Circuit breaker

Abstract

To provide a circuit breaker which can reduce an external arc space.SOLUTION: A circuit breaker includes a stator 22 having a stationary contact point 22a, a mover 23 having a movable contact point 23a movable when a circuit on a power supply side relative to the stator 22 and a circuit on a load side are connected or interrupted, and an arc-extinguishing chamber 24 having a grid 25 for arc-extinguishing an arc 2 generated at the time of current interruption and an exhaust port 4 for exhausting hot gas generated from the arc 2, wherein a resin structure 5 composed of a resin material is arranged outside the exhaust port 4 and an internal exhaust path 12 of the hot gas is formed, and a metal structure 19 composed of a metal material is arranged on the downstream side of the internal exhaust path 12.SELECTED DRAWING: Figure 2

Description

【Technical Field】 【0001】 The present invention relates to a circuit breaker capable of reducing the size of an external arc space. 【Background Art】 【0002】 In a circuit breaker, the hot gas generated from an arc at the time of interruption contains vaporized gas of electrode material and metal grid for arc extinction, so it is a conductive high-temperature gas. In a circuit breaker, in order to achieve interruption and suppress the increase in internal pressure of the interruption chamber, it is necessary to exhaust the conductive hot gas to the outside of the circuit breaker through an exhaust port. Here, if the conductive gas exhausted from the circuit breaker comes into contact with a charged metal terminal, there is a possibility of developing into a ground fault or short-circuit accident. For this reason, in a circuit breaker, it is necessary to secure an arc space outside so as to sufficiently cool the temperature of the hot gas and further sufficiently diffuse the metal vapor, which is a conductive substance, to reduce the conductivity of the gas. 【0003】 In addition, Patent Document 1 describes a structure having a double structure in which the inside of the base is formed of an organic-inorganic composite composition and the outside is formed of a structural composition such as a thermosetting resin. When the electrodes are opened and closed, an arc is generated between the contacts of the electrodes, and the free carbon generated from the organic material of the internal structure, the metal vapor and molten metal droplets generated from the metal parts of the internal structure by this generated arc are insulated by an insulating gas generated from an inorganic compound that undergoes a dehydration reaction at 150 °C or higher contained in the inner organic-inorganic composite composition. Thereby, a decrease in the electrical resistance of the inner surface of the base is prevented, and the insulation performance after electrode opening and closing between the electrodes of the switch is improved. 【0004】 Further, Patent Document 2 proposes a structure in which the conductive hot gas exhausted from the circuit breaker is brought into contact with a resin structure, and the conductivity is reduced together with the temperature of the hot gas by mixing an insulating low-temperature gas (ablation gas) from the resin into the hot gas. 【Prior Art Documents】 【Patent Documents】 【0005】 [Patent Document 1] Japanese Patent Publication No. 2001-357769 [Patent Document 2] Japanese Patent Publication No. 2017-103005 [Overview of the Initiative] [Problems that the invention aims to solve] 【0006】 Incidentally, conventional circuit breakers, as mentioned above, required a large arc space outside to reduce the temperature and conductivity of the discharged hot gas. In devices incorporating such circuit breakers, such as switchboards, the need to secure a large arc space hinders the miniaturization of the device. 【0007】 On the other hand, Patent Document 2 describes a method for miniaturizing the arc space by placing a resin structure outside the exhaust port of a circuit breaker. When heat is absorbed into the resin from a hot gas above the resin's decomposition temperature, an insulating low-temperature gas (ablation gas) from the resin is mixed into the hot gas, thereby reducing the conductivity along with the temperature of the hot gas. However, if the structure is constructed solely of resin, it is difficult to lower the hot gas temperature below the resin's decomposition temperature, making it impossible to achieve sufficient temperature reduction and conductivity reduction. This is because the low thermal conductivity of the resin inhibits heat absorption into the resin. 【0008】 The present invention has been made in view of the above, and aims to provide a circuit breaker that can reduce the external arc space. [Means for solving the problem] 【0009】 To solve the above-mentioned problems and achieve the objective, the circuit breaker according to the present invention comprises a stator having fixed contacts, a movable element having movable contacts that move when connecting or disconnecting a power supply side circuit and a load side circuit with respect to the stator, and an arc extinguishing chamber having a grid for extinguishing an arc generated when current is interrupted and an exhaust port for discharging hot gas generated from the arc, wherein a resin structure made of a resin material is arranged outside the exhaust port to form an exhaust passage for the hot gas, and a metal structure made of a metal material is arranged downstream of the exhaust passage. 【0010】 Furthermore, the circuit breaker according to the present invention is characterized in that the resin structure and the metal structure forming the exhaust passage are in a labyrinth structure. 【0011】 Furthermore, the circuit breaker according to the present invention is characterized in that the inner wall surface of the labyrinth structure has a diffusion structure in which a plurality of grooves parallel to the flow of the hot gas are formed. 