Circuit interrupter

A circuit interrupter includes a fixed terminal, a movable contactor, a moving mechanism, a squib, and accommodation. The fixed terminal includes a fixed contact. The movable contactor includes a movable contact connected to the fixed contact. The moving mechanism is configured to move the movable contactor from a closed position where the movable contact is connected to the fixed contact to an open position where the movable contact is separated from the fixed contact. The squib is configured to generate gas by combustion. The accommodation is for accommodating the fixed contact and the movable contactor. In the circuit interrupter, the gas is introduced into the accommodation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/JP2019/011418 filed Mar. 19, 2019, claiming priority to Japanese Patent Application No. JP2018-063264 filed on Mar. 28, 2018, the content of each noted application is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure generally relates to circuit interrupters and in particular to a circuit interrupter for interrupting a circuit where a current flows.

BACKGROUND ART

Patent Literature 1 discloses a breaker including a pyrotechnic actuator which is intended to be mounted on an automobile, in particular, an electric vehicle.

The breaker of Patent Literature 1 includes a conductor, a housing, a matrix, a punch, and a pyrotechnic actuator.

The housing is partially intersected by the conductor. Opposite ends of the conductor serve as two connection terminals for the breaker. The matrix and the punch are placed on opposite sides (upper and lower sides) of the conductor.

The pyrotechnic actuator moves the punch from a first position to a second position when ignited. In movement of the punch from the first position to the second position, the punch, and the matrix break (chop) the conductor. The punch includes a groove. While the punch is in the second position, the groove of the punch is engaged with the matrix. Thereby, a space inside the housing is partitioned into two cutoff chambers.

When the punch moves from the first position to the second position and cuts the conductor, an electric arc may be formed. This electric arc travels a pathway between the cutoff chamber and a bottom of the groove of the punch. To increase a voltage of the electric arc, provided to a vicinity of the pathway is a material pulled out by ablation due to the electric arc.

In interrupters such as breakers, it is desired to extinguish an arc rapidly.

CITATION LIST

Patent Literature

Patent Literature 1 JP 2017-507469 A

SUMMARY OF INVENTION

In view of the above insufficiency, an object of the present disclosure would be to propose a circuit interrupter capable of extinguishing an arc quickly when the arc is developed.

A circuit interrupter according to one aspect of the present disclosure includes a fixed terminal, a movable contactor, a moving mechanism, a squib, and accommodation. The fixed terminal includes a fixed contact. The movable contactor includes a movable contact connected to the fixed contact. The moving mechanism is configured to move the movable contactor from a closed position where the movable contact is connected to the fixed contact to an open position where the movable contact is separated from the fixed contact. The squib is configured to generate gas by combustion. The accommodation is for accommodating the fixed contact and the movable contactor. The gas is introduced into the accommodation.

A circuit interrupter according to another aspect of the present disclosure includes a fixed terminal, a movable contactor, an excitation coil, and a moving mechanism. The fixed terminal includes a fixed contact. The movable contactor includes a movable contact connected to the fixed contact. The squib is configured to generate gas by combustion. The excitation coil is configured to move the movable contactor from a closed position where the movable contact is connected to the fixed contact to a first open position where the movable contact is separated from the fixed contact. The moving mechanism is configured to move the movable contactor to a second open position where the movable contact is separated from the fixed contact.

Advantageous Effects of Invention

According to the present disclosure, it is possible to extinguish an arc quickly when the arc is developed.

DESCRIPTION OF EMBODIMENTS

Embodiments and variations described below are some of example of the present disclosure. Various modifications may be made to the above-described embodiment and variations depending on design and the like as long as the object of the present disclosure can be achieved. Figures referred to in the following embodiments and variations are schematic, and there is no guarantee that ratios regarding sizes and thicknesses of components shown in the figures reflect actual ratios.

A circuit interrupter (current interrupter)100according to embodiment 1 will be described with reference toFIGS. 1-7.

The circuit interrupter100according to embodiment 1 includes, as shown inFIG. 1, a first fixed terminal (fixed terminal)1, a second fixed terminal2, a movable contactor (movable terminal)3, a holding unit4, a pyroactuator5, and an accommodation70.

The first fixed terminal1includes a first fixed contact (fixed contact)11. The first fixed terminal1includes a first electrode12to be connected to a first end of electric circuitry.

The second fixed terminal2includes a second fixed contact21. The second fixed terminal2includes a second electrode22to be connected to a second end of the electric circuitry.

The movable contactor3includes a first movable contact (movable contact)31. The first movable contact31is connected to the first fixed contact11. The movable contactor3includes a second movable contact32. The second movable contact32is connected to the second fixed contact21. In the present embodiment, the movable contactor3is formed as a separate part from each of the first fixed terminal1and the second fixed terminal2.

The first fixed contact11, the second fixed contact21, and the movable contactor3(the first movable contact31and the second movable contact32) are accommodated in the accommodation70.

The holding unit4holds the movable contactor3so that the first movable contact31is connected to the first fixed contact11and the second movable contact32is connected to the second fixed contact21. In particular, the holding unit4holds the movable contactor3so that the first movable contact31and the second movable contact32are connected to the first fixed contact11and the second fixed contact21, respectively, while no current flows through the movable contactor3(during a non-conduction state).

Hereinafter, a position of the movable contactor3where the first movable contact31is connected to the first fixed contact11is referred to as a closed position. In the closed position, the second movable contact32is connected to the second fixed contact21, too.

As shown inFIG. 1, the pyroactuator5includes a squib51, a case52, and a piston53.

The squib51is accommodated in the case52. The squib51is configured to generate gas by combustion. The squib51includes a heating element and an explosive (fuel). When the heating element is supplied with an electric signal, the heating element generates heat and then the explosive ignites. When the squib51is ignited, the explosive combusts to generate gas. The gas generated by the squib51has electrically insulating properties. Examples of the gas generated by the squib51may include a carbon monoxide gas, a carbon dioxide gas, and a nitrogen gas. The gas generated by the squib51is introduced into the pressurized chamber520to increase the pressure in the pressurized chamber520. In summary, the pressurized chamber520receives the pressure of the gas generated by the squib51.

The piston53receives pressure in the pressurized chamber520with its first end531and then is moved. The piston53applies a force in a direction away from the fixed terminal (the first fixed terminal)1to the movable contactor3(directly or indirectly) with its second end532to cause movement of the movable contactor3. More specifically, the piston53receives the pressure of the pressurized chamber520with the first end531and is pressed by the increased pressure in the pressurized chamber520to press the movable contactor3with the second end532. The piston53receives a large pressure in the pressurized chamber520and moves in a direction away from the squib51(a downward direction inFIG. 1) at a high speed to press the movable contactor3. The pressure in the pressurized chamber520presses the piston53from a first position (a position shown inFIG. 1) to a second position (a position shown inFIG. 7). Movement of the piston53from the first position to the second position expands the pressurized chamber520(a space inside the case52pressure of which is increased by introduction of the gas of the squib51).

The movable contactor3is pressed by the piston53and then moves within the accommodation70. As shown inFIGS. 6-7, the movable contactor3is pressed by the piston53and therefore the first movable contact31is separated from the first fixed contact11and the second movable contact32is separated from the second fixed contact21. Thus, an electric circuit between the first electrode12and the second electrode22is interrupted. As described above, in the present embodiment, the pressurized chamber520and the piston53function as a moving mechanism configured to move the movable contactor3from a position where the movable contact (first movable contact)31is connected to the fixed contact (first fixed contact)11to a position where the movable contact is separated from the fixed contact.

Hereinafter, a position of the movable contactor3where the first movable contact31is most separated from the first fixed contact11is referred to as an open position (a position of the movable contactor3shown inFIG. 7). In the open position, the second movable contact32is separated from the second fixed contact21, too.

As shown inFIG. 1, there is a channel50provided to the side wall of the case52. The channel50interconnects the inside and the outside of the case52. The channel50includes a first end501connected to the accommodation70and a second end502connected to the inside space of the case52. However, while the piston53is in the first position, the second end502of the channel50is not connected to the pressurized chamber520(seeFIG. 1).

Movement of the piston53from the first position (seeFIG. 1) to the second position (seeFIG. 7) extends the pressurized chamber520, thereby allowing the second end502of the channel50to be connected to the pressurized chamber520. As a result, the pressurized chamber520and the accommodation70are interconnected by the channel50. Therefore, the gas generated by the squib51is introduced into the accommodation70through the pressurized chamber520and the channel50.

The first fixed contact11and the first movable contact31are accommodated in the accommodation70. Here, as described above, the gas generated by the squib51is introduced into the accommodation70Thus, the arc generated between the fixed contact (first fixed contact)11and the movable contact (first movable contact)31(i.e., the arc generated in the predetermined space S1) is cooled by the gas generated in the squib51. The term “cooling of the arc” as used herein means to enhance the insulating properties of the plasma of the arc discharge or the metal vapor. For example, cooling of the arc can be achieved by increasing the pressure of the predetermined space S1by introduction of electrically insulating gas, blowing the arc with electrically insulating gas, or the like. When the arc is cooled, an electric field strength of the arc (a voltage per unit length) is increased. This can reduce the length of the arc that is possibly developed when a certain constant voltage is applied across the arc. Thereby, arc extinction can be promoted.

Thus, in the circuit interrupter100, when the movable contact (first movable contact)31is pulled away from the fixed contact (first fixed contact)11, the gas generated by the squib51is introduced into the accommodation70(in detail, the predetermined space S1). When the arc is developed between the contacts, the arc is cooled by the gas. Accordingly, the circuit interrupter100can quickly extinguish the arc.

Hereinafter, the circuit interrupter100according to the present embodiment will be described in detail with reference toFIGS. 1-7.

(1.2.1) Power Supply System

As shown inFIG. 5, the circuit interrupter100of the present embodiment is used, for example, as a fuse in the power supply system200.

The power supply system200, for example, is mounted on a vehicle300such as an electric vehicle and drives a motor3002connected via an inverter3001to allow the vehicle300to run. In the vehicle300, as shown inFIG. 5, a precharge capacitor3003is connected in parallel with the inverter3001.

In power transfer, the inverter3001converts DC power supplied from the power supply system200into AC power and supplies it to the motor3002. In power regeneration, the inverter3001converts AC power supplied from the motor3002into DC power and supplies it to the power supply system200. The motor3002is, for example, a three-phase AC synchronous motor.

The power supply system200includes a battery201, a first main relay202, a second main relay203, a precharge resistor204, a precharge relay205, a current sensor (shunt resistor)206, and control circuitry207in addition to the circuit interrupter100.

The battery201includes a plurality of battery cells connected in series. Examples of the battery cells may include nickel metal hydride battery cells and lithium ion battery cells.

The first main relay202includes a first end connected to a positive electrode of the battery201and a second end connected to a first input terminal (high potential side input terminal) of the inverter3001.

The second main relay203includes a first end connected to a negative electrode of the battery201through the current sensor206and the circuit interrupter100and a second end connected to a second input terminal (low potential side input terminal) of the inverter3001.

A series circuit of the precharge resistor204and the precharge relay205is connected in parallel with the first main relay202.

The control circuitry207controls operations of the first main relay202, the second main relay203, the precharge relay205, and the circuit interrupter100.

