Circuit breaker

Abstract

To provide a circuit breaker comprising a protection cover which can surely insulate a movable contactor without dropping even if a tip end side of the movable contactor is deformed without deteriorating a breaking performance.SOLUTION: A circuit breaker comprises a protection cover 11 formed by an insulation material that covers a lower surface and both side surfaces of a movable contactor 5 to prevent the movement of an arc generated in a movable contact point 8 provided on a tip end side of the movable contactor at a time of an open electrode operation of the movable contactor to a root side of the movable contactor. The protection cover is constructed by: a tip end cover 12 mounted onto a tip end part 5a of the movable contactor on the neighbor of the movable contact point; and a root cover 13 mounted onto a root part 5b of the movable contactor. Then, when the tip end part of the movable contactor in the open electrode operation, the tip end cover is moved while tracking the deformation of the tip end part, and the root cover prevents a dropping of the tip end cover.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a circuit breaker provided with a protective cover that covers a movable contact so as to prevent an arc generated during the opening operation of the movable contact from moving to the root side of the movable contact.

Background Art

[0002] A circuit breaker generates an arc between a movable contact and a fixed contact by opening the movable contact during interruption, and rapidly extinguishes the arc by the current-limiting effect due to the arc resistance and by the arc entering the arc extinction chamber and being interrupted. When the distance between the root side of the movable contact and the fixed contact is close to the distance between the fixed contact and the movable contact at the opening position of the movable contact, an arc may be generated between the root side of the movable contact and the fixed contact, and the arc may not enter the arc extinction chamber, or may enter the arc extinction chamber late, resulting in a situation where interruption is impossible. Therefore, the circuit breaker of Patent Document 1 is equipped with a protective cover made of an insulating material that covers the lower surface and both side surfaces of the movable contact from the tip side to the root side of the movable contact, avoiding the generation of an arc between the root side of the movable contact and the fixed contact.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, since the protective cover of Patent Document 1 is a component with an integral structure that is continuous from the tip side to the root side of the movable contact, when the tip side of the movable contact is deformed during the opening operation at the time of interruption, the protective cover is damaged, and a part of the damaged protective cover falls on the fixed contact, which may inhibit the function of the circuit breaker. As a method of suppressing the deformation of the movable contact, there is a method of increasing the thickness and width of the movable element to increase the rigidity, but the moment of inertia of the movable contact increases, and there is a risk that the interruption performance will decrease due to the decrease in the opening speed. Also, a method of suppressing the electromagnetic force or the like in the opening direction generated in the movable contact can be considered, but similarly, there is a risk that the interruption performance will decrease due to the decrease in the opening speed. Thus, the method of increasing the rigidity of the movable contact has problems in terms of interruption performance.

[0005] The present invention has been made in view of such problems, and an object thereof is to provide a circuit breaker provided with a protective cover that can surely insulate the movable contact without dropping even if the tip of the movable contact is deformed without degrading the interruption performance.

Means for Solving the Problems

[0006] In order to achieve the above object, a circuit breaker according to an aspect of the present invention is a circuit breaker provided with a protective cover formed of an insulating material that covers the lower surface and both side surfaces of a movable contact so as to prevent an arc generated at a movable contact provided on the tip side of the movable contact from moving to the root side of the movable contact during the opening operation of the movable contact. The protective cover includes a tip cover attached to the tip of the movable contact near the movable contact, and a root cover attached to the root of the movable contact. When the tip of the movable contact is deformed during the opening operation, the tip cover moves following the deformation of the tip, and the root cover prevents the tip cover from dropping off.

Effects of the Invention

[0007] According to the circuit breaker of the present invention, the protective cover is composed of a tip cover that covers the tip of the movable contact and a base cover that covers the base of the movable contact. When the tip of the movable contact deforms during the opening operation, the tip cover moves following the deformation of the tip, and the base cover prevents the tip cover from falling off. Therefore, even if the tip of the movable contact deforms, it does not fall off, and the insulation of the movable contact can be ensured without degrading the interruption performance.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0009] Next, embodiments 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 denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thicknesses of the respective layers, etc. are different from the actual ones. Therefore, the specific thicknesses and dimensions should be determined in consideration of the following description. Also, it goes without saying that there are portions where the dimensional relationships and ratios are different between the drawings.

