WO2018159283A1 - Fuse element - Google Patents

Abstract

Provided is a fuse element that is adaptive for a high-rated large current application, has excellent shock resistance when a current is cut off, and is capable of preventing a case from falling off. This fuse element is provided with: a base member 2; a cover member 3 that fits to the base member 2 and covers a surface 2a of the base member 2; and a fuse component 5 that is mounted on the surface 2a of the base member 2, wherein side walls 11, 22 in which openings 17, 28 are formed are provided to one of the base member 2 and the cover member 3 so as to be erected in the surface direction of the surface 2a of the base member 2, and projected fitting parts 18, 29 are provided to the other so as to project in the surface direction parallel to the surface 2a of the base member 2 and so as to fit into the openings 17, 28 of the side walls 11, 22.

Description

Fuse element

This technology is mounted on the current path and relates to a fuse element that fuses the fuse element due to self-heating when a current exceeding the rating flows, and cuts off the current path. It relates to an element. The present application includes Japanese Patent Application No. 2017-037574 filed on February 28, 2017 in Japan, Japanese Patent Application No. 2017-082025 filed on April 18, 2017 in Japan, And claims the priority on the basis of Japanese Patent Application No. 2018-018293 filed on February 5, 2018 in Japan, and these applications are incorporated herein by reference. The

Conventionally, a fuse element that melts by self-heating when a current exceeding the rating flows and interrupts the current path has been used. As the fuse element, for example, a holder-fixed fuse in which solder is enclosed in a glass tube, a chip fuse in which an Ag electrode is printed on the surface of a ceramic substrate, or a screw fixing in which a part of a copper electrode is thinned and incorporated in a plastic case or Plug-in fuses are often used.

However, it has been pointed out that the above-mentioned existing fuse elements cannot be surface-mounted by reflow, have a low current rating, and if the rating is increased by increasing the size, the quick disconnection property is inferior.

In addition, when assuming a fast-acting fuse element for reflow mounting, generally, a high melting point solder containing Pb having a melting point of 300 ° C. or higher is preferable for the fuse element in terms of fusing characteristics so as not to melt by the heat of reflow. However, in the RoHS directive and the like, the use of Pb-containing solder is only limitedly recognized, and it is considered that the demand for Pb-free solder will increase in the future.

In other words, the fuse element can be surface-mounted by reflow and has excellent mountability to the fuse element, it can handle a large current by raising its rating, and the current path is quickly interrupted when overcurrent exceeds the rating. It is required to have fast fusing properties.

Therefore, a fuse element has been proposed in which a fuse element is mounted on an insulating substrate having first and second electrodes across the first and second electrodes (see Document 1).

When the fuse element described in Document 1 is surface-mounted on a circuit board, the first and second electrodes on which the fuse element is mounted are incorporated in a part of the current path, and a current having a value higher than the rating is obtained. When it flows, the fuse element melts due to self-heating and interrupts the current path.

JP 2014-209467 A

Here, the application of this type of fuse element extends from electronic devices to industrial machines, electric bicycles, electric bikes, cars and other high-current applications. For this reason, with the increase in capacity and rating of mounted electronic devices and battery packs, the fuse element is required to further improve the current rating.

In order to increase the current rating, it is effective to reduce the resistance by increasing the size of the fuse element. However, when a voltage exceeding the rating is applied and an overcurrent flows, the fuse element melts while arc discharge occurs. Therefore, when the fuse element is increased in size, the impact caused by arc discharge increases in proportion to the increase in size.

Also, with the improvement in current rating, the temperature at the time of self-heating cutoff due to overcurrent increases and the thermal effect on the element housing also increases.

For this reason, the case member attached to the insulating substrate and protecting the fuse element cannot withstand the heat effect at the time of current interruption and the rapidly increasing internal pressure, and may be damaged, or may be displaced from the insulating substrate or fall off. Further, there is a possibility that the dropped case may collide with surrounding members, or unforeseen damage such as a short circuit may occur due to the melted and adhered fuse element.

Current countermeasures to quickly stop arc discharge and shut off the circuit include a hollow case filled with an arc extinguishing material, or a high voltage compatible current that generates a time lag by spirally wrapping a fuse element around the heat dissipation material Fuses have also been proposed. However, conventional high-voltage current fuses require complicated materials and processing processes, such as arc-quenching material encapsulation and spiral fuse manufacturing, and the fuse element is downsized and current rating is increased. It is disadvantageous in terms.

Therefore, an object of the present technology is to provide a fuse element that is excellent in impact resistance at the time of interruption of current and can prevent a case from dropping in a fuse element that can be used for a high rated and large current application.

In order to solve the above-described problem, a fuse element according to an embodiment of the present technology includes a base member, a cover member that is fitted to the base member and covers a surface of the base member, and between the base member and the cover member. The base member and the cover member are each provided with a side wall that intersects the surface direction of the surface of the base member and has an opening. On the other side, there is provided a fitting convex portion that projects outward from a surface intersecting the surface of the base member and is fitted into the opening of the side wall.

In addition, a fuse element to which the present technology is applied includes a base member, a cover member that is fitted to the base member and covers the surface of the base member, and a fuse that is disposed between the base member and the cover member. The base member and the cover member are made of a nylon plastic material.

According to the present technology, the fuse element is configured such that when the fitting protrusion of the cover member is fitted into the opening of the base member, the fuse element is self-heated and interrupted by arc discharge due to overcurrent. Even when pressure is suddenly applied to the upper surface of the base member, the opening and the fitting convex portion are in contact with each other, so that the resistance to the pressure above the surface of the base member is improved, and the cover member is the base member. Can be prevented from coming off.

FIG. 1 is an external perspective view showing the fuse element from the cover member side. FIG. 2 is an external perspective view showing the fuse element from the base member side. FIG. 3 is an external perspective view showing the fuse element from the cover member side. 4A is an external perspective view showing the fuse element from the front surface side, and FIG. 4B is an external perspective view showing the fuse element from the back surface side. FIG. 5 is an external perspective view showing a state in which the fuse element is mounted on the base member. FIG. 6 is an external perspective view showing a state in which the fuse element is mounted on the base member. FIG. 7 is an external perspective view showing the base member from the first side wall side. FIG. 8 is an external perspective view showing the base member from the back side. FIG. 9 is an external perspective view showing the base member from the first fitting convex portion side. FIG. 10 is an external perspective view showing the cover member from the top surface side. FIG. 11 is an external perspective view showing the inside of the cover member. FIG. 12 is an external perspective view showing the cover member from the second side wall side. FIG. 13 is a cross-sectional view of a fuse element in which a deformation restricting portion is formed. FIG. 14 is a circuit diagram of the fuse element, where (A) shows before the fuse element is blown and (B) shows after the fuse element is blown. 15A and 15B are diagrams showing a fuse element provided with a heating element, where FIG. 15A is a plan view and FIG. 15B is a cross-sectional view. FIG. 16 is a circuit diagram of the fuse element, where (A) shows before the fuse element is blown and (B) shows after the fuse element is blown. 17A is a plan view showing the fuse element from the cover member side, FIG. 17B is a side view of the fuse element, FIG. 17C is a rear view of the fuse element, and FIG. FIG. 17D is a front view of the fuse element, and FIG. 17E is a rear view showing the fuse element from the base member side. FIG. 18 is an external perspective view showing the base member from the first side wall side. FIG. 19 is an external perspective view showing the base member from the first fitting convex portion side. FIG. 20 is an external perspective view showing the back surface of the base member from the first side wall side. FIG. 21 is an external perspective view showing the back surface of the base member from the first fitting convex portion side. 22A is a plan view of the base member, FIG. 22B is a side view of the base member, FIG. 22C is a rear view of the base member, and FIG. 22D is the base member. FIG. 22E is a rear view of the base member. FIG. 23 is an external perspective view showing the cover member from the second fitting convex portion side. FIG. 24 is an external perspective view showing the cover member from the second side wall side. FIG. 25 is an external perspective view showing the inner surface of the cover member from the second fitting convex portion side. FIG. 26 is an external perspective view showing the inner surface of the cover member from the second side wall side. 27A is a plan view of the cover member, FIG. 27B is a side view of the cover member, FIG. 27C is a rear view of the cover member, and FIG. 27D is a cover member. FIG. 27E is a rear view of the cover member. FIG. 28 is a cross-sectional view showing a state where the first fitting claw portion and the second convex surface portion, and the second fitting claw portion and the first convex surface portion are locked with each other.

Hereinafter, the fuse element to which the present technology is applied will be described in detail with reference to the drawings. In addition, this technique is not limited only to the following embodiment, Of course, a various change is possible in the range which does not deviate from the summary of this technique. Further, the drawings are schematic, and the ratio of each dimension may be different from the actual one. Specific dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[Fuse element]
The fuse element 1 according to the present invention realizes a small and highly rated fuse element, and has a resistance value of 0 while having a small plane size of 3 to 5 mm × 5 to 10 mm and a height of 2 to 5 mm. .2 to 1mΩ, 50 to 150A rating and higher rating. Of course, the present invention can be applied to fuse elements having all sizes, resistance values, and current ratings.

The fuse element 1 according to the present invention includes a base member 2 and a cover member 3 covering the surface 2a of the base member 2 as shown in FIGS. The base member 2 and the cover member 3 constitute an element housing 4 by fitting with each other. 1 is an external perspective view showing the fuse element 1 from the cover member 3 side, FIG. 2 is an external perspective view showing the fuse element 1 from the back side of the base member 2, and FIG. 3 covers the fuse element 1. It is an external appearance perspective view shown from the member 3 side.

