Patent ID: 12261007

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments will be described in detail with reference to drawings as appropriate. In the drawings used in the following description, characteristic parts may be illustrated in an enlarged manner for convenience to facilitate an understanding thereof, and the dimensional ratio and the like of each constituent element may differ in practice. The materials, dimensions, and the like exemplified in the following description are examples; the present invention is not limited thereto, and can be implemented with appropriate changes within a scope wherein the effect of the present invention is exhibited.

First Embodiment

(Protection Element)

FIGS.1to11are pattern diagrams illustrating a protection element of a first embodiment. In the drawings used in the following description, the direction indicated by an X is an energizing direction (first direction) of a fuse element. The direction indicated by a Y is a direction orthogonal to the X-direction (first direction), and the direction indicated by a Z is a direction orthogonal to the X-direction and the Y-direction.

FIG.1is a perspective view illustrating an entire structure of a protection element100of the first embodiment.FIG.2is an exploded perspective view illustrating the entire structure of the protection element100illustrated inFIG.1.FIG.3is a cross-section view of the protection element100of the first embodiment, cut along line A-A′ illustrated inFIG.1.FIG.4is an enlarged cross-section view illustrating one portion ofFIG.3in an enlarged manner.FIG.5is a drawing for describing the operation of the protection element100of the first embodiment, and is a cross-section view thereof cut along line A-A′ illustrated inFIG.1.FIG.6is an enlarged cross-section view illustrating one portion ofFIG.5in an enlarged manner.

The protection element100of the present embodiment, as illustrated inFIG.1toFIG.3, is provided with a fuse element2, a shielding member3, a case6provided internally with a housing portion60wherein the fuse element2and the shielding member3are stored, and a cover4covering a side surface of the case6in the Y-direction and the Z-direction.

In the protection element100of the present embodiment, pressure elevation in the housing portion60due to an arc discharge generated when the fuse element2fuses causes, as illustrated inFIG.5andFIG.6, the shielding member3to rotate around a rotation axis33, and the shielding member3divides the inside of the housing portion60.

(Fuse Element)

FIG.7is an enlarged drawing for describing one portion of the protection element100of the first embodiment, and is a perspective view illustrating the fuse element, a first terminal, and a second terminal.

As illustrated inFIG.7, the fuse element2is belt-shaped, and has a first end portion21, a second end portion22, and a cut portion23composed of a constricted portion provided between the first end portion21and the second end portion22. The fuse element2is energized in the X-direction (first direction) from the first end portion21to the second end portion22.

As illustrated inFIG.3andFIG.7, the first end portion21is electrically connected to the first terminal61. The second end portion22is electrically connected to the second terminal62.

The first terminal61and the second terminal62, as illustrated inFIG.7, may be substantially the same shape or may each be different shapes. A thickness of the first terminal61and the second terminal62is not particularly limited, but as a guideline, it may be set to 0.3 to 1.0 mm. The thickness of the first terminal61and the thickness of the second terminal62, as illustrated inFIG.3, may be the same or may be different.

As illustrated inFIG.1toFIG.3andFIG.7, the first terminal61is provided with an external terminal hole61a. Furthermore, the second terminal62is provided with an external terminal hole62a. One from among the external terminal hole61aand the external terminal hole62ais used to connect to a power supply side, and the other is used to connect to a load side. The external terminal hole61aand the external terminal hole62a, as illustrated inFIG.7, may be through holes that are substantially circular in a plan view.

A material composed of, for example, copper, brass, nickel, or the like may be used as the first terminal61and the second terminal62. From the perspective of strengthening rigidity, it is preferable to use brass as a material of the first terminal61and the second terminal62, and from the perspective of reducing electrical resistance, it is preferable to use copper. The first terminal61and the second terminal62may be composed of the same material or may be composed of different materials.

The shape of the first terminal61and the second terminal62may be any, provided that it is capable of engaging with a terminal on the power supply side or a terminal on the load side (not illustrated); for example, it may be a claw shape having a partially open portion, and as illustrated inFIG.7, it may have a flange portion (indicated by reference signs61c,62cinFIG.7) at an end portion of a side connected to the fuse element2, widened on both sides towards the fuse element2—the shape is not particularly limited. When the first terminal61and the second terminal62have the flange portion61c,62c, it is difficult for the first terminal61and the second terminal62to come out of the case6, resulting in the protection element100having good reliability and durability.

The fuse element2illustrated inFIG.7has a substantially uniform thickness (length in the Z-direction). The thickness of the fuse element2, as illustrated inFIG.3, may be uniform or may be partially different. A fuse element having a thickness that gradually increases from the cut portion23to the first end portion21and the second end portion22is given as an example of a fuse element having a partially different thickness. In this kind of fuse element, the cut portion23becomes a heatspot when an overcurrent flows, so the cut portion23is preferentially heated and softened to ensure it is cut more reliably.

The thickness of the fuse element2may be set to, example, 0.03 to 1.0 mm, and preferably, may be set to 0.2 to 0.5 mm.

As illustrated inFIG.7, the fuse element2has a substantially rectangular shape in a plan view. As illustrated inFIG.7, a width21D of the first end portion21in the Y-direction and a width22D of the second end portion22in the Y-direction are substantially the same. Accordingly, the width of the fuse element2in the Y-direction illustrated inFIG.7means the widths21D and22D of the first end portion21and the second end portion22in the Y-direction.

As illustrated inFIG.1,FIG.3, andFIG.7, the first end portion21of the fuse element2is disposed to overlap the first terminal61in a plan view. Furthermore, the second end portion22of the fuse element2is disposed to overlap the second terminal62in a plan view.

As illustrated inFIG.7, a length of the first end portion21in the X-direction extends from a region overlapping the first terminal61in a plan view toward a side of the cut portion23. Furthermore, as illustrated inFIG.7, a length of the second end portion22in the X-direction extends from a region overlapping the second terminal62in a plan view toward a side of the cut portion23. In the fuse element2illustrated inFIG.7, the length of the second end portion22in the X-direction and the length of the first end portion21in the X-direction are substantially the same. In other words, in the present embodiment, the cut portion23is disposed around the center of the fuse element2in the X-direction.

As illustrated inFIG.7, a first connecting unit25having a substantially trapezoidal shape in a plan view is disposed between the cut portion23and the first end portion21. A longer parallel side of the first connecting unit25having a substantially trapezoidal shape in a plan view is coupled to the first end portion21. Furthermore, a second connecting unit26having a substantially trapezoidal shape in a plan view is disposed between the cut portion23and the second end portion22. A longer parallel side of the second connecting unit26having a substantially trapezoidal shape in a plan view is coupled to the second end portion22. The first connecting unit25and the second connecting unit26are symmetrical with respect to the cut portion23. As a result, the width of the fuse element2in the Y-direction gradually widens from the cut portion23to the first end portion21and the second end portion22. As a result, the cut portion23becomes a heatspot when an overcurrent flows to the fuse element, so the cut portion23is preferentially heated and softened to ensure it is cut or fused easily.

As illustrated inFIG.7, a width23D of the cut portion23of the fuse element2in the Y-direction is narrower than the widths21D and22D of the first end portion21and the second end portion22in the Y-direction. As a result, a cross-sectional area of the cut portion23in the Y-direction is narrower than a cross-sectional area of a region of the fuse element2other than the cut portion23. Therefore, the cut portion23is cut or fused more easily than a region between the cut portion23and the first end portion21, and a region between the cut portion23and the second end portion22.

In the present embodiment, as illustrated inFIG.7, a fuse element having the cut portion23composed of a constricted portion having a narrower width23D in the Y-direction than the widths21D and22D of the first end portion21and the second end portion22in the Y-direction is described as an example of the fuse element2; however, the fuse element may have a cut portion having a width in the Y-direction that is the same as the first end portion and the second end portion, and it is not limited to the case where the fuse element may have a cut portion having a width in the Y-direction that is narrower than the first end portion and the second end portion.

For example, it is also possible to provide a line-shaped or belt-shaped fuse element having a uniform cross-sectional area in the Y-direction in place of the fuse element2illustrated inFIG.7. In this case, the cross-sectional area of the cut portion of the fuse element in the Y-direction (second direction) is the same as the cross-sectional area of a region of the fuse element other than the cut portion.

As illustrated inFIG.3andFIG.7, the fuse element2has two bent portions composed of a first bent portion24aand a second bent portion24bwherein a belt-shaped member is bent twice at a substantial right angle along the Y-direction. The first bent portion24ais a step formed so as to cover an end surface of the first terminal61along an edge portion of a region where the first end portion21and the first terminal61overlap in a plan view. The second bent portion24bis a step formed so as to cover an end surface of the second terminal62along an edge portion of a region where the second end portion22and the second terminal62overlap in a plan view. The first bent portion24aand the second bent portion24balleviate stress associated with thermal expansion and contraction due to heat in the fuse element2extending in the X-direction, thereby improving the durability of the fuse element2.

In the present embodiment, as illustrated inFIG.3, since the fuse element2has the first bent portion24aand the second bent portion24b, a surface of a side whereon the first end portion21of the first terminal61is not laminated, a surface of a side whereon the second end portion22of the second terminal62is not laminated, and one surface at a center portion of the fuse element2(surface of a lower side inFIG.3) are disposed on substantially the same plane.

In the present embodiment, as illustrated inFIG.7, the first bent portion24aand the second bent portion24bwherein a belt-shaped member is bent along the Y-direction are described as examples of the bent portion; however, the direction in which a belt-shaped material forming the bent portion is bent is not limited to the Y-direction—it may be any, provided that it is bent intersecting the X-direction.

Furthermore, in the present embodiment, the first bent portion24aand the second bent portion24bwherein a belt-shaped member is bent twice at a substantial right angle is described as an example of the bent portion; however, the angle at which and the number of times the belt-shaped material forming the bent portion is bent are not particularly limited.

Furthermore, in the present embodiment, a case where the first bent portion24ais provided on a side of the first end portion21of the fuse element2, and the second bent portion24bis provided on a side of the second end portion22is described as an example; however, the number of bent portions provided in the fuse element may be one or may be three or more, and the bent portion need not be provided in the fuse element.

A known material used for a fuse element, such as a metal material including an alloy, may be used as a material of the fuse element2. Specifically, an alloy such as Pb85%/Sn, Sn/Ag3%/Cu0.5%, or the like may be exemplified as a material of the fuse element2.

It is preferable that the fuse element2is composed of a laminated body wherein an inner layer composed of a low-melting-point metal and an outer layer composed of a high-melting-point metal are laminated in a thickness direction. This kind of fuse element2is preferable because it has good solderability when soldering the first terminal61and the second terminal62to the fuse element2.

When the fuse element2is composed of the laminated body wherein the inner layer composed of the low-melting-point metal and the outer layer composed of the high-melting-point layer are laminated in the thickness direction, it is preferable that the volume of the low-melting-point metal is larger than the volume of the high-melting-point metal in terms of the current interrupting characteristic of the fuse element2.

It is preferable to use Sn or a metal having Sn as a main component as the low-melting-point metal used as a material of the fuse element2. Since the melting point of Sn is 232° C., a metal having Sn as a main component has a low melting point and becomes soft at low temperatures. For example, the solidus line of Sn/Ag3%/Cu0.5% alloy is 217° C.

Here, it is preferable that the low melting point is within a range of 120° C. to 260° C. Furthermore, “main component” refers to 50 mass % or more of the component contained.

It is preferable to use Ag or Cu, or a metal having Ag or Cu as a main component as the high-melting-point metal used as a material of the fuse element2. For example, since the melting point of Ag is 962° C., a layer composed of a metal having Ag as a main component maintains rigidity at a temperature whereat the layer composed of a low-melting-point metal softens.

Furthermore, this is preferable as when a metal having Ag as a main component is formed as an outer layer, a resistance value of the fuse element2may be efficiently lowered and a rated current of the protection element may be set high. Here, it is preferable that the high melting point be within a range of 800° C. to 1,200° C. Furthermore, “main component” refers to 90 mass % or more of the component contained.

When the fuse element2is composed of the laminated body wherein the inner layer composed of the low-melting-point metal and the outer layer composed of the high-melting-point metal are laminated in the thickness direction, and has the cut portion23composed of a constricted portion having the narrower width23D in the Y-direction than the widths21D and22D of the first end portion21and the second end portion22in the Y-direction, the outer layer may be formed on a side surface of the cut portion23in the Y-direction, or the outer layer need not be formed.

A melting temperature of the fuse element2in the protection element100of the present embodiment is preferably equal to or less than 600° C., and more preferably equal to or less than 400° C. When the melting temperature is equal to or less than 600° C., an arc discharge generated when the fuse element2fuses is further reduced.

Only one sheet may be used for the fuse element2, or a plurality of sheets may be laminated and used as necessary. In the present embodiment, a case where two sheets are laminated and used is described as an example of the fuse element2; however, only one sheet may be used, or three or more laminated sheets may be used.

The fuse element2may be manufactured by a known method.

