circuit breaker

Abstract

To provide a circuit breaker which can improve its cut-off performance by generating sufficient pyrolysis gas through reliable contact between an arc and an insulation part.SOLUTION: A circuit breaker comprises: a fixed contact piece 2 having a fixed contact 2a; a movable contact piece 3 having a movable contact 3a which comes into contact with or separates from the fixed contact; a plurality of magnetic grids 4 which extinguish an arc 12 generated between the fixed contact and the movable contact; a pair of resin members 5, 5 which are disposed to face each other along a moving path of the movable contact, and which generate pyrolysis gas when they make contact with the arc; and a pair of magnetic driving parts 6, 7 which forms a magnetic path together with the magnetic grids so that the arc generated between the contacts causes a magnetic flux to flow through the magnetic path, thereby driving the pair of resin members in a direction for making contact with the arc.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a circuit breaker that is applied to a molded case circuit breaker, an earth leakage breaker, or the like. [Background technology]

[0002] In recent years, with the trend toward larger capacity and more space-saving low-voltage wiring facilities, there has been a strong demand for improved interrupting performance of circuit breakers.

[0003] As a circuit breaker with improved interruption performance, there is known a device in which a plurality of arc-extinguishing grid plates are provided in an arc-extinguishing chamber and an insulator that generates pyrolysis gas when melted is arranged on a fixed contact (for example, Patent Document 1).

[0004] The circuit breaker of Patent Document 1 includes multiple arc-extinguishing grid plates made of a magnetic material, arranged side by side along the opening and closing direction of the fixed and movable contacts, with their surfaces facing each other. When an arc occurs between the fixed contact of the fixed contact and the movable contact of the movable contact, the magnetic field of the arc current passes through the arc-extinguishing grid plates, causing a Lorentz force to act on the arc. The arc is then driven toward the arc-extinguishing grid plates, causing the arc to extend. The arc is then split by the arc-extinguishing grid plates, increasing the arc voltage due to the electrode drop voltage. Furthermore, when the insulators disposed on the fixed contacts melt due to heat transfer from the arc and generate pyrolysis gas, the pressure in the arc-extinguishing chamber increases, thereby increasing the arc voltage. In this way, the arc is extinguished, resulting in current-limiting interruption. This is due to the electrode drop voltage caused by the arc splitting by the arc-extinguishing grid plates and the increase in pressure in the arc-extinguishing chamber due to the generation of pyrolysis gas.

[0005] In addition, when an arc comes into contact with an insulator and pyrolysis gas is generated, the flow of the pyrolysis gas makes it easier for the arc to extend toward the arc-extinguishing grid plate, and the pyrolysis gas mixes with the arc, causing it to break and ionize, thereby dissipating the arc energy. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-59759 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the insulator disposed on the fixed contact of the circuit breaker in Patent Document 1 is located at a position away from the fixed contact of the arc-extinguishing grid plate, so the arc driving toward the arc-extinguishing grid plate does not come into contact with the insulator, making it difficult for pyrolysis gas to be generated. If pyrolysis gas is not generated in this way, the effects of increasing the arc voltage, extending the arc, and dissipating the arc energy are reduced.

[0008] The present invention has been made in view of the above-described circumstances, and aims to provide a circuit breaker that can improve interruption performance by ensuring that the arc comes into contact with the insulating part and sufficiently generating pyrolysis gas. [Means for solving the problem]

[0009] In order to achieve the above object, the circuit breaker of the present invention comprises a fixed contactor having a fixed contact, a movable contactor having a movable contact that disconnects from the fixed contact, a plurality of magnetic grids that extinguish an arc generated between the fixed contactor and the movable contact, a pair of resin members arranged opposite each other along the moving path of the movable contactor and that generate pyrolysis gas upon contact with the arc, and a pair of magnetic drive units that form a magnetic path together with the magnetic grids, and in which an arc generated between the contacts causes magnetic flux to flow in the magnetic path, driving the pair of resin members in a direction that brings them into contact with the arc. [Effects of the Invention]

