JPS5935136B2 - temperature fuse - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature fuse that has the function of cutting off a conductive path when heated above a certain level.

FIG. 1 shows a conventional temperature fuse.

In FIG. 1, the temperature heat, which is indicated by the reference numeral 1 as a whole, is connected to a first
conductive wire 2 and second conductive wire 3, one end of which is fitted to the first conductive wire 2 and electrically connected to the first conductive wire 2, while the other end is fitted to the second conductive wire 3. A metal case 5 is electrically isolated from the second conductor 3 by an insulator 4.
and a fusible pellet 6, a hold spring 7, a disk 8, three conductive balls 9, and a bush spring 10 arranged between the first conductor 2 and the second conductor 3 in the metal case 5. It is composed of.

The temperature-sensitive pellet 6 is made of a suitable organic compound and melts when a predetermined temperature is reached.

The tip of the second conducting wire 3 is fitted between and in contact with the three balls 9.

That is, a conductive path is formed between the first conductive wire 2 and the second conductive wire 3 via the metal case 5 and the three balls 9.

The configuration shown in FIG. 1 is in a state before the predetermined temperature is reached, but when the predetermined temperature is reached, the soluble pellet 6 melts, the hold spring 7 changes from the compressed state to the expanded state, and the 3
The individual balls 9 cannot be strongly suppressed.

Therefore, the bushing spring 10 pressing the three balls 9 on the opposite side operates to separate the three balls 9 from the tip of the second conducting wire 3, thereby interrupting the conductive path.

The conventional temperature fuse described above has the following drawbacks.

That is, if the three balls 9 are arranged at symmetrical positions with the second conductor 3 as the center, the above operation is performed, but if they are arranged even slightly deviated, an abnormality occurs, that is, the melting occurs. When the pellet 6 melts, the ball 9 may not move smoothly and the conductive path may not be interrupted.

Therefore, when assembling the above structure, it is necessary to always set the three balls 9 at predetermined positions, but in practice this is a rather troublesome and complicated work.

Furthermore, since the temperature fuse has a spherical contact portion in the conductive path, it has a large electrical resistance and is easily overheated.

Furthermore, although it has been considered to use a disk instead of the three balls, it is difficult to obtain good electrical contact between the outer peripheral surface of the disk and the metal case.

In other words, if the outer diameter of the disc is increased in order to improve the contact condition, there is a risk that it will not operate smoothly in the event of an abnormality.

The present invention was made in order to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a temperature fuse that can operate reliably and is electrically stable.

In the present invention, a movable conductive plate is used in place of the three balls described above, and a tapered hole is provided in the center of this movable conductive plate, and slits are provided in at least three places around the tapered hole, one of which is provided with a tapered hole in the center. The above object is achieved by having a structure in which slits are cut in several places.

The present invention will be described below with reference to illustrated embodiments.

2 to 4 show one embodiment of the present invention.

In these figures, 15 is a cylindrical case made of a metal with good electrical conductivity and good thermal conductivity, such as copper.

A first conducting wire 16 is caulked and fixed to one end of this case 15, and a second conducting wire 17 is electrically insulated and connected to the case 15 at the other end via an insulator 18 such as ceramic. ing.

The first conducting wire 16 and the second conducting wire 17 inside the case 15
Between the soluble pellet 19 and the hold spring 20
, a movable conductive plate 21, and a bushing spring 22 are arranged in this order.

The soluble pellets 19 are made of a suitable organic compound and melt at a temperature above a certain level.

The movable conductive plate 21 is made of a disk having spring properties, such as phosphor bronze.

A hold spring 20 and a bushing spring 22 arranged on both sides connect the movable conductive plate 21 to the second conductive wire 1.
It is biased so as to maintain the state in which it is brought into contact with the distal end portion 17a of No.7.

Reference numeral 23 denotes an insulating sealing body made of epoxy resin or the like and adhered to the end face of the insulator 18.

The tip end 17a of the second conducting wire 17 is formed into a conical shape, and the tip end 17a is placed in the center of the movable conductive plate 21 relative to the conical shape.
A tapered hole 24 is provided which substantially matches the diameter 7a.

Furthermore, slits 25a and 25b are provided at three locations around the tapered hole 24 of the movable conductive plate 21.

25C are provided radially, and one slit 25c is cut at the outer edge.