The fuse element 5 is mounted on the base member 2. The fuse element 5 is formed in a substantially rectangular plate shape as shown in FIGS. 4A and 4B, for example, and is bent on both sides in the energization direction along the side surface of the base member 2, As shown in FIG. 6, the base member 2 can be fitted onto the surface 2 a. Further, the fuse element 5 has terminal portions 5a and 5b which are extended to the outside and connected to connection electrodes of an external circuit (not shown). The fuse element 5 is sandwiched between a pair of upper and lower base members 2 and a cover member 3, and a pair of terminal portions 5 a and 5 b are led out of the element housing 4. When the fuse element 1 is mounted on an external circuit board, the terminal portions 5a and 5b of the fuse element 5 are connected to connection electrodes of the external circuit and are incorporated in the current path of the external circuit. In the fuse element 1, when a current exceeding the rating is applied, the fuse element 5 is melted by self-heating and interrupts the current path of the external circuit. A specific configuration of the fuse element 5 will be described in detail later.

[Base member]
The base member 2 is formed of an insulating member such as engineering plastic, alumina, glass ceramics, mullite, zirconia. The base member is manufactured by a manufacturing method corresponding to the material, such as molding or powder molding. As shown in FIG. 7 to FIG. 9, the base member 2 has the fuse element 5 mounted on the surface 2a and intersects with the surface direction of the surface 2a on one side edge side. The 1st side wall 11 which comprises is erected. 7 is an external perspective view showing the base member 2 from the first side wall 11 side, FIG. 8 is an external perspective view showing the base member 2 from the back surface side, and FIG. 9 shows the base member 2 as the first side wall. It is an external appearance perspective view shown from the fitting convex part 18 side.

The base member 2 is formed in a substantially rectangular plate shape, and the fuse element 5 is mounted with the width direction as the energization direction. In addition, the base member 2 has a groove portion 12 formed substantially in the width direction in the length direction. The base member 2 holds the fuse element 5 together with the cover member 3 on both sides of the groove 12. Thereby, the fuse element 5 is opposed to the groove portion 12 in the width direction orthogonal to the energizing direction, and the high heat conduction portion 14 sandwiched between the base member 2 and the cover member 3 and the low heat conduction portion 15 opposite to the groove portion 12 are provided. It is formed.

The high heat conducting portion 14 is sandwiched between the base member 2 and the cover member 3 so that the heat dissipation is relatively high in the plane of the fuse element 5, and the heat generated by the overcurrent is externally transmitted through the base member 2 and the cover member 3. Thus, the temperature rise can be suppressed, and overheating of the terminal portions 5a and 5b can be suppressed. The low thermal conductive portion 15 faces the groove portion 12 so as not to be in thermal contact with the base member 2 and the cover member 3 and is brought into contact with air having a lower thermal conductivity than the base member 2 and the cover member 3. In the surface of the element 5, heat dissipation is relatively low, and a fusing part is formed by fusing when heat generated by overcurrent is concentrated. In addition, the high heat conductive part 14 should just be in thermal contact with the base member 2 and the cover member 3, and in addition to being in direct contact with the base member 2 and the cover member 3, it is in contact via a member having thermal conductivity. May be.

A positioning wall 16 for positioning the fuse element 5 is formed at the end of the groove 12 on the first side wall 11 side. The positioning wall 16 is erected on the surface 2 a of the base member 2 from the groove portion 12, and determines the mounting position on the base member 2 by abutting one side surface of the fuse element 5.

[adhesive]
The fuse element 1 may connect the fuse element 5 to the base member 2 or the base member 2 and the cover member 3 with an adhesive (not shown). The adhesive is provided at a portion other than the groove 12 on the surface 2 a of the base member 2. As a result, the fuse element 1 has improved adhesion between the base member 2 or the base member 2 and the cover member 3 and the high thermal conductive portion 14 of the fuse element 5 via the adhesive, and can transfer heat more efficiently. .

Any known adhesive can be used as the adhesive, but it is preferable to have high thermal conductivity in order to promote heat dissipation of the fuse element 5 (for example, KJR-9086, manufactured by Shin-Etsu Chemical Co., Ltd., SX720: manufactured by Cemedine Co., Ltd., SX1010: manufactured by Cemedine Co., Ltd.). Further, as the adhesive, a conductive adhesive in which conductive particles are contained in a binder resin may be used. Even when a conductive adhesive is used as the adhesive, the adhesiveness between the base member 2 or the base member 2 and the cover member 3 and the fuse element 5 is improved, and the heat of the high heat conducting portion 14 is efficiently passed through the conductive particles. The base member 2 or the base member 2 and the cover member 3 can be transmitted well. Moreover, you may connect with solder instead of an adhesive agent.

A first side wall 11 is provided on one side edge side of the base member 2 so as to intersect with the surface direction of the surface 2 a of the base member 2, and preferably in a direction substantially perpendicular to the element member 4. Is formed. The first side wall 11 has a fitting recess 11a formed therein, and a first opening 17 into which a second fitting projection 29 formed on the cover member 3 described later is fitted in the fitting recess 11a, and An abutting surface 11 b that is continuous with the first opening 17 and abuts on the second fitting convex portion 29 inserted into the first opening 17 is formed.

Further, the other side edge opposite to the one side edge provided with the first side wall 11 of the base member 2 projects outward from a surface intersecting the surface 2a of the base member 2, and will be described later. A first fitting protrusion 18 that fits into a second opening 28 formed in the second side wall 22 formed in the cover member 3, and a base member on both sides of the first fitting protrusion 18. The first and second locking pieces 19a and 19b are formed so as to protrude outward from the surface intersecting the surface 2a of the second surface and locked to the second opening 28. The first fitting projection 18 preferably projects outward along a plane parallel to the surface 2 a of the base member 2.

[Cover member]
The cover member 3 covering the surface 2a of the base member 2 can be formed by the same material and the same manufacturing method as the base member 2. As shown in FIGS. 10 to 12, the cover member 3 includes a second side wall 22 constituting a side surface facing the first side wall 11 of the element housing 4 and a terminal portion provided in the energizing direction of the fuse element 5. 5a and 5b have third and fourth side walls 23 and 24 that are exposed to the outside, and a top surface portion 25 that constitutes the top surface of the element housing 4. 10 is an external perspective view showing the cover member 3 from the top surface 25 side, FIG. 11 is an external perspective view showing the inside of the cover member 3, and FIG. 12 shows the cover member 3 on the second side wall 22 side. FIG.

The inner surface 25 a of the top surface 25 of the cover member 3 is formed with a groove portion 26 in the longitudinal direction at the approximate center in the width direction, like the base member 2. The cover member 3 sandwiches the high heat conduction portion 14 of the fuse element 5 together with the base member 2 on both sides of the groove portion 26.

Also, a positioning wall 27 for positioning the fuse element 5 together with the positioning wall 16 is formed at the end of the groove portion 26 on the second side wall 22 side. The positioning wall 27 is erected on the inner surface 25 a of the top surface 25 of the cover member 3 from the groove portion 26, and determines the mounting position on the base member 2 by abutting the other side surface of the fuse element 5.

On one side edge side of the cover member 3, a second side wall 22 that stands up in a direction intersecting, preferably substantially perpendicular to the surface direction of the surface 2 a of the base member 2 and constituting the side surface of the element housing 4. Is formed. The second side wall 22 is formed with a fitting recess 22a, and in the fitting recess 22a, a second opening 28 in which the first fitting protrusion 18 formed on the base member 2 is fitted, and A contact surface 22b is formed which is continuous with the second opening 28 and contacts the first fitting convex portion 18 inserted into the second opening 28.

Further, the other side edge opposite to the one side edge provided with the second side wall 22 of the cover member 3 projects outward from the surface intersecting the surface direction of the surface 2a of the base member 2, and is described above. The surface of the base member 2 on both sides of the second fitting convex portion 29 and the second fitting convex portion 29 fitted into the first opening 17 formed in the first side wall 11 of the base member 2. 3rd and 4th latching pieces 30a and 30b which protrude outward from the surface which cross | intersects the surface of 2a, and are latched by the 1st opening part 17 are formed. The second fitting convex portion 29 preferably projects outward along a plane parallel to the surface 2 a of the base member 2.

[Opening / Fitting Protrusion / Locking Piece]
In the fuse element 1, the fuse element 5 is mounted on the surface 2 a of the base member 2, and then the cover member 3 is assembled to the base member 2 to form the element housing 4. At this time, in the fuse element 1, the second fitting protrusion 29 formed in the cover member 3 is fitted into the first opening 17 formed in the first side wall 11 of the base member 2, and The first fitting protrusion 18 formed in the base member 2 is fitted into the second opening 28 formed in the second side wall 22 of the cover member 3.

In the fuse element 1, the second fitting convex portion 29 of the cover member 3 is fitted into the first opening 17 of the base member 2, whereby the contact surface 11 b of the fitting concave portion 11 a is second fitted. It contacts the upper surface of the convex part 29 (FIG. 1). As a result, when the fuse element 5 is cut off by self-heat generation with arc discharge due to overcurrent, even if a sudden pressure is applied to the cover member 3 above the surface 2 a of the base member 2, it continues to the first opening 17. By pressing the second fitting convex portion 29 with the abutting contact surface 11b, the resistance against the pressure above the surface 2a of the base member 2 is improved, and the cover member 3 is prevented from being detached from the base member 2. be able to.

Similarly, in the fuse element 1, the first fitting protrusion 18 of the base member 2 is fitted into the second opening 28 of the cover member 3, so that the contact surface 22 b of the fitting depression 22 a is first. It contacts the lower surface of the fitting projection 18 (FIG. 3). As a result, the contact surface 22b continuous with the second opening 28 is pressed by the first fitting convex portion 18, whereby the resistance to the pressure above the surface 2a of the base member 2 is improved and the cover member 3 is The release from the base member 2 can be prevented.