For example, when composed of the laminated body wherein the inner layer composed of the low-melting-point metal and the outer layer composed of the high-melting-point metal are laminated in the thickness direction, and the outer layer is not formed in the Y-direction on a side surface of the cut portion23composed of a constricted portion, the fuse element2may be manufactured by the method shown below. First, a metal foil composed of the low-melting-point metal is prepared. Next, the high-melting-point metal layer is formed on an entire surface of the metal foil using plating to form a laminate. Thereafter, the laminate is cut to form a predetermined shape having the cut portion23composed of a constricted portion. The fuse element2composed of a laminated body having a three-layer structure is obtained by the above process.

When manufacturing a material composed of the foregoing laminated body, having the cut portion23composed of a constricted portion, and having the outer layer formed on a side surface of the cut portion23in the Y-direction, the fuse element2may be manufactured by the method shown below. That is, a metal foil composed of the low-melting-point metal is prepared, and the metal foil is cut to form a predetermined shape. Next, the high-melting-point metal layer is formed on an entire surface of the metal foil using plating to form a laminate. The fuse element2composed of a laminated body having a three-layer structure is obtained by the above process.

(Shielding Member)

The shielding member3, as illustrated inFIG.1toFIG.6, is composed of a first shielding member3aand a second shielding member3bhaving the same shape as the first shielding member3a. In the present embodiment, the first shielding member3aand the second shielding member3bhave the same shape; therefore, using the same material for manufacturing is preferable to be able to reduce the types of components to be manufactured. The first shielding member3aand the second shielding member3bmay be formed of different materials.

In the present embodiment, a case where both the first shielding member3aand the second shielding member3bare provided is described as an example of the shielding member3; however, the shielding member3may have only one from among the first shielding member3aand the second shielding member3b.

In the present embodiment, since both the first shielding member3aand the second shielding member3bare provided as the shielding member3, pressure elevation inside the housing portion60when the fuse element2fuses causes the first shielding member3aand the second shielding member3bto rotate. Also, the first shielding member3adivides the inside of the housing portion60, the second shielding member3balso divides the inside of the housing portion60. Therefore, when the shielding member3has both the first shielding member3aand the second shielding member3b, an arc discharge generated when the fuse element2fuses is suppressed (extinguished) more quickly and reliably in comparison to when there is only one from among the first shielding member3aand the second shielding member3b.

In the present embodiment, as illustrated inFIG.3andFIG.4, the second shielding member3bis disposed at a position of point symmetry with respect to the first shielding member3aand having, as an axis, the center of the fuse element2in the X-direction in an A-A′ cross-section. That is, the first shielding member3aand the second shielding member3bare disposed symmetrically in the X-direction with respect to the center of the fuse element2in the X-direction. Accordingly, in the protection element100of the present embodiment, even though pressure elevation in the housing portion60when the fuse element2fuses causes the first shielding member3aand the second shielding member3bto rotate simultaneously, there is no mutual interference and no hindrance is caused to their mutual rotational movements. Accordingly, the first shielding member3aand the second shielding member3bmore reliably divide the inside of the housing portion60at two locations in the housing portion60in the X-direction. Furthermore, since the first shielding member3aand the second shielding member3bbefore undergoing rotational movement may be stably disposed at a predetermined position in the housing portion60together with the fuse element2, the protection element100has excellent reliability.

Moreover, in the present embodiment, the fuse element2has the cut portion23between the first end portion21and the second end portion22, and as illustrated inFIG.5andFIG.6, the first shielding member3aand the second shielding member3brotate, and the first shielding member3aand the second shielding member3bthereby divide the inside of the housing portion60at two locations in proximity to the inside of the housing portion60in the X-direction interposing the cut portion23. As a result, an arc discharge generated when the fuse element2fuses is more quickly and reliably suppressed (extinguished).

In the present embodiment,FIG.8AtoFIG.8BandFIG.9will be used to describe a structure of the first shielding member3a. A structure of the second shielding member3bis the same as that of the first shielding member3a; therefore, the description will be omitted.

FIG.8AtoFIG.8Bare drawings for describing the structure of the first shielding member3aprovided in the protection element100of the first embodiment.FIG.8Ais a perspective view looking from the housing portion side, andFIG.8Bis a perspective view looking from the fuse element side.FIG.9is a drawing for describing the structure of the first shielding member3aprovided in the protection element100of the first embodiment.FIG.9(a)is a plan view looking from the fuse element side,FIG.9(b)is a plan view looking from the housing portion side, andFIGS.9(c) to (e)are side views.

The first shielding member3ais interposed between the fuse element2and a first case6acontaining the housing portion60. “Fuse element side” refers to a side of the first shielding member3awhereon the fuse element2is disposed. “Housing portion side” refers to a side of the first shielding member3awhereon the first case6acontaining the housing portion60is disposed.

As illustrated inFIG.1toFIG.9, the first shielding member3ahas a plate-shaped part30. The plate-shaped part30has a substantially rectangular shape in a plan view, and has, as illustrated inFIG.4, a first surface31disposed facing the fuse element2, and a second surface32disposed facing a bottom surface (a first bottom surface68cor a second bottom surface68d) of a concave portion68formed in the housing portion60of the case6.

The first surface31of the plate-shaped part30is disposed in proximity to or in contact with the fuse element2, and as illustrated inFIG.3andFIG.4, it is preferable that it be disposed in contact with the fuse element2, and it is more preferable that the entire surface of the first surface31be disposed in contact with the fuse element2. When the first surface31is disposed in contact with the fuse element2, an arc discharge generated when the fuse element2fuses is further reduced.

The second surface32of the plate-shaped part30, as illustrated inFIG.3andFIG.4, is disposed in contact with the rotation axis33extending in the Y-direction. In the present embodiment, as illustrated inFIG.3andFIG.4, the rotation axis33is composed of a step inside the concave portion68formed in the housing portion60of the case6.

In the present embodiment, as illustrated inFIG.4, from among both ends in the X-direction in the first surface31of the plate-shaped part30of the first shielding member3aillustrated inFIG.8BandFIG.9, a first end edge31aclose to the rotation axis33is disposed on an inner side of the housing portion60in the X-direction, and a second end edge31bfar from the rotation axis33is disposed on an outer side of the housing portion60in the X-direction. As illustrated inFIG.6, the first shielding member3arotates, causing the first end edge31ato be pressed onto a bottom surface of a shielding member housing groove34provided on an inner surface of the housing portion60. Furthermore, the first shielding member3arotates, causing the second end edge31bto be housed in the concave portion68.

In the present embodiment, as illustrated inFIG.4, from among both ends in the X-direction in the second surface32of the plate-shaped part30of the first shielding member3aillustrated inFIG.8AandFIG.9, a first end edge32aclose to the rotation axis33is disposed on an inner side of the housing portion60in the X-direction, and a second end surface32bdisposed on the second end portion far from the rotation axis33is disposed on an outer side of the housing portion60in the X-direction.

In the first shielding member3a, as illustrated inFIG.9(a), an area of the plate-shaped part30viewed from the fuse element2is different between a first area30aand a second area30bdivided at a contact position33abetween the plate-shaped part30and the rotation axis33. Note that the contact position33abetween the plate-shaped part30and the rotation axis33is not only a position where the second surface32of the plate-shaped part30contacts the rotation axis33—a position of the first surface31facing the contact position33aof the second surface32is also the contact position33a. In the present embodiment, as illustrated inFIG.9(a), the first area30adisposed on the first end edge31aside close to the rotation axis33is a narrower area than the second area30bdisposed on the second end edge31bside far from the rotation axis33.

Pressure elevation in the housing portion60due to an arc discharge generated when the fuse element2fuses causes, as illustrated inFIG.5andFIG.6, the first surface31to be pressed and the first shielding member3arotates around the rotation axis33. In the present embodiment, as for pressing force on the first surface31due to pressure elevation in the housing portion60, from among the first area30aand the second area30billustrated inFIG.9(a)the force on the second area30bhaving a wide area is relatively stronger than the force on the first area30ahaving a narrow area. Accordingly, pressing force on the second end edge31bside of the first surface31is stronger than the pressing force on the first end edge31aside. Therefore, the first shielding member3a, as illustrated inFIG.6, rotates in a direction in which the second end edge31bside disposed on an outer side of the housing portion60in the X-direction is separated from the fuse element2(a direction moving away from the fuse element2), and a direction in which the first end edge31aside disposed on an inner side of the housing portion60in the X-direction moves closer to the fuse element2.

As illustrated inFIG.8AandFIG.9(b), a convex portion38is vertically disposed at a center portion of the second end surface32bof the second surface32in the Y-direction. The convex portion38has a quadrangular prism shape. One surface of the side surfaces of the convex portion38is a flat surface that is continuous with a side surface of the plate-shaped part30in the X-direction.

As illustrated inFIG.5andFIG.6, when the fuse element2fuses, the convex portion38is housed in a guide hole66and functions as a guide for causing the first shielding member3ato undergo rotational movement to a predetermined position. Accordingly, since the first shielding member3ahas the convex portion38, the first shielding member3aeasily undergoes rotational movement to a predetermined position when the fuse element2fuses. As a result, rotation of the first shielding member3acauses the inside of the housing portion60to be divided more reliably.

In the present embodiment, the convex portion38is disposed at a center portion of the second end surface32bof the second surface32in the Y-direction; therefore, misalignment of the first shielding member3athat undergoes rotational movement when the fuse element2fuses is more effectively prevented.

In the present embodiment, as illustrated inFIG.8A,FIG.9(b), andFIG.9(e), the second end surface32bof the second surface32is an inclined surface, chamfered at a width corresponding to a dimension of the convex portion38in the X-direction. Therefore, as illustrated inFIG.6, the second end surface32bof the second surface32is not brought into contact with the second bottom surface68dof the concave portion68, which will be described later, preventing entry of the convex portion38accompanying the rotational movement of the first shielding member3a-into the guide hole66from being hindered. Accordingly, the first shielding member3aeasily undergoes rotational movement to a predetermined position when the fuse element2fuses. Furthermore, since it is not necessary to deepen the concave portion68to avoid contact between the second bottom surface68dand the convex portion38accompanying the rotational movement of the first shielding member3a, the protection element100may be miniaturized. Moreover, since it is not necessary to deepen the concave portion68, a thickness of the case6may be secured, and a strength of the case6may be secured.

A size of the concave portion38, as illustrated inFIG.3andFIG.4, is of a dimension that may be housed in the convex portion68formed in the housing portion60in a state prior to the first shielding member3arotating, and, as illustrated inFIG.5andFIG.6, that may be housed in the guide hole66formed in the concave portion68when the first shielding member3ahas rotated. In the present embodiment, a dimension of the convex portion38in the X-direction and a length from the second surface32to an apex portion of the convex portion38are substantially the same as a thickness of the plate-shaped part30, and a dimension of the convex portion38in the Y-direction is longer than the dimension in the X-direction.

In the present embodiment, a case where the convex portion38is provided having the foregoing quadrangular prism shape is given as an example; however, the shape of the convex portion is not limited to the foregoing quadrangular prism shape, and, for example, it may be a square prism shape, and the dimension in the Y-direction may be shorter than the dimension in the X-direction. Furthermore, the shape of the convex portion may be, for example, a columnar shape having a cross-sectional shape such as a circular shape, an oval shape, an elliptical shape, a triangular shape, a hexagonal shape, or the like.

Furthermore, in the present embodiment, a case where the convex portion38is disposed at a center portion of the second surface32in the Y-direction is described as an example; however, the position of the convex portion in the Y-direction need not be at a center portion on the second surface32.

Furthermore, in the present embodiment, a case where the shielding member has a convex portion is described as an example; however, the convex portion is provided as necessary so that the shielding member easily undergoes rotational movement to a predetermined position, and need not be provided. Even in the case where the shielding member does not have the convex portion, it is preferable to provide the guide hole66in the concave portion68so that gas inside the housing portion60generated by an arc discharge when the fuse element2fuses is discharged to an internal pressure buffer space71.

The first shielding member3aand the second shielding member3bare composed of an insulating material. A ceramic material, a resin material, or the like may be used as the insulating material.

Alumina, mullite, zirconia, or the like may be exemplified as a ceramic material, and it is preferable to use a material having high thermal conductivity, such as alumina. When the first shielding member3aand the second shielding member3bare formed of a material having high thermal conductivity, such as a ceramic material, the heat generated when the fuse element2fuses may be efficiently dissipated to the outside. Accordingly, continuation of an arc discharge generated when the fuse element2fuses is more effectively suppressed.

It is preferable to use any one selected from polyphenylene sulfide (PPS) resin, nylon-based resin, fluorine resin such as polytetrafluoroethylene or the like, or polyphthalamide (PPA) resin as a resin material, and using a nylon-based resin is particularly preferable.

An aliphatic polyamide may be used or a semi-aromatic polyamide may be used as the nylon-based resin. When using an aliphatic polyamide that does not contain a benzene ring as a nylon-based resin, even if the first shielding member3aand/or the second shielding member3bare burned by the arc discharge generated when the fuse element2fuses, graphite is less likely to be generated compared to when using a semi-aromatic polyamide that does have a benzene ring. Therefore, using aliphatic polyamide to form the first shielding member3aand the second shielding member3bmay prevent formation of a new conduction path due to graphite generated when the fuse element2fuses.

For example, Nylon 4, Nylon 6, Nylon 46, Nylon 66, or the like may be used as the aliphatic polyamide.

