Circuit breaker arc extinguishing chamber unit

Abstract

To reliably hold a grid by an arc extinguishing plate without deforming the arc extinguishing plate.SOLUTION: A grid 2 is provided with locking pieces 21 to be locked to an arc extinguishing plate 3 on the left and right, and the locking piece 21 is provided with a step portion 4 whose tip is widened with respect to the base and to be locked to the arc extinguishing plate 3 in the middle. the arc extinguishing plate 3 is provided with an insertion hole 31a into which the locking piece 21 is inserted. The insertion hole 31a is composed of a through hole 5 and a tongue piece 6 formed adjacent to the through hole 5, and the tongue piece 6 is elastically deformed to expand the through hole 5. The width W1 of the through hole 5 is narrower than the width W2 of the tip of the locking piece 21, the width D1 of the insertion hole 31a is wider than the width W2, and the width W1 of the base of the locking piece 21 is slightly smaller than the width D2 of the opening. Due to elastic deformation of the tongue piece 6, the locking piece 21 can be inserted into the insertion hole 31a, and when the insertion of the locking piece 21 is completed, the tongue piece 6 elastically returns and the step portion 4 engages with the arc extinguishing plate 3.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an arc extinguishing chamber unit for a circuit breaker that extinguishes an arc that occurs between contacts when breaking a circuit. [Background technology]

[0002] 2. Description of the Related Art Circuit breakers such as DC breakers are provided with an arc-extinguishing chamber for extinguishing an arc that occurs when an electric circuit is interrupted, and contacts are arranged within the arc-extinguishing chamber. The arc-extinguishing chamber is configured by arranging multiple grids inside surrounded by arc-extinguishing plates. For example, in Patent Document 1, arc-extinguishing plates are arranged facing each other on the left and right, and multiple plate-shaped grids are arranged so that they overlap one another vertically between them. In addition, the left and right sides of the grids are held by the arc-extinguishing plates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-33890 Summary of the Invention [Problem to be solved by the invention]

[0004] As disclosed in Patent Document 1, the grid is integrated by inserting and locking pieces provided on the left and right ends into holes in the arc-extinguishing plate. In this conventional locking structure, the grid's locking pieces are inserted into the holes in the arc-extinguishing plate, and then the grid is securely locked and held in place by deforming it, such as by crimping. However, because the grid is made of metal and the arc-extinguishing plate is made of resin, the arc-extinguishing plate is easily deformed by the caulking action of the grid, making it impossible to apply strong caulking, and the locking effect is sometimes weak.In this case, the connection between the grid and the arc-extinguishing plate may come loose due to the pressure of the arc gas generated during interruption.

[0005] In view of the above problems, the present invention aims to provide an arc-extinguishing chamber unit for a circuit breaker that can reliably hold a grid on an arc-extinguishing plate without deforming the arc-extinguishing plate. [Means for solving the problem]

[0006] In order to solve the above problem, the invention of claim 1 provides an arc-extinguishing chamber unit for a circuit breaker in which a plurality of plate-shaped grids are arranged one above the other and are held by arc-extinguishing plates arranged on the left and right, the grids having locking pieces protruding on the left and right to lock onto the arc-extinguishing plates, the locking pieces having tips that are wider than the base and equipped with steps midway for locking onto the arc-extinguishing plates, while the arc-extinguishing plates are provided with insertion holes for inserting the locking pieces to hold the grids, the insertion holes comprising through holes and tongue pieces formed adjacent to the through holes, the through holes being configured so that the through holes are expanded by elastic deformation of the tongue pieces, and the width of the base of the locking pieces is formed to be the same as or slightly smaller than the width of the through holes. With this configuration, the tongue of the locking piece inserted into the insertion hole elastically returns to its original shape, and the stepped portion locks onto the arc-extinguishing plate. This means that the grid is held in place by the arc-extinguishing plate without coming loose. This eliminates the need to caulk the locking piece, and prevents deformation of the arc-extinguishing plate.

[0007] In the above configuration, the arc extinguishing plate may have a back surface connecting the side surfaces in addition to the left and right side surfaces provided with insertion holes, and the entire arc extinguishing plate may be formed in a U-shape with an open front end where the contacts of the circuit breaker are inserted. By adopting this configuration, the side sections are connected via the back section, making it easy to handle and attach the grid. In addition, the arc extinguishing plate closes off three sides of the arc extinguishing chamber, preventing the arc from spreading.

