JP7704438B2 - Manufacturing method for blade type fuse - Google Patents

Description

The present invention relates to a blade-type fuse used, for example, to protect electrical circuits in automobiles, and a method for manufacturing the blade-type fuse.

Conventionally, blade-type fuses such as those shown in Patent Document 1 have been used to protect electrical circuits mounted on automobiles and various electrical equipment connected to the electrical circuits. In detail, a blade-type fuse has a roughly U-shaped fusing portion and a pair of terminal portions that are connected to the fusing portion and extend downward, with an external connection terminal connected to the lower half of the pair of terminal portions. When an abnormality occurs in the electrical circuit, the fusing portion of the blade-type fuse melts due to an abnormal current, cutting off the electrical circuit. In addition, a fixing hole for fixing the housing is provided on the upper half of the pair of terminal portions, and the fixing shaft of the housing is inserted into the fixing hole and crimped (cold crimping, etc.).

In recent years, there has been a demand for thinner blade-type fuses. To reduce the height of a blade-type fuse, the vertical height of the terminal section can be reduced. However, if the vertical height of the terminal section is reduced, there is no space to arrange fixing points such as fixing holes for fixing the housing and connection points for connecting external connection terminals, and they end up interfering with each other, making it difficult to reduce the vertical height of the terminal section.

Patent Publication 2013-157237

In view of the above problems, the present invention provides a blade-type fuse that has a low profile while having fixing points for fixing the housing and connection points for connecting external connection terminals without interfering with each other, and a method for manufacturing the blade-type fuse.

The blade-type fuse of the present invention is a blade-type fuse comprising a pair of terminal portions connected to external connection terminals, a fusing portion connected between the terminal portions, and a housing that contains the fusing portion, and is characterized in that the terminal portions are configured so that the external contacts that connect the terminal portions to the external connection terminals are arranged side-by-side with a portion of the fusing portion, and the upper end of the terminal portion is inserted into a fixing hole at the upper end of the housing and crushed, so that it is fixed within the fixing hole.

According to the above features, the external contacts that connect to the external connection terminals are arranged side by side with the fusing portion, allowing the vertical height of the terminal portion to be reduced. Furthermore, since the upper end of the terminal portion is not the portion that connects to the external connection terminal, even if the upper end of the terminal portion is used as a fixing point with the housing, it does not interfere with the connection point that connects the external connection terminal. As a result, a low height can be achieved while providing a fixing point for fixing the housing and a connection point for connecting the external connection terminal without interfering with each other.

The blade-type fuse of the present invention is characterized in that it comprises a first connection point where the fusing portion is connected to one of the terminal portions, and a second connection point where the fusing portion is connected to the other of the terminal portions, and the first connection point and the second connection point are disposed above and below the center of the fusing portion at different heights.

By separating the first and second connection points vertically, the fusing section can be arranged in a wide vertical space with a relatively free shape while taking thermal balance into consideration. Therefore, even if the width is narrowed, heat does not concentrate locally compared to conventional methods, and thermal balance can be maintained, making it possible to obtain the desired fusing characteristics.

The blade-type fuse of the present invention is characterized in that the melting portion has a shape that is point-symmetrical with respect to the central portion.

The above features maintain thermal balance and stabilize fusing characteristics.

The blade-type fuse of the present invention comprises a first external contact at which one of the terminal portions is connected to the external connection terminal, and a second external contact at which the other of the terminal portions is connected to the external connection terminal, and is characterized in that the height at which the first external contact and the second external contact are arranged is equal to the height at which the center of the fusing portion is arranged, and the distance between the first connection point and the first external contact is equal to the distance between the second connection point and the second external contact.

The above features allow the overall length of the fusing portion to be long even if the width of the fusing portion is narrowed, making it compatible with low-rated blade-type fuses. Furthermore, because the distance between the first external contact and the first connection point is equal to the distance between the second external contact and the second connection point, the resistance of the path on the terminal through which current flows is equal, and there is no directionality relative to the external contacts. In other words, there is no directionality in the installation of the blade-type fuse, making it easier to install in a housing such as a fuse box.