[0010] Further, the embodiments shown below exemplify 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 as the following. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims. Note that terms indicating directions such as "longitudinal direction", "lateral direction", and "vertical direction" described in the following description are used with reference to the directions of the attached drawings.

[0011] [First Embodiment] FIG. 1 is a cross-sectional view of a main part of a three-pole circuit breaker according to the first embodiment of the present invention. In the circuit breaker shown in FIG. 1, inside an insulating container composed of a case 1 and a cover 2, a breaking part is constituted by a fixed contact 3 fixed to the case 1 and an elongated plate-shaped movable contact 5 that is driven to open and close by an opening / closing mechanism 4. An arc extinguishing chamber 6 is installed in this breaking part. The insulating container is internally partitioned into three-phase spaces by phase partition walls, and each phase breaking part is accommodated in each space. The fixed contact 3 has a power supply side terminal 3a integrally formed at one end and a fixed contact 3b provided at the other end. The movable contact 5 having a movable contact 8 that makes contact with and separates from the fixed contact 3b is rotatably supported by the case 1 with an opening / closing shaft 7a integral with a holder 7 as a fulcrum, and is driven to open and close by the opening / closing mechanism 4. The arc extinguishing chamber 6 has a configuration in which a plurality of grids 10 made of a magnetic material are stacked and supported vertically at appropriate intervals on a pair of left and right side walls 9 of a support of an insulator. The grid 10 has a U-shape provided with a notch through which the movable contact 5 passes when the movable contact 5 is driven.

[0012] The fixed contact point 3b of the fixed contact 3 and the movable contact point 8 of the movable contact 5 are in the closed state, and current flows through the current path of the power supply side terminal 3a, the fixed contact 3, the movable contact 5, and the load side terminal 5c. When the current flowing through the current path is in an overload state, the opening / closing mechanism 4 is driven to open by the command of an overcurrent tripping device (not shown), and the movable contact 5 rotates with the opening / closing shaft 7a as a fulcrum, and the movable contact point 8 separates from the fixed contact point 3b of the fixed contact 3 to enter the open state.

[0013] A protective cover 11 is attached to the movable contact 5. The protective cover 11 is formed of a thermoplastic insulating material such as plastic. As shown in FIG. 2, it is composed of a tip cover 12 attached to one end side in the longitudinal direction of the movable contact 5 (the tip portion 5a close to the movable contact point 8 of the movable contact 5), and a base cover 13 that engages with the tip cover 12 and is attached to the other end side in the longitudinal direction of the movable contact 5 (the base portion 5b far from the movable contact point 8).

[0014] As shown in FIG. 3, the tip cover 12 includes a tip bottom plate portion 14 that covers the lower surface of the tip portion 5a of the movable contact 5, a pair of tip side plate portions 15, 15 that rise parallel from the short-side edge portions of the tip bottom plate portion 14 to cover both side surfaces of the tip portion 5a of the movable contact 5, and tip engaging convex portions 16 formed on the inner walls of the pair of tip side plate portions 15, 15 on the side close to the movable contact point 8. Further, tip engaging edges 17 that engage with the base cover 13 are formed on the edges of the pair of tip side plate portions 15, 15 on the side far from the movable contact point 8.

[0015] As shown in FIG. 3, the base cover 13 includes a base bottom plate portion 18 that covers the lower surface of the base portion 5b of the movable contact 5, a pair of base side plate portions 19, 19 that rise parallel from the short-side edges of the base bottom plate portion 18 to cover both side surfaces of the base portion 5b of the movable contact 5, a first base engaging convex portion 20 formed on the inner wall of the base side plate portion 19 closer to the tip cover 12, and a second base engaging convex portion 21 formed on the inner wall of the base side plate portion 19 farther from the tip cover 12. Further, a base engaging side 22 that engages with the tip engaging side 17 of the tip cover 12 is formed at the edge of the pair of base side plate portions 19, 19 closer to the tip cover 12.

