JP2011228173A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easy-to-manufacture circuit breaker with an arc-extinguishing device which can be installed even in a non-rectangular space according to the shape of the space.SOLUTION: A contact part 3 is disposed in an arc-extinguishing chamber 5 in which an arc-extinguishing device 15 for extinguishing arc generated between contacts 11a and 12a is installed. The arc-extinguishing device 15 is formed of two metal grids 17a and 17c which limit and interrupt generated arc, and a pair of arc-extinguishing plates 16 and 16 having a grid holding part 16b which holds the right and left sides of the metal grids 17a and 17c and a protection wall 16a covering the right and left sides of a movement space in which the movable contact 12a performs make-break operation. The arc-extinguishing plates 16 are formed of nylon 6.

Description

  The present invention relates to a circuit breaker that cuts off an electric circuit when an electric circuit abnormality such as an overcurrent occurs, and more particularly, to a circuit breaker in which an arc extinguishing device is provided in an arc extinguishing chamber in which a contact portion that performs an interruption operation is arranged.

The circuit breaker breaks the electric circuit when an abnormal current such as an overcurrent flows in the electric circuit, but at this time, arc discharge occurs between the contacts. Since this arc discharge adversely affects the contact and the surroundings, the contact is surrounded by an arc extinguishing chamber, and an arc extinguishing device is installed to extinguish the arc in a short time.
Arc extinguishing devices are widely used with a structure in which a grid is assembled to an arc extinguishing plate, and the arc extinguishing plate is formed by bending a plate member excellent in arc resistance and insulation into a U shape, or left and right Are arranged separately, and a plurality of grids formed of metal plates are stacked inside and connected to the arc extinguishing plate. Providing such an arc extinguishing device adjacent to the contact enables quick arc extinguishing (see, for example, Patent Document 1).

JP 2007-115540 A

However, since arc extinguishing plates are made of, for example, vulcanized fibers having excellent insulation resistance, it is difficult to increase dimensional accuracy and the shape cannot be complicated. Therefore, the shape of the arc extinguishing chamber is limited, which is an obstacle to the optimal arrangement of the circuit breaker components and the circuit breaker downsizing.
In addition, since the grid is inserted into the mounting groove formed in the arc extinguishing plate and both left and right ends are crimped and fixed after insertion, the grid is troublesome to mount and the cost is high.

  Therefore, in view of such problems, the present invention has an object to provide a circuit breaker including an arc extinguishing device that is easy to manufacture and can be assembled in accordance with a space shape even if it is not a rectangular space. It is said.

In order to solve the above-mentioned problems, the invention of claim 1 is provided with a contact portion composed of a fixed contact and a movable contact on an electric circuit disposed between a power supply side terminal and a load side terminal. In the circuit breaker that opens the contact portion to interrupt the electric circuit when an abnormal current flows, an arc extinguishing device is assembled in the arc extinguishing chamber in which the contact portion is disposed, and the arc extinguishing device is generated. Grid holding up to at least one metal grid for current-cutting the arc, a grid holding part for holding the metal grid, and a part covering the left and right sides of the moving space where the movable contact opens and closes And a pair of arc-extinguishing plates made of a synthetic resin having a protective wall extending from the portion.
According to this configuration, since the arc extinguishing plate is formed of synthetic resin, it can be easily formed into a desired shape, and post-processing such as bending is not necessary. In addition, since the metal grid can be held and fixed, a subsequent process such as caulking can be eliminated, and the metal grid can be manufactured at a low cost. Furthermore, since the arc extinguishing plate is disposed so as to surround the contact portion by providing a protective wall, the circuit breaker case can be protected from an arc generated when the electric circuit is interrupted, and the degree of freedom in selecting the material of the circuit breaker case is increased.

According to a second aspect of the present invention, in the configuration according to the first aspect, the pair of arc-extinguishing plates are connected by connecting means, and the connecting means is a grid made of a synthetic resin arranged in parallel with the metal grid. It is characterized by.
According to this configuration, the left and right arc extinguishing plates are connected and formed integrally, so that assembly work is easy. And since a connection means is the grid made from a synthetic resin arranged in parallel with the metal grid, it can also contribute to arc extinction.

