JP2009252452A - Mounting structure of fusible link - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an excessive stress load on a fusible link which is caused by a thermal expansion rate difference when respective terminals of the fusible link are fixed with screws to a block body made of a synthetic resin. <P>SOLUTION: In a fusible link mounting structure, a pair of terminals 4 of a fusible link 3 and mating circuits 10 to 12 are fixed together to a block body 1 made of the synthetic resin with bolts 13 and nuts 9. On the block body 1, a pair of block body portions 17 and 18 housing the nuts 9 respectively are disposed to be apart from each other, and the block body portions 17 and 18 are connected together via a slender connecting wall 15, which in turn is formed into a hollow shape by a longitudinal slot 26 and is formed with a flexible portion. The block body portions 17 and 18 are thus formed as an approximately S-shaped flexible wall including the connecting wall 15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fusible link mounting structure that can reduce stress load on a fusible part caused by a difference in thermal expansion coefficient between a synthetic resin block body and a fusible link metal terminal. .

  6 to 7 show one form of a conventional fusible link mounting structure (see Patent Document 1).

  In this structure, a synthetic resin upper case 61 and a lower case (not shown) constitute a junction box main body, and a peripheral wall 62 as a fusible link housing portion is erected on the upper case 61, and the upper case 61 and the lower case The bus bar wiring board 63 (FIG. 7) is horizontally arranged between the two, a fusible link is arranged in the peripheral wall 62, a pair of conductive metal terminals 65 of the fusible link 64, and a pair of the bus bar wiring board 63. Each of the terminals 65 and each bus bar 66 is connected and fixed by passing a bolt 68 through each hole of the conductive metal bus bar 66 and the synthetic resin insulating plate 67 and tightening with a nut 69. .

One (upstream side) bus bar 66 is connector-connected to the electric wire (not shown) from the battery, and the other (downstream side) bus bar 66 is connected to the electric wire from the alternator and a load side circuit (not shown). (See Patent Document 2). The conventional example of Patent Document 2 describes that a fusible link is connected to a terminal with an electric wire, the electric wire is connected to a bus bar in a connection box body, and the bus bar is connected to each load.
Japanese Patent Laying-Open No. 2005-210881 (FIGS. 1 and 5) JP-A-10-174254 (FIGS. 1 and 7)

  In the electrical junction box, the junction box main body is composed of the upper case 61 and the lower case. For example, the junction box main body is composed of an integral body such as a fuse block main body, and each bus bar on the block main body side has a fusible link. When the terminals are tightened and connected with bolts and nuts, the thermal expansion coefficient of the block body made of synthetic resin is much larger than that of the fusible link conductive metal terminals and bus bars. For example, when an electrical junction box is placed in the engine room, or when the junction box body becomes hot due to the temperature of a fuse or a relay in the electrical junction box, the pair of terminals of the fusible link are caused by expansion of the block body. Being pulled strongly in the reverse direction (180 ° direction), excessive stress is applied to the fusible part (fuse body) between the pair of terminals, or in the worst case, it may be cut off. There was a concern that.

  In view of the above-described points, the present invention is an excessively large fusible link due to a difference in thermal expansion coefficient even when each terminal of the fusible link is screwed and fixed to a block body integrally formed of synthetic resin. An object of the present invention is to provide a fusible link mounting structure capable of preventing stress load.

  In order to achieve the above object, a fusible link mounting structure according to claim 1 of the present invention is a fusible link in which a pair of fusible link terminals are fixed together with a mating circuit to a synthetic resin block body with bolts and nuts. In the bull link mounting structure, a pair of block main body portions for accommodating each nut are separately disposed on the block main body, and the pair of block main body portions are integrally connected by an elongated connecting wall. .

  With the above configuration, when the block body expands greatly together with the connecting wall due to outside air or internal temperature rise, the connecting wall has a small cross-sectional area and low rigidity. Then, the strength of pulling the fusible part in the cutting direction is weakened, and an excessive stress load on the fusible part is prevented. Similarly, fatigue of the soluble part due to repeated expansion and contraction of the block body is also prevented. The connecting wall is necessary to improve the positional accuracy of the pair of block main body parts. If there is no connecting wall, the pair of block main body parts will be displaced due to warpage after resin molding, etc., and the nut housed in the block main body part In addition, the positional accuracy of the bus bar or the like which is a counterpart circuit is lowered. The tensile strength of the connecting wall is set lower than the tensile strength of the soluble part.

  A fusible link mounting structure according to a second aspect is characterized in that, in the fusible link mounting structure according to the first aspect, the connecting wall is formed hollow with a longitudinal groove portion.