When power supply to the motor3002is started, the control circuitry207closes the precharge relay205and the second main relay203to charge the precharge capacitor3003. Thus, inrush current to the motor3002is suppressed. After completion of charging of the precharge capacitor3003, the control circuitry207opens the precharge relay205and closes the first main relay202to start power supply from the power supply system200.

The control circuitry207also detects occurrence of an abnormality in circuitry including the power supply system200based on a current detected by the current sensor206. When an abnormality occurs in the circuitry including the power supply system200, the control circuitry207operates (activates) at least one of the first main relay202, the second main relay203, and the circuit interrupter100to interrupt the circuitry.

The control circuitry207opens at least one of the first main relay202and the second main relay203when, for example, time in which the magnitude of the current detected by the current sensor206exceeds a first threshold value continues for first time. Thereby the circuitry is interrupted. In this case, for example, when the opened relay (the first main relay202and/or the second main relay203) is closed again by the control circuitry207, the circuitry is made again and therefore the power supply from the power supply system200to the motor3002is resumed.

On the other hand, for example, when time in which the magnitude of the current detected by the current sensor206exceeds a second threshold value (>the first threshold value) continues for second time, the control circuitry207operates the circuit interrupter100. Thereby, the circuitry is interrupted. The circuit interrupter100is a breaker for breaking an electrical circuit (path) of circuitry. The circuit interrupter100continues to break the electric circuit once operated (activated). After activation of the circuit interrupter100, the power supply from the power supply system200to the motor3002is stopped. Therefore, in the event of an accident or the like of the vehicle300, operation of the circuit interrupter100can separate the power supply system200.

Next, the configuration of the circuit interrupter100will be described with reference toFIGS. 1-4.

As described above, the circuit interrupter100includes the first fixed terminal1, the second fixed terminal2, the movable contactor3, the holding unit4, and the pyroactuator5. Further, as shown inFIG. 1, the circuit interrupter100includes a first yoke (lower yoke)61, a second yoke (upper yoke)62, and a housing7including the accommodation70.

The movable contactor3of the present embodiment is a plate member made of a metallic material with electrical conductivity and is formed to have length in one direction. The movable contactor3includes the first movable contact31and the second movable contact32at respective first and second ends in its length direction. The first fixed terminal1and the second fixed terminal2are arranged side by side along the length direction of the movable contactor3. The first fixed terminal1includes the first fixed contact11at a position facing the first movable contact31of the movable contactor3and the second fixed terminal2includes the second fixed contact21at a position facing the second movable contact32of the movable contactor3.

Hereinafter, for convenience of explanation, an upward/downward direction defines a direction in which the first fixed contact11and the first movable contact31face each other (a direction in which the second fixed contact21and the second movable contact32face each other; an upward/downward direction inFIG. 1) and an upward direction defines a direction from the first movable contact31toward the first fixed contact11. Further, a rightward/leftward direction defines a direction in which the first fixed terminal1and the second fixed terminal2are aligned side by side (a rightward/leftward direction inFIG. 1) and a rightward direction defines a direction from the first fixed terminal1toward the second fixed terminal2. That is to say, in the following description, the upward, downward, rightward, and leftward directions are supposed to be defined on the basis of the directions shown inFIG. 1. Furthermore, in the following description, a direction perpendicular to both the upward/downward direction and the rightward/leftward direction (i.e., the direction coming out of the paper on whichFIG. 1is depicted) is defined herein to be a forward/backward direction. However, these directions are not intended to limit the usage of the circuit interrupter100.

The first fixed terminal1and the second fixed terminal2are placed to be arranged side by side in the rightward/leftward direction (seeFIG. 1). Each of the first fixed terminal1and the second fixed terminal2is made of a metallic material with electrical conductivity. The first fixed terminal1and the second fixed terminal2function as terminals for connecting the external electric circuitry (the circuitry constituting the power supply system200) to the first fixed contact11and the second fixed contact21. In the present embodiment, each of the first fixed terminal1and the second fixed terminal2is made of copper (Cu) as an example. However, not limited thereto, each of the first fixed terminal1and the second fixed terminal2may be made of an electrically conductive material other than copper.

As shown inFIG. 2, the first fixed terminal1includes a connection piece110, an electrode piece120, an interconnection piece130, and a circuit piece140which are formed as an integral part.

The connection piece110has a rectangular plate shape with a thickness in the upward/downward direction and a length in the forward/backward direction. In the present embodiment, a lower surface of the connection piece110functions as the first fixed contact11but is not limited thereto. The first fixed contact11, for example, may be made of a separate member from the connection piece110and fixed to the connection piece110by welding or the like.

The electrode piece120has a plate shape with a thickness in the forward/backward direction. The electrode piece120has a square shape and includes a through hole in its center. The electrode piece120is configured to be connected to the first end of the external electric circuitry. That is, the electrode piece120functions as the first electrode12to be connected to the first end of the external electric circuitry.

The interconnection piece130has a rectangular plate shape with a thickness in the rightward/leftward direction and a length in the upward/downward direction. A lower side of the interconnection piece130is connected to a left side of the connection piece110.

The circuit piece140has a plate shape with a thickness in the forward/backward direction. The circuit piece140interconnects the electrode piece120and the interconnection piece130. A left side of the circuit piece140is coupled to an upper portion of a right side of the electrode piece120. The right side of the circuit piece140is coupled to a center of a left surface of the interconnection piece130.

As shown inFIG. 2, the second fixed terminal2includes a connection piece210, an electrode piece220, an interconnection piece230, and a circuit piece240which are formed as an integral part.

The connection piece210has a rectangular plate shape with a thickness in the upward/downward direction and a length in the forward/backward direction. In the present embodiment, a lower surface of the connection piece210functions as the second fixed contact21but is not limited thereto. The second fixed contact21, for example, may be made of a separate member from the connection piece210and fixed to the connection piece210by welding or the like.

The electrode piece220has a plate shape with a thickness in the forward/backward direction. The electrode piece220has a square shape and includes a through hole in its center. The electrode piece220is configured to be connected to the second end of the external electric circuitry. That is, the electrode piece220functions as the second electrode22to be connected to the second end of the external electric circuitry.

The interconnection piece230has a rectangular plate shape with a thickness in the rightward/leftward direction and a length in the upward/downward direction. A lower side of the interconnection piece230is coupled to a right side of the connection piece210.

The circuit piece240has a plate shape with a thickness in the forward/backward direction. The circuit piece240interconnects the electrode piece220and the interconnection piece230. The right side of the circuit piece240is coupled to an upper portion of the left side of the electrode piece220. The left side of the circuit piece240is coupled to a center of a right surface of the interconnection piece230.

As shown inFIG. 1, the first fixed terminal1is fixed to the housing7so that the electrode piece120protrudes outside from a left wall of the housing7and a lower end of the interconnection piece130and the connection piece110are placed in an inside space of the housing7(the accommodation70). The second fixed terminal2is fixed to the housing7so that the electrode piece220protrudes outside from a right wall of the housing7and a lower end of the interconnection piece230and the connection piece210are placed in the inside space of the housing7(the accommodation70).

As shown inFIGS. 1-3, the movable contactor3has a plate shape which has a thickness in the upward/downward direction and is lager in the rightward/leftward direction than in the forward/backward direction. The movable contactor3is placed below the connection piece110and the connection piece210to allow its opposite ends in a length direction (the rightward/leftward direction to face (be connected to) the first fixed contact11and the second fixed contact21. The first movable contact31is provided to a part of the movable contactor3which faces the first fixed contact11and the second movable contact32is provided to a part of the movable contactor3which faces the second fixed contact21(seeFIG. 1).

In the present embodiment, the first movable contact31is in contact with the first fixed contact11. More particularly, the first movable contact31is in surface contact with the first fixed contact11. The second movable contact32is in contact with the second fixed contact21. More particularly, the second movable contact32is in surface contact with the second fixed contact21.

In the present embodiment, the first movable contact31is a separate member from the movable contactor3, is made of silver (Ag), and is fixed to the movable contactor3by welding or the like. Similarly, the second movable contact32is a separate member from the movable contactor3, is made of silver (Ag) and is fixed to the movable contactor3by welding or the like. However, not limited thereto, each of the first movable contact31and the second movable contact32may be formed integrally with the movable contactor3by striking the movable contactor3partially.

As shown inFIG. 1, the movable contactor3is accommodated in the inside space of the housing7(the accommodation70). The movable contactor3is held by the holding unit4so that the first movable contact31and the second movable contact32are connected to the first fixed contact11and the second fixed contact21, respectively.

The first fixed terminal1and the second fixed terminal2are short-circuited through the movable contactor3. That is, the first electrode12of the first fixed terminal1is electrically connected to the second electrode22of the second fixed terminal2through the first fixed contact11, the first movable contact31, the movable contactor3, the second movable contact32and the second fixed contact21(seeFIG. 2). Therefore, when the first electrode12and the second electrode22are electrically connected to the first end and the second end of the electric circuitry respectively, the circuit interrupter100forms an electric path between the first electrode12and the second electrode22.

As shown inFIGS. 1, 3, the housing7includes an inner hollow cylinder71, an outer hollow cylinder72, and a cover member73.

The inner hollow cylinder71is made of a material having electrically insulating properties, for example, a resin material. The inner hollow cylinder71has a bottomed hollow circular cylindrical shape with a closed lower surface and an open upper surface. A holding rib711which has a hollow circular cylindrical shape is provided to an upper surface of a lower wall of the inner hollow cylinder71(a bottom surface of the inner hollow cylinder71). The holding rib711is formed concentrically with the inner hollow cylinder71.

The outer hollow cylinder72is made of, for example, a metal material. The outer hollow cylinder72is preferably made of a non-magnetic metal material. Examples of the non-magnetic metallic material may include an austenitic stainless steel such as SUS304. However, the material of the outer hollow cylinder72may not be non-magnetic and may be, for example, an alloy containing iron as a main component, such as 42 alloy.

The outer hollow cylinder72is concentric with the inner hollow cylinder71and has a bottomed hollow circular cylindrical shape with a closed lower surface and an open upper surface. The outer hollow cylinder72is provided to surround a periphery of the inner hollow cylinder71. In other words, the outer hollow cylinder72is a strength member for improving the strength of the housing7(the strength of an outer wall of the accommodation70).

The inner hollow cylinder71may be integrally formed with the outer hollow cylinder72by, for example, insert molding or the like. The housing7may not include the outer hollow cylinder72.

The cover member73is made of a material having electrically insulating properties, for example, a resin material. The cover member73has a bottomed hollow cylindrical shape with a closed upper surface and a lower surface having an opening. The cover member73, for example, may be formed integrally with the first fixed terminal1and the second fixed terminal2by insert molding.

A thickness of an upper wall of the cover member73is larger than a thickness of a side wall of the cover member73. A through hole731which is concentric with the cover member73is formed in a center of the upper wall of the cover member73. The pyroactuator5is placed inside the through hole731of the cover member73. A lower end of the pyroactuator5protrudes from a lower surface (inner surface) of the upper wall of the cover member73. The through hole731is hermetically closed by the pyroactuator5(a case52thereof).

