag wool, or silica fiber are particularly preferred. Alternatively, plastic materials such as nylon or PMMA can be used as the fibrous material. The form of the fibrous material is not limited to the above and can be changed according to the design specifications.

[0087] Furthermore, the filter is not limited to being made of fibrous material, but may be formed from a porous material. For example, the filter may be formed from a sheet-like material. For example, the filter may be ceramic fiber paper, or bio-soluble fiber paper, alumina fiber paper, glass wool paper, rock wool paper, slag wool paper, or silica fiber paper, and multiple sheets of ceramic fiber paper, or bio-soluble fiber paper, alumina fiber paper, glass wool paper, rock wool paper, slag wool paper, or silica fiber paper may be stacked and arranged in the internal pressure buffering space 61. For example, the filter is not limited to being paper, but may be in the shape of wool, a board, a block, etc. For example, the form of the filter can be changed according to the design specifications. Furthermore, the filler material 70 is not limited to those described above, and various materials can be used. The form of the filler material 70 can be changed according to the design specifications.

[0088] (Effects of this embodiment) The protective element 1 of this embodiment described above comprises a heating substrate 10 having an insulating substrate 11, a heating element 12 formed on the insulating substrate 11, a first connecting electrode 14 and a second connecting electrode 15 formed on the surface of the insulating substrate 11 and electrically connected to the heating element 12, and an end electrode 16 formed on the end face of the insulating substrate 11 and not electrically connected to the heating element 12; a first power supply member 21 connected to the first connecting electrode 14, a second power supply member 22 connected to the second connecting electrode 15, a fusible conductor 30 connected to the end electrode 16, a first terminal 41 and a second terminal 42 connected to both ends of the fusible conductor 30, and a case 50 that houses the heating substrate 10, the fusible conductor 30, a part of the first power supply member 21, at least a part of the second power supply member 22, a part of the first terminal 41, and a part of the second terminal 42. With this configuration, the end electrode 16, which is not electrically connected to the heating element 12, can be connected to the melting portion of the fusible conductor 30 at the end face of the insulating substrate 11. As a result, the length of the current-carrying direction of the connection surface between the heating substrate 10 and the fusible conductor 30 becomes extremely short. In other words, the conductive path due to the adhesion of molten material on the fusible conductor 30 becomes extremely short. This makes it possible to keep the electric field strength at the breakpoint of the fusible conductor 30 low and make it easier to stop arc discharge. Furthermore, it is not necessary to widen the width of the fusible conductor 30 in order to reduce the electrical resistance value of the protective element 1. Therefore, without increasing the size of the protective element 1, arc discharge can be stopped in a short time when interrupting overcurrents of 200V or more.

[0089] Although not shown in the diagram, conventional protective element configurations, for example, have the following problems (1) to (4). (1) When the heating substrate has a long and wide surface area in the direction of current flow, if a conductive path is formed on the wide surface of the heating substrate, the potential of this surface becomes approximately equal, and the applied voltage is applied to the narrow gap between the heating substrate and the external electrode. In this case, the electric field strength becomes very high, making it difficult to stop the arc discharge. In the configuration of Patent Document 1 (Japanese Patent No. 6364243), when the voltage exceeds 200V, it becomes difficult to stop the arc discharge early and to properly shut off the protective element. (2) In order to increase the voltage of the protective element, it is necessary to widen the gap between the heating substrate and the external electrode in order to keep the electric field strength of the fuse element's interrupting portion low. However, simply widening the gap will result in a longer fuse element. In this case, the electrical resistance value of the protective element will increase, and the rated current value will decrease. (3) The electrical resistance can be reduced by widening the fuse element. However, this increases the size of the protective element and thus the cost. (4) The electrical resistance can be reduced by increasing the thickness of the fuse element without changing its width. However, this tends to worsen the heating and melting characteristics of the fuse element due to its heat-generating component, increasing the quality risk. In contrast, according to this embodiment, all of the above-mentioned problems (1) to (4) can be solved with the configuration described above.

[0090] In this embodiment, the heating element 12 is formed on the surface of the insulating substrate 11. The first connecting electrode 14 and the second connecting electrode 15 are electrically connected to both ends of the heating element 12. The heating substrate 10 further has an insulating layer 13 laminated on the surface of the heating element 12. This configuration makes it possible to realize a heating substrate 10 in which the heating element 12 is formed on the surface of the insulating substrate 11.