  With the above configuration, the cross-sectional area of the connecting wall is further reduced, the tensile strength is weakened, and the tensile load of the fusible link during thermal expansion is further reduced. On the contrary, the bending strength and torsional strength of the connecting wall are increased to some extent by the groove, and the positional accuracy of both block main body portions is improved.

  The fusible link mounting structure according to claim 3 is the fusible link mounting structure according to claim 1 or 2, wherein a flexible portion is formed on the connecting wall.

  With the above configuration, when the block body thermally expands and a tensile force in the cutting direction acts on the fusible part of the fusible link, the flexible part of the connecting wall flexes flexibly in the extension direction and absorbs this tensile force. To do. The flexible portion may be formed on a part of the connecting wall in the longitudinal direction or may be formed entirely. The shape of the flexible portion can be set to various shapes that are easy to resin-mold, such as a substantially S-shape or a rectangular shape.

  The fusible link mounting structure according to claim 4 is the fusible link mounting structure according to claim 1 or 2, wherein the pair of block main body portions includes a substantially S-shaped flexible wall including the connecting wall. It is characterized by making.

  With the above configuration, when the pair of block main body portions expands and contracts, it is possible to flexibly flex not only in the longitudinal direction of the connecting wall but also in the longitudinal orthogonal direction (width direction of the connecting wall). The stress in not only the longitudinal direction of the fusible part) but also in the longitudinal orthogonal direction (the thickness direction of the fusible part) is absorbed and relaxed, and the fusing reliability of the fusible part is increased.

  According to the first aspect of the present invention, even if the thermal expansion coefficients of the synthetic resin block main body and the fusible link metal fusible part are greatly different, the elongated connecting wall is formed of the fusible part during thermal expansion. The tensile force is weakened to relieve the stress at the fusible part, and the stress at the fusible part is also eased in the repeated expansion and contraction. Increases reliability of fusing.

  According to the second aspect of the present invention, the cross-sectional area of the connecting wall is reduced by the groove, and the connecting wall further weakens the tensile force of the soluble part and further relaxes the stress of the soluble part at the time of thermal expansion. Since the stress of the soluble part is further relaxed in the same manner, the effect of the invention of claim 1 is promoted.

  According to invention of Claim 3, since the flexible part of a connection wall absorbs the tensile force of the cutting direction of a fusible link actively, the stress of the soluble part at the time of thermal expansion / contraction of a block main body is ensured. The effect of the invention of claim 1 is promoted by being relaxed.

  According to the invention of claim 4, by the flexible wall of the block body, stresses such as bending and torsion are relaxed in addition to the tension of the fusible link, and the quality characteristics of the fusible part are more stably secured, Reliability of fusing of fusible links is further increased.

  1 to 5 show an embodiment of a fusible link mounting structure according to the present invention.

  As shown in FIGS. 1 and 2, this structure is provided with a horizontally-long rectangular opening 6 that accommodates the fusible link 3 in the vertical wall portion 2 of the synthetic resin fuse block body 1, and on the left and right inner sides of the opening 6. A pair of nut accommodating portions 7 and 8 (FIG. 4) as fusible link fixing portions are arranged separately (separated), and each nut accommodating portion 7 and 8 accommodates a metal nut 9 and a fuse block. The main body 1 accommodates each conductive metal bus bar (mating circuit) 10-12, and a pair of left and right conductive metal terminals 4 of the fusible link 3 and each bus bar 10-12 are connected to a metal bolt 13; The fuse block 14 is tightened and connected with a nut 9.

  And the nut accommodating part 7 and 8 (FIG. 4) isolate | separated into the right and left of the opening 6 side is connected by connecting the lower end side of the opening 6 of the fuse block main body 1 with the elongate wall part (connection wall) 15 in the horizontal direction. Reinforcing the block main body portions 17 and 18, while reducing the rigidity of the connecting wall 15, the tensile force in the longitudinal direction (lateral direction) of the fusible link generated at the time of thermal expansion of the block main body portions 17 and 18 is increased. It is reduced below the cutting load of the fusible part (not shown) to prevent the fusible part from being cut due to the difference in thermal expansion coefficient between the block main body 1 and the link terminal 4.