A third aspect of the invention is characterized in that, in the configuration of the first or second aspect, the arc-extinguishing plate is made of a synthetic resin mainly composed of nylon and reinforced by glass fibers.
According to this configuration, by using a synthetic resin reinforced with glass fiber for the arc extinguishing plate, the arc resistance and the insulation can be improved, and the circuit breaker case is made of a highly insulating material. No need to limit. Therefore, it becomes possible to produce the circuit breaker case with an inexpensive synthetic resin that is easy to mold.

According to the present invention, since the arc extinguishing plate is made of synthetic resin, it can be easily formed into a desired shape, and post-processing such as bending is not necessary. In addition, since the metal grid can be formed into a shape that can be easily held, subsequent processes such as caulking can be eliminated, and the metal grid can be manufactured at a low cost.
Furthermore, since the arc extinguishing plate is disposed so as to surround the contact portion by providing a protective wall, the circuit breaker case can be protected from an arc generated when the electric circuit is interrupted, and the degree of freedom in selecting the material of the circuit breaker case is increased.

It is side surface explanatory drawing which showed an example of the circuit breaker which concerns on this invention, and removed a part of case. It is an enlarged view of the arc-extinguishing apparatus of FIG. 1, (a) is a side view, (b) is a front view, (c) is a top view. It is a perspective view of an arc extinguishing apparatus, (a) has shown the state which isolate | separated the metal grid, (b) has shown the state which assembled | attached the metal grid.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view showing an example of a circuit breaker according to the present invention, in which a side cover of a circuit breaker case is removed and the inside is exposed. 1 is a power supply side terminal, 2 is a load side terminal, 3 is a contact portion having a fixed contact 11a and a movable contact 12a, 4 is an operation handle for turning on / off the contact portion 3, and 5 is to surround the contact portion 3. The formed arc extinguishing chamber, 6 is a shut-off mechanism that performs a trip operation when an electric circuit abnormality such as overcurrent occurs, 7 is a bimetal piece for detecting overcurrent, and 8 is an electromagnetic for detecting short circuit current These devices are both assembled in the circuit breaker case 10. In the following description, the left side of the drawing in which the power supply side terminal 1 is provided in FIG.
The circuit breaker case 10 is provided with a separation wall in the center and two electric circuits are divided into left and right, and the power source side terminal 1, the load side terminal 2, the contact portion 3, the arc extinguishing chamber 5, etc., respectively. A pair is installed.

  The fixed contact 11 a is provided on the fixed contact 11 extending from the power supply side terminal 1, and the movable contact 12 a is provided on the movable contact 12 connected to the load side terminal 2. As shown in FIG. 1, the fixed contact 11 and the movable contact 12 are arranged in the vertical direction, and the fixed contact 11a and the movable contact 12a are arranged at the upper end portion thereof. Further, a bimetal piece 7 and an electromagnetic device 8 are provided on the electric path between the movable contact 12 and the load side terminal 2, and an arc extinguishing device 15 is provided above the arc extinguishing chamber 5.

  2 and 3 show the arc extinguishing device 15, FIG. 2 (a) is an enlarged side view of the arc extinguishing device 15 of FIG. 1, FIG. 2 (b) is a front view, and FIG. 2 (c) is a plan view. FIG. 3A is a perspective view with the metal member removed, and FIG. 3B is a perspective view with the metal member assembled. As shown in FIGS. 2 and 3, the arc extinguishing device 15 includes arc extinguishing plates 16 and 16 arranged in parallel so as to cover the left and right wall surfaces of the arc extinguishing chamber 5, and the two arc extinguishing plates 16 and 16. A grid 17 (a first grid 17a, a second grid 17b, and a third grid 17c) spanned between them is provided.

The arc extinguishing plate 16 is made of a synthetic resin excellent in insulation and arc resistance, for example, 6 nylon (PA6) to which about 30% of glass fiber is added as a filler, and is arranged so as to cover the left and right sides of the contact portion 3. A protection plate 16a extends downward, and a grid holding portion 16b is formed with a grid 17 disposed on the top. The grid holding part 16b is continuously formed on the protection plate 16a.
The left and right arc extinguishing plates 16 and 16 are connected at their lower ends by a connecting piece 16c and at the top by a second grid 17b provided at the approximate center of the grid holding portion 16b. The second grid 17b is a resin grid and is formed integrally with the left and right arc extinguishing plates 16 and 16.