An annular recessed groove732is formed in a lower surface of the side wall of the cover member73. By inserting upper edges of the inner hollow cylinder71and the outer hollow cylinder72into the recessed groove732, the inner hollow cylinder71and the outer hollow cylinder72are coupled to the cover member73. As a result, the housing7has the airtight inside space (the accommodation70) surrounded by the inner hollow cylinder71and the cover member73. The first fixed contact11, the second fixed contact21, and the movable contactor3are accommodated in the inside space (the accommodation70) of the housing7.

In the present embodiment, the shape of the housing7is a substantially circular cylindrical shape having an inside space (the accommodation70) but may not be limited thereto. It is sufficient that the housing7has any shape as long as it has an inside space (the accommodation70) for accommodating the first fixed contact11, the second fixed contact21, and the movable contactor3. The housing7may have another shape such as a hollow polygonal prism (for example, a hollow rectangular parallelepiped shape).

The first yoke61is a ferromagnetic body and may be made of a metallic material such as iron. The first yoke61is fixed to the lower surface of the movable contactor3and is integral with the movable contactor3(seeFIGS. 1, 3). That is, the first yoke61is fixed to an opposite surface of the movable contactor3from a surface where the first movable contact31and the second movable contact32are placed.

When a current flows through the movable contactor3, the first yoke61allows a magnetic field caused by the current to pass through the first yoke61. That is, when the first yoke61is not provided, the (concentric) magnetic field around the current flowing through the movable contactor3is generated. When the first yoke61is provided, the magnetic field is changed so as to pass through the first yoke61. Therefore, the center of the magnetic field acting on the current flowing through the movable contactor3is attracted toward the surface where the first movable contact31and the second movable contact32are placed (i.e., the upper surface). As a result, a relatively upward force is generated in the movable contactor3. Therefore, the connection between the pair of the first movable contact31and the second movable contact32and the pair of the first fixed contact11and the second fixed contact21are more easily maintained in a case where the first yoke61is provided than in a case where the first yoke61is not provided.

An engagement recess610which is a circular cylindrical recess is formed in a lower surface of the first yoke61.

The second yoke62is a ferromagnetic body and may be made of a metallic material such as iron. The second yoke62is positioned and fixed at a position facing the first yoke61with the movable contactor3in-between and is separated from the movable contactor3. The second yoke62may be in contact with the second end532(lower end) of the piston53of the pyroactuator5. In this embodiment, the second yoke62is fixed to the second end532(lower end) of the piston53of the pyroactuator5. The second yoke62is placed to face the center of the movable contactor3(seeFIG. 2) but not to be in contact with the movable contactor3by a gap (seeFIG. 3). The second yoke62is electrically insulated from the movable contactor3.

The second yoke62includes a pair of protrusion parts621,622(seeFIG. 3) protruding in the upward direction at its both ends in the forward/backward direction. In other words, formed on both ends in the forward/backward direction of the upper surface of the second yoke62are the protrusion parts621,622respectively facing the side surface in the forward/backward direction of the movable contactor3. As shown inFIG. 3, a distal end surface (lower end surface) of the protrusion part621which is a front one of the pair of protrusion parts621,622faces a front end of the first yoke61and a distal end surface (lower end surface) of the protrusion part622which is a back one of the pair faces a back end of the first yoke61. Therefore, when a current flows between the first fixed terminal1and the second fixed terminal2through the movable contactor3, a magnetic flux passing through a magnetic path formed by the first yoke61and the second yoke62is developed. At this time, the front end of the first yoke61and the protrusion part621at the front end of the second yoke62are magnetized to have different polarities. The back end of the first yoke61and the protrusion part622at the back end of the second yoke62are magnetized to have different polarities. As a result, an attraction force acts between the first yoke61and the second yoke62. The second yoke62is fixed to the second end532(lower end) of the piston53and therefore the attraction force moves the first yoke61in the upward direction. When the first yoke61is move in the upward direction, an upward force is applied to the movable contactor3by the first yoke61.

While a current flows through the movable contactor3, this current may cause an electromagnetic repulsive force separating the first movable contact31and the second movable contact32from the first fixed contact11and the second fixed contact21. That is, when a current flows through the movable contactor3, the Lorentz force may cause the electromagnetic repulsive force, which moves the movable contactor3downward, on the movable contactor3.

In the present embodiment, as described above, the magnetic field is changed by the first yoke61to pass through the first yoke61and therefore an upward force is generated in contrast to a case where the first yoke61is not provided. The above-mentioned attraction force acts between the first yoke61and the second yoke62. Consequently, the current flowing through the movable contactor3causes a force moving the movable contactor3upward, i.e. a force pressing the first movable contact31and the second movable contact32onto the first fixed contact11and the second fixed contact21, respectively.

As described above, the first yoke61and the second yoke62serves as a connection maintenance mechanism which produces a force maintaining the connection between the pair of the first movable contact31and the second movable contact32and the pair of the first fixed contact11and the second fixed contact21by using a current flowing through the movable contactor3.

Placed between the protrusion parts621,622of the second yoke62and the both ends in the forward/backward direction of the upper surface of the first yoke61are spacers631,632made of a material having electrically insulating properties, for example, a resin material (seeFIG. 3). Thus, the electrically insulating properties between the second yoke62and the first yoke61are ensured.

As shown inFIGS. 1, 3, the holding unit4of the present embodiment includes a contact pressure spring41. The contact pressure spring41is a coil spring. The contact pressure spring41is placed between the bottom surface (inner surface) of the inner hollow cylinder71and the lower surface of the first yoke61. The contact pressure spring41has a coil axis extending along the upward/downward direction. The holding rib711of the inner hollow cylinder71is inserted into an inside of a first end411of the contact pressure spring41. A second end412of the contact pressure spring41is inserted into the engagement recess610of the first yoke61. The contact pressure spring41gives an upward elastic force to the movable contactor3via the first yoke61. That is, the circuit interrupter100includes as the holding unit4an elastic part (the contact pressure spring41) for providing to the movable contactor3an elastic force in a direction in which the movable contact (first movable contact)31is connected to the fixed contact (first fixed contact)11(in a direction toward the closed position).

The contact pressure spring41presses the movable contactor3in the upward direction through the first yoke61. The contact pressure spring41holds the movable contactor3so that the first movable contact31is connected to the first fixed contact11and the second movable contact32is connected to the second fixed contact21.

FIG. 4shows a cross-sectional view of the pyroactuator5of the present embodiment. The pyroactuator5of the present embodiment has a so-called pin pusher structure configured to push out the piston53(the pin535) by use of gas generated in the squib51.

As shown inFIG. 4, the pyroactuator5includes the squib51, a case52having the pressurized chamber520therein, and the piston53.

The squib51includes a body511, a metal sleeve (metal CAN)512, a combustion part513, a pair of pin electrodes514, and a heating element515.

The body511is made of, for example, a resin material or the like having electrically insulating properties and has a bottomed hollow circular cylindrical shape with an open upper surface and a closed lower surface. The inside space S110of the body511is sealed with a sealing material having electrically insulating properties such as glass.

The metal sleeve512is made of metal such as stainless steel, for example, and includes a hollow circular cylindrical part having a bottomed hollow circular cylinder with an open upper surface and a closed lower surface and a flange part protruding laterally from an upper end of the hollow circular cylindrical part, which are formed integrally. Formed in a center of a lower wall of the metal sleeve512(the hollow circular cylindrical part thereof) is a cross groove with a depth not penetrating through the lower wall or the like. That is, a portion of the lower wall of the metal sleeve512serves as a lower strength portion which is lower in strength (more easily broken) than the other portion of the metal sleeve512. The metal sleeve512is coupled to the body511at the flange with bond to cover the lower surface of the body511.

The combustion part513includes an explosive such as nitrocellulose, for example. The combustion part513is placed in a space surrounded by the body511and the metal sleeve512. The explosive contained in the combustion part513may be any material that generates an electrically insulating gas by combustion and is not limited to nitrocellulose.

Each of the pair of pin electrodes514has a first end positioned within the combustion part513(in the space surrounded by the body511and the metal sleeve512) and a second end exposed outside the pyroactuator5through the body511. The second ends of the pair of pin electrodes514are connected to the control circuitry207.

The heating element515is an element that generates heat by energization. In the present embodiment, the heating element515is a nichrome wire. The heating element515is placed in the combustion part513(the space surrounded by the body511and the metal sleeve512). The heating element515is connected between the first ends of the pair of pin electrodes514.

In the squib51, when a current from the control circuitry207flows between the pair of pin electrodes514, the heating element515generates heat and this causes increase in the temperature of the combustion part513. When the temperature of the combustion part513(a surrounding part of the heating element515) exceeds an ignition temperature, the explosive combusts explosively to generate a large amount of gas (for example, carbon monoxide gas, carbon dioxide gas, nitrogen gas) instantaneously. When the pressure in the combustion part513exceeds a withstand pressure of the low strength portion of the metal sleeve512due to generation of gas, the low strength portion is broken and the gas generated by combustion is discharged to the outside (in this embodiment, the lower pressurized chamber520) through the broken portion.

As shown inFIG. 4, the piston53includes a base533, a cylinder534, the pin (rod)535, and a spring536.

The base533is formed of an electrically insulating material such as, for example, resin, and is made of, for example, polycarbonate or polybutylene terephthalate. The base533includes a first columnar section, a second columnar section, and a third columnar section in this order from the top each of which has a circular cylindrical shape. The first columnar section, the second columnar section, and the third columnar section are connected (concentrically) in the upward/downward direction with their axes being aligned. An outer diameter of the first columnar section is larger than an outer diameter of the second columnar section and the outer diameter of the second columnar section is larger than an outer diameter of the third columnar section. An annular holding groove5330which is concentric with the first columnar section and the second columnar section is formed at a boundary between the first columnar section and the second columnar section on an outer side surface of the base533.

In the present embodiment, a bottom surface (upper surface) of the first columnar section of the base533serves as the first end531of the piston53.

The cylinder534is made of an electrically insulating material such as resin. The cylinder534is formed in a hollow circular cylindrical shape. An inner diameter of the cylinder534is approximately equal to the outer diameter of the third columnar section of the base533but is smaller than the outer diameter of the second columnar section of the base533. The outer diameter of the cylinder534is smaller than the outer diameter of the second columnar section of the base533. The third columnar section of the base533is fitted into an opening in the upper surface of the cylinder534and thus the cylinder534and the base533are coupled to each other.

The pin535is made of an electrically insulating material such as, for example, resin, and is made of, for example, polycarbonate or polybutylene terephthalate. The pin535includes a large diameter portion and a small diameter portion in this order from the top each of which has a circular cylindrical shape. The large diameter portion and the small diameter portion are (concentrically) connected in the upward/downward direction with their axes being aligned. A length in an axial direction (the upward/downward direction) of the large diameter portion of the pin535is comparable to the length of the cylinder534. Specifically, the length of the pin535is slightly greater than the distance between the bottom surface (lower surface) of the base533coupled to the cylinder534and the lower end of the cylinder534. As shown inFIG. 1, the small diameter portion of the pin535is fixed in the through hole of the second yoke62. In the present embodiment, part including the small diameter portion of the pin535serves as the second end532of the piston53.

As shown inFIG. 4, the spring536is a coil spring. The spring536defines a relative position between the cylinder534and the pin535. Specifically, the spring536is sandwiched between an inner side surface of the cylinder534and an outer side surface of the pin535to hold the pin535inside the cylinder534.