  That is, since the nut accommodating portions 7 and 8 are separated, the tensile force to the fusible link 3 due to the thermal expansion of the fuse block body 1 is reduced. However, the strength of the fuse block body 1 is reduced by the separated nut accommodating portions 7 and 8. In order to reinforce this, the connecting wall 15 is provided. In order to reduce the tensile force generated in the fusible link 3 due to the thermal expansion of the fuse block main body 1, the connecting wall 15 is thinned and the connecting wall 15 is expanded. Less. Furthermore, as will be described later, the fuse block main body portions 17 and 18 including the connecting wall 15 are formed in an approximately S shape to absorb the expansion of the fuse block main body 1.

  The tensile strength of the connecting wall 15 is set smaller than the tensile (cutting) strength of the soluble part. The fusible part is formed continuously and integrally with the pair of flat terminals 4 and is substantially thinner than the width of the terminals 4 in a substantially straight line. The pair of terminals 4 are fixed to the case portion 5 made of insulating resin by insert molding or the like.

  As an example, the rating of the fusible link 3 is about 125A, 58V. Each terminal 4 is provided with a circular hole 4a for inserting a bolt. The bolt 13 has a washer 13b on the side of the head 13a, and the nut 9 has a rectangular flange 9a for preventing rotation on the side opposite to the head 13a. Bolt 2 is screwed with a + screwdriver.

  3 is an enlarged view of the main part of FIG. 2, and FIGS. 4 and 5 are bottom views of FIG. 3 as viewed from below.

  As shown in FIG. 3, the fusible link 3 is accommodated in the rectangular opening 6 of the block body 1 in a horizontally long manner, and the central case portion 5 is a space 16 between the block body portions 17, 18 separated left and right. In the state where the terminal 4 is in contact with the surface of each bus bar 10-12 along the left and right block body portions 17 and 18, Tightened and fixed.

  4 and 5, each nut 9 is inserted and arranged from below into the vertical groove 20 of the left and right block main body portions 17 and 18, and the groove 20 is a notch on the front side that accommodates the nut main body 9b (FIG. 1). It consists of an opening 20a and a wide guide 20b that accommodates the flange 9a (FIG. 1), and is surrounded by a pair of left and right vertical walls 21 and a rear vertical wall 22. .

  The elongated connecting wall 15 is located opposite the left and right wall portions 21 forming one groove portion 20 with a gap 23 therebetween, and the left (inner) wall portion 21 forming the other groove portion 20 extends forward. Then, the wide base portion 15b of the connecting wall 15 is integrally connected to the extended wall portion 21a. The connecting wall 15 is formed in a substantially L shape with a wide base portion 15b and a narrow elongated portion 15a. The wide base portion (base wall) 15 b can also be viewed as a part of the block main body portion 18.

  The distal end 15c of the connecting wall 15 continues integrally and perpendicularly to the side wall 24a of the connector housing 24 of the left block main body portion 17. A mating connector 25 is fitted and connected to the connector housing 24 (the lead wire from the mating connector 25 is not shown). A groove portion 26 in the longitudinal direction is formed on the lower surface side of the connecting wall 15, and in particular, the elongated portion 15 a is hollowed by the groove portion 26 to reduce the volume, and the flexibility of the elongated portion 15 a against thermal expansion and contraction (tensile compression) in the longitudinal direction is reduced. (Strength) and the strength against bending and twisting in the front-rear and up-down directions are enhanced.

  Two bus bars 10, 11 are in contact with each other and the nut 9 engaged with one groove 20, and one bus bar 12 is in contact with the nut 9 engaged with the other groove 20. The front bus bar 11 of the two bus bars 10 and 11 is the lower left long bus bar in FIG. 1, the rear bus bar 10 is the upper short bus bar in FIG. 1, and one bus bar 12 is It is a long bus bar on the lower right in FIG. Bolt insertion holes 27 are provided in the vertical plate portions 10a to 12a at the ends of the bus bars 10 to 12, respectively.

  In FIG. 1, the lower right bus bar 12 has two vertical side plates 12b facing each other via a lower connecting plate 12c, and the side plates 11b, 12b of the lower left and right bus bars 11, 12 are used for fuse connection. A pin terminal 28 and a tab terminal 29 for connector connection are formed upward. The clamping terminal 28 and the tab terminal 29 are connected to the load side through other fuses (not shown).

  A tab terminal 12d for connecting a power source from the battery is provided upward on the plate portion 12a at the front end of the lower right bus bar 12. The tab terminal 12d is accommodated in the connector housing 30 on the upper side of the right block main body portion 18. The connector housing 30 is connected to a connector-connected electric wire with a terminal (not shown) from above. An electric wire (not shown) for connecting an alternator or a converter is connected to the upper bus bar 10 by bolts 31 and nuts 32 together. The upper bus bar 10 is inserted into the vertical groove 33 of the left block main body portion 17 from above.

