Circuit interrupter of circuit breaker and assembling method of the circuit interrupter

Abstract

To improving assemblability of a circuit breaker so as to eliminate a risk of a protection plate being blown off from a back surface wall of an arc-extinguishing chamber unit even if a gas pressure of the arc-extinguishing chamber rises.SOLUTION: An arc-extinguishing device 7 of a circuit breaker 1, includes: an arc-extinguishing chamber unit 16 that is arranged in a case 2, and surrounds a stationary contact 10 and a movable contact 11; and a protection plate 20 that is arranged on a back surface wall so as to cover an exhaust port 33 that is open in one side 32a of a longitudinal direction of a back surface wall 32 of the arc-extinguishing chamber unit. The protection plate comprises: a long main body part 21 that covers the exhaust port; and a base part 22 (a pair of first engagement pieces 24a and 24b, a penetration hole 25, and a second engagement piece 27) that is formed continuously to one end of the longitudinal direction of the main body part. The other side in the longitudinal direction of the back surface wall of the arc-extinguishing chamber unit 16 is provided with protection plate holding parts 35a, 35b, and 36a onto which the protection plate is integrally mounted, restricting the protection plate from departing from the back surface wall of the base part, and restricting the protection plate from moving toward one side and the other side in the longitudinal direction of the back surface wall of the base part.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an arc-extinguishing device for a circuit breaker and a method for assembling the arc-extinguishing device, and more particularly to an arc-extinguishing device in which a protective plate covering an exhaust port opening in the rear wall of an arc-extinguishing chamber unit is attached integrally to the arc-extinguishing chamber unit. [Background technology]

[0002] Circuit breakers are equipped with an arc extinguishing device that extinguishes an arc that occurs when a large current is interrupted (for example, Patent Document 1). An exhaust port that exhausts arc gas to the outside is opened on the rear wall of the arc extinguishing device, and the exhaust port is covered with a protective plate to prevent dust and foreign objects from entering the inside of the arc extinguishing device from the outside under normal conditions.

[0003] The protective plate of Patent Document 1 is attached to cover the exhaust port of the arc extinguishing device by sandwiching and fixing the base between the support of the arc extinguishing device and a fixed contact arranged in the case. In this way, Patent Document 1 has a problem in terms of workability in assembling the circuit breaker, since the protective plate, which is a thin and small part, must be attached to cover the exhaust port of the arc extinguishing device during assembly of the circuit breaker.

[0004] Therefore, it is conceivable to use double-sided tape to attach the protective plate integrally to the rear wall of the arc-extinguishing device, thereby forming the protective plate into a unit with the arc-extinguishing device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2022-121258 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when attaching a protective plate to the rear wall of the arc extinguishing device using double-sided tape, post-processing work is required for the tape cover that is peeled off. In addition, the adhesive strength of the double-sided tape decreases when it comes into contact with the arc gas, and there is a risk that the protective plate will fall off from the rear wall of the arc extinguishing device.

[0007] Therefore, the present invention aims to provide an arc-extinguishing device for a circuit breaker that can improve the ease of assembly of the circuit breaker and that does not have the risk of the protective plate being blown off from the rear wall of the arc-extinguishing chamber unit even if the gas pressure in the arc-extinguishing chamber increases. Another object of the present invention is to provide a method for assembling the arc-extinguishing device that can be automated using an automatic machine. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, one embodiment of the present invention provides an arc-extinguishing device for a circuit breaker having an arc-extinguishing chamber unit arranged inside a case and surrounding a fixed contact and a movable contact, and a protective plate arranged on the rear wall of the arc-extinguishing chamber unit so as to cover an exhaust port provided on the rear wall, wherein the protective plate has a main body portion covering the exhaust port and a base portion formed on one end of the main body portion, and the rear wall of the arc-extinguishing chamber unit is provided with a protective plate holding portion which prevents the base from coming off the rear wall and also prevents the base from moving from the rear wall, thereby attaching the protective plate integrally.

