Fuse and method for manufacturing fuse

Provided are a fuse having a structure that facilitates bending of a fuse element, and a method for manufacturing the fuse. In a fuse including a fuse element having a pair of terminal portions, a middle portion provided between the terminal portions, and a fusing portion provided in the middle portion, at least two or more of the middle portions are provided in the terminal portion, at least one of the middle portions is bent along a long direction such that a center side protrudes from long sides on both sides, and the middle portions are disposed to face each other when the terminal portion is folded at a bending point K2 of the terminal portion.

PRIORITY CLAIM

This application is a U.S. national phase of International Patent Application No. PCT/JP2020/045998, filed Dec. 10, 2020, which claims the benefit of priority from Japan Patent Application No. 2020-025798 filed Feb. 19, 2020, the contents of which are incorporated by reference.

FIELD OF THE INVENTION

The invention of the present application relates to a fuse to be used mainly for, for example, an electric circuit for an automobile, and a method for manufacturing the fuse.

BACKGROUND OF THE INVENTION

Conventionally, a fuse has been used to protect an electric circuit mounted on an automobile or the like and various electrical components connected to the electric circuit. Specifically, when an unintended overcurrent flows in the electric circuit, a fusing portion of a fuse element built in the fuse melts due to heat generated by the overcurrent, thereby protecting the various electrical components by preventing excess current from flowing.

Further, there are various types of such fuses depending on the application, and for example, a fuse described in Patent Literature 1 including a plurality of fusing portions is known.

The fuse described in Patent Literature 1 is of a type in which a fuse element is housed inside a casing, and includes the fuse element having a pair of terminal portions, two or more middle portions provided between the terminal portions, and fusing portions formed in each of the middle portions. Further, in such a fuse element, a single metal plate is punched to form the terminal portions, the two or more middle portions, and the fusing portions formed in each of the middle portions. Thereafter, the terminal portions are bent at bending points of the terminal portions such that the middle portions are disposed to face each other. However, the middle portion is formed in an elongated shape in order to provide the fusing portion, and thus, is easily bent and has lower strength than the terminal portion. Therefore, there is a possibility that the middle portion including the fusing portion is deformed at the time of bending formation of the fuse element as described above, so that the bending formation of the fuse element becomes difficult.

CITATIONS LIST

Patent Literature

Patent Literature 1: Japanese Patent Application No. 2019-224287

SUMMARY OF THE INVENTION

Technical Problems

Therefore, the invention of the present disclosure provides a fuse having a structure that facilitates bending formation of a fuse element, and a method for manufacturing the fuse.

Solutions to Problems

In order to solve the above problems, a fuse according to the invention of the present application is a fuse including a fuse element having a pair of terminal portions, a middle portion provided between the terminal portions, and a fusing portion provided in the middle portion, and is characterized in that at least two or more of the middle portions are provided in the terminal portion, at least one of the middle portions is bent along a long direction such that a center side protrudes from long sides on both sides, and the middle portions are disposed to face each other when the terminal portion is folded at a bending point of the terminal portion.

According to the above characteristic, a structure in which the middle portion is bent along the long direction such that the center side protrudes from the long sides on both the sides is provided. Thus, the strength of the middle portion in the long direction increases and the middle portion can be prevented from being bent and deformed so that bending formation of the fuse element becomes easy.

Furthermore, the fuse according to the invention of the present application is characterized in that the middle portions facing each other are bent so as to be separated from each other outward.

According to the above characteristic, the fusing portions of the middle portions facing each other can be separated from each other, and thus, the fusing portions are less likely to be thermally affected by each other and more easily exhibit desired fusing properties.

Furthermore, the fuse according to the invention of the present application is characterized in that a connection part between the middle portion and the terminal portion is folded in a direction orthogonal to the long direction of the middle portion such that the middle portions facing each other are separated from each other outward.

According to the above characteristic, the fusing portions of the middle portions facing each other can be separated from each other, and thus, the fusing portions are less likely to be thermally affected by each other and more easily exhibit desired fusing properties.

Further, according to a method for manufacturing a fuse of the invention of the present application, provided is a method for manufacturing a fuse including a fuse element having a pair of terminal portions, a middle portion provided between the terminal portions, and a fusing portion provided in the middle portion, the method being characterized by including: punching a single metal plate to form the pair of terminal portions and at least two or more of the middle portions between the terminal portions; bending the middle portion along a long direction such that a center side protrudes from long sides on both sides; and folding the terminal portion at a bending point of the terminal portion to dispose the middle portions so as to face each other.