[0008] In addition, in the above configuration, it is also possible to adopt a configuration in which the step portion of the locking piece is formed by providing a protrusion at the tip of the locking piece that protrudes forward or backward toward the direction in which the contact of the circuit breaker is inserted, and the tongue piece is positioned on the side of the locking piece that does not have the protrusion. By adopting this configuration, the locking piece inserted into the insertion hole is reliably locked at the stepped portion to a sturdy portion of the arc-extinguishing plate by the action of the resiliently returning tongue piece, so that the locked state will not come loose.

[0009] In the above-mentioned configuration, it is also possible to adopt a configuration in which recesses are provided at both ends of the rising portions of the locking pieces of the grid, the recesses being cut out inward toward the inside of the grid. By adopting this configuration, a recess is provided in the rising portion of the grid's locking piece, so even if burrs are generated in the rising portion of the locking piece during the grid manufacturing process, the presence of the recess prevents the rising portion from widening, thereby maintaining good locking action between the locking piece and the arc extinguishing plate. [Effects of the Invention]

[0010] According to the present invention, when the locking piece is inserted into the insertion hole, the tongue piece that was deformed during insertion elastically returns to its original position, and the stepped portion locks onto the arc-extinguishing plate. Therefore, the grid is held by the arc-extinguishing plate without coming out. Therefore, there is no need to caulk the locking piece, and the arc-extinguishing plate is not deformed. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a perspective view showing an example of an arc extinguishing chamber unit of the circuit breaker according to the present invention. [Figure 2] FIG. [Figure 3] FIG. 2 is an enlarged view of part A in FIG. [Figure 4] FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line BB in FIG. 4. [Figure 6] FIG. 10 is an explanatory diagram showing a state in which the grid is being held by the arc-extinguishing plate. DETAILED DESCRIPTION OF THE INVENTION

[0012]

[0016] The present invention will be described in detail below with reference to the accompanying drawings, in which:

[0017] Fig. 1 is a perspective view showing an example of an arc-extinguishing chamber unit of a circuit breaker according to the present invention;

[0018] The arc-extinguishing chamber unit 1 is composed of a plurality of grids 2 arranged so as to be stacked in the vertical direction, and an arc-extinguishing plate 3 that holds and fixes the grids 2.

[0013] Fig. 2 is a perspective view of the grid 2. The grid 2 is formed by punching out a metal plate, and as shown in Fig. 2, locking pieces 21 protrude from the left and right sides for connection to the arc-extinguishing plates 3. The locking pieces 21 are provided in four locations, at the front and back. The front side of the grid 2 is formed with a contact arrangement section 22 that is largely cut out to accommodate the contacts of a circuit breaker (not shown), and the entire grid is roughly U-shaped. The tip of the locking piece 21 has a claw portion 21a that protrudes so as to be bent forward and is formed in an L shape. A step portion 4 formed by this claw portion 21a locks onto the arc-extinguishing plate 3, providing a retaining effect. In addition, the rising portion of the locking piece 21 has recesses 23 cut out toward the inside of the grid 2 on both the front and rear sides.

[0014] The arc extinguishing plate 3 is made of synthetic resin containing glass fiber that has excellent insulating properties and arc resistance, and has side portions 31 arranged on the left and right of the grid 2, and a back portion 32 that connects the side portions. The arc extinguishing plate 3 is formed by punching out a single plate and bending it into a U shape. The side surface portion 31 is provided with a plurality of insertion holes 31a for inserting the locking pieces 21 of the grid 2 to hold the grid 2. The rear surface portion 32 is provided with a plurality of holes 32a for venting arc gas generated when the contacts are broken. The contacts of the circuit breaker (not shown) are inserted from the open front (left side in FIG. 1) and open and close in the vertical direction.

[0015] The relationship between the locking piece 21 and the insertion hole 31a will be described below with reference to Figures 3 to 5. Figure 3 is an enlarged view of part A in Figure 1, where the grid 2 is indicated by a two-dot chain line. Figure 4 is a side view of the arc-extinguishing unit 1, and Figure 5 is a cross-sectional view taken along line BB in Figure 4. The insertion hole 31a is made up of two parts, a through hole 5 and a tongue piece 6. The entire insertion hole 31a is formed long in the front-rear direction, and its height is formed slightly higher than the thickness of the grid 2. The through hole 5 is located on the front side of the insertion hole 31a, i.e., on the contact insertion side, and the tongue 6 is located on the rear side. As shown in Fig. 5, the width D2 of the through hole 5 is formed slightly wider than the width W1 of the rising portion of the locking piece 21. Furthermore, the width D1 of the entire insertion hole 31a including the tongue 21a is formed sufficiently wider than the width W2 of the tip of the locking piece 21. Specifically, the tongue 6 is formed so that it can be elastically deformed to allow the widened tip of the locking piece 21 to be inserted therethrough.

