Circuit breaker

Abstract

To make it possible to maintain an open pole position of a movable contact with a simple structure during current limiting cutoff and to be applicable to a small-sized model in a circuit breaker.SOLUTION: At a fixed contact 12, a fixed contact point 33 is formed. A movable contact 13 is supported rotatably, a movable contact point 34 is formed outside in a radial direction, and the movable contact point 34 is brought into contact with or leaves the fixed point 33 by rotation. A magnetic substance 41 is provided between the movable contact 34 and rotary center of the movable contact 13. A magnetic substance 42 is provided on a middle cover 22 and faces the magnetic substance 41 when the movable contact 13 is opened; when the movable contact 13 is opened by an electromagnetic repulsive force during short circuit, the magnetic substance 41 and the magnetic substance 42 are absorbed to each other by a magnetic path being formed around an axis in a conducting direction flowing in the movable contact 13 by an arc.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a circuit breaker.

Background Art

[0002] There is known a current-limiting circuit breaker provided with a movable contact supported rotatably, which, when a short circuit occurs, causes the movable contact to bounce up by electromagnetic repulsive force and open the pole before a tripping operation of a trip device. As such a circuit breaker, for example, in Patent Document 1, a latch mechanism for maintaining the open-pole position of the movable contact at the time of current-limiting interruption by electromagnetic repulsive force is provided.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When providing a latch mechanism, a complicated configuration such as a rotating member having a cam surface and a spring for pressing a latch against a pin of the movable contact needs to be added, and a certain amount of space is required, making it difficult to apply to small-sized models. An object of the present invention is to be able to maintain the open-pole position of the movable contact at the time of current-limiting interruption with a simple structure in a circuit breaker and also to be applicable to small-sized models.

Means for Solving the Problems

[0005] A circuit breaker according to one aspect of the present invention comprises a fixed contact, a movable contact, a first magnetic material, and a second magnetic material. The fixed contact has a fixed contact formed thereon. The movable contact is rotatably supported, has a movable contact formed on its radially outward side, and rotation causes the movable contact to contact and separate from the fixed contact. The first magnetic material is provided between the movable contact and the pivot center of the movable contact. The second magnetic material is provided in the housing and faces the first magnetic material when the movable contact is open. The first magnetic material and the second magnetic material are attracted to each other by an electromagnetic repulsion force during a short circuit, which forms a magnetic path around the axis in the direction of current flow to the movable contact due to the arc when the movable contact is opened. [Effects of the Invention]

[0006] According to the present invention, when the movable contact opens due to the electromagnetic repulsive force caused by the short-circuit current, the first magnetic material and the second magnetic material are attracted to each other, thereby maintaining the open position during current limiting and interruption. The first magnetic material and the second magnetic material have a simple structure in which they form a magnetic path around the axis in the direction of current flow to the movable contact by the arc, making it applicable to small models as well. [Brief explanation of the drawing]

[0007] [Figure 1] This is a diagram showing a circuit breaker. [Figure 2] This is a diagram showing a fixed contactor. [Figure 3] This is a diagram showing a movable contact. [Figure 4] This figure shows the state when the electrodes are opened due to current limiting and blocking. [Figure 5] This is a diagram of cross-section AA in Figure 4. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings. Note that the drawings are schematic and may differ from actual examples. Furthermore, the following embodiments are illustrative examples of devices and methods for realizing the technical concept of the present invention, and do not limit the configuration to those described below. In other words, the technical concept of the present invention can be modified in various ways within the technical scope described in the claims.

[0009] 《Embodiment》 "composition" In the following explanation, the three mutually orthogonal directions will be referred to as the vertical direction, the width direction, and the depth direction for convenience. One of the vertical directions is the power supply side, and the other vertical direction is the load side. Figure 1 shows a circuit breaker 11. Here, the cross-sections along the vertical and depth directions are shown as viewed from one side in the width direction, and the illustrations of the opening / closing mechanism and operating handles are omitted for simplicity of explanation. The circuit breaker 11, also called a no-fuse breaker, automatically shuts off the circuit and protects against damage caused by overcurrent when it detects an abnormal overcurrent due to overload or short circuit. Each pole of the circuit breaker 11 is equipped with a fixed contact 12, a movable contact 13, a movable holder 14, a lead plate 15, a tripping device 16, and a terminal plate 17, and these are arranged in the width direction for the number of poles.

