JP2010108786A - High-current fuse - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-current fuse for preventing fracture of a fuse link in thermal shock evaluation, absorbing stress upon assembling, and preventing secondary short circuit in fusing. <P>SOLUTION: The high-current fuse includes a fusible fuse link 5, which is formed of a pair of thick parts 11, 11 and a pair of erection parts 12, 12 and is surrounded by a reinforcing member 10 of an approximately square frame shape. A stress absorption part 40 for absorbing stress concentration is formed between bolt assembling through-holes 2d, 2d of tab shaped terminal plates 2, 2 and the thick parts 11 along the thick parts 11. By forming the stress absorption parts 40, the stress concentration, which is generated by a difference in thermal expansion rates of an evaluation box and the tab shaped terminal plates 2, 2, is absorbed to prevent fracture of the fuse link 5 in the thermal shock evaluation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high-current fuse used in an automobile, and more particularly to a fuse that absorbs stress applied to a fuse element.

As a large current fuse used in an automobile, the one shown in FIG. 6 has been proposed (see Patent Document 1).
This large-current fuse has a fusible fuse link 5 installed between opposite ends 2a and 2a of tab-like terminal plates 2 and 2 which are paired on the left and right in the figure, and is located in the middle of the fuse link 5. Is provided with a fusible part 6 which is melted by the heat generated by the fuse itself. Bolt assembly holes 2d and 2d for inserting screws, bolts or the like (not shown) are formed on the other end 2c side of the terminal plate 2, respectively.
JP-A-11-213853

  A resin reinforcing member 10 is integrally formed around the fuse link 5 in a substantially rectangular frame shape. The reinforcing member 10 is provided in parallel with the longitudinal direction of the fuse link 5 and the pair of thick portions 11 and 11 that improve the strength in the direction intersecting the longitudinal direction of the fuse link 5. It consists of a pair of erection parts 12 and 12 to improve. A transparent cover 30 having a U-shaped cross section is attached from the P direction so as to cover the fuse link 5. Since the pair of side wall plates 31, 31 of the transparent cover 30 having a U-shaped cross section are also transparent, the fuse link 5 can be directly viewed through the side wall plate 31. Therefore, the state of the fusible part 6 of the fuse link 5 can be confirmed at a glance.

  Since such a large current fuse is used in a place where a temperature change is a problem, thermal shock evaluation is performed to evaluate whether the fuse has a performance corresponding to the temperature change.

The method of thermal shock evaluation is performed as shown in FIG.
First, the large-current fuse 1 (FIG. 6) that is the subject of thermal shock evaluation is placed in the evaluation box 50. Two upright bolts 51, 51 are provided on the bottom surface of the evaluation box 50, and bolt assembly holes 2d, 2d (see FIG. 6) provided on the other end 2c (FIG. 6) side of the terminal plate of the fuse. 6), the large current fuse 1 is placed on the table 50T while passing the bolt 51 through the bolt assembly hole 2d of the fuse terminal plate, and the evaluation box 50 and the large current fuse 1 are screwed. Put on.
Thereafter, the temperature of the evaluation box 50 is lowered from normal temperature to −30 ° C., and further raised to 100 ° C., whereby thermal shock evaluation of the large current fuse is performed.

  However, when performing a thermal shock evaluation of a large current fuse, there is a problem that an unknown cause of damage to the fuse link 5 or the transparent cover 30 sometimes occurs, and an accurate thermal shock evaluation cannot be performed.

The present applicant investigated the cause and found that it was caused by the difference between the thermal expansion coefficient of the tab-shaped terminal plates 2 and 2 of the fuse and the thermal expansion coefficient of the evaluation box 50.
That is, when thermal deformation due to heating or cooling occurs due to the difference in coefficient of thermal expansion, a dimensional change occurs with the bolt assembly holes 2d and 2d that are screwed to the evaluation box 50 as fulcrums. Then, when the dimensional change generates a compressive stress or a tensile stress in the fuse itself, and the dimensional change amount due to the thermal deformation of the evaluation box 50 exceeds the dimensional change amount due to the thermal deformation of the tab-shaped terminal plates 2 and 2 of the fuse, If the fuse link 5 or the transparent cover 30 is pulled (at the time of heating) or compressed (at the time of cooling) at the bolt assembly holes 2d, 2d, the fuse link 5 or the transparent cover 30 is damaged when the force increases. I found out.

  The large current fuse 1 is assembled by inserting screws or bolts into the bolt assembly holes 2d and 2d formed on the other end 2c side of the terminal board 2, respectively. Since it itself has irregularities due to manufacturing errors, when the tab-like terminal plates 2 and 2 are assembled with screws, bolts, etc., the large current fuse 1 is assembled in a state where deformation and stress accompanying it are generated. There was a case.

