JPH1173871A - Fuse with press pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuse with a press pattern capable of surely interrupting an overcurrent with no dispersion in a fixed time and capable of easily applying a fail-safe function to a current opening/closing switch mounted on the press pattern. SOLUTION: A press pattern 3 is provided with a cut section 6 cut with a part of the press pattern 3, and the cut section 6 is connected by a conductive material 7. When an overcurrent flows in a circuit including the press pattern 3 for a fixed time and the conductive material 7 becomes a fixed temperature, it is fused and dropped from the cut section 6 by its tare weight to open the circuit, and the overcurrent flowing in the circuit is interrupted. Thereby, the dispersion of the time until the overcurrent is interrupted is reduced, and a stable fail-safe function is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuse having a fail-safe function when an overcurrent flows through a current switch using a press pattern.

[0002]

2. Description of the Related Art Conventionally, as a countermeasure (fail-safe function) when an overcurrent flows in a circuit having a current switch (hereinafter, referred to as a basic switch), the following three countermeasures are generally known. I have. Printed circuit board (hereafter P
When an overcurrent flows in the circuit, the fusible metal body constituting the pattern fuse is blown to cut off the overcurrent flowing in the circuit. Add a fail-safe function to the basic switch body.
As an example, the basic switch is a micro switch having a snap action function, and when an overcurrent flows, the leaf spring constituting the switch is blown or the contact material of the push button is melted. All parts on the circuit are configured to have as large a current capacity as possible to withstand overcurrent.

[0003]

However, the above-mentioned conventional fail-safe functions have the following problems. Can be used only when PWB is used as the mounting board. In other words, a press pattern made of a metal plate is used as a mounting board, and a basic switch is placed on a resin insert base attached to the press pattern, or a type in which a contact opening / closing mechanism is directly attached to the insert base. Cannot be pressed under a certain condition (generally, only the same pattern width as the plate thickness can be reduced, but this does not lead to fusing). Therefore, this method cannot be applied, and a fail-safe function cannot be added to such a configuration (such as an insert base using a press pattern + a basic switch). In the above method, overcurrent can be cut off reliably, but in order to mount such a function on a small basic switch, it is necessary to use a complicated contact opening and closing mechanism such as a snap action , Which leads to a significant cost increase.
In the method of (1), an overcurrent continues to flow beyond the specifications, and a resin member constituting the switch may be thermally damaged by overheating. Therefore, a more positive fail-safe function is required.

[0004] Similarly to the pattern fuse on the PWB, it is conceivable to simply provide a pattern fuse on the press pattern. However, due to various factors such as the thickness of the press pattern, the pattern width, and the use environment, it is difficult to cut the fuse. The variation in the time required is extremely large, and there is a problem in practical use. In the case of a pressed product, since the melting point of the pressed material (copper, brass, etc.) is high, it is necessary to make the pattern width narrower than the plate thickness in order to melt the resin material below the deflection temperature under load. However, in press working, there is a limit that processing cannot be performed narrower than the plate thickness. Therefore, there is a problem in that the base resin is actually heated before the pattern fuse is blown, resulting in the worst heat loss.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. When an overcurrent flows through a circuit including a press pattern, the overcurrent can be reliably cut off for a fixed time without variation. Another object of the present invention is to provide a fuse using a press pattern that can easily add a fail-safe function to a current switching switch using a press pattern as a mounting substrate, or a current switching switch itself.

[0006]

According to the present invention, a switch is mounted on a press pattern formed by stamping a metal plate into a predetermined shape, and includes the press pattern. A fuse using a press pattern configured to open this circuit when an overcurrent flows in the circuit, and a cut portion formed by cutting a part of this press pattern is provided on the press pattern. The cut portion is connected by a conductive material that melts at a relatively low temperature (lower than the deflection temperature of the resin material), and when an overcurrent flows through the circuit, the conductive material melts.
Further, the circuit is opened when the conductive material falls from the cut portion by its own weight.

In this configuration, an overcurrent flows in a circuit including a press pattern for a certain period of time, and when the conductive material reaches a certain temperature, it melts, falls by its own weight from a cut portion, opens the circuit, and opens an overcurrent flowing in the circuit. Is shut off. By controlling the amount of conductive material to be used, the amount of heat generated at that portion becomes constant, so that the variation in the time until overcurrent interruption is reduced, and a stable fail-safe function is obtained. When, for example, solder is used as the conductive material, the melting temperature of the solder is close to the heat-resistant temperature of a resin member such as a switch case, so that the switch can be prevented from being thermally damaged. In addition, “relatively low temperature” means the heat resistant temperature of the resin (2
90 to 220 ° C.) (180 to 190 ° C.).

[0008] The invention described in claim 2 is the first invention.
In the overcurrent fuse using the press pattern described in (1), there are continuously two or more cut portions, each of which is connected by a conductive material. In this configuration, when an overcurrent flows in the circuit and the conductive material melts, the conductive material and a part of the press pattern between the cut portions drop from the cut portion by its own weight, so that the overcurrent flowing in the circuit is cut off. can do.

