JP3665654B2 - Fused fusible body used for electric wire fuses and the like and method for producing the same - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to the improvement of a fuse fusible body made of a low-melting-point alloy in which both ends thereof are directly melt-bonded between electric wire connection terminals, etc., and particularly the joint portion is fatigued due to stress concentration such as compression and tension, The present invention proposes a fuse fuser that is used in electric wire fuses (or high-pressure cutouts) that are designed to disperse the stress applied to the fuser over its entire length so as not to break the cracks.
[0002]
[Prior art]
In the low-voltage distribution line, an electric wire fuse 100 as shown in FIG. 6 is interposed in the middle of the lead-in line to the customer. The structure of the electric wire fuse 100 has a structure in which a fusing part 102 of a low melting point alloy 101, a silver wire or a copper wire 103, and electric wire connection terminals 105 of copper pipes arranged at both ends thereof are connected in series. The fuse element 100a is housed in an insulating case 106 made of synthetic resin so that a part of both the electric wire connecting terminals 105 protrudes out of the case 106, and the protruding connecting terminal 105 further protrudes. Is fixed so as not to move by an adhesive or a driving pin in the through-hole 106a of the insulating case 106. Note that the space 104 of the case 106 may be used as a space for containing an arc extinguishing agent as shown in FIG. 4 (in the case of FIG. 6, no arc extinguishing agent is used).
[0003]
Moreover, the said electric wire fuse 100 is the three of Sn (tin) -Pb (lead) -Cd (cadmium) as the soluble body 101 which comprises the fusing part 102, Sn (tin) -Pb (lead). A low melting point alloy made of the original eutectic alloy is used.
[0004]
[Technical issues to be solved]
By the way, the electric wire fuse 100 having the above structure is fixed so that the electric wire connecting terminal 105 does not move at the penetrating portion of the insulating case 106 as described above. The insulation case 106 is fixed. Therefore, when the fuse is used under direct sunlight such as midsummer and the temperature rises, the thermal expansion coefficient of the insulating case 106 made of a synthetic resin member is a fuse element made of a metal member. Since it is larger than the thermal expansion coefficient of 100a, the insulation case 106 having a large expansion coefficient applies a tensile force to the fusible body 101 due to the difference. If the temperature drops at night, the insulating case 106 applies a compressive force to the fusible body 101. That is, in the electric wire fuse 100 having the conventional structure, the compressive and tensile stress parallel to the arrow 50 direction is repeatedly applied to the fusible body 101 made of the low melting point alloy.
[0005]
Further, as shown in FIGS. 7 and 8, the above-described fusible body 101 of the electric wire fuse has a shape in which stress tends to concentrate, particularly at the joint portion 107 with the terminal 105. That is, conventionally, after a low melting point alloy (soluble body 101) is drawn to a predetermined thickness by a die, it is cut to an appropriate length to form a round column-shaped soluble body 101 shown in FIG. Since both ends of the melted body 101 are melt-bonded as shown in FIG. 7 so as to be pressed against the heated bonded portion 105 (wire connection terminal), the melted portion 101b of the fusible body 101 is enormous as shown in FIG. The outer peripheral diameter of the boundary 101d with the subsequent non-molten portion 101c is acute as shown in FIG. Therefore, when the compressive and tensile stresses are repeatedly applied, the stress is concentrated on the portion 101d, and the fusible body 101 is fatigued at an acute angle portion, and FIG. As shown in FIG. 9, a crack break occurs at the same location.
[0006]
In order to solve the above problems, the present invention does not concentrate stresses such as compression and tension on the joint between the fusible body and the terminal, but distributes it over the entire length (whole) of the fusible body. The object is to prevent cracking due to fatigue near the joint.
[0007]
[Specific means for solving the problem]
The present invention is for solving the above technical problem, that is, the problem of cracking near the fusible joint due to stress concentration,
The first invention is a low melting point alloy as shown in FIG. 1, which has a property in which both ends thereof are directly melt-bonded between wire connection terminals, and stress such as compression and tension is applied to both ends thereof. In the fuse fusible body, the outer peripheral diameter of the boundary part 4c between the melting part 4a and the non-melting part 4b located at both ends of the fusible body 4 is stressed from the end part toward the longitudinal center of the fusible body 4. The present invention proposes a fuse fusible body to be used for an electric wire fuse or the like that is formed into a smooth curve that becomes narrow for a while so that concentration does not occur, and the central portion 4d is linearly formed. .
[0008]
The second invention is a fuse fusible body made of a low melting point alloy in which both ends thereof are directly melt-bonded between electric wire connecting terminals and stresses such as compression and tension are repeatedly applied to the both ends. As shown in FIG. 3, the outer diameter of the electric wire 4 is formed into a smooth curve that becomes thin for a while so that stress concentration does not occur from the joint side 4g side at both ends toward the longitudinal center of the fusible body. The present invention proposes a soluble fuse for use in fuses and the like.
