JPH0548334Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an improvement of a DC electromagnetic contactor, particularly a DC electromagnetic contactor that has an arc extinguishing device and switches and closes a DC load.

[Prior art]

Many of the DC electromagnetic contactors that have been provided in the past have often been used with lower ratings than AC electromagnetic contactors.

The structure of such a conventionally used AC magnetic contactor will be explained with reference to FIG.

A terminal 12 is fixed to the base 10 with a screw so that a part thereof protrudes outside the base 10, and a fixed contact 16 having a generally U-shaped overall shape has a fixed contact 14 fixed to the upper surface of the terminal 12. is fixed with screws. Furthermore, an arc runner 18 having an upwardly projecting tip is fixed to the fixed contact 16. Further, a movable core 22 connected to a movable core pin 20 is installed inside the base 10. This movable iron core 22 is connected and fixed to a cross bar 26 via a movable buffer rubber 24. This cross bar 26 protrudes toward the arc box 28 fixed to the base 10, and a movable contact 30 is mounted (arranged) at the tip thereof. Further, a movable contact 32 is provided on the movable contact 30 at a position corresponding to the fixed contact 14 . Furthermore, this movable contactor 30
is urged toward the fixed contact 16 by a contact spring 38 between the stopper 34 and the push spring support 36. The arc box 28 includes an arc extinguishing grid 40 made of a magnetic material, and
A commutation plate 42 made of a non-magnetic material is fixed by caulking or the like.

Next, the operation of this conventional electromagnetic contactor will be explained.

When a voltage is applied to the drive unit (not shown), the movable core 22 moves so as to be attracted to the fixed core (not shown). Then, the cross bar 26 connected to this movable iron core 22 and the movable contact 30 disposed on this cross bar 26 also move, and the movable contact 32
The fixed contact 14 comes into contact with the fixed contact 14 to conduct current. Next, when the voltage applied to the drive section is removed, the movable core 22 and the crossbar 26 are operated to return to their original positions by a tripping spring (not shown). At this time, an arc is generated between the movable contact 32 and the fixed contact 14. However, this arc flows from the movable contact 32 to the commutation plate 42.
Then, they are transferred from the fixed contact 14 to the arc runner 18, and further, due to the electromagnetic repulsion between the arc current and the contact current, they are drawn into the grid 40, cooled and separated, and eventually the arc is extinguished.

However, when switching a DC load using an AC electromagnetic contactor as described above, there are the following drawbacks.
The first drawback is that by devising the shapes of the arc runner 18 and the commutation plate 42, the current is reduced to several A to 100 A because it is self-driven using electromagnetic repulsion caused by the arc current and the contact current. The driving force was weak in the small current area nearby, and the arc time was extremely long. A second drawback is that when the circuit voltage increases in the small current range mentioned above, the current does not pass through zero point like in AC, so the interrupting conditions become stricter, and there is a tendency for the circuit to become unable to interrupt, which may lead to a lower rating. It reached a point where I had no choice but to use it.

[Summary of the idea]

The present invention was developed in view of the conventional problems mentioned above, and its purpose is to combine the magnetic blowing effect of a permanent magnet and the arc extinguishing effect of the Day-Ion arc extinguishing method, thereby achieving the advantages of both arc extinguishing methods. The object of the present invention is to provide a compact, inexpensive, high-performance DC electromagnetic contactor that can cut off small to large currents and even high voltages.

In order to achieve the above object, the present invention provides a DC electromagnetic contactor for opening and closing a DC load, in which an arc runner provided on a fixed contact is arranged opposite to the fixed contact with the contacts facing each other. a movable contact, a commutation plate formed of a non-magnetic metal and provided opposite to the back surface of the movable contact and the arc runner, and between the commutation plate and the arc runner; A permanent magnet is provided for each contact pair facing each other and individually fixed to an arc box near the grid by both ends of the commutation plate. .

[Example of idea]

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

The present invention is shown in FIGS. 2 and 3, and the same members as those in FIG.

In the present invention, the barrier parts 44, 46, 4
Permanent magnet 52 whose position is regulated by 8, 50
are individually fixed to the arc box 28 by caulking or other means by means of both ends of a commutation plate 42 made of non-magnetic metal.

Next, the operation will be explained. Due to the operation of the movable iron core 22 explained in the prior art, the movable contact 3
When an arc occurs between the permanent magnet 52 and the fixed contact 14, the generated arc receives the magnetic flux of the permanent magnet 52 at right angles, and is forcibly driven outward (arrow A) according to Fleming's left hand rule. The arc moved by this forced drive is further drawn into the grid 40, where it is cooled, divided, and extinguished. In other words, in a small current range, the arc is extinguished by the driving force of the permanent magnet 52. In addition, in the medium current range, the arc time is reduced by the action of the permanent magnet 52, the contactor current generated by the effective shape of the arc runner 18 and the commutator plate 42, and the driving force due to the electromagnetic repulsion caused by the arc current. The arc is shortened and the arc is extinguished. Furthermore, in a large current range, the arc is quickly drawn into the grid due to the contactor current generated by the effective shape of the arc runner 18 and the commutator plate 42, and the strong driving force due to the electromagnetic repulsion caused by the arc current. It will be cooled, separated, and arc extinguished.

In the above embodiment, only the permanent magnet 52 is provided, but if magnetic pole plates are added to both sides or one side of the contact from both poles (both ends) of the permanent magnet 52, the effective magnetic flux between the contacts due to the permanent magnet 52 will increase. Moreover, it is possible to further improve the interrupting performance.

[Effect of idea]

As explained above, the present invention exhibits excellent interrupting performance for small to medium current ranges due to the magnetic blowing effect of the permanent magnet 52, and for medium to large current ranges, the grid 40, arc Due to the arc extinguishing action by the day ion arc extinguishing method using the runner 18 and the commutator plate 42, the arc is divided by the grid 40 without extending the arc length too much, increasing the arc voltage and increasing the marginal effect as a result. It provides excellent interrupting performance and is equally applicable to small to large current ranges and high voltages. Furthermore, many parts of AC electromagnetic contactors, which are produced in large numbers, can be used, and the number of parts to be attached to the electromagnets can be reduced, so that an inexpensive product can be obtained.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional AC magnetic contactor, Figure 2 is a cross-sectional view of a conventional AC magnetic contactor.
The figure is a sectional view showing one embodiment of the present invention, and FIG. 3 is a structural view showing the inside of the arc box. In each figure, the same members are given the same reference numerals: 16 is a fixed contact, 18 is an arc runner, 30 is a movable contact, 40 is a grid, 42 is a commutation plate, and 52 is a permanent magnet.

Claims (1)

[Scope of utility model registration request] In DC electromagnetic contactors that open and close DC loads,
an arc runner provided on a fixed contact; a movable contact disposed opposite to the fixed contact with contacts facing each other; and a back surface facing the contact of the movable contact and facing the arc runner. a commutation plate made of non-magnetic metal; a grid disposed between the commutation plate and the arc runner; and an arc box near the grid connected to both ends of the commutation plate. 1. A DC electromagnetic contactor comprising: a permanent magnet provided for each pair of contacts facing each other and individually fixed to each other.