[0009] The invention described in claim 3 is the first invention.
Alternatively, in the fuse using the press pattern according to claim 2, a resin base is attached to the press pattern, the cut portion is exposed from the opening of the resin base, and is located below the position where the press pattern exists. The opening of the resin base has a shape in which the bottom is widened in the falling direction at the time of fusing of the conductive material. In this configuration, even if the press pattern is inclined with respect to the horizontal direction, when the conductive material melted by the overcurrent falls, the drop is not hindered by the opening of the resin base.

[0010] The invention described in claim 4 is the first invention.
Alternatively, in the fuse using the press pattern according to claim 2, this press pattern is used as a pattern inside the switch instead of mounting the switch on the press pattern. In this configuration, a fail-safe function is added to the switch itself, and it is possible to prevent thermal damage to the switch, as in the above-described claims 1 and 2.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1A and 1B are side sectional views showing a normal state and a state at the time of fusing of a circuit including a fuse using a press pattern according to the present embodiment. The fuse 1 is provided on a battery line of a circuit having a basic switch 2 for opening and closing a current, and when an overcurrent flows through the circuit, opens the circuit and cuts off the overcurrent. The basic switch 2 for opening and closing the current is made of one piece of copper,
It is mounted on a press pattern 3 formed by press-punching a metal plate such as brass into a predetermined shape. Above and under this press pattern 3, a resin insert base 4 functioning as an insulator is covered. Is being worn.
The insert base 4 is provided with an opening 5, and the opening 5 a below the position where the press pattern 3 is located has a shape whose skirt is widened downward.

A cut portion 6 formed by cutting a part of the press pattern 3 is provided so as to be exposed from the opening 5 of the insert base 4. A conductive material 7 (hereinafter, referred to as solder), such as solder, which melts at a temperature substantially equal to 200 to 220 ° C. is provided.

Further, the fuse 1, the basic switch 2, etc.
The case 8 is protected by the case 8
A confirmation hole 8a for confirming whether or not the solder 7 of the fuse 1 has melted is provided at a position directly below. In addition,
The insert base 4 is supported by a support member 9 extending from the case 8 (the cover on the upper side of the basic switch is not shown).

Because of the above configuration, FIG.
As shown in (b), an overcurrent flows through the circuit for a certain period of time, and when the solder 7 reaches a certain temperature, it melts, falls under its own weight from the cutting part 6, opens the circuit, and cuts off the overcurrent flowing through the circuit. You. As a result, variation in the time until the overcurrent is interrupted is reduced, and a stable fail-safe function can be realized. Further, since the melting temperature of the solder 7 is close to the heat resistant temperature of the resin members such as the basic switch 2 and the base 4, the switch 2 can be prevented from being thermally damaged.
Furthermore, by checking the confirmation window 8a of the case 8 from the outside and confirming whether or not the confirmation hole 8a is closed with the solder 7,
The state of the fuse 1 can be easily confirmed.

The fuse 1 has an insert base 4
Since the fuse 1 can be provided anywhere, for example, if the fuse 1 is provided at a position where the influence of heat generated from another resistor or the like (not shown) on the solder 7 is reduced, the solder 7 can be provided.
Can be kept constant to some extent, and stable fail-safe can be realized. In addition, insert base 4
Since there is a large design margin above, the size and position of the fusing portion can be freely designed according to the specifications.
In addition, the switch 2 mounted on the press pattern 3
A fail-safe function can be easily added with a slight increase in cost. In this case, the switch 2 does not require a special quality contact material or the like having a high heat radiation effect, so that the cost can be reduced as compared with a micro switch having the same function. Further, by forming the opening 5a below the position where the press pattern 3 is located in such a manner that the hem expands in the falling direction when the solder 7 is blown, the press pattern 3 is inclined obliquely with respect to the horizontal direction. In this state, the solder 7 melted by the overcurrent can be smoothly dropped without adhering to the insert base 4, and the fail-safe function can be reliably and stably achieved.

Further, in the case of the pattern fuse provided on the press pattern, it is difficult to accurately obtain the width of the pattern fuse by the press work, and the time until the fusing is varied, and the press work is difficult. Since there is a limit to a possible pattern width, it is difficult to blow the resin at a temperature lower than the resin temperature. However, in the fuse 1 according to the present invention, a cut portion 6 is provided in the press pattern 3 and the space between the cut portions 6 is soldered. Since the connection is made by the connection 7, there is no variation in the time until the fusing, and a stable fail-safe function can be obtained in which the fusing can be performed at a temperature at which the resin material does not lose heat.

2 and 3 are views for explaining an example of a method of forming the fuse 1. FIG. 2 is an external view near a cut portion, and FIG. 3 is a side sectional view near a cut portion. In order to put the solder 7 on the cutting section 6, the solder 7 supplied from the solder feeder 21 is melted by the soldering iron 22 with the solder fixing jig 20 approaching the cutting section 6 from below. 6 is connected by solder 7. As a result, the solder 7 can be applied to the cut portion 6 to form a fuse. The soldering operation may be performed by a solder robot or manually.