[0091] In this embodiment, the case 50 has an internal pressure buffering space 61 which is connected to a leak area that overlaps with a portion of the fusible conductor 30 and has a larger volume than the leak area. With this configuration, the rapid increase in internal pressure of the protective element 1 caused by the gas generated by the arc discharge that occurs when the fusible conductor 30 is cut can be suppressed by the internal pressure buffer space 61. This prevents damage to the case 50, etc.

[0092] In this embodiment, the case 50 comprises a first case 51 and a second case 52 that sandwich the fusible conductor 30 from both sides in a direction perpendicular to the direction of current flow of the fusible conductor 30. Parts of the first case 51 and the second case 52 are in contact with or close to the fusible conductor 30. This configuration narrows the space formed between the first case 51 and a portion of the second case 52 and the fusible conductor 30. As a result, gas, which is one of the sources of arc discharge that occurs when overcurrent is interrupted, can be eliminated as much as possible around the fusible conductor 30. This suppresses the plasma generated by the ionization of gas, which is one of the sources of arc discharge, and thus suppresses arc discharge. In addition, it is not necessary to fill the area around the fusible conductor 30 with silica sand called an arc extinguishing agent to suppress arc discharge. Therefore, problems caused by the continuous adhesion of molten material to the surface of the arc extinguishing agent (problems such as a decrease in interruption characteristics or a decrease in insulation resistance after interruption) do not occur. Consequently, arc discharge during interruption is suppressed, high voltage and high current interruption is possible, and the decrease in insulation resistance after interruption can be suppressed.

[0093] In this embodiment, case 50 further comprises a third case 53 and a fourth case 54 that are placed over the combined body of the first case 51 and the second case 52 from both sides in a direction perpendicular to the joining direction of the combined body, thereby fixing the joined state of the first case 51 and the second case 52. With this configuration, by placing the third case 53 and fourth case 54 over the combined body of the first case 51 and the second case 52, the first case 51, the second case 52, the third case 53, and the fourth case 54 are maintained in a fixed state relative to each other. The orientation of a portion of the first terminal 41, a portion of the second terminal 42, the fusible conductor 30, and the heating substrate 10, which are positioned between the first case 51 and the second case 52, is stabilized. Furthermore, by placing the third case 53 and the fourth case 54 over the terminals 41, 42, the fusible conductor 30, the heating substrate 10, and the power supply members 21, 22 sandwiched between the first case 51 and the second case 52 from both terminal sides, the combined state of the first case 51 and the second case 52 can be fixed.

[0094] In this embodiment, the first case 51 and the second case 52 are made of a polyamide resin or a fluororesin. Resin materials have a lower heat capacity and melting point compared to, for example, ceramic materials. As in this embodiment, using polyamide resin or fluororesin as the material for the first case 51 and the second case 52 has the characteristic of weakening arc discharge due to gasification cooling (ablation). Furthermore, when molten and scattered metal particles adhere to the first case 51 and the second case 52, the surfaces of the first case 51 and the second case 52 deform or the attached material aggregates, resulting in sparse metal particles and making it difficult to form conduction paths, which is preferable. Furthermore, polyamide resins and fluororesins have high heat resistance and are difficult to burn. In particular, aliphatic polyamides do not easily form graphite even when burned. Therefore, by forming the first case 51 and the second case 52 with aliphatic polyamides, graphite formation due to arc discharge when the fusible conductor 30 is cut can be suppressed, and the formation of new current paths can be prevented more reliably.

[0095] Furthermore, in the protection element 1 of this embodiment, if an overcurrent exceeding the rated current (i.e., a current above a predetermined level) flows through the fusible conductor 30, the fusible conductor 30 heats up and melts, interrupting the current path. Alternatively, this protection element 1 can also interrupt the current path by passing current through the heating substrate 10 to generate heat, thereby melting and cutting the fusible conductor 30 superimposed on the end electrode 16. This suppresses the occurrence of a large-scale arc discharge when the fusible conductor 30 melts, and provides a protection element 1 that achieves both overcurrent interruption and interruption function by interruption signal (active interruption).

[0096] In this embodiment, a substrate housing space 63 for housing the heat-generating substrate 10 is formed in the case 50. With this configuration, the portion of the case 50 facing the fusible conductor 30, excluding the substrate housing space 63, can be positioned in closer contact with or near the fusible conductor 30. As a result, there is no longer a space between the fusible conductor 30 and the case 50 where arc discharge can continue, and arc discharge can be suppressed more reliably.