The blade-type fuse of the present invention is characterized in that the width of the melting portion is narrower than the width of the terminal portion.

Because of the above characteristics, it is difficult to narrow the width of the terminal part from the standpoint of compatibility and narrowing the width, so the width of the fusing part is narrowed, thereby narrowing the width of the blade-type fuse.

The method for manufacturing a blade-type fuse of the present invention is a method for manufacturing a blade-type fuse comprising a pair of terminal portions connected to external connection terminals, a fusing portion connected between the terminal portions, and a housing that accommodates the fusing portion, wherein the terminal portions are configured so that external contacts that connect the terminal portions and the external connection terminals are arranged side-by-side with a portion of the fusing portion, and the upper end of the terminal portion is inserted into a fixing hole at the upper end of the housing and crushed to fix it within the fixing hole.

According to the above features, the external contacts that connect to the external connection terminals are arranged side by side with the fusing portion, allowing the vertical height of the terminal portion to be reduced. Furthermore, since the upper end of the terminal portion is not the portion that connects to the external connection terminal, even if the upper end of the terminal portion is used as a fixing point with the housing, it does not interfere with the connection point that connects the external connection terminal. As a result, a low height can be achieved while providing a fixing point for fixing the housing and a connection point for connecting the external connection terminal without interfering with each other.

The manufacturing method of the blade-type fuse of the present invention is characterized in that the upper end of the terminal portion is fixed within the fixing hole by first crushing the upper end of the housing inserted into the fixing hole with a first punching member having a tip smaller than the fixing hole, and then crushing the upper end of the housing with a second punching member having a tip larger than the first punching member.

According to the above feature, first, the upper end of the terminal portion is crushed by the first punching member, thereby temporarily fixing and positioning the terminal portion and the fixing hole of the housing, and then, the upper end of the terminal portion is crushed by the second punching member, thereby enabling it to be accurately fixed in the desired position.

As described above, the blade-type fuse and the method for manufacturing the blade-type fuse of the present invention can achieve a low profile while providing fixing points for fixing the housing and connection points for connecting the external connection terminals without interfering with each other.

FIG. 2A is a front view of a blade-type fuse according to the present invention, and FIG. 2B is a front view of the blade-type fuse with the housing removed. FIG. 2 is an overall perspective view of a blade-type fuse housed in a housing; 2A is a cross-sectional view taken along line A-A in FIG. 2, showing a blade-type fuse housed in a housing; and FIG. 2B is a cross-sectional view taken along line B-B in FIG. 2, showing a blade-type fuse housed in a housing. FIG. 3( a ) is a cross-sectional view showing the housing and the container removed.

REFERENCE SIGNS LIST 100 Terminal portion 200 Fusing portion 210 First connection point 220 Second connection point 230 Center portion 300 Housing 400 Blade-type fuse 410 First external contact 420 Second external contact

The following describes an embodiment of the present invention with reference to the drawings. Note that the shapes and materials of the components of the blade-type fuse in the embodiment described below are merely examples and are not intended to be limiting.

First, the blade-type fuse 400 of the present invention is shown in Figure 1. Figure 1(a) is a front view of the blade-type fuse 400, and Figure 1(b) is a front view of the blade-type fuse 400 with the housing 300 removed.

As shown in FIG. 1, the blade-type fuse 400 includes a pair of terminals 100 and a fusing portion 200 arranged side by side between the terminals 100. The blade-type fuse 400 also includes a housing 300 that houses the fusing portion 200 inside. The housing 300 is made of an insulating material such as synthetic resin. The terminals 100 are made of a metal conductor and are electrically connected to an external connection terminal 800, which will be described later. Specifically, the terminals 100 extend linearly in the vertical direction from the lower end 110 to the upper end 120 and include a flat main body 130. The main body 130 is configured in a plate shape so as to be inserted into the external connection terminal 800, which will be described later, and includes a rising portion 132 that is a connection point with the fusing portion 200. The rising portion 132 of the main body 130 is thinner than the thickness of the main body 130 and protrudes inward from an inner end 131 of the main body 130. The width from the outermost end 133 of the terminal portion 100 to the boundary between the fusion portion 200 and the rising portion 132, that is, the width of the terminal portion 100, is L1. The main body portion 130 of the terminal portion 100 is the portion that connects to the external connection terminal 800, and in order to provide compatibility so that it can be connected to various types of external connection terminals, it is difficult to make the width L1 of the terminal portion 100 any narrower. Furthermore, since the terminal portion 100 is narrowed to its limit, from the perspective of ensuring strength, the main body portion 130 of the terminal portion 100 does not have fixing holes or the like that have been conventionally used to fix the housing 300.

