JPH10177833A - Temperature fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make structure simple, reduce production cost, and make handling easy. SOLUTION: A temperature fuse has a glass tube 1, caps 2, 2, terminals 3, 4 connected to the caps 2, 2 respectively, a conductor 5 capable of moving from an electricity passing position coming in contact with the terminals 3, 4 from the inside in the diameter direction of the glass tube 1 to the breaking position separating from the terminal 4, a temperature sensitive pellet 6 which is arranged on one side of the conductor 5, obstructs move to the breaking position of the conductor 5 in the state before melting, melts by temperature rising to the rated temperature, and allows it to move to the breaking position of the conductor 5, a coil spring 7 which is arranged on the other side of the conductor 5, holds the conductor 5 by pressing against the temperature sensitive pellet 6, and when the temperature sensitive pellet 6 is melted, moves the conductor 5 to the breaking position, and an insulator 8 which insulates the coil spring 7 from the conductor 5. The glass tube 1 is transparent. The conductor 5 and the insulator 8 are spherical.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal fuse. More particularly, the present invention relates to a thermal fuse that opens a circuit by melting a temperature-sensitive pellet due to an increase in temperature.

[0002]

2. Description of the Related Art A temperature-sensitive pellet that melts at a rated temperature as a fuse that cuts off current when the ambient temperature reaches a temperature (referred to as a rated temperature in this specification) previously determined by various standards or design conditions. Conventionally, there is a thermal fuse that uses a thermal fuse. In a conventional thermal fuse using this thermosensitive pellet, for example, as shown in FIG. 7, a lead wire 102 and a star-shaped contact 103 are contacted by a compressed spring 101, and the lead wire 102 → star-shaped contact 103 →
Electric current flows from the metal case 104 to the lead wire 105. Discs 106 are arranged at both ends of the spring 101 to protect the star-shaped contact 103 and the thermosensitive pellet 107 from the spring 101.

When the rated temperature is reached during energization of the thermal fuse, the thermosensitive pellet 107 melts and loses its shape.
For this reason, the spring 101 is extended, and the star-shaped contact 103 is pushed toward the thermosensitive pellet side by the spring force of the spring 108 interposed between the star-shaped contact 103 and the porcelain insulator 109, and the lead wire 102 and the star-shaped contact 103 And cut off the current. In this state, the metal case 104 and the spring 108 are insulated from the lead wire 102 by the porcelain insulator 109 and the sealing resin 110.

[0004]

However, in the above-described thermal fuse, two springs 101 and 108 are disposed on both sides of the star-shaped contact 103, and the temperature-sensitive pellet 107 and the star-shaped contact 103 are protected. For this purpose, two discs 106 are provided, and furthermore, a porcelain insulator 109 and a sealing resin 110 are required to insulate the lead wires 102, so that the number of parts is increased and the production is troublesome. Cost was high.

Further, the state inside the metal case 104 cannot be observed from the outside, and the melting of the thermal fuse cannot be visually confirmed. For this reason, in order to confirm the fusing of the fuse, it was necessary to measure with a tester or inspect with a tester. Further, the lead wire 102 is hardened by a sealing resin 110, and the lead wire 102 is hardened.
When bent is used from its root part, insulation failure due to cracking of the sealing resin 110 is caused, so that such usage cannot be performed. For these reasons, the usability of the thermal fuse was poor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal fuse which is simple in structure, reduces manufacturing cost, and is excellent in usability.

[0007]

According to a first aspect of the present invention, there is provided a thermal fuse comprising: an insulating outer cylinder;
A pair of caps attached to both ends of the outer cylinder, a pair of terminals housed in the outer cylinder and connected to the respective caps, and a pair of terminals housed in the outer cylinder, and both terminals are simultaneously placed in the radial direction of the outer cylinder. A conductor that is movable from an energized position contacting from the inside to a blocking position that is separated from at least one terminal; and a conductor that is disposed on one side of the conductor and that prevents movement of the conductor to the blocking position before melting. An insulating melt that melts due to a rise in temperature to the rated temperature and allows the conductor to move to the shut-off position, and is disposed on the other side of the conductor and directs the conductor toward the insulating melt before melting. A biasing means for moving the conductor to the shut-off position when the insulating melt is melted while pressing and holding at the energized position, and an insulator for insulating the biasing means and the conductor. It is configured.