[0010] According to the circuit breaker of the present invention, the arc reliably contacts the insulating portion to generate sufficient pyrolysis gas, thereby improving the interrupting performance. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing a main part of a circuit breaker according to the present invention; [Figure 2] FIG. 2 is a front view of the main part of the circuit breaker. [Figure 3] 10 is a left side view showing a state in which no arc is generated between the fixed contact and the movable contact and the pair of resin members are arranged in a normal state. FIG. [Figure 4] 1 is a top view of a main part of a circuit breaker in an initial state where an arc is generated between a fixed contact and a movable contact. FIG. [Figure 5] 10 is a diagram showing a state in which an arc is generated between the fixed contact and the movable contact, and the pair of resin members have moved to a position where they come into contact with the arc, as viewed from above. FIG. [Figure 6] 10 is a left view showing a state in which an arc is generated between the fixed contact and the movable contact, and the pair of resin members have moved to a position where they come into contact with the arc. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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 designated by 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., may differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following description. Furthermore, it goes without saying that the drawings may include parts with different dimensional relationships and ratios.

[0013] Furthermore, the embodiments shown below are merely examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the materials, shapes, structures, arrangements, etc. of the components to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

[0014] A circuit breaker 1 according to one embodiment of the present invention, which is applicable as a molded case circuit breaker or an earth leakage circuit breaker, will be described with reference to Figures 1 to 6. In each drawing, the configuration of each component will be described with specific directions such as up, down, front, back, left, and right.

[0015] 1 and 2, the circuit breaker 1 of this embodiment includes a fixed contact 2 having a fixed contact 2a, a movable contact 3 having a movable contact 3a that moves in contact with and out of contact with the fixed contact 2a, and a plurality of magnetic grids 4 arranged on the left side of the fixed contact 2a at a distance. As shown in FIG. 3, the circuit breaker 1 of this embodiment further includes a pair of resin members 5, 5 that are arranged facing each other and extending in the vertical direction so as to sandwich the movement locus T of the movable contact 3a from the front-to-rear direction, a pair of plate-shaped first magnetic yokes 6, 6 that are arranged inside the pair of resin members 5, 5 and extend in the vertical direction, a pair of magnetic pins 7, 7 that penetrate the pair of first magnetic yokes 6, 6 in the plate thickness direction and engage with the pair of resin members 5, 5, and a second magnetic yoke 8 that extends in the vertical direction and is adjacent to the lower end of the pair of first magnetic yokes 6, 6. These components of the circuit breaker 1 are housed inside a breaker tube 9 made of an insulating resin material, as shown in FIG. 3. The movable contact housed in the circuit breaker cylinder may be a single-break movable contact or a double-break movable contact.

[0016] 2, the fixed contact 2 includes a flat substrate portion 2b and a contact side plate portion 2c that is bent upward from the right end of the substrate portion 2b and then further bent toward the left, with the fixed contact 2a provided on the upper surface of the contact side plate portion 2c. An arc runner 10 is provided on the upper surface of the contact side plate portion 2c to the left of the fixed contact 2a.

[0017] The movable contactor 3 is a conductor having a movable contact 3a on the underside of the left end and a support shaft portion (not shown) extending in the front-to-rear direction at the right end, and is arranged to be freely rotatable via the support shaft portion so that the movable contact 3a can come into and out of contact with the fixed contact 2a.

[0018] The magnetic grids 4 are flat plate-shaped members formed from a magnetic material, and are arranged in parallel in the vertical direction with their surfaces facing each other and at equal intervals.

[0019] The pair of first magnetic yokes 6, 6 are rectangular plate-shaped members made of a soft magnetic material such as iron, and as shown in Figure 3, they have a pin through-hole 6a that penetrates through the plate thickness direction at one end in the longitudinal direction, and a support rod through-hole 6b that penetrates through the plate thickness direction at the other end in the longitudinal direction.

[0020] The pair of resin members 5, 5 are formed of a polymeric material made of a resin such as polyamide, polyacetal, or polyester that generates pyrolysis gas upon thermal decomposition, and are provided with an arc melted portion 5a that protrudes in a mountain shape with inclined surfaces from both longitudinal ends, an inner portion 5b formed as a rectangular parallelepiped recess on the back side of the arc melted portion 5a, and a support rod 5c that protrudes from one end of the inner portion 5b in the opposite direction to the protruding direction of the arc contact portion 5a. As shown in Fig. 1, the pair of resin members 5, 5 are connected together via a resin bridge portion 5d with the arc melted portions 5a facing each other.

[0021] The pair of magnetic pins 7, 7 are members formed from a soft magnetic material such as iron, and as shown in Figure 3, each has a cylindrical insertion portion 7a that is inserted into the pin through hole 6a of the first magnetic yoke 6, and a cylindrical head portion 7b with a larger diameter than the insertion portion 7a.

