Contact device

A contact device includes a fixed contact, a movable contact, a housing, and an arc extinguishing member. The movable contact moves between a closed position where the movable contact contacts the fixed contact and an open position where the movable contact is separate from fixed contact. The housing houses the fixed contact and the movable contact. The arc extinguishing member is movably disposed in the housing and discharges an arc extinguishing gas. The arc extinguishing member is disposed facing a gap between the fixed contact and the movable contact when the movable contact is in the open position.

CROSS-REFERENCE TO RELATED APPLICATION

This application is the U.S. National Phase of International Application No. PCT/JP2019/040570, filed on Oct. 16, 2019. This application claims priority to Japanese Patent Application No. 2018-215493, filed Nov. 16, 2018. The contents of those applications are incorporated by reference herein in their entireties.

FIELD

The present invention relates to a contact device.

BACKGROUND

A contact device includes a fixed contact and a movable contact. The movable contact moves between a closed position where the movable contact contacts the fixed contact and an open position where the movable contact is separate from the fixed contact. When the movable contact separates from the fixed contact, an arc is generated between the contacts. Conventionally, as described in Japanese Laid-Open Patent Publication No. 2015-49939, there is known a contact device including an arc extinguishing member disposed in a space where the contacts are housed in order to quickly extinguish an arc. The arc extinguishing member discharges an arc extinguishing gas by utilizing heat of the arc. The arc extinguishing gas extinguishes the arc, thereby improving breakdown performance of the contact device.

SUMMARY

In order to improve arc extinguishing performance owing to the arc extinguishing gas, it is desirable that the arc extinguishing member is disposed proximate to a gap between the fixed contact and the movable contact. However, if the arc extinguishing member is disposed proximate to the gap between the contacts, a space between the arc extinguishing member and the contacts becomes narrow. Thus, the arc is less likely to pass through the space and stays. This makes it difficult for the arc to be extinguished quickly.

An object of the present invention is to improve the arc extinguishing performance owing to the arc extinguishing gas.

A contact device according to one aspect of the present invention includes a fixed contact, a movable contact, a housing, and an arc extinguishing member. The movable contact moves between a closed position where the movable contact contacts the fixed contact and an open position where the movable contact is separate from the fixed contact. The housing houses the fixed contact and the movable contact. The arc extinguishing member is movably disposed in the housing and discharges an arc extinguishing gas. The arc extinguishing member is disposed facing a gap between the fixed contact and the movable contact when the movable contact is in the open position.

In the contact device according to the present aspect, the arc extinguishing member is movably disposed in the housing. Therefore, when the arc extinguishing gas is generated, the arc extinguishing gas causes an increase in pressure, whereby the arc extinguishing member moves. Thus, even if the arc extinguishing member is disposed proximate to the gap, a large space can be secured between the contacts and the arc extinguishing member. Accordingly, an arc extinguishing gas can be generated proximate to the gap between the contacts and an arc can easily pass through a space between the contacts and the arc extinguishing member. As a result, the arc is easily extended and quickly extinguished. Therefore, the arc extinguishing performance owing to the arc extinguishing gas can be improved.

The arc extinguishing member may be configured to move at least in a direction in which the arc extinguishing member separates from the fixed contact. In this case, the arc extinguishing member can move toward the direction in which the arc extinguishing member separates from the fixed contact due to the pressure increase caused by the arc extinguishing gas. Therefore, even if the arc extinguishing member is disposed proximate to the gap, a large space can be secured between the fixed contact and the arc extinguishing member.

The arc extinguishing member may be configured to move at least in a direction in which the arc extinguishing member separates from the movable contact. In this case, the arc extinguishing member can move toward the direction in which the arc extinguishing member separates from the movable contact due to the pressure increase caused by the arc extinguishing gas. Therefore, even if the arc extinguishing member is disposed proximate to the gap, a large space can be secured between the movable contact and the arc extinguishing member.

The arc extinguishing member may have a shape that tapers toward the gap. In this case, even if the arc extinguishing member is disposed proximate to the gap, a large space can be secured between the contacts and the arc extinguishing member. Thus, the arc extinguishing performance can be further improved.

The contact device may further include a support member that supports the arc extinguishing member such that the arc extinguishing member is movable. The support member may have a spring characteristic. In this case, the support member can support the arc extinguishing member such that the arc extinguishing member is movable owing to the spring characteristic of the support member. The support member may be a coil spring. The support member may be a leaf spring.