For example, Nylon 6T, Nylon 9T, or the like may be used as the semi-aromatic polyamide.

Among these nylon-based resins, it is preferable to use a resin that does not contain a benzene ring, such as Nylon 4, Nylon 6, Nylon 46, Nylon 66, or the like, which are aliphatic polyamides, and it is more preferable to use Nylon 46 or Nylon 66 due to their excellent heat resistance.

For example, when the shielding member3in the protection element100and the case6and the cover4are composed of Nylon 66, which is an aliphatic polyamide, an insulation resistance after current interruption is 10 to 10,000 times higher in comparison to when they are composed of Nylon 9T, which is a semi-aromatic polyamide having a benzene ring.

It is preferable to use a material having a tracking resistance index CTI equal to or more than 400 V as the resin material, and more preferably equal to or more than 600 V. Tracking resistance may be obtained by a test based on IEC 60112.

A nylon-based resin is particularly preferable among the resin materials due to high tracking resistance (resistance against tracking (carbonized conductive path) destruction).

It is preferable to use a material having a high glass transition temperature as the resin material. The glass transition temperature (Tg) of the resin material is the temperature at which the material changes from a soft rubbery state to a hard glassy state. When the resin is heated to equal to or more than the glass transition temperature, the molecules become more mobile and the resin changes to a soft rubbery state. On the other hand, when the resin is cooled, movement of the molecules is restricted and the resin changes to a hard glassy state.

The first shielding member3aand the second shielding member3bmay be manufactured by a known method.

(Case)

The case6, as illustrated inFIG.1toFIG.3, has a substantially cylindrical shape. The case6is composed of the first case6aand a second case6b, and the first case6aand the second case6bare disposed facing the fuse element2. One portion of the first terminal61and on portion of the second terminal62are sandwiched between the first case6aand the second case6band fixed by the cover4.

As illustrated inFIG.1toFIG.3, the first case6aand the second case6bare the same shape, which is a semi-cylindrical shape. In the present embodiment, the first case6aand the second case6bhave the same shape; therefore, using the same material for manufacturing is preferable to be able to reduce the types of components to be manufactured. The first case6aand the second case6bmay also be formed of different materials.

In the present embodiment, the first case6aand the second case6bhave the same shape, and are disposed facing each other via the fuse element2; therefore, stress caused by pressure elevation in the housing portion60when the fuse element2fuses is evenly distributed and applied to the first case6aand the second case6b. Thus, the case6has excellent strength and may effectively prevent breakage of protection element100when the fuse element2fuses.

As illustrated inFIG.1toFIG.3, the housing portion60is provided on the inside of the case6. The housing portion60is formed by integrating the first case6aand the second case6b. The fuse element2, the first shielding member3a, and the second shielding member3bare stored in the housing portion60.

As illustrated inFIG.3, two insertion holes64that open in the housing portion60are disposed facing each other in the X-direction in the housing portion60. The two insertion holes64are respectively formed by integrating the second case6band the first case6a.

As illustrated inFIG.3, one of the two insertion holes64houses the first end portion21of the fuse element2, and the other insertion hole64houses the second end portion22of the fuse element2.

As illustrated inFIG.1andFIG.3, one portion of the first terminal61and one portion of the second terminal62connected to the fuse element2are exposed to the outside of the case6.

In the present embodiment,FIG.10AtoFIG.10CandFIG.11will be used to describe a structure of the first case6a. A structure of the second case6bis the same as that of the first case6a; therefore, the description will be omitted.

FIG.10AtoFIG.10Care drawings for describing the structure of the first case6aprovided in the protection element100of the first embodiment.FIG.10Ais a perspective view of the first case6alooking from the outside, andFIG.10BandFIG.10Care perspective views of the inside of the housing portion of the first case6a.FIG.11is a drawing for describing the structure of the first case6aprovided in the protection element100of the first embodiment.FIG.11(a)is a plan view of the inside of the housing portion of the first case6a,FIG.11(b)is a plan view of the first case6alooking from the outside, andFIGS.11(c) to (e)are side surface views of the first case6a.

As illustrated inFIG.10B,FIG.10C, andFIG.11(a), an XY surface of the first case6afacing the second case6bhas a substantially rectangular shape having a long side in the X-direction and a short side in the Y-direction in a plan view, and has a shape wherein the length in the Y-direction of the X-direction center portion is short. As illustrated inFIG.10B,FIG.10C, andFIG.11(a), in the first case6a, by being integrated with the second case6b, the concave portion68, the shielding member housing groove34, and a fuse element-mounting surface65are provided in a region constituting an inner surface of the housing portion60.

As illustrated inFIG.10B,FIG.10C, andFIG.11(a), the concave portion68is a substantially rectangular shape in a plan view. As illustrated inFIG.4, the first shielding member3a(the second shielding member3bin the case of the second case6b) is housed in the concave portion68. In the present embodiment, as illustrated inFIG.4,FIG.10C, andFIG.11(a), a first wall surface68adisposed on an inner side of the first case6ain the X-direction, from among the inner wall surfaces of the concave portion68, is disposed substantially at the center of the first case6ain the X-direction. Accordingly, the first wall surface68ais disposed overlapping the cut portion23of the fuse element2in the Z-direction (seeFIG.4).

As illustrated inFIG.4, a bottom surface of the concave portion68is a surface facing the second surface32in the plate-shaped part30of the first shielding member3a(the second shielding member3bin the case of the second case6b). The bottom surface of the concave portion68, as illustrated inFIG.10B,FIG.10C, andFIG.11(a), has the first bottom surface68cdisposed on the first wall surface68aside, and the second bottom surface68ddisposed on a second wall surface68bside facing the first wall surface68a. The first bottom surface68cis provided at a position closer to the surface facing the fuse element2in the Z-direction than the second bottom surface68d. As a result, as illustrated inFIG.4andFIG.10C, a step extending in the Y-direction is formed at a boundary portion between the first bottom surface68cand the second bottom surface68d. In the present embodiment, as illustrated inFIG.4andFIG.10C, a step formed in the concave portion68of the first case6afunctions as the rotation axis33of the first shielding member3a(the rotation axis33of the second shielding member3bin the case of the second case6b).

As illustrated inFIG.4andFIG.10C, a position in the X-direction of the step (rotation axis33) formed in the concave portion68of the first case6ais at a position closer to the first wall surface68athan the second wall surface68b. As a result, as illustrated inFIG.9(a), among the areas of the plate-shaped part30of the first shielding member3a(the second shielding member3bin the case of the second case6b) looking from the fuse element2, the first area30adisposed on the first end edge31aside closer to the rotation axis33than the contact position33abetween the plate-shaped part30and the rotation axis33is narrower than the second area30bdisposed on the second end edge31bside farther from the rotation axis33.

In the present embodiment, a ratio of a length of the first bottom surface68cin the X-direction to a length of the concave portion68in the X-direction (length of the first bottom surface68c/concave portion68in the X-direction) is substantially the same as a ratio between the area of the plate-shaped part30and the first area30a(area of the first area30a/plate-shaped part30), which is less than 0.5, preferably 0.2 to 0.49, and more preferably 0.3 to 0.4.

Here, the length of the concave portion68in the X-direction is the length from the first wall surface68aof the concave portion68to the second wall surface68bin the X-direction.

When the ratio of the length of the first bottom surface68cin the X-direction to the length of the concave portion68in the X-direction is equal to or less than 0.4, the difference between the first area30aand the second area30bincreases sufficiently. As a result, regarding the pressing force on the first surface31of the plate-shaped part30of the first shielding member3adue to pressure elevation in the housing portion60, the difference between the second end edge31bside and the first end edge31aside also increases. Therefore, pressing force due to pressure elevation in the housing portion60is efficiently converted into driving force for causing the first shielding member3ato undergo rotational movement. As a result, the first shielding member3a, as illustrated inFIG.6, rotates at a sufficient rotational speed in a direction in which the second end edge31bside disposed on an outer side of the housing portion60in the X-direction is separated from the fuse element2, and a direction in which the first end edge31aside disposed on an inner side of the housing portion60in the X-direction moves closer to the fuse element2. Also, the first end edge31ais pressed by a strong force onto the bottom surface of the shielding member housing groove34provided on an inner surface of the housing portion60. From this, when the ratio of the length of the first bottom surface68cin the X-direction to the length of the concave portion68in the X-direction is equal to or less than 0.4, the first end edge31aof the first surface31of the plate-shaped part30, a portion in contact with the rotation axis33of the second surface32, and a side surface of the plate-shaped part30more reliably block and divide the inside of the housing portion60.

When the ratio of the length of the first bottom surface68cin the X-direction to the length of the concave portion68in the X-direction is equal to or more than 0.3, the area of the first bottom surface68cmay be sufficiently secured. Therefore, the first bottom surface68cmay more stably hold the first shielding member3aprior to undergoing rotational movement at a predetermined position in the first case6a. As a result, the protection element100is more excellent in reliability.

In the present embodiment, a case where the first bottom surface68cis disposed on the first wall surface68aside of the concave portion68, and the second bottom surface68dis disposed on the second wall surface68bside is described as an example; however, the second bottom surface68dmay be disposed on the first wall surface68aside of the concave portion68, and the first bottom surface68cmay be disposed on the second wall surface68bside. In this case, a position in the X-direction of the step (rotation axis33) formed in the concave portion68of the first case6ais at a position closer to the second wall surface68bthan the first wall surface68a. Accordingly, from among both ends in the X-direction of the first surface31of the plate-shaped part30of the first shielding member3a, the first end edge31aclose to the rotation axis33is disposed on an outer side of the housing portion60in the X-direction, and the second end edge31bfar from the rotation axis33is disposed on an inner side of the housing portion60in the X-direction. Also, a rotation direction of the first shielding member3ais an opposite direction to the protection element100of the present embodiment.

In the present embodiment, the first bottom surface68cis disposed on the first wall surface68aside of the concave portion68, and the second bottom surface68dis disposed on the second wall surface68bside; therefore, in the housing portion60, a position in the X-direction blocked by the first shielding member3aand a position in the X-direction blocked by the second shielding member3bare in proximity and are also closer to the cut portion23(heatspot) in comparison to when the second bottom surface68dis disposed on the first wall surface68aside and the first bottom surface68cis disposed on the second wall surface68bside. Therefore, an arc discharge generated when the fuse element2fuses is further reduced, and this is preferable.

In the present embodiment, it is preferable that the length of the concave portion68in the Y-direction is such that the plate-shaped part30of the first shielding member3afits inside the concave portion68while being in contact with an inner wall surface of the concave portion68. In this case, pressure elevation inside the housing portion60when the fuse element2fuses allows the first shielding member3ato rotate. Moreover, the first shielding member3arotates, causing the first end edge31aof the first surface31of the plate-shaped part30, a portion in contact with the rotation axis33of the second surface32, and a side surface of the plate-shaped part30to block and divide the inside of the housing portion60more reliably. Moreover, the first shielding member3aprior to undergoing rotational movement may be held more stably at a predetermined position in the first case6a. Specifically, a distance separating the inner wall surface facing the concave portion68in the Y-direction and the plate-shaped part30is, for example, preferably 0.05 to 0.2 mm, and more preferably 0.05 to 0.1 mm.

As illustrated inFIG.11(a), one guide hole66and two bottom surface vents69are provided in the second bottom surface68dof the concave portion68. As illustrated inFIG.11(a)andFIG.11(b), the one guide hole66and the two bottom surface vents69pass through the first case6ain the Z-direction and open to the second bottom surface68dand an outer surface of the first case6a.

The guide hole66discharges gas inside the housing portion60—generated by an arc discharge when the fuse element2fuses—to the internal pressure buffer space71. When the fuse element2fuses, the guide hole66also functions together with the convex portion38of the first shielding member3aas a guide for causing the first shielding member3ato undergo rotational movement to a predetermined position. The guide hole66has a dimension wherein the convex portion38of the first shielding member3amay be housed when the first shielding member3ahas rotated.

The guide hole66has a substantially rectangular shape in a plan view. An inner wall surface on the outer side of the guide hole66in the X-direction, as illustrated inFIG.4,FIG.10B, andFIG.11(b), is disposed at a position further to the outer side in the X-direction than the second wall surface68band, as illustrated inFIG.4andFIG.10B, is formed extending to a position closer to the surface facing the fuse element2than the second bottom surface68d. Therefore, even if the first shielding member3aundergoes rotational movement when the fuse element2fuses and the convex portion38is housed in the guide hole66, the guide hole66is not obstructed by the shielding member3. Accordingly, gas in the housing portion60generated by an arc discharge may be reliably discharged to the internal pressure buffer space71. Furthermore, as illustrated inFIG.6, the first shielding member3arotates, causing the second end edge31bof the first surface31of the plate-shaped part30to be easily housed in the concave portion68along the inner wall surface of the guide hole66. Moreover, since the first case6ahas the second wall surface68b, the first case6amay hold the first shielding member3abefore the rotational movement at a predetermined position along the second wall surface68bwith high accuracy and more stability.

The bottom surface vent69has a substantially cylindrical shape. The bottom surface vent69controls pressure elevation in the concave portion68when the fuse element2fuses and thereby controls arc discharge.