[0009]
According to a third aspect of the present invention, there is provided a fusible body manufacturing method for use in an electric wire fuse or the like formed by connecting electric wire connecting terminals to both ends of the fusible body, wherein the fusible body is determined by a current capacity. Both ends are formed with a large diameter with respect to the thickness of the central portion, and are formed into a smooth curve so as to gradually become narrower from both ends toward the central portion, and the diameter of the end portion of the wire connection terminal is The end of the fusible body is melted and softened by forming a diameter smaller than the diameters at both ends of the fusible body, raising the temperature and pressing it against the end face of the fusible body. Provided is a method for producing a fuse fuseable body for use in a wire fuse or the like in which the end of the wire connecting terminal is inserted into the end of the body so that the end of the meltable body is further expanded to a larger diameter. Is.
[0010]
【Example】
A description will be given below with reference to FIGS. 1 to 5 showing an embodiment of the present invention. 1 is an electric wire fuse showing an embodiment of the present invention. Reference numeral 2 denotes a fuse element having two elements in which a fusing part 3 and a cut-off part 10 are connected in series. Further, both ends of the silver wire or the copper wires 8 and 8a connected to the blocking portion 10 are connected to the relay conductors 5 and 7, and further, pipe-shaped electric wire connection terminals 11 and 12 are connected to these both ends. It is made up of. Reference numeral 9 denotes an arc extinguishing agent disposed around the blocking portion 10.
[0011]
In the above, the fusible body 4 that melts and joins both ends between the relay conductor 5 and the relay conductor 6 is the same as a conventional known product, for example, Sn (tin) -Pb (lead) system, eutectic point. A low melting point alloy made of a binary eutectic alloy having a temperature of 183 ° C. is used.
[0012]
In addition, as shown in FIG. 1, one of the fusible bodies 4 is formed by enlarging both ends to prevent stresses such as compression and tension from concentrating on the melt-bonded portions 4a at both ends as shown in FIG. Are formed in a substantially dumbbell shape, and the thick fused portion 4a, the slightly melted non-fused portion 4b and the boundary portion 4c are narrowed for a while from the end side toward the center of the fusible body in the longitudinal direction. By forming it in a smooth curve and forming the central portion 4d in a straight line, the stress applied to the fusible body 4 is devised so as to be distributed over its entire length.
[0013]
In addition, as shown in FIG. 3, the outer peripheral diameter of the entire length is formed into a smooth curve so as to become narrower for a while from the joint part 4g at both ends toward the longitudinal center of the fusible body. In the same manner as described above, the stress is not concentrated only on the vicinity of the joint 4g. In addition, about the process of the said meltable body 4, it selects and manufactures suitably simple processing means from means, such as swaging processing, rolling processing, caging, forging, die-casting, and is low-cost. The shape is suitable for mass production.
[0014]
In FIG. 4, reference numeral 10 denotes a blocking portion made of a copper wire 8, which is made from a wire by swaging, and is subjected to a plating treatment if necessary. In this embodiment, the narrow portion 8 a The heat storage portion 8b and the relay conductors 5 and 7 are integrally formed. Reference numerals 5, 6 and 7 are relay conductors made of copper, and the relay conductors 6 and 7 at both ends are crimped and connected to electric wire connection terminals 11 and 12 made of copper pipes.
[0015]
In addition, when joining the relay conductor as the wire connection terminal and the fusible body 4, the relay conductors 5 and 6 are heated, and after flux is applied thereto, the fusible body 4 is melted so as to lightly press the relay conductor. Join. Reference numeral 13 denotes an inner cylinder made of a heat-resistant synthetic resin such as a premix. The fuse part 2 of the fuse element 2 is separately partitioned and stored in the melt chamber 13a, and the blocking part 10 is stored in the blocking chamber 13b. Further, the relay conductor 5 located in the center connecting the fusible body 4 and the copper wire 8 is accommodated in a state of penetrating the through hole 13d of the partition wall 13c. The relay conductor 5 is supported via a lid-shaped support fitting 14 for closing the through hole 13d.
[0016]
Next, the relationship between the shape, size, and curvature of the meltable body 4 shown in FIG. 2 and the wire connection terminal 5 shown in FIG. 1 is set as follows (unit: mm). φA = 2.5-3.6φ, φB = 3.8-4.7φ, φC = 3.0-4.2φ, R = 10-15. In these relationships, it is desirable that φA <φB and φC <φB with φA and φC as a reference from the relationship of current capacity. Further, when welding the wire connection terminal 5 and the meltable body, the large diameter portion 4a of FIG. 2 melts and expands as shown in FIG. 1, but the curve of the bulging portion 4a and the inclined portion (curved portion of FIG. 2). ) It is preferable to perform welding so as to form a curve in which 4c is connected.