The case52includes a holder521, a sleeve522, a cap523, a first holding spring524, and a second holding spring525. The case52is formed in a substantially hollow circular cylindrical shape as a whole.

The holder521of the case52is made of metal, for example, aluminum or an aluminum alloy. The holder521has a substantially hollow circular cylindrical shape with open upper and lower surfaces and has an inner side surface which is a circumferential surface with multiple steps. The holder521holds the squib51and the piston53.

The squib51is fitted into a space at an upper part of the holder521of the case52. An inner surface of the upper part of the holder521has a shape in substantially close contact with the outer surface of the squib51(the outer side surface of the body511, the outer surface of the flange part of the metal sleeve512, the outer side surface of the hollow circular cylindrical part of the metal sleeve512). The opening on the upper side of the holder521(the inner space thereof) is closed by the squib51.

The base533of the piston53is fitted into a space of a lower part of the holder521of the case52. An inner surface of the lower part of the holder521has a shape in substantially close contact with the outer side surface of the first columnar section of the base533. An opening on a lower side of the holder521(the inner space thereof) is closed by the piston53(the base533thereof).

By attaching the squib51and the piston53to the case52, a closed airtight space is formed between the lower surface of the squib51(the metal sleeve512thereof), the upper surface of the piston53(the base533thereof) and the inner surface of the case52(the holder521thereof). The gas generated by the squib51is introduced into the airtight space through the broken portion of the lower wall of the metal sleeve512. That is, the airtight space functions as the pressurized chamber520that receives the pressure of the gas generated by the squib51.

The sleeve522of the case52is made of metal, for example, steel. The sleeve522is placed below the holder521to make its outer side surface continuous to an outer side surface of the holder521. The sleeve522is formed in a substantially cylindrical shape having open upper and lower surfaces. The sleeve522includes a first cylindrical portion, a second cylindrical portion and a third cylindrical portion which have a hollow circular cylindrical shape and are arranged in this order from above. The first cylindrical portion, the second cylindrical portion and the third cylindrical portion are connected in the upward/downward direction with these axes aligned (concentrically). The inner surface of the first cylindrical portion is formed in a tapered shape with a smaller diameter toward the lower side. The inner side surface of the second cylindrical portion is formed in a hollow circular cylindrical shape having a constant diameter. The inner diameter of the second cylindrical portion is substantially equal to the outer diameter of the first columnar section (the largest diameter portion) of the base533of the piston53. The inner side surface of the third cylindrical portion is formed in a tapered shape with a smaller diameter toward the lower side. The diameter of the inner side surface of the third cylindrical portion is substantially equal to the outer diameter of the first columnar section of the base533(the largest diameter portion in the base533) at its upper end and becomes smaller toward the lower end. In other words, the third cylindrical portion of the sleeve522has a shape not allowing the base533of the piston53to pass therethrough.

There are two channels50interconnecting the inside and the outside of the case52formed in the side wall of the sleeve522of the case52. As shown inFIG. 1, each channel50includes a first end501connected to the accommodation70and a second end502connected to the inside space of the case52. Each channel50has a circular cylindrical shape having a constant diameter. One of the two channels50(a left channel50inFIG. 1) is formed in part of the side wall of the sleeve522of the case52which faces the first fixed terminal1. The channel50guides the gas generated by the squib51to allow the gas to blow into the predetermined space S1between the first movable contact31and the first fixed contact11(a space including a track of movement of the first movable contact31, seeFIG. 7). That is, the gas generated by the squib51is introduced into the predetermined space S1between the fixed contact (first fixed contact)11and the movable contact (first movable contact)31while the movable contactor3is in the open position. The other of the two channels50(a right channel50inFIG. 1) is formed in part of the side wall of the sleeve522of the case52which faces the second fixed terminal2.

The channel50guides the gas generated by the squib51to allow the gas to blow into the predetermined space S2between the second movable contact32and the second fixed contact21(a space including a track of movement of the second movable contact32). Each of the two channels50extends obliquely downward from the inside to the outside of the case52.

In the present embodiment, each channel50is linear. However, the shape of the channel50is not particularly limited, and may be another shape such as a curved shape, for example. The diameter of the channel50is not particularly limited. The direction in which the channel50extends is not particularly limited, and may extend laterally (in a horizontal direction), for example. Further, there is no particular limitation on the position where the channel50is formed, and the channel50may be formed, for example, in a front portion or a back portion of the side wall of the sleeve522of the case52. However, it is preferable that each of the channels50is formed in a shape, a diameter, an orientation, and a position to allow the gas generated by the squib51to blow into the predetermined space S1or the predetermined space S2.

The cap523of the case52is made of metal, for example, steel. The cap523is placed below the sleeve522to make its outer side surface continuous to the outer side surface of the sleeve522. The cap523has a hollow circular cylindrical shape with both upper and lower surfaces open. A projecting portion (flange) projecting inward is formed at the lower surface of the cap523. An inner diameter of the projecting portion (flange) is approximately equal to the outer diameter of the cylinder534of the piston53. The piston53is an operating pin which moves in one direction in response to reception of the pressure of the gas generated by the squib51.

In the present embodiment, the outer diameters of the holder521, the sleeve522, and the cap523are equal to each other.

The first holding spring524includes a clamping portion having a hollow disk shape and a holding portion having a hollow frustoconical shape protruding obliquely upward from an inner side surface of the clamping portion. The clamping portion of the first holding spring524is sandwiched between the holder521and the sleeve522of the case52. Thereby, the first holding spring524is sandwiched between the holder521and the sleeve522. The first holding spring524seals a gap at a boundary between the holder521and the sleeve522. The holding portion is in contact with the holding groove5330of the base533of the piston53and applies an upward force to the base533to hold the base533(prevent downward movement of the base533).

The second holding spring525includes a clamping portion having a hollow disk shape and a holding portion having a hollow frustoconical shape protruding obliquely downward from an inner side surface of the clamping portion. The clamping portion of the second holding spring525is sandwiched between the sleeve522and the cap523of the case52. Thereby, the second holding spring524is sandwiched between the sleeve522and the cap523. The second holding spring525seals a gap at a boundary between the sleeve522and the cap523. A protruding tip of the holding portion is away from the outer side surface of the cylinder534of the piston53. A diameter of the protruding tip of the holding portion is approximately equal to the outer diameter of the second columnar section of the base533of the piston53.

As shown inFIG. 4, in a state where the squib51and the piston53is attached to the case52, the pin electrode514of the squib51protrudes from the upper surface of the case52. Further, the small diameter portion of the pin535protrudes downward from the lower surface of the case52.

As shown inFIG. 1, the pyroactuator5is attached to the housing7so that the case52closes the through hole731of the cover member73. In this state, the second end of the piston53(the lower end of the pin535) faces the center of the movable contactor3(the center in the length direction and the width direction).

Next, the operation of the circuit interrupter100having the above-described configuration will be described with reference toFIGS. 1, 6, 7.

As to the circuit interrupter100, the first electrode12is connected to the first end of the electric circuitry (e.g., the circuitry constituting the power supply system200) and the second electrode22is connected to the second end of the electric circuitry. Here, the first end of the electric circuitry is given a higher potential than the second end.

In a normal state of the electric circuitry, the movable contactor3is held by the spring force of the pressure spring41and the like so that the first movable contact31is connected to the first fixed contact11and the second movable contact32is connected to the second fixed contact21(seeFIG. 1). In summary, in the normal state of the electric circuitry, the movable contactor3is in the closed position where the first movable contact31is in contact with the first fixed contact11and the second movable contact32is in contact with the second fixed contact21. At this time, a current flows from the first electrode12to the second electrode22by passing through the first fixed contact11, the first movable contact31, the movable contactor3, the second movable contact32, and the second fixed contact21in this order.

At this time, the contact between the first movable contact31and the first fixed contact11and the contact between the second movable contact32and the second fixed contact21are maintained by the spring force of the contact pressure spring41, the attraction force between the first yoke61and the second yoke62, and the like. Incidentally, even if an overcurrent or the like flows in the circuit interrupter100, contact between the contacts is maintained due to the attraction force between the first yoke61and the second yoke62and the like as long as the magnitude of the overcurrent is relatively small.

When the current flowing through becomes an abnormal current with its value equal to or higher than a prescribed value (in an abnormal state of the electric circuitry), the control circuitry207detects the abnormal current. Upon detecting the abnormal current, the control circuitry207operates (activates) the circuit interrupter100to break the electric circuitry.

Specifically, the control circuitry207allows a current to flow between the pair of pin electrodes514to energize the heating element515. When energized, the heating element515generates heat and increases the temperature of the combustion part513. When the temperature of the combustion part513exceeds the ignition temperature of the explosive, the explosive is combusted to generate a large amount of gas and the low strength portion of the lower wall of the metal sleeve512is broken by the pressure of the gas and the gas is discharged to the pressurized chamber520through the broken portion. Since the combustion part513explosively combusts to generate a large amount of gas, the pressure in the pressurized chamber520rapidly increases in a short time.

In an initial state, the piston53is in the first position (seeFIG. 1). The piston53receives the pressure in the pressurized chamber520with the first end531(the upper surface of the base533) and then is pressed downward to press the movable contactor3downward with the second end532(the pin535). The piston53applies a force to part of the movable contactor3between the first movable contact31and the second movable contact32to move the movable contactor3downward. The piston53moves to the second position (seeFIG. 7) while pressing the movable contactor3.

Specifically, in the piston53, the bottom surface (upper surface) of the base533receives the pressure in the pressurized chamber520and the base533starts to move downward together with the cylinder534against the spring force of the first holding spring524. An initial speed of the base533(the piston53) at this time becomes very large because of the large pressure in the pressurized chamber520. The pin535receives a downward force from the cylinder534via the spring536and starts to move downward slightly later from the start of downward movement of the cylinder534. The pin535, the second yoke62, the first yoke61and the movable contactor3is provided as an integral part. Due to downward movement of the pin535, the movable contactor3is pressed downward and then moves downward. Here, after start of downward movement of the base533, an elastic force stored in the spring536acts on the pin535and therefore a very large downward force is applied on the pin535and thus the initial speed also increases.

A force pressing the movable contactor3downward exceeds a force supporting the movable contactor3upward (the spring force of the contact pressure spring41, the attraction force between the first yoke61and the second yoke62, and the like), the movable contactor3moves downward while compressing the contact pressure spring41through the first yoke61. Thus, the first movable contact31is separated from the first fixed contact11and the second movable contact32is separated from the second fixed contact21(seeFIG. 6). As a result, the electric path between the first fixed terminal1and the second fixed terminal2is interrupted and the current flowing through the electric path between the first fixed terminal1and the second fixed terminal2is interrupted.

The piston53, the first yoke61, the movable contactor3, and the second yoke62is integrally moved downward (hereinafter, for convenience of explanation, a set of the piston53, the first yoke61, the movable contactor3, and the second yoke62is referred to as a movable body). A direction in which the piston53moves and a direction in which the movable contactor3moves by the piston53are the same direction. Typically, the movable body moves to a position where the contact pressure spring41is most compressed (the second position) (seeFIG. 7). In summary, the movable contactor3moves to the open position where the first movable contact31is separated from the first fixed contact11and the second movable contact32is separated from the second fixed contact21. At this time, the base533of the piston53moves inside the third cylindrical portion while pressing and expanding (modifying) the inner surface of the third cylindrical portion of the sleeve522of the case52. Incidentally, kinetic energy of the movable body is converted into elastic energy of the contact pressure spring41, thermal energy generated when the movable body strikes the bottom surface of the inner hollow cylinder71, and the like.