Note that it is sufficient that the slits be provided in at least three locations, and the number of locations may be increased.

In addition, the inner edge 2 of the uncut slits 25a and 25b
6a and 26b are formed into circular shapes.

The outer peripheral edge 27 of the movable conductive plate 21 on the soluble pellet side is chamfered to form an arcuate surface.

Furthermore, the movable conductive plate 21 expands in the radial direction when the tip end 17a of the second conductive wire is press-fitted into the tapered hole 24.
Its outer peripheral surface is pressed against the inner wall of the case 15.

In the above configuration, since the soluble pellet 19 is solid as shown in FIG. 2 at room temperature, the first conducting wire 16
A constant distance is maintained between the movable conductive plate 21 and the movable conductive plate 21, and a conductive path is formed through the case 15.

When the fusible pellet 19 melts due to an abnormal temperature rise, the force of the bushing spring 22 exceeds the force of the hold spring 20, and the movable conductive plate 21 moves to the left in FIG. 17, and the conductive path is cut off.

In the temperature fuse according to the present invention, the tip of the second conductive wire is conical, a tapered hole is provided in the center of the movable conductive plate, and slits are provided radially at at least three locations around the tapered hole. At the same time, by cutting a slit in one of the slits on the outer edge, the movable conductive plate has spring properties and easily expands and deforms in the radial direction, and its outer peripheral surface is pressed against the inner wall of the case. Since the leading end of the conductor and the movable conductive plate form a connection with a large contact area between the conical surface and the tapered surface, electrical resistance is low at room temperature, and an electrically stable contact state is maintained.

Further, since the movable conductive plate is largely deformed in the radial direction, the outer peripheral surface quickly separates from the inner wall of the case when the soluble pellet is melted, thereby reliably blocking the conductive path.

Note that by forming the inner edge of the unopened slit into a circular shape, the effect of smoother expansion and deformation of the movable conductive plate in the radial direction can be obtained.

In particular, the larger the circular diameter of the inner edge, the more the pressing force at the tip of the second conductive wire can be reduced.

This is because, as a result of experiments, it has been confirmed that when the diameter is doubled, the pressing force is reduced by almost half even though the movable conductive plate is expanded and deformed to the same extent.

In addition, by chamfering the outer periphery of the movable conductive plate on the soluble pellet side to form an arc surface, even if the movable conductive plate is slightly bent due to the pressing force of the second conductive wire, the outer periphery of the movable conductive plate will remain on the inner wall of the case. can slide smoothly along the

Further, according to the present invention, since the movable conductive plate has a simple structure, assembly is easy, and assembly can be automated.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional temperature fuse, FIG. 2 is a sectional view showing an embodiment of the temperature fuse according to the present invention, and FIG.
The figure is a front view showing the movable conductive plate used in the same example.
The figure is a sectional view taken along line IV-N in FIG. 3. In the figure, 15 is a case, 16 is a first conducting wire, 17 is a second conducting wire, 18 is an insulator, 19 is a soluble pellet, 21 is a movable conductive plate, 24 is a tapered hole, and 25a. 25b and 25c are slits.

Claims (1)

[Claims] 1. A conductive cylindrical case, a first conductive wire conductively coupled to one end of the case, and an electrically insulated wire electrically connected to the case via an insulator at the other end of the case. The second conducting wire is connected in a state between the first conducting wire and the second conducting wire, and is arranged so that the center portion is in contact with the tip of the second conducting wire and the outer peripheral surface is in contact with the inner wall of the case. a movable conductive plate, a soluble pellet disposed between the movable conductive plate and the first conductive wire, and a hold spring disposed to press a surface of the movable conductive plate facing the soluble pellet; In a temperature fuse equipped with a bushing spring arranged to press a surface of the movable conductive plate facing the second conductive wire, the tip of the second conductor in contact with the center of the movable conductive plate has a conical shape, In contrast, a tapered hole is provided in the center of the movable conductive plate that almost matches the tip, and slits are provided radially in at least three locations around this tapered hole, and one of
A temperature fuse characterized by having several slits cut into the outer edge. 2. The temperature fuse according to claim 1, wherein the inner edge of the unopened slit is formed into a circular shape. 3. The temperature fuse according to claim 1 or 2, wherein the outer peripheral edge of the movable conductive plate on the fusible pellet side is chamfered to form an arcuate surface.