[0022] Each of the pair of resin members 5, 5 has a first magnetic yoke 6 disposed inside the inner container portion 5b with a support rod 5c inserted through a support rod through-hole 6b. A magnetic pin 7 is attached with an insertion portion 7a inserted through a pin through-hole 6a of the first magnetic yoke 6 and the tip of the insertion portion 7a in contact with the bottom wall of the inner container portion 5b. A ring-shaped elastic body 11 is attached to the outer periphery of the insertion portion 7a that is not inserted through the pin through-hole 6a.

[0023] 3, support holes 9a1, 9b1 are formed in the front-rear side walls 9a, 9b of the circuit breaker cylinder 9. Support rods 5c of a pair of resin members 5, 5, in which the first magnetic yoke 6, magnetic pin 7, and annular elastic body 11 are arranged, are inserted into and engaged with these support holes 9a1, 9b1. As a result, the pair of resin members 5, 5 are supported by the side walls 9a, 9b of the circuit breaker cylinder 9 with their arc melted portions 5a facing each other so as to sandwich the movement locus T of the movable contact 3a from the front-rear direction.

[0024] In addition, the pair of magnetic drive units described in the present invention are composed of a pair of first magnetic yokes 6, 6 and a pair of magnetic pins 7, 7, and the magnetic yoke of the present invention corresponds to the first magnetic yoke 6, the pin insertion portion of the present invention corresponds to the insertion portion 7a, and the pin head portion of the present invention corresponds to the head portion 7b.

[0025] Next, the operation of the circuit breaker 1 of this embodiment will be described.

[0026] When an overcurrent such as a short-circuit current or an overload current flows through the circuit breaker 1 configured as described above, an electromagnetic repulsive force due to the concentrated current acts between the fixed contact 2a and the movable contact 3a, opening the movable contact 3. Then, at the same time as the movable contact 3 opens, an arc 12 is generated between the fixed and movable contacts 2a and 3a in the direction of current flow from the fixed contact 2a to the movable contact 3a, as shown in Figure 2.

[0027] When an arc 12 is generated between the fixed and movable contacts 2a and 3a, a Lorentz force F acts toward the magnetic grid 4 according to Fleming's left-hand rule due to the direction of current flow in the arc 12 and the self-magnetic flux φ1, as shown in Fig. 4. Furthermore, the self-magnetic flux φ1 generated in the arc 12 forms a magnetic path through which a magnetic flux φ2 flows in the pair of first magnetic yokes 6, 6 disposed inside the pair of resin members 5, 5 and the magnetic grid 4.

[0028] As shown in FIG. 5, the arc 12 on which the Lorentz force F acts is extended as the arc end on the fixed contact 2a side is driven toward the arc runner 10 side, and is then broken by contact with the magnetic grid 4, and the arc voltage is increased by the electrode drop voltage.

[0029] Then, when a magnetic path through which magnetic flux φ2 flows is formed in the pair of first magnetic yokes 6, 6 and the magnetic grid 4, as shown in FIG. 6, the head 7b of the magnetic pin 7 moves toward the first magnetic yoke 6 due to attraction. At this time, the annular elastic body 11 is elastically compressed. As the head 7b of the magnetic pin 7 moves toward the first magnetic yoke 6, the tip of the insertion portion 7a presses against the bottom wall of the enclosed portion 5b of the resin member 5. As a result, the pair of resin members 5, 5 tilt while elastically deforming with the support rod 5c as a fulcrum, and the arc fusion zones 5a of the pair of resin members 5, 5 come into contact with the arc 12. The arc fusion zones 5a in contact with the arc 12 melt, generating a large amount of pyrolysis gas, which increases the pressure inside the circuit breaker 9 and increases the arc voltage.

[0030] As the arc 12 disappears, the magnetic path through which magnetic flux flows disappears between the pair of first magnetic yokes 6, 6 and the magnetic grid 4, and the first magnetic yoke 6 no longer has the effect of attracting the head 7b of the magnetic pin 7, so the elastic restoring force of the elastically compressed annular elastic body 11 moves the head 7b of the magnetic pin 7 in a direction away from the first magnetic yoke 6. As a result, the pair of resin members 5, 5 that had been tilted with the support rod 5c side as a fulcrum return to their original state (the state shown in FIG. 3) due to the elastic restoring force.

