JPH0586009B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improvement in an arc extinguishing device for a contact switch, particularly a switch that controls opening and closing of an electric circuit such as an electric motor.

2. Description of the Related Art Opening/closing control of electric circuits of electric motors and the like is normally performed by controlling contact points of electromagnetic contactors or electromagnetic relays. When the contacts open, an arc is generated, which has various adverse effects, so it is desired to improve an arc extinguishing device that quickly extinguishes this arc.

Prior Art Figure 1 shows the configuration of a conventional contact switch (only the right half is shown in cross section because it is symmetrical).
A fixed core 12 is disposed on the mounting base 10, and an operating coil 14 is attached to the fixed core 12. Excitation control of the fixed core is performed by supplying or cutting off excitation current to the operating coil 14. be exposed.

On the other hand, a base substrate 1 formed of a molded product etc.
6 is slidably provided with a cross bar 18, and a movable iron core 20 is fixed to the lower end of this cross bar 18 so as to face the fixed iron core 12.

Further, the cross bar 18 is always urged in the opposite direction to the fixed iron core 12 by a tripping spring (not shown).

Therefore, by supplying or cutting off voltage to the operating coil 14, the fixed core 12 is energized or demagnetized, whereby the movable core 20 is driven toward and away from the fixed core 12, and the crossbar 18 is caused to slide.

2. Description of the Related Art Opening and closing of electric circuits in electric motors and the like is performed by connecting and disconnecting contacts provided in a switch. That is, a fixed contact 22 is fixed to the base substrate 16, and a fixed contact 24 is provided at the tip of the fixed contact 22.

On the other hand, a movable contact 28 is slidably provided on the cross bar 18 by being biased by a pressure spring 26, and a movable contact 30 is provided at the tip of the movable contact 28, facing the fixed contact 24. is provided.

Therefore, as described above, as the crossbar 18 slides, the movable contact 30 connects and disconnects from the fixed contact 24, thereby controlling the opening and closing of the electric circuit. That is, if the right side of FIG. 1 is the IN side, the electric circuit is opened and closed by the sliding of the movable contact 28, and the opening and closing control between the IN side fixed contact 22 and the OUT side fixed contact (not shown) is performed. line is done.

When the fixed and movable contacts 24 and 30 open, an arc 100 is generated, and this arc 100 connects both contacts 2.
4,30, causing negative effects such as wear and tear. In order to eliminate such problems, a metal grid 32 is provided near the contacts 24 and 30, as shown in FIG.
6 and is insulated from the outside, and the arc 100 generated between the contacts is commutated to the grid 32 to extinguish the arc.

That is, the arc 100 generated when both contacts 24 and 30 are opened is attracted to the grid 32 and curved toward the grid 32 (102). This bending and expansion of the arc increases the arc voltage, causing dielectric breakdown between the movable contact 30 and the grid 32, and commutating the arc to the grid (104). This commutated arc causes dielectric breakdown between the lower end of the grid 32 and the fixed contact 22, causing the fixed contact 22 to break down.
2 (106), and the arc extinguishing action is completed.

In addition, both the contacts 24 and 30 and the grid 32
is the arc box 3 attached to the base board 16.
4 isolates it from the outside and prevents dust etc. from entering from the outside.

However, in this type of device, as shown in FIG. Since the area of the wall end surface 33 is small and sharp, there is a disadvantage that the wall end surface 33 is damaged by wear and tear during arc-extinguishing discharge, shortening the life of the grid. This has the disadvantage that it is difficult to generate discharge from the movable contact 30 to the fixed contact 22, and therefore it is difficult to quickly extinguish the arc commutated from the movable contact 30 to the grid.

OBJECT OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a contact switch that can extremely quickly extinguish the arc that occurs when both contacts open and commutates to the grid. Our goal is to provide the following.

Structure of the Invention In order to achieve the above object, the present invention provides a movable contact having a first movable contact and a second movable contact, and a first movable contact having a fixed contact that comes into contact with and separates from the first movable contact. a fixed contact; a second fixed contact having a fixed contact that comes into contact with and separates from the second movable contact;
A first grid that is provided opposite to the first movable contact and the first fixed contact and extinguishes an arc generated when the movable contact and the fixed contact are opened, a flat plate portion facing at least one end portion and commutating the arc from the movable contact;
a first grid having a substantially U-shaped protrusion that faces the first fixed contact and diverts an arc to the fixed contact; and a first grid that extinguishes an arc generated when the movable contact and the fixed contact are separated. a second grid that faces at least one end of the movable contact and commutates the arc from the movable contact;
A second grid electrically insulated from the first grid, the second grid having a substantially U-shaped protrusion that faces the second fixed contact and commutates the arc to the fixed contact.
It is characterized by having a grid of.

Embodiment FIG. 4 shows the configuration of a grid of a contact switch according to the present invention, and the same members as in the conventional device are given the same reference numerals and their explanations will be omitted. Therefore, as shown in the conventional device, a movable contact, a fixed contact, a grid, etc. are provided symmetrically on the IN side and the OUT side, and both grids are insulated from each other. The grid part will be explained in detail below.