The movable body receives an upward force from the compressed contact pressure spring41at a position where the contact pressure spring41is compressed. However, the upward movement of the movable body is blocked by a frictional force between the base533and the third cylindrical portion of the sleeve522of the case52. As a result, the movable body stops at a position shown inFIG. 7(the second position). In other words, the third cylindrical portion functions as a detent mechanism that mechanically holds the piston53after movement of the movable contactor3to prevent the piston53from returning to its original position (the first position).

Further, the downward movement of the piston53(movement from the first position to the second position) extends the space in the case52the pressure of which is increased by introduction of the gas of the squib51(the pressurized chamber520). As shown inFIG. 7, extension of the pressurized chamber520allows the second end502of each channel50to be connected to the pressurized chamber520. As a result, the pressurized chamber520and the accommodation70are interconnected by the channel50. Therefore, the gas generated by the squib51is introduced into the accommodation70through the pressurized chamber520and the channel50. In the present embodiment, the gas introduced into the accommodation70goes to the predetermined space S1between the first movable contact31and the first fixed contact11or the predetermined space S2between the second movable contact32and the second fixed contact21(see arrow W1inFIG. 7).

Here, when the first movable contact31is pulled away from the first fixed contact11while a current flows in the movable contactor3, there is a possibility that an arc is generated between the first movable contact31and the first fixed contact11(see dotted line A1inFIG. 8A). Similarly, when the second movable contact32is pulled away from the second fixed contact21while a current flows in the movable contactor3, there is a possibility that an arc is generated between the second movable contact32and the second fixed contact21.

In contrast, in the circuit interrupter100of the present embodiment, the gas generated by the squib51of the pyroactuator5(electrically insulating gas) is introduced into the accommodation70, thereby increasing the pressure of the accommodation70. The accommodation70forms a sealed space together with the pressurized chamber520. The accommodation70accommodates the fixed contact (first fixed contact)11and the movable contact (first movable contact)31therein, and includes the predetermined space S1. The accommodation70is also a space where an arc occurs therein. Increase in the pressure of the accommodation70causes the arc generated between the contacts to be cooled. Therefore, the electrically insulating properties of the plasma of the arc discharge or the metal vapor is enhanced and the extinction of the arc is promoted.

Further, in the circuit interrupter100of the present embodiment, the gas introduced from the channel50into the accommodation70blows into the predetermined space S1between the first movable contact31and the first fixed contact11, or the predetermined space S2between the second movable contact32and the second fixed contact21. Thus, the arc generated between the contacts is cooled and the arc extinction is promoted.

More specifically, as to a process of movement of the movable contactor3from the closed position to the open position, in the early stage of movement from the closed position to the open position, a positive column of the arc discharge is developed between the fixed contact (first fixed contact)11and the movable contactor3(see dotted line A1inFIG. 8A). As the position is changed from the closed position to the open position, the gas is introduced into the accommodation70. The gas strikes the positive column and then the positive column is deformed by the pressure of the gas, thereby stretching the arc (see dotted line A2inFIG. 8B). Furthermore, the arc is stretched by the gas. In some cases the arc is pressed against the wall surface of the inner hollow cylinder71(see dotted line A3inFIG. 8C). Thus, the arc is stretched by the gas and then the arc is interrupted. That is, the gas generated by the squib51is introduced into a gap between the fixed contact (first fixed contact)11and the movable contactor3. Thereby, the arc extinction is promoted and the interruption performance can be improved. Incidentally, the arc generated between the second movable contact32and the second fixed contact21is blown by the gas and then stretched. Thus, the arc extinction is promoted.

Thus, in the circuit interrupter100of the present embodiment, the gas generated by the squib51is introduced into the predetermined spaces S1, S2. Thereby, it is possible to quickly extinguish the arc.

The inner wall (inner hollow cylinder71) of the housing7may be made of a resin material (arc extinction gas generating member) which releases an arc extinction gas by being heated by a stretched arc. Examples of the arc extinction gas may include CO2gas, N2gas, and H2O gas. The arc extinction gas makes it possible to quickly extinguish the arc.

The circuit interrupter100of one variation of embodiment 1 will be described with reference toFIGS. 9,10. Hereinafter, the circuit interrupter100of embodiment 1 described above is also referred to as the circuit interrupter100of the basic example of embodiment 1.

FIGS. 9, 10show cross-sectional views of the circuit interrupter100of one variation before and after operation. Only for convenience, the first yoke61and the second yoke62are not depicted inFIGS. 9, 10. InFIGS. 9, 10, the illustration of the case52is simplified. However, similarly to the circuit interrupter100of embodiment 1, the case52may include, as the detent mechanism, the second cylindrical portion (a portion having a frustoconical inner surface whose diameter decreases toward the lower side) and the third cylindrical portion (a portion having a cylindrical inner surface having a smaller diameter than the base533of the piston53). Further, in the circuit interrupter100of one variation, the piston53is one molded article. Further, in the circuit interrupter100of one variation, although the shapes of the first fixed terminal1and the second fixed terminal2are different from those of the circuit interrupter100of the basic example of embodiment 1 but may be the same.

In the circuit interrupter100of one variation, the channel50has a tapered cylindrical shape which is gradually smaller in diameter toward the outside (the accommodation70) of the case52than at the inside of the case52. That is, a diameter of the first end501of the channel50(an end close to the accommodation70) is smaller than a diameter of the second end502. Thus, a flow rate of the gas flowing from the second end502to the first end501is increased in the channel50. Thus, the flow rate of the gas in the predetermined space S1, S2is increased. Therefore, it is possible to cool the arc generated between the contacts more effectively and to further promote the arc extinction.

Further, in the circuit interrupter100of one variation, the predetermined space S1between the first fixed contact11and the first movable contact31while the movable contactor3is in the open position is located on an extension line of one channel50(the left one inFIGS. 9, 10). In other words, the extension line of one channel50intersects a line segment interconnecting the first movable contact31of the movable contactor3after movement and the first fixed contact11(referred to as a “first line segment”). In particular, the extension of one channel50intersects the first line segment in the vicinity of the first fixed contact11. Further, the predetermined space S2between the second fixed contact21and the second movable contact32while the movable contactor3is in the open position is located on an extension line of the other channel50(the right one inFIGS. 9, 10). In other words, the extension line of the other channel50intersects a line segment interconnecting the second movable contact32of the movable contactor3after movement and the second fixed contact21(referred to as a “second line segment”). In particular, the extension of the other channel50intersects the second line segment in the vicinity of the second fixed contact21. With this configuration, in the circuit interrupter100of one variation, gases introduced into the accommodation70from the individual channels50goes to the predetermined spaces S1, S2which are spaces between the contacts, and thus blow the arcs generated between the contacts directly (see arrow W2inFIG. 10). Therefore, it is possible to cool the arc more effectively and to further promote the arc extinction. In addition, the arc can be extended more effectively and further the arc extinction can be promoted.

In the circuit interrupter100of the basic example and one variation of embodiment 1, the channel50is not limited to a columnar (cylindrical) shape formed in the side wall of the case52. The channel50may be, for example, a cutout extending upward from the lower end of the side wall of the case52.

In the circuit interrupter100of the basic example and one variation of embodiment 1, the pyroactuator5is not limited to being configured to move the movable contactor3by use of the piston53. For example, the circuit interrupter100of embodiment 1 may be configured to allow the movable contactor3to receive the pressure of the gas generated in the squib51directly (the movable contactor3forms part of the outer wall of the pressurized chamber520) and to allow the movable contactor3to be moved directly by the pressure of the gas. In this case, the channel50may not be provided in the case52.

The circuit interrupter100of embodiment 2 will be described with reference toFIGS. 11, 12.

The circuit interrupter100of embodiment 2 is mainly different from embodiment 1 in that the moving mechanism for moving the movable contactor3from the closed position to the open position includes a trip device8. Configurations common to the circuit interrupter100of embodiment 2 and embodiment 1 are denoted by the same reference signs and explanations thereof are omitted appropriately.

Similarly to embodiment 1, the circuit interrupter100of the present embodiment includes the first fixed terminal1, the second fixed terminal2, the movable contactor3, the holding unit4(the contact pressure spring42serving as an elastic part), the squib51, the case52, and the housing7. However, in the circuit interrupter100of the present embodiment, the moving mechanism includes the trip device8instead of the pressurized chamber520and the piston53. The trip device8moves the movable contactor3from the closed position to the open position in accordance with the abnormal current flowing in the circuit including the movable contact (first movable contact)31and the fixed contact (first fixed contact)11.

As shown inFIG. 11, the trip device8of the present embodiment includes, an excitation coil81, a mover82, a stator83, and a hollow cylindrical body84. The trip device8of the present embodiment moves the movable contactor3to the open position by use of an electromagnetic force generated by a magnetic flux generated in the excitation coil81when the abnormal current flows through the excitation coil81.

The excitation coil81includes a first end connected to the first fixed terminal1. The excitation coil81includes a second end to be connected to the first end of the electric circuitry (circuitry constituting the power supply system200) the second end of which is to be connected to the second fixed terminal2. That is, the excitation coil81is connected in series with a series circuit of the first fixed terminal1, the movable contactor3, and the second fixed terminal2between the first end and the second end of the electric circuitry. Therefore, a current flowing through the movable contactor3also flows through the excitation coil81. The excitation coil81is excited by this current. As shown inFIG. 11, the excitation coil81is wound around a lower portion of the hollow cylindrical body84and the stator83.

The hollow cylindrical body84is made of a non-magnetic metal material. The hollow cylindrical body84includes a hollow cylindrical part formed in a hollow cylindrical shape and a bottom wall (lower wall) for closing one (lower) opening of the hollow cylindrical part. More specifically, the hollow cylindrical body84includes the hollow cylindrical part having a hollow circular cylindrical shape and the bottom wall having a circular shape, and is formed into a bottomed hollow circular cylindrical shape with an open upper surface as a whole. There is a through hole formed in a center of the bottom wall of the housing7. The hollow cylindrical body84is fixed to the bottom wall of the housing7with its upper end (the periphery of the opening) to cover the through hole of the bottom wall of the housing7.

The mover82is a moving iron core also formed in the shape of a cylinder. The mover82is made of a magnetic material. The mover82is accommodated in the hollow cylindrical body84. The mover82is placed inside the hollow cylindrical body84to be movable in the upward/downward direction. In the hollow cylindrical body84, the contact pressure spring42(the holding unit4) is placed between the bottom wall (the upper surface thereof) of the hollow cylindrical body84and the mover82(the lower surface thereof). There is a holding rib841on the upper surface of the bottom wall of the hollow cylindrical body84. The holding rib841is inserted into a lower end of the contact pressure spring42. The mover82is pressed upward by the contact pressure spring42. The mover82is movable between a first position in which the mover82is pressed upward by the contact pressure spring42and is in the upmost position (seeFIG. 11) and a second position in which the mover82compresses the contact pressure spring42and is in the lowermost position (seeFIG. 12). However, the mover82is always held in the first position by a spring force of the contact pressure spring42. The mover82is coupled to the movable contactor3by a shaft831which penetrates through the through hole in the bottom wall of the housing7.