[0097] The present invention is not limited to the embodiments described above, and modifications to the configuration, etc., are possible without departing from the spirit of the invention, as described below. In the illustrations of modified examples, the same reference numerals are used for the same components as in the embodiments described above, and the main differences will be described below.

[0098] Figure 6A is a circuit diagram illustrating the effect of protection element 1. Figure 6B is another example of a circuit diagram of protection element 1. Referring also to Figure 6A, the protection element 1 includes a first terminal 41, a second terminal 42, a fusible conductor 30 whose ends are connected to the first terminal 41 and the second terminal 42 and which can be interrupted by an overcurrent flowing between the first terminal 41 and the second terminal 42, a third terminal 43, a fourth terminal 44, and a heating substrate 10 installed in the current path (heater circuit) between the third terminal 43 and the fourth terminal 44.

[0099] In this protection element 1, it is preferable that the current supply path CP1 (fuse circuit) via the fusible conductor 30 and the current supply path CP2 (heater circuit) via the heating substrate 10 are configured independently. In other words, the power supply for current supply path CP1 (fuse circuit) and the power supply for current supply path CP2 (heater circuit) are separate. This allows for the appropriate selection of the specifications of the heating substrate 10 in current supply path CP2. Therefore, even if a large voltage and large current are generated in current supply path CP1, sufficient withstand voltage can be ensured by lowering the voltage applied to the heating substrate 10 in current supply path CP2.

[0100] Furthermore, even if there is a large potential difference of, for example, 100V or more between the energizing path CP1 (fuse circuit) and the energizing path CP2 (heater circuit), the above-described configuration of this embodiment allows for a sufficiently large distance to be made, thereby suppressing interference in the area with a potential difference. In other words, the above-described heating substrate 10 can be arranged vertically (along the direction perpendicular to the direction of current flow of the fusible conductor (Z direction)). In this case, compared to the horizontal arrangement (along the direction of current flow of the fusible conductor, in other words, along the XY plane), the distance in the vertical direction (up and down direction) can be sufficiently large, thereby suppressing interference in the area with a potential difference.

[0101] The protective element 1 shown in Figure 6B includes a first terminal 41, a second terminal 42, a fusible conductor 30 whose ends are connected to the first terminal 41 and the second terminal 42 and which can be interrupted by an overcurrent flowing between the first terminal 41 and the second terminal 42, a third terminal 43, and a heating substrate 10 installed in the current path (heater circuit) between the third terminal 43 and the second terminal 42.

[0102] In this protection element 1, it is preferable that the current supply path CP1 (fuse circuit) passing through the fusible conductor 30 and the current supply path CP2 (heater circuit) passing through the heating substrate 10 are connected by the fusible conductor 30 or the second terminal 42. Although not shown, the second power supply member 22 and the end face electrode 16 may also be connected. This allows the power supply for the current supply path CP2 (heater circuit) to be supplied from at least a portion of the power supply for the current supply path CP1 (fuse circuit) (by supplying voltage from the middle of a series-connected lithium-ion battery cell). Therefore, a separate power supply for the current supply path CP2 (heater circuit) can be eliminated.

[0103] (Second Embodiment) A protective element 201 according to a second embodiment of the present invention will be described with reference to Figures 7 to 10. The protective element 201 of the second embodiment differs from the first embodiment described above mainly in that the heating substrate 210 is equipped with an inlet electrode 217. In the figures of this embodiment, components that are the same as or substantially the same as those of the first embodiment may be given the same reference numerals or names and their descriptions may be omitted.

[0104] Referring also to Figures 7 to 9, the heating substrate 210 further comprises a pull-in electrode 217 formed on the front and / or back surface of the insulating substrate 11, connected to the end electrode 16, and not electrically connected to the heating element 12.

[0105] In the example shown in the figure, the lead-in electrode 217 is formed on both the front and back surfaces of the insulating substrate 11. However, the lead-in electrode 217 may also be formed only on the front surface of the insulating substrate 11, or only on the back surface of the insulating substrate 11. The formation method of the lead-in electrode 217 can be changed according to the design specifications.

[0106] The front-side inlet electrode 217 is connected to the front end of the end-face electrode 16. The rear-side inlet electrode 217 is connected to the rear end of the end-face electrode 16. The inlet electrode 217 is electrically insulated from the heating element 12, the first connecting electrode 14, and the second connecting electrode 15 on the front side of the insulating substrate 11. When viewed from the front side of the insulating substrate 11, the upper edge of the front-side inlet electrode 217 is positioned below the lower edge of the heating element 12.