【0012】 Furthermore, the circuit breaker according to the present invention is characterized in that, in the above invention, the minimum flow path cross-sectional area of ​​the exhaust flow path is larger than the flow path cross-sectional area of ​​the exhaust port. [Effects of the Invention] 【0013】 According to the present invention, a resin structure made of resin material is placed outside the exhaust port of the arc extinguishing chamber, and hot gas above the resin decomposition temperature is efficiently cooled by the generation of resin ablation gas. Furthermore, by utilizing the high thermal conductivity of metal through a metal structure made of metal material placed downstream of the flow path, cooling and conductivity reduction are achieved by heat absorption down to low temperatures, thereby enabling a reduction in the external arc space and miniaturization of the device into which the circuit breaker is incorporated. [Brief explanation of the drawing] 【0014】 [Figure 1]FIG. 1 is a perspective view showing the overall structure of the circuit breaker according to Embodiment 1 of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing the configuration near the exhaust port of the arc extinguishing chamber. [Figure 3] FIG. 3 is a perspective view of the resin structure arranged outside the exhaust port of the arc extinguishing chamber as viewed obliquely upward from the upper right front. [Figure 4] FIG. 4 is a broken view of the resin structure as viewed obliquely upward from the upper right rear. [Figure 5] FIG. 5 is a broken view of the internal structure of the resin structure as viewed obliquely downward from the upper right front. [Figure 6] FIG. 15 is a schematic diagram showing the cross-sectional structure of the resin structure and the flow of hot gas. [Figure 7] FIG. 7 is a perspective view of the resin structure provided in the circuit breaker according to Embodiment 2 as viewed obliquely upward from the upper right front. [Figure 8] FIG. 8 is a broken view of the internal structure of the resin structure shown in FIG. 7 as viewed obliquely upward from the upper right rear. [Figure 9] FIG. 9 is a broken view of the internal structure of the resin structure shown in FIG. 7 as viewed obliquely downward from the upper right front. [Figure 10] FIG. 10 is a schematic diagram showing the cross-sectional structure of the resin structure shown in FIG. 7 and the flow of hot gas. 【Mode for Carrying Out the Invention】 【0015】 Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. 【0016】 (Embodiment 1) FIG. 1 is a perspective view showing the overall structure of the circuit breaker 1 according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view showing the configuration near the exhaust port 4 of the arc extinguishing chamber 24. FIG. 3 is a perspective view of the resin structure 5 disposed outside the exhaust port 4 of the arc extinguishing chamber 24 as viewed obliquely upward from the right front. FIG. 4 is a broken view of the resin structure 5 as viewed obliquely upward from the right rear. FIG. 5 is a broken view of the internal configuration of the resin structure 5 as viewed obliquely downward from the right front. FIG. 6 is a schematic diagram showing the cross-sectional structure of the resin structure 5 and the flow of the hot gas 3. 【0017】 As shown in FIGS. 1 and 2, the circuit breaker 1 includes a stator 22 having a fixed contact 22a and a rotor 23 having a movable contact 23a. The rotor 23 moves when connecting or disconnecting a circuit on the power supply side (not shown) and a circuit on the load side (not shown) with respect to the stator 22. The arc extinguishing chamber 24 has a grid 25 and an exhaust port 4. The grid 25 is for interrupting and cooling the arc 2 generated at the time of current interruption to extinguish the arc. The exhaust port 4 is disposed at a position facing the generation position of the arc 2 through the grid 25, and discharges the hot gas generated from the arc 2. 【0018】 In the resin structure 5, a flow path indicated by an internal exhaust path 12 is formed which is disposed outside the exhaust port 4 and exhausts the hot gas flowing in from the exhaust port 4 through the hot gas inlet 18 to the outside of the circuit breaker 1 from the resin structure exhaust port 11. The resin structure 5 is formed of a resin material that generates an insulating gas at a temperature lower than the decomposition temperature by contact with the hot gas, and is formed of, for example, PA6 or POM. 【0019】 Further, a metal structure 19 is disposed on the internal exhaust path 12 on the downstream side of the contact surface between the resin structure 5 and the hot gas. Even in the case of contact with the hot gas whose temperature has been lowered by the resin, by utilizing the high thermal conductivity of the metal, the temperature of the hot gas can be lowered to a lower temperature than when only the resin structure 5 is disposed. 【0020】 As shown in Figures 2 to 5, the resin structure 5 has a labyrinth structure in which the flow path indicated by the internal exhaust path 12 is a zigzag flow path from the hot gas inlet 18 to the resin structure exhaust port 11. To form this labyrinth structure, a resistance plate 13 is provided between the hot gas inlet 18 and the resin structure exhaust port 11 to prevent the hot gas from flowing in linearly from the hot gas inlet 18 and to divert the hot gas exhaust path. In addition, the minimum flow path cross-sectional area of ​​the labyrinth structure is larger than the flow path cross-sectional area of ​​the exhaust port 4 of the circuit breaker 1. 【0021】 Here, with reference to Figure 6, the effect of the resin structure 5 and the metal structure 19 on reducing the temperature and conductivity of the hot gas will be explained. First, when the circuit breaker 1 is tripped, hot gas 3 containing metal vapor is released from the exhaust port 4 from the arc 2 generated. The hot gas 3 that flows in from the hot gas inlet 18 flows into the flow path shown in the internal exhaust path 12. Heat exchange occurs at the interface between the incoming hot gas 3 and the resin of the resin structure 5, especially the resin of the resistance plate 13, and heat absorption 6 occurs from the hot gas 3. The temperature of the hot gas 3 decreases due to this heat absorption 6. As the temperature decreases, the metal vapor contained in the hot gas 3 liquefies on the resin surface, then solidifies, and as a result is adsorbed onto the resin. Furthermore, on the resin surface, ablation gas 9, which is a thermal decomposition gas of the highly insulating resin, is generated due to the heat input from the hot gas 3. Since this ablation gas 9 is a gas with a temperature lower than the freezing point of the metal, it mixes with the hot gas 3, and the hot gas temperature decreases to a level equivalent to the decomposition temperature of the resin. Furthermore, the hot gas 3 is converted into a low-conductivity gas 8, whose conductivity has decreased, by the adsorption of metal vapor 7. 