[0017]
Reference numeral 15 denotes an intermediate cylinder made of a synthetic resin such as polycarbonate, and a synthetic resin support lid 15a is fitted to one end of the opening. Reference numeral 16 denotes a bush, which is inserted into the outer periphery of the wire connection terminal 12 in the vicinity of the crimping portion, and is open at one end, and the molding material enters into the insulating case 17 from the portion 16a, It is devised so that no air remains in this portion. As described above, reference numeral 17 denotes an insulating case made of polycarbonate resin or the like, which tightly covers the outer peripheral surface of the intermediate cylinder 15 by injection molding. At this time, the wire connection terminals 11 and 12 are insulated. The case 17 is fixed so as not to move at the penetrating portion 17a. 18 is a sealing material made of silicone resin injected into the gap between the terminal and the insulating case, 19 is an insulating terminal cover made of rubber or resin, and 28 is a crimp-bonded connection to the wire connection terminal 12. -Shows the electrical wire.
[0018]
Note that the fuse 20 shown in FIG. 5 shows another embodiment of the present invention using the same fusible body 4 having the above-described configuration, and is applied to a tension fuse 20 for high-pressure cutout. is there. 21 is an insulation tube, 22 is an upper terminal, 23 and 24 are resistance wires (relay conductors) respectively connected to the wire connection terminals 5 and 6, 25 is a spacer made of an insulating plate, and 26 is a lead made of a stranded wire. The lead wire 27 is a terminal with a claw at the end of the lead wire, and the fuse applies stress to the fusible body 4 through the lead wire 26 and the resistance wire 23.
[0019]
【The invention's effect】
In the present invention, the shape of the outer peripheral diameter in the vicinity of the joint portion of the fusible body is made a smooth curve so that it gradually narrows from the end side toward the center in the longitudinal direction of the fusible body. Since stress such as tension is not concentrated on the joint between the fusible body and the terminal (relay conductor), but is distributed over the entire length of the fusible body (overall), the cracks due to fatigue in the vicinity of the joint as has occurred in the past Can be prevented.
[0020]
In addition, since the outer diameter of the fusible body is formed into a smooth curve over the entire length so as to become narrower for a while from the end side toward the center of the fusible body, the stress is evenly distributed over the entire length of the fusible body. A crack of cracks can be prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a joined state between a relay conductor and a fusible body.
FIG. 2 is a front view of a fusible body.
FIG. 3 is a sectional view showing an embodiment different from FIG.
FIG. 4 is a cross-sectional view of an electric wire fuse using a fusible body.
FIG. 5 is a cross-sectional view of a tension fuse using a soluble material.
FIG. 6 is a cross-sectional view showing a schematic structure of a conventional type electric wire fuse.
7A and 7B show a joined state of the fusible body used in FIG. 6, where FIG. 7A is a partial cross-sectional view showing a state before a fracture break and FIG.
FIG. 8 is an enlarged sectional view in a circle of FIG. 7 (a).
FIG. 9 is a cross-sectional view showing a state where a crack is formed at the end of the fusible body.
FIG. 10
The front view of a soluble body.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electric wire fuse 2 fuse element 4 fusible body 4a fusion | melting part 4b non-melting part 4c boundary part 4d center part 4g junction part 5 relay conductor 6 relay conductor 7 relay conductor

Claims (1)

In the manufacturing method of fusible body for use in electric wire fuses and the like formed by connecting electric wire connection terminals (5) to both ends of the fusible body (4) ,
In the meltable body ( 4 ), the thickness of the melted part (4a) positioned on both sides of the non-melted part (4b ) is increased with respect to the thickness of the non-melted part ( 4b ) determined by the current capacity. The boundary part in each of the fusion | melting part (4a) formed and located in the both sides of the said meltable body ( 4 ), and the non-melting part ( 4b ) located in the center part of the said meltable body ( 4 ) ( The curve in the longitudinal direction on the outer periphery of 4c) is formed into a smooth curve that becomes narrower for a while so that stress concentration does not occur from each melted part (4a) toward the non-melted part ( 4b ) ,
On the other hand, the diameter of the end portion of the wire connection terminal (5) is formed smaller in diameter than the diameter of the melted portion (4a) to be located on both sides of the friendly熔体(4),
In connecting the end of the wire connection terminal (5) to the melted part (4a) located on both sides of the meltable body (4),
The temperature of the end of the wire connection terminal (5) is raised and pressed against the end face of the melted part (4a) of the meltable body (4) to be positioned on both sides of the meltable body (4) . While melting and softening the end surface side of the melting portion (4a) , the end portion of the electric wire connection terminal (5) is inserted into the melting portion (4a) from the end surface side, and the longitudinal length of the outer periphery of the melting portion (4a). used for's like pigweed - - direction of the curve, the wire pigweed, wherein Rukoto inflated large diameter so as to form a curve which is continuous with the longitudinal direction of the curve at the outer circumference of the boundary portion (4c)'s fusible Manufacturing method.

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