[0107] In the example shown, the lead electrode 217 has a rectangular shape, with its left-right dimension being larger than its vertical dimension. In the example shown, the lead electrode 217 has a vertical dimension greater than the thickness (vertical dimension) of the end electrode 16, and the same left-right dimension as the insulating substrate 11. The front lead electrode 217 and the rear lead electrode 217 have the same vertical and left-right dimensions. Note that the shape of the lead electrode 217 is not limited to the above and can be changed according to the design specifications.

[0108] In the protective element 201 of this embodiment described above, the heating substrate 10 further comprises an inducting electrode 217 formed on the front and / or back surface of the insulating substrate 11, connected to the end electrode 16, and not electrically connected to the heating element 12. This configuration allows the lead electrode 217 to hold more of the molten fusible conductor 30, thereby improving the cutting characteristics. In this embodiment, since the lead electrode 217 is formed on both the front and back surfaces of the insulating substrate 11, the molten fusible conductor 30 can be held by the lead electrodes 217 on both sides, as shown in Figure 10.

[0109] (Third embodiment) A protective element 301 according to the third embodiment of the present invention will be described with reference to Figures 11 to 14. The protective element 301 of the third embodiment differs from the first embodiment described above mainly in that a heating element 312 is formed inside the insulating substrate 311. In the figures of this embodiment, components that are the same as or substantially the same as those of the first embodiment may be given the same reference numerals or names and their descriptions may be omitted.

[0110] Referring together to Figures 11 to 13, the heating substrate 310 includes an insulating substrate 311, a heating element 312 formed inside the insulating substrate 311, a first connecting electrode 314 and a second connecting electrode 315 formed on the surface of the insulating substrate 311 and electrically connected to the heating element 312, and an end electrode 316 formed on the end face of the insulating substrate 311 and not electrically connected to the heating element 312.

[0111] The insulating substrate 311 has first through-holes 318 and second through-holes 319 formed on it, connecting from both ends of the heating element 312 to the surface of the insulating substrate 311. The first connecting electrode 314 is electrically connected to the heating element 312 via the first through-hole 318. The second connecting electrode 315 is electrically connected to the heating element 312 via the second through-hole 319.

[0112] The insulating substrate 311 is an insulating substrate such as alumina, glass ceramics, mullite, or zirconia. However, the material of the insulating substrate 311 is not limited to those mentioned above and can be changed according to the design specifications.

[0113] The insulating substrate 311 has a rectangular shape that is larger than the heating element 312 when viewed from the front-to-back direction. In the example shown in the figure, the insulating substrate 311 has a rectangular shape in which the left-to-right dimension is larger than the up-to-down dimension. Specifically, the insulating substrate 311 has thickness in the direction parallel to the direction of current flow through the fuse element (generally the front-to-back direction), extends in the direction intersecting the direction of current flow, and in the example shown in the figure, has its longitudinal side in the direction perpendicular to the direction of current flow (left-to-right direction). Note that the shape of the insulating substrate 311 is not limited to the above and can be changed according to the design specifications.

[0114] The heating element 312 is made of a conductive material that generates heat when an electric current is applied, such as W, Mo, Ru, or a material containing these. Preferably, the heating element 312 is made of a high-melting-point metal having a melting point of 1700°C or higher. The heating element 312 can be formed by placing powdered alloys, compositions, or compounds of these materials inside the insulating substrate 311 and firing (sintering) it. The material of the heating element 312 is not limited to the above and can be changed according to the design specifications.

[0115] In the example shown in the figure, the heating element 312 is formed to include a meander shape when viewed from the front-to-back direction. The heating element 312 is formed to include a meandering portion that meanders vertically. In the example shown in the figure, the heating element 312 extends downward from the portion overlapping with the first through-hole 318, then bends and extends to the right, then bends and extends upward, then bends again and extends to the right, then bends further and extends downward, repeating this process multiple times, and finally bends and extends upward to reach the portion overlapping with the second through-hole 319. Note that the shape of the heating element 312 is not limited to the above and can be changed according to the design specifications.

[0116] In the example shown in the figure, the heating element 312 is positioned within the insulating substrate 311, slightly below the vertical center and towards the front-to-back center. When viewed from the front-to-back direction, the heating element 312 is positioned such that the distance between it and the lower edge of the insulating substrate 311 is narrower than the distance between it and the upper edge of the insulating substrate 311, and the distances between it and the left and right edges of the insulating substrate 311 are equal. Note that the arrangement of the heating element 312 is not limited to the above and can be changed according to the design specifications.