[0009] In addition, a method of assembling an arc-extinguishing device according to one embodiment of the present invention includes the steps of: moving the protective plate toward the rear wall of the arc-extinguishing chamber unit and placing the protective plate on the rear wall so that a pair of first engaging pieces of the base are positioned on the other longitudinal side of the rear wall relative to the pair of hook portions of the protective plate holding portion and the through hole of the base is positioned on the other longitudinal side of the rear wall relative to the second retaining protrusions of the protective plate holding portion; and sliding the protective plate to one longitudinal side of the rear wall, inserting the pair of first engaging pieces into the pair of hook portions and causing the second retaining protrusions to enter the through holes so that the second engaging pieces press against the side walls of the second retaining protrusions. Effect of the Invention

[0010] The arc extinguishing device for a circuit breaker according to the present invention can improve the assembly of the circuit breaker and can reliably prevent the protective plate from being blown off from the rear wall of the arc extinguishing chamber unit even if the gas pressure in the arc extinguishing chamber increases.

[0011] Furthermore, according to the method for assembling the arc extinguishing device of the present invention, the assembly can be automated using an automatic machine. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing a configuration of a circuit breaker according to the present invention. [Diagram 2] 1 is a perspective view showing an arc extinguishing device in which a protective plate mounted on a circuit breaker is integrally attached to an arc extinguishing chamber unit. [Diagram 3] FIG. 13 is a diagram showing the shape of a protective plate. [Figure 4] FIG. 4 is a diagram showing the shape of a rear wall side of the arc extinguishing chamber unit. [Diagram 5] 13 is a diagram showing a first holding protrusion and a second holding protrusion provided on the rear wall. FIG. [Figure 6] 13 is a diagram showing the state in which a protective plate is attached toward the rear wall of the arc-extinguishing chamber unit during assembly of the arc-extinguishing device. FIG. [Figure 7] 13 is a diagram showing a state before the base of the protective plate is engaged with the first retaining protrusion and the second retaining protrusion of the rear wall. FIG. [Figure 8] 13 is a view showing a state in which the base of the protective plate is engaged with the first retaining protrusion and the second retaining protrusion of the rear wall. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are given the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc., differ from the actual ones. Therefore, the specific thickness and dimensions should be determined with reference to the following description. In addition, it goes without saying that the drawings include parts with different dimensional relationships and ratios.

[0014] In addition, the embodiments shown below are merely examples of devices and methods for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not specify the materials, shapes, structures, arrangements, etc. of the components to those described below. The technical idea of ​​the present invention can be modified in various ways within the technical scope defined by the claims.

[0015] In the following description, terms indicating directions such as "longitudinal direction" and "width direction" are used with reference to the directions in the accompanying drawings.

[0016] FIG. 1 is a cross-section of a first embodiment of a circuit breaker 1 for three-phase (R, S, T phase) AC connected between the power supply side and the load side of a main circuit, and shows the circuit structure of one of the phases assembled in parallel in a main body case 2.

[0017] The circuit breaker 1 of the first embodiment has, inside a main body case 2, an opening / closing contact 3 for opening and closing the main circuit, an opening / closing mechanism 4 for opening and closing the opening / closing contact 3, an opening / closing handle 5 for operating the opening / closing mechanism 4, an overcurrent trip device 6 for tripping the opening / closing mechanism 4 when a short-circuit current flows in the main circuit, and an arc extinguishing device 7.

[0018] The main body case 2 is constructed by assembling a power supply side intermediate case 2b and a load side intermediate case 2c on top of a lower case 2a, and assembling a top cover 2d on top of the power supply side intermediate case 2b and the load side intermediate case 2c. A power supply side main circuit terminal 8 and a load side main circuit terminal 9 are fixed to the lower case 2a. The switching contacts 3 are constructed of a fixed contactor 10 having a fixed contact 10a and a movable contactor 11 having a movable contact 11a, and the movable contactor 11 is rotatably supported by a contactor holder 12. The fixed contactor 10 is connected to the power supply side main circuit terminal 8, and the movable contactor 11 is connected to the load side main circuit terminal 9 via an overcurrent tripping device 6.

[0019] The opening / closing mechanism 4 is composed of a toggle link mechanism (not shown) that links the movable contact 11 and the opening / closing handle 5, a latch mechanism that combines a latch (not shown) and a trip crossbar 13. When the trip crossbar 13 rotates counterclockwise, the opening / closing mechanism 4 trips, causing the movable contact 11 to perform an opening operation.

[0020] When an overcurrent flows between the power supply side main circuit terminal 8 and the load side main circuit terminal 9, the curved bimetal 6a of the overcurrent trip device 6 comes into contact with the trip crossbar 13 of the switching mechanism 4, causing the trip crossbar 13 to rotate counterclockwise. This causes the movable contactor 11 to perform an opening operation due to the tripping operation of the switching mechanism 4.