[0010] The fixed contact 12 is a strip-shaped conductor and is provided on one side of the case 21 in the vertical direction. The fixed contact 12 is formed in a crank shape when viewed from the width direction by bending, with one side in the vertical direction facing the front in the depth direction and the other side in the vertical direction facing the back in the depth direction. Figure 2 shows the fixed contactor 12. Figure (a) shows the fixed contact 12 viewed from the front in the depth direction. Figure (b) shows the fixed contact 12 viewed from the other in the vertical direction, one in the width direction, and the front in the depth direction. The fixed contact 12 has a terminal hole 31 formed on one side in the vertical direction, into which a screw terminal is fitted and the power supply circuit is connected. On the other side in the vertical direction of the fixed contact 12, a protruding piece 32 is formed by cutting and bending, which protrudes toward one side in the vertical direction, and a fixed contact 33 is formed on the front side in the depth direction of the protruding piece 32.

[0011] Returning to the explanation of Figure 1, the movable contact 13 is a rod-shaped conductor, with its base end rotatably supported by the movable holder 14. A movable contact 34 is formed on the radially outward tip side, and rotation causes the movable contact 34 to contact and separate from the fixed contact 33. The rotation direction that brings the movable contact 34 into contact with the fixed contact 33 is defined as the closing direction, and the rotation direction that separates the movable contact 34 from the fixed contact 33 is defined as the opening direction. Figure 3 shows the movable contact 13. Here, the movable contact 13 in the closed position is shown as viewed from the other side in the vertical direction, one side in the width direction, and from the front in the depth direction. The base end of the movable contact 13 is rotatably held in the movable holder 14 by a support shaft 35 inserted in the width direction, and is biased in the closed direction by a coil spring (not shown).

[0012] A magnetic body 41 (first magnetic body) is fixed to the movable contact 13 between the movable contact 34 at the tip and the pivot center at the base. The magnetic body 41 is, for example, an iron plate and is formed into a U-shape by bending, enclosing both sides in the axial direction and the closed pole side in the rotation direction of the movable contact 13. The magnetic body 41 can be fixed by any method, for example, by using adhesive, press-fitting, or fasteners. Here, the magnetic body 41 is configured to protrude from the outer surface of the movable contact 13, but it is not limited to this. Alternatively, a groove may be formed on the outer surface of the movable contact 13, and the magnetic body 41 may be fitted into it so that the magnetic body 41 does not protrude from the outer surface of the movable contact 13.

[0013] A magnetic body 42 (second magnetic body) is fixed to the middle cover 22 (housing) which is fixed to the case 21, and when the movable contact 13 is open, the magnetic body 42 is fixed to the magnetic body 41 which is opposite to the magnetic body 41. The magnetic body 42 is, for example, an iron plate and is formed in the shape of a flat plate that closes the open side in the rotational direction of the magnetic body 41. The magnetic body 42 can be fixed by any method, for example, by using adhesive, press-fitting, or fasteners. Here, a groove is formed on the inner circumferential surface of the middle cover 22 and the magnetic body 42 is fitted into it so that the magnetic body 42 does not protrude from the inner circumferential surface of the middle cover 22, but it is not limited to this. The magnetic body 42 may also be configured to protrude from the inner circumferential surface of the middle cover 22.

[0014] Figure (a) shows a movable contact 13 connected by wiring as one embodiment of an electrical connection method. A pair of short cylindrical connection ends 36 are formed at the base end of the movable contact 13, arranged in the width direction, and each connection end 36 is brazed to the opposing lead plate 15 by a lead wire (not shown). Figure (b) shows a movable contact 13 connected by sliding contact, representing another aspect of the electrical connection method. The base end of the movable contact 13 is in rotatable contact with a pair of connecting plates 37 aligned in the width direction. The connecting plates 37 are plate-shaped conductors, formed in a plate shape along the vertical and depth directions, with a support shaft 35 inserted in the width direction, sandwiching the movable contact 13. The rear end of the pair of connecting plates 37 in the depth direction is connected to a lead plate 15 extending in one direction in the vertical direction. Thus, the pair of connecting plates 37 become part of the current path.