In the present embodiment, a case where the bottom surface vent69having a substantially cylindrical shape is provided is described as an example; however, the shape of the vent is not limited to a substantially cylindrical shape—for example, it may be a long cylindrical shape, an elliptical cylindrical shape, a polygonal cylindrical shape, or the like.

Two bottom surface vents69are disposed symmetrically with respect to the center in the Y-direction, as illustrated inFIG.11(a). Therefore, when the fuse element2fuses, gas inside the housing portion60is easily discharged to the outside of the housing portion60evenly and quickly via the two bottom surface vents69, which is preferable.

In the present embodiment, a case where two bottom surface vents69are provided is described as an example; however, the number of bottom surface vents is not particularly limited—it may be one or may be three or more, and the bottom surface vent69need not be provided. When the bottom surface vent69is not provided, it is preferable to have the guide hole66and/or a side surface vent77, which will be described later.

As illustrated inFIG.3,FIG.10B,FIG.10C, andFIG.11(a), on a surface on the housing portion60side of the first case6a, the shielding member housing groove34is provided on an opposite side to the concave portion68in a plan view with respect to the substantial center in the X-direction. The shielding member housing groove34has a substantially rectangular shape, and is composed of a groove having a flat bottom surface in a plan view. As illustrated inFIG.5andFIG.6, the first shielding member3arotates, causing one portion of the plate-shaped part30to be housed in the shielding member housing groove34. In the present embodiment, a length of the shielding member housing groove34in the Y-direction is longer than the length of the first shielding member3ain the Y-direction. Therefore, the first shielding member3arotates, causing the entire first end edge31aon the first surface31of the plate-shaped part30to be disposed in contact with the top of the bottom surface of the shielding member housing groove34.

In the present embodiment, as illustrated inFIG.10B,FIG.10C, andFIG.11(a), an outer side of an edge portion facing the shielding member housing groove34in the Y-direction is a joining surface70that is joined to the second case6b. Therefore, the first shielding member3arotates in a state where the first case6aand the second case6bare joined, causing the first end edge31aof the first surface31and a portion in contact with the rotation axis33of the second surface32of the plate-shaped part30, and a side surface of the plate-shaped part30to block and divide the inside of the housing portion60more reliably.

A depth of the shielding member housing groove34is preferably 0.5 to 2 times and more preferably 0.5 to 1 times the thickness of the fuse element2. When the depth of the shielding member housing groove34is equal to or more than 0.5 times the thickness of the fuse element2, the inside of the housing portion60may be more reliably divided by the first shielding member3arotating. Furthermore, when the depth of the shielding member housing groove34is equal to or less than two times the thickness of the fuse element2, a function of the shielding member housing groove34as a stopper causes a range in which the first shielding member3aundergoes rotational movement to be appropriate. Therefore, to avoid contact between the first shielding member3aand the concave portion68accompanying the rotational movement of the first shielding member3a, it is not necessary that a size of the concave portion68is excessively increased, and that miniaturization of the protection element100is not hindered.

Furthermore, it is preferable that a distance in the Z-direction between a surface of the fuse element2and an inner wall of the housing portion60is short to effectively control continuation of an arc discharge generated when the fuse element2fuses. As illustrated inFIG.4, a distance in the Z-direction between a surface of the fuse element2and the bottom surface of the fuse element-mounting surface65is shorter than the distance in the Z-direction between a surface of the fuse element2and the bottom surface of the shielding member housing groove34. Accordingly, it is preferable to shorten the length of the shielding member housing groove34in the X-direction to increase a region—from among the surfaces of the fuse element2—facing the fuse element-mounting surface65.

When the depth of the shielding member housing groove34is equal to or less than two times the thickness of the fuse element2, even if the length of the shielding member housing groove34in the X-direction is short, the first end edge31aon the first surface31of the plate-shaped part30may be disposed in contact with the top of the bottom surface of the shielding member housing groove34without excessive rotational movement of the first shielding member3a. Accordingly, from among the surfaces of the fuse element2, the ratio of the region facing the fuse element-mounting surface65may be increased, and an arc discharge generated when the fuse element2is cut may be controlled.

As illustrated inFIG.10B,FIG.10C, andFIG.11(a), on a surface on the housing portion60side of the first case6a, the fuse element-mounting surface65composed of a concave portion is provided on an outer side of the shielding member housing groove34in the X-direction in a plan view. A step is formed at a boundary portion between the fuse element-mounting surface65and the shielding member housing groove34, and at a boundary portion between the fuse element-mounting surface65and the joining surface70joined to the second case6b. In the present embodiment, a depth of the concave portion forming the fuse element-mounting surface65is preferably equal to or less than the thickness dimension of the fuse element2, and, for example, may be a dimension half the thickness of the fuse element2.

The bottom surface of the fuse element-mounting surface65is disposed in proximity to or in contact with the fuse element2, and as illustrated inFIG.4, it is preferable that it be disposed in contact with the fuse element2. When the bottom surface of the fuse element-mounting surface65is disposed in contact with the fuse element2, an arc discharge generated when the fuse element2fuses is further reduced.

In the present embodiment, the distance between the bottom surface of the fuse element-mounting surface65of the first case6a(second case6b) and the second shielding member3b(first shielding member3a) disposed facing via the fuse element2in the Z-direction is preferably equal to or less than ten times the thickness of the fuse element2, more preferably equal to or less than five times, and even more preferably equal to or less than two times; it is particularly preferable that the fuse element2is in contact with the bottom surface of the fuse element-mounting surface65of the first case6a(second case6b) and/or the second shielding member3b(first shielding member3a). When the foregoing distance in the Z-direction is equal to or less than ten times the thickness of the fuse element2, the number of lines of electric force generated by an arc discharge is reduced, and an arc discharge generated when the fuse element2is fused is reduced. Furthermore, since the foregoing distance in the Z-direction is short, the protection element100may be miniaturized.

As illustrated inFIG.10B,FIG.10C, andFIG.11(a), a leak prevention groove35extending in the Y-direction is provided at a position on an outer side in the X-direction on the bottom surface of the fuse element-mounting surface65. When the fuse element2fuses, and the melted fuse element2disperses and dispersed matter attaches to the inside of the housing portion60, the leak prevention groove35divides a conduction path formed by the adhered matter to prevent a leak current.

It is preferable that a length of the leak prevention groove35in the Y-direction is longer than the width21D in the Y-direction in the first end portion21and the width22D in the Y-direction in the second end portion22of the fuse element2. In this case, it is possible to prevent dispersed matter adhered to the inside of the housing portion60when the fuse element2fuses from being electrically connected to the first terminal61or the second terminal62more effectively, and it is possible to prevent generation of a leak current more effectively.

The leak prevention groove35is formed at a substantially fixed width and depth. The width and depth of the leak prevention groove35are not particularly limited, provided that the leak prevention groove35is able to divide a conduction path formed by adhered matter dispersed when the fuse element2fuses and prevent a leak current.

In the protection element100of the present embodiment, it is preferable that the leak prevention groove35is provided; however, the leak prevention groove35need not be provided. Furthermore, it is preferable that the leak prevention groove35be provided extending in the Y-direction to a position on an outer side in the X-direction on the bottom surface of the fuse element-mounting surface65; however, it may be at another position on the bottom surface of the fuse element-mounting surface65, or it need not extend in the Y-direction.

As illustrated inFIG.10AtoFIG.10CandFIG.11(a), a side surface concave portion77acomposed of a concave portion is respectively provided at an edge portion of the concave portion68facing in the Y-direction, where the position in the X-direction is within a range where the second bottom surface68dis formed. As illustrated inFIG.10BandFIG.10C, a step is formed at a boundary portion between the side surface concave portion77adisposed at an edge portion of the concave portion68and the joining surface70joined to the second case6b.

As illustrated inFIG.10AtoFIG.10CandFIG.11(a), the side surface concave portion77acomposed of a flat surface continuous from the bottom surface of the fuse element-mounting surface65is respectively provided at an edge portion of the fuse element-mounting surface65facing in the Y-direction, at which the position in the X-direction is further to the center side than the leak prevention groove35. As illustrated inFIG.10BandFIG.10C, a step is formed at a boundary portion between the side surface concave portion77adisposed at an edge portion of the fuse element-mounting surface65and the joining surface70joined to the second case6b.

Four side surface concave portions77aprovided at the edge portions of the concave portion68of the first case6aare each integrated with the second case6bto form four side surface vents77passing through the case6together with four side surface concave portions77aprovided in the second case6b(seeFIG.1). The side surface vent77controls pressure elevation in the housing portion60when the fuse element2fuses and thereby controls arc discharge.

In the present embodiment, two side surface concave portions77adisposed on the edge portions of the concave portion68and two side surface concave portions77adisposed on the edge portions of the fuse element-mounting surface65all have a depth of a dimension that is half the thickness of the fuse element2. Furthermore, the two side surface concave portions77adisposed on the edge portions of the concave portion68and two side surface concave portions77adisposed on the edge portions of the fuse element-mounting surface65have the same shape, and are disposed symmetrically with respect to the center of the housing portion60in the X-direction. Therefore, the four side surface vents77formed by integration of the first case6aand the second case6bare disposed at a position where gas in the housing portion60generated when the fuse element2fuses is easily discharged outside of the housing part60evenly and quickly, and this is preferable.

In the present embodiment, a case where the depth of the side surface concave portion77ais a dimension that is half the thickness of the fuse element2is described as an example; however, the depth of the side surface concave portion77ais not particularly limited. Furthermore, in the present embodiment, a case where four side surface concave portions77ahave the same shape is described as an example; however, of the four side surface concave portions77a, one part or all may have a different shape.

In the present embodiment, a case where four side surface vents77are provided is described as an example; however, the number of side surface vents is not particularly limited—it may be equal to or less than three or equal to or less than five, and a side surface vent need not be provided. When the side surface vent77is not provided, it is preferable to have the guide hole66and/or the bottom surface vent69.

As illustrated inFIG.10B,FIG.10C, andFIG.11(a), on a surface on the housing portion60side of the first case6a, an insertion hole-forming surface64acomposed of a concave portion is respectively provided on an outer side of the concave portion68and the fuse element-mounting surface65in the X-direction in a plan view. A step is formed at a boundary portion between each insertion hole-forming surface64aand the joining surface70joined to the second case6b. The step between the insertion hole-forming surface64aand the joining surface70has a dimension capable of forming the insertion hole64that is able to house a laminated portion of the first terminal61(or second terminal62) and the fuse element2by the first case6aand second case6bbeing integrated.

A length of the insertion hole-forming surface64ain the Y-direction is longer than the width21D in the Y-direction in the first end portion21and the width22D in the Y-direction in the second end portion22of the fuse element2. Therefore, the widths21D and22D direction entire surface of the first end portion21and the second end portion22of the fuse element2are disposed on the insertion hole-forming surface64a.

As illustrated inFIG.10B,FIG.10C, andFIG.11(a), a terminal-mounting surface64bcomposed of a concave portion is respectively provided so as to surround in a plan view an outer side of two insertion hole-forming surfaces64ain the X-direction and one portion of an outer side of the insertion hole-forming surfaces64ain the Y-direction. The terminal-mounting surface64bhas an external shape corresponding to a planar shape of the first terminal61and the second terminal62. As a result, the first case6amay be easily aligned with the first terminal61and the second terminal62. Furthermore, it is difficult for the first terminal61and the second terminal62to come out of the case6.

For example, in the present embodiment, it is preferable that the terminal-mounting surface64bhas an external shape corresponding to a substantial T-shape, which is the planar shape of the first terminal61having the flange portion61cand the second terminal62having the flange portion62c. According to the present structure, the protection element100is obtained having favorable reliability and durability, wherein the flange portion61cand the flange portion62care unlikely to come out.

As illustrated inFIG.10BandFIG.10C, the terminal-mounting surface64bis provided at a position closer to the joining surface70joined to the second case6bin the Z-direction than a surface of the insertion hole-forming surface64a. As a result, a step is formed at a boundary portion between the terminal-mounting surface64band the insertion hole-forming surface64a. Furthermore, a step is also formed at a boundary portion between the terminal-mounting surface64band the joining surface70joined to the second case6b. The step between the terminal-mounting surface64band the joining surface70has a dimension capable of housing the first terminal61(or second terminal62) by integration of the first case6aand the second case6b.

As illustrated inFIG.10B,FIG.10C, andFIG.11(a), a notch78acomposed of a concave portion having a substantially semicircular-shaped bottom surface is respectively formed at a center portion in the Y-direction on an edge portion of an outer side of the two terminal-mounting surfaces64bin the X-direction. A first adhesive inlet78(seeFIG.1andFIG.3) having a substantially cylindrical shape looking from the X-direction is formed from each notch78aby integration of the first case6aand the second case6b.

As illustrated inFIG.10A to10CandFIG.11(a)toFIG.11(d), a notch76ais respectively formed at a position on each of the four corners of the first case6ain a plan view on the joining surface70—of the first case6a—joined to the second case6b. A second adhesive inlet76(seeFIG.1) that is hollow and having a semicircular columnar shape in a cross section looking from the X-direction is formed from each notch76aby integration of the first case6aand the second case6b.