According to the above characteristic, the middle portion is bent along the long direction such that the center side protrudes from the long sides on both the sides is provided. Thus, the strength of the middle portion in the long direction increases and the middle portion can be prevented from being bent and deformed so that the bending formation of the fuse element becomes easy.

Furthermore, according to the method for manufacturing a fuse of the invention of the present application, the middle portions facing each other are characterized by being bent so as to be separated from each other outward.

According to the above characteristic, the fusing portions of the middle portions facing each other can be separated from each other, and thus, the fusing portions are less likely to be thermally affected by each other and more easily exhibit desired fusing properties.

Furthermore, according to the method for manufacturing a fuse of the invention of the present application, a connection part between the middle portion and the terminal portion is characterized by being folded in a direction orthogonal to the long direction of the middle portion such that the middle portions facing each other are separated from each other outward.

According to the above characteristic, the fusing portions of the middle portions facing each other can be separated from each other, and thus, the fusing portions are less likely to be thermally affected by each other and more easily exhibit desired fusing properties.

Advantageous Effects of Invention

As described above, the bending formation of the fuse element is facilitated according to the fuse of the invention of the present application and the method for manufacturing the fuse.

REFERENCE SIGNS LIST

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, an embodiment of the invention of the present application will be described with reference to the drawings. Note that a shape, a material, and the like of each member of a fuse according to the embodiment described hereinafter are merely examples, and are not limited thereto.

InFIGS.1to3, a manufacturing process of a fuse element100of a fuse according to the invention of the present application will be described. Note thatFIG.1(a)is a plan view of the fuse element100in a developed state;FIG.1(b)is a plan view of the fuse element100in a state where a middle portion130is bent;FIG.2(a)is a side view of the fuse element100in a state where the middle portion130is bent;FIG.2(b)is a front view of the fuse element100in a state where the middle portion130is bent, the front view illustrating the vicinity of the middle portion130in an enlarged manner;FIG.2(c)is a cross-sectional view taken along line A-A illustrated inFIG.1(b);FIG.3(a)is a plan view of the completed fuse element100;FIG.3(b)is an overall perspective view of the completed fuse element100;FIG.3(c)is a side view of the completed fuse element100; andFIG.3(d)is a cross-sectional view taken along line B-B.

First, a flat plate material made of conductive metal such as copper or an alloy thereof is punched into a shape as illustrated inFIG.1(a)by a pressing machine or the like. In a single metal plate formed into a predetermined shape as illustrated inFIG.1(a), terminal portions110at both ends, flat middle portions130between the terminal portions110, and a plurality of fusing portions120are formed in the middle portion130. More specifically, the fusing portion120is constituted by a plurality of linear fusing points121whose widths are locally narrowed by providing small holes in the middle portion130. When an unintended overcurrent flows in an electric circuit or the like, each of the fusing points121generates heat and fuses to cut off the overcurrent. Note that the fusing portion120is not limited to being constituted by the linear fusing points121having narrow widths, and can adopt any configuration, such as local arrangement of a metal material which is likely to be fused in the middle portion130, if the overcurrent can be cut off by heat generation and fusing when the unintended overcurrent flows in the electric circuit or the like.

Next, as illustrated inFIGS.1(b)and2, a connection part131between the middle portion130and the terminal portion110is folded upward at a bending line L1toward a Z direction which is a longitudinal direction orthogonal to an X direction which is a long direction of the middle portion130. Then, the middle portion130is connected so as to slightly swell upward from the terminal portion110. The bending line L1extends in a Y direction as a short direction of the middle portion130orthogonal to the X direction and the Z direction. Note that this process of folding the connection part131is manually performed by a person or automatically performed by a bending machine.

As illustrated inFIGS.1(b)and2, the middle portion130is bent such that a center side133protrudes in the Z direction from long sides132on both sides along the X direction which is the long direction of the middle portion130. Note that the middle portion130has a shape in which the center side133is curved so as to smoothly swell in the Z direction from the long sides132on both the sides, but may have a shape in which the center side133may is pointed like a substantially triangular shape as long as the center side133is bent in the Z direction more than the long sides132on both sides without being limited thereto. In addition, the process of bending the center side133of the middle portion130is manually performed by a person or automatically performed by a bending machine. Note that the process of folding the connection part131and the process of bending the center side133of the middle portion130may be simultaneously performed by the bending machine. Alternatively, the process of folding the connection part131may be performed first, and then, the process of bending the center side133of the middle portion130may be performed. Alternatively, the process of bending the center side133of the middle portion130may be performed first, and then, the process of bending the connection part131may be performed.