Therefore, in a normal state, the insulating melt is solidified, and the conductor is held in the energized position between the insulating melt and the urging means. It flows from the terminal to the conductor to the other terminal to the other cap. Then, when the ambient temperature reaches the rated temperature, the insulating melt is melted, and the conductor is moved to the cutoff position by the urging means. In this state, the conduction state between the terminals is cut off, and the caps are insulated by the outer cylinder and the conductor and the urging means are insulated by the insulator. Flow is interrupted.

Further, in the thermal fuse according to the second aspect, the outer cylinder is made of a transparent material. In this case, the state inside the outer cylinder, that is, the position of the conductor can be visually confirmed from the outside.

In the thermal fuse according to a third aspect of the present invention, the conductor is formed of a sphere. In this case, the frictional resistance when the conductor is pushed by the urging means and moves is reduced.

Furthermore, the thermal fuse according to claim 4 is
The insulator is made up of a sphere. Therefore, the frictional resistance when the insulator is moved by being pushed by the urging means together with the conductor is reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on the best mode shown in the drawings.

FIG. 1 shows an example of an embodiment of a thermal fuse to which the present invention is applied. The thermal fuse includes an insulating outer cylinder 1, a pair of caps 2 attached to both ends of the outer cylinder 1, and a pair of terminals 3, 4 housed in the outer cylinder 1 and connected to the respective caps 2. And housed in the outer cylinder 1,
A conductor 5 movable from an energized position where both terminals 3 and 4 are simultaneously contacted from the radially inner side of the outer cylinder 1 to a cut-off position separated from at least one of the terminals; In the previous state, while preventing the conductor 5 from moving to the cutoff position, the insulating melt 6 that melts at the rated temperature to allow the conductor 5 to move to the cutoff position, and the other side of the conductor 5 The conductor 5 is pressed against the insulative melt 6 before melting and held in the energized position, while the insulative melt 6
Is melted, the urging means 7 for moving the conductor 5 to the blocking position, and the insulator 8 interposed between the urging means 7 and the conductor 5 to insulate them. ing.

The insulating outer cylinder 1 is a glass tube formed of, for example, BC glass. Both ends of the outer peripheral surface of the outer cylinder (hereinafter, referred to as a glass tube) 1 are polished so as to be slightly tapered, so that workability at the time of fitting the cap is improved and roundness of the outer diameter is obtained. I have. That is, the outer peripheral surface of the glass tube 1 is processed only in a necessary and sufficient range. The cross-sectional shape of the glass tube 1 is not limited to a circle, but may be an ellipse, a polygon, or the like. Further, as the glass, it is preferable to use lead glass, BC glass, DC glass, or the like that functions as an electrical insulating material.

Each of the caps 2 fitted to both ends of the glass tube 1 is, for example, a conductive one manufactured by applying a silver plating to a brass molded product. A lead wire 9 is connected to each cap 2 and caulked together with the terminals 3 and 4. Note that each cap 2 does not necessarily have to be conductive, and each terminal 3 and 4 and each lead wire 9 are not required.
When each of the caps 2 can be electrically connected, it is not necessary to make each cap 2 conductive. The lead wire 9 is made of copper and is plated with silver.

Each of the terminals 3 and 4 is manufactured by, for example, applying silver plating to a molded product of zirconium copper having spring properties.
Each of the terminals 3 and 4 is connected to an end plate 3
Strips 3b, 4b are extended from a, 4a, and these strips 3b, 4b are arranged along the inner peripheral surface of the glass tube 1 and separated in the radial direction. Strip 3 of each terminal 3, 4
The tips of b and 4b overlap when viewed from the radial direction of the glass tube 1. This overlapping portion is the current-carrying position of the conductor 5. In addition, when the terminals 3 and 4 are made of zirconium copper, terminals having high elasticity and good contact with the conductor 5 and low electric resistance can be obtained, but the material of the terminals 3 and 4 is zirconium copper. Of course, it is not limited to copper.

The conductor 5 is made of, for example, a copper sphere plated with silver. When the conductor 5 is in the energized position (solid line position in FIG. 1), it contacts both terminals 3 and 4 at the same time and makes a gap between them. It is formed in a size that can be made conductive. That is,
In this energized position, the conductor 5 is in contact with both terminals 3 and 4 at the same time, and the thermal fuse is energized.
The conductor 5 can move inside the glass tube 1 to a blocking position (a position indicated by a two-dot chain line in FIG. 1). In the shut-off position,
The conductor 5 is in contact with only one of the terminals 3, and the thermal fuse is in a cut-off state.