At least a part of the arc extinguishing member may have a spring characteristic. In this case, the arc extinguishing member can be movably provided owing to the spring characteristic of the arc extinguishing member.

In a direction from the arc extinguishing member toward the gap, a distance between a tip of the arc extinguishing member and the fixed contact may be smaller than a distance from the housing to the tip of the arc extinguishing member. In this case, the tip of the arc extinguishing member can be disposed proximate to the fixed contact. Thus, the arc extinguishing performance can be improved.

In the direction from the arc extinguishing member toward the gap, a distance between the tip of the arc extinguishing member and the movable contact may be smaller than the distance from the housing to the tip of the arc extinguishing member. In this case, the tip of the arc extinguishing member can be disposed proximate to the movable contact. Thus, the arc extinguishing performance can be improved.

DETAILED DESCRIPTION

Hereinafter, a relay1aaccording to an embodiment will be described with reference to the drawings.FIG. 1is a side sectional view of the relay1aaccording to the embodiment. As illustrated inFIG. 1, the relay1aincludes a contact device2, a housing3, and a drive device4. In the following description, the up, down, left, and right directions indicate the up, down, left, and, right directions inFIG. 1. Specifically, a direction from the drive device4toward the contact device2is defined as an upper direction. A direction from the contact device2toward the drive device4is defined as a lower direction. InFIG. 1, a direction that intersects an upper and lower direction is defined as a left-right direction. A direction that intersects the upper and lower direction and the left-right direction is defined as a front-back direction. The front-back direction is a direction perpendicular to the sheet ofFIG. 1. However, these directions are defined for convenience of description and are not intended to limit the directions in which the relay1ais disposed.

The contact device2includes a movable mechanism10, a first fixed terminal11, a second fixed terminal12, a movable contact piece13, a first movable contact16, and a second movable contact17. The first fixed terminal11and the second fixed terminal12are made from a conductive material such as copper, for example. The first fixed terminal11is provided with a first fixed contact14. The second fixed terminal12is provided with a second fixed contact15. The first fixed contact14and the second fixed contact15are disposed apart from each other in the left-right direction.

The first fixed terminal11includes a first contact support portion21and a first external terminal portion22. The first fixed contact14is connected to the first contact support portion21. The first external terminal portion22is connected to the first contact support portion21. The first external terminal portion22protrudes outward from the housing3. The second fixed terminal12includes a second contact support portion23and a second external terminal portion24. The second fixed contact15is connected to the second contact support portion23. The second external terminal portion24is connected to the second contact support portion23. The second external terminal portion24protrudes outward from the housing3.

InFIG. 1, the first external terminal portion22and the second external terminal portion24protrude toward the upper direction from the housing3. However, the direction toward which the first external terminal portion22and the second external terminal portion24protrude is not limited to the upper and lower direction. The first external terminal portion22and the second external terminal portion24may protrude from the housing3toward any direction such as the left-right direction, the front-back direction, or the like.

The movable contact piece13is made from a conductive material such as copper, for example. The movable contact piece13extends in the left-right direction. In the present embodiment, the longitudinal direction of the movable contact piece13coincides with the left-right direction. The movable contact piece13is disposed facing the first fixed terminal11and the second fixed terminal12in the upper and lower direction.

The movable contact piece13is arranged to be movable in a contact direction Z1and a separation direction Z2. The contact direction Z1is a direction in which the movable contact piece13approaches the first fixed terminal11and the second fixed terminal12(the upper direction inFIG. 1). The separation direction Z2is a direction in which the movable contact piece13separates from the first fixed terminal11and the second fixed terminal12(the lower direction inFIG. 1).

The first movable contact16and the second movable contact17are supported by the movable contact piece13. The first movable contact16and the second movable contact17are disposed apart from each other in the left-right direction. The first movable contact16faces the first fixed contact14in the upper and lower direction. The second movable contact17faces the second fixed contact15in the upper and lower direction.

The movable mechanism10is disposed such as to be movable in the contact direction Z1and the separation direction Z2together with the movable contact piece13. The movable mechanism10includes a drive shaft19, a holder26, and a contact spring27. The drive shaft19extends in the upper and lower direction. The drive shaft19is connected to the movable contact piece13. The drive shaft19extends toward the lower direction from the movable contact piece13. The drive shaft19is connected to the movable contact piece13via the holder26and the contact spring27. The holder26is attached to the movable contact piece13and holds the movable contact piece13. The contact spring27is disposed between the holder26and the movable contact piece13. The contact spring27urges the movable contact piece13toward the contact direction Z1in a state where the movable contacts16and17contact the fixed contacts14and15.