Next, when the laterally arranged terminal portions110are folded so as to vertically overlap each other at a bending line K1at a bending point K2approximately at the center of the terminal portion110, the fuse element100is formed in a three-dimensional shape as illustrated inFIG.3. Further, the bending line K1is substantially parallel to the X direction which is the long direction of the middle portion130, and the fuse element100has a line-symmetrical shape at the bending line K1. Therefore, when the upper and lower terminal portions110are folded at the bending point K2as illustrated inFIG.3, the middle portions130are disposed so as to face each other vertically. Note that this process of folding the terminal portion110is manually performed by a person or automatically performed by a bending machine, and the one terminal portion110is bent at the bending point K2so as to be folded back toward the other adjacent terminal portion110.

Here, since the middle portion130is long, the strength in the long direction is weak. In addition, since the middle portion130includes the fusing portion120, the strength in the long direction is weak. Therefore, the middle portion130is bent such that the center side133protrudes from the long sides132on both the sides along the X direction which is the long direction in the invention of the present application, and thus, the strength of the middle portion130in the long direction is increased. Therefore, when the terminal portion110is folded to bend and form the fuse element100, the middle portion130can be prevented from being bent and deformed. That is, the fuse element100of the fuse according to the invention of the present application has a structure in which the middle portion130is bent along the X direction which is the long direction so as to have the center side133protruding from the long sides132on both the sides, thereby facilitating the bending formation of the fuse element100. Further, according to a method for manufacturing the fuse of the invention of the present application, a process of bending the middle portion130along the X direction which is the long direction such that the center side133protrudes from the long sides132on both the sides is provided, thereby facilitating the bending formation of the fuse element100. Furthermore, since the middle portion130can be prevented from being deformed at the time of bending formation of the fuse element100, it is possible to increase a processing speed of the fuse element100to improve the manufacturing efficiency of the fuse.

The fuse element100illustrated inFIGS.1to3includes a total of four middle portions130but may include any number of middle portions130as long as two or more middle portions130are provided without being limited thereto. Further, in the fuse element100illustrated inFIGS.1to3, all the middle portions130are bent such that the center side133protrudes from the long sides132on both the sides, but the present invention is not limited thereto. When at least one or more middle portions130are bent such that the center side133protrudes from the long sides132on both the sides, not only the strength of the bent middle portion130is improved but also the entire strength including the vicinity of the connecting point between the middle portion130with the improved strength and the terminal portion110is improved. Thus, the middle portion130and the periphery thereof can be prevented from being bent and deformed at the time of bending formation of the fuse element100, so that the bending formation of the fuse element100becomes easy.

Furthermore, according to the method for manufacturing the fuse of the invention of the present application, each of the middle portions130is bent along the X direction which is the long direction of the middle portion130such that the center side133protrudes in the Z direction from the long sides132on both the sides in a developed state before the fuse element100is folded at the bending point K2of the terminal portion110as illustrated inFIGS.1and2. That is, the middle portions130to be disposed so as to face each other are bent so as to protrude in the same direction. Therefore, when the terminal portions110are folded such that the terminal portions110overlap at the bending point K2of the terminal portion as illustrated inFIG.3(d), the middle portions130facing each other in the longitudinal direction are bent so as to be separated from each other outward. Then, the fusing portions120of the middle portions130facing each other can be separated from each other, and thus, the fusing portions120are less likely to be thermally affected by each other and more easily exhibit desired fusing properties.

Next, according to the method for manufacturing the fuse of the invention of the present application, each of the connection parts131between the middle portion130and the terminal portion110is folded upward at the bending line L1toward the Z direction which is the longitudinal direction orthogonal to the X direction which is the long direction of the middle portion130in the developed state before the fuse element100is folded at the bending point K2of the terminal portion110as illustrated inFIGS.1and2. That is, the connection parts131of the middle portions130to be disposed so as to face each other are folded in the same Z direction. Therefore, when the terminal portions110are folded such that the terminal portions110overlap at the bending point K2of the terminal portion as illustrated inFIG.3(c), the middle portions130facing each other in the longitudinal direction are separated from each other outward. Then, the fusing portions120of the middle portions130facing each other can be separated from each other, and thus, the fusing portions120are less likely to be thermally affected by each other and more easily exhibit desired fusing properties.

Further, the middle portion130illustrated inFIG.2(b)is bent such that the center side133protrudes to the outside of the connection part131more than the long sides132on both the sides, but the middle portion130may be bent such that the center side133protrudes to the inside of the connection part131more than the long sides132on both the sides without being limited thereto. However, the middle portion130is bent such that the center side133protrudes to the outside of the connection part131more than the long sides132on both the sides so that bending directions of the center side133, the long sides132, and the connection part131are smoothly continued in the same direction as illustrated inFIG.2(b). Thus, a locally thinned part is not generated in such a bent part, and the strength is not locally weakened. As a result, the entire strength including the connection part131between the middle portion130and the terminal portion110is improved. Thus, the middle portion130and the periphery thereof can be prevented from being bent and deformed at the time of bending formation of the fuse element100, so that the bending formation of the fuse element100becomes easy.