As illustrated inFIG.10BandFIG.10C, a fitting concave portion63that is substantially circular in a plan view is respectively formed between the terminal-mounting surface64band two notches76aformed on the concave portion68side from among the four notches76aformed on the joining surface70—of the first case6a—joined to the second case6b.

Furthermore, as illustrated inFIG.10B,FIG.10C, andFIG.11(a), a fitting convex portion67that is substantially circular in a plan view is respectively formed between the terminal-mounting surface64band two notches76aformed on the fuse element-mounting surface65side from among the four notches76aformed on the joining surface70—of the first case6a—joined to the second case6b. Each fitting concave portion63is fitted to each fitting convex portion67by integrating the first case6aand the second case6b.

As illustrated inFIG.10A,FIG.11(b), andFIG.11(e), a first buffer concave portion73formed on a surface of an opposite side to the joining surface70joined to the second case6bis provided on an outer surface of the first case6a. Furthermore, as illustrated inFIG.10AtoFIG.10CandFIG.11(a), a second concave portion74is respectively provided on both side surfaces of the first case6ain the Y-direction. The second concave portion74is formed as a second buffer concave portion75(seeFIG.1) by integrating the first case6aand the second case6b. Furthermore, as illustrated inFIG.10AtoFIG.10CandFIG.11(b)toFIG.11(e), an end member72having a semi-cylindrical external shape is respectively provided at both end portions of an outer surface of the first case6ain the X-direction. The end member72is formed in a cylindrical shape by integrating the first case6aand the second case6b.

The first buffer concave portion73and the second concave portion74(second buffer concave portion75) form the internal pressure buffer space71surrounded by an inner surface of the cover4and an outer surface of the case6formed by integration of the first case6aand the second case6b. The internal pressure buffer space71is provided in an annular shape along an inner surface of the cover4at a center portion of the cover4in the X-direction.

In the present embodiment, a length (thickness) of the end member72in the X-direction is sufficiently secured so as to be able to withstand stress caused by pressure elevation in the internal pressure buffer space71when the fuse element2fuses. Specifically, it is preferable that the length of the end member72in the X-direction is, for example, one to three times the thickness of the cover4.

As illustrated inFIG.11(a)andFIG.11(b), the guide hole66and the two bottom surface vents69passing through the first case6aand communicating between the housing portion60and the internal pressure buffer space71are opened in the first buffer concave portion73. Furthermore, as illustrated inFIG.1, two side surface vents77passing through the case6and communicating between the housing portion60and the internal pressure buffer space71, formed by integration of the side surface concave portion77aprovided in the first case6aand the side surface concave portion77aprovided in the second case6b, are open in two second buffer concave portions75formed by integrating the first case6aand the second case6b.

Gas in the housing portion60generated when the fuse element2fuses flows into the internal pressure buffer space71from inside the housing portion60via the side surface vent77, the guide hole66, and the bottom surface vent69. As a result, pressure elevation in the housing portion60when the fuse element2fuses is suppressed and arc discharge is suppressed. A volume of the internal pressure buffer space71is preferably equal to or more than a volume of the fuse element2, more preferably equal to or more than 100 times the volume of the fuse element2, and even more preferably equal to or more than 1,000 times the volume of the fuse element2since this may effectively suppress pressure elevation in the housing portion60.

It is preferable that an upper limit of the volume of the internal pressure buffer space71is 2,000 times the volume of the fuse element2.

The first case6aand the second case6bare composed of an insulating material. The same material that may be used for the first shielding member3aand the second shielding member3bmay be used as the insulating material. The first case6aand the second case6band the first shielding member3aand the second shielding member3bmay be composed of the same material or may be composed of different materials.

The first case6aand the second case6bmay be manufactured by a known method.

(Cover)

The cover4, as illustrated inFIG.1, fixes the first case6aand the second case6bwhile also covering a side surface along the case6in the X-direction. The cover4, as illustrated inFIG.1andFIG.3, exposes one portion of the first terminal61from a first end41and exposes one portion of the second terminal62from a second end42.

The cover4, as illustrated inFIG.2, has a cylindrical shape of a substantially uniform thickness, and as illustrated inFIG.3, has an inner diameter corresponding to a substantially cylindrical shape in which the end member72of the first case6aand the end member72of the second case6bare integrated. As illustrated inFIG.2andFIG.3, an edge portion on an inner side in an open portion of the cover4is a chamfered inclined surface4a.

In the present embodiment, an outer surface of the case6and an inner surface of the cover4seals a spatial region composed of the housing portion60and the internal pressure buffer space71.

In the present embodiment, the cover4has a cylindrical shape. Therefore, pressure on the cover4when the fuse element2fuses is distributed and applied substantially evenly over an entire inner surface of the cover4via the internal pressure buffer space71provided in an annular shape along an inner surface of the cover4at a center portion of the cover4in the X-direction, and the end member72housed along an inner surface of the cover4at an edge portion of the cover4in the X-direction. As a result, the cover4exhibits excellent strength and effectively prevents breakage of the protection element100when the fuse element2fuses. Furthermore, the cover4has a cylindrical shape and therefore, may be easily manufactured and has excellent productivity.

The cover4is composed of an insulating material. The same material that may be used for the first shielding member3aand the second shielding member3band the first case6aand the second case6bmay be used as the insulating material. The cover4, the first case6aand the second case6b, and the first shielding member3aand the second shielding member3bmay all be composed of different materials, or one part or all portions may be composed of the same material.

The cover4may be manufactured by a known method.

(Method of Manufacturing the Protection Element)

Next, a method of manufacturing the protection element100of the present embodiment will be described.

First, the fuse element2, the first terminal61, and the second terminal62are prepared to manufacture the protection element100of the present embodiment. Also, as illustrated inFIG.7, the first terminal61is connected on the first end portion21of the fuse element2by soldering. Furthermore, the second terminal62is connected on the second end portion22by soldering.

A known material may be used as a binder material used for soldering in the present embodiment, and it is preferable to use a material containing Sn as a main component from the perspective of resistivity and melting point, and being free from lead for the environment.

The first end portion21and the second end portion22of the fuse element and the first terminal61and the second terminal62may be connected by a joint made by welding, and a known joining method may be used.

Next, the first shielding member3aand the second shielding member3billustrated inFIG.8AtoFIG.8BandFIG.9and the first case6aand the second case6billustrated inFIG.10AtoFIG.10CandFIG.11are prepared.

Then, the first shielding member3ais installed inside the concave portion68of the first case6a. During this, as illustrated inFIG.4, the second surface32on the plate-shaped part30of the first shielding member3ais disposed in contact with the step (rotation axis33) formed inside the concave portion68of the first case6a. Furthermore, the second shielding member3bis installed inside the concave portion68of the second case6b. During this, as illustrated inFIG.4, the second surface32on the plate-shaped part30of the second shielding member3bis disposed in contact with the step (rotation axis33) formed inside the concave portion68of the second case6b.FIG.12Ais a perspective view of the second case6bwherein the second shielding member3bis installed, looking from a side constituting the housing portion60.

Next, as illustrated inFIG.12B, a member wherein the fuse element2is integrated with the first terminal61and the second terminal62is installed on the second case6bwherein the second shielding member3bis installed. In the present embodiment, mounting the first terminal61and the second terminal62to the two terminal-mounting surfaces64b, respectively, allows the fuse element2, the first terminal61, and the second terminal62to be aligned with respect to the second case6b.

In the present embodiment, as illustrated inFIG.12B, a case where a surface of the first terminal61and the second terminal62side at a connecting portion between the first terminal61and the second terminal62and the first end portion21and the second end portion22of the fuse element, respectively, is installed to face the second case6bis described; however, a surface of the fuse element2side may be installed to face the second case6b.

Next, the first case6a, wherein the first shielding member3ais installed, is installed on the second case6b, wherein the second shielding member3band the member in which the fuse element2, the first terminal61and the second terminal62are integrated. During this, the fitting concave portion63included in the first case6aand the fitting convex portion67included in the second case6bare fitted together, and the fitting convex portion67included in the first case6aand the fitting concave portion63included in the second case6bare fitted together. As a result, the first case6aand the second case6bare aligned.FIG.13Ais a perspective view illustrating a state wherein the first case6ais installed on the second case6bvia the fuse element2.

As illustrated inFIG.13A, the first case6ais installed on the second case6b, forming the second buffer concave portion75, the side surface vent77, the first adhesive inlet78, and the second adhesive inlet76. Furthermore, as illustrated inFIG.3, one of the insertion holes64houses the first end portion21of the fuse element2, the other insertion hole64houses the second end portion22of the fuse element2, and a state is formed where one portion of the first terminal61and one portion of the second terminal62connected to the fuse element2are exposed to the outside of the case6.

Next, as illustrated inFIG.13B, the first case6aand the second case6bare housed in the cover4while in an integrated state. As a result, the cover4covers the end member72forming a side surface along the case6in the X-direction, the first buffer concave portion73, and the second buffer concave portion75, and also fixes the first case6aand the second case6b.

Thereafter, an adhesive is injected into the inclined surface4aof the cover4, the first adhesive inlet78, and the second adhesive inlet76, respectively. An adhesive containing thermosetting resin, for example, may be used as the adhesive. As a result, the inside of the cover4is sealed, and as illustrated inFIG.1andFIG.3, an outer surface of the case6and an inner surface of the cover4seal a spatial region composed of the housing portion60and the internal pressure buffer space71.

The protection element100of the present embodiment is obtained by the foregoing process.

(Operation of the Protection Element)

Next, the operation of the protection element100will be described in a case where a current exceeding a rated current flows through the fuse element2of the protective element100of the present embodiment.

When a current exceeding a rated current flows through the fuse element2of the protection element100of the present embodiment, the temperature of the fuse element2rises due to heat generated by the overcurrent. Also, when the cut portion23of the fuse element2melts due to a temperature rise, it is fused or cut. During this time, a spark is generated between the cut surfaces or fused surfaces of the cut portion23, and an arc discharge is generated.

In the protection element100of the present embodiment, among the areas of the plate-shaped part30looking from the fuse element2of the first shielding member3aand the second shielding member3b, the first area30adisposed on the first end edge31aside close to the rotation axis33is narrower than the second area30bdisposed on the second end edge31bside far from the rotation axis33. Therefore, when pressure elevation in the housing portion60due to an arc discharge generated when the fuse element2fuses causes the first surface31on the plate-shaped part30included in the first shielding member3aand the second shielding member3bto be pressed, as illustrated inFIG.5andFIG.6, the first shielding member3arotates around the rotation axis33and the second shielding member3brotates around the rotation axis33.

In the present embodiment, the first shielding member3aand the second shielding member3b, as illustrated inFIG.6, rotate in a direction in which the second end edge31bside disposed on an outer side of the housing portion60in the X-direction is separated from the fuse element2, and a direction in which the first end edge31aside disposed on an inner side of the housing portion60in the X-direction moves closer to the fuse element2. Also, the first end edge31ais pressed onto the bottom surface of the shielding member housing groove34provided on an inner surface of the housing portion60. Furthermore, the second end edge31bis housed in the concave portion68.

As described above, the protection element100of the present embodiment is provided with the fuse element2energized in the X-direction; the first shielding member3aand the second shielding member3bcomposed of an insulating material, and having the plate-shaped part30wherein the first surface31is disposed facing the fuse element2and the second surface32is disposed in contact with the rotation axis33extending in the Y-direction, wherein the area of the plate-shaped part30viewed from the fuse element2is different between the first area30aand the second area30bdivided at the contact position33abetween the plate-shaped part30and the rotation axis33; and the case6composed of an insulating material, and provided internally with the housing portion60wherein the fuse element2and the first shielding member3aand the second shielding member3bare stored.

Also, in the protection element100of the present embodiment, pressure elevation in the housing portion60due to an arc discharge generated when the fuse element2fuses causes the first surface31of the first shielding member3aand the second shielding member3bto be pressed. Thus, as illustrated inFIG.5andFIG.6, the first shielding member3aand the second shielding member3beach rotate around the rotation axis33. As a result, the first shielding member3aand the second shielding member3bblock and divide the inside of the housing portion60at two locations in the X-direction.

During this, in the present embodiment, a space interposed between the first shielding member3aand the second shielding member3bis formed. This space is surrounded by a bottom surface of the shielding member housing groove34, the concave portion68, the first end edge31aof the first surface31of the plate-shaped part30provided with both the first shielding member3aand the second shielding member3b, a portion in contact with the rotation axis33of the second surface32, and a side surface of the plate-shaped part30.

Accordingly, in the present embodiment, the first shielding member3aand the second shielding member3bdivide the inside of the housing portion60, causing the fused surfaces or the cut surfaces of the cut or fused fuse element2to be insulated, the two insertion holes64open in the housing portion60to be separated from each other, and the current path to be interrupted. As a result, the arc discharge generated when the fuse element2fuses is quickly suppressed (extinguished).

That is, in the protection element100of the present embodiment, an arc discharge generated when the fuse element2fuses is reduced. Accordingly, in the protection element100of the present embodiment, the housing portion60may be prevented from breaking due to pressure elevation in the housing portion60, resulting in excellent safety.

The protection element100of the present embodiment may be preferably installed in a current path of, for example, a high voltage equal to or greater than 100 V and a large current equal to or greater than 100 A, and may also be installed on a current path of a high voltage equal to or greater than 400 V and a large current equal to or greater than 120 A.

