JP3722896B2 - fuse - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuse with improved fusing characteristics.
[0002]
[Prior art]
The fuse protects the electric circuit by cutting off the current when the current exceeding the specified value flows, so that the metal fusing part is blown by Joule heat generation.
[0003]
FIG. 6 shows a perspective view of an example of a conventional fuse (fusible link), and FIG. 7 shows a developed view thereof. The fuse 1 is formed by bending a single metal plate. A part of the cross-sectional area of the fusible part 2 formed to be thin is further cut into a linear body, and the part is used as a fusing part 3. .
[0004]
[Problems to be solved by the invention]
By the way, in the conventional fuse 1, since the fusing part 3 is comprised by one linear body, heat dissipation is too good, and in the case of the heat_generation | fever by the electric current (low current) slightly larger than an allowable value, The time for the fusing part 3 to reach the melting temperature becomes longer, and there is a possibility that a prompt circuit protection function cannot be exhibited. Also, when a pulse current flows due to a slice short, etc., the difference between the amount of heat generated when ON and the amount of heat released when OFF is small, so the temperature rise at the fusing part is slowed down, and the time until fusing is extended, resulting in a quick circuit. There was a possibility that the protective function could not be demonstrated.
[0005]
In consideration of the above circumstances, the present invention provides a fuse capable of quickly fusing and protecting a circuit even in the case of a low current slightly exceeding an allowable value or a pulse current caused by a slice short or the like. The purpose is to do.
[0006]
[Means for Solving the Problems]
The fuse according to the first aspect of the present invention has a fusing part formed by concentrating a plurality of wires formed by coating thin conductors with a thin insulating sheath, and provided with terminal parts at both ends of the fusing part. It is characterized by.
[0007]
Since this fuse consists of a bundle of strands whose fusing parts are insulated from each other, when the fusing part's wires generate heat due to low current and pulse current, the central part's strands influence the heat dissipation of surrounding strands. Receive. For this reason, even if the temperature of the strand at the outer periphery decreases, the temperature of the central portion continues to rise, and the strand starts to melt from the central portion of the bundle. Then, the value of the current flowing through the outer peripheral strand increases due to the melting of the central strand, and finally all the strands are melted to cut off the current.
[0008]
According to a second aspect of the present invention, there is provided a fuse according to the first aspect, wherein the thin wire is disposed between the thin conductive wire and the thin insulation sheath as a wire disposed in a central portion of the bundle of the wire. A two-layer structure wire formed by forming a low melting point metal layer having a lower melting point is used.
[0009]
In the two-layer structure wire, the outer low-melting-point metal layer is first dissolved during heat generation, and the dissolved metal diffuses into the inside of the small-diameter conductor, thereby bringing about the melting point lowering effect of the small-diameter conductor itself. Therefore, the strand at the center of the bundle constituting the fusing part is surely blown out early at a low temperature.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0011]
FIG. 1 is a perspective view showing the overall configuration of the fuse 10. The fuse 10 is configured by fusing a large number of strands 12 to form a fusing portion 14. Terminal portions 15 and 15 are provided at both ends of a bundle of strands 12. Each strand 12 is made conductive. As shown in FIGS. 3 (a) and 3 (b), the element wire 12 is formed by coating a thin wire 21 having a thickness of several tens of μm with a thin insulating sheath 22 made of resin such as enamel and having a thickness of several μm. In the fusing part 14, the wires 12 are insulated from each other by a thin insulating sheath 22.
[0012]
In this case, as the strands arranged at the center of the bundle of strands 12, as shown in FIG. 3 (b), between the narrow conductor 21 and the thin insulating sheath 22, as compared with the narrow conductor 21. A special type of wire 12B having a two-layer structure formed by forming a low melting point metal layer 23 made of low melting point tin or lead is used. Further, as the strands of the outer peripheral portion of the bundle of strands 12, a normal type strand 12 </ b> A in which the thin conducting wire 21 is directly covered with the thin insulating sheath 22 as shown in FIG. 3A is used. .
[0013]
Next, the operation will be described.
[0014]
In the fuse 10, the fusing part 14 is composed of a bundle of strands 12 insulated from each other. Therefore, when the strand 12 of the fusing part 14 generates heat due to a low current close to an allowable value, The wire 12 is affected by the heat radiation of the outer strand 12. For this reason, even if the temperature of the strand 12 of an outer peripheral part falls, the strand 12 of a center part continues a temperature rise, and the strand 12 starts fusing from the center part of a bundle | flux. Then, the value of the current flowing through the outer peripheral strand 12 is increased by the melting of the strand 12 at the center, and finally all the strands 12 are fused to cut off the current.
