Circuit breaker

Abstract

To provide a circuit breaker capable of improving breaking performance by preventing arc gas generated in an arc-extinguishing chamber from escaping to the outside, and making a strong flow of the arc gas act as a force for pushing an arc into an arc-extinguishing device.SOLUTION: An arc-extinguishing chamber 19 provided in cases 2a, 2b houses an opening-closing contact 3 composed of a fixed contact 10 having a fixed contact 10a and a movable contact 11 having a movable contact 11a, a holder unit 12 rotatably supporting a base end of the movable contact, and an arc-extinguishing device 19 for extinguishing an arc generated between the fixed contact and the movable contact, and a holder case 18 of the holder unit has a mover opening 29 formed along a movable range of the movable contact, and has a shutter 30 for shielding the mover opening from the arc-extinguishing chamber side following the operation of the movable contact.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] The circuit breaker has a case that houses an opening / closing contact consisting of a fixed contactor with a fixed contact and a movable contactor with a movable contact, a holder that supports the base end of the movable contactor so that it can rotate freely, and an arc extinguishing device that extinguishes an arc that occurs between the fixed contactor and the movable contactor (for example, Patent Document 1).

[0003] During the current-limiting opening operation of the moving contact, an arc and arc gas are generated between the fixed and moving contacts. When the arc gas flows strongly toward the exhaust port of the arc extinguishing device, the arc comes into contact with the grid of the arc extinguishing device in a short time, causing the arc voltage to rise rapidly and improving the interrupting performance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-294511 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the holder described in Patent Document 1, a movable contact opening is formed along the movable range of the movable contact, but arc gas generated in the arc extinguishing chamber escapes to the outside through the movable contact opening that is open at a location other than the movable contact. If the arc gas in the arc extinguishing chamber escapes to the outside, the force pushing the arc into the arc extinguishing device (arc gas flow) weakens, and there is a risk of deterioration in interruption performance.

[0006] Therefore, the present invention aims to provide a circuit breaker that can improve interruption performance by preventing the arc gas generated in the arc extinguishing chamber from escaping to the outside and by having the flow of arc gas act as a force to push the arc into the inside of the arc extinguishing device. [Means for solving the problem]

[0007] In order to achieve the above object, a circuit breaker according to one embodiment of the present invention has an arc extinguishing chamber provided in a case, which houses an open / close contact consisting of a fixed contactor having a fixed contact and a movable contactor having a movable contact, a holder unit that rotatably supports the base end of the movable contactor, and an arc extinguishing device that extinguishes an arc generated between the fixed contactor and the movable contactor, and the holder case of the holder unit has a movable contactor opening formed along the movable contactor's range of motion, and is equipped with a shutter that follows the movement of the movable contactor to shield the movable contactor opening from the arc extinguishing chamber side. [Effects of the Invention]

[0008] The circuit breaker according to the present invention can improve the interruption performance by preventing the arc gas generated in the arc extinguishing chamber from escaping to the outside and by allowing the strong flow of the arc gas to act as a force pushing the arc into the inside of the arc extinguishing device. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a circuit breaker according to the present invention. [Figure 2] FIG. 2 is a perspective view showing a mover unit that constitutes a holder unit according to the present invention. [Figure 3] FIG. 2 is a perspective view showing a holder case constituting the holder unit according to the present invention. [Figure 4] FIG. 10 is a perspective view showing a state in which a shutter is fixed to a movable unit. [Figure 5] FIG. 2 is a perspective view showing a holder unit. [Figure 6] FIG. 10 is a cross-sectional view of a circuit breaker showing the initial current-limiting opening operation of the movable contact. [Figure 7] FIG. 10 is a perspective view showing the holder unit during the initial current-limiting opening operation of the movable contactor. [Figure 8] FIG. 10 is a cross-sectional view of a circuit breaker showing the terminal current-limiting opening operation of a movable contact. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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.

[0011] 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.

[0012] FIG. 1 is a cross-sectional view showing a first embodiment of a mechanical molded case circuit breaker 1 for three-phase (R, S, T) AC connected between the power supply side and the load side of a circuit, and shows the circuit structure of one of the phases assembled in parallel in a main body case 2.

[0013] The mechanical molded case circuit breaker 1 has, inside the main body case 2, a switching mechanism 4 that opens and closes the switching contacts 3, a switching handle 5 that operates the switching mechanism 4, an overcurrent tripping device 6 that causes the switching mechanism 4 to trip when an overcurrent flows in the main circuit, and an arc extinguishing device 7.