In addition, in the blade-type fuse 400, the terminal portion 100 having an external contact to be connected to the external connection terminal 800 described later and the fusing portion 200 are arranged side by side, so that the height of the terminal portion 100 in the vertical direction is low. Therefore, the terminal portion 100 with a low height can only secure a space for connecting the external connection terminal 800, and it is difficult to secure a space for arranging a fixing part such as a fixing hole for fixing the housing as in the conventional case. Therefore, in the blade-type fuse 400 of the present invention, the upper end 120 of the terminal portion 100 is configured to be inserted into the fixing hole 340 at the upper end of the housing 300, and the upper end 120 of the inserted terminal portion 100 is crushed from above by a punching member, so that the upper end 120 of the terminal portion 100 is pressed into the fixing hole 340, and the terminal portion 100 and the housing 300 are firmly fixed. The upper end 120 of the terminal portion 100 is flattened, so that the upper end 120 of the terminal portion 100 is recessed downward within the fixing hole 340, as shown in FIG. 2. Furthermore, the upper end 120 of the terminal portion 100 is not the part that connects to the external connection terminal 800, so even if the upper end 120 of the terminal portion 100 is used as a fixing point with the housing 300, it does not interfere with the connection point that connects the external connection terminal. As a result, a low profile can be achieved while having a fixing point for fixing the housing and a connection point for connecting the external connection terminal without interfering with each other.

In addition, when fixing the upper end 120 of the terminal portion 100 to the fixing hole 340, as shown in FIG. 1, the upper end 120 of the terminal portion 100 may be crushed from above by a first punching member 710 having a tip 711 smaller than the fixing hole 340. Next, the upper end 120 of the terminal portion 100 may be crushed from above by a second punching member 720 having a tip 721 larger than the tip 711 of the first punching member 710. In this way, first, the upper end 120 of the terminal portion 100 is crushed by the first punching member 710, so that the upper end 120 of the terminal portion 100 and the fixing hole 340 of the housing 300 are temporarily fixed and positioned, and then the upper end 120 of the terminal portion 100 is crushed by the second punching member 720, so that the terminal portion 100 can be accurately fixed at the desired position. Then, by crushing in two stages, the load on the terminal portion 100 can be reduced and the terminal portion 100 can be prevented from buckling. The first punching member 710 and the second punching member 720 are any member made of a metal or the like harder than the terminal portion 100. The tip 711 of the first punching member 710 is preferably an elliptical sharp shape. The tip 721 of the second punching member 720 is smaller than the fixing hole 340. Although the first punching member 710 and the second punching member 720 crush the upper end 120 of the terminal portion 100 in two stages, this is not limited to the above, and the upper end 120 of the terminal portion 100 may be crushed in three or more stages using any punching member.

In addition, the positioning step 320 of the housing 300, which will be described later, is also the part that is supported by the jig that holds the blade-type fuse 400 when the upper end 120 of the terminal portion 100 is crushed by the punching member. Furthermore, since the housing 300 side is held rather than the terminal portion 100 side when crushed by the punching member, the force received from the punching member is less likely to be applied to the terminal portion 100, and buckling of the terminal portion 100 can be prevented.