[0016] FIG. 6 is an explanatory diagram showing the state in the middle of holding the grid 2 to the arc-extinguishing plate 3. As shown in FIG. 6, the tongue 6 is deformed and the locking piece 21 is inserted. The insertion is performed simultaneously for all grids 2 arranged in a stack, with the grids 2 being inserted one side at a time. Once insertion is complete, the deformed tongue 6 elastically returns to the state shown in FIG. 5. In this way, once insertion is complete, the locking piece 21 is prevented from moving back and forth. At the same time, the step 4 of the locking piece 21 locks into the end of the insertion hole 31a of the arc-extinguishing plate 1. As a result, the locking piece 21 that has been completely inserted into the insertion hole 31 a has its step portion 4 locked to the arc-extinguishing plate 3 , preventing the grid 2 from coming off, and the grid 2 is held by the locking plate 3 .

[0017] In this way, the locking piece 21 inserted into the insertion hole 31a has its step portion 4 locked onto the arc-extinguishing plate 3 as the tongue piece 6, which was deformed during insertion, elastically returns to its original shape. Therefore, the grid 2 is held on the arc-extinguishing plate without coming out. In particular, the locking piece 21 inserted into the insertion hole 31a has its step portion 4 securely locked onto a sturdy portion of the arc-extinguishing plate 3 by the action of the elastically returned tongue piece 6, so the locked state will not come loose. Therefore, there is no need to caulk the locking piece 21, and the arc-extinguishing plate 3 will not deform. Furthermore, since the side portions 31 are connected to each other via the back portion 32, the arc-extinguishing plate 3 is easy to handle and the grid 2 can be easily attached. Furthermore, since the arc-extinguishing chamber is closed on three sides by the arc-extinguishing plate 3, the arc can be prevented from spreading. Furthermore, since a recess 23 is provided at the rising portion of the locking piece 21 of the grid 2, even if burrs are generated at the rising portion of the locking piece during the manufacturing process of the grid 2, the presence of the recess 23 can prevent the rising portion from widening, and good locking action between the locking piece 21 and the arc extinguishing plate 3 can be maintained.

[0018] In the above embodiment, the arc extinguishing plate 3 is bent into a U-shape and the left and right side portions 31 are connected via the back portion 32, but the back portion 32 may not be provided and the plate may be separated into two left and right members. Furthermore, although the claws 21a provided on the locking pieces 21 of the grid 2 protrude forward, they may also protrude rearward, in which case the arrangement of the through holes 5 and the tongues 6 may be reversed, with the tongues 6 positioned at the front and the through holes 5 positioned at the rear, thereby enabling the claws 21a to be securely locked to the arc-extinguishing plate 3. Furthermore, although the claws 21a are provided on only one side, they may also be provided on both ends of the locking pieces 21, with steps provided on the tongue 6 side in addition to the end of the through holes 5. [Explanation of symbols]

[0019] 1··Arc extinguishing chamber unit, 2··Grid, 3··Arc extinguishing plate, 4··Recessed portion, 5··Through hole, 6··Tongue, 21··Latching piece, 21a··Pawl, 22··Contact arrangement portion, 23··Recessed portion, 31··Side plate, 31a··Insertion hole, 32··Rear plate.

Claims

[Claim 1] In an arc extinguishing chamber unit of a circuit breaker, a plurality of plate-shaped grids are arranged so as to be stacked one on top of the other, and the grids are held by arc extinguishing plates arranged on the left and right, The grid has locking pieces protruding on the left and right sides to be locked to the arc extinguishing plate, The locking piece has a tip end that is wider than a base end and has a step portion in the middle that locks onto the arc-extinguishing plate, the arc extinguishing plate is provided with an insertion hole into which the locking piece is inserted to hold the grid, The insertion hole is configured to include a through hole and a tongue piece formed adjacent to the through hole, and the through hole is expanded by elastic deformation of the tongue piece, 10. An arc extinguishing chamber unit for a circuit breaker, wherein the width of the base of said locking piece is the same as or slightly smaller than the width of said through hole.

Images