[0014] The main body case 2 is configured 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.

[0015] The switching contacts 3 are composed of a fixed contact 10 having a fixed contact 10a and a movable contact 11 having a movable contact 11a, and the movable contact 11 is rotatably supported by a holder unit 12. The fixed contact 10 is connected to a power supply side main circuit terminal 8, and the movable contact 11 is connected to a load side main circuit terminal 9 via a holder base 22 of the holder unit 12 and an overcurrent trip device 6.

[0016] The switching mechanism 4 is composed of a toggle link mechanism (not shown) that connects the movable contact 11 and the switching handle 5, a latch mechanism that combines a latch (not shown), and a trip crossbar 13. When the trip crossbar 13 rotates counterclockwise, the switching mechanism 4 trips, causing the movable contact 11 to perform an opening operation.

[0017] The overcurrent tripping device 6 is equipped with a heater 14 that heats up when an overcurrent flows between the power supply side main circuit terminal 8 and the load side main circuit terminal 9, a bimetal 15 fixed to the lower part of the heater 14, and an adjustment screw 16 that engages with the free end of the upper part of the bimetal 15 and can be moved back and forth to provide a predetermined gap between the bimetal 15 and the trip crossbar 13.

[0018] The lower case 2a and power supply side intermediate case 2b of the main body case 2 form an arc extinguishing chamber 19 that houses the switching contacts 3, the holder unit 12, and the arc extinguishing device 7. The cases described in the present invention correspond to the lower case 2a and the power supply side intermediate case 2b.

[0019] The arc extinguishing device 7 includes a plurality of grids 7a arranged in layers, and an exhaust port 7b that communicates with the outside on the end side spaced apart from the opening and closing contacts 3 of the plurality of grids 7a. The exhaust port 7b is covered with a protective plate 7c.

[0020] The holder unit 12 includes a mover unit 17 shown in FIG. 2 and a holder case 18 that houses the proximal end side of the mover unit 17 shown in FIG. 3.

[0021] As shown in FIG. 2, the mover unit 17 includes a holder base 22 having a connection plate 20 and a support portion 21, a mover rotation shaft 23 attached to the support portion 21 and rotatably supporting the movable contact 11, a mover contact pressure spring 24, and a pair of sliding contact pressure springs 25. The support portions 21 of the holder base 22 include a pair of plate-shaped sliding contacts 26, 27 extending parallel to each other, and a shaft hole (not shown) through which the mover rotation shaft 23 passes is formed. The pair of sliding contact pressure springs 25 disposed inside the holder case 18 are disposed on the outer surfaces of the pair of sliding contacts 26, 27 so as to surround the mover rotation shaft 23 and act with a spring force in a direction to closely contact the proximal end portion of the movable contact 11 in a surface contact state. Further, the mover contact pressure spring 24 disposed inside the holder case 18 acts on the movable contact 11 with a spring restoring force in the closing pole direction.

[0022] And protective covers 28 formed of synthetic resin are fixed to both side surfaces and the bottom surface on the movable contact 11a side of the movable contact 11.

[0023] As shown in FIG. 3, the holder case 18 is a substantially cylindrical member formed of an insulating material for mounting three-phase mover units 17 in parallel, and three mover openings 29 are formed at positions spaced apart in the longitudinal direction. The mover opening 29 is set to an opening width H2 larger than the thickness width H1 (see FIG. 2) of the movable contact 11 (H1 < H2), and is an opening extending along the circumferential direction.

[0024] FIG. 4 shows the state in which the shutter 30 is attached to the movable element unit 17. The shutter 30 is a synthetic resin plate that is curved in an arc shape in the longitudinal direction. The shutter 30 is formed with approximately the same curvature as the longitudinal opening periphery of the movable element opening 29 of the holder case 18 shown in FIG. 3, and has a shutter width H3 that is larger than the opening width H2 of the movable element opening 29 (H3>H2). The shutter 30 has a mounting through hole 30a formed in approximately the center in the longitudinal direction. In FIG. 4, the part of the shutter 30 above the mounting through hole 30a is referred to as an upper shutter portion 30b, and the part below the mounting through hole 30a is referred to as a lower shutter portion 30c.