[0021] The lower case 2a and the power supply side intermediate case 2b of the main body case 2 form an arc-extinguishing chamber 14 that contains the switching contacts 3, the contact holder 12 and the arc-extinguishing device 7.

[0022] As shown in Figure 2, the arc extinguishing device 7 comprises a box-shaped arc extinguishing chamber unit 16, a plurality of grids 17 arranged in layers inside the arc extinguishing chamber unit 16, and a protective plate 20 attached integrally to the arc extinguishing chamber unit 16.

[0023] The protective plate 20 is formed of an insulating elastically deformable plate material, and has a rectangular main body 21 and a base 22 formed continuously with one end side of the main body 21 in the longitudinal direction, as shown in Fig. 3. The base 22 has a neck 23 formed with a width smaller than the width of the main body 21 in the short direction, and a pair of first engagement pieces 24a, 24b protruding outward in the width direction from a free end of the neck 23 separated from the main body 21. The neck 23 is formed with a through hole 25 that opens in a rectangular shape. In addition, two slits 26a, 26b are formed extending in parallel from the through hole 25 toward the main body 21, and a second engagement piece 27 is formed between these slits 26a, 26b.

[0024] The arc-extinguishing chamber unit 16 is a member formed from a polymeric material, and as shown in Figure 2, has a pair of side walls 30a, 30b arranged opposite each other, an upper wall 31 connected at the upper ends of the pair of side walls 30a, 30b, and a rear wall 32 connected at the rear ends of the pair of side walls 30a, 30b, and an exhaust port 33 communicating with the interior of the arc-extinguishing chamber unit 16 is formed between the upper wall 31 and the rear wall 32.

[0025] 4 shows the rear wall 32 side of the arc extinguishing chamber unit 16 with the protective plate 20 removed. The rear wall 32 of the arc extinguishing chamber unit 16 has a substantially rectangular shape, and an exhaust port 33 is formed at one end 32a in the longitudinal direction. A pair of first holding protrusions 34a, 34b are formed on the other end 32b in the longitudinal direction of the rear wall 32, which are spaced apart from each other in the short length direction and protrude from the rear wall 32, and a second holding protrusion 36 is formed between the pair of first holding protrusions 34a, 34b and protrude from the rear wall 32.

[0026] Hook portions 35a, 35b are formed on parts of the side walls of the pair of first holding protrusions 34a, 34b. As shown in Fig. 5, the hook portions 35a, 35b are formed in a pocket shape by cutting out parts of the side walls of the first holding protrusions 34a, 34b facing the other longitudinal direction 32b of the rear wall 32 and parts of the side walls of the first holding protrusions 34a, 34b facing the second holding protrusion 36.

[0027] 5, a first wall surface 36a facing one side 32a in the longitudinal direction of the rear wall 32 is a right-angled surface rising at a right angle from the rear wall 32, and a second wall surface 36b facing the other side 32b in the longitudinal direction of the rear wall 32 is formed as a gentle slope rising at a small angle from the rear wall 32. The first wall surface 36a corresponds to the side wall of the second retaining protrusion in the present invention.

[0028] The protective plate 20 is attached integrally to the arc extinguishing chamber unit 16 by inserting a portion of the pair of first engagement pieces 24a, 24b of the base 22 into the hook portions 35a, 35b of the pair of first retaining protrusions 34a, 34b and engaging the second engagement piece 27 of the base 22 with the first wall surface 36a of the second retaining protrusion 36.

[0029] The arc extinguishing device 7 having the protective plate 20 attached integrally to the arc extinguishing chamber unit 16 is mounted inside the lower case 2a and power supply side intermediate case 2b of the main body case 2 that form the arc extinguishing chamber 14, together with the switching contacts 3 and the contact holder 12, as shown in Fig. 1. As a result, the protective plate 20 of the arc extinguishing device 7 is disposed in a state where it covers the exhaust port 33 of the arc extinguishing device 7 by engaging the upper end of the main body part 21 with the power supply side intermediate case 2b of the main body case 2. This prevents dust and foreign objects from entering the arc extinguishing chamber 17 under normal conditions.