The fusing portion 200 is arranged side by side with the terminal portions 100 on both sides, and is housed in a space surrounded by a straight line connecting the lower ends 110 on both sides of the terminal portion 100, a straight line connecting the upper ends 120 on both sides of the terminal portion 100, and the inner end 131 of the main body portion 130. The fusing portion 200 is entirely made of a low melting point metal such as tin, silver, lead, nickel, or an alloy thereof, and is configured to melt when an abnormal current flows. Specifically, the fusing portion 200 is substantially S-shaped and includes a first connection point 210 connected to the rising portion 132 of one terminal portion 100 and a second connection point 220 connected to the rising portion 132 of the other terminal portion 100. Furthermore, the fusing portion 200 is shaped point-symmetrical with respect to the center portion 230. In other words, even if the fusion portion 200 is rotated 180 degrees around the center portion 230, the shape of the fusion portion 200 before and after the rotation is the same.

In this way, by making the fusing portion 200 point-symmetrical about the central portion 230, thermal balance is maintained and the fusing characteristics are stabilized. Note that, although the fusing portion 200 has a roughly S-shape (a shape with one bent portion above and one bent portion above the central portion 230) centered on the central portion 230, the shape is not limited to this, and the fusing portion 200 can have any shape, such as a shape with two or more bent portions above and below the central portion 230, so long as the shape is point-symmetrical about the central portion 230. Furthermore, although the fusing portion 200 has a shape point-symmetrical about the central portion 230, the shape is not limited to this, and the fusing portion 200 can have any shape.

Here, by arranging the terminal portions 100 on both sides side by side with the fusing portion 200, the overall height of the blade-type fuse 400 can be reduced. However, because the terminal portions 100 are arranged on both sides, it is necessary to prevent the width L3 of the blade-type fuse 400 from becoming too large. However, as mentioned above, it is difficult to make the width L1 of the terminal portion 100 any narrower from the standpoint of compatibility. For this reason, the width L2 of the fusing portion 200, i.e., the width L2 between the first connecting point 210 and the second connecting point 220, is narrowed to narrow the width L3 of the blade-type fuse 400.

In addition, if the width L2 of the fusion portion 200 is narrowed, and the fusion portion is roughly U-shaped as in the conventional case, the U-shaped portion will be crushed, and the length of the fusion portion required to obtain the specified resistance value will not be obtained, resulting in the problem that the specified fusion characteristics cannot be obtained.

Therefore, in the blade-type fuse 400 of the present invention, the first connection point 210 and the second connection point 220 are arranged at different heights above and below the central portion 230. Specifically, the first connection point 210 of the fusing portion 200 is arranged at a height H1 from the lower end 110 of the terminal portion 100, the second connection point 220 of the fusing portion 200 is arranged at a height H2 from the lower end 110 of the terminal portion 100, and the central portion 230 of the fusing portion 200 is arranged at a height H3 from the lower end 110 of the terminal portion 100. The height H1 at which the first connection point 210 is arranged is lower than the height H3 at which the central portion 230 is arranged, and the height H2 at which the second connection point 220 is arranged is higher than the height H3 at which the central portion 230 is arranged. In this way, by separating the first connection point 210 and the second connection point 220 vertically, the fusing part 200 can be arranged in a relatively free shape in a wide vertical space while taking thermal balance into consideration. This means that heat is not concentrated locally compared to conventional methods, and thermal balance can be maintained, making it possible to obtain the desired fusing characteristics.

In addition, narrowing the width L2 of the fusing portion 200 limits the shape of the fusing portion 200, particularly the overall length of the fusing portion 200, because the distance between the first connecting point 210 and the second connecting point 220 becomes closer. In particular, when lowering the rated value of the blade-type fuse 400, it is necessary to lengthen the overall length of the fusing portion 200 to increase the resistance value, but narrowing the width L2 of the fusing portion 200 makes it difficult to lengthen the overall length of the fusing portion 200. Therefore, in the present invention, the first connecting point 210 and the second connecting point 220 are arranged at different heights above and below the central portion 230. In this way, by separating the first connecting point 210 and the second connecting point 220 vertically, the shape of the fusing portion 200 can be changed so that the length between the first connecting point 210 and the second connecting point 220, that is, the overall length of the fusing portion 200, is stretched vertically to increase its length. Therefore, even if the width L2 of the fusing part 200 is narrowed, the overall length of the fusing part 200 can be made long, and it can also accommodate low-rated blade-type fuses 400.