  The protection plate 16a has a depth W that matches the amount of movement of the movable contact 12a, and is formed to protect the left and right wall surfaces of the arc extinguishing chamber 5 from the generated arc. The grid holding portion 16b is formed with a slit-like holding groove 20 that holds the first and third grids 17a and 17c. The holding groove 20 is formed in parallel to the vertical direction together with the second grid 17b at the center.

The first and third grids 17a and 17c are made of a magnetic metal and are substantially square plate members as shown in FIG. 3, and the engaging pieces 21 that engage with the holding grooves 20 protrude from the left and right sides. It is installed.
When the arc extinguishing device 15 is installed in the arc extinguishing chamber 5, the first grid 17a is assembled at a position where the lower end is disposed in the vicinity of the fixed contact 11a, and the third grid 17c is movable with the end dissociated. It is assembled at a position arranged in the vicinity of the contact 12a.
The first and third grids 17a and 17c assembled in this way are provided with the arc extinguishing device 15 in the arc extinguishing chamber 5, so that the rear end of the upper grid comes into contact with the arc extinguishing chamber forming surface of the circuit breaker case 10, The assembled state is maintained without falling out.

Thus, since the arc-extinguishing plate 16 is formed of synthetic resin, it can be easily formed into a required shape, and the left and right arc-extinguishing plates 16 and 16 can be connected without post-processing such as bending. It is easy to assemble the grid. In addition, since the metal first and third grids 17a and 17c can be held and fixed, it is possible to eliminate a subsequent process such as caulking and to manufacture the grid at a low cost.
Further, since the arc extinguishing plate 16 is disposed so as to surround the contact portion 3 by providing the protective wall 16a, the circuit breaker case 10 can be protected from an arc generated when the electric circuit is interrupted, and the material selection of the circuit breaker case 10 can be made. Increases freedom.
Further, the left and right arc extinguishing plates 16 are connected by the connecting piece 16c and the second grid 17b and are formed integrally, so that the assembling work is easy. And it can contribute also to arc extinction by making a connection means into the 2nd grid 17b arranged in parallel with the metal 1st and 3rd grids 17a and 17c.
In addition, by using a specific synthetic resin, the arc extinguishing plate 16 can have good arc resistance and insulation, and it is not necessary to limit the material of the circuit breaker case 10 to a highly insulating material. It can be made of an easy and inexpensive synthetic resin.

In the above embodiment, the two arc extinguishing plates 16 of the arc extinguishing device 15 are connected at two locations by the connecting piece 16c and the second grid 17b, but only the connecting piece 16c or only the second grid 17b is connected. You may connect in one place. Moreover, although the two metal grids of the first and third grids 17a and 17c are assembled, the number of the grids may be one, or three or more.
Further, the material of the arc extinguishing plate 16 is a glass fiber reinforced resin mainly composed of 6 nylon, but may be a resin mainly composed of 46 nylon.

  1 .... Power supply side terminal 2 .... Load side terminal 3 .... Contact part 5 .... Arc extinguishing chamber 10 .... Circuit breaker case 11 .... Fixed contact 11a ... Fixed contact 12 .... Movable contact, 12a ... movable contact, 15 .... arc extinguishing device, 16 .... arc extinguishing plate, 16a ... protective wall, 16b ... grid holding part, 16c ... connecting piece, 17a ... first grid ( Metal grid), 17b ... second grid (synthetic resin grid), 17c ... third grid (metal grid).

Claims (3)

A contact part composed of a fixed contact and a movable contact is provided on the electric circuit arranged between the power supply side terminal and the load side terminal, and when an abnormal current such as an overcurrent flows in the electric circuit, the contact part is opened to operate the electric circuit. In circuit breakers that shut off
An arc extinguishing device is assembled in the arc extinguishing chamber in which the contact portion is disposed, and the arc extinguishing device holds at least one metal grid for current-limiting and interrupting the generated arc and the metal grid. A grid holding part, and a pair of arc-extinguishing plates made of a synthetic resin having a protective wall extending from the grid holding part to a portion covering the left and right side parts with respect to a moving space in which the movable contact opens and closes. A circuit breaker characterized by that. 2. The circuit breaker according to claim 1, wherein the pair of arc extinguishing plates are connected by connecting means, and the connecting means is a synthetic resin grid arranged in parallel with the metal grid. 3. The circuit breaker according to claim 1, wherein the arc extinguishing plate is made of a synthetic resin mainly composed of nylon and reinforced with glass fiber.

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