Accordingly, the fuse element 1 is provided with an opening in at least one of the base member 2 and the cover member 3 and a fitting convex portion on the other, thereby improving the resistance to pressure above the surface 2a of the base member 2. However, it is preferable that the cover member 3 is more reliably removed from the base member 2 by providing the base member 2 and the cover member 3 with an opening and a fitting convex portion so as to be fitted to each other. It can be prevented from coming off.

Here, the first opening 17 has a rectangular shape in which the width direction of the base member 2 is the length direction, and the first side wall 11 is also formed thick so that the second fitting protrusion is formed. The contact surface 11 b that holds the portion 29 also has a width corresponding to the thickness of the first side wall 11. Similarly, the second opening 28 has a rectangular shape in which the width direction of the base member 2 is the length direction, and the second side wall 22 is also formed thick so that the first fitting protrusions are formed. The contact surface 22b pressed by the portion 18 also has a width corresponding to the thickness of the second side wall 22.

As shown in FIG. 10, the second fitting convex portion 29 fitted into the first opening portion 17 projects in the surface direction of the surface 2 a of the base member 2, and the first opening portion of the first side wall 11. 17 to be fitted. The second fitting convex portion 29 is fitted to the first opening 17 from the tip to the base portion 29a and is in contact with the contact surface 11b. Similarly, as shown in FIG. 7, the first fitting convex portion 18 that fits into the second opening 28 protrudes in the surface direction of the surface 2 a of the base member 2, and the second fitting of the second side wall 22. It is fitted by being inserted into the opening 28. Then, the first fitting convex portion 18 is fitted to the second opening 28 from the tip to the base portion 18a, and is in contact with the contact surface 22b.

Further, the second fitting convex portion 29 has a width in the width direction intersecting the insertion direction to the first opening 17 wider than the length in the insertion direction in the surface direction of the surface 2 a of the base member 2. The contact surface between the second fitting convex portion 29 and the contact surface 11 b is also wider in the width direction than the insertion direction of the first opening portion 17. Similarly, in the surface direction of the surface 2a of the base member 2, the first fitting convex portion 18 has a width in the width direction that intersects the insertion direction into the second opening 28 wider than the length in the insertion direction. The contact surface between the first fitting protrusion 18 and the contact surface 22b is also wider in the width direction than the insertion direction of the second opening 28. That is, the first and second openings 17 and 28 have a resistance to impact above the surface 2a of the base member 2 by fitting the first and second fitting protrusions 18 and 29 widely in the width direction. It has a high structure.

Further, since the first and second fitting projections 18 and 29 are not engaged by being press-fitted into the first and second openings 17 and 28, there is no need to provide flexibility. The fitting strength is increased by using a stronger material or making the dimension thicker, and the first and second openings 17 and 28 can be inserted and fitted deeply.

Therefore, when the fuse element 5 is self-heated and interrupted with arc discharge, the first and second fitting protrusions 18 and 29 are softened by the high heat, and the first and second openings are formed. Even if the cover member 3 is suddenly pressurized above the surface 2 a of the base member 2, the first opening 17 and the second fitting convex portion are not released. The fitting with 29 and the fitting between the second opening 28 and the first fitting projection 18 are not released.

The first and second fitting protrusions 18 and 29 have chamfered tapered portions on the tip surfaces that serve as insertion ends into the first and second openings 17 and 28.

Here, the first opening 17 is provided on an extension line of the groove 12 of the base member 2 and has a rectangular shape in which the width direction of the base member 2 is the length direction. Similarly, the 2nd opening part 28 is provided on the extension line of the groove part 12 of the base member 2, and makes the rectangular shape which makes the width direction of the base member 2 a length direction. In other words, the first and second openings 17 and 28 are located on an extension line of the low heat conduction portion 15 that becomes a fusing portion of the fuse element 5. Therefore, the fuse element 1 causes the first and second fitting projections 18 and 29 to correspond to the first and second fitting projections 18 and 29 corresponding to the fusing portion that is susceptible to an impact when arc discharge occurs when the self-heating of the fuse element 5 is interrupted. The second openings 17 and 28 are fitted. Therefore, it is possible to improve the resistance to the thermal influence and the rapidly increasing internal pressure more effectively.

The base member 2 has third and fourth locking pieces 30a projecting on both sides of the first fitting portion 29 of the cover member 3 on both sides of the first opening 17 of the first side wall. A locking step portion 17a for locking 30b is formed. The locking step portion 17 a is used to prevent the cover member 3 from coming off in the in-plane direction of the surface 2 a of the base member 2, and is formed on the side surface of the fitting recess 11 a formed on the outer surface of the first side wall 11. The step shape is formed by projecting in the in-plane direction of the first side wall 11.

The third and fourth locking pieces 30a, 30b project in the surface direction of the surface 2a of the base member 2, and are formed with locking claws 31 that are locked to the locking step 17a at the tip. The locking claw 31 bulges in a plane direction parallel to the surface 2 a of the base member 2 and in a direction orthogonal to the insertion direction of the second fitting convex portion 29 into the first opening 17. The locking claw 31 has a locking surface 31 a that locks to the locking step portion 17 a and an arcuate or tapered sliding surface 31 b that slides on both side surfaces of the first opening 17.

When the third and fourth locking pieces 30a and 30b are inserted into the first opening 17, the sliding surface 31b slides on both side surfaces of the first opening 17 and is bent inward. While being press-fitted, the locking claw 31 passes through the first opening 17, whereby the locking surface 31a is locked to the locking step 17a. Thereby, the cover member 3 is prevented from coming off in the insertion direction of the base member 2.

As described above, the element housing 4 of the fuse element 1 is inserted into the first opening 17 formed on the first side wall 11 of the base member 2 with the second fitting convex portion 29 formed on the cover member 3. As a result, the resistance against pressure above the surface 2 a of the base member 2 is improved, and the third and fourth locking pieces 30 a and 30 b formed on the cover member 3 are formed on the first side wall 11 of the base member 2. By being press-fitted into the formed first opening 17 and the locking claw 31 being locked to the locking step 17a, the surface 2a of the base member 2 that is the insertion direction is prevented from coming off in the surface direction. It has been.

Similarly, the cover member 3 includes first and second locking pieces 19a and 19b projecting from both sides of the first fitting convex portion 18 on both sides of the second opening 28 of the second side wall. A locking step portion 28a is formed to be locked. The locking step portion 28 a is formed on the side surface of the fitting recess 22 a formed on the outer surface of the second side wall 22, and forms a step shape by projecting in the in-plane direction of the second side wall 2. Further, the first and second locking pieces 19a and 19b protrude in the surface direction of the surface 2a of the base member 2, and a locking claw 20 that locks the locking stepped portion 28a is formed at the tip. Yes. The locking claw 20 bulges in a plane direction parallel to the surface 2 a of the base member 2 and in a direction perpendicular to the insertion direction of the first fitting convex portion 18 into the second opening 28. The locking claw 20 has a locking surface 20a that locks to the locking step portion 28a, and an arcuate or tapered sliding surface 20b that slides on both side surfaces of the second opening 28. The configuration and function of the locking step 28a and the first and second locking pieces 19a and 19b are the same as those of the locking step 17a and the third and fourth locking pieces 30a and 30b described above. Details are omitted.

The fuse element 1 is provided with an opening and a locking step on at least one of the base member 2 and the cover member 3 and a locking piece on the other, whereby the surface 2a of the base member 2 in the insertion direction. Can be prevented from coming off in the direction, but preferably, by providing the base member 2 and the cover member 3 with an opening and a locking step, and by locking each other with a locking piece, It is possible to more reliably prevent the cover member 3 from coming off from the base member 2 in the insertion direction.

The fuse element 1 has improved resistance to pressure above the surface 2a of the base member 2 by the first and second locking pieces 19a and 19b coming into contact with the upper surface of the second opening 28. Similarly, the third and fourth locking pieces 30a and 30b are in contact with the upper surface of the first opening 17, so that the resistance to the pressure above the surface 2a of the base member 2 is improved.

[Fuse element]
Next, the fuse element 5 will be described. The fuse element 5 is a low melting point metal such as solder or Pb-free solder whose main component is Sn, or a laminated body of a low melting point metal and a high melting point metal. For example, as shown in FIG. 13, the fuse element 5 is a laminated structure composed of an inner layer and an outer layer, and includes a low melting point metal layer 9 as an inner layer and a refractory metal layer 10 as an outer layer laminated on the low melting point metal layer 9. Have.

The low melting point metal layer 9 is preferably a metal mainly composed of Sn, and is a material generally called “Pb-free solder”. The melting point of the low melting point metal layer 9 is not necessarily higher than the reflow temperature, and may be melted at about 200 ° C. The high melting point metal layer 10 is a metal layer laminated on the surface of the low melting point metal layer 9, and is made of, for example, Ag or Cu or a metal having one of them as a main component. Therefore, it has a high melting point that does not melt even when mounted on an external circuit board.

Even if the reflow temperature exceeds the melting temperature of the low melting point metal layer 9 by laminating the high melting point metal layer 10 as the outer layer on the low melting point metal layer 9 as the inner layer, the fuse element 5 5 does not lead to fusing. Therefore, the fuse element 1 can be efficiently mounted by reflow.