Note that the fuse element100is formed by punching the flat plate material made of conductive metal, such as copper or an alloy thereof, into the shape as illustrated inFIG.1(a)with the pressing machine or the like. This plate material includes a single plate material in which only a plate thickness of the middle portion130including the fusing portion120is thin and a plate thickness of the terminal portion110is large, that is, the thickness is not uniform and a single plater material (profile) in which only a plate thickness of a part forming the fusing portion120is thinner than a plate thickness of the other part (the terminal portion110and the like). Therefore, it is unnecessary to separately prepare the fusing portion120made of a plate material having a small plate thickness and the terminal portion110made of a plate material having a large plate thickness and weld the both to each other, and the fuse element100can be easily manufactured.

Furthermore, the middle portion130made of the plate material having a small plate thickness is easily bent and deformed at the time of bending formation of the fuse element100, but the strength of the middle portion130can be improved according to the invention of the present application. Thus, the middle portion130and the periphery thereof can be effectively prevented from being bent and deformed, and the bending formation of the fuse element100becomes easy. Note that the fuse element100is made of the material (profile) in which only the thickness of the part constituting the middle portion130including the fusing portion120is thinner than the thickness of the other part (the terminal portion110and the like), but may be made of a plate material in which a plate thickness of the part forming the middle portion130including the fusing portion120is the same as a plate thickness of the other part (the terminal portion110and the like), that is, the thickness is uniform without being limited thereto.

Next, a method for assembling the fuse400of the invention of the present application will be described with reference toFIG.4.FIG.4(a)is an overall perspective view illustrating members constituting the fuse400in an exploded manner, andFIG.4(b)is an overall perspective view of the completed fuse400.

As illustrated inFIG.4(a), first, a casing-divided piece200made of synthetic resin is disposed with an opening250facing upward. Further, the terminal portions110of the fuse element100are placed on placement surfaces224of side walls220on both sides of the casing-divided piece200. The middle portion130of the fuse element100is accommodated in the opening250of the casing-divided piece200. Next, the casing-divided piece200having the same shape as the lower casing-divided piece200is fitted from above the lower casing-divided piece200with the opening250facing downward. Specifically, the placement surface224of the side wall220of the upper casing-divided piece200is applied toward the terminal portion110, and the terminal portion110of the fuse element100is vertically sandwiched between the placement surface224of the upper casing-divided piece200and the placement surface224of the lower casing-divided piece200.

Next, a frame-shaped fixing member300is attached to a casing290so as to surround the periphery of the terminal portion110from both sides in order to firmly fix the casing290constituted by the upper and lower casing-divided pieces200so as not to be detached. Specifically, the frame-shaped fixing member300is inserted through the terminal portion110, and then, press-fitted into an outer surface222of the casing290. The outer surfaces222of the upper and lower casing-divided pieces200are configured to continuously make a round over the periphery of the casing-divided pieces200when the upper and lower casing-divided pieces200are assembled. Therefore, the upper and lower casing-divided pieces200are firmly fixed to each other by press-fitting the frame-shaped fixing member300along the upper and lower outer surfaces222. Note that the frame-shaped fixing member300is an annular body made of metal, and has the same shape so as to correspond to the outer surfaces222of the casing290. In addition, the frame-shaped fixing member300is slightly smaller than the outer surfaces222such that the frame-shaped fixing member300can be press-fitted into the outer surfaces222.

In this manner, the fuse element100and the casing290are assembled in a state where the fusing portion120of the fuse element100is accommodated inside, whereby the fuse400is completed as illustrated inFIG.4(b). Further, the terminal portion110of the fuse element100protrudes outward from the side wall220of the casing290so as to be electrically connected to an external electric circuit. When an overcurrent flows through the external electric circuit, the fusing portion120accommodated in the casing290fuses to cut off the overcurrent, thereby protecting the electric circuit.

Note that the casing290includes the two upper and lower casing-divided pieces200having a substantially cubic shape, but the casing290may have any configuration as long as the fuse element100can be assembled in a state where the fusing portion120is accommodated inside without being limited thereto.

Note that the fuse and the method for manufacturing the fuse of the invention of the present application are not limited to the above embodiment, and various modifications and combinations can be made within the scope of the claims and the scope of the embodiment, and these modifications and combinations are also included in the scope of the right.