【0022】 Furthermore, the low-conductivity gas 8, which is at a temperature equivalent to the resin decomposition temperature, comes into contact with the metal structure 19 located downstream. This contact causes heat exchange with the low-conductivity gas 8 at the interface with the metal structure 19, resulting in heat absorption 20 from the low-conductivity gas 8. Since metals have a higher thermal conductivity than resins, heat is transferred from the metal surface to the interior of the metal by thermal conduction, lowering the temperature of the metal surface. Therefore, heat absorption is possible even for gases at relatively low temperatures below the resin decomposition temperature, and the low-conductivity gas 8 is converted into a mixed gas 10 at an even lower temperature. 【0023】 Generally, as the temperature of a gas decreases, its conductivity also decreases. Therefore, the mixed gas 10 has even lower conductivity compared to the low-conductivity gas 8. This mixed gas 10 is discharged into the outside space through the exhaust port 11 of the resin structure. Consequently, the hot gas 3 is blown onto the resin structure 5 and the metal structure 19, efficiently reducing its temperature and conductivity before being discharged into the outside space. 【0024】 As a result, it is possible to achieve both a reduction in the arc space that needs to be secured externally and an improvement in safety. In other words, the large arc space that would otherwise need to be secured is replaced by the space of the small resin structure 5 and the metal structure 19. Furthermore, since the device such as a switchboard into which the circuit breaker 1 of this embodiment 1 is incorporated does not need to secure this large arc space, the device can be made smaller. 【0025】 In particular, by making the resin structure 5 a labyrinth structure, the contact area between the hot gas 3 and the resin and metal is increased, which efficiently reduces the temperature and conductivity of the hot gas 3. Furthermore, this labyrinth structure causes pressure loss in the hot gas 3, suppressing its flow velocity. Additionally, since the flow path cross-sectional area of ​​the labyrinth structure is larger than that of the exhaust port 4, this also helps to suppress the flow velocity of the hot gas 3. As a result, the arc space that needs to be secured outside the circuit breaker 1 can be further reduced. 【0026】 (Embodiment 2) Figure 7 is a perspective view of the resin structure 5 provided in the circuit breaker 1 of this second embodiment, viewed from the upper right front. Figure 8 is a broken view of the internal structure of the resin structure 5 shown in Figure 7, viewed from the upper right rear. Figure 9 is a broken view of the internal structure of the resin structure 5 shown in Figure 7, viewed from the lower right front. Figure 10 is a schematic diagram showing the cross-sectional structure and hot gas flow of the resin structure 5 shown in Figure 7. 【0027】 In this second embodiment, as shown in Figures 7 to 10, compared to the configuration of the first embodiment, a plurality of grooves parallel to the flow of hot gas 3 are formed on the inner wall surface of the labyrinth structure, and a diffusion structure 14 made of resin and a diffusion structure 21 made of metal are provided, with a cross section perpendicular to the flow of hot gas having an uneven shape. 【0028】 The diffusion structure 14 of the resin structure and the diffusion structure 21 of the metal structure can increase the contact area between the resin and metal and the hot gas 3, and can further promote heat exchange between the resin and metal and the hot gas 3. 【0029】 Furthermore, as shown in Figure 10, the diffusion structure guide gas 17 cooled on the respective surfaces of the diffusion structure 14 of the resin structure and the diffusion structure 21 of the metal structure is guided like an air curtain by the guiding function of the respective diffusion structures 14 and 21, and is blown toward the bend 15 of the flow path shown in the internal exhaust path 12. This blowing causes thermal diffusion of the hot gas 3 passing through the center of the flow path at the bend 15, and also promotes heat absorption by the resin surface and metal surface to which it is blown. This blowing further promotes the cooling of the hot gas 3. For example, near the exhaust port 11 of the resin structure, the heat-exchanged hot gas 3 is exhausted along the diffusion structures 14 and 21 as a mixed gas 10 with low temperature and thermal conductivity. 【0030】 Therefore, in this second embodiment, the temperature and conductivity of the hot gas 3 can be efficiently reduced, and the external arc space can be further reduced. 【0031】 Furthermore, in the embodiments 1 and 2 described above, by making the minimum flow path cross-sectional area of ​​the labyrinth structure larger than the flow path cross-sectional area of ​​the exhaust port 4, the internal pressure rise can be made to be about the same as the internal pressure rise due to the arc 2 during interruption when the resin structure 5 is not provided, thereby preventing damage to the housing of the circuit breaker 1 due to the rise in internal pressure. 【0032】 Furthermore, the configurations illustrated in the embodiments described above are functional schematics and do not necessarily have to be physically represented as shown. In other words, the forms of distribution and integration of each device and component are not limited to those shown, and all or part of them can be functionally or physically distributed and integrated in any unit according to various usage situations. [Explanation of Symbols] 【0033】 1 Circuit breaker 2 Arc 3 Hot gas 4 exhaust ports 5 Resin structure 6.20 Heat absorption 7 Adsorption 8. Low-conductivity gases 9 Ablation gas 10 Mixed gas 11 Exhaust port for resin structure 12 Internal exhaust path 13 Resistance plate 14,21 Diffusion structure 15. Flexed section 17 Diffusion Structure Guide Gas 18 Hot gas inlet 19 Metal structures 22 Stator 22a Fixed contact 23 Mover 23a Movable contact 24 Arc Extinguishing Room 25 grid