Also, the fuse element 5 is not melted by self-heating while a predetermined rated current flows. When a current having a value higher than the rating flows, melting starts from the melting point of the low melting point metal layer 9 by self-heating, and the current path between the terminal portions 5a and 5b can be quickly cut off. For example, when the low melting point metal layer 9 is made of Sn—Bi alloy or In—Sn alloy, the fuse element 5 starts to melt from a low temperature of about 140 ° C. or about 120 ° C. At this time, the fuse element 5 uses, for example, an alloy containing 40% or more of Sn as a low melting point metal, and the molten low melting point metal layer 9 corrodes the high melting point metal layer 10, thereby causing the high melting point metal layer to melt. 10 melts at a temperature lower than the melting temperature. Therefore, the fuse element 5 can be blown in a short time by utilizing the erosion action of the high melting point metal layer 10 by the low melting point metal layer 9.

In addition, since the fuse element 5 is configured by laminating the high melting point metal layer 10 on the low melting point metal layer 9 as the inner layer, the fusing temperature is significantly reduced as compared with a chip fuse made of a conventional high melting point metal. be able to. Therefore, the fuse element 5 is formed wider than the refractory metal element, and the energization direction is shortened to reduce the size while greatly improving the current rating, and to the connection portion with the circuit board. The influence of heat can be suppressed. In addition, it can be made smaller and thinner than conventional chip fuses having the same current rating, and is excellent in quick fusing.

Also, the fuse element 5 can improve resistance to a surge (pulse resistance) in which an abnormally high voltage is instantaneously applied to the electrical system in which the fuse element 1 is incorporated. That is, the fuse element 5 must not be blown until, for example, a current of 100 A flows for several milliseconds. In this respect, since a large current flowing in a very short time flows in the surface layer of the conductor (skin effect), the fuse element 5 is provided with a refractory metal layer 10 such as Ag plating having a low resistance value as an outer layer. It is easy to flow the current applied by the surge, and it is possible to prevent fusing due to self-heating. Therefore, the fuse element 5 can greatly improve the resistance to a surge as compared with a fuse made of a conventional solder alloy.

The fuse element 5 can be manufactured by forming a high melting point metal layer 10 on the surface of the low melting point metal layer 9 using a film forming technique such as electrolytic plating. For example, the fuse element 5 can be efficiently manufactured by performing Ag plating on the surface of solder foil or thread solder.

The fuse element 5 is preferably formed such that the volume of the low melting point metal layer 9 is larger than the volume of the high melting point metal layer 10. The fuse element 5 melts the high melting point metal when the low melting point metal is melted by self-heating, and can thereby be melted and blown quickly. Therefore, the fuse element 5 forms the volume of the low melting point metal layer 9 larger than the volume of the high melting point metal layer 10, thereby promoting this corrosion action and promptly blocking between the terminal portions 5a and 5b. Can do.

[Deformation restriction section]
As shown in FIG. 4A, the fuse element 5 may be provided with a deformation restricting portion 6 that suppresses the flow of the molten low melting point metal and restricts deformation. Thus, even in the fuse element 5 having a high rating and low resistance by increasing the area, deformation due to the flow of the low melting point metal during reflow heating or the like can be suppressed, and fluctuations in the fusing characteristics can be prevented.

The deformation restricting portion 6 is provided on the surface of the fuse element 5, and as shown in FIG. 13, at least a part of the side surface 7 a of one or a plurality of holes 7 provided in the low melting point metal layer 9 is formed on the high melting point metal layer. 10 is covered with a second refractory metal layer 8 that is continuous with 10. The hole 7 can be formed, for example, by piercing a low-melting-point metal layer 9 with a sharpened body such as a needle, or by pressing the low-melting-point metal layer 9 using a die. Moreover, the shape of the hole 7 can employ | adopt arbitrary shapes, such as an ellipse, a rectangle, etc., for example. Moreover, the hole 7 may be formed in the center part used as the fusing part of the fuse element 5, and may be formed uniformly over the whole surface. In addition, by forming the hole 7 at a position corresponding to the fusing part, it is possible to reduce the amount of molten metal in the fusing part, increase the resistance, and more quickly overheat fusing.

The material constituting the second refractory metal layer 8 has a high melting point that does not melt depending on the reflow temperature, like the material constituting the refractory metal layer 10. The second refractory metal layer 8 is preferably made of the same material as the refractory metal layer 10 and formed together in the process of forming the refractory metal layer 10 in terms of manufacturing efficiency.

[First and second electrodes, first and second external connection electrodes]
The fuse element 5 may be connected to the first and second electrodes formed on the surface 2a of the base member 2 via a connecting material such as solder without providing the terminal portions 5a and 5b. In this case, first and second external connection electrodes that are electrically connected to the first and second electrodes are formed on the back surface and / or the side surface of the base member 2.

[leg]
Further, the cover member 3 has leg portions 35 formed at both ends of the third and fourth side walls 23 and 24. In the fuse element 1, the terminal portions 5a and 5b of the fuse element 5 are provided between the leg portions 35 formed at both ends of the side walls 23 and 24, respectively, and the fuse element 1 is surface-mounted on the terminal portions 5a and 5b. The connecting electrode of the external circuit board is connected with a connecting material for mounting such as solder. As a result, the fuse element 1 is connected to the terminal portion 5a of the fuse element 5 that is connected and fixed with the connecting material for mounting even when the cover member 3 is pulled out in the direction opposite to the direction inserted into the base member 2. The movement of the leg part 35 is inhibited by 5b, and the cover member 3 is prevented from coming off.

Instead of forming the terminal portions 5a and 5b in the fuse element 5, the first and second electrodes are provided on the surface of the base member 2, and the first and second electrodes are connected to the back surface and / or the side surface. When the formed first and second external connection electrodes are formed, the cover member 3 is arranged on a side different from the side where the second fitting convex portion 29 and / or the second side wall 22 are provided. 1. The mounting connection connected to the first and second external connection electrodes and / or the first and second external connection electrodes when the second external connection electrodes are exposed and mounted on the external circuit board. The movement of the leg part 35 is inhibited by the material (fillet). Therefore, the cover member 3 can be prevented from coming off even when a force is applied to the cover member 3 so that the cover member 3 is pulled out in the direction opposite to the direction inserted into the base member 2.

Such a fuse element 1 has a circuit configuration shown in FIG. The fuse element 1 is mounted on an external circuit via the terminal portions 5a and 5b, thereby being incorporated on the current path of the external circuit. The fuse element 1 is not melted by self-heating while a predetermined rated current flows through the fuse element 5. When the overcurrent exceeding the rating is energized, the fuse element 1 causes the low heat conduction portion 15 to melt due to self-heating of the fuse element 5 and cuts off the current path of the external circuit by cutting off between the terminal portions 5a and 5b. (FIG. 14B).

At this time, as described above, in the fuse element 5, the heat generated by the heat generation portion 14 is actively radiated through the base member 2 and the cover member 3, and the low heat conduction formed along the grooves 12 and 26. The part 15 can be selectively heated. Therefore, the fuse element 5 can melt the low heat conducting portion 15 while suppressing the influence of heat on the terminal portions 5a and 5b and the mounting adhesive material.

In addition, as described above, the fuse element 1 causes the fuse element 5 to arc due to overcurrent by fitting the second fitting convex portion 28 of the cover member 3 into the first opening 17 of the base member 2. Even when pressure is suddenly applied to the cover member 3 above the surface 2a of the base member 2 when self-heating is interrupted with discharge, the second fitting is performed at the contact surface 11b continuous with the first opening 17. By holding down the convex portion 29, the resistance to the pressure above the surface 2 a of the base member 2 is improved, and the cover member 3 can be prevented from coming off the base member 2.

Further, by including the low melting point metal layer 9 having a melting point lower than that of the high melting point metal layer 10, the melting starts from the melting point of the low melting point metal layer 9 due to self-heating due to overcurrent, and the high melting point metal layer 10 is eroded. Begin to. Therefore, the fuse element 5 uses the erosion action of the refractory metal layer 10 by the low-melting-point metal layer 9 so that the refractory metal layer 10 is melted at a temperature lower than its melting point and can be quickly blown out. it can.

[Material of base member and cover member]
Here, in the fuse element 1, the base member and the cover member are preferably formed of a plastic material having a tracking resistance of 250 V or more. This is due to the following circumstances.

That is, in recent years, halogen-free electronic components have been developed in accordance with environmental requirements, and the element housing material of the fuse element has been replaced with a halogen-free LCP. Applications of this type of fuse element have expanded from electronic devices to industrial machines, electric bicycles, electric bikes, automobiles and other high-current applications. For this reason, with the increase in capacity and rating of mounted electronic devices and battery packs, the fuse element is required to further improve the current rating.

In order to increase the current rating, it is effective to reduce the resistance by increasing the size of the fuse element. However, the fuse element is blown when an overcurrent exceeding the rating flows, and arc discharge is generated along with the blow. Therefore, when the fuse element is increased in size, the heat generated by arc discharge increases in proportion to the increase in size.

Also, as the current rating is improved, the amount of heat generated at the time of self-heat cutoff due to overcurrent increases and the thermal effect on the element housing also increases. For example, when the current rating of the fuse element rises to the 100 A level and the rated voltage rises to the 60 V level, the surface facing the fuse element of the element casing is carbonized by arc discharge at the time of current interruption, and leakage current flows to insulate. There is also a concern that the resistance may decrease, the element housing may be damaged due to fire, or may be displaced from the mounting substrate or dropped. This is because the aromatic ring in the main chain of the liquid crystal polymer is carbonized by arc discharge.

Current countermeasures to quickly stop arc discharge and shut off the circuit include a hollow case filled with an arc extinguishing material, or a high voltage compatible current that generates a time lag by spirally wrapping a fuse element around the heat dissipation material Fuses have also been proposed. However, conventional high-voltage current fuses require complicated materials and processing processes, such as arc-quenching material encapsulation and spiral fuse manufacturing, and the fuse element is downsized and current rating is increased. It is disadvantageous in terms.