In the blade-type fuse 400 of the present invention, the width L2 of the fusion portion 200 is narrower than the width L1 of the terminal portion 100, so the width L3 of the blade-type fuse 400 can be narrowed. In addition, since the fusion portion 200 has a shape that is point-symmetrical with respect to the center portion 230, the vertical distance H5 (H5 = H3 - H1) between the center portion 230 of the fusion portion 200 and the first connecting point 210 is equal to the vertical distance H6 (H6 = H2 - H3) between the center portion 230 of the fusion portion 200 and the second connecting point 220. In addition, the height H2 at which the second connection point 220 of the fusion portion 200 is located is higher than the height H1 at which the first connection point 210 of the fusion portion 200 is located, but this is not limited thereto, and the shape of the fusion portion 200 may be determined so that the height H1 at which the first connection point 210 of the fusion portion 200 is located is higher than the height H2 at which the second connection point 220 of the fusion portion 200 is located.

Next, referring to Figures 2 to 4, the state in which the blade-type fuse 400 is housed in the container 900 and connected to the external connection terminal 800 will be described. Note that Figure 2 is an overall perspective view of the blade-type fuse 400 housed in the container 900, Figure 3(a) is a cross-sectional view taken along line A-A in Figure 2, showing the blade-type fuse 400 housed in the container 900, Figure 3(b) is a cross-sectional view taken along line B-B in Figure 2, showing the blade-type fuse 400 housed in the container 900, and Figure 4 is a cross-sectional view of Figure 3(a) with the housing 300 and container 900 removed.

First, as shown in FIG. 2, the housing 900 is a so-called fuse box, and includes a housing space 910 large enough to house the blade-type fuse 400, and a pair of external connection terminals 800 inside the housing space 910. Positioning portions 920 protruding inward are provided on both sides of the housing space 910. The external connection terminals 800 are in the form of a so-called tuning fork terminal with two clamping pieces 810, and are electrically connected to an external electric circuit or the like. When the blade-type fuse 400 is housed and attached in the housing 900, the blade-type fuse 400 is inserted from above into the housing space 910 that opens upward. The blade-type fuse 400 is then pushed downward so that the terminal portion 100 of the blade-type fuse 400 is inserted between the clamping pieces 810 of the external connection terminals 800. Then, the positioning step 320 on the housing 300 of the blade-type fuse 400 abuts against the positioning portion 920 of the container 900, so that the blade-type fuse 400 is positioned so that it is not pushed any further into the container space 910. As shown in FIG. 3, the clamping pieces 810 of the external connection terminal 800 clamp and fix the terminal portion 100 from both sides, so that the blade-type fuse 400 accommodated in the container space 910 of the container 900 maintains an electrically connected state with the external connection terminal 800.

3 and 4, the position of the blade-type fuse 400 is fixed by the positioning step 320, so that the position where the one external connection terminal 800 and one terminal portion 100 come into contact and are electrically connected, i.e., the position of the first external contact 410, is also fixed. Similarly, the position where the other external connection terminal 800 and the other terminal portion 100 come into contact and are electrically connected, i.e., the position of the second external contact 420, is also fixed. In addition, in the blade-type fuse 400 of the present application, when it is housed in a housing 900 such as a fuse box, the first external contact 410 and the second external contact 420 are arranged side by side with a part of the fusing portion 200, so that a low profile can be achieved. Another feature of the low profile is that the first external contact 410 and the second external contact 420 are arranged above the lower surface 301 of the housing 300.

The current flowing through the electric circuit connected to the external connection terminal 800 flows from one external connection terminal 800 to the terminal unit 100 via the first external contact 410, and then flows from the first external contact 410 to the first connection point 210 of the fusion unit 200 along the path M1 on the terminal unit 100. Furthermore, the current flowing to the fusion unit 200 flows from the second connection point 220 of the fusion unit 200 to the second external contact 420 along the path M2 on the terminal unit 100, and then flows to the other external connection terminal 800 via the second external contact 420. If an abnormal current flows, the fusion unit 200 melts to cut off the current, thereby protecting the electric circuit connected to the external connection terminal 800.