[0030] In the circuit breaker 1 having the above configuration, when a short-circuit current flows in the main circuit, an electromagnetic repulsive force acts between the fixed contact 10a of the fixed contact 10 and the movable contact 11a of the movable contact 11, and the movable contact 11 performs a current-limiting opening operation. When the movable contact 11 performs a current-limiting opening operation, an arc is generated between the fixed contact 10a and the movable contact 11a. The arc gas in the arc-extinguishing chamber 14 is heated by the arc heat, and the temperature and gas pressure of the arc-extinguishing chamber 14 increase.

[0031] Here, if the holding force of the rear wall 32 to the base 22 of the protective plate 20 is weak, there is a risk that the protective plate 20 will be blown away. However, in this embodiment, the pair of first engagement pieces 24a, 24b of the base 22 of the protective plate 20 are inserted into the hook portions 35a, 35b provided on the rear wall 32, so that the base 22 is restrained from coming off the rear wall 32, and the movement of the rear wall 32 to one side 32a in the longitudinal direction is also restrained. In addition, the tip of the second engagement piece 27 of the base 22 engages with the first wall surface 36a of the second holding protrusion 36, so that the movement of the rear wall 32 to the other side 32b in the longitudinal direction is also restrained.

[0032] Therefore, the base 22 of the protective plate 20 is firmly held by the hook portions 35a, 35b and the second retaining protrusion 36 of a pair of first retaining protrusions 34a, 34b formed on the rear wall 32, so that there is no risk of the protective plate 20 being blown off from the rear wall 32 of the arc extinguishing chamber unit 16 even if the gas pressure in the arc extinguishing chamber 14 increases.

[0033] Furthermore, the arc extinguishing device 7 of this embodiment, which has the protective plate 20 attached as an integral part, can significantly improve the ease of assembly of the circuit breaker 1, and since it does not use double-sided tape as in conventional devices, post-processing work is not required and problems such as a decrease in the adhesive strength of the double-sided tape due to contact with the arc gas do not occur.

[0034] Next, a method for mounting the protective plate 20 to the arc extinguishing chamber unit 16 will be described with reference to FIGS.

[0035] First, as shown in FIG. 6, the arc extinguishing chamber unit 16 is arranged so that the rear wall 32 faces upward.

[0036] Next, the protective plate 20 is lowered downward toward the rear wall 32 of the arc extinguishing chamber unit 16, and the main body 21 is placed on the rear wall 32. At this time, as shown in Fig. 7, the neck portion 23 of the protective plate 20 is placed between the pair of first holding protrusions 34a, 34b, and the pair of first engagement pieces 24a, 24b is placed on the other 32b side in the longitudinal direction of the rear wall 32 than the pair of first holding protrusions 34a, 34b. At this time, the second engagement piece 27 of the protective plate 20 is in contact with the upper surface of the third holding protrusion 36 of the rear wall 32.

[0037] Next, the protective plate 20 is slid toward the one 32a side in the longitudinal direction of the rear wall 32, and the pair of first engagement pieces 24a, 24b of the base 22 is inserted into the hook portions 35a, 35b provided on the rear wall 32. At this time, the second engagement piece 27 of the protective plate 20 contacts the second wall surface 36b of the second holding protrusion 36 and moves to the upper surface of the second holding protrusion 36 while elastically deforming upward. Then, as shown in FIG. 8, the pair of first engagement pieces 24a, 24b that have moved toward the one 32a side in the longitudinal direction of the rear wall 32 abuts against the inner wall provided on the one 32a side in the longitudinal direction of the rear wall 32 of the hook portions 35a, 35b, and the second engagement piece 27 that has moved on the upper surface of the second holding protrusion 36 elastically returns to a state in which it abuts against the first wall surface 36a of the second holding protrusion 36. As a result, the base 22 is restrained from coming off the rear wall 32, and the movement of the base 22 to one side 32a in the longitudinal direction of the rear wall 32 is restrained, and the movement of the base 22 to the other side 32b in the longitudinal direction of the rear wall 32 is also restrained. Therefore, the base 22 of the protective plate 20 is held by the hook portions 35a, 35b and the second holding protrusions 36 of the pair of first holding protrusions 34a, 34b formed on the rear wall 32, and the protective plate 20 is attached to the arc extinguishing chamber unit 16 as a single unit.