[0117] The first through-hole 318 and the second through-hole 319 open in the front-to-back direction from the front side of the insulating substrate 311 to the interior of the insulating substrate 311. In the example shown in the figure, the first through-hole 318 and the second through-hole 319 form a circular shape when viewed from the front side of the insulating substrate 311. Note that the shape of the first through-hole 318 and the second through-hole 319 is not limited to the above and can be changed according to the design specifications.

[0118] The first connecting electrode 314 is electrically connected to the heating element 312 via the first through-hole 318. The second connecting electrode 315 is electrically connected to the heating element 312 via the second through-hole 319. The first connecting electrode 314 and the second connecting electrode 315 have a rectangular portion located on the upper end of the insulating substrate 311 when viewed from the front side of the insulating substrate 311, and a portion extending downward from the lower end of this portion and connected to the heating element 312. Note that the shapes of the first connecting electrode 314 and the second connecting electrode 315 are not limited to those described above and can be changed according to the design specifications.

[0119] The end electrode 316 is formed on the lower end surface of the insulating substrate 311. The end electrode 316 is electrically insulated from the heating element 312, the first connecting electrode 314, and the second connecting electrode 315 inside the insulating substrate 311. In the example shown in the figure, the end electrode 316 has a rectangular shape in which the left-right dimension is larger than the front-back dimension. In the example shown in the figure, the front-back dimension of the end electrode 316 is the same as the thickness (front-back dimension) of the insulating substrate 311, and it has the same left-right dimension as the insulating substrate 311. Note that the shape of the end electrode 316 is not limited to the above and can be changed according to the design specifications.

[0120] In this embodiment, the heating element 312 is formed inside the insulating substrate 311. The insulating substrate 311 has first through-holes 318 and second through-holes 319 that connect from both ends of the heating element 312 to the surface of the insulating substrate 311. The first connecting electrode 314 is electrically connected to the heating element 312 via the first through-hole 318. The second connecting electrode 315 is electrically connected to the heating element 312 via the second through-hole 319. This configuration makes it possible to realize a heating substrate 310 in which the heating element 312 is formed inside the insulating substrate 311. In this embodiment, since the end face electrode 316 is formed on the lower end surface of the insulating substrate 311, the molten material of the fusible conductor 30 can be held by the end face electrode 316, as shown in Figure 14.

[0121] (Fourth Embodiment) A protective element 401 according to the fourth embodiment of the present invention will be described with reference to Figures 15 to 18. The protective element 401 of the fourth embodiment differs from the third embodiment described above mainly in that the heating substrate 410 is equipped with an inlet electrode 417. In the figures of this embodiment, components that are the same as or substantially the same as those in the third embodiment may be given the same reference numerals or names and their descriptions may be omitted.

[0122] Referring together to Figures 15 to 17, the heating substrate 410 further comprises a pull-in electrode 417 formed on the front and / or back surface of the insulating substrate 311, connected to the end electrode 316, and not electrically connected to the heating element 312.

[0123] In the example shown in the figure, the lead-in electrode 417 is formed on both the front and back surfaces of the insulating substrate 311. Alternatively, the lead-in electrode 417 may be formed only on the front surface of the insulating substrate 311, or only on the back surface. The configuration of the lead-in electrode 417 can be changed according to the design specifications.

[0124] The front-side inlet electrode 417 is connected to the front end of the end-face electrode 316. The rear-side inlet electrode 417 is connected to the rear end of the end-face electrode 316. The inlet electrode 417 is electrically insulated from the heating element 312 inside the insulating substrate 311, and from the first connecting electrode 314 and the second connecting electrode 315 on the front side of the insulating substrate 311. When viewed from the front-rear direction, the upper edge of the inlet electrode 417 is positioned above the lower edge of the heating element 312.

[0125] In the example shown in the figure, the lead electrode 417 has a rectangular shape, with its left-right dimension being larger than its vertical dimension. In the example shown in the figure, the lead electrode 417 has a vertical dimension greater than the thickness (vertical dimension) of the end electrode 16, and the same left-right dimension as the insulating substrate 311. The front lead electrode 417 and the rear lead electrode 417 have the same vertical and left-right dimensions. Note that the shape of the lead electrode 417 is not limited to the above and can be changed according to the design specifications.