[0016] The movable contact 5 is a member with low rigidity without increasing its thickness or width, and there is a risk of deformation when it collides with the inner wall 2a in the insulating container during the opening operation at the time of interruption. As shown in FIG. 4, a first through hole 23 is formed in the tip portion 5a of the movable contact 5, and a second through hole 24 and a third through hole 25 are formed in the base portion 5b. Then, as shown in FIG. 2, by fitting the first base engaging convex portion 20 of the base cover 13 into the second through hole 24 of the movable contact 5 and fitting the second base engaging convex portion 21 into the third through hole 25, the base cover 13 is attached in a state of covering the lower surface and both side surfaces of the base portion 5b of the movable contact 5.

[0017] Further, the tip engaging convex portion 16 of the tip cover 12 is fitted into the first through hole 23 of the movable contact 5, and the tip cover 12 is attached in a state of covering the lower surface and both side surfaces of the tip portion 5a of the movable contact 5 with the tip engaging side 17 of the tip cover 12 placed on the upper part of the base engaging side 22 of the base cover 13. Here, as shown in FIG. 2, the tip engaging side 17 of the tip cover 12 and the base engaging side 22 of the base cover 13 are in contact with each other in a state of having an upward inclination as they are separated from the movable contact 8 in the longitudinal direction of the movable contact 5.

[0018] Next, the operation and action of the circuit breaker of this embodiment will be described. When a large current such as a short-circuit current flows through the current path of the circuit breaker according to the embodiment, the opening / closing mechanism 4 performs an opening drive according to a command of the overcurrent tripping device, so that the movable contact 5 rotates with the opening / closing shaft 7a as a fulcrum, and the movable contact 8 separates from the fixed contact 3b of the fixed contact 3 to perform an opening operation.

[0019] The movable contact 5 that performs the opening operation may be deformed when it collides with the inner wall 2a in the insulating container. When the movable contact 5 collides with the inner wall 2a, as shown in FIG. 5, the tip portion 5a is greatly deformed downward, and the root portion 5b is also slightly deformed downward. In FIG. 5, the two-dot chain line indicates the state of the movable contact 5 before deformation, and the solid line indicates the state of the movable contact 5 after deformation. When the root portion 5b of the movable contact 5 is slightly deformed downward, the first and second root engaging convex portions 20 and 21 of the root cover 13 slightly rotate in the second and third through holes 24 and 25, but the root cover 13 maintains the state of being mounted on the root portion 5b.

[0020] On the other hand, when the tip portion 5a of the movable contact 5 is greatly deformed, the tip engaging convex portion 16 of the tip cover 12 rotates in the first through hole 23, and the tip cover 12 also moves downward following the tip portion 5a. When the tip cover 12 moves downward, the tip engaging side 17 of the tip cover 12 slides on the root engaging side 22 of the root cover 13 and slightly moves toward the movable contact 8 side, but maintains the state of being placed on the upper portion of the root engaging side 22. That is, when the tip side of the movable contact 5 is deformed, the tip engaging side 17 is locked to the root engaging side 22.

[0021] Next, the effects of the circuit breaker according to the present embodiment will be described. The circuit breaker of this embodiment is configured such that when a large current such as a short-circuit current flows through the current path and an arc is generated between the movable contact 8 and the fixed contact 3b due to the opening operation of the movable contact 5, a protective cover 11 is attached that continuously covers the lower surface and both side surfaces of the movable contact 5 from a position near the movable contact 8 of the movable contact 5 to the base portion 5b. Therefore, there is no location where an arc is generated between the fixed contact 3b and the base portion 5b of the movable contact 5. For this reason, the arc generated between the movable contact 8 and the fixed contact 3b immediately moves to the arc chute 6 side and is interrupted, so that the interruption performance can be improved.