Furthermore, the element housing material is made of a non-burning inorganic material such as a ceramic material, so that the insulation resistance can be reduced and the ignition can be suppressed. However, there is a demerit that the material cost and the process cost are increased.

Therefore, there is a need for a fuse element that can handle high-rated and large-current applications, has excellent arc resistance when interrupting current, improves insulation resistance, and prevents the element housing from falling off the mounting board. It has been.

In the fuse element to which the present technology is applied, the base member 2 and the cover member 3 constituting the element housing are formed of a plastic material having a tracking resistance of 250 V or more, so that an arc discharge is generated when the fuse element is blown. In this case, the insulation resistance is prevented from lowering due to leakage due to carbonization of the base member and cover member, and the ignition due to the tracking phenomenon is prevented. Can also be prevented.

The plastic material constituting the base member 2 and the cover member 3 is preferably a nylon material. By using a nylon plastic material, the tracking resistance of the base member 2 and the cover member 3 can be 250V or more. The tracking resistance can be obtained by a test based on IEC60112.

Among the nylon plastic materials constituting the base member 2 and the cover member 3, it is particularly preferable to use nylon 46. Thereby, the fuse element 1 can improve tracking resistance to 600V or more.

As described above, in the fuse element 1, the second fitting convex portion 29 formed in the cover member 3 is fitted into the first opening 17 formed in the first side wall 11 of the base member 2. Further, the first fitting protrusion 18 formed on the base member 2 is fitted into the second opening 28 formed on the second side wall 22 of the cover member 3.

Thereby, in the fuse element 1, the contact surface 11b of the fitting recess 11a contacts the upper surface of the second fitting projection 29 (FIG. 1), and the contact surface 22b of the fitting recess 22a is the first. It contacts the lower surface of the fitting projection 18 (FIG. 3). Therefore, the fuse element 1 has the first opening even when pressure is suddenly applied to the cover member 3 above the surface 2a of the base member 2 when the fuse element 5 is cut off by self-heating due to arc discharge due to overcurrent. The second fitting convex portion 29 is pressed by the contact surface 11 b continuous with the portion 17, and the contact surface 22 b continuous with the second opening portion 28 is pressed by the first fitting convex portion 18. The resistance to the pressure above the surface 2a of the base member 2 is improved.

At this time, the fuse element 1 uses a plastic material having a tracking resistance of 250 V or more, preferably a polyamide resin, more preferably an aliphatic polyamide resin for the base member 2 and the cover member 3 constituting the element housing. It is formed. This prevents a decrease in insulation resistance due to the occurrence of leakage due to carbonization of the base member 2 and the cover member 3 even when a fuse element used for a large current application is accompanied by arc discharge at the time of interruption and generates high heat. In addition, ignition due to the tracking phenomenon can be prevented.

Examples of the aliphatic polyamide resin include polyamide 46 (melting point: 290 ° C., glass transition temperature: 78 ° C.), polyamide 66 (melting point: 262 ° C., glass transition temperature: 66 ° C.), polyamide 6 (melting point: 222 ° C., glass Transition temperature: 59 ° C.). Among these, polyamide 46 having a high melting point and glass transition temperature is particularly preferable. Thereby, even when arc discharge occurs at the time of fusing of the fuse element corresponding to a large current and the inside of the element housing 4 becomes high temperature, it has excellent resistance to deformation due to thermal influence. The fitting strength between the opening 17 and the second fitting convex portion 29 of the cover member 3 is maintained, and the second opening 28 of the cover member 3 and the first fitting convex portion 18 of the base member 2 are maintained. The fitting strength with can be maintained.

Table 1 shows the main characteristics comparison between HF nylon and LCP.

As shown in Table 1, it can be seen that the aliphatic polyamide resin, especially polyamide 46, has the same performance in terms of flammability and melting point as LCP, and has extremely excellent tracking resistance.

The fuse element 1 includes first to fourth locking pieces 19a, 19b, 30a, 30b that are locked to the locking step portions 17a, 28a of the first and second openings 17, 28, respectively. By being formed of a plastic material having high tracking resistance such as polyamide 46, it is prevented from falling off from the locking step portions 17a and 28a due to softening even in a high temperature environment due to arc discharge, and the surface 2a of the base member 2 The resistance to pressure in the surface direction is also improved. Therefore, the fuse element 1 can maintain the fitting between the base member 2 and the cover member 3.

[Example]
A tracking resistance test based on a difference in plastic material constituting the element housing 4 will be described. The above-described fuse element 1 was manufactured using LCP and HF nylon PA46, and an overcurrent test was performed. The fuse element mounted on each fuse element sample is a 200 μm thick Sn—Ag—Cu solder foil (Sn: Ag: Cu = 96.5% by mass: 3.0% by mass) which becomes a low melting point metal constituting the inner layer. : 0.5% by mass), Ag plating was applied by electrolytic plating, and a refractory metal layer was laminated. Further, eight LCP and HF nylon fuse element samples were prepared, 200 A and 36 V currents were applied, the fuse element was blown, and the insulation resistance after blowing was measured.

As shown in Table 2, the LCP fuse element had a minimum insulation resistance of less than 1.0E + 6Ω, whereas the HF nylon fuse element had a minimum insulation resistance of 1.1E + 11Ω. That is, it can be understood that the fuse element made of HF nylon has a low tendency to burn and can maintain insulation even when arc discharge occurs due to fusing of the fuse element. In addition, since there was a sample in which the insulation resistance was not measurable with LCP (Range 最低 Over), the minimum insulation resistance was set to less than 1.0E + 6Ω.

[Heating element]
The present technology can also be applied to a fuse element 40 in which a heating element 41 is provided on the base member 2 as shown in FIGS. In the following description, the same members as those of the fuse element 1 described above are denoted by the same reference numerals, and the details thereof are omitted. The fuse element 40 to which the present invention is applied includes a base member 2, a heating element 41 laminated on the base member 2 and covered with an insulating member 42, first electrodes 43 formed on both ends of the base member 2, and A second electrode 44, a heating element extraction electrode 45 laminated on the base member 2 so as to overlap the heating element 41, and electrically connected to the heating element 41, and both ends of the first and second electrodes 43. , 44, and a fuse element 5 having a central portion connected to a heating element extraction electrode 45. In the fuse element 40, the base member 2 and the cover member 3 constitute an element housing 4 by bonding or fitting to each other.

First and second electrodes 43 and 44 are formed on the surface 2a of the base member 2 at opposite ends. When the heating element 41 is energized to generate heat when the first and second electrodes 43 and 44 are heated, the fused fuse element 5 gathers due to its wettability, and the terminal portions 5a and 5b are fused.

The heating element 41 is a conductive member that generates heat when energized, and is made of, for example, nichrome, W, Mo, Ru, or a material containing these. The heating element 41 is obtained by forming a paste by mixing a powdery body of these alloys, compositions, or compounds with a resin binder or the like, and forming a pattern on the base member 2 using a screen printing technique, followed by firing. Etc. can be formed.

In the fuse element 40, the heating element 41 is covered with an insulating member 42, and a heating element extraction electrode 45 is formed so as to face the heating element 41 with the insulating member 42 interposed therebetween. The heating element lead-out electrode 45 is connected to the fuse element 5, whereby the heating element 41 is superimposed on the fuse element 5 via the insulating member 42 and the heating element lead-out electrode 45. The insulating member 42 is provided to protect and insulate the heating element 41 and to efficiently transmit the heat of the heating element 41 to the fuse element 5 and is made of, for example, a glass layer.

The heating element 41 may be formed inside the insulating member 42 stacked on the base member 2. The heating element 41 may be formed on the back surface 2b opposite to the front surface 2a of the base member 2 on which the first and second electrodes 43 and 44 are formed, or the heating element 41 may be formed on the front surface 2a of the base member 2. It may be formed adjacent to the first and second electrodes 43 and 44. Further, the heating element 41 may be formed inside the base member 2.

In addition, the heating element 41 is connected to the heating element extraction electrode 45 through a first heating element electrode 48 formed at one end on the surface 2 a of the base member 2, and the other end on the surface 2 a of the base member 2. It is connected to the formed second heating element electrode 49. The heating element extraction electrode 45 is connected to the first heating element electrode 48, is laminated on the base member 2 so as to face the heating element 41, and is connected to the fuse element 5. Thereby, the heating element 41 is electrically connected to the fuse element 5 via the heating element extraction electrode 45. The heating element extraction electrode 45 is disposed opposite to the heating element 41 with the insulating member 42 interposed therebetween, whereby the fuse element 5 can be melted and the molten conductor can be easily aggregated.

Further, the second heating element electrode 49 is formed on the front surface 2a of the base member 2, and the heating element feeding electrode 49a formed on the back surface 2b of the base member 2 through castellation (see FIG. 16A). And is continuous.

The fuse element 40 is connected to the fuse element 5 across the second electrode 44 from the first electrode 43 through the heating element extraction electrode 45. The fuse element 5 is connected to the first and second electrodes 43 and 44 and the heating element extraction electrode 45 through a connection material such as a connection solder.

[flux]
Further, the fuse element 40 is provided with a surface of the fuse element 5 for preventing oxidation and sulfidation of the high melting point metal layer 10 or the low melting point metal layer 9, removing oxides and sulfides at the time of fusing, and improving solder fluidity. A flux 47 may be coated on the back surface. Coating the flux 47 increases the wettability of the low melting point metal layer 9 (for example, solder) and removes oxides and sulfides while the low melting point metal is dissolved when the fuse element 40 is actually used. In addition, the fusing characteristics can be improved by using an erosion action on a refractory metal (for example, Ag).