[0038] According to the method of mounting the protective plate 20 to the arc extinguishing chamber unit 16 of this embodiment, the process of lowering the protective plate 20 downward and placing it on the rear wall 32 of the arc extinguishing chamber unit 16 with the rear wall 32 facing upward, and the process of sliding the protective plate 20 to one side 32a in the longitudinal direction of the rear wall 32 can be easily performed by holding the protective plate 20 and moving it in two axial directions using mechanical means that eliminates manual labor. As a result, the mounting of the protective plate 20 integrally to the arc extinguishing chamber unit 16 can be automated by assembly using an automatic machine. [Explanation of symbols]

[0039] 1 Circuit Breaker 2 Main unit case 2a Lower Case 2b Power supply intermediate case 2c Load side intermediate case 2d Top cover 3 Switching Contacts 4 Opening and closing mechanism 5 Opening and closing handle 6. Overcurrent tripping device 7 Arc extinguishing device 8 Power supply side main circuit terminal 9 Load side main circuit terminal 10 Fixed contact 10a fixed contact 11 Movable contact 11a Movable contact 12 Contact holder 13 Trip Crossbar 14 Arc room 16 Arc extinguishing chamber unit 17 Grid 20 Protective plate 21 Main body 22 Base 23 Neck 24a, 24b 1st engagement piece 25 through hole 26a, 26b Slit 27 Second engagement piece 30a,30b side wall 31 Upper Wall 32 Back wall 32a One of the longitudinal sides of the rear wall 32b The other longitudinal side of the rear wall 33 Exhaust port 34a, 34b First holding protrusion 35a, 35b Hook part 36 Second retaining protrusion 36a 1st wall 36b 2nd wall

Claims

1. An arc extinguishing device for a circuit breaker, comprising: an arc extinguishing chamber unit disposed inside a case and surrounding a fixed contact and a movable contact; and a protective plate disposed on a rear wall of the arc extinguishing chamber unit so as to cover an exhaust port provided on the rear wall, The protective plate includes a main body portion that covers the exhaust port and a base portion formed at one end of the main body portion, an arc extinguishing device for a circuit breaker, characterized in that the rear wall of the arc extinguishing chamber unit is provided with a protective plate holding portion that prevents the base from separating from the rear wall and prevents the base from moving from the rear wall, thereby attaching the protective plate as a single unit.

2. 2. The arc extinguishing device for a circuit breaker according to claim 1, wherein an engagement piece is provided at a base of the protective plate, and the protective plate is slid to one side in the longitudinal direction of the rear wall to engage the engagement piece with the protective plate holding portion.

3. The base portion includes a pair of first engagement pieces as the engagement pieces protruding outward in the width direction from a free end portion spaced from the main body portion, a through hole formed between the pair of first engagement pieces, and a second engagement piece as the engagement piece formed between two slits on the periphery of the through hole, the protective plate holding portion includes a pair of first holding protrusions formed to be spaced apart from each other in a short dimension direction of the rear wall, a pair of hook portions formed by cutting out pocket-shaped portions of side walls of the pair of first holding protrusions, and a second holding protrusion that fits into the through hole, 3. The arc extinguishing device for a circuit breaker according to claim 2, characterized in that by sliding the base, which is arranged on the other side of the rear wall in the longitudinal direction, to one side of the rear wall in the longitudinal direction, the pair of first engagement pieces are inserted into the pair of hook portions to restrain the base from coming off the rear wall and to restrain the movement of the base to one side in the longitudinal direction of the rear wall, and when the second retaining protrusion enters the through hole, the second engagement piece presses a side wall of the second retaining protrusion, thereby restraining the movement of the base to the other side in the longitudinal direction of the rear wall.

4. A method for assembling the arc extinguishing device according to claim 3, comprising the steps of: moving the protective plate toward the rear wall of the arc extinguishing chamber unit, and placing the protective plate on the rear wall so that the pair of first engagement pieces of the base are positioned on the other side of the longitudinal direction of the rear wall relative to the pair of hook portions of the protective plate holding portion, and the through hole of the base is positioned on the other side of the longitudinal direction of the rear wall relative to the second holding protrusions of the protective plate holding portion; a step of sliding the protective plate to one side in the longitudinal direction of the rear wall, thereby inserting the pair of first engaging pieces into the pair of hook portions, and causing the second retaining protrusion to enter the through hole and for the second engaging piece to press the side wall of the second retaining protrusion.

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