Claims

[Claim 1] A circuit breaker comprising a stator having fixed contacts, a movable element having movable contacts that move when connecting or disconnecting a power supply circuit and a load circuit relative to the stator, and an arc extinguishing chamber having a grid for extinguishing an arc generated when current is interrupted and an exhaust port for discharging hot gas generated from the arc, A resin structure made of resin material is placed on the outside of the exhaust port. The resin structure has an exhaust channel that exhausts the hot gas flowing in from the exhaust port to the outside through the exhaust port of the resin structure. A plate-shaped metal structure made of metal material is placed downstream of the exhaust passage. The resin structure forming the exhaust passage is a labyrinth structure. The circuit breaker is characterized in that the metal structure does not cover the exhaust port of the resin structure, but its entire back surface is in surface contact with the resin structure, forming the inner wall surface of the hot gas exhaust passage. [Claim 2] The circuit breaker according to claim 1, characterized in that the exhaust port of the resin structure in the exhaust passage is open to the outside so as to allow exhaust. [Claim 3] The circuit breaker according to claim 2, characterized in that the inner wall surface of the labyrinth structure has a diffusion structure in which a plurality of grooves parallel to the flow of the hot gas are formed. [Claim 4] The circuit breaker according to any one of claims 1 to 3, characterized in that the minimum cross-sectional area of ​​the exhaust flow path is greater than the cross-sectional area of ​​the exhaust port.

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