Even when an anti-oxidation film such as Pb-free solder containing Sn as a main component is formed on the surface of the outermost refractory metal layer 10 by coating the flux 47, the oxide of the anti-oxidation film It is possible to effectively prevent oxidation and sulfidation of the refractory metal layer 10, and maintain and improve the fusing characteristics.

The first and second electrodes 43 and 44, the heating element extraction electrode 45, and the first and second heating element electrodes 48 and 49 are formed by a conductive pattern such as Ag or Cu, and Sn is appropriately formed on the surface. A protective layer such as plating, Ni / Au plating, Ni / Pd plating, or Ni / Pd / Au plating is preferably formed. Thereby, oxidation and sulfurization of the surface can be prevented, and erosion of the first and second electrodes 43 and 44 and the heating element extraction electrode 45 due to the connection material such as solder for connecting the fuse element 5 can be suppressed.

In addition, the fuse element 40 constitutes a part of the energization path to the heating element 41 by connecting the fuse element 5 to the heating element extraction electrode 45. Therefore, when the fuse element 5 is melted and the connection with the external circuit is cut off, the fuse element 40 can also stop the heat generation because the energization path to the heating element 41 is also cut off.

[circuit diagram]
The fuse element 40 to which the present invention is applied has a circuit configuration as shown in FIG. That is, the fuse element 40 is heated by energizing the fuse element 5 connected in series across the pair of terminal portions 5a and 5b via the heating element lead electrode 45 and the connection point of the fuse element 5 to generate heat. 5 is a circuit configuration including a heating element 41 that melts 5. The fuse element 40 has terminal portions 5a and 5b provided at both ends of the fuse element 5 and heating element feeding electrodes 49a connected to the second heating element electrodes 49 are connected to the external circuit board. As a result, the fuse element 40 has the fuse element 5 connected in series on the current path of the external circuit via the terminal portions 5a and 5b, and the heating element 41 provided in the external circuit via the heating element feeding electrode 49a. Connected to the control element.

[Fusing process]
In the fuse element 40 having such a circuit configuration, when the current path of the external circuit needs to be interrupted, the heating element 41 is energized by the current control element provided in the external circuit. As a result, the fuse element 40 is melted by the heat generated by the heat generating element 41, and the fuse element 5 incorporated on the current path of the external circuit is melted. The fuse element 5 is blown by being attracted to the first and second electrodes 43 and 44. As a result, the fuse element 5 is reliably fused between the terminal portion 5a and the heating element extraction electrode 45 and the terminal portion 5b (FIG. 16B), and the current path of the external circuit can be interrupted. Further, when the fuse element 5 is melted, power supply to the heating element 41 is also stopped.

At this time, the fuse element 5 starts melting from the melting point of the low melting point metal layer 9 having a melting point lower than that of the high melting point metal layer 10 due to the heat generation of the heating element 41 and starts to erode the refractory metal layer 10. Therefore, the fuse element 5 uses the erosion action of the refractory metal layer 10 by the low melting point metal layer 9, so that the refractory metal layer 10 is melted at a temperature lower than the melting temperature, and the current path of the external circuit is quickly obtained. Can be cut off.

In addition, by using a plastic material having excellent tracking resistance for the base member 2 and the cover member 3, when the fuse element 5 is melted and cut off, the insulation resistance is reduced due to leakage due to carbonization of the base member 2 and the cover member 3. In addition, it is possible to prevent ignition due to a tracking phenomenon.

The fuse elements 1 and 40 described above were surface-mounted on the external circuit board by connecting the terminal portions 5a and 5b of the fuse element 5 to external connection terminals provided on the external circuit board by soldering or the like. The fuse elements 1 and 40 to which the present technology is applied can be used for connections other than surface mounting.

For example, in the fuse elements 1 and 40 to which the present technology is applied, the terminal portions 5a and 5b of the fuse element 5 may be connected to a metal plate serving as an external connection terminal capable of handling a large current. The connection between the terminal portions 5a and 5b of the fuse element 5 and the metal plate may be connected by a connecting material such as solder, or the terminal portions 5a and 5b may be sandwiched between clamp terminals connected to the metal plate, Or you may carry out by screwing terminal part 5a, 5b or a clamp terminal to the metal plate with the screw which has electroconductivity.

[Modification of fuse element]
Next, modified examples of the fuse element according to the present invention will be described. In the following description, the same members as those of the fuse elements 1 and 40 described above are denoted by the same reference numerals and their details are omitted.

The fuse element 50 to which the present invention is applied has a base member 2 and a cover member 3 covering the surface 2a of the base member 2 as shown in FIG. The base member 2 and the cover member 3 constitute an element housing 4 by fitting with each other. 17A is a plan view showing the fuse element 50 from the cover member 3 side, FIG. 17B is a side view of the fuse element 50, and FIG. 17C is a rear view of the fuse element 50. FIG. 17D is a front view of the fuse element 50, and FIG. 17E is a rear view showing the fuse element 50 from the base member 2 side.

[Base member]
As shown in FIG. 18 to FIG. 22, the base member 2 has the fuse element 5 mounted on the surface 2a and intersects with the surface direction of the surface 2a on one side edge side. The 1st side wall 11 which comprises is erected. The first side wall 11 has a fitting recess 11a formed therein, and a first opening 17 into which a second fitting projection 29 formed on the cover member 3 described later is fitted in the fitting recess 11a, and An abutting surface 11 b that is continuous with the first opening 17 and abuts on the second fitting convex portion 29 inserted into the first opening 17 is formed.

18 is an external perspective view showing the base member 2 from the first side wall 11 side, FIG. 19 is an external perspective view showing the base member 2 from the first fitting convex portion 18 side, and FIG. FIG. 21 is an external perspective view showing the back surface of the base member 2 from the first side wall 11 side, and FIG. 21 is an external perspective view showing the back surface of the base member 2 from the first fitting convex portion 18 side. 22A is a plan view of the base member 2, FIG. 22B is a side view of the base member 2, FIG. 22C is a rear view of the base member 2, and FIG. D) is a front view of the base member 2, and FIG. 22 (E) is a rear view of the base member 2.

The base member 2 of the fuse element 50 protrudes outward from a surface intersecting the surface 2a of the base member 2 on the other side edge opposite to the one side edge on which the first side wall 11 is provided. A first fitting convex portion 18 that fits into a second opening 28 formed in the second side wall 22 formed in the cover member 3 to be described later is formed. The first fitting projection 18 preferably projects outward along a plane parallel to the surface 2 a of the base member 2.

[Cover member]
As shown in FIGS. 23 to 27, the cover member 3 is provided with a second side wall 22 constituting a side surface facing the first side wall 11 of the element housing 4 and a terminal portion provided in the energizing direction of the fuse element 5. 5a and 5b have third and fourth side walls 23 and 24 that are exposed to the outside, and a top surface portion 25 that constitutes the top surface of the element housing 4.

23 is an external perspective view showing the cover member 3 from the second fitting convex portion 29 side, FIG. 24 is an external perspective view showing the cover member 3 from the second side wall 22 side, and FIG. FIG. 26 is an external perspective view showing the inner surface of the cover member 3 from the second fitting convex portion 29 side, and FIG. 26 is an external perspective view showing the inner surface of the cover member 3 from the second side wall 22 side. 27A is a plan view of the cover member 3, FIG. 27B is a side view of the cover member 3, FIG. 27C is a rear view of the cover member 3, and FIG. D) is a front view of the cover member 3, and FIG. 27E is a back view of the cover member 3.

The second side wall 22 is formed on one side edge side of the cover member 3, and is erected in a direction intersecting, preferably substantially perpendicular to the surface direction of the surface 2 a of the base member 2. Configure. The second side wall 22 is formed with a fitting recess 22a, and in the fitting recess 22a, a second opening 28 in which the first fitting protrusion 18 formed on the base member 2 is fitted, and A contact surface 22b is formed which is continuous with the second opening 28 and contacts the first fitting convex portion 18 inserted into the second opening 28.

The cover member 3 of the fuse element 50 is formed on the other side edge opposite to the one side edge provided with the second side wall 22 from the surface intersecting the surface direction of the surface 2a of the base member 2 to the outside. A second fitting convex portion 29 is formed so as to protrude and fit into the first opening 17 formed in the first side wall 11 of the base member 2 described above. The second fitting convex portion 29 preferably projects outward along a plane parallel to the surface 2 a of the base member 2.

In the fuse element 50, the second fitting protrusion 29 formed in the cover member 3 is fitted into the first opening 17 formed in the first side wall 11 of the base member 2, and the cover member The first fitting protrusion 18 formed in the base member 2 is fitted into the second opening 28 formed in the third second side wall 22.

At this time, the fuse element 50 is fitted into the fitting concave portion by fitting the second fitting convex portion 29 of the cover member 3 into the first opening 17 of the base member 2 in the same manner as the fuse element 1 described above. The contact surface 11b of 11a contacts the upper surface of the second fitting convex portion 29. Further, when the first fitting convex portion 18 of the base member 2 is fitted into the second opening 28 of the cover member 3, the contact surface 22 b of the fitting concave portion 22 a becomes the first fitting convex portion 18. It contacts the lower surface of the.

As a result, when the fuse element 5 is cut off by self-heat generation with arc discharge due to overcurrent, even if a sudden pressure is applied to the cover member 3 above the surface 2 a of the base member 2, it continues to the first opening 17. The second fitting convex portion 29 is pressed by the abutting contact surface 11b, and the contact surface 22b continuous with the second opening 28 is pressed by the first fitting convex portion 18, whereby the base member 2 is pressed. The resistance to the pressure above the surface 2a of the cover member 3 is improved, and the cover member 3 can be prevented from being detached from the base member 2.