[0126] In the protective element 401 of this embodiment described above, the heating substrate 410 further comprises an inlet electrode 417 formed on the front and / or back surface of the insulating substrate 311, connected to the end electrode 316, and not electrically connected to the heating element 312. This configuration allows the lead electrode 417 to hold more of the molten fusible conductor 30, thereby improving the cutting characteristics. In this embodiment, since the lead electrode 417 is formed on both the front and back surfaces of the insulating substrate 311, the molten fusible conductor 30 can be held by the lead electrodes 417 on both sides, as shown in Figure 18.

[0127] (Fifth embodiment) A protective element 501 according to the fifth embodiment of the present invention will be described with reference to Figure 19. The protective element 501 of the fifth embodiment differs from the first embodiment described above mainly in that it has a first conductor 531 and a second conductor 532 connected to both ends of the fusible conductor 530. In the figures of this embodiment, components that are the same as or substantially the same as those of the first embodiment may be given the same reference numerals or names and their descriptions may be omitted.

[0128] As shown in Figure 19, the protective element 501 has a first conductor 531 and a second conductor 532 connected to both ends of the fusible conductor 530 in the front-rear direction. Each of the first conductor 531 and the second conductor 532 is plate-shaped, sheet-shaped, or foil-shaped. In this embodiment, each of the first conductor 531 and the second conductor 532 is a metal plate-shaped member. For example, each of the first conductor 531 and the second conductor 532 has a substantially rectangular plate shape, with the left-right dimension being shorter than the front-rear dimension when viewed from above. For example, each of the first conductor 531 and the second conductor 532 is made of Ag or Cu, or a metal mainly composed of Ag or Cu. When copper is used, it is preferable to apply a rust-preventive treatment such as nickel plating, silver plating, or tin plating to the surface.

[0129] The first conductor 531, the fusible conductor 530, and the second conductor 532 are connected in series in this order to form the current path of the fuse element. The first conductor 531 is connected to the first terminal 41. The second conductor 532 is connected to the second terminal 42. The melting temperature of the fusible conductor 530 is lower than the melting temperatures of the first conductor 531 and the second conductor 532.

[0130] The fusible conductor 530 functions as the melting portion of the fuse element during both overcurrent interruption and active interruption. For example, it is preferable that the fusible conductor 530 is made of a material with a lower melting temperature than each of the first conductor 531 and the second conductor 532. For example, it is preferable that the fusible conductor 530 has a higher electrical resistivity than each of the first conductor 531 and the second conductor 532.

[0131] The front end of the first conductor 531 is connected to the rear end of the first terminal 41, for example, by soldering or welding. In the example shown in the figure, the rear end of the first terminal 41 is fixed on the front end of the first conductor 531. That is, the lower surface of the rear end of the first terminal 41 and the upper surface of the front end of the first conductor 531 are connected to each other. The rear end of the first conductor 531 is connected to the front end of the fusible conductor 530, for example, by soldering or welding. In the example shown in the figure, the front end of the fusible conductor 530 is fixed onto the rear end of the first conductor 531. That is, the upper surface of the rear end of the first conductor 531 and the lower surface of the front end of the fusible conductor 530 are connected to each other.

[0132] The front end of the second conductor 532 is connected to the rear end of the fusible conductor 530, for example, by soldering or welding. In the example shown in the figure, the rear end of the fusible conductor 530 is fixed onto the front end of the second conductor 532. That is, the upper surface of the front end of the second conductor 532 and the lower surface of the rear end of the fusible conductor 530 are connected to each other. The rear end of the second conductor 532 is connected to the front end of the second terminal 42, for example, by soldering or welding. In the example shown in the figure, the front end of the second terminal 42 is fixed on the rear end of the second conductor 532. That is, the lower surface of the front end of the second terminal 42 and the upper surface of the rear end of the second conductor 532 are connected to each other.

[0133] The fusible conductor 530 is positioned on the upper surfaces of the first conductor 531 and the second conductor 532 and spans between them. The vertical relationship of the connections between the fusible conductor 530 and the first conductor 531 and the second conductor 532 is not limited to the above. For example, the fusible conductor 530 may be placed on the lower side of the first conductor 531 and the second conductor 532. Furthermore, the hierarchical relationship between the connection of the first conductor 531 and the first terminal 41, and the hierarchical relationship between the connection of the second conductor 531 and the second terminal 42 are not limited to those described above. For example, the first conductor 531 may be positioned on the upper side of the first terminal 41. For example, the second conductor 532 may be positioned on the upper side of the second terminal 42.