Furthermore, the protection element100of the present embodiment has the case6composed of an insulating material, that exposes one portion of the first terminal61and one portion of the second terminal62electrically connected to the fuse element2energized in the X-direction, and for storing the fuse element2; and the cover4composed of an insulating material having a cylindrical shape, for covering a side surface along the case6in the X-direction, that exposes one portion of the first terminal61from the first end41, and that exposes one portion of the second terminal62from the second end42. Accordingly, in the protection element100of the present embodiment, stress caused by pressure elevation in the case6when the fuse element2fuses is applied to the case6and the cover4covering a side surface along the case6in the X-direction. Therefore, excellent strength against pressure elevation in the case6is obtained in comparison to when there is no cover4, for example. Thus, the protection element100of the present embodiment is unlikely to break when the fuse element2fuses and therefore has excellent safety.

In the protection element100of the present embodiment, it is more preferable that the fuse element2is composed of a laminated body wherein an inner layer composed of Sn or a metal containing Sn as a main component and an outer layer composed of Ag or Cu or a metal containing Ag or Cu as a main component are laminated in a thickness direction, and that the shielding member3, the case6, and the cover4are formed of a resin material. In this kind of protection element, an arc discharge generated when the fuse element2fuses is further reduced and further miniaturization is also possible due to the following reasons.

That is, when the fuse element2is composed of the foregoing laminated body, a fusing temperature of the fuse element2is as low as 300 to 400° C., for example. Accordingly, even if the shielding member3, the case6, and the cover4are composed of a resin material, sufficient heat resistance is obtained. Furthermore, since the fusing temperature of the fuse element2is low, even if the shielding member3and/or an inner surface of the housing portion60and the cut portion23of the fuse element2are disposed in contact with each other, the fuse element2reaches the fusing temperature in a short time. Accordingly, a distance in the Z-direction between the shielding member3and/or an inner surface of the housing portion60and the fuse element2may be made sufficiently short without hindering the function of the fuse element2.

Moreover, in this kind of protection element, the resin material forming the shielding member3, the case6, and the cover4is decomposed by the heat accompanying the fusing of the fuse element2to generate pyrolysis gas, and the vaporization heat thereof cools the inside of the housing portion60(ablation effect of resin). As a result, arc discharge is further reduced. Therefore, in a protection element wherein the fuse element2is composed of the foregoing laminated body and the shielding member3, the case6, and the cover4are formed of a resin material, the distance in the Z-direction between the shielding member3and/or an inner surface of the housing portion60and the fuse element2is shortened, and arc discharge may be further reduced while further miniaturization is possible.

Examples of resin materials that easily obtain an ablation effect due to the heat associated with fusing of the fuse element2include Nylon 46, Nylon 66, polyacetal (POM), polyethylene terephthalate (PET), and the like. It is preferable to use Nylon 46 or Nylon 66 as the resin material forming the shielding member3, the case6, and the cover4from the perspective of heat resistance and flame resistance.

The ablation effect of resin is more effectively obtained when the distance in the Y-direction of the concave portion68forming an inner surface of the housing portion60, the shielding member housing groove34, and the fuse element-mounting surface65and the distance in the Y-direction of the first surface31of the shielding member3is equal to or greater than 1.5 times the length of the fuse element2in the Y-direction (widths21D and22D). This is presumed to be because the surface area of the shielding member3and/or the surface area in the housing portion60is sufficiently wide, and decomposition of the resin material due to the heat accompanying the fuse element2fusing is accelerated, even when the shielding member3and/or an inner surface of the housing portion60and the cut portion23of the fuse element2are disposed in contact with each other.

On the other hand, for example, a protection element having a fuse element composed of Cu and a case composed of a ceramic material may be difficult to miniaturize due to the following reasons.

That is, when the fuse element is composed of Cu, the fusing temperature of the fuse element is a high temperature equal to or greater than 1,000° C. Therefore, when a resin material is used as the material of the case, there is a possibility that the heat resistance of the case will be insufficient. Accordingly, a ceramic material having excellent heat resistance is used as a material of the case.

In this protection element, the fusing temperature of the fuse element is high and a ceramic material is used as a material of the case; therefore, when the distance between the cut portion of the fuse element and an inner surface of the case is reduced, the heat generated at the cut portion is dissipated via the case, making it difficult for the fuse element to reach the fusing temperature. Therefore, it is necessary to secure a sufficient distance between the cut portion and an inner surface of the case. Thus, in a protection element wherein the fuse element is composed of Cu and the case is composed of a ceramic material, a wide housing portion must be provided in the case.

Moreover, when a sufficient distance is secured between the cut portion and an inner surface of the case, the number of lines of electric force generated by an arc discharge is increased; therefore, an arc discharge generated when the fuse element fuses is large. Therefore, it may be necessary to put an arc-extinguishing agent into the housing portion in the case to quickly suppress (extinguish) arc discharge. When the arc-extinguishing agent is put into the case, it is necessary to secure a space for housing the arc-extinguishing agent in the case. Therefore, it may be necessary to provide a wider housing portion in the case, which may make miniaturization even more difficult.

Second Embodiment

(Protection Element)

FIG.14is a cross-section view for describing a protection element200of a second embodiment, and is a cross-section view corresponding to a position at which the protective element100of the first embodiment is cut along line A-A′ illustrated inFIG.1.FIG.15is a drawing for describing the operation of the protection element200of the second embodiment, and is a cross-section view of a position corresponding to the cross-section view illustrated inFIG.14.FIG.16AandFIG.16Bare drawings for describing a structure of a first shielding member3aprovided in the protection element200of the second embodiment.FIG.16Ais a perspective view looking from a housing portion side, and theFIG.16Bis a perspective view looking from the fuse element side.FIG.17is a plan view of an inside of the housing portion of a first case6aprovided in the protection element200of the second embodiment looking from a second case6bside.

The first shielding member3ais interposed between the fuse element2and the first case6acontaining the housing portion60. “Fuse element side” refers to a side of the first shielding member3awhereon the fuse element2is disposed. “Housing portion side” refers to a side of the first shielding member3awhereon the first case6acontaining the housing portion60is disposed.

In the protection element200according to the second embodiment, the same members as those of the protective element100according to the first embodiment described above are denoted by the same reference signs, and descriptions thereof are omitted.

The protection element200according to the second embodiment illustrated inFIG.14differs from the protection element100according to the first embodiment in that it is included in two springs81, a spring guide hole82respectively provided to the first case6aand the second case6b, and a spring-receiving groove83respectively provided to the first shielding member3aand a second shielding member3b(seeFIG.16AandFIG.16B).

InFIG.14, the spring81disposed in contact with the first shielding member3ais pressing means for applying force in a rotation direction of the first shielding member3aagainst a second surface32of a plate-shaped part30included in the first shielding member3a. Furthermore, the spring81disposed in contact with the second shielding member3bis pressing means for applying force in a rotation direction of the second shielding member3bagainst the second surface32of the plate-shaped part30included in the second shielding member3b.

In the present embodiment, a case where the spring81is used as pressing means is described as an example; however, it is sufficient to apply force in a rotation direction of the shielding member against the second surface32of the plate-shaped part30as the pressing means-any known means capable of imparting elastic force may be used, and the pressing means is not limited to a spring.

As illustrated inFIG.14, the spring81that applies force in the rotation direction of the first shielding member3ais housed in a compressed state in the spring guide hole82provided in the first case6a. The spring81that applies force in the rotation direction of the second shielding member3bis housed in a compressed state in the spring guide hole82provided in the second case6b.

The spring guide hole82is substantially circular in a plan view, and is respectively provided at a center portion in a Y-direction on a first bottom surface68cof a concave portion68included in the first case6aand the second case6b(seeFIG.17). The spring guide hole82has a depth corresponding to a length of the spring81in a compressed state. The spring guide hole82expands and contracts the spring81along an inner wall surface of the spring guide hole82to expand and contract the spring81in a Z-direction with high precision.

The second surface32of the plate-shaped part30included in the first shielding member3aand the second shielding member3bis provided with the spring-receiving groove83wherein the end portions of each spring81in the expansion and contraction direction come into contact (seeFIG.16AandFIG.16B). The spring-receiving groove83is a concave portion having a planar shape coupling a semicircle and a rectangle wherein one side has a diameter of the semicircle, and is provided at a center portion in the Y-direction at an end edge32aof the second surface32in an X-direction.

A bottom surface of the spring-receiving groove83may be a flat surface, may be an inclined surface whose depth gradually increases toward a center portion of the first shielding member3aor the second shielding member3bin the X-direction, or may have a flat surface and the foregoing inclined surface formed continuously with the flat surface. When the bottom surface of the spring-receiving groove83has the foregoing inclined surface, the bottom surface of the spring-receiving groove83on the first shielding member3aor the second shielding member3bundergoing rotational movement moves closer to a plane perpendicular to the Z-direction in comparison to when it has a flat surface. Therefore, pressing force in the Z-direction due to a restoring force of the spring81may be applied more reliably and sufficiently to the second surface32of the plate-shaped part30on the first shielding member3aor the second shielding member3bundergoing rotational movement, which is preferable.

(Operation of the Protection Element)

Next, the operation of the protection element200will be described in a case where a current exceeding a rated current flows through the fuse element2in the protective element200according to the second embodiment.

When a current exceeding a rated current flows through the fuse element2of the protective element200of the present embodiment, the fuse element2fuses and an arc discharge is generated in the same manner as the protection element100according to the first embodiment.

In the protection element200of the present embodiment, pressure elevation in the housing portion60due to an arc discharge generated when the fuse element2fuses causes a first surface31on the plate-shaped part30included in the first shielding member3aand the second shielding member3bto be pressed in the same manner as the protection element100according to the first embodiment. In addition thereto, in the protection element200of the present embodiment, as illustrated inFIG.15, a restoring force of the compressed spring81presses the second surface32of the plate-shaped part30, and force is applied in the rotation direction of the first shielding member3aand the second shielding member3b. Thus, in the protection element200of the present embodiment, the first shielding member3aand the second shielding member3brotate around a rotation axis33at a rotational force stronger than the protection element100according to the first embodiment. Also, a first end edge31ais pressed onto a bottom surface of a shielding member housing groove34provided on an inner surface of the housing portion60in the same manner as the protection element100according to the first embodiment. Furthermore, a second end edge31bis housed in the concave portion68.

In the protection element200of the present embodiment, pressure elevation in the housing portion60due to an arc discharge generated when the fuse element2fuses causes the first surface31of the first shielding member3aand the second shielding member3bto be pressed in the same manner as the protection element100according to the first embodiment. In addition thereto, in the protection element200of the present embodiment, the spring81presses the second surface32of the plate-shaped part30, and force is applied in the rotation direction of the first shielding member3aand the second shielding member3b. Due to the synergistic effects thereof, as illustrated inFIG.15, the first shielding member3aand the second shielding member3beach rotate around the rotation axis33. As a result, the first shielding member3aand the second shielding member3bmore reliably block and divide the inside of the housing portion60at two locations in the X-direction. Accordingly, in the protection element200of the present embodiment, an arc discharge generated when the fuse element2fuses is more quickly suppressed (extinguished).

In the protection element200of the present embodiment, a case where there are two springs81are provided is described as an example; however, only one spring81need be provided.

Furthermore, in the protection element200of the present embodiment, a case where one spring81each is provided for applying force in the rotation direction against the first shielding member3aand the second shielding member3b, one spring guide hole82is provided at a center portion in the Y-direction on the first bottom surface68cof the concave portion68, and one spring-receiving groove83is provided at a center portion of the second surface32in the Y-direction is described as an example; however, the number of springs81and the positions of the spring guide hole82and the spring-receiving groove83are not limited to the foregoing example. For example, two springs each may be provided for applying force in the rotation direction against the first shielding member3aand/or the second shielding member3b, and two spring guide holes and spring-receiving grooves may be disposed symmetrically with respect to the center in the Y-direction. In this case, force is applied from the two springs in the rotation direction to both the first shielding member3aand the second shielding member3b.

Third Embodiment

(Protection Element)

FIG.18is a perspective view illustrating an entire structure of a protection element300of a third embodiment.FIG.19is an exploded perspective view illustrating the entire structure of the protection element300illustrated inFIG.18.FIG.20is a cross-section view of the protection element300of the third embodiment, cut along line B-B′ illustrated inFIG.18.FIG.21is a drawing for describing the operation of the protection element300of the third embodiment, and is a cross-section view of a position corresponding to the cross-section view illustrated inFIG.20.

In the protection element300according to the third embodiment, the same members as those of the protective element200according to the second embodiment described above are denoted by the same reference signs, and descriptions thereof are omitted.

The protection element300according to the third embodiment illustrated inFIG.18differs from the protection element200according to the second embodiment in that, as illustrated inFIG.19, it is provided with two heat generation members5, power supply wires54a,54b,55a, and55b, and power supply lead-out wires54and55; a heat generation member housing concave portion36is respectively provided for a first shielding member3aand a second shielding member3b; a notch76bwherein each power supply lead-out wire54and55is installed is provided on a first case6aand a second case6b; and a lead-out wire groove4bis provided on a cover4.