The shaft831is made of a non-magnetic metallic material and has a round bar shape with a length in the upward/downward direction. An upper end of the shaft831is coupled to a center of the movable contactor3. The shaft831passes through the through hole formed in the bottom wall of the housing7and a lower end thereof is coupled to the mover82. Therefore, upward/downward movement of the mover82is transferred to the movable contactor3via the shaft831. The movable contactor3moves in the upward/downward direction in synchronization with the movement of the mover82.

As shown inFIG. 11, when the mover82is in the first position, the first movable contact31and the second movable contact32of the movable contactor3are in contact with the first fixed contact11and the second fixed contact21, respectively. That is, when the mover82is in the first position, the movable contactor3is in the closed position. As shown inFIG. 12, when the mover82is in the second position, the first movable contact31and the second movable contact32of the movable contactor3are separated from the first fixed contact11and the second fixed contact21, respectively. That is, when the mover82is in the second position, the movable contactor3is in the open position (seeFIG. 12).

The stator83is a fixed iron core formed in the shape of a cylinder. The stator83is made of a magnetic material. The stator83is fixed below the bottom wall of the hollow cylindrical body84.

In the trip device8, all of the excitation coil81, the mover82and the stator83have their central axes on the same straight line along the upward/downward direction.

The trip device8moves the mover82from the first position (the position shown inFIG. 11) to the second position (the position shown inFIG. 12) by the magnetic flux generated in the excitation coil81in response to the abnormal current which flows through the movable contactor3and has a value equal to or larger than the prescribed value. At this time, the movable contactor3is pulled by the shaft831to move from the closed position to the open position.

That is, the trip device8moves the mover82to the second position by the magnetic flux generated in the excitation coil81in response to the abnormal current flowing through the movable contactor3, thereby forcibly separating the movable contact (first movable contact)31from the fixed contact (first fixed contact)11. In the present embodiment, at this time, the second movable contact32is also separated from the second fixed contact21. Hereinafter, the operation in which the trip device8forcibly separates the movable contact (first movable contact)31from the fixed contact (first fixed contact)11is referred to as “trip”.

Here, the trip device8does not make trip just when the current flows through the excitation coil81. The trip device8makes trip when an attraction force acting on the mover82from the stator83exceeds the spring force of the contact pressure spring42. The attraction force acting on the mover82from the stator83changes according to the magnitude of the current flowing through the excitation coil81(the load current). The trip device8is configured so that the magnetic attraction force generated by the excitation coil81exceeds the spring force of the contact pressure spring42when the current flowing through the excitation coil81becomes the abnormal current with its value equal to or larger than the prescribed value.

There is a magnet9placed between the stator83and the bottom wall of the hollow cylindrical body84. The magnet9is a permanent magnet and includes on its opposite surfaces in the upward/downward direction a first pole surface and a second pole surface which are different in polarities. The first pole surface (upper surface) of the magnet9is in contact with the bottom wall of the hollow cylindrical body84. The second pole surface (the lower surface) of the magnet9is in contact with the stator83. That is, the magnet9is sandwiched between the stator83and the bottom wall of the hollow cylindrical body84. For example, the first pole surface and the second pole surface may be an N-pole surface and an S-pole face and vice versa.

When the trip device8moves the mover82to the second position, the magnet9holds the mover82in the second position by the magnetic flux generated by the magnet9. That is, the circuit interrupter100of the present embodiment, after the trip device8moves the mover82to the second position, the mover82is held in the second position by the magnetic attraction force generated by the magnet9. In other words, once the trip device8makes trip and the mover82is moved to the second position, the mover82is held (latched) in the second position by the magnet9.

In the present embodiment, the magnet9is placed so that the direction of the magnetic flux generated in the excitation coil81and the direction of the magnetic flux generated in the magnet9are the same in the mover82after the mover82is moved to the second position by the trip device8. That is, when the mover82is in the second position, the magnetic flux generated in the excitation coil81and the magnetic flux generated in the magnet9pass through the mover82. Then, in the present embodiment, the polarities (directions of the pole surfaces) of the magnet9are set to generate the magnetic flux in the same direction as the magnetic flux generated by the excitation coil81in the mover82.

The circuit interrupter100of the present embodiment includes the squib51and the case52in the pyroactuator5of the basic example of embodiment 1, but does not include the piston53. In the circuit interrupter100of the present embodiment, the shape of the case52is different from that of the basic example of embodiment 1. The squib51of the present embodiment is the same as the basic example of embodiment 1 and explanation thereof is omitted.

The case52is made of metal, for example, aluminum or an aluminum alloy. The case52is formed in a bottomed hollow circular cylindrical shape with an open upper surface and a closed lower surface.

The squib51is fitted into a space in an upper portion of the case52. An upper opening of the case52(the inside space thereof) is closed by the squib51. The case52is fixed to the housing7to close the through hole731of the cover member73.

There are two channels50interconnecting the inside and the outside of the case52formed in right and left side portions of the lower surface of the case52. Each channel50includes a first end501connected to the accommodation70and a second end502connected to the inside space of the case52. In the present embodiment, there is no airtight space inside the case52. In the present embodiment, the gas generated in the squib51is directly introduced into the accommodation70(through the inside space of the case52and the channel50).

Each channel50has a circular cylindrical shape having a constant diameter. One of the two channels50(the left channel50inFIGS. 11, 12) guides the gas generated by the squib51to blow into the predetermined space S1between the first movable contact31and the first fixed contact11(seeFIG. 12). The other of the two channels50(the right channel50inFIGS. 11, 12) guides the gas generated by the squib51to blow into the predetermined space S2between the second movable contact32and the second fixed contact21(seeFIG. 12). Each of the two channels50extends obliquely downward from the inside to the outside of the case52.

Next, the operation of the circuit interrupter100having the above-described configuration will be described with reference toFIGS. 11, 12.

In the circuit interrupter100of the present embodiment, the second end of the excitation coil81is connected to the first end of the electric circuitry (e.g., the circuitry constituting the power supply system200) and the second electrode22is connected to the second end of the electric circuitry.

In the normal state of the electric circuitry, the spring force of the contact pressure spring42is greater than the attraction force acting on the mover82from the stator83. Therefore, the movable contactor3is held mainly by this spring force so that the first movable contact31is connected to the first fixed contact11and the second movable contact32is connected to the second fixed contact21(seeFIG. 11). That is, in the normal state of the electric circuitry, the mover82is in the first position farthest from the stator83. Further, in the normal state of the electric circuitry, the movable contactor3is in the closed position where the first movable contact31is in contact with the first fixed contact11and the second movable contact32is in contact with the second fixed contact21. At this time, a current flows from the first end of the electric circuitry to the second end of the electric circuitry by passing through the excitation coil81, the first fixed terminal1, the movable contactor3, and the second fixed terminal2in this order.

On the other hand, when the current flowing through the electric circuitry (the excitation coil81) becomes the abnormal current having its value greater than or equal to the prescribed value (in the abnormal state of the electric circuitry), the attraction force acting on the mover82from the stator83exceeds the spring force of the contact pressure spring42. Thus, the trip device8makes trip and therefore the mover82is moved to the second position and the movable contactor3is moved to the open position. As a result, the circuit between the first fixed terminal1and the second fixed terminal2is interrupted and the current flowing through the circuit between the first fixed terminal1and the second fixed terminal2is interrupted.

Further, when the current flowing through the electric circuitry (the excitation coil81) becomes the abnormal current with its value greater than or equal to the prescribed value, the control circuitry207detects the abnormal current by the current sensor206, for example. Upon detecting the abnormal current, the control circuitry207makes a current flow across the pair of pin electrodes54of the squib51to energize the heating element515. Thus, the explosive of the combustion part513is combusted to generate a large amount of gas and the low strength portion of the lower wall of the metal sleeve512is broken by the pressure of the gas and the gas is discharged to the inside space of the case52through the broken portion.

The gas generated by the squib51is introduced into the accommodation70through the channel50of the case52. The gas introduced into the accommodation70goes to the predetermined space S1between the first movable contact31and the first fixed contact11or the predetermined space S2between the second movable contact32and the second fixed contact21(see arrow W3inFIG. 12).

Even in the circuit interrupter100of the present embodiment, the gas generated by the squib51(electrically insulating gas) is introduced into the accommodation70, thereby increasing the pressure of the accommodation70. Accordingly, the arc generated between the contacts is cooled. Therefore, the electrically insulating properties of the plasma of the arc discharge or the metal vapor is enhanced and the extinction of the arc is promoted.

Further, the gas introduced from the channel50into the accommodation70blows into the predetermined space S1between the first movable contact31and the first fixed contact11, or the predetermined space S2between the second movable contact32and the second fixed contact21. Thus, the arc generated between the contacts is cooled and the arc extinction is promoted.

Thus, even in the circuit interrupter100of the present embodiment, the gas generated by the squib51is introduced into the predetermined spaces S1, S2. Thereby, it is possible to quickly extinguish the arc.

Incidentally, the timing at which the trip device8makes trip may be prior or subsequent to the timing at which the squib51starts to release the gas. The gas may be released from the squib51before the trip device8makes trip. The gas may be released from the squib51after the trip device8makes trip. The release and the trip may occur at the same time. It is preferable that the gas is released from the squib51after the trip device8makes trip.

The circuit interrupter100of variation 1 of embodiment 2 will be described with reference toFIGS. 13-15.FIG. 13is a cross-sectional view of primary part of the circuit interrupter100of variation 1 before operation.FIG. 14is a side view in a direction perpendicular to the sheet ofFIG. 13(from the right), of the primary part of the circuit interrupter100of variation 1 before operation.FIG. 15is a side view in the same direction asFIG. 14, of the primary part of the circuit interrupter100of variation 1 after operation. Hereinafter, the circuit interrupter100of embodiment 2 is also referred to as the circuit interrupter100of the basic example of embodiment 2.

As shown inFIGS. 13, 14, the circuit interrupter100of variation 1 includes only one set of the movable contact31and the fixed contact11in the circuit interconnecting the first electrode12and the second electrode22. Specifically, the first fixed terminal1is a plate-shaped member made of a metal material having conductivity. The first fixed terminal1includes a first fixed contact11at a first end (a left end inFIG. 14) and a second end thereof (a right end inFIG. 14) functions as the first electrode12. The second fixed terminal2is a plate-shaped member which is made of a metal material having conductivity and is shorter than the first fixed terminal1. The second fixed terminal2is placed to face the first fixed terminal1in the upward/downward direction. The second fixed terminal2includes a first end (a right end inFIG. 14) which functions as the second electrode22. The movable contactor3includes at a first end (a left end inFIG. 14) the movable contact31connected to the fixed contact11. The movable contactor3and the second fixed terminal2are not interconnected by a contact set including a set of a movable contact and a fixed contact, but are interconnected by a braided wire87made by braiding copper wires.

The case52accommodating the squib51includes only one channel50at the center of its bottom wall. Then, the case52is placed to allow the first end501of the channel50to face the predetermined space S1between the movable contact31and the fixed contact11(seeFIG. 15). As a result, the gas is introduced in a direction orthogonal to the predetermined space S1.