[0134] According to the configuration of this embodiment, the end electrode 16, which is not electrically connected to the heating element 12, can be connected to the melting portion of the fusible conductor 530 at the end face of the insulating substrate 11. As a result, the length of the current-carrying direction of the connection surface between the heating substrate 10 and the fusible conductor 530 becomes extremely short. In other words, the conductive path due to the adhesion of molten material to the fusible conductor 530 becomes extremely short. This makes it possible to keep the electric field strength at the breakpoint of the fusible conductor 530 low and make it easier to stop arc discharge. Furthermore, it is not necessary to widen the width of the fusible conductor 530 in order to reduce the electrical resistance value of the protective element 501. Therefore, without increasing the size of the protective element 501, arc discharge can be stopped in a short time when interrupting overcurrents of 200V or more.

[0135] (Sixth Embodiment) A protective element 601 according to the sixth embodiment of the present invention will be described with reference to Figure 20. The protective element 601 of the sixth embodiment differs from the fifth embodiment mainly in the connection relationship between the first conductor 631 and the second conductor 632 to both ends of the fusible conductor 630. In the figures of this embodiment, components that are the same as or substantially the same as those of the fifth embodiment may be given the same reference numerals or names and their descriptions may be omitted.

[0136] As shown in Figure 20, the protective element 601 has a first conductor 631 and a second conductor 632 connected to both ends of the fusible conductor 630 in the front-rear direction. The first conductor 631, the fusible conductor 630, and the second conductor 632 are connected in series in this order to form the current path of the fuse element. The first conductor 631 is connected to the first terminal 41. The second conductor 632 is connected to the second terminal 42. The melting temperature of the fusible conductor 630 is lower than the melting temperatures of the first conductor 631 and the second conductor 632.

[0137] The rear end of the first conductor 631 is connected to the front end of the fusible conductor 630, for example, by soldering or welding. In the example shown in the figure, the front end surface of the fusible conductor 630 is fixed to the rear end surface of the first conductor 631. That is, the first conductor 631 and the fusible conductor 630 are connected to each other at their opposing end surfaces in the front-to-back direction.

[0138] The front end of the second conductor 632 is connected to the rear end of the fusible conductor 630, for example, by soldering or welding. In the example shown in the figure, the rear end surface of the fusible conductor 630 is fixed to the front end surface of the second conductor 632. That is, the second conductor 632 and the fusible conductor 630 are connected to each other at their opposing end surfaces in the front-rear direction.

[0139] According to the configuration of this embodiment, the end electrode 16, which is not electrically connected to the heating element 12, can be connected to the melting portion of the fusible conductor 630 at the end face of the insulating substrate 11. As a result, the length of the current-carrying direction of the connection surface between the heating substrate 10 and the fusible conductor 630 becomes extremely short. In other words, the conductive path due to the adhesion of molten material to the fusible conductor 630 becomes extremely short. This makes it possible to keep the electric field strength at the breakpoint of the fusible conductor 630 low and make it easier to stop arc discharge. Furthermore, it is not necessary to widen the width of the fusible conductor 630 in order to reduce the electrical resistance value of the protective element 601. Therefore, without increasing the size of the protective element 601, arc discharge can be stopped in a short time when interrupting overcurrents of 200V or more.

[0140] (modified version) In the above embodiment, an example was given in which the case is connected to a leak area that overlaps with a portion of the fusible conductor, and an internal pressure buffer space with a larger volume than the leak area is formed; however, the invention is not limited to this example. For example, an internal pressure buffer space may not be formed in the case. The manner in which the internal pressure buffer space is formed can be changed according to the design specifications.

[0141] In the above embodiment, the case comprises a first case and a second case that sandwich the fusible conductor from both sides in a direction perpendicular to the direction of current flow of the fusible conductor, and a part of the first case and the second case is in contact with or close to the fusible conductor. However, the embodiment is not limited to this example. For example, an insulating member may be provided between the first case and the second case, and the inside of the insulating member may be in contact with or close to the fusible conductor. For example, a part of the first case and the second case may not be in contact with or close to the fusible conductor. The configuration of the first case and the second case (the configuration in which they are in contact with or close to the fusible conductor) can be changed according to the design specifications.

[0142] In the above embodiment, the case was described as further comprising a third case and a fourth case that are placed over the combined body of the first and second cases from both sides in a direction perpendicular to the joining direction of the combined body to fix the joined state of the first and second cases, but it is not limited to this. For example, the third case and the fourth case may be placed over the combined body of the first and second cases from both sides in a direction parallel to the joining direction of the combined body. The installation method of the third case and the fourth case can be changed according to the design specifications.