In the present embodiment, as illustrated inFIG.20, a case where two heat generation members5of a first heat generation member51and a second heat generation member56are provided is described as an example; however, only one of the two heat generation members5need be provided.

As illustrated inFIG.20, the first heat generation member51is installed on a first surface31of a plate-shaped part30of the first shielding member3a. Furthermore, the second heat generation member56is installed on the first surface31of the plate-shaped part30of the second shielding member3b. As illustrated inFIG.20, the first heat generation member51and the second heat generation member56are each disposed facing each other at a position in proximity to a cut portion23of a fuse element2. Also, the first heat generation member51and the second heat generation member56are disposed symmetrically in an X-direction with respect to the cut portion23. Therefore, the first heat generation member51and the second heat generation member56efficiently heat the cut portion23of the fuse element2.

Next, a structure of the first heat generation member51will be described usingFIG.22. A structure of the second heat generation member56is the same as that of the first heat generation member51; therefore, a description will be omitted.

FIG.22is a drawing for describing the structure of the first heat generation member51provided in the protection element300of the third embodiment,FIG.22(a)is a cross-section view looking from the X-direction,FIG.22(b)is a cross-section view looking from a Y-direction, andFIG.22(c)is a plan view.

As illustrated inFIG.22(a)toFIG.22(c), the first heat generation member51is a plate-shaped member. A width of the first heat generation member51in the X-direction is equal to or less than a width of the first shielding member3ain the X-direction. Furthermore, it is preferable that a width of the first heat generation member51in the Y-direction is wider than a width of the fuse element2in the Y-direction.

In the present embodiment, a case where the first heat generation member51is a plate-shaped member is described as an example; however, the heat generation member is not limited to a plate-shaped member, and it may be, for example, a wire having a meander pattern (meandering pattern).

The first heat generation member51has an insulated substrate51a, a heat generation unit51b, an insulating layer51c, an element-connecting electrode51d, and power supply wire electrodes51eand51f. The first heat generation member51has a function of heating the cut portion23of the fuse element2to cause it to soften. When an abnormality occurs in an external circuit serving as an energizing path for the protection element300and the energizing path needs to be interrupted, the first heat generation member51is energized by a current control element provided in the external circuit to generate heat. Furthermore, when the power supply wires54a,54b,55a, and55bfuse after the fuse element2is cut, a power supply to the first heat generation member51is interrupted, and heat generation of the first heat generation member51stops.

The insulated substrate51a, as illustrated inFIG.22(a)toFIG.22(c), has a substantially rectangular shape in a plan view wherein the long sides extend in the Y-direction.

A substrate having a known insulating property may be used as the insulated substrate51a, and examples thereof include those composed of alumina, glass ceramic, mullite, zirconia, and the like.

As illustrated inFIG.22(a)toFIG.22(c), the heat generation unit51bis formed on a surface of the insulated substrate51afacing the fuse element2(a lower surface inFIG.22(a)toFIG.22(c)). As illustrated inFIG.22(c), the heat generation unit51bis provided in a belt shape extending in the Y-direction along one long side edge portion of the insulated substrate51athat has a substantially rectangular shape in a plan view. A width of the heat generation unit51bin the X-direction and the Y-direction is determined as appropriate according to a width of the cut portion23in the X-direction and the Y-direction so that the cut portion23of the fuse element2may be efficiently heated. It is preferable that the heat generation unit51bis a resistive element composed of a conductive material that generates heat when energized via the power supply wires54aand54b. A material containing a metal such as nichrome, W, Mo, Ru, or the like may be given as an example of a material of the heat generation unit51b.

As illustrated inFIG.22(a)toFIG.22(c), the power supply wire electrodes51eand51fare provided at an end portion of the insulated substrate51ain the Y-direction, and one portion each is provided at a position overlapping both end portions51g,51gfacing each other across a center of the heat generation unit51bin a plan view. The power supply wire electrodes51eand51fare respectively electrically connected to both end portions51g,51gof the heat generation unit51b. The power supply wire electrodes51eand51fmay be formed of a known electrode material.

The power supply wire electrode51eis electrically connected to the power supply lead-out wire55via the power supply wire55a(seeFIG.19). The power supply wire electrode51fis electrically connected to the power supply lead-out wire54via the power supply wire54a(seeFIG.19).

When an abnormality occurs in an external circuit serving as an energizing path for the protection element300and the energizing path needs to be interrupted, the power supply wire electrodes51eand51fare for energizing the heat generation unit51bby means of a current control element provided in the external circuit.

As illustrated inFIG.22(a)toFIG.22(c), the insulating layer51cis provided on the heat generation unit51b. The insulating layer51cis provided at a center portion of the insulated substrate51ain the Y-direction so as to cover the heat generation unit51band a connection portion between the heat generation unit51band the power supply wire electrodes51eand51f. The insulating layer51cis not provided at an end portion of the insulated substrate51ain the Y-direction. As a result, one portion of the power supply wire electrodes51eand51fis not covered by the insulating layer51cand is exposed.

The insulating layer51cprotects the heat generation unit51b, efficiently transmits the heat generated by the heat generation unit51bto the fuse element2, and also seeks to insulate the heat generation unit51band the element-connecting electrode51d. The insulating layer51cmay be formed of a known insulating material, such as glass.

As illustrated inFIG.22(a)toFIG.22(c), the element-connecting electrode51dis provided at a position whereat at least one portion is overlapping the heat generation unit51bvia the insulating layer51c. The element-connecting electrode51dmay be formed of a known electrode material. The element-connecting electrode51dis electrically connected to the fuse element2.

In the first heat generation member51illustrated inFIG.22(a)toFIG.22(c), the heat generation unit51b, the insulating layer51c, the element-connecting electrode51d, and the power supply wire electrodes51eand51fare provided along one long side edge portion of the insulated substrate51athat has a substantially rectangular shape in a plan view; however, these need not be provided along both long side edge portions of the insulated substrate51a. In this case, for example, when electrically connecting the first heat generation member51and the power supply wires54aand55a, it is possible to prevent a reduction in yield due to mistaking the end portions on which the power supply wire electrodes51eand51fare not provided and the power supply wire electrodes51eand51f.

The first heat generation member51illustrated inFIG.22(a)toFIG.22(c)is disposed so that a surface of the element-connecting electrode51dside faces the fuse element2. Accordingly, the insulated substrate51ais not disposed between the heat generation unit51band the fuse element2. Therefore, heat generated by the heat generation unit51bis efficiently transmitted to the fuse element2in comparison to a case where the insulated substrate51ais disposed between the heat generation unit51band the fuse element2.

The first heat generation member51illustrated inFIG.22(a)toFIG.22(c)may be manufactured by the following method, for example. First, the insulated substrate51ais prepared. Furthermore, a paste-like composition containing a material serving as the heat generation unit51band a resin binder is produced. Thereafter, the foregoing composition is screen-printed on the insulated substrate51ato form a predetermined pattern, followed by firing. As a result, the heat generation unit51bis formed.

Next, the power supply wire electrodes51eand51fare formed by a known method, and are each electrically connected to both end portions51g,51gof the heat generation unit51b. Next, the insulating layer51cis formed by a known method, so that the insulating layer51ccovers the heat generation unit51b, and also covers a connection portion between the heat generation unit51band the power supply wire electrodes51eand51f.

Thereafter, the element-connecting electrode51dis formed on the insulating layer51cby a known method.

The first heat generation member51illustrated inFIG.22(a)toFIG.22(c)is obtained by the above process.

FIG.23is a drawing for describing another example of a heat generation member,FIG.23(a)is a cross-section view of a heat generation member52looking from the X-direction, andFIG.23(b)is a cross-section view of a center portion in the Y-direction of the heat generation member52illustrated inFIG.23(a)looking from the Y-direction.FIG.23(c)is a cross-section view of a heat generation member53looking from the X-direction, andFIG.23(d)is a cross-section of a center portion in the Y-direction of the heat generation member53illustrated inFIG.23(c)looking from the Y-direction.

In the protection element300of the present embodiment, the heat generation member52illustrated inFIG.23(a)andFIG.23(b)may be provided in place of the first heat generation member51(and/or the second heat generation member56) illustrated inFIG.22(a)toFIG.22(c). In the heat generation member52illustrated inFIG.23(a)andFIG.23(b), the same members as the first heat generation member51illustrated inFIG.22(a)toFIG.22(c)are denoted by the same reference signs, and descriptions thereof are omitted. The planar disposal of each member in the heat generation member52illustrated inFIG.23(a)andFIG.23is the same as the planar disposal of each member of the first heat generation member51illustrated inFIG.22(a)toFIG.22(c).

The heat generation member52illustrated inFIG.23(a)andFIG.23(b)has the insulated substrate51a, the heat generation unit51b, the insulating layer51c, the element-connecting electrode51d, and the power supply wire electrodes51eand51fin the same manner as the first heat generation member51illustrated inFIG.22(a)toFIG.22(c).

As illustrated inFIG.23(a)andFIG.23(b), the heat generation unit51bis formed on a surface of an opposite side to a surface of the insulated substrate51afacing the fuse element2(an upper surface inFIG.23(a)andFIG.23(b)).

As illustrated inFIG.23(a)andFIG.23(b), in the same manner as the first heat generation member51illustrated inFIG.22(a)toFIG.22(c), the power supply wire electrodes51eand51fare provided at an end portion of the insulated substrate51ain the Y-direction, and one portion is provided at a position overlapping both end portions51g,51g, respectively, of the heat generation unit51bin a plan view. The power supply wire electrodes51eand51fare respectively electrically connected to both end portions51g,51gof the heat generation unit51b.

As illustrated inFIG.23(a)andFIG.23(b), the insulating layer51cis provided on the heat generation unit51b. The insulating layer51cis provided at a center portion of the insulated substrate51ain the Y-direction so as to cover the heat generation unit51band a connection portion between the heat generation unit51band the power supply wire electrodes51eand51f. The insulating layer51cis not provided at an end portion of the insulated substrate51ain the Y-direction. As a result, one portion of the power supply wire electrodes51eand51fis not covered by the insulating layer51cand is exposed. The insulating layer51cprotects the heat generation unit51b.

As illustrated inFIG.23(a)andFIG.23(b), the element-connecting electrode51don the heat generation member52is formed on a surface of an opposite side to a side whereon the heat generation unit51bof the insulated substrate51ais provided, which is different to the first heat generation member51illustrated inFIG.22(a)toFIG.22(c). Accordingly, the element-connecting electrode51dis disposed facing the heat generation unit51bvia the insulated substrate51a. The element-connecting electrode51dis provided at a position whereat at least one portion is overlapping the heat generation unit51b. Furthermore, the element-connecting electrode51dis electrically connected to the fuse element2in the same manner as the first heat generation member51illustrated inFIG.22(a)toFIG.22(c).

In the protection element300of the present embodiment, the heat generation member53illustrated inFIG.23(c)andFIG.23(d)may be provided in place of the first heat generation member51(and/or the second heat generation member56) illustrated inFIG.22(a)toFIG.22(c). In the heat generation member53illustrated inFIG.23(c)andFIG.23(d), the same members as the first heat generation member51illustrated inFIG.22(a)andFIG.22(c)are denoted by the same reference signs, and descriptions thereof are omitted. The disposal of each member in the cross section of the center portion of the heat generation member53in the Y-direction illustrated inFIG.23(c)andFIG.23(d)looking from the Y-direction is the same as that of each member of the first heat generation member51illustrated inFIG.22(a)toFIG.22(c).

The heat generation member53illustrated inFIG.23(c)andFIG.23(d)has the insulated substrate51a, the heat generation unit51b, the insulating layer51c, the element-connecting electrode51d, and the power supply wire electrodes51eand51fin the same manner as the first heat generation member51illustrated inFIG.22(a)toFIG.22(c).

As illustrated inFIG.23(c), the heat generation unit51bis formed on a surface of the insulated substrate51afacing the fuse element2(a lower surface inFIG.23(c)andFIG.23(d)). As illustrated inFIG.23(c), the heat generation unit51bis provided in a belt shape extending in the Y-direction along one long side edge portion from one edge to another edge of the insulated substrate51athat has a substantially rectangular shape in a plan view.

As illustrated inFIG.23(c), the insulating layer51cis provided on the heat generation unit51b. The insulating layer51cis provided at a center portion of the insulated substrate51ain the Y-direction so as to cover a region excluding both end portions51g,51gof the heat generation unit51b. Accordingly, both end portions51g,51gof the heat generation unit51bare not covered by the insulating layer51cand are exposed.

As illustrated inFIG.23(c), the power supply wire electrodes51eand51fare provided at an end portion of the insulated substrate51ain the Y-direction, and overlap with both end portions51g,51g, respectively, of the heat generation unit51bin a plan view. As a result, the power supply wire electrodes51eand51fare electrically connected to the heat generation unit51b.

As illustrated inFIG.23(c), the element-connecting electrode51dis provided at a region on the insulating layer51cexcluding a region whereon the power supply wire electrodes51eand51fare provided. As illustrated inFIG.23(c), the element-connecting electrode51dis disposed separated from the power supply wire electrodes51eand51f. The element-connecting electrode51dis provided at a position on the insulating layer51cwhereat at least one portion is overlapping the heat generation unit51b.

