JP2574056Y2 - Reed switch - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention operates by an external magnetic field provided by a permanent magnet, a coil, and the like.
The present invention relates to a small, fast-acting, high-reliability reed switch that can be used for a reed relay or the like.

[0002]

2. Description of the Related Art A reed switch is used for opening and closing a switch contact by a magnetic field. The reed switch is used in many applications because the contact operates and recovers quickly and the contact reliability is high. Such a reed switch mainly includes a pair of reed pieces each having a tip portion serving as a contact portion of the reed switch, and a container such as a glass tube or a ceramic tube for accommodating the tip portion of the reed switch. Conventionally, the lead piece is formed by pressing or punching a permalloy (hereinafter, referred to as 52 alloy) wire material containing, for example, about 52% nickel into a predetermined shape.

[0003]

By the way, in the conventional reed switch, when the current flowing through the contact of the reed switch becomes high, the temperature of the contact portion of the reed switch becomes close to the Curie temperature of 52 alloy which is a material of the reed switch due to heat generation. Reach For this reason, when the current flowing through the contact of the reed switch increases, the magnetic flux density of the reed decreases, and even if an external magnetic field is applied to the reed switch, it is fatal as a reed switch such as contact opening or contact bounce. There is a problem that the magnetic characteristics are deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a reed switch capable of suppressing magnetic deterioration due to heat generation at the contacts of the reed switch and improving the contact performance. It is an object.

[0005]

According to the present invention, there is provided a reed switch in which a pair of reed pieces are sealed in a container with their tips opposed to each other with a predetermined gap therebetween. The lead piece was formed of a wire composed of a core portion made of pure iron and an outer peripheral portion made of an alloy of iron and nickel and covering around the core portion.

[0006]

The heat generated by the current flowing through the contact of the reed switch is proportional to the value obtained by dividing the specific resistance of the material of the reed by the thermal conductivity. According to the reed switch of the present invention,
The core of the lead wire is made of pure iron, which has low specific resistance and high thermal conductivity compared to 52 alloy.
Heat generated by the current flowing through the contact of the reed switch is suppressed. Moreover, pure iron has a higher Curie temperature at which the saturation magnetic flux density disappears as compared with the 52 alloy, so that even when the current flowing through the contact of the reed switch increases, the reed switch hardly causes magnetic deterioration. In addition, the ferromagnetic material, the thermal expansion coefficient matches that of a container such as a glass tube for enclosing the lead piece, and the outer periphery of permalloy having a predetermined composition that is resistant to rust. Due to the coating, a reed switch is obtained which retains good magnetic properties and has the reed piece firmly fixed to the container.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a wire of a reed piece constituting a reed switch of the present invention, and FIG. 2 is a schematic sectional view showing an example of the reed switch of the present invention. In the figure, reference numerals 1 and 2 denote a pair of lead pieces. The lead pieces 1 and 2 are each composed of a core 11 made of pure iron and an outer peripheral portion 12 made of 52 alloy and covering around the core 11. It is formed of a wire 10 having a diameter of about 0.3 to 0.76 mm. That is, the lead pieces 1 and 2 are formed by pressing the wire material 10 configured as described above to form the lead pieces 1 and 2 into a predetermined shape.
The tip portions 1a and 2b formed to a thickness of about 3 mm are magnetically annealed as necessary, and are subjected to plating surface treatment using a predetermined metal material.

In the reed switch, the tip portions 1a and 2b of the pair of reed pieces 1 and 2 formed as described above are opposed to each other with a predetermined gap 4 therebetween, together with an inert gas and a glass tube or a ceramic tube. Etc., and is formed by fixing the lead pieces 1, 2 to the container 3 at the sealing portions 5, 6.

In the above reed switch, when an external magnetic field is applied, both ends of the reed pieces 1 and 2 are magnetized to the N pole or the S pole, respectively, and the tips 1a and 2b have different polarities and are attracted to each other. Contact. That is, the tip 1
The contacts a and 2b are brought into a contact state, and the contact of the reed switch is closed. When the magnetic field is removed, the tip portions 1a, 2a
b is separated from each other by the elastic force of the reed pieces 1 and 2 and returns to the original facing state, and the contact of the reed switch is opened.

Here, the lead pieces 1 and 2 are, as described above,
It is formed of a wire rod 10 composed of a core 11 made of pure iron and an outer peripheral part 12 made of a 52 alloy. Core 11
Pure iron has a lower specific resistance and a higher thermal conductivity than the 52 alloy used as a conventional lead wire. On the other hand, the heat generated by the current flowing through the contact of the reed switch is proportional to the value obtained by dividing the specific resistance by the thermal conductivity. Therefore, by forming the lead pieces 1 and 2 using the wire 10 having the core 11 made of pure iron, the tip 1a,
The heat generation of 2b is considerably suppressed. In addition, pure iron has a considerably higher Curie temperature at which the saturation magnetic flux density disappears as compared with 52 alloy, so that the lead piece 1 using the wire 10,
In the case of No. 2, even if the current flowing through the contact of the reed switch becomes high, the magnetic deterioration hardly occurs. As a result, contact separation, contact bounce, and the like hardly occur, and the contact performance of the reed switch is improved. On the other hand, the outer peripheral portion 12 made of 52 alloy
Is a ferromagnetic material, has a coefficient of thermal expansion matching that of a container 3 such as a glass tube for enclosing the lead pieces 1 and 2, and has the property of being resistant to rust. Therefore, the reed pieces 1 and 2 can be firmly fixed to the container 3, and a reed switch can be manufactured stably while maintaining good magnetic properties.

As described above, according to the reed switch of the present embodiment, it is possible to suppress the magnetic deterioration due to the heat generated at the contact of the reed switch, and to improve the contact performance. In addition, it can be manufactured stably. Therefore, it can be used as a high-current reed switch and a high-power reed switch, and can also be used as a small-sized, fast-acting, highly-reliable reed switch for proximity switches, reed relays, and the like.

[0012]

As described above, according to the reed switch of the present invention, pure iron having a low specific resistance, a high thermal conductivity, and a high Curie temperature is used as the core of the reed piece as compared with the 52 alloy. Therefore, even if the current flowing through the contact of the reed switch becomes high, magnetic deterioration hardly occurs. Therefore, the occurrence of contact separation, contact bounce, and the like can be suppressed, and the contact performance of the reed switch can be improved. Further, the wire is a ferromagnetic material as an outer peripheral portion covering the core portion, has a coefficient of thermal expansion matching that of a container such as a glass tube for enclosing the lead piece, and has a predetermined composition that is strong against rust. Since permalloy is used, it is possible to obtain a reed switch having good magnetic properties and tightly adhered reed pieces. Therefore, the reed switch of the present invention can be used as a high-current reed switch and a high-power reed switch, and can also be used as a small-sized and fast-operating high-reliability reed switch in proximity switches and reed relays.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a wire of a reed piece constituting a reed switch of the present invention.

FIG. 2 is a schematic sectional view showing an example of the reed switch of the present invention.

[Explanation of symbols]

 1, 2 Lead piece 1a, 2b Tip 3 Container 4 Gap 10 Wire 11 Core 12 Outer periphery

Claims (1)

(57) [Scope of request for utility model registration] 1. A reed switch in which a pair of reed pieces are sealed in a container with their tip portions facing each other with a predetermined gap therebetween, wherein the reed pieces are a core made of pure iron, A reed switch comprising a wire made of a nickel alloy and having an outer peripheral portion covering the periphery of the core.