The housing3houses the contact device2and the drive device4. The housing3includes a first housing3aand a second housing3b. The first housing3aincludes a first storage portion S1. The second housing3bincludes a second storage portion S2. The first storage portion S1and the second storage portion S2are partitioned by a partition wall46. The fixed contacts14and15, the movable contact piece13, and the movable contacts16and17are disposed in the first storage portion S1. The drive device4is disposed in the second storage portion S2.

The first housing3aincludes a top surface41, a first side surface42, and a second side surface43. The top surface41faces the movable contact piece13in a moving direction of the movable mechanism10. The top surface41is disposed in the upper direction of the movable contact piece13. The first side surface42and the second side surface43are disposed spaced apart from each other in the left-right direction. The first side surface42and the second side surface43face the movable contact piece13in a direction that intersects the moving direction of the movable mechanism10. That is, the first side surface42and the second side surface43face the movable contact piece13in the left-right direction. The first side surface42and the second side surface43extend in the moving direction of the movable mechanism10. The movable contact piece13is disposed between the first side surface42and the second side surface43in the left-right direction.

The drive device4operates the movable contact piece13by electromagnetic force. The drive device4moves the movable contact piece13in the contact direction Z1and the separation direction Z2. The drive device4is disposed in the lower direction of the housing3. The drive device4includes a spool30, a movable iron core31, a coil32, a fixed iron core33, a yoke34, and a return spring35.

The spool30includes a hole301that penetrates the spool30in the upper and lower direction. The movable iron core31is disposed in the hole301of the spool30. The movable iron core31is provided separately from the fixed iron core33. The movable iron core31is connected to the drive shaft19. The movable iron core31is configured to move in the contact direction Z1and the separation direction Z2. The coil32is wound around the spool30. The coil32is energized to generate electromagnetic force that moves the movable iron core31toward the contact direction Z1.

The fixed iron core33is disposed in the hole301of the spool30. The fixed iron core33is disposed facing the movable iron core31. The return spring35is disposed between the movable iron core31and the fixed iron core33. The return spring35urges the movable iron core31toward the separation direction Z2.

The yoke34is disposed to surround the coil32. The yoke34is disposed on a magnetic circuit formed by the coil32. Portions of the yoke34are disposed in the upper direction of the coil32, to the sides of the coil32, and in the lower direction of the coil32.

Next, an operation of the relay1awill be described. When the coil32is not energized, the drive device4is not magnetized. In this case, the drive shaft19is pressed toward the separation direction Z2together with the movable iron core31by elastic force of the return spring35. Therefore, the movable contact piece13is also pressed toward the separation direction Z2, and the movable contacts16and17are in their open positions illustrated inFIG. 1. In the state where the movable contacts16and17are in the open positions, the first movable contact16and the second movable contact17are separate from the first fixed contact14and the second fixed contact15.

When the coil32is energized, the drive device4is magnetized. In this case, electromagnetic force of the coil32causes the movable iron core31to move toward the contact direction Z1against the elastic force of the return spring35. As a result, both the drive shaft19and the movable contact piece13move toward the contact direction Z1, and the movable contacts16and17move to their closed positions illustrated inFIG. 2. In the state where the movable contacts16and17are in the closed positions, the first movable contact16and the second movable contact17contact the first fixed contact14and the second fixed contact15, respectively.

When a current to the coil32is stopped and the coil is demagnetized, the movable iron core31is pressed toward the separation direction Z2by the elastic force of the return spring35. As a result, both the drive shaft19and the movable contact piece13move toward the separation direction Z2, and the movable contacts16and17return to the open positions illustrated inFIG. 1.

As illustrated inFIG. 1, the contact device2includes a first arc extinguishing member51, a second arc extinguishing member52, a first support member71and a second support member72. The first arc extinguishing member51and the second arc extinguishing member52are disposed in the first storage portion S1. The first and second arc extinguishing members51and52are made from a material that discharges an arc extinguishing gas by utilizing heat of an arc. The arc extinguishing gas is, for example, a gas containing hydrogen or nitrogen as a main component, and can extinguish an arc. Alternatively, the arc extinguishing gas is not limited to the gas mainly containing hydrogen or nitrogen, and may be a gas containing another element as a main component.