FIG.24is an enlarged drawing for describing one portion of the protection element300of the third embodiment, and is a perspective view illustrating the fuse element2, a first terminal61, a second terminal62, the first heat generation member51, the second heat generation member56, the power supply wires54a,54b,55a, and55b, and the power supply lead-out wires54and55.

As illustrated inFIG.24, the first heat generation member51is electrically connected to the power supply wires54aand55a. Furthermore, the second heat generation member56is electrically connected to the power supply wires54band55b. Furthermore, in the present embodiment, as illustrated inFIG.24, the power supply wire54aand the power supply wire54bare electrically connected to the power supply lead-out wire54, and the power supply wire55aand the power supply wire55bare electrically connected to the power supply lead-out wire55.

In the present embodiment, a case where the power supply wire54aand the power supply wire54bare electrically connected to one power supply lead-out wire54is described as an example; however, the power supply wire54aand the power supply wire54bmay each be connected to a separate power supply lead-out wire. Furthermore, a case where the power supply wire55aand the power supply wire55bare electrically connected to one power supply lead-out wire55is described as an example; however, the power supply wire55aand the power supply wire55bmay be respectively connected to a separate power supply lead-out wire.

In the present embodiment, the power supply wires54a,54b,55a, and55bare belt-shaped, and each is installed in a side surface concave portion77aserving as a side surface vent77by integrating the first case6aand the second case6b(seeFIG.19). The power supply wires54a,54b,55a, and55bmay be formed of a known conductive wiring material. In the present embodiment, a case where the power supply wires54a,54b,55a, and55bare belt-shaped is given as an example; however, each power supply wire is not limited to being belt-shaped-they may be line-shaped.

Furthermore, the power supply lead-out wires54and55are formed of a conductive wiring material that is circular in a cross section view. The power supply lead-out wires54and55are disposed symmetrically with respect to the fuse element2. The power supply lead-out wires54and55are respectively bent to bend in a U-shape in a plan view.

The two bent portions54cand55cincluded in the power supply lead-out wires54and55are respectively installed in the notch76bprovided at an edge portion along the first case6aand the second case6bin the X-direction (seeFIG.19). In the present embodiment, the power supply lead-out wires54and55have the bent portions54cand55c; therefore, even if external stress is applied to the power supply lead-out wires54and55, the external stress is transmitted to the power supply wires54a,54b,55a, and55b, and it is possible to control a defect wherein the electrical connection between the first heat generation member51or the second heat generation member56and the power supply lines54a,54b,55a, and55bis broken.

The notch76bis formed over an entire length (thickness) of an end member72in the X-direction.

Furthermore, each end portion side is exposed from the cover4beyond the bent portions54cand55cof the power supply lead-out wires54and55while in a state of being held in the lead-out wire groove4bprovided in the cover4(seeFIG.18andFIG.19). Two lead-out wire grooves4bare formed, each at the respective opening portion on both sides of the cover4so as to face each other in a diametrical direction. A width of the lead-out wire groove4bin a circumferential direction of the cover4may be determined as appropriate according to a diameter of the power supply lead-out wires54and55.

FIG.25AtoFIG.25Bare drawings for describing the structure of the first shielding member3aprovided in the protection element300of the third embodiment.FIG.25Ais a perspective view looking from the housing portion side, andFIG.25Bis a perspective view looking from the fuse element2side.

The first shielding member3aprovided in the protection element300of the third embodiment has a heat generation member housing concave portion36wherein the heat generation member51is housed. The heat generation member housing concave portion36, as illustrated inFIG.25B, is provided on the first surface31of the plate-shaped part30in proximity to a first end edge31a.

The first shielding member3ais interposed between the fuse element2and the first case6acontaining the housing portion60. “Fuse element side” refers to a side of the first shielding member3awhereon the fuse element2is disposed. “Housing portion side” refers to a side of the first shielding member3awhereon the first case6acontaining the housing portion60is disposed.

A width of the heat generation member housing concave portion36in the X-direction is determined according to a width of the heat generation member51in the X-direction. Furthermore, a width of the heat generation member housing concave portion36in the Y-direction is determined according to a width of the heat generation member51in the Y-direction.

A depth (length in a Z-direction) of the heat generation member housing concave portion36is set to a depth wherein the top of the plate-shaped part30and the top of the heat generation member51are on the same plane in a state where the heat generation member51is installed in the heat generation member housing concave portion36. In the protection element300of the third embodiment, as illustrated inFIG.20, it is preferable that the first surface31of the plate-shaped part30and the heat generation member51are disposed in contact with the fuse element2. As a result, the heat generation member51may efficiently heat the cut portion23, and may interrupt the current path in a short time.

(Method of Manufacturing the Protection Element)

Next, a method of manufacturing the protection element300of the present embodiment will be described with reference to drawings.

First, a member wherein the fuse element2is integrated with the first terminal61and the second terminal62is created (seeFIG.7) to manufacture the protection element300of the present embodiment in the same manner as the protection element100according to the first embodiment.

Furthermore, as illustrated inFIG.26A, a linear conductive member54dserving as the power supply lead-out wire54is prepared, and the power supply wires54aand54bare each connected by soldering. Furthermore, a linear conductive member55dserving as the power supply lead-out wire55is prepared, and the power supply wires55aand55bare each connected by soldering.

Also, the power supply wire55ais soldered to the power supply wire electrode51eof the first heat generation member51, and the power supply wire54ais soldered to the power supply wire electrode51f. Furthermore, as illustrated in FIG.26A, the power supply wire55bis soldered to the power supply wire electrode51eof the second heat generation member56, and the power supply wire54bis soldered to the power supply wire electrode51f.

Furthermore, the first shielding member3ais installed inside the concave portion68of the first case6a. Furthermore, the second shielding member3bis installed inside the concave portion68of the second case6b.

Thereafter, as illustrated inFIG.26A, a member wherein the fuse element2, the first terminal61, the second terminal62, the first heat generation member51, the second heat generation member56, the power supply wires54a,54b,55a, and55b, and the conductive members54dand55dare integrated is installed on the second case6bwherein the second shielding member3bis installed. During this, the second heat generation member56is housed in the heat generation member housing concave portion36of the second shielding member3b.

Also, as illustrated inFIG.26(b), the first case6a, wherein the first shielding member3ais installed, is installed on the second case6b, wherein the foregoing integrated member is installed. During this, the fitting concave portion63included in the first case6aand the fitting convex portion67included in the second case6bare fitted together, and the fitting convex portion67included in the first case6aand the fitting concave portion63included in the second case6bare fitted together.

As illustrated inFIG.26B, the first case6ais installed on the second case6b, forming a second buffer concave portion75, the side surface vent77, a first adhesive inlet78, and a second adhesive inlet76. As a result, the power supply wires54a,54b,55a, and55bare in a state passing through each side surface vent77and connected to the conductive members54dand55ddisposed outside the case6. Furthermore, as illustrated inFIG.20, a state is formed where one insertion hole64houses a first end portion21of the fuse element2, another insertion hole64houses a second end portion22of the fuse element2, and one portion of the first terminal61and one portion of the second terminal62connected to the fuse element2are exposed to the outside of the case6.

Next, the first case6aand the second case6bare housed in the cover4in an integrated state. As a result, the cover4covers the end member72forming a side surface along the case6in the X-direction, a first buffer concave portion73, and the second buffer concave portion75, and also fixes the first case6aand the second case6b.

Thereafter, the conductive members54dand55dare fitted into the respective lead-out wire grooves4bprovided in the cover4and bent outward at a substantial right angle. As a result, the two bent portions54cand55c(seeFIG.24) are formed in the respective conductive members54dand55dto form the power supply lead-out wires54and55.

Thereafter, an adhesive is injected into an inclined surface4aof the cover4, the first adhesive inlet78, and the second adhesive inlet76, respectively. As a result, the inside of the cover4is sealed and an outer surface of the case6and an inner surface of the cover4seal a spatial region composed of the housing portion60and an internal pressure buffer space71.

The protection element300of the present embodiment is obtained by the foregoing process.

(Operation of the Protection Element)

Next, the operation of the protection element300will be described in a case where a current exceeding a rated current flows through the fuse element2in the protective element300according to the third embodiment.

When a current exceeding a rated current flows through the fuse element2of the protection element300of the present embodiment, the fuse element2itself generates heat and the fuse element2is fused.

In the protection element300of the present embodiment, pressure elevation in the housing portion60due to an arc discharge generated when the fuse element2fuses causes, in the same manner as the protection element200according to the second embodiment, the first surface31on the plate-shaped part30included in the first shielding member3aand the second shielding member3bto be pressed, and, as illustrated inFIG.21, a restoring force of a compressed spring81presses a second surface32of the plate-shaped part30and force is applied in a rotation direction of the first shielding member3aand the second shielding member3b. Thus, in the protection element300of the present embodiment, the first shielding member3aand the second shielding member3brotate around a rotation axis33. Also, the first end edge31ais pressed onto the bottom surface of a shielding member housing groove34provided on an inner surface of the housing portion60. Furthermore, a second end edge31bis housed in the concave portion68.

In the protection element300of the present embodiment, in the same manner as the protection element200according to the second embodiment, pressure elevation in the housing portion60due to an arc discharge generated when the fuse element2fuses causes the first surface31of the first shielding member3aand the second shielding member3bto be pressed, and the spring81presses the second surface32of the plate-shaped part30and force is applied in the rotation direction of the first shielding member3aand the second shielding member3b. Due to the synergistic effects thereof, as illustrated inFIG.21, the first shielding member3aand the second shielding member3beach rotate around the rotation axis33. As a result, the first shielding member3aand the second shielding member3bmore reliably block and divide the inside of the housing portion60at two locations in the X-direction. Accordingly, in the protection element300of the present embodiment, an arc discharge generated when the fuse element2fuses is quickly suppressed (extinguished).

Furthermore, in the protection element300of the present embodiment, the first heat generation member51and the second heat generation member56for heating the fuse element2are disposed in contact with the cut portion23of the fuse element2. Accordingly, when an abnormality occurs in an external circuit serving as an energizing path for the protection element300and the energizing path needs to be interrupted, the first heat generation member51and the second heat generation member56are energized by a current control element provided in the external circuit to generate heat, the cut portion23is efficiently heated, and the current path may be interrupted in a short time.

Furthermore, after the fuse element2is cut, the power supply wires54a,54b,55a, and55bare cut by the rotation of the first shielding member3aand the second shielding member3band melting of a solder connection of the power supply wire electrodes51eand51fdue to the heat generated by the first heat generation member51and the second heat generation member56. As a result, a power supply to the first heat generation member51and the second heat generation member56is interrupted, and the heat generation of the first heat generation member51and the second heat generation member56is stopped. Thus, the protection element300of the present embodiment has excellent safety.

Other Example

The protection element of the present invention is not limited to the protection element of the first embodiment and the second embodiment described above.

For example, in the protection element100of the first embodiment and the protection element200of the second embodiment described above, a case where the cut portion23is disposed close to the center of the fuse element2in the X-direction, the first shielding member3aand the second shielding member3bhave the same shape, and the first case6aand the second case6bhave the same shape is described as an example; however, the position of the cut portion need not be close to the center of the fuse element in the X-direction. In this case, the first shielding member3aand the second shielding member3bhave different lengths in the X-direction. Furthermore, the first case6ahas a housing portion shape corresponding to the shape of the first shielding member3a, and the second case6bhas a housing portion shape corresponding to the shape of the second shielding member3b.

REFERENCE SIGNS LIST

2Fuse element,3Shielding member,3aFirst shielding member,3bSecond shielding member,4Cover,4aInclined surface,4bLead-out wire groove,5,52,53Heat generation member,6Case,6aFirst case,6bSecond case,21First end portion,22Second end portion,23Cut portion (constricted portion),24aFirst bent portion,24bSecond bent portion,25First connecting unit,26Second connecting unit,30Plate-shaped part,33aContact position,30aFirst area,30bSecond area,31First surface,31a,32aFirst end edge,31bSecond end edge,32Second surface,32bSecond end surface,33Rotation axis,34Shielding member housing groove,35Leak prevention groove,36Heat generation member housing concave portion,38Convex portion,41First end,42Second end,51First heat generation member,51aInsulated substrate,51bHeat generation unit,51cInsulating layer,51dElement-connecting electrode,51e,51fPower supply wire electrode,56Second heat generation member,54,55Power supply lead-out wire,54a,54b,55a,55bPower supply wire,60Housing portion,61First terminal,61a,62aExternal terminal hole,61c,62cFlange portion,62Second terminal,63Fitting concave portion,64Insertion hole,64aInsertion hole-forming surface,64bTerminal-mounting surface,65Fuse element-mounting surface,66Guide hole,67Fitting convex portion,68Concave portion,68aFirst wall surface,68bSecond wall surface,68cFirst bottom surface,68dSecond bottom surface,69Bottom surface vent,70Joining surface,71Internal pressure buffer space,72End member,73First buffer concave portion,74Second concave portion,75Second buffer concave portion,76Second adhesive inlet,76a,76bNotch,77Side surface vent,77aSide surface concave portion,78First adhesive inlet,78aNotch,81Spring,82Spring guide hole,83Spring-receiving groove,100,200,300Protection element