[0015]
In this case, since the strand at the center of the bundle is the strand 12B having the two-layer structure shown in FIG. 3B, the outer low-melting-point metal layer 23 is first melted during heat generation, and the melted metal Is diffused into the inside of the thin conducting wire 21, thereby bringing about a melting point lowering action of the thin conducting wire 21 itself. Therefore, the strand 12B in the central portion is surely blown out early at a low temperature, and as a result, the entire blown portion 14 is blown out quickly.
[0016]
Further, when a pulse current flows due to a slice short or the like, a current waveform as shown in FIG. Accordingly, as shown in FIG. 5A, in the conventional fuse, the balance of the balance is achieved by the heat generation when the pulse wave current is ON and the heat dissipation when the pulse wave current is OFF, so that the temperature rise is slow. In the fuse, even when the pulse wave current is OFF, the temperature of the wire 12 at the center of the bundle rises due to the heat radiation of the wire 12 at the outer periphery, so that the temperature rises reliably without receiving a large heat loss Fusing.
[0017]
FIG. 4 shows the result of the fusing characteristics obtained by experimenting with a certain sample. This figure shows that when a standing wave current is passed through the fuse of the present invention, when a pulse wave current is passed through the fuse of the present invention, and when a standing wave current is passed through the conventional fuse, the energization current and the time until fusing Shows the relationship of time.
[0018]
From this figure, the fuse of the present invention is surely blown at a lower energizing current value than the conventional fuse, and when comparing the time to blow with the same fusing current, the fuse of the present invention is better than the conventional one. It can be seen that the time is short. In particular, in the case of a pulse wave current, there are cases where the conventional fuse is difficult to blow, but in the case of the fuse of the present invention, it is well approximated to the case of a standing wave current, and it can be seen that even a low current value is surely blown in a short time.
[0019]
As a result, according to the fuse of the present invention, circuit protection can be achieved by fusing reliably and promptly both in the case of a low current close to an allowable value and in the case of a pulse current.
[0020]
In the above-described embodiment, the double strand 12B is used at the center of the strand, but this is not always necessary, and the same strand 12A may be disposed at the center and the outer periphery. Good.
[0021]
【The invention's effect】
As described above, according to the invention of claim 1, the fusing part is formed of a bundle of a plurality of strands. Therefore, even when a slice short or a short of a low current value close to an allowable current is achieved, the fuse is quicker and faster. A reliable current interruption can be performed. Moreover, a wide range of allowable current values can be easily realized by changing the thickness and the number of the strands of the fusing part.
[0022]
According to the invention of claim 2, in addition to the effect of the invention of claim 1, the wire at the center of the bundle is surely blown early, so that the overall fusing speed is increased and the circuit protection function is more agile. Can be fulfilled.
[Brief description of the drawings]
FIG. 1 is a perspective view of a fuse as an embodiment of the present invention.
2 is a perspective view showing a state in which the fuse of FIG. 1 is cut at a fusing part. FIG.
3 shows the structure of a wire used for the fusing part of the fuse of FIG. 1, (a) is a partial perspective view showing the structure of a wire 12A disposed on the outer periphery of the bundle, and (b) is the center of the bundle. It is a fragmentary perspective view which shows the structure of the strand 12B arrange | positioned at a part.
FIG. 4 is a diagram comparing the fusing characteristics of a fuse of the present invention and a conventional fuse.
FIG. 5A is a diagram showing a comparison of the temperature rise characteristics of a blown part at the time of a pulse current between the fuse of the present invention and a conventional fuse, and FIG. 5B is a diagram showing a pulse current waveform due to a slice short or the like.
FIG. 6 is a perspective view showing an example of a conventional fuse.
7 is a development view of the fuse of FIG. 6. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Fuse 12 Strand 12A Strand 12B of outer periphery of bundle 12B Strand 14 of bundle | flux center part 14 Fusing part 21 Thin diameter lead wire 22 Thin insulation sheath 23 Low melting point metal layer

Claims (2)

A fuse comprising a fusing part formed by concentrating a plurality of strands formed by coating thin conductors with a thin insulating sheath, and terminal parts are provided at both ends of the fusing part. The fuse of claim 1,
An element having a two-layer structure in which a low-melting-point metal layer having a lower melting point than that of the thin-diameter conductor is formed between the thin-diameter conductor and the thin insulating sheath as the element arranged in the center of the bundle of the strands. Fuses characterized by using wires.

Images