  4 and 5, the left front bus bar 11 has a side plate portion 11b bent rearward from the front end plate portion 11a and passes through a substantially vertical groove 34 in the center of the block body 1, and the right bus bar 12 is The side plate portion 12b is bent rearward from the front end plate portion 12a and is accommodated and disposed through the vertical groove 35 on the right end side of the block body 1 respectively.

  In the left block main body portion 17, the wall portions 21 and 22 of the nut receiving groove 20, the housing wall 24 a, and the narrow width portion 15 a of the connecting wall 15 are integrally continuous while being bent in a substantially U shape in plan view. In the block main body portion 18, the wall portions 21, 22 of the nut receiving groove 20, the front extension wall 21 a, and the wide base portion (base wall) 15 b of the connecting wall 15 are integrally bent while being bent in a substantially L shape or a U shape. It is continuous.

  That is, the wall portions 21 and 22 of the nut receiving groove 20 of the left block main body portion 17, the housing wall 24 a, the narrow width portion 15 a of the connecting wall 15, the wall portion 21 of the nut receiving groove 20 of the right block main body portion 18, 22, the front extension wall 21 a, and the wide base portion 15 b of the connecting wall 15 constitute a substantially S-shaped or substantially crank-shaped flexible wall (flexible portion). The flexible wall has a property of being elastically restored by releasing the load after being bent.

  The rigidity of the block body 1 is lowered by the flexible walls (21, 21a, 22, 15), and the flexible wall flexes flexibly in the left and right (width) direction of the block body 1 when the block body 1 is thermally expanded and contracted. Thus, coupled with the expansion and contraction of the elongated connecting wall 15, the expansion and contraction of the block main body 1 is smoothly absorbed, and in particular, the fusible link 3 (FIG. 1) against the tensile force of the block main body 1 during thermal expansion. The strength of the soluble part is overcome and the cutting of the soluble part is reliably prevented. In addition, a decrease in fatigue strength of the soluble portion due to repeated expansion and contraction is prevented, the quality of the soluble portion is maintained equal to the initial state, and the reliability of fusing is increased.

  4 and 5, in order to make the characteristics of the flexible wall more prominent, the wide base portion 15b of the connecting wall 15 is formed to be narrow and the connecting wall 15 is configured only by the narrow portion 15a. It is also effective to provide a slit (not shown) in the front-rear direction in the wide base portion 15b to connect the right groove walls 21, 21a and the base portion 15b within a narrow range. It is also effective to form a flexible portion in the connecting wall 15 by bending a part or the whole of the elongated connecting wall 15 into a substantially S-shape to form a flexible portion (elastic portion).

  In FIG. 2, a fusible link 36, a blade-type fuse 37, an electronic board unit 38, and the like are mounted on the upper side of the block body 1 to constitute the fuse block 14. The fuse block 14 is mounted in a synthetic resin frame (not shown), and upper and lower covers (not shown) are attached to the frame to constitute an electrical connection box (not shown) as a whole. Only the fuse block 14 may be referred to as an electrical junction box.

It is a disassembled perspective view which shows one Embodiment of the attachment structure of the fusible link which concerns on this invention. It is a whole perspective view which similarly shows the attachment state of a fusible link. It is a principal part perspective view which shows the attachment state of a fusible link. It is the perspective view which looked at the attachment structure of the fusible link from the lower side. It is the top view which similarly looked at the attachment structure of the fusible link from the lower side. It is a disassembled perspective view which shows one form of the attachment structure of the conventional fusible link. It is a longitudinal cross-sectional view which similarly shows the attachment structure of the conventional fusible link.

Explanation of symbols

1 Block body 3 Fusible link 4 Terminal 9 Nut 10-12 Bus bar (mating circuit)
13 Bolt 15 Connecting wall 17, 18 Block body part 26 Groove part

Claims (4)

  In a fusible link mounting structure in which a pair of fusible link terminals are fixed to a block body made of synthetic resin with bolts and nuts together with a mating circuit, a pair of block body parts for accommodating each nut are separated from the block body. A fusible link mounting structure, wherein the pair of block main body portions are integrally connected by an elongated connecting wall.   The fusible link mounting structure according to claim 1, wherein the connecting wall is formed hollow with a longitudinal groove portion.   The fusible link mounting structure according to claim 1, wherein a flexible portion is formed on the connecting wall.   The fusible link mounting structure according to claim 1 or 2, wherein the pair of block main body portions includes a substantially S-shaped flexible wall including the connecting wall.

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