The insulating melt 6 is a temperature-sensitive pellet that rapidly melts at a rated temperature. The insulating melt (hereinafter, referred to as a thermosensitive pellet) 6 is made of the same material as that of the conventional thermal fuse, and detailed description thereof is omitted here. It is suitable to use a material that melts with a temperature error of ± 1.5 degrees or less with respect to the temperature (for example, a temperature-sensitive pellet used in the 4000A series of high-precision temperature fuse (microtemp) manufactured by Murata Manufacturing Co., Ltd.). I have.

The biasing means 7 is, for example, a coil spring. Urging means (hereinafter referred to as a coil spring) 7
Are arranged in a compressed state on the opposite side of the thermosensitive pellet 6 with the conductor 5 interposed therebetween. The insulator 8 is, for example, a sphere made of glass and is interposed between the conductor 5 and the coil spring 7 to prevent the contact therebetween. Note that the insulator 8 may be a plastic ball or a ceramic ball.

According to the thermal fuse configured as described above, the current is cut off as follows. That is, in this temperature fuse, the thermosensitive pellet 6 is solidified in a normal state, and the conductor 5 is sandwiched between the thermosensitive pellet 6 and the coil spring 7 and is stopped at the energized position. 9 → terminal 3 (or 4) → conductor 5 → terminal 4 (or 3) → lead wire 9 and flows well.

When the ambient temperature rises abnormally and reaches the rated value, the thermosensitive pellet 6 is rapidly melted, so that the conductor 5 is pushed by the coil spring 7 and moves to the shut-off position. The conductor 5 and the insulator 8 that moves together with the conductor 5 are spherical, and move smoothly with small frictional resistance during the movement. The conduction between the terminals 3 and 4 is cut off by the movement of the conductor 5, and the space between the caps 2 is formed by the glass tube 1.
Since the conductor 5 and the coil spring 7 are insulated from each other by the insulator 8, the current is interrupted.

The glass tube 1 is transparent, so that the internal state of the thermal fuse can be visually checked. That is, the position and the like of the conductor 5 can be visually confirmed from the outside, and the blown state can be easily determined, so that the thermal fuse is easy to use.

Further, since each lead wire 9 is caulked to the cap 2, it can be bent from the root of the exposed portion, and the degree of freedom of the installation state of the thermal fuse is improved, so that the usability is further improved.

The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in the above description, the insulator 8 is a sphere, but the insulator 8 does not necessarily need to be formed into a sphere, and may be formed into a tappet shape as shown in FIG. There may be. The insulator 8 is not necessarily made of glass, and the material is not particularly limited as long as it can insulate the conductor 5 from the coil spring 7. ) Can be used such as synthetic resin (D648 material).

In the above description, the conductor 5 is a sphere. However, the conductor 5 does not necessarily need to be formed into a sphere, but may be formed into a cup shape as shown in FIGS. 3 and 5, for example. And other shapes. When the conductor 5 is formed into a cup shape, a discharge hole 5a is formed at an appropriate location as shown in the figure, and the molten thermosensitive pellet 6 can be discharged to the insulator 8 side so that the conductor 5 can be discharged. It is desirable to move smoothly to the blocking position.

Further, as shown in FIG. 4, the conductor 5 and the insulator 8 may be integrated. That is, the unit formed by fitting the conductor 5 on the cone surface 8a of the insulator 8 is
The coil spring 7 may be pressed against the thermosensitive pellet 6. By forming the conductor 5 and the insulator 8 into a unit, even after the conductor 5 moves from the energized position (solid line position in the drawing) to the cutoff position (the position indicated by the two-dot chain line in the drawing), And the positional relationship between the conductor 5 and the conductor 5 can be reliably maintained at the blocking position. The coil spring 7 and the conductor 5 are insulated by an insulating ring 10. The insulator 8 is formed of, for example, a resin (D648 material), and the glass tube 1 is formed of DC glass.