[0031] Next, the effects of the circuit breaker 1 of this embodiment will be described.

[0032] In the circuit breaker 1 of this embodiment, the arc 12 extended by being driven toward the arc runner 10 is broken by coming into contact with the magnetic grid 4, and the arc voltage is sufficiently increased by the electrode drop voltage, and the arc melting portion 5a in contact with the arc 12 melts, generating pyrolysis gas, which increases the pressure inside the circuit breaker tube 9 and sufficiently increases the arc voltage, thereby quickly extinguishing the arc 12 and current-limiting interruption, thereby improving the interruption performance of the circuit breaker 1.

[0033] Furthermore, the flow of pyrolysis gas generated in the circuit breaker tube 9 makes it easier for the arc 12 to extend toward the magnetic grid 4, and the pyrolysis gas mixes with the arc 12, causing it to break and ionize, thereby dissipating the arc energy and further improving the interrupting performance of the circuit breaker 1.

[0034] Furthermore, when the generation of the arc 12 forms a magnetic path through which magnetic flux φ2 flows in the pair of first magnetic yokes 6, 6 and the magnetic grid 4, the head 7b of the magnetic pin 7 moves toward the first magnetic yoke 6 due to its attraction action, tilting the pair of resin members 5, 5 and bringing the arc melted portion 5a into contact with the arc 12, so that the arc melted portion 5a in contact with the arc 12 melts and generates a large amount of pyrolysis gas.

[0035] Furthermore, since the tip of the arc melted portion 5a protrudes in a mountain shape, it is structured so that when it comes into contact with the arc 12, it melts immediately and easily generates pyrolysis gas. [Explanation of symbols]

[0036] 1 Circuit Breaker 2 Fixed contact 2a fixed contact 2b Board part 2c Contact side plate 3 Moving contact 3a Movable contact 4 Magnetic grid 5 Resin parts 5a Arc fusion zone 5b Inner capsule 5c Support rod 5d Resin crosslinking part 6. First magnetic yoke (magnetic yoke) 6a Pin through hole 6b Support rod through hole 7 magnetic pins 7a Insertion part (pin insertion part) 7b Head (Pin Head) 8. Second magnetic yoke 9. Barrier 9a,9b side wall 9a1,9b1 Support hole 10 Arc Runner 11 Annular elastic body (elastic body) 12 Arc T Moving contact movement path φ1 Self-flux φ2 magnetic flux

Claims

1. a fixed contactor having a fixed contact; a movable contactor having a movable contact that separates from the fixed contact; a plurality of magnetic grids for extinguishing arcs generated between the fixed contacts and the movable contacts; a pair of resin members disposed opposite each other along a moving path of the movable contact, the resin members generating a pyrolysis gas upon contact with the arc; a pair of magnetic drive sections that form a magnetic path together with the magnetic grid, and an arc generated between the contacts causes magnetic flux to flow in the magnetic path, driving the pair of resin members in a direction to contact the arc.

2. 2. The circuit breaker according to claim 1, wherein arc fusion portions protruding in a mountain shape are formed on the surfaces of the pair of resin members facing the movable contacts.

3. the pair of magnetic drive units include a pair of magnetic yokes arranged along back surfaces of the pair of resin members that do not face the movable contacts, and a pair of magnetic pins each having a pin insertion portion and a pin head portion provided at one end of the pin insertion portion, the pin insertion portion is inserted into a pin through-hole formed in the magnetic yoke, and the tip of the pin insertion portion is brought into contact with the back surface of the resin member, and the magnetic pin is positioned with the pin head spaced apart from the magnetic yoke; 3. The circuit breaker according to claim 1, wherein when the arc is generated and magnetic flux flows in the magnetic path, causing the pin head of the magnetic pin to move toward the magnetic yoke due to attraction, the pin insertion portion presses against the resin member, causing the resin member to move in a direction that contacts the arc.

4. 4. The circuit breaker according to claim 3, wherein the resin member moves in a direction to contact the arc while elastically deforming.

5. 5. The circuit breaker according to claim 4, wherein an elastic body is disposed in the pin insertion portion between the pin head and the magnetic yoke, and when the adhesive action on the pin head is lost, the elastic restoring force of the elastic body moves the pin head in a direction away from the magnetic yoke.

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