Here, the first external contact 410 is disposed at a height H4 from the lower end 110, and the second external contact 420 is also disposed at a height H4 from the lower end 110. Furthermore, the height H4 at which the first external contact 410 and the second external contact 420 are disposed is equal to the height H3 at which the central portion 230 of the fusing portion 200 is disposed. Therefore, the vertical distance between the first external contact 410 and the first connecting point 210 of the fusing portion 200 is equal to the vertical distance H5 between the central portion 230 of the fusing portion 200 and the first connecting point 210. Similarly, the vertical distance between the second external contact 420 and the second connecting point 220 of the fusing portion 200 is equal to the vertical distance H6 between the central portion 230 of the fusing portion 200 and the second connecting point 220. The vertical distance H5 between the first external contact 410 and the first connection point 210 of the fusion portion 200 is equal to the vertical distance H6 between the second external contact 420 and the second connection point 220 of the fusion portion 200 (distance H5 = distance H6). In addition, since the connection structure between the terminal portions 100 on both sides and each external connection terminal 800 is the same, the horizontal distance L5 between the first external contact 410 and the first connection point 210 of the fusion portion 200 is equal to the horizontal distance L6 between the second external contact 420 and the second connection point 220 of the fusion portion 200 (distance L5 = distance L6).

In this way, the distance between the first external contact 410 and the first connection point 210 (specifically, the vertical distance H5 and the horizontal distance L5, respectively) is equal to the distance between the second external contact 420 and the second connection point 220 (specifically, the vertical distance H6 and the horizontal distance L6, respectively), so the length of the path M1 of the current flowing from the first external contact 410 to the first connection point 210 is equal to the length of the path M2 of the current flowing from the second connection point 220 to the second external contact 420. Therefore, the resistance values of the paths M1 and M2 on the terminal portion 100 through which the current flows are equal, so there is no directionality with respect to the external contacts, that is, there is no directionality in the installation of the blade-type fuse 400, making it easier to install it in a housing such as a fuse box.

Note that, although the linear paths M1 and M2, which are the shortest distances, have been exemplified as paths through which the current flows, the present invention is not limited to these, and the current can flow along any path between the first external contact 410 and the first connection point 210, and any path between the second external contact 420 and the second connection point 220 on the terminal portion 100. Since the distance between the first external contact 410 and the first connection point 210 and the distance between the second external contact 420 and the second connection point 220 are equal, the resistance of the path is basically approximately equal regardless of the path along which the current flows, and therefore there is no directionality with respect to the external contacts. In other words, there is no directionality in the installation of the blade-type fuse 400, making it easier to install it in a housing such as a fuse box.

The external connection terminal 800 is in the form of a tuning fork terminal with a pair of clamping pieces 810, but is not limited to this and may be in any form as long as it can come into contact with the terminal portion 100 and be electrically connected. In addition, to fix the position of the attached blade-type fuse 400, the positioning step portion 320 of the blade-type fuse 400 abuts against the positioning portion 920 of the container 900, but is not limited to this and may be in any suitable configuration as long as it can fix the position of the blade-type fuse 400.

Furthermore, the blade-type fuse of the present invention is not limited to the above examples, and various modifications and combinations are possible within the scope of the claims and the scope of the embodiments, and these modifications and combinations are also included in the scope of the rights.

Claims (1)

A method for manufacturing a blade-type fuse comprising a pair of terminal portions to be connected to external connection terminals, a fusing portion connected between the terminal portions, and a housing for accommodating the fusing portion, comprising the steps of:
the terminal portion is configured such that an external contact, which connects the terminal portion and the external connection terminal, is arranged side by side with a part of the fusing portion;
The upper end of the terminal portion is inserted into a fixing hole at the upper end of the housing and crushed to be fixed within the fixing hole ,
Fixing the upper end of the terminal portion in the fixing hole includes:
First, a first punching member having a tip smaller than the fixing hole is used to crush an upper end of the housing inserted into the fixing hole;
Next, the upper end of the housing is crushed with a second punching member having a tip larger than that of the first punching member .

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