The first and second arc extinguishing members51and52may be formed of a material such as a phenol resin, a hydrogen storage metal, or a titanium hydride. Alternatively, the first and second arc extinguishing members51and52may be formed of, for example, a thermosetting resin such as an unsaturated polyester resin or a melamine resin. Alternatively, the first and second arc extinguishing members51and52may be formed of a thermoplastic resin such as a polyolefin resin, a polyamide resin, or a polyacetal resin. Alternatively, the first and second arc extinguishing members51and52may be formed of another material.

The first arc extinguishing member51is disposed facing a gap G1(hereinafter referred to as a “first gap G1”) between the first fixed contact14and the first movable contact16when the movable contacts16and17are in the open positions. The first arc extinguishing member51has a shape that tapers toward the first gap G1. The second arc extinguishing member52faces a gap G2(hereinafter referred to as a “second gap G2”) between the second fixed contact15and the second movable contact17when the movable contacts16and17are in the open positions. The second arc extinguishing member52has a shape that tapers toward the second gap G2.

The first arc extinguishing members51is connected to the first side surface42via the first support member71. The second arc extinguishing member52is connected to the second side surface43via the second support member72. The first arc extinguishing member51protrudes from the first side surface42toward the first gap G1. The second arc extinguishing member52protrudes from the second side surface43toward the second gap G2.

The first support member71supports the first arc extinguishing member51such that the first arc extinguishing member51is movable. The first support member71is connected to the first housing3aand the first arc extinguishing member51. Specifically, the first support member71is connected to the first side surface42and the first arc extinguishing members51. The second support member72supports the second arc extinguishing member52such that the second arc extinguishing member52is movable. The second support member72is connected to the first housing3aand the second arc extinguishing members52. Specifically, the second support member72is connected to the second side surface43and the second arc extinguishing members52. The first support member71is a coil spring and has a spring characteristic. The second support member72is a coil spring and has a spring characteristic.

The first support member71supports the first arc extinguishing member51such that a tip of the first arc extinguishing member51moves to separate from the first fixed contact14at least in the upper and lower direction. The first support member71supports the first arc extinguishing member51such that the tip of the first arc extinguishing member51move to separate from the first movable contact16at least in the upper and lower direction. The second support member72supports the second arc extinguishing member52such that a tip of the second arc extinguishing member52move to separate from the second fixed contact15at least in the upper and lower direction. The second support member72supports the second arc extinguishing member52such that the tip of the second arc extinguishing member52move to separate from the second movable contact17at least in the upper and lower direction.

Specifically, the first support member71supports the first arc extinguishing member51such that the tip of the first arc extinguishing member51is movable in the upper and lower direction. The first support member71supports the first arc extinguishing member51such that the tip of the first arc extinguishing member51is movable in the left-right direction. The first support member71supports the first arc extinguishing member51such that the tip of the first arc extinguishing member51is movable in the front-back direction.

The second support member72supports the second arc extinguishing member52such that the tip of the second arc extinguishing member52is movable in the upper and lower direction. The second support member72supports the second arc extinguishing member52such that the tip of the second arc extinguishing member52is movable in the left-right direction. The second support member72supports the second arc extinguishing member52such that the tip of the second arc extinguishing member52is movable in the front-back direction. However, a movable direction of the first arc extinguishing member51and the second arc extinguishing member52is not limited to the above-described direction and may be changed.

FIG. 3is an enlarged view illustrating the first arc extinguishing member51, the first support member71and its surroundings.FIG. 4is a perspective view of the first arc extinguishing member51. As illustrated inFIGS. 3 and 4, the first arc extinguishing member51has a trapezoidal shape. Specifically, the first arc extinguishing member51includes a tip portion61, a base portion62, and a tapered portion63. The tip portion61faces the first gap G1. The tip portion61has a flat shape. However, the tip portion61may have a curved shape. The tapered portion63is provided between the tip portion61and the base portion62. The tapered portion63has a shape that tapers from the base portion62toward the tip portion61.

The base portion62has a larger outer shape than the tip portion61. Specifically, the base portion62has a larger area than the tip portion61when viewed from a direction in which the first arc extinguishing member51faces the first gap G1. In other words, the tip portion61has a smaller area than the base portion62when viewed from the direction in which the first arc extinguishing member51faces the first gap G1. The dimension of the base portion62in the upper and lower direction is larger than the dimension of the tip portion61in the upper and lower direction. In other words, the dimension of the tip portion61in the upper and lower direction is smaller than the dimension of the base portion62in the upper and lower direction.