[0015] Return to the description of FIG. 1. The movable holder 14 is made of resin, formed in a substantially cylindrical shape, and is rotatable between an insertion position and a cutoff position in conjunction with the opening / closing mechanism. The movable holders 14 arranged in the width direction for each pole are connected to each other, and the connecting portion thereof is held by the case 21 in a rotatable state. The tip side of the movable contact 13 protrudes from an opening formed on the cylindrical surface, and restricts the rotation of the movable contact 13 in the closing pole direction. When the movable holder 14 is in the insertion position rotated in the closing pole direction, rotation of the movable contact 13 in the opening pole direction at the closing pole position is allowed. When the movable holder 14 is in the cutoff position rotated in the opening pole direction, rotation of the movable contact 13 in the closing pole direction at the opening pole position is blocked.

[0016] The lead plate 15 is a plate-shaped conductor and is supported by the case 21. When connecting the movable contact 13 by a lead wire, the lead plate 15 is formed in an L shape when viewed from the width direction so as to face the connection end 36. On the other hand, when connecting the movable contact 13 by sliding contact, the lead plate 15 is formed in a substantially flat plate shape. The tripping device 16 is a general thermal type, and thus detailed description thereof is omitted. When the bimetal contacting the heater plate is curved by the Joule heat generated by an overcurrent, the trip lever is disengaged, and the movable holder 14 is rotated from the insertion position to the cutoff position via the opening / closing mechanism. The tripping device 16 is not limited to the thermal type, and may be an electromagnetic type or an electronic type. The terminal plate 17 is a plate-shaped conductor and is supported by the case 21. One side in the vertical direction of the terminal plate 17 is connected to the heater plate of the tripping device 16, and the load-side circuit is connected by fitting a screw terminal into the other side in the vertical direction.

[0017] FIG. 4 is a diagram showing a state of being opened by current-limiting interruption. When a short circuit occurs, the circuit breaker 11 becomes a current-limiting breaker that opens the pole by bouncing up the movable contact 13 by electromagnetic repulsive force before the tripping device 16 operates. As the principle of generating electromagnetic repulsive force, at the contact point between the fixed contact 33 and the movable contact 34, current concentration and diffusion occur, generating an electromagnetic repulsive force that tries to separate from each other by the current flowing in the reverse direction. Further, between the protruding piece 32 and the movable contact 13, when the current flows in the reverse direction, an electromagnetic repulsive force that also tries to separate from each other is generated. Due to such electromagnetic repulsive force, the movable contact 13 bounces up and opens the pole.

[0018] During current-limiting interruption, an arc generated between the fixed contact 33 and the movable contact 34 allows current to flow as shown by the thick solid line. Figure 5 is a view showing the A-A cross section of Figure 4. Here, in Figure 4, a cross section orthogonal to the energization direction flowing through the movable contact 13, passing through the movable contact 13, the magnetic body 41, and the magnetic body 42, is shown as viewed from the tip side of the movable contact 13. Since current flows from the front to the back on the paper surface through the movable contact 13, a clockwise magnetic path passing through the magnetic body 41 and the magnetic body 42 is formed according to the right-hand screw rule as shown by the thick dotted line, and the magnetic body 41 and the magnetic body 42 are attracted to each other.

[0019] 《Function and Effect》 Next, the main function and effect of the embodiment will be described. The circuit breaker 11 comprises a fixed contact 12, a movable contact 13, a magnetic material 41, and a magnetic material 42. The fixed contact 12 has a fixed contact 33 formed thereon. The movable contact 13 is rotatably supported, and has a movable contact 34 formed on its radially outward side, which moves into and out of contact with the fixed contact 33 by rotation. The magnetic material 41 is provided between the movable contact 34 and the pivot center of the movable contact 13. The magnetic material 42 is provided on the middle cover 22 and faces the magnetic material 41 when the movable contact 13 is open. The magnetic material 41 and the magnetic material 42 are attracted to each other by the electromagnetic repulsion force during a short circuit, which forms a magnetic path around the axis in the direction of current flow to the movable contact 13 by the arc when the movable contact 13 is open. As a result, when the movable contact 13 opens due to the electromagnetic repulsion force caused by the short-circuit current, the magnetic material 41 and magnetic material 42 are attracted to each other, thereby maintaining the open position during current limiting and interruption. In other words, it is possible to suppress the movable contact 13 from hitting the middle cover 22 and bouncing back, thus preventing it from closing again. Since the magnetic material 41 and magnetic material 42 have a simple structure that only forms a magnetic path around the axis in the direction of current flow to the movable contact 13 by the arc, it can be applied to small models as well, improving versatility.