As shown in FIG. 28, the fuse element 50 intersects at least the surface direction of the surface 2 a of the base member 2 of the base member 2 and the cover member 3, and is on one of the side edges constituting the side surface of the element housing 4. By providing the opening and the fitting protrusion on the other side, it is possible to improve the resistance to the pressure above the surface 2a of the base member 2, but preferably each of the base member 2 and the cover member 3 It is possible to prevent the cover member 3 from being detached from the base member 2 more reliably by providing the opening and the fitting convex portion so as to be fitted to each other.

[Fitting claw / convex surface]
In the fuse element 50, the first fitting convex portion 18 of the base member 2 bulges in a direction intersecting with the insertion direction into the second opening 28 formed in the second side wall 22. A fitting claw 51 is formed. In the fuse element 50, the cover member 3 has a second convex surface portion 57 that bulges in the direction intersecting the insertion direction of the first fitting convex portion 18 on the contact surface 22 b of the second opening 28. Is formed.

Similarly, the second fitting convex portion 29 of the cover member 3 has a second fitting that bulges in a direction intersecting with the insertion direction to the first opening 17 formed in the first side wall 11. A claw portion 56 is formed. In the fuse element 50, the base member 2 has a first convex surface portion 52 that bulges on the contact surface 11 b of the first opening portion 17 in a direction intersecting the insertion direction of the second fitting convex portion 29. Is formed.

As shown in FIG. 28, the first fitting claw portion 51 and the second convex surface portion 57, and the second fitting claw portion 56 and the first convex surface portion 52 are engaged with each other to thereby cover the cover member. 3 is intended to prevent the surface 2a of the base member 2 from coming off in the in-plane direction.

The second fitting claw 56 is formed on the surface facing the contact surface 11b when the second fitting projection 29 is inserted into the first opening 17. The bulge is formed over the width direction. Further, the second fitting claw portion 56 has a second fitting surface that gets over the first convex surface portion 52 and is locked when the second fitting convex portion 29 is inserted into the first opening 17. 56a is formed. Further, the second fitting claw portion 56 is formed with a second taper portion 58 that is in sliding contact with the first convex surface portion 52 when the second fitting convex portion 29 is inserted into the first opening portion 17. Yes. The second taper portion 58 is formed so that the second fitting convex portion 29 becomes thinner toward the tip of the second fitting convex portion 29. Accordingly, when the second fitting convex portion 29 is press-fitted into the first opening portion 17 while being slightly bent, the first convex surface portion 52 slides on the second tapered portion 58, and the second fitting convex portion 29 is bent. The claw portion 56 can smoothly get over the first convex surface portion 52, and the second fitting surface 56 a can be locked to the first convex surface portion 52. Thereby, the cover member 3 is prevented from coming off in the insertion direction of the base member 2.

Thus, the element housing 4 of the fuse element 50 is inserted into the first opening 17 formed in the first side wall 11 of the base member 2 with the second fitting convex portion 29 formed in the cover member 3. Thereby, the tolerance with respect to the pressure which concerns on the upper direction of the surface 2a of the base member 2 is improved. Further, the element housing 4 is press-fitted into the first opening 17 formed in the first side wall 11 of the base member 2 by the second fitting claw 56 formed in the second fitting convex portion 29. At the same time, the second fitting surface 56a is locked to the first convex surface portion 52, thereby preventing the surface 2a of the base member 2 in the insertion direction from coming off in the surface direction. Further, the element housing 4 is formed by bulging the second fitting claw portion 56 from the second fitting convex portion 29 in the direction in which the cover member 3 is separated from the base member 2 in the vertical direction, and the first convex surface. Since the portion 52 is bulged from the contact surface 11b in the opposite direction to the second fitting claw portion 56, when the pressure at the time of breaking the fuse element 5 is applied in the vertical direction, the mutual catching strength is increased. The base member 2 and the cover member 3 can be prevented from coming off more reliably.

Similarly, the first fitting claw 51 is formed on the surface facing the contact surface 22b when the first fitting projection 18 is inserted into the second opening 28. The portion 18 bulges out in the width direction. Further, the first fitting claw portion 51 has a first fitting surface that gets over the second convex surface portion 57 and is locked when the first fitting convex portion 18 is inserted into the second opening 28. 51a is formed. Further, the first fitting claw portion 51 is formed with a first taper portion 53 that is in sliding contact with the second convex surface portion 57 when the first fitting convex portion 18 is inserted into the second opening 28. Yes. The first tapered portion 53 is formed so that the first fitting convex portion 18 becomes thinner toward the tip of the first fitting convex portion 18. Thus, when the first fitting convex portion 18 is press-fitted into the second opening 28 while being slightly bent, the second convex surface portion 57 slides on the first tapered portion 53, and the first fitting convex portion 18 is bent. The claw portion 51 can smoothly get over the second convex surface portion 57, and the first fitting surface 51 a can be locked to the second convex surface portion 57. Since the configurations and functions of the first fitting claw portion 51 and the second convex surface portion 57 are the same as those of the second fitting claw portion 56 and the first convex surface portion 52 described above, details are omitted.

The fuse element 50 is provided with an opening and a convex surface portion on at least one of the base member 2 and the cover member 3 and a fitting claw portion on the other side, whereby the surface direction of the surface 2a of the base member 2 that is the insertion direction. However, it is preferable that the base member 2 and the cover member 3 are provided with an opening and a convex surface portion, and a fitting claw portion is provided and locked together. It is possible to prevent the cover member 3 from being detached from the base member 2.

Note that the fuse element 50 may be configured such that the first and second fitting convex portions 18 and 29 abut on the upper surfaces of the first and second convex surface portions 52 and 57, and this also The tolerance to the pressure above the surface 2a can be improved.

The fuse element 50 includes the first and second taper portions 53 and 58 formed on the first and second fitting claws 51 and 56 that are in sliding contact with the first and second convex surface portions 52 and 57. In addition, a tapered portion may be formed on all side edges of the tip surfaces of the first and second fitting convex portions 18 and 29. Thereby, when the base member 2 and the cover member 3 are assembled, the first and second fitting convex portions 18 and 29 can be smoothly inserted into the first and second opening portions 17 and 28.

[Concave]
In the fuse element 50, a recess 60 that forms an internal space apart from the fuse element 5 may be formed on the inner surface 25 a of the cover member 3 facing the surface 2 a of the base member 2. When the fuse element 5 is melted, the concave portion 60 instantaneously becomes hot, and when the air inside the element housing 4 rapidly expands, the recessed portion 60 releases the expanded air to decompress the inside of the element housing 4. The area where the vaporized substance adheres to the melted fuse element 5 is increased, and the decrease in insulation resistance due to the continuous vaporized substance on the inner surface 25a of the cover member 3 is prevented.

The recess 60 is provided, for example, on the inner surface 25a of the cover member 3 adjacent to the contact portion that is in thermal contact with the fuse element 5 and between the low thermal conduction portion 15 that becomes a fusing part of the fuse element 5. Form. Moreover, it is preferable that the internal space formed by the recess 60 is continuous with the groove portion 26 that becomes a fusing part of the fuse element 5.

By forming the recess 60, the fuse element 50 decompresses the expanded air at the time of fusing of the fuse element 5 at the recess 60 and positively attaches the vaporized material of the fuse element 5 melted at the groove 26 to the recess 60. Therefore, it is possible to prevent a large amount of vaporized substance from adhering to and depositing on the inner surface 25a and the groove portion 26 and lowering the insulation resistance between the terminal portions 5a and 5b of the fuse element 5.

Further, the recess 60 may be formed continuously from the inner surface 25a of the cover member 3 to the inner surfaces of the third and fourth side walls 23 and 24 where the leg portions 35 are formed, and further, the third and fourth side walls. You may make it continue outside from the lower part of 23,24. As a result, the fuse element 50 discharges the expanding gas generated when the fuse element 5 is blown out through the recess 60, and the element casing 4 is damaged or the element casing 4 is mounted due to a sudden rise in internal pressure. It is possible to prevent peeling from the external circuit board.

[Material of base member and cover member]
In the fuse element 50, it is preferable that the base member and the cover member are made of a plastic material having a tracking resistance of 250 V or more, and the base member 2 and the cover member 3 are formed similarly to the fuse element 1 described above. It is particularly preferable to use nylon 46 among nylon plastic materials. Thereby, the fuse element 1 can improve tracking resistance to 600V or more. Since the configuration and function of the material of the base member and the cover member are the same as those of the fuse element 1 described above, the details are omitted.

[Heating element]
The fuse element 50 may be provided with a heating element 41 on the base member 2 in the same manner as the fuse element 40 described above. In the fuse element 50, the configuration and function of providing the heating element are the same as those of the above-described fuse element 40, and thus the details are omitted.

[Hem]
In addition, the fuse elements 1 and 50 may be provided with a skirt portion 61 projecting outward at the lower end edge of both side surfaces with which the fuse element 5 of the base member 2 is fitted. The skirt 61 preferably has a structure that enters the lower part of the bent part or the inclined part of the fuse element 5 connected to the terminal parts 5a and 5b by fitting the fuse element 5 to the surface 2a of the base member 2.

Thereby, in the fuse elements 1 and 50, the terminal portions 5a and 5b of the fuse element 5 and the bent portions and the inclined portions of the fuse element 5 are partially overlapped on the skirt portion 61, and the fuse element 5 of the fuse element 5 due to overcurrent is overlapped. Even when the fusing area of the fuse element 5 extends to the high heat conducting portion 14 at the time of interruption, the skirt portion 61 is caught by the terminal portions 5a and 5b and the bent portion of the fuse element 5 and is mounted via the terminal portions 5a and 5b. Omission from the external circuit board can be suppressed.