[0022] Also, the movable contact 5 has a low-rigidity shape with no increase in thickness or width and does not suppress electromagnetic forces in the opening direction or the like, so it does not reduce the interruption performance of the circuit breaker. Further, when the tip portion 5a of the movable contact 5 is greatly deformed by the opening operation of the movable contact 5, the tip engaging convex portion 16 of the tip cover 12 rotates within the first through hole 33 of the movable contact 5, and the tip cover 12 also moves downward following the tip portion 5a. However, the base engaging edge 22 of the base cover 13 attached to the base portion 5b of the movable contact 5 supports the tip engaging edge 17 of the tip cover 12 by placing it thereon. In this way, when the tip portion 5a of the movable contact 5 is greatly deformed, the tip cover 12 deforms following it, and the base cover 13 reliably prevents the tip cover 12 from falling downward (towards the fixed contact 3b side). Therefore, the protective cover 11 that reliably insulates the movable contact 5 can be attached.

[0023] Also, since the tip cover 12 and the base cover 13 are in contact with each other with the tip engaging edge 17 and the base engaging edge 22 inclined upward as they separate from the movable contact 8 in the longitudinal direction of the movable contact 5, for example, the contact area can be increased compared to the case where the tip engaging edge 17 and the base engaging edge 22 are in contact along the longitudinal direction. Even if the amount of deformation of the tip portion 5a of the movable contact 5 increases, the base cover 13 can reliably prevent the tip cover 12 from falling off.

[0024] [Second Embodiment] Next, FIGS. 6 to 8 show the structure in which the protection cover 30 according to the second embodiment of the present invention is attached to the movable contact 5. Note that the same reference numerals are given to the same components as those of the circuit breaker according to the first embodiment shown in FIGS. 1 to 5, and the description thereof is omitted. As shown in FIG. 6, the protection cover 30 according to the second embodiment includes a tip cover 12 attached to the tip portion 5a of the movable contact 5 and a base cover 13 attached to the base portion 5b of the movable contact 8. As shown in FIG. 7, the tip cover 12 includes a tip bottom plate portion 14, a pair of tip side plate portions 15, 15, a tip engaging convex portion 16, and a tip engaging side 17. The base cover 13 also includes a base bottom plate portion 18, a pair of base side plate portions 19, 19, a first base engaging convex portion 20, a second base engaging convex portion 21, and a base engaging side 22.

[0025] As shown in FIGS. 6 and 7, before the protection cover 30 of the present embodiment is attached to the movable contact 5, or when the tip portion 5a is not deformed in a state where the protection cover 30 is already attached to the movable contact 5 as shown in FIG. 6, the tip cover 12 and the base cover 13 are formed of a single part. That is, the opposing portions of the pair of tip side plate portions 15, 15 of the tip cover 12 and the base side plate portions 19, 19 of the base cover 13 are connected via a connecting portion 31. Here, the rigidity of the connecting portion 31 is set to be low enough to be broken by an external force applied when the tip portion 5a of the movable contact 5 is deformed, so as to separate the tip cover 12 and the base cover 13.

[0026] The protection cover 30 having the above configuration is attached to the movable contact 5 in a state where the first base engaging convex portion 20 of the base cover 13 is fitted into the second through hole 24 of the movable contact 5, the second base engaging convex portion 21 is fitted into the third through hole 25, and the tip engaging convex portion 16 of the tip cover 12 is fitted into the first through hole 23 of the movable contact 5, covering the lower surface and both side surfaces of the movable contact 5. At this time, the tip engaging side 17 of the tip cover 12 and the base engaging side 22 of the base cover 13 are arranged in a facing state.

[0027] Next, FIG. 8 shows a state where the movable contact 5 with the protective cover 30 of the present embodiment performs an opening operation, collides with the inner wall 2a in the insulating container, the tip portion 5a is greatly deformed downward, and the root portion 5b is also slightly deformed downward. When the tip portion 5a of the movable contact 5 is greatly deformed downward, the tip cover 12 also moves downward following it, so that the connecting portion 31 of the protective cover 30 is broken and the tip cover 12 and the root cover 13 are separated. Then, as the tip cover 12 moves downward following the tip portion 5a, the tip engaging side 17 of the tip cover 12 rests on the root engaging side 22 of the root cover 13 and slightly moves toward the movable contact 8 side, but maintains a state of resting on the upper portion of the root engaging side 22.