As mentioned above, the characteristic feature of the present invention is that the insulated grid is configured in a unique shape,
The structure is such that the arc commutated from the movable contact to the grid can be extinguished extremely quickly.

In this embodiment, a U-shaped protrusion 38 is formed by bending the lower end of the flat plate part 36 of the grid 32 outward, and the tip of this protrusion faces the fixed contact 22 with a gap in between. ing.

In this embodiment, the shape of the protrusion 38 was determined based on the results of a preliminary experiment conducted to determine the ability to interrupt the arc commutated from the movable contact 30 to the grid 32.

That is, FIG. 5 shows the experimental results of various electrode shapes and the breaking currents corresponding to these electrode shapes. In this experiment, a fuse was connected between electrodes of different shapes, and a fusing current was applied to the electrodes to blow the fuse. As the fuse melted, an arc was generated between the two electrodes. The maximum breaking current is determined by measuring the time for which the arc is extinguished and when the arc extinguishing time is 0.5 seconds or less.

According to the experimental results, the current value that can be interrupted is small when the tips of the electrodes are needle-shaped and sharpened, whereas the current interrupting ability is increased by making the tips of both electrodes curved. I can understand what is going on. This current interrupting ability corresponds to the arc extinguishing ability, and as a result, it is possible to increase the arc extinguishing ability by making the arc extinguishing part of the grid into a curved shape, which allows commutation to the grid 32. It is possible to quickly extinguish arcs caused by

In this embodiment, the arc-extinguishing portion of the grid is formed into a U-shape based on the above-mentioned experimental results.

That is, the fixed contact 22 is formed into a flat plate shape, and the protrusion 38 of the grid 32 facing the fixed contact 22 at a predetermined distance is formed into a U-shaped curved surface. As can be understood from the experimental results, the ability to extinguish the arc is enhanced, and as a result, the extinguishing of the arc from the protrusion 38 to the fixed contact 22 is achieved quickly. In other words, since the IN side grid and the OUT side grid are insulated, if an arc generated on the IN side and OUT side is commutated from the movable contacts on the IN side and OUT side to the respective grids, the arc flows into the fixed contact through the grid,
The arc is divided into two: an arc between the movable contact and the grit, and an arc between the grit and the fixed contact. At this time, the number of places where the broken arc comes into contact with the metal part of the grid increases, so the arc is efficiently cooled, the arc is quickly extinguished, and the interrupting performance is improved.

Further, as described above, since the protrusion 38 is formed in a U-shape, when arc-extinguishing discharge is performed from the protrusion 38 to the fixed contact 22, the protrusion 38
There is almost no phenomenon of wear and tear on the grid 32, and therefore it is possible to extend the life of the grid 32.

Effects of the Invention As explained above, according to the present invention, an arc generated when a contact is opened is diverted to a grid having a U-shaped protrusion at the end and insulated from the outside. , it is possible to quickly extinguish the arc from the grid to the fixed contact.

In addition, there is almost no wear and tear on the grid during arc-extinguishing discharge from the grid to the fixed contact, and it is therefore possible to extend the life of the grid.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing a conventional contact switch;
The figures are a configuration diagram showing the grid of the device shown in FIG. 1, FIG. 3 is an explanatory diagram showing the arc extinguishing behavior in the grid of the conventional device, and FIG. 4 is a configuration diagram showing the grid of the contact switch according to the present invention. Figure 5 is a characteristic diagram showing the relationship between the electrode shape and breaking current, which was created to design the shape of the arc extinguishing part of the grid, and Figures 6 and 7 show the arc extinguishing behavior of the device of the present invention. FIG. The same members in each figure are given the same reference numerals, 22 is a fixed contact, 24 is a fixed contact, 28 is a movable contact,
30 is a movable contact, 32 is a grid, and 38 is a protrusion.

Claims (1)

[Claims] 1 A movable contact having a first movable contact and a second movable contact, a first fixed contact having a fixed contact that makes contact with and separates from the first movable contact, and a movable contact that makes contact with the second movable contact. A second fixed contact having a fixed contact to be separated is provided opposite to the first movable contact and the first fixed contact, and extinguishes an arc generated when the movable contact and the fixed contact are opened. a first grid comprising: a flat plate portion facing at least one end of the movable contact and commutating the arc from the movable contact; and a flat plate portion facing the first fixed contact and commutating the arc to the fixed contact; a first grid having a substantially U-shaped protrusion for commutating current; and a second grid for extinguishing an arc generated when a movable contact and a fixed contact are opened, the second grid having a substantially U-shaped protrusion that commutates the current, a flat plate portion that faces the end portion and commutates the arc from the movable contact; and a substantially U-shaped protrusion that faces the second fixed contact and commutates the arc to the fixed contact; A contact switch comprising: a second grid electrically insulated from the first grid.