The first arc extinguishing member51is disposed proximate to the first gap G1. Specifically, in a direction from the first arc extinguishing member51toward the first gap G1, a distance D1between a tip of the first arc extinguishing member51and the first fixed contact14is smaller than a distance D2from the first housing3a(the first side surface42) to the tip of the first arc extinguishing member51. In the direction from the first arc extinguishing member51toward the first gap G1, a distance D3between the tip of the first arc extinguishing member51and the first movable contact16is smaller than the distance D2from the first housing3a(the first side surface42) to the tip of the first arc extinguishing member51.

The tapered portion63includes a first tapered surface64and a second tapered surface65. The first tapered surface64and the second tapered surface65are inclined such that a distance between the first tapered surface64and the second tapered surface65decreases toward the first gap G1. The first tapered surface64faces the first fixed contact14. The second tapered surface65faces of the first movable contact16. At least a part of the tip portion61is positioned between a lower end of the first fixed contact14and an upper end of the first movable contact16.

FIG. 5is a view illustrating the first fixed contact14, the first movable contact16, and the first arc extinguishing member51when viewed from the left-right direction. In other words,FIG. 5is the view illustrating the first fixed contact14, the first movable contact16, and the first arc extinguishing member51when viewed from the direction in which the first arc extinguishing member51faces the first gap G1. As illustrated inFIG. 5, the first tapered surface64overlaps the first fixed contact14when viewed from the direction in which the first arc extinguishing member51faces the first gap G1. The second tapered surface65overlaps the first movable contact16when viewed from the direction in which the first arc extinguishing member51faces the first gap G1.

The second arc extinguishing member52has a same structure as that of the first arc extinguishing member51except that the second arc extinguishing member52is provided substantially left-right symmetrically with respect to the first arc extinguishing member51. Therefore, detailed description of the second arc extinguishing member52is omitted.

In the contact device2according to the present embodiment described above, the first arc extinguishing member51is movably supported by the first support member71. Therefore, when the arc extinguishing gas is generated, the arc extinguishing gas causes an increase in pressure, whereby the first arc extinguishing member51moves. Thus, even if the first arc extinguishing member51is disposed proximate to the first gap G1, a large space can be secured between the first fixed contact14and the first arc extinguishing member51. Alternatively, a large space can be secured between the first movable contact16and the first arc extinguishing member51. Accordingly, an arc extinguishing gas can be generated proximate to the first gap G1and an arc can easily pass through a space between the first fixed contact14and the first arc extinguishing member51or a space between the first movable contact16and the first arc extinguishing member51. As a result, the arc is easily extended and quickly extinguished. Therefore, the arc extinguishing performance can be improved.

When the arc extinguishing gas is generated, pressure is instantly increased. This causes the first support member71to deform elastically, whereby the first arc extinguishing member51moves. However, after the instant pressure increase is finished, the elastic deformation of the first support member71is released and the first arc extinguishing member51returns to an original position.

The first arc extinguishing member51has a shape that tapers toward the first gap G1. Therefore, even if the arc extinguishing member51is disposed proximate to the first gap G1, a large space can be secured between the first fixed contact14and the first arc extinguishing member51. Alternatively, a large space can be secured between the first movable contact16and the first arc extinguishing member51. Thus, the arc extinguishing performance owing to the arc extinguishing gas can be further improved. The second arc extinguishing member52and the second support member72achieve the same effect as that of the first arc extinguishing member51and the first support member71as described above.

Although an embodiment of the present invention has been described so far, the present invention is not limited to the above embodiment and various modifications may be made within the scope of the invention. For example, the contact device may be used for a breaker, a switch, or the like, instead of a relay.

In the above embodiment, the drive device4pushes out the drive shaft19from the drive device4side so that the movable contact piece13moves toward the contact direction Z1. Also, the drive device4pulls in the drive shaft19toward the drive device4side so that the movable contact piece13moves toward the separation direction Z2. However, the operation direction of the drive shaft19for opening and closing the contacts may be opposite to that in the above embodiment. That is, the drive device4may pull in the drive shaft19toward the drive device4side so that the movable contact piece13moves toward the contact direction Z1. The drive device4may push out the drive shaft19from the drive device4side so that the movable contact piece13moves toward the separation direction Z2. That is, the contact direction Z1and the separation direction Z2may be opposite to those in the above embodiment.

