Patent Grant
10854403
The present invention relates to a vacuum interrupter used for a vacuum circuit breaker or the like.
In general, a vacuum interrupter has a structure in which electrodes for performing conduction and interruption of current are provided so as to be opposed to each other in a vacuum container composed of two insulation containers. The two insulation containers composing the vacuum container are made from an insulation material such as a glass material or a ceramic material. A fixed-side end plate is attached to an end of one of the insulation containers, a movable-side end plate is attached to an end of the other insulation container, and both insulation containers are joined with their openings opposed to each other, to form the vacuum container. A fixed-side electrode rod penetrates through the fixed-side end plate and is fixed thereto, and a movable-side electrode rod penetrates through the movable-side end plate and is fixed thereto. A fixed-side electrode and a movable-side electrode are attached to respective ends of the fixed-side electrode rod and the movable-side electrode rod so as to be opposed to each other.
A bellows formed by processing a thin metal plate such as stainless steel in a bellows shape is attached around the movable-side electrode rod. One end of the bellows is joined to the movable-side end plate and the other end is joined to the movable-side electrode rod. The part where the bellows and the movable-side electrode rod are joined to each other is covered with a bellows cover. Providing the bellows and the bellows cover enables the inside of the vacuum container to be maintained in an airtight state even under operation of the movable-side electrode rod.
An arc shield is provided around the movable-side electrode and the fixed-side electrode in the vacuum container, and a contamination preventing portion of the arc shield surrounds the electrodes, thereby preventing the inner surface of the vacuum container from being contaminated due to occurrence of an arc when the electrodes are opened or closed. The vacuum container forming the vacuum interrupter is formed such that the two insulation containers on the fixed side and the movable side are joined to each other with their openings opposed to each other as described above, and a part of the arc shield is held between the joined parts so as to be fixed.
Patent Document 1: Japanese Laid-Open Patent Publication No. 58-169833
Patent Document 2: Japanese Laid-Open Patent Publication No. 58-204432
Patent Document 3: Japanese Laid-Open Patent Publication No. 2003-317583
In order to ensure stable interruption performance and withstand voltage performance of the vacuum interrupter, it is necessary to prevent positional deviation of the contamination preventing portion of the arc shield provided around the electrodes in the vacuum container. When positional deviation of the arc shield occurs and the contamination preventing portion of the arc shield becomes eccentric from the axis of the vacuum interrupter, the electric field value increases at a part where the spatial distance between the contamination preventing portion of the arc shield, and the movable-side electrode and the fixed-side electrode, is shortened. Thus, interruption performance and withstand voltage performance are locally reduced. In a general vacuum interrupter, openings of two insulation containers are opposed to each other so as to hold an arc shield therebetween, thereby fixing the arc shield. At this time, it is necessary to use a jig for arranging them at accurate positions, and thus the working time is prolonged and the process is complicated. Meanwhile, for the purpose of simplification, in the case of performing positioning through visual observation without using a jig or the like, withstand voltage performance might become insufficient.
Reduction in withstand voltage performance can be caused due to minute protrusions on the surfaces of the movable-side electrode, the fixed-side electrode, and the arc shield. After the vacuum container and the like are brazed, in order to remove the minute projections, voltage may be applied to the movable-side electrode or the fixed-side electrode, thereby performing minute projection removal called voltage conditioning. However, in some cases, the arc shield is grounded during voltage conditioning. Therefore, in the case where a flange portion of the arc shield protruding from the insulation container has a narrow width, a complicated jig is needed for connecting a grounding wire, thus causing a problem of prolonging the working time.
The present invention has been made to solve the above problem, and an object of the present invention is to obtain a vacuum interrupter that facilitates positioning of an arc shield provided inside the vacuum interrupter and achieves simplification of an assembly process and shortening of the working time.
Another object of the present invention is to obtain a vacuum interrupter that facilitates connection of a grounding wire to an arc shield in voltage conditioning for removing minute projections of electrodes and the like, thereby shortening a time required for the voltage conditioning.
A vacuum interrupter according to the present invention includes: a vacuum container formed by two insulation containers each having an opening at one end thereof, the openings being opposed to each other; a pair of electrodes provided inside the vacuum container; and an arc shield having a contamination preventing portion surrounding the electrodes, and projections projecting in a direction along an outer circumferential surface of the contamination preventing portion, the arc shield being positioned by the projections being engaged with the openings.
In the vacuum interrupter according to the present invention, the projections formed at the flange portion of the arc shield are engaged with the openings of the insulation containers, so as to position the arc shield, whereby the arc shield and the vacuum container composed of the two insulation containers can be accurately arranged and combined. Therefore, the contamination preventing portion of the arc shield can be prevented from becoming eccentric from the axis of the vacuum interrupter, whereby interruption performance and withstand voltage performance can be stabilized. In addition, since the arc shield itself has a positioning function, an assembly jig is not needed and thus the working time is shortened. Further, since the protrusion pieces of the flange portion of the arc shield protrude from the outer circumferential surface of the insulation container, it is possible to easily connect a grounding wire to the arc shield by a clip or the like at the time of voltage conditioning for removing minute projections of the electrodes and the like. Therefore, a jig for connecting the grounding wire is not needed and the working time can be shortened.
In description of embodiments and the drawings, the same or corresponding parts are denoted by the same reference characters.
Embodiment 1
With reference to
As shown in
A fixed-side electrode 5 and a movable-side electrode 3 are respectively attached to the fixed-side electrode rod 8 and the movable-side electrode rod 7 so as to be opposed to each other. A bellows 11 and a bellows cover 12 are attached to the movable-side electrode rod 7, and maintain the inside of the vacuum container 2 in an airtight state while operating correspondingly to movement of the movable-side electrode rod 7 during open/close operation of the electrodes.
As shown in
The contamination preventing portion 10a of the arc shield 10 is provided so as to surround the contact parts of the electrodes, thereby suppressing contamination of the surroundings due to an arc occurring at the time of interruption operation of the movable-side electrode 3 and the fixed-side electrode 5.
As shown in the sectional view of the vacuum interrupter 1 in
The state in which the arc shield 10 is fixed by being held between the openings of the insulation containers 9 is shown in the enlarged sectional view in
When the arc shield 10 is mounted such that the embossed-shape projections 10c formed on the protrusion pieces 10d of the arc shield 10 are engaged with the openings of the insulation containers 9, the contamination preventing portion 10a of the arc shield 10 is located concentrically with the wall surface of the vacuum container 2