[0025] This shutter 30 is inserted through the mounting through-hole 30a from the tip side (movable contact 11a) of the movable contactor 11, and then moved to the base end side of the movable contactor 11, and fixed to the movable contactor 11 at the base end side of the protective cover 28.

[0026] Next, Fig. 5 shows the holder unit 12 in which the shutter 30 is attached to the movable unit 17. Although Fig. 5 shows only one-phase movable unit 17, the other two-phase movable units 17 are also attached in the same manner.

[0027] 5 shows the holder unit 12 with the switch contact 3 in the ON state (the state in FIG. 1). At this time, the mover opening 29 of the holder case 18 is covered by the upper shutter portion 30b of the shutter 30.

[0028] 6 shows the initial current-limiting opening operation of the movable contact 11 when an overcurrent flows between the power-side main circuit terminal 8 and the load-side main circuit terminal 9 of the circuit breaker 1. At this time, an arc A1 and arc gas are generated between the fixed contact 10a and the movable contact 11a. As shown in FIG. 7, the movable contact opening 29 of the holder case 18 is shielded by the upper shutter portion 30b and the lower shutter portion 30c of the shutter 30, which moves with the opening operation of the movable contact 11, and the arc gas generated between the fixed contact 10a and the movable contact 11a is retained in the arc-extinguishing chamber 19.

[0029] 8 shows the final current-limiting opening operation of the movable contactor 11. Until the final current-limiting opening operation of the movable contactor 11, the movable contact opening 29 of the holder case 18 remains shielded by the upper shutter portion 30b and the lower shutter portion 30c of the shutter 30, which moves with the opening operation of the movable contactor 11. The arc gas does not escape from the movable contact opening 29 of the holder case 18 and remains in the arc extinguishing chamber 19. As the gas pressure increases, a strong flow G1 of arc gas is generated toward the exhaust port 7b. The strong flow G1 of arc gas then pushes the arc A1 into the multiple grits 7a arranged in layers, and the arc A1 comes into contact with the multiple grits 7a in a short time, causing a rapid rise in arc voltage.

[0030] Therefore, this embodiment prevents the arc gas generated in the arc extinguishing chamber 19 from escaping to the outside of the arc extinguishing chamber 19, and the strong flow of the arc gas acts as a force to push the arc into the multiple grids 7a of the arc extinguishing device 7, thereby rapidly increasing the arc voltage and improving the interruption performance.

[0031] In addition, by fixing a shutter 30 to the movable contact 11 and rotating the shutter in response to the opening operation of the movable contact 11, the movable contact opening 29 in the holder case 18 is constantly shielded, thereby reliably preventing arc gas from escaping from the arc extinguishing chamber 19.

[0032] Furthermore, since the shutter 30 is formed in an arc shape that slides on the outer peripheral surface of the cylindrical shape of the holder case 18, it can perform a smooth shielding operation for the movable element opening 29. [Explanation of symbols]

[0033] 1 Mechanical wiring circuit breaker 2 Main unit case 2a Lower case 2b Power supply side 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 7a Grid 7b Exhaust port 7c Protective plate 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 Holder unit 13 Trip Crossbar 14 Heater 15 Bimetal 16 Adjustment screw 17 Movable unit 18 Holder case 19 Arc room 20 Connection plate 21 Support part 22 Holder base 23 Mover rotation axis 24. Movable contact spring 25 Sliding contact pressure spring 26,27 Sliding contact 28 Protective cover 29 Mover opening 30 Shutter 30a Mounting through hole 30b Upper shutter part 30c Lower shutter part A1 Arc G1 Strong flow of arc gas

Claims

1. The case accommodates an open / close contact configured with a fixed contactor having a fixed contact and a movable contactor having a movable contact, a holder unit that rotatably supports a base end of the movable contactor, and an arc extinguishing device that extinguishes an arc generated between the fixed contactor and the movable contactor, a holder case of the holder unit is formed with a movable contact opening along a movable range of the movable contact, A circuit breaker comprising: a shutter that follows the movement of the movable contactor to shield the movable contactor opening from the arc extinguishing device side.

2. 2. The circuit breaker according to claim 1, wherein the shutter is fixed to a part of the movable contactor that protrudes from the movable contactor opening to the outside of the holder case.

3. 3. The circuit breaker according to claim 1, wherein the outer peripheral surface of the holder case that forms the armature opening is cylindrical, and the shutter is an arc-shaped member that slides on the outer peripheral surface.

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