JPH0521285B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a switch that switches on and off current, and particularly to improvements in its arc-extinguishing mechanism.

[Prior art]

For example, in a switch used as an electromagnetic contactor or a molded circuit breaker, how to improve the breaking performance of the switch is a matter of greatest interest to those skilled in the art.

FIG. 1 shows an example of an electromagnetic contactor as a conventional switch. The contactor shown in the figure includes a mounting base 10, a fixed core 12, a movable core 14, an operating coil 16, a crossbar 18, a movable contact 20 to which a movable contact 20A is joined, a presser spring 22, and a fixed contact 24A. The terminal includes a fixed contact 24, a terminal screw 26, a base 28, a cover 30, and the like.

The movable contactor 20 is pressed against the lower edge surface of the square window of the cross bar 18 by a presser spring 22, and the cross bar 18 is further connected to the movable iron core 14.
When the operating coil 16 is energized, the movable core 14 is magnetically attracted to the fixed core 12 against a tripping spring (not shown), and as a result, the movable contact 20
A fixed contact 24A is adapted to make contact.

Here, when the power to the operating coil 16 is cut off, the movable contact 20A and the fixed contact 24A are separated by the action of the tripping spring. At this time, an arc 32 occurs between both contacts 20A and 24A, but
This arc 32 is extinguished by a metal arc extinguishing plate 34, thereby interrupting the current.

FIG. 2 shows a portion near the fixed contact 24A, and FIG. 3 shows a process in which an arc 32 generated between both contacts 20A and 24A is extinguished. Here, the arc 32 generated between both contacts 20A and 24A is attracted to a metal arc extinguishing plate 34 made of a magnetic material, and is
It is stretched as shown at 2A. In this case, since the fixed contact 24 has a U-shape as shown in FIG. 3, the arc 32 is driven by the magnetic field created by the current flowing through the fixed contact 24, which causes the arc 32 to be further stretched. It will be done. As the arc 32 is stretched, the arc voltage increases, so dielectric breakdown occurs between the fixed contact 24 and the metal arc-extinguishing plate 34, and between the metal arc-extinguishing plate 34 and the movable contact 20A, and the arc 32A becomes two arcs. 32B and 32C
After that, the arc is extinguished at the current zero point, and the current is interrupted.

In conventional switches, the arc is extinguished as described above, but as shown in Figure 3, the arc 32
C is the tip of the metal arc-extinguishing plate, and the arc 32B is extinguished at the tip of the movable contact 20. That is, because the arc is extinguished at the tip where electric field concentration tends to occur and heat conduction is poor, conventional switches have been unable to obtain sufficient breaking performance.

[Summary of the invention]

This invention was made in view of the conventional problems mentioned above, and its purpose is to improve interrupting performance by avoiding concentration of one end of the arc at the tip of the arc-extinguishing plate, where heat conduction is poor and electric field concentration occurs. It is an object of the present invention to provide a switch which is improved and can prevent damage to a cover due to arc heat.

In order to achieve the above object, the present invention bends each end of a movable contact and a fixed contact, and makes the plane of the bent part face a metal arc-extinguishing plate, and also makes the metal arc-extinguishing plate It is configured to have a U-shaped cross section and surround the arc space where the arc occurs, thereby avoiding the disadvantages of conventional switches.

[Embodiments of the invention]

FIG. 4 shows a main part of a switch according to an embodiment of the present invention, and FIG. 5 shows an inclined view of a metal arc-extinguishing plate and a fixed contact.

As shown in FIG. 5, the metal arc-extinguishing plate 34 has a U-shaped cross section, and the fixed contact 24 has a rising piece 24C at one end, and a parallel piece 24D is folded from the upper end of the rising piece 24C. It is formed into a curve, and then its tip is bent toward the side opposite to the movable contact (lower side), and this bent tip portion 24B is configured to face the metal arc-extinguishing plate 34. Further, the tip end 20B of the movable contact 20 is bent toward the side opposite to the fixed contact, and faces the metal arc-extinguishing plate 34.

Here, the arc 32 generated between the movable contact 20A and the fixed contact 24A is attracted to the metal arc-extinguishing plate 34 made of a magnetic material, and is elongated as shown by the reference numeral 32A. Since the fixed contact 24 is formed into a U-shaped shape having three pieces 24C, 24D, and 24B as shown in FIG.
The arc 32 is driven by the magnetic field created by the current (arrow X) flowing through the arc 32, thereby stretching the arc 32 further. As the arc 32 is extended, the arc voltage becomes higher, so dielectric breakdown occurs between the fixed contact 24 and the metal arc extinguishing plate 34 and between the metal arc extinguishing plate 34 and the movable contact 20, and the arc 32A increases as described above. is divided into two parts 32B and 32C. As a result, two arcs 32B and 3
When 2C is at the current zero point, the arc is extinguished and the current is cut off.

As described above, in the switch of the present invention, the divided arcs 32B and 32C are generated between the bent plane portion 20B of the movable contact 20 and the flat plate portion of the metal arc-extinguishing plate 34 and between the fixed contact 24. The arc is extinguished between the bent flat tip portion 24B and the flat plate portion of the metal arc extinguishing plate 34.

That is, since both ends of the arcs 32B and 32C are extinguished at flat parts where electric fields are less likely to concentrate and where heat conduction is good, the breaking performance can be improved compared to the conventional case. In addition, in the embodiment of the present invention, as shown in detail in the perspective view of FIG.
4 has a U-shaped cross section. This U-shaped metal arc extinguishing plate 34 is arranged so as to surround the arc generation space between the movable contact 20A and the fixed contact 24A. Therefore, in the embodiment of the present invention, it is possible to prevent damage to the side wall 30A of the cover 30 shown in FIG. Can be removed.

〔Effect of the invention〕

As described above, the switch according to the present invention extinguishes the arc by reaching the current zero point in the flat part where electric field concentration is unlikely to occur and which has good heat conduction, so it is possible to significantly improve the breaking performance compared to the conventional one. can. Also,
The arc space where the arc occurs is surrounded by a metal arc-extinguishing plate with a U-shaped cross section.
It is also possible to prevent short-circuit accidents between phases due to holes in the cover caused by arc heat.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view of an example of a conventional switch, Fig. 2 is a perspective view of the main part of Fig. 1, and Fig. 3 is a partial cross-sectional view of an example of a conventional switch.
FIG. 4 is a cross-sectional view of a main part of an embodiment of the present invention, and FIG. 5 is a perspective view of a main part of an embodiment of the present invention. In the figure, 20 is a movable contact, 20A is a movable contact,
20B is a bent portion of the movable contact, 24 is a fixed contact, 24A is a fixed contact, 24B is a bent portion of the fixed contact, 32, 32A to 32C are arcs, and 34 is a metal arc extinguishing plate. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A movable contact, a movable contact joined to the movable contact, and a U-shaped fixing having a parallel piece facing the movable contact at the upper end of the rising piece at one end. a contact, a fixed contact joined to the parallel piece portion of the fixed contact and facing the movable contact, and the fixed contact and the movable contact arranged opposite to each other in close proximity to the ends of the movable contact and the fixed contact. In a switch equipped with a metal arc-extinguishing plate that extinguishes an arc generated when the two contacts open, each end of the movable contact and the fixed contact is bent parallel to each other in opposite directions. The opening/closing device is characterized in that the flat surface of the bent portion faces the metal arc-extinguishing plate, and the metal arc-extinguishing plate is formed to have a U-shaped cross section so as to surround the arc space in which the arc is generated. vessel.