1 fuse element 1, 2 base member, 2a surface, 3 cover member, 4 element housing, 5 fuse element, 5a, 5b terminal part, 6 deformation regulating part, 7 hole, 9 low melting point metal layer, 10 high melting point metal layer , 11 1st side wall, 11a fitting recess, 12 groove part, 14 high heat conduction part, 15 low heat conduction part, 16 positioning wall, 17 first opening part, 17a locking step part, 18 first fitting convex part , 19 locking piece, 20 locking claw, 20a locking surface, 20b sliding surface, 22 second side wall, 22a fitting recess, 23 third side wall, 24 fourth side wall, 25 top surface portion, 26 groove portion , 27 positioning wall, 28 second opening, 28a locking step, 29 second fitting convex, 30 locking claw, 31a locking surface, 31b sliding surface, 35 leg, 40 fuse element, 41 Thermal body, 42 insulating member, 43 first electrode, 44 second electrode, 45 heating element extraction electrode, 47 flux, 48 first heating element electrode, 49 second heating element electrode, 50 fuse element, 51st 1 fitting claw portion, 51a first fitting surface, 52 first convex surface portion, 53 first taper portion, 56 second fitting claw portion, 56a second fitting surface, 57 second Convex part, 58 second taper part, 60 concave part, 61 hem part

Claims (44)

1. A base member;
   A cover member fitted with the base member and covering the surface of the base member;
   A fuse element disposed between the base member and the cover member;
   One of the base member and the cover member is provided with a side wall that intersects the surface direction of the surface of the base member and has an opening, and the other of the base member and the cover member is provided on the other side. A fuse element provided with a fitting convex portion that projects outward from a surface intersecting the surface and is fitted into the opening of the side wall.
2. The base member or the cover member on which the fitting convex portion is formed protrudes outside from the surface intersecting the surface of the base member adjacent to the fitting convex portion, and the opening at the tip. 2. The fuse according to claim 1, wherein a locking claw that bulges in a direction intersecting with the insertion direction is formed, and one or a plurality of locking pieces that lock the locking claw with the opening are formed. element.
3. The base member and the cover member are each provided with a side wall in which the opening is formed on one of opposing sides, and the fitting protrusion on the other of the opposing sides. Or the fuse element of 2.
4. The side wall is provided with a contact surface that is continuous with the opening and is in contact with the fitting protrusion.
   The fitting protrusion is formed such that the length in the width direction intersecting the insertion direction into the opening is wider than the length in the insertion direction,
   3. The fuse element according to claim 1, wherein a contact surface between the fitting convex portion and the contact surface is wider in the width direction than the insertion direction of the opening.
5. The fuse element according to claim 1 or 2, wherein the fitting convex portion is fitted to the opening from the tip to the base.
6. 3. The fuse element according to claim 1, wherein the side wall is erected with respect to the surface direction of the surface of the base member.
7. The fuse element according to claim 1 or 2, wherein the fitting convex portion projects outward along a plane parallel to the surface of the base member.
8. 3. The fuse element according to claim 2, wherein the locking claw swells in a plane direction parallel to the surface of the base member and in a direction perpendicular to the insertion direction of the fitting convex portion into the opening.
9. The fuse element has terminal portions connected to electrodes formed on the external circuit board at both ends,
   In the cover member, the terminal part of the fuse element is exposed on a side different from the side on which the fitting convex part and / or the side wall is provided, and the insertion direction of the terminal part or the direction opposite to the insertion direction The fuse element according to claim 1 or 2 in which a leg part which controls movement of is formed.
10. The base member is provided with first and second electrodes on which the fuse element is mounted on the front surface, and first and second electrodes connected to the first and second electrodes on the back surface and / or side surfaces. An external connection electrode is provided,
    When the first and second external connection electrodes are exposed on a side different from the side where the fitting convex part and / or the side wall are provided, and the cover member is mounted on the external circuit board, The second external connection electrode and / or the mounting connection material connected to the first and second external connection electrodes are formed with leg portions that restrict movement in the insertion direction or in the direction opposite to the insertion direction. The fuse element according to claim 1 or 2.
11. The fuse element according to claim 1 or 2, wherein a groove portion is provided in a part of a surface of the base member and / or the cover member facing the fuse element.
12. 12. The fuse element according to claim 11, wherein the groove portion of the base member and / or the cover member is formed in a direction crossing the energization direction of the fuse element.
13. The fuse element according to claim 1 or 2, wherein the base member and the cover member are made of a plastic material having a tracking resistance of 250 V or more.
14. The fuse element according to claim 13, wherein the plastic material is a nylon material.
15. The fuse element according to claim 14, wherein the plastic material has a tracking resistance of 600V or more.
16. The fuse element according to claim 1 or 2, wherein the fuse element is a surface mount type.
17. 3. The fuse element according to claim 1, wherein the fuse element is a high melting point solder mainly composed of lead.
18. The fuse element according to claim 1, wherein the fuse element is a laminated body including a high melting point metal layer and a low melting point metal layer.
19. The fuse element according to claim 18, wherein the fuse element has a covering structure of a low melting point metal layer as an inner layer and a high melting point metal layer as an outer layer.
20. The low-melting-point metal layer is made of Sn or a metal containing Sn as a main component, and the high-melting-point gold layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component. Fuse element.
21. The fuse element according to claim 1, further comprising a heating element, wherein the fuse element is blown by heating the heating element.
22. A base member;
    A cover member fitted with the base member and covering the surface of the base member;
    A fuse element disposed between the base member and the cover member;
    The base member and the cover member are fuse elements made of a nylon plastic material.
23. The fuse element according to claim 22, wherein the plastic material is polyamide 46.
24. One of the base member and the cover member is provided with a side wall that intersects the surface direction of the surface of the base member and has an opening, and the other of the base member and the cover member is provided on the other side. 24. The fuse element according to claim 23, further comprising a fitting protrusion that projects outward from a surface intersecting the surface and is fitted into the opening of the side wall.
25. The base member or the cover member on which the fitting convex portion is formed protrudes outside from the surface intersecting the surface of the base member adjacent to the fitting convex portion, and the opening at the tip. 25. The fuse according to claim 24, wherein a locking claw bulging in a direction intersecting with the insertion direction is formed, and one or a plurality of locking pieces for locking the locking claw to the opening are formed. element.
26. The fuse element according to any one of claims 22 to 25, wherein the plastic material has a tracking resistance of 250 V or more.
27. The fuse element according to any one of claims 22 to 25, wherein the plastic material has a tracking resistance of 600 V or more.
28. The fuse element according to any one of claims 22 to 25, wherein the fuse element is a surface mount type.
29. The fuse element according to any one of claims 22 to 25, wherein the fuse element is a high melting point solder mainly composed of lead.
30. The fuse element according to claim 22, wherein the fuse element is a laminate including a high melting point metal layer and a low melting point metal layer.
31. The fuse element according to claim 30, wherein the fuse element has a covering structure in which an inner layer is a low melting point metal layer and an outer layer is a high melting point metal layer.
32. 32. The low-melting-point metal layer is made of Sn or a metal containing Sn as a main component, and the high-melting-point gold layer is made of Ag or Cu, or a metal containing Ag or Cu as a main component. Fuse element.
33. The fuse element according to any one of claims 22 to 25, further comprising a heating element, wherein the fuse element is melted by heating the heating element.
34. A base member;
    A cover member covering the surface of the base member;
    A fuse element disposed between the base member and the cover member;
    The base member and the cover member are fuse elements made of a plastic material having a tracking resistance of 250 V or more.
35. The fuse element according to claim 34, wherein the plastic material has a tracking resistance of 600V or more.
36. 36. The fuse element according to claim 34 or 35, wherein the plastic material is a nylon material.
37. 36. The fuse element according to claim 34 or 35, further comprising a heating element, wherein the fuse element is melted by heating the heating element.
38. A base member;
    A cover member fitted with the base member and covering the surface of the base member;
    A fuse element disposed between the base member and the cover member;
    One of the base member and the cover member is provided with a side wall that intersects the surface direction of the surface of the base member and has an opening, and the other of the base member and the cover member is provided on the other side. Protruding to the outside from the surface intersecting the surface, provided with a fitting convex portion to be fitted into the opening of the side wall,
    The fitting projection is formed with a fitting claw that bulges in a direction intersecting the insertion direction into the opening,
    A fuse element in which the opening is provided with a convex surface portion to which the fitting claw is engaged.
39. 39. The fuse element according to claim 38, wherein the fitting claw portion is formed with a tapered portion that is in sliding contact with the convex surface portion when inserted into the opening.
40. The base member and the cover member are each provided with the side wall in which the opening is formed on one of opposing sides, and the fitting convex part on the other of the opposing sides. 40. The fuse element according to 38 or 39.
41. 40. The fuse element according to claim 38 or 39, wherein the cover member is formed with a recess that is spaced apart from the fuse element and forms an internal space on an inner surface facing the surface of the base member.
42. The fuse element has terminal portions connected to electrodes formed on the external circuit board at both ends,
    In the cover member, the terminal part of the fuse element is exposed on a side different from the side on which the fitting convex part and / or the side wall is provided, and the insertion direction of the terminal part or the direction opposite to the insertion direction 40. The fuse element according to claim 38 or 39, wherein a leg portion for regulating the movement of the fuse element is formed.
43. 10. The fuse element according to claim 9, wherein the base member has a skirt portion located below a bent portion or an inclined portion of the fuse element connected to the terminal portion.
44. 43. The fuse element according to claim 42, wherein the base member has a skirt portion located below a bent portion or an inclined portion of the fuse element connected to the terminal portion.

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