Although there is no illustration, similarly to the basic example of embodiment 2, the circuit interrupter100of variation 1 also includes the housing7accommodating therein the first fixed contact11, the movable contactor3, and the upper end of the shaft831. The squib51and the case52, the braided wire87, and part (left part) of the second fixed terminal2are also placed inside the housing7(the accommodation70).

In the present variation, when the abnormal current flows in the electric circuitry, the excitation coil81is excited to move the mover82from the first position (the position shown inFIG. 14) to the second position (the position shown inFIG. 15). Along with this, the movable contactor3is moved from the open position (the position shown inFIG. 14) to the open position (the position shown inFIG. 15). Further, when the control circuitry207provides a current to the squib51, the gas is generated from the squib51and the gas is blown into the predetermined space S1between the movable contact31and the fixed contact11. As a result, the arc generated between the contacts is cooled and therefore it is possible to quickly extinguish the arc.

Incidentally, similarly to the basic example of embodiment 2, the circuit interrupter100of the present variation may include the magnet9for holding the mover82at the second position.

The circuit interrupter100of variation 2 of embodiment 2 will be described with reference toFIGS. 16, 17.

The circuit interrupter100of the present variation is different from the circuit interrupter100of the basic example of embodiment 2 in including permanent magnets43as the holding unit4instead of the contact pressure contact spring41. The other configurations are same as those of the circuit interrupter100of the basic example of embodiment 2 and therefore explanations thereof are omitted.

In the circuit interrupter100of the present variation, as shown inFIG. 17, the movable contactor3is formed to have a cross shape in a top view and includes a body part33and a pair of protrusion parts34. The body part33has a length in the rightward/leftward direction and includes the first movable contact31and the second movable contact32at both ends in the length direction. The pair of protrusion parts34protrude in the forward/backward direction from side surfaces of the body part33. Each of the protruding parts34of the movable contactor3is provided with a permanent magnet43. As shown inFIG. 16, the center of the movable contactor3faces the bottom surface of the case52. Further, a pair of magnetic members (not shown), in particular iron pieces are provided to the lower surface of the cover member73of the housing7to be in front and back of the case52(positions facing the permanent magnets43).

In variation 2, the iron pieces are attracted by the permanent magnets43. The first movable contact31and the second movable contact32are connected to the first fixed contact11and the second fixed contact21while the iron pieces and the permanent magnets43are separated from each other (seeFIG. 16).

Also in the present variation, when the trip device8makes trip, the mover82is moved from the first position (the position shown inFIG. 16) to the second position against the magnetic attraction force between the iron pieces and the permanent magnets43, and the movable contactor3is moved from the closed position (the position shown inFIG. 16) to the open position. Thus, the circuit between the first fixed terminal1and the second fixed terminal2is interrupted. At this time, the control circuitry207allows the squib51to generate the gas and also allows the gas to be introduced into the accommodation70. As a result, the arc generated between the contacts is cooled and therefore it is possible to quickly extinguish the arc.

In the present variation, the magnetic member may be provided to the movable contactor3and the permanent magnet43may be provided to the cover member73of the housing7. Further, a spacer may be provided between the permanent magnet43and the magnetic member. The movable contactor3may be maintained in the closed state while the permanent magnet43is in direct contact with the magnetic member. Further, the holding unit4may include both the contact pressure spring41and the permanent magnet43.

The circuit interrupter100of variation 3 of embodiment 2 will be described with reference toFIG. 18.

The circuit interrupter100of the present variation is mainly different from the circuit interrupter100of the basic example of embodiment 2 in including as the trip device8, a bimetallic plate88instead of the excitation coil81, the mover82, the stator83, and the hollow cylindrical body84. The other configurations are same as those of the circuit interrupter100of the basic example of embodiment 2 and therefore explanations thereof are omitted.

In the circuit interrupter100of the present variation, as shown inFIG. 18, the movable contactor3is held in the closed position by the contact pressure spring41similarly to the basic example of embodiment 1. Further, the bimetallic plates88are attached to the lower surfaces of the first fixed terminal1and the second fixed terminal2with metal plates89in-between. The bimetallic plate88has its lower surface in contact with the upper surface of the movable contactor3.

In the present variation, when the abnormal current flows in the movable contactor3, the bimetallic plate88is curved downward (see the dotted line inFIG. 18). Thus, the movable contactor3is moved from the closed position to the open position.

That is, in the circuit interrupter100of the present variation, when the abnormal current flows in the circuit including the movable contact (first movable contact)31and the fixed contact (first fixed contact)11, the bimetallic plate88is curved and thereby the movable contactor3is moved to the open position.

Thus, it is possible to interrupt the circuit between the first fixed terminal1and the second fixed terminal2.

The present variation may be provided with a holding mechanism for holding the movable contactor3in the open position after the movable contactor3is moved to the open position by the bimetallic plate88. For example, the holding mechanism may be a combination of a permanent magnet and a magnetic member provided to the movable contactor3and the inside wall of the housing7. Further, the trip device8may include the bimetallic plate88in addition to the excitation coil81, the mover82, the stator83and the hollow cylindrical body84.

The circuit interrupters100of the basic example and variations 1-3 of embodiment 2 may also include the yokes61,62similarly to embodiment 1.

(3) Other Variations

The application of the circuit interrupter100is not limited to a fuse for the vehicle300. The circuit interrupter100may be used for interrupting any electric circuitry through which a large current, such as, for example, a short circuit current may flow. Further, the circuit interrupter100may be a relay (electromagnetic relay) including an electromagnet device.

A guide for defining the moving direction of the movable contactor3may be formed in the accommodation70of the housing7. The guide may be formed on the inner wall of the accommodation70to be long in the upward/downward direction to be in contact with the side surface of the movable contactor3along the moving direction of the movable contactor3. Thus, when the movable contactor3is moved by the pyroactuator5, the movable contactor3is less likely to tilt. The guide may be a rod extending upward from the bottom surface of the accommodation70and penetrating the movable contactor3.

The configurations of the basic examples and individual variations of embodiments 1, 2 can be appropriately combined.

Referring toFIGS. 19-21, the circuit interrupter100according to one concrete example (concrete example 1) of one variation obtained by combining embodiments 1, 2 will be described. The circuit interrupter100of the present concrete example functions as a so-called normally-on (“b” contact) device. The circuit interrupter100includes the excitation coil81, the squib51, and the moving mechanism.

As shown inFIG. 19, the fixed contact (first fixed contact)11of the fixed terminal1(first fixed terminal)1, the second fixed contact21of the second fixed terminal2, and the movable contactor3including the movable contact (first movable contact)31and the second movable contact32are accommodated inside the housing7. The squib51is placed to face the upper surface of the movable contactor3. The housing7includes the through hole at its bottom wall and the hollow cylindrical body84is fixed to cover the through holes in the bottom wall. Further, the shaft831having its upper end coupled to the movable contactor3is placed so that the lower end thereof passes through the through hole in the bottom wall of the housing7and is exposed inside the hollow cylindrical body84. The mover82and the contact pressure spring42are placed inside the hollow cylindrical body84. The mover82is coupled to the lower end of the shaft831. The stator83is fixed below the bottom wall of the hollow cylindrical body84. The excitation coil81is placed to surround the peripheries of the mover82and the stator83.

The movable contactor3is held by the spring force from the contact pressure spring42and the like in the closed position in which the movable contact (first movable contact)31is in contact with the fixed contact (first fixed contact)11(seeFIG. 19).

The excitation coil81and energization thereof are controlled by the control circuitry200. When the excitation coil81is energized, the magnetic flux generated by the excitation coil81moves the mover82downward. When the mover82moves downward, the shaft831and the movable contactor3also move downward together with the mover82. Thereby, the movable contactor3is moved from the closed position (seeFIG. 19) to the first open position (seeFIG. 20). On the other hand, when the energization of the excitation coil81is stopped, the mover82is moved upward by the spring force of the contact pressure spring42and the like. The movable contactor3is moved to the closed position (seeFIG. 19).

The moving mechanism includes a space interconnecting the squib51and the movable contactor3(a space between the squib51and the movable contactor3). That is, the circuit interrupter100of the present concrete example allows the movable contactor3to receive the pressure of the gas generated in the squib51directly (the movable contactor3forms part of the outer wall of the pressurized chamber520) and allows the movable contactor3to be moved directly by the pressure of the gas from the squib51. The moving mechanism moves the movable contactor3from the closed position (seeFIG. 19) or the first open position (seeFIG. 20) to a second open position in which the movable contact (first movable contact)31is separated from the fixed contact (first fixed contact)11(seeFIG. 21). The second open position here is a position of the movable contactor3in which the movable contact (first movable contact)31is farther away from the fixed contact (first fixed contact)11than in the case where the movable contactor3is in the first open position. That is, in the present concrete example, a distance between the closed position and the second open position is longer than a distance between the closed position and the first open position. When the movable contactor3moves downward to the second open position, the mover82also moves downward. The mover82is held (latched) in the position shown inFIG. 21by the magnetic flux generated by the magnet9.

Referring toFIGS. 22, 23, the circuit interrupter100according to another concrete example (concrete example 2) of one variation obtained by combining embodiments 1, 2 will be described. The circuit interrupter100of the present concrete example functions as a so-called normally-off (“a” contact) device. Similarly to the circuit interrupter100of concrete example 1, the circuit interrupter100includes the excitation coil81, the squib51, and the moving mechanism. Hereinafter, a description will be given centering on different points from concrete example 1 described above.

In the circuit interrupter100shown inFIG. 22, the stator83is fixed to the bottom wall of the housing7inside the hollow cylindrical body84. The stator83includes at its center a through hole extending in the upward/downward direction. The lower end of the shaft831extends downward while passing through the through hole of the bottom wall of the housing7and the through hole of the stator83, and is fixed to the mover82. A return spring85is placed between the mover82and the stator83. The excitation coil81is placed to surround the peripheries of the mover82and the stator83.

The movable contactor3is held by the spring force received by the mover82from the return spring85and the like in the first open position where the movable contact (first movable contact)31is separated from the fixed contact (first fixed contact)11(seeFIG. 22).

When the excitation coil81is energized, the magnetic flux generated by the excitation coil81moves the mover82upward. When the mover82moves upward, the shaft831and the movable contactor3also move upward together with the mover82. Thereby, the movable contactor3is moved from the first open position (seeFIG. 22) to the closed position (seeFIG. 23). On the other hand, when the energization of the excitation coil81is stopped, the mover82is moved downward by the spring force of the return spring85and the like. The movable contactor3is moved to the first open position (seeFIG. 22). That is, the circuit interrupter100of the present concrete example functions as a so-called “a” contact type contact device.

The moving mechanism is defined by a space interconnecting the squib51and the movable contactor3(a space between the squib51and the movable contactor3). That is, the movable contactor3directly receives the pressure of the gas from the squib51and then is moved. The moving mechanism is configured to move the movable contactor3to the second open position where the movable contact (first movable contact)31is separated from the fixed contact (first fixed contact)11(seeFIG. 22). The second open position here is the same as the first open position. That is, in the present concrete example, the distance between the closed position and the second open position is equal to the distance between the closed position and the first open position. When the movable contactor3moves downward to the second open position, the mover82also moves downward.