(Second Embodiment) FIGS. 4A and 4B are side sectional views showing a normal state and a state at the time of fusing of a circuit including a fuse using a press pattern according to the present embodiment, respectively. is there. In the fuse 1 of the present embodiment, cut portions 6 are continuously provided at two locations with a part 3a of the press pattern interposed therebetween, and the cut portions 6 are connected by solder 7. As shown in FIG. 2B, when an overcurrent flows in the circuit, the solder 7 is melted, and a part 3a of the press pattern and the solder 7 are cut by their own weight as shown in FIG. Fall more. As a result, a more reliable and stable fail-safe function can be obtained as compared with the fuse of the above-described first embodiment.

The present invention is not limited to the above embodiment, but can be variously modified. For example, in the above embodiment,
Although the fuse was installed on the battery line, other lines,
For example, a fuse may be provided on the ground line,
Further, it can be used for the pattern of the switch itself.

[0020]

As described above, according to the present invention, the cut portions provided on the press pattern on which the switches are mounted are connected by a conductive material that melts at a relatively low temperature.
When an overcurrent flows in the circuit for a certain period of time and the conductive material reaches a certain temperature, the conductive material melts and falls by its own weight from the cut part,
The circuit is opened, and an overcurrent flowing to the circuit including the press pattern can be cut off. As a result, the variation in the time until the overcurrent is interrupted is reduced, and the switch can be prevented from being thermally damaged. Further, when the switch itself does not have a fail-safe function, a fail-safe function, which is difficult to be provided by a switch mounted on a conventional press pattern, can be easily added with almost no increase in cost. Further, since this fuse can be provided anywhere on the press pattern, the heat generation condition of the conductive material in the cut portion can be kept constant to some extent, and a stable fail-safe function can be realized. In addition, since there is a large design margin on the press pattern, the size and position of the fusing portion can be freely designed according to the specifications. Further, it is not necessary to use an expensive contact material having a high heat radiation effect for the switch, and the cost can be reduced as compared with a micro switch having the same function.

Further, according to the present invention, since two or more cut portions are continuously provided on the press pattern and each of them is connected by a conductive material, when an overcurrent flows,
The conductive material melts at a certain temperature, and a part of the press pattern between the conductive material and the cut portion falls by its own weight. Thereby, a more reliable and stable fail-safe function can be obtained.

Further, according to the present invention, since the opening of the resin base below the position where the press pattern is located is formed to have a shape that is wider in the hem in the dropping direction when the conductive material is blown, the press pattern is formed. Even in the state inclined with respect to the horizontal direction, the molten conductive material can be smoothly dropped, and the fail-safe function can be reliably and stably achieved.

Further, according to the present invention, since the fuse using the press pattern is provided on the press pattern in the switch, a fail-safe function can be easily added to the switch itself without substantially increasing the cost. it can. Further, it is not necessary to use an expensive contact material or the like having a high heat radiation effect, so that the cost can be reduced as compared with a microswitch having the same function.

[Brief description of the drawings]

FIGS. 1A and 1B are side sectional views showing a normal state and a state at the time of fusing of a fuse using a press pattern according to a first embodiment of the present invention, respectively.

FIG. 2 is an external view of the vicinity of a cut portion constituting a fuse.

FIG. 3 is a side sectional view showing a vicinity of a cut portion constituting a fuse;

FIGS. 4A and 4B are side sectional views showing a normal state and a state at the time of fusing of a fuse using a press pattern according to a second embodiment of the present invention, respectively.

[Description of Signs] 1 Fuse 2 Switch 3 Press Pattern 4 Insert Base (Resin Base) 5 Opening 6 Cut Section 7 Conductive Material (Solder)

Claims (4)

[Claims] A switch is mounted on a press pattern formed by stamping a metal plate into a predetermined shape, and the circuit is opened when an overcurrent flows in a circuit including the press pattern. A fuse, wherein a cut portion obtained by cutting a part of the press pattern is provided on the press pattern, and the cut portion is connected by a conductive material that melts at a relatively low temperature; When an overcurrent flows through, the conductive material melts,
Further, a fuse using a press pattern, wherein the circuit is opened by the conductive material falling from the cut portion under its own weight. 2. The cutting section is continuously provided at two or more locations,
The fuse using a press pattern according to claim 1, wherein each of the fuses is connected by a conductive material. 3. A resin base is attached to the press pattern, the cut portion is exposed from an opening of the resin base, and an opening of the resin base below a position where the press pattern is located. 2. A shape in which a skirt is widened in a falling direction at the time of fusing the conductive material.
A fuse using the press pattern according to claim 2. 4. A fuse using a press pattern according to claim 1, wherein the switch is mounted on the press pattern, and the press pattern is used as a pattern inside the switch. .