The relay1adescribed above is a so-called plunger relay, but the present invention may be applied to another type of relay, instead of the plunger relay. For example, as illustrated inFIG. 6, the present invention may be applied to a hinged relay1b. InFIG. 6, the same reference numerals are given to the elements corresponding to those of the above-described embodiment. With the hinged relay1billustrated inFIG. 6, when the coil32is magnetized, an armature36is attracted to an iron core39by magnetic force of the coil32, causing the armature36to swing. A card37is connected to the armature36. The card37presses the movable contact piece13in response to the swing of the armature36, causing the movable contact piece13and the movable contact16to move toward the contact direction Z1. As a result, the movable contact16contacts the fixed contact14.

When the coil32is demagnetized, the armature36swings toward the opposite direction by elastic force of a hinge spring38. As a result, the card37, the movable contact piece13, and the movable contact16move toward the separation direction Z2, and the movable contact16separates from the fixed contact14. The arc extinguishing member51is disposed facing the gap G1between the movable contact16and the fixed contact14. The arc extinguishing member51has a shape that tapers toward the gap G1. The arc extinguishing member51is supported by the support portion71such that the arc extinguishing member51is movable. Accordingly, the hinged relay1balso achieves the same effect as that of the relay1aaccording to the above-described embodiment.

The shape or disposition of the first fixed terminal11, the second fixed terminal12, or the movable contact piece13may be changed. The shape or disposition of the coil32, the spool30, or the yoke34may be changed. The shape or disposition of the first fixed contact14, the second fixed contact15, the first movable contact16, and the second movable contact17may be changed.

The first fixed contact14may be provided separately from or integrated with the first fixed terminal11. The second fixed contact15may be provided separately from or integrated with the second fixed terminal12. The first movable contact16may be provided separately from or integrated with the movable contact piece13. The second movable contact17may be provided separately from or integrated with the movable contact piece13.

The shape and/or disposition of the arc extinguishing member is not limited to that of the above-described embodiment and may be changed. For example, the arc extinguishing member may be connected to the top surface41via the support member, instead of the side surfaces42and43of the housing3. Alternatively, the arc extinguishing member may be connected to the partition wall46via the support member.

In the above-described embodiment, the first arc extinguishing member51faces the first gap G1in the left-right direction. The second arc extinguishing member52faces the second gap G2in the left-right direction. However, the direction in which the arc extinguishing member and the gap face each other is not limited to the left-right direction, that is, not limited to the longitudinal direction of the movable contact piece13. For example,FIG. 7is a plan view of the contact device2according to a first modified example. As illustrated inFIG. 7, the arc extinguishing members51and52may face the gaps G1and G2in the front-back direction. That is, the arc extinguishing members51and52may face the gaps G1and G2in the lateral direction of the movable contact piece13.

In the above-described embodiment, the first arc extinguishing member51and the second arc extinguishing member52are provided. However, the number of arc extinguishing members is not limited to two and may be less than two or more than two. For example, one of the first arc extinguishing member51or the second arc extinguishing member52may be omitted. Alternatively,FIG. 8is a plan view of the contact device2according to a second modified example.FIG. 9is a cross-sectional view taken along a line XI-XI ofFIG. 8. As illustrated inFIGS. 8 and 9, two arc extinguishing members51and53may be disposed facing the first gap G1, with the first gap G1in between. The arc extinguishing members51and53may be supported by the first housing3avia the support members71and73, respectively. Two arc extinguishing members52and54may be disposed facing the second gap G2, with the second gap G2in between. The arc extinguishing members52and54may be supported by the first housing3avia the support members72and74, respectively.

The arc extinguishing member may have another shape, instead of a trapezoidal shape. For example, the arc extinguishing member may have a pyramid shape, a truncated pyramid shape, a cone shape, or a truncated cone shape. Alternatively, as illustrated inFIG. 10, the first arc extinguishing member may have a shape different from the shape that tapers. Likewise, the other arc extinguishing members as described above may have a shape different from the shape that tapers.

The support member may have another shape, instead of a coil spring. For example, as illustrated inFIG. 11, the first support member71may be a leaf spring. Likewise, the support members as described above may be a leaf spring. Alternatively, the support member may have another structure other than a spring as long as the support member supports the arc extinguishing member such that the arc extinguishing member is movable.

The first arc extinguishing member51may be movably provided without using the support member. For example, as illustrated inFIG. 12, the first arc extinguishing member51may include a part66that has a spring characteristic. The first arc extinguishing member51may be movably provided by the part66that has the spring characteristic. Likewise, the other arc extinguishing members as described above may be movably provided without using the support member.

REFERENCE NUMERALS