[0020] The magnetic material 41 is formed in a U-shape, surrounding both sides of the movable contact 13 in the axial direction and the closed side in the rotational direction. The magnetic material 42 is formed in a flat plate shape, closing the open side in the rotational direction of the magnetic material 41. As a result, when the movable contact 13 opens due to the electromagnetic repulsion force during a short circuit, a magnetic path can be formed around the axis in the direction of current flow to the movable contact 13 by the arc. When a short-circuit current flows, the movable contact 13 opens due to electromagnetic repulsion before it trips. This enables current limiting and interruption. When the arc disappears, the attractive force of the magnetic materials 41 and 42 is also lost, but by then the tripping device 16 has already tripped, so the movable holder 14 maintains the open position of the movable contact 13. The circuit breaker 11 includes a connecting plate 37 that contacts the radially inner side of the movable contact 13 and forms a current-carrying path. Thus, this can also be applied to movable contacts 13 of the type in which the connecting plate 37 is provided on the radially inner side.

[0021] Next, we will explain the comparative examples. Previously, it had been considered to provide a latch mechanism to maintain the open position of the movable contact when the movable contact is flipped up by electromagnetic repulsion during current limiting and interruption. However, providing a latch mechanism would require the addition of a complex configuration, such as a rotating member with a cam surface and a spring that presses the latch against the pin of the movable contact, and would require a certain amount of space, making it difficult to apply to small models. Furthermore, since the latch mechanism is located radially on the inside of the movable contact, it was particularly difficult to apply to movable contacts 13 of the type that have a connecting plate 37 radially on the inside, as shown in Figure 3(b).

[0022] Variant form In this embodiment, a U-shaped magnetic material 41 is provided on the side of the movable contact 13 and a flat magnetic material 42 is provided on the side of the middle cover 22, but the invention is not limited to this. The point is that when the movable contact 13 opens due to the electromagnetic repulsion force during a short circuit, a magnetic path should be formed around the axis in the direction of current flow to the movable contact 13 by the arc. Therefore, the two can be swapped, with the flat magnetic material 42 provided on the side of the movable contact 13 and the U-shaped magnetic material 41 on the side of the middle cover 22.

[0023] Although the above description has been made with reference to a limited number of embodiments, the scope of the rights is not limited to those embodiments, and modifications of the embodiments based on the above disclosure will be obvious to those skilled in the art. [Explanation of symbols]

[0024] 11...Circuit breaker, 12...Fixed contact, 13...Movable contact, 14...Movable holder, 15...Lead plate, 16...Device, 17...Terminal plate, 21...Case, 22...Middle cover, 31...Terminal hole, 32...Protruding piece, 33...Fixed contact, 34...Movable contact, 35...Support shaft, 36...Connecting end, 37...Connecting plate, 41...Magnetic material, 42...Magnetic material

Claims

1. A fixed contactor with a fixed contact formed therein, A movable contact is rotatably supported, has a movable contact formed on its radially outward side, and rotates to bring the movable contact into contact with and separate from the fixed contact, A first magnetic material provided between the movable contact and the pivot center of the movable contact, The housing is provided with a second magnetic material which faces the first magnetic material when the movable contact opens, The first magnetic material and the second magnetic material are attracted to each other when the movable contact opens due to the electromagnetic repulsion force during a short circuit, as a magnetic path is formed around the axis in the direction of current flow to the movable contact by the arc. The first magnetic material is formed in a U-shape that surrounds both sides of the movable contact in the axial direction and the closed pole side in the rotational direction, the length of the legs surrounding both sides in the axial direction corresponds to the length of both sides of the movable contact in the axial direction, and is fixed to the outer circumferential surface of the movable contact. The circuit breaker is characterized in that the second magnetic material is formed in the shape of a flat plate that closes the open side in the rotational direction of the first magnetic material.

2. The circuit breaker according to claim 1, characterized in that the movable contact opens due to electromagnetic repulsion before tripping when a short-circuit current flows.

3. The circuit breaker according to claim 1, further characterized by comprising a connecting plate that contacts the radially inner side of the movable contact and forms an energizing path.

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