Further, in each of the above-described embodiments, the end portions of the strips 3b and 4b of the terminals 3 and 4 are overlapped when viewed from the radial direction of the glass tube 1, but as shown in FIG. Depending on the shape of the conductor 5, it is not always necessary to overlap the end portions of the strips 3b and 4b when viewed from the radial direction of the glass tube 1. That is, even when the end portions of the strips 3b and 4b do not overlap when viewed from the radial direction, the conductor 5 is formed into a bottomed cylindrical shape or the like so that the conductors 5 are formed into the respective strips 3b and 4b.
4b can be contacted simultaneously. In other words, the shape of the conductor 5 and each of the strips 3b, 4b is not particularly limited as long as the conductor 5 arranged at the energized position can simultaneously contact each of the strips 3b, 4b. Strip 3b,
4b may not be arranged in the radial direction of the glass tube 1, but may be arranged so as to be axially separated on the same line as shown in FIG. 6, or may be slightly shifted in the circumferential direction of the glass tube 1. May be arranged. In these cases, when the conductor 5 moves to the temperature-sensitive pellet 6 side due to the melting of the temperature-sensitive pellet 6 and is arranged at the blocking position, the conductor 5 does not straddle between the two strips 3b, 4b. It is provided as follows.

Further, in the above description, the outer cylinder 1 is made of glass. However, it goes without saying that the outer cylinder 1 may be formed of, for example, a transparent synthetic resin having excellent heat resistance. Further, it is not always necessary to make the outer cylinder 1 transparent, and when visual confirmation from the outside is unnecessary, the outer cylinder 1 does not need to be transparent. For example, the outer cylinder 1 may be made of ceramic.

Further, in the above description, the thermal fuse of the type in which the lead wire 9 is connected to each cap 2 is taken as an example. However, the thermal fuse is mounted in a fuse socket without connecting the lead wire to the cap. Of course, the present invention may be applied to a type of thermal fuse.

[0030]

As is apparent from the above description, in the thermal fuse according to the first aspect, the conductor is stopped at the energized position by the insulating melt and the urging means before the melting of the insulating melt. On the other hand, since the conductor is moved to the blocking position by the biasing means after the insulating melt is melted, the number of components can be reduced and the assembling operation can be simplified. For these reasons, the productivity of the thermal fuse is improved, and the production cost can be reduced.

Further, in the thermal fuse according to the second aspect, since the insulating outer cylinder is made transparent, the state in the outer cylinder can be visually confirmed from the outside. Therefore, the blown state of the thermal fuse can be easily confirmed without using a tester or a tester, and the usability is improved.

Furthermore, in the thermal fuse of the third aspect, the conductor is formed as a sphere, and in the thermal fuse of the fourth aspect, the insulator is formed as a sphere. The smooth movement of the thermal fuse can be achieved by smoothly moving the conductor to the cutoff position, that is, the current can be reliably cut off.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a thermal fuse according to the present invention.

FIG. 2 is a cross-sectional view of a main part of a thermal fuse according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a main part of a thermal fuse according to a third embodiment of the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of a thermal fuse according to the present invention.

FIG. 5 is a cross-sectional view of a main part of a thermal fuse according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view of a main part of a thermal fuse according to a sixth embodiment of the present invention.

FIG. 7 is a sectional view of a conventional thermal fuse.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass tube (outer cylinder) 2 Cap 3, 4 Terminal 5 Conductor 6 Thermosensitive pellet (insulating melt) 7 Coil spring (biasing means) 8 Insulator 9 Lead wire

Claims (4)

[Claims] 1. An insulating outer cylinder, a pair of caps attached to both ends of the outer cylinder, and housed in the outer cylinder,
A pair of terminals respectively connected to the respective caps, housed in the outer cylinder, from an energizing position in which both terminals are simultaneously contacted from a radially inner side of the outer cylinder to a blocking position separated from at least one terminal. Movable conductor, disposed on one side of the conductor, preventing movement of the conductor to a shut-off position in a state before melting, while melting by increasing the temperature to a rated temperature to form the conductor. An insulating melt that allows movement to the cutoff position, and the insulating melt is disposed on the other side of the conductor, and the conductor is pressed toward the insulating melt before melting and held at the current-carrying position, while the insulation A thermal fuse, comprising: urging means for moving the conductor to a shut-off position when the fusible melt is melted; and an insulator for insulating the urging means from the conductor. 2. The thermal fuse according to claim 1, wherein said outer cylinder is transparent. 3. The thermal fuse according to claim 1, wherein the conductor is a sphere. 4. The thermal fuse according to claim 1, wherein the insulator is a sphere.