  When the fuse 1 for high current is used, especially when the fuse link 5 is blown in a state where the compressive stress generated by the assembly is applied, there is a possibility that a secondary short circuit may occur due to contact of the blown portion. It was.

  The present invention has been made to solve the above-described problems, and prevents damage to the fuse link 5 and the transparent cover 30 at the time of thermal shock evaluation, and does not cause such a problem at the time of assembly or use. An object is to provide a current fuse 1.

In order to achieve the above object, the first invention is characterized in that, in the fuse 1 for high current, a stress absorbing portion is formed between the bolt assembly hole of the tab-like terminal plate and the thick portion. .
Further, the second invention is characterized in that, in the first invention, the stress absorbing portion is provided along the thick portion in the width direction of the fuse link.
A third invention is characterized in that, in the second invention, a plurality of through holes are formed as the stress absorbing portion, and the plurality of through holes are provided in a staggered manner (fourth invention).
The through hole may be a perfect circle (fifth invention) or an ellipse having a major axis in the longitudinal direction of the fuse (sixth invention). In addition, the through hole may be replaced with a slit (seventh invention) or a thin wall. A portion (eighth invention) may be formed.

  With the above configuration, in the large current fuse having the fusible fuse link 5 installed on the opposing ends 2a, 2a of the pair of tab-shaped terminal plates 2, 2, the bolts of the tab-shaped terminal plates 2, 2 are assembled. Since the stress absorbing portion 40 that absorbs stress concentration is formed along the thick portion 11 between the through holes 2d and 2d and the thick portion 11 that reinforces the fuse link 5, the fuse is taken into account at the time of thermal shock evaluation. The tab-like terminal plates 2 and 2 and the difference in thermal expansion coefficient between the evaluation box 50 cause thermal deformation accompanying heating and cooling, and the large current fuse 1 is a screwed portion to the evaluation box 50. Even if a tensile stress or a compressive stress is generated due to a dimensional change with the bolt assembly through holes 2d and 2d as fulcrums, the stress absorbing portion 40 can absorb the deformation and prevent the fuse link 5 and the transparent cover 30 from being damaged. Do Both can be prevented the occurrence of deformation and secondary short during assembly by the stress absorbing portion 40 of the high-current fuse 1.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
<Example 1>
FIG. 1 shows a first embodiment of a large current fuse 1 according to the present invention, in a state in which a transparent cover 30 provided on a fuse link 5 portion is removed. For the large current fuse 1 according to the present invention, the same parts as those described with reference to FIG.

In FIG. 1, the stress absorbing portion 40 is provided along the thick portion 11 in the width direction between the bolt assembly holes 2 d and 2 d of the tab-like terminal plates 2 and 2 and the thick portion 11.
FIG. 2 shows an example in which a plurality of through holes 40 are provided in a staggered manner.
The plurality of through holes 40 can be integrally formed when the tab-like terminal plates 2 and 2 are formed by pressing.

  The thick part 11 becomes the reinforcing member 10 of the fuse link 5 together with the installation part 12 and has high rigidity. Compared with the thick portion 11 having rigidity, the stress absorbing portion composed of the plurality of through holes 40 can be deformed as a portion having relatively low rigidity. Even if thermal deformation due to heating or cooling occurs due to the difference between the thermal expansion coefficients of the plates 2 and 2 and the evaluation box 50, the deformation can be absorbed.

FIG. 4 shows how a plurality of through holes 40 provided in a staggered manner as stress absorbing portions absorb deformation.
When “a tensile stress is generated” of (a), the through-holes 40 (FIG. 2) provided in a staggered shape are deformed into a horizontally long elliptical shape 40 ′ by the tensile stress, thereby absorbing the stress.
In (b) “when compressive stress occurs”, the through holes 40 (FIG. 2) provided in a staggered shape are deformed into a vertically long oval shape 40 ″ by the compressive stress, thereby absorbing the stress.

<Example 2>
FIGS. 5A and 5B are plan views showing a large current fuse according to the second embodiment of the present invention. FIG. 5A is a room temperature, and FIG. 5B is a heating / expansion state.
Although the shape of the through-hole 40 (FIG. 2) of Example 1 was a perfect circle, it does not necessarily need to be a perfect circle, and Example 2 is an elliptical hole 400 having a major axis in the longitudinal direction of the fuse (FIG. 5a). It is formed with. By adopting such a shape, the elliptical hole 400 can greatly change in the longitudinal direction as shown in FIG. 5B during compressive stress, and therefore, a higher stress absorbing ability can be exhibited.