Referring toFIGS. 24, 25, the circuit interrupter100according to another concrete example (concrete example 3) of one variation obtained by combining embodiments 1, 2 will be described. The circuit interrupter100of the present concrete example includes a structure of the circuit interrupter100of the basic example of embodiment 2 (seeFIG. 11), but the pyroactuator5thereof is replaced with the pyroactuator5(the pyroactuator5including the piston53; seeFIG. 9) of one variation of embodiment 1.

In the circuit interrupter100of the present concrete example, when the gas is generated in the squib51, the movable contactor3is pressed with the piston53which is moved by the pressure in the pressurized chamber520. Thereby, the movable contactor3is moved to the open position. Further, in the circuit interrupter100of the present concrete example, the movable contactor3can be moved to the open position by also the electromagnetic force generated by the magnetic flux caused by the excitation coil81when the abnormal current flows in the excitation coil81of the trip device8.FIG. 24is a view of the circuit interrupter100of the present concrete example and shows a state where both the squib51and the trip device8do not operate.FIG. 25is a view of the circuit interrupter100of the present concrete example and shows a state in which the piston53is pressed by the pressure of the gas from the squib51and the movable contactor3is pressed by the piston53to move to the open position.

Referring toFIGS. 26-28, the circuit interrupter100according to another concrete example (concrete example 4) of one variation obtained by combining embodiments 1, 2 will be described. The circuit interrupter100of the present concrete example includes a structure of the circuit interrupter100of concrete example 1 (seeFIG. 19), but the pyroactuator5thereof is replaced with the pyroactuator5(seeFIG. 9) of one variation of embodiment 1.

In the circuit interrupter100of the present concrete example, the movable contactor3moves between the closed position (seeFIG. 26) and the first open position (seeFIG. 27) in response to switching on and off of the energization of the excitation coil81. That is, while the excitation coil81is not energized, the movable contactor3is held by the spring force from the contact pressure spring42and the like in the closed position where the movable contact (first movable contact)31is in contact with the fixed contact (first fixed contact)11. Further, when the excitation coil81is energized, the movable contactor3is held by the electromagnetic force due to the magnetic flux generated in the excitation coil81in the first open position where the movable contact (first movable contact)31is separated from the fixed contact (first fixed contact)11. Further, when the pyroactuator5is activated and the squib51generates the gas, the piston53is pressed downward by the pressure in the pressurized chamber520and the movable contactor3is pressed by the piston53to be moved to the second open position (seeFIG. 28).

Referring toFIGS. 29-31, the circuit interrupter100according to another concrete example (concrete example 5) of one variation obtained by combining embodiments 1, 2 will be described. The circuit interrupter100of the present concrete example includes a structure of the circuit interrupter100of concrete example 2 (seeFIG. 22), but the pyroactuator5thereof is replaced with the pyroactuator5(seeFIG. 9) of one variation of embodiment 1.

In the circuit interrupter100of the present concrete example, the movable contactor3moves between the closed position (seeFIG. 30) and the first open position (seeFIG. 29) in response to switching on and off of the energization of the excitation coil81. That is, while the excitation coil81is not energized, the movable contactor3is held by the spring force from the return spring85and the like in the first open position where the movable contact (first movable contact)31is separated from the fixed contact (first fixed contact)11. When the excitation coil81is energized, the movable contactor3is held by the electromagnetic force due to the magnetic flux generated in the excitation coil81in the closed position where the movable contact (first movable contact)31is in contact with the fixed contact (first fixed contact)11. Further, when the pyroactuator5is activated and the squib51generates the gas, the piston53is pressed downward by the pressure in the pressurized chamber520and the movable contactor3is pressed by the piston53to be moved to the second open position (seeFIG. 31). Here, the second open position is the same as the first open position.

In the circuit interrupters100of concrete examples 1-5, the gas generated by the squib51is introduced into the accommodation70of the housing7, thereby promoting the arc extinction.

Further, in concrete examples 1, 2, 4, 5, while the pyroactuator5is not activated, the circuit interrupter100can be used as an electromagnetic relay including a contact device.

The relationship among the closed position, the first open position, and the second open position is not limited to the positional relationship shown in each of the above-described concrete examples. That is, the distance between the closed position and the first open position may be longer than, shorter than, or equal to the distance between the closed position and the second open position. The distance between the closed position and the second open position is preferably longer than the distance between the closed position and the first open position.

In addition, the circuit interrupters100of concrete examples 3-5 may include the pyroactuator5of the basic example of embodiment 1.

In each concrete example, the case52may include, as the detent mechanism, the second cylindrical portion (a portion having a frustoconical inner surface whose diameter decreases toward the lower side) and the third cylindrical portion (a portion having a cylindrical inner surface having a smaller diameter than the base533of the piston53).

Further, in each concrete example described above, the circuit interrupter100may include a holder and a contact pressure spring. The holder has a rectangular box shape with open left and right surfaces to allow the movable contactor3to pass therethrough to penetrate in the rightward/leftward direction. The upper end of the shaft831is coupled to a lower wall of the holder. The contact pressure spring is placed inside the holder to be positioned between an upper surface of the lower wall of the holder and the lower surface of the movable contactor3, thereby biasing the movable contactor3upward. With this configuration, it is possible to ensure a contact pressure between the movable contact (first movable contact)31and the fixed contact (first fixed contact)11and a contact pressure between the second movable contact32and the second fixed contact21while the movable contactor3is in the closed position.

As apparent from the aforementioned embodiments and variations, a circuit interrupter (100) of a first aspect includes a fixed terminal (1), a movable contactor (3), a moving mechanism, a squib (51), and accommodation (70). The fixed terminal (1) includes a fixed contact (11). The movable contactor (3) includes a movable contact (31) connected to the fixed contact (11). The moving mechanism is configured to move the movable contactor (3) from a closed position to an open position. The closed position is a position of the movable contactor (3) where the movable contact (31) is connected to the fixed contact (11). The open position is a position of the movable contactor (3) where the movable contact (31) is separated from the fixed contact (11). The squib (51) is configured to generate gas by combustion. The accommodation (70) is for accommodating the fixed contact (11) and the movable contactor (3). In the circuit interrupter (100), the gas is introduced into the accommodation (70).

According to the first aspect, the gas generated by the squib (51) is introduced into the accommodation (70) accommodating the fixed contact (11) and the movable contactor (3). Therefore, even when the arc is developed between the contacts, it is possible to quickly extinguish the arc by the gas.

In a circuit interrupter (100) of a second aspect referring to the first aspect, the gas is introduced into a predetermined space (S1) between the fixed contact (11) and the movable contact (31) while the movable contactor (3) is in the open position.

According to the second aspect, the gas generated by the squib (51) is introduced into the predetermined space (S1) between the fixed contact (11) and the movable contact (31) of the movable contactor (3) in the open position. Therefore, even when the arc is developed between the contacts, it is possible to quickly extinguish the arc by the gas.

A circuit interrupter (100) of a third aspect referring to the second aspect includes a channel (50) for guiding the gas to allow the gas to blow into the predetermined space (S1).

According to the third aspect, the gas blows into the arc via the channel (50). It is possible to promote the arc extinction.

In a circuit interrupter (100) of a fourth aspect referring to the second or third aspect, the gas is introduced in a direction perpendicular to the predetermined space (S1).

According to the fourth aspect, it is possible to deform or stretch the arc developed in the predetermined space (S1) efficiently. Thus, it is possible to promote the arc extinction and to improve the interruption performance.

In a circuit interrupter (100) of a fifth aspect referring to any one of the first to fourth aspects, the moving mechanism includes a pressurized chamber (520) and a piston (53). The pressurized chamber (520) is for receiving pressure of the gas. The piston (53) is for receiving pressure inside the pressurized chamber (520) and moving the movable contactor (3) in the closed position by applying a force to the movable contactor (3) in a direction toward the open position. In the circuit interrupter (100), part of the gas is introduced into the predetermined space (S1) from the pressurized chamber (520).

According to the fifth aspect, it is possible to move the movable contactor (3) with the pressure of the gas (energy) and also possible to quickly extinguish the arc generated between the contacts by introduction of the gas into the predetermined space (S1).

In a circuit interrupter (100) of a sixth aspect referring to any one of the first to fourth aspects, the moving mechanism includes a trip device (8). The trip device (8) is for moving the movable contactor (3) from the closed position to the open position in response to an abnormal current flowing through a circuit including the movable contact (31) and the fixed contact (11).

According to the sixth aspect, as to the device using the trip device (8) to interrupt the circuit (e.g., a relay), it is possible to quickly extinguish the arc developed between the contacts.

In a circuit interrupter (100) of a seventh aspect referring to the sixth aspect, the trip device (8) includes an excitation coil (81) constituting part of the circuit. The trip device (8) is configured to move the movable contactor (3) to the open position by an electromagnetic force developed by a magnetic flux caused by the excitation coil (81) in response to a flow of the abnormal current through the circuit.

According to the seventh aspect, as to the device using the electromagnetic force generated by the magnetic flux generated in the excitation coil (81), it is possible to quickly extinguish the arc developed between the contacts.

In a circuit interrupter (100) of an eighth aspect referring to the sixth or seventh aspect, the trip device (8) includes a bimetallic plate (88) which curves in response to a flow of the abnormal current through the circuit. The trip device (8) is configured to move the movable contactor (3) to the open position when the bimetallic plate (88) curves in response to a flow of the abnormal current through the circuit.

According to the eighth aspect, as to the device making the bimetallic plate (88) curve to interrupt the circuit, it is possible to quickly extinguish the arc developed between the contacts.

A circuit interrupter (100) of a ninth aspect referring to any one of the first to eighth aspects includes an elastic part (contact pressure springs41,42) for providing an elastic force in a direction toward the closed position, to the movable contactor (3).

According to the ninth aspect, it is possible to hold the movable contactor (3) in the closed position.

A circuit interrupter (100) of a tenth aspect referring to any one of the first to ninth aspects includes a permanent magnet (43) for holding the movable contactor (3) in the closed position.

According to the tenth aspect, it is possible to hold the movable contactor (3) in the closed position.

A circuit interrupter (100) of an eleventh aspect referring to any one of the first to tenth aspects includes a space which includes the accommodation (70) and in which the gas is sealed.

According to the eleventh aspect, the gas is introduced into the space in which the gas is sealed and thus the pressure in this space is increased. Accordingly, it is possible to quickly extinguish the arc developed between the contacts.

A circuit interrupter (100) of a twelfth aspect includes a fixed terminal (1), a movable contactor (3), an excitation coil (81), and a moving mechanism. The fixed terminal (1) includes a fixed contact (11). The movable contactor (3) includes a movable contact (31) connected to the fixed contact (11). The squib (51) is configured to generate gas by combustion. The excitation coil (81) is configured to move the movable contactor (3) from a closed position where the movable contact (31) is connected to the fixed contact (11) to a first open position where the movable contact (31) is separated from the fixed contact (11). The moving mechanism is configured to move the movable contactor (3) to a second open position where the movable contact (31) is separated from the fixed contact (11).

Configurations according to the second to eleventh aspects are optional configurations for the circuit interrupter (100) and can be omitted appropriately.

REFERENCE SIGNS LIST