JPH027486B2 - - Google Patents

Description

DETAILED DESCRIPTION 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.

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 concern 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 retaining screw 22, and the cross bar 18 is further connected to the movable iron core 14.
Then, when the operating coil 16 is energized, the movable core 14 is magnetically attracted to the fixed core 12 against a separation spring (not shown), which causes the movable contact 20A to
The fixed contact 24A is configured to come into contact with the fixed contact 24A.

Here, when the power to the operating coil 16 is cut off, the movable contact 20A and the fixed operating point 24A are separated by the action of the separation spring. At this time, an arc 32 is generated between the contacts 20A and 24A, but this arc 32 is extinguished by the metal arc extinguishing plates 34 and 36, 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 the contacts 20A and 24A is attracted to the first metal arc-extinguishing plate 34 made of a magnetic material and is elongated as shown by the reference numeral 32A. In this case, if the fixed contact 24 is U-shaped as shown in FIG. Stretched. As the arc 32 is stretched, the arc voltage increases, so dielectric breakdown occurs between the fixed contact 24 and the first metal arc extinguishing plate 34 and between the first metal arc extinguishing plate 34 and the movable contact 20A, and the arc 32A is divided into two arcs 32B and 32C. One of the divided arcs 32C is attracted by the second metal arc-extinguishing plate 36 and is driven by the magnetic field created by the current flowing through the fixed contact 24, so that it is elongated as shown by the reference numeral 32D. When this arc 32D is stretched and the arc voltage increases, the arc 32D
is divided into two arcs 32E and 32F.
The arc 32 finally becomes three arcs 32B, 32
E and 32F, the arc is extinguished at the current zero point, and the current is cut off.

In conventional switches, arc extinguishing is performed as described above, but since the distance between the first metal arc extinguishing plate 34 and the fixed contact 24 is small, the first metal arc extinguishing plate 34 and the fixed contact Arc 32D between contacts 24
Therefore, the arc 32D was difficult to be divided into two arcs 32E and 32F. For this reason, the arc 32 tends to stick between the tip of the first metal arc-extinguishing plate 34 and the fixed contact 24. As a result, electric field concentration tends to occur at one end of the arc 32D, and the electric field concentration also occurs at the tip of the first metal arc-extinguishing plate 34, which has poor thermal conductivity, resulting in problems such as extremely reduced interrupting performance. Ta.

This invention was made in view of the above-mentioned conventional problems, and its purpose is to improve the interrupting performance by preventing one end of the arc from concentrating on the tip of the arc-extinguishing plate, where heat conduction is poor and electric field concentration occurs. The object of the present invention is to provide a switch that can improve the

In order to achieve the above object, the present invention includes a fixed contact joined to a fixed contact, a fixed contact joined to a movable contact, and a commutating electrode provided on the back side of the movable contact. It is characterized by comprising a U-shaped metal arc-extinguishing plate having a surface facing the commutating electrode, a surface facing the fixed contact, and a surface facing the side surface of the movable contact.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 4 and FIG. 5 show an embodiment of a main part of a switch according to the present invention. The switch, a part of which is shown in the same figure, is
A commutation electrode 40 is newly provided, and
This differs from the conventional one described above in that the metal arc-extinguishing plate 38 is formed in a U-shape. One surface of the metal arc-extinguishing plate 38 faces the fixed contact 24, and the commutation electrode 40 is provided on the opposite surface thereof.

Here, the arc 32 generated between the movable contact 20A and the fixed contact 24A is attracted to a metal arc-extinguishing plate 38 made of a magnetic material, and is elongated as shown by the reference numeral 32A. If the fixed contact 24 is formed in a U-shape having three surfaces as shown in FIG.
The arc 32 is driven by the magnetic field created by the current flowing through the stationary contact 24, thereby elongating the arc 32 further. As the arc 32 is stretched, the arc voltage increases, so the fixed contact 24
Dielectric breakdown occurs between the metal arc extinguishing plate 38 and the metal arc extinguishing plate 38 and the movable contact 20, causing an arc 32A.
is divided into two arcs 32B and 32C.
One of the divided arcs 32C is connected to the metal arc extinguishing plate 38
is driven by a magnetic field created by a current flowing through it, and is stretched as shown at 32D. When this arc 32D is stretched and the arc voltage increases, dielectric breakdown occurs between the metal arc extinguishing plate 38 and the commutating electrode 40, and the arc 32D becomes like an arc 32G. As a result, the two arcs 32B and 32G are extinguished at the current zero point, and the current is interrupted.

As described above, in the switch of the present invention, both ends of the two arcs 32C and 32G are connected to three flat parts where electric field concentration is difficult to occur and which have good heat conduction, namely, the commutation electrode 40, the metal arc extinguishing plate 38, Fixed contact 2
Since the current reaches zero point at the plane part of 4 and is extinguished,
Excellent breaking performance can be obtained.

Although the fixed contact 24 has a U-shape in the embodiment, it is needless to say that the shape is not limited to this.

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 difficult to occur and has good thermal conductivity, so the breaking performance can be significantly improved compared to the conventional one. Can be done.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an example of a conventional switch, Figure 2 is an enlarged view of the main part of the switch in Figure 1, and Figure 3 is a cross-sectional view of an example of a conventional switch.
FIG. 4 is a perspective view of essential parts showing an embodiment of the present invention, and FIG. 5 is an explanatory diagram of the operation of the embodiment of the present invention. The same members in each figure are given the same reference numerals, 20 is a movable contact, 20A is a movable contact, 24 is a fixed contact, 24A is a fixed contact, 32, 32A to 32G are arcs, 38 is a metal arc extinguishing plate, 40 is a commutation electrode.

Claims (1)

[Claims] 1 A fixed contact joined to a fixed contact, a movable contact joined to a movable contact, a commutation electrode provided on the back side of the movable contact, and a surface facing the commutation electrode and the fixed contact. A switch comprising a U-shaped metal arc-extinguishing plate having opposing surfaces and a surface opposing a side surface of a movable contact.