[0028] Therefore, also in the protective cover 30 of the present embodiment, when the tip portion 5a of the movable contact 5 is greatly deformed, the tip cover 12 deforms following it, and the root cover 13 surely prevents the tip cover 12 from dropping downward (toward the fixed contact 3b side), so that the insulation of the movable contact 5 can be surely performed. Further, before being attached to the movable contact 5, the protective cover 30 of the present embodiment is composed of a single part in which the tip cover 12 and the root cover 13 are connected via the connecting portion 31, so that parts management can be easily performed. Also, since the single-part protective cover 30 only needs to be attached to the movable contact 5, the assembly work can also be easily performed.

[0029] In the first and second embodiments described above, the tip engaging side 17 of the tip cover 12 and the root engaging side 22 of the root cover 13 are in contact with each other in a state of having an upward inclination as they are separated from the movable contact 8 in the longitudinal direction of the movable contact 5. However, even if the tip engaging side 17 and the root engaging side 22 are formed so as to have a downward inclination and contact each other as they are separated from the movable contact 8, the same effect can be achieved. Also, in the second embodiment, the connecting portion 31 that connects the tip cover 12 and the root cover 13 has been described as being formed at the opposing portions of the pair of tip side plate portions 15, 15 of the tip cover 12 and the root side plate portions 19, 19 of the root cover 13. However, it may be formed at the portion that connects the tip cover 12 and the root cover 13 at other locations.

Description of Symbols

[0030] 1 case 2 cover 2a inner wall 3 fixed contact 3a power supply side terminal 3b fixed contact point 4 opening / closing mechanism 5 movable contact 5a tip of the movable contact 5b base of the movable contact 6 arc extinguishing chamber 7 holder 7a opening / closing shaft 8 movable contact point 9 side wall 10 grid 11, 30 protective cover 12 tip cover 13 base cover 14 tip bottom plate part 15 tip side plate part 16 tip engaging convex part 17 tip engaging side (tip cover engaging part) 18 base bottom plate part 19 pair of base side plate parts 20 first base engaging convex part 21 second base engaging convex part 22 base engaging side (base cover engaging part) 23 first through hole 24 second through hole 25 third through hole 31 connecting part

Claims

1. In a circuit breaker provided with a protective cover formed of an insulating material that covers the lower surface and both side surfaces of a movable contact so as to prevent an arc generated at a movable contact provided on the tip side of the movable contact from moving to the base side of the movable contact during the opening operation of the movable contact, the protective cover is composed of a tip cover attached to the tip portion of the movable contact near the movable contact and a base cover attached to the base portion of the movable contact, when the tip portion of the movable contact is deformed by the opening operation, the tip cover moves following the deformation of the tip portion, and the base cover prevents the tip cover from falling off. A circuit breaker characterized by this.

2. On the inner wall of the base cover, base engaging protrusions are formed on the side close to and far from the tip cover, and on the base portion of the movable contact, a plurality of base-side through holes into which the base engaging protrusions fit are formed, a tip engaging protrusion is formed at a position on the inner wall of the tip cover close to the movable contact, and on the tip portion of the movable contact, a tip-side through hole into which the tip engaging protrusion fits is formed, a tip cover engaging portion is formed at a position on the tip cover close to the base cover, and a base cover engaging portion is formed at a position on the base cover close to the tip cover. When the tip side of the movable contact is deformed by the opening operation, the tip cover engaging portion is locked to the base cover engaging portion. The circuit breaker according to Claim 1, characterized by this.

3. The tip cover and the base cover constituting the protective cover cover the tip portion and the base portion of the movable contact in an integrated state via a connecting portion, and when the tip side of the movable contact is deformed by the opening operation, the connecting portion is broken and the tip cover and the base cover are separated. The circuit breaker according to Claim 1 or 2, characterized by this.

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