[0143] In the embodiments described above, the first and second cases were explained using examples of polyamide resin or fluororesin. However, they are not limited to these. For example, the first and second cases may be formed from materials other than polyamide resin and fluororesin. The formation methods of the first and second cases can be changed according to the design specifications.

[0144] In the above embodiment, the fusible conductor was described as a laminate containing a high-melting-point metal layer and a low-melting-point metal layer, but it is not limited to this. For example, the fusible conductor may be composed of a single layer of the high-melting-point metal layer. For example, the fusible conductor may be composed of a single layer of the low-melting-point metal layer. The configuration of the fusible conductor can be changed according to the design specifications.

[0145] The present invention may be combined in any way that does not depart from the spirit of the invention, as described in the above embodiments and modifications, and the configurations may be added, omitted, substituted, or otherwise modified. Furthermore, the present invention is not limited by the above embodiments, but is limited only by the claims. [Explanation of symbols]

[0146] 1, 201, 301, 401, 501, 601… Protective elements 10,210,310,410…Heating substrate 11,311…Insulating substrate 12,312…heating element 13…Insulating layer 14,314…First connecting electrode 15,315...Second connecting electrode 16...End electrode 21...First power supply member 22...Second power supply component 30, 530, 630… Fusible conductors 41...1st terminal 42…Second terminal 50...cases 51…Case 1 52…Case 2 53…Case 3 54…Case 4 61...Internal pressure buffering space 217,417…Incoming electrode 316...End electrode 318…First through hole 319...Second through hole 531,631…First conductor 532,632…Second conductor

Claims

1. Insulating substrate and A heating element formed on the insulating substrate, A first connecting electrode and a second connecting electrode are formed on the surface of the insulating substrate and are electrically connected to the heating element, A heating substrate having an end electrode formed on the end face of the insulating substrate and not electrically connected to the heating element, A first power supply member connected to the first connecting electrode, and a second power supply member connected to the second connecting electrode, A fusible conductor connected to the end face electrode, The first terminal and the second terminal connected to both ends of the fusible conductor, The device comprises the heating substrate, the fusible conductor, a part of the first power supply member, at least a part of the second power supply member, a part of the first terminal, and a case that houses the second terminal. Protective element.

2. The heating element is formed on the surface of the insulating substrate, The first connecting electrode and the second connecting electrode are electrically connected to both ends of the heating element. The heating substrate further comprises an insulating layer laminated on the surface of the heating element. The protective element according to claim 1.

3. The heating element is formed inside the insulating substrate, The insulating substrate has first through-holes and second through-holes formed therein, connecting both ends of the heating element to the surface of the insulating substrate. The first connecting electrode is electrically connected to the heating element via the first through-hole. The second connecting electrode is electrically connected to the heating element via the second through-hole. The protective element according to claim 1.

4. In the aforementioned case, an internal pressure buffer space is formed that is connected to a leak area that overlaps with a portion of the fusible conductor, and has a larger volume than the leak area. A protective element according to any one of claims 1 to 3.

5. The case comprises a first case and a second case that sandwich the fusible conductor from both sides in a direction perpendicular to the direction of current flow of the fusible conductor, Parts of the first case and the second case are in contact with or close to the fusible conductor. A protective element according to any one of claims 1 to 3.

6. The case further comprises a third case and a fourth case that are placed over the combined body of the first case and the second case from both sides in a direction perpendicular to the joining direction of the combined body, thereby fixing the joined state of the first case and the second case. The protective element according to claim 5.

7. The first case and the second case are made of polyamide resin or fluororesin. The protective element according to claim 5.

8. The fusible conductor is a laminate comprising a high-melting-point metal layer and a low-melting-point metal layer. A protective element according to any one of claims 1 to 3.

9. The aforementioned high-melting-point metal layer is made of Ag or Cu, or a metal mainly composed of Ag or Cu. The low-melting-point metal layer is made of Sn or a metal mainly composed of Sn. The protective element according to claim 8.

10. The heating substrate further comprises a pull-in electrode formed on the surface and / or back surface of the insulating substrate, connected to the end face electrode, and not electrically connected to the heating element. A protective element according to any one of claims 1 to 3.

11. The fusible conductor has a first conductor and a second conductor connected to both ends thereof, The first conductor is connected to the first terminal, The second conductor is connected to the second terminal, The melting temperature of the fusible conductor is lower than the melting temperatures of the first and second conductors. A protective element according to any one of claims 1 to 3.

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