<Example 3>
As a configuration of the stress absorbing portion, instead of the through holes 40 and 400, a slit portion of a rectangular hole may be formed as the third embodiment. In the third embodiment, the rectangular hole slit can greatly change in the longitudinal direction at the time of compressive stress as compared with the second embodiment, so that a higher stress absorbing ability can be exhibited.

<Example 4>
Further, as a fourth embodiment, a thin bottomed portion may be formed instead of the through hole. In Example 4, since the current passes through the thin-walled bottom portion, the resistance value can be lowered as compared with Examples 1-3. Both have shapes that can sufficiently absorb deformation against both compressive stress and tensile stress.

  Further, the bolt assembly through-holes 2d and 2d themselves are not perfect circles, and the oval shape having the long axis in the longitudinal direction of the fuse is used to eliminate the clearance generated between the bolts of the evaluation box 50 and the second bolt. It can also be a stress absorbing part.

  By providing these stress absorbing portions 40, when the large current fuse 1 is assembled with the tab-shaped terminal plates 2 and 2 with screws, bolts, etc., deformation of the large current fuse 1 and generation of stress associated therewith are prevented. Is done.

  Further, when the fuse link 5 is blown out in a state where the compressive stress generated by the assembly is applied during use, there is a possibility that a secondary short circuit may occur due to contact of the blown part. Since the compressive stress is absorbed by the provision of 40, contact of the melted portion is prevented, and there is no possibility that a secondary short circuit occurs.

  As described above, in the large current fuse having the fusible fuse link 5 installed on the opposite ends 2a, 2a of the pair of tab-shaped terminal plates 2, 2, the bolts of the tab-shaped terminal plates 2, 2 are assembled. Since the stress absorbing portion 40 that absorbs stress concentration is formed along the thick portion 11 between the through holes 2d and 2d and the thick portion 11 that reinforces the fuse link 5, the fuse is taken into account at the time of thermal shock evaluation. The tab-like terminal plates 2 and 2 and the difference in thermal expansion coefficient between the evaluation box 50 cause thermal deformation accompanying heating and cooling, and the large current fuse 1 is a screwed portion to the evaluation box 50. Even if a tensile stress or a compressive stress is generated due to a dimensional change with the bolt assembly through holes 2d and 2d as fulcrums, the stress absorbing portion 40 can absorb the deformation and prevent the fuse link 5 and the transparent cover 30 from being damaged. Then , It is possible to prevent the occurrence of deformation and secondary short during assembly by the stress absorbing portion 40 of the high-current fuse 1.

It is a top view which shows the fuse for large currents concerning Example 1 of this invention. It is an enlarged view of the A part of FIG. It is a figure explaining the direction of the compressive stress and tensile stress which act on a fuse. It is an enlarged view of A part of Drawing 1 at the time of tensile stress (a) and compression stress (b). It is a top view which shows the fuse for large currents based on Example 2 of this invention, (a) is at the normal temperature, (b) is at the time of heating and expansion. It is a top view which shows the fuse for large currents of a prior art example. It is a figure explaining the method of thermal shock evaluation, (a) is a top view, (b) is a perspective view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Large current fuse 2 Terminal board 5 Fuse link 10 Reinforcement member 11 Thick part 12 Construction part 30 Transparent cover 40,400 Stress absorption part

Claims (8)

A fusible fuse link is installed at opposite ends of a pair of tab-shaped terminal plates, a reinforcing member comprising a resin thick portion and an installation portion is formed around the fuse link, and the fuse link is In the large current fuse in which a transparent cover is attached to the thick part so as to cover,
A fuse for large current, wherein a stress absorbing portion is formed between a bolt assembly hole of the tab-like terminal plate and the thick portion.   2. The large current fuse according to claim 1, wherein the stress absorbing portion is provided along the thick portion in a width direction of the fuse link.   3. The large current fuse according to claim 1, wherein the stress absorbing portion is formed by a plurality of through holes.   4. The large current fuse according to claim 3, wherein the plurality of through holes are provided in a staggered manner.   5. The large current fuse according to claim 3, wherein the plurality of through holes are perfect circles.   5. The large current fuse according to claim 3, wherein the plurality of through holes are oval having a major axis in a longitudinal direction of the fuse.   3. The large current fuse according to claim 1, wherein the stress absorbing portion is formed by a through slit.   3. The large current fuse according to claim 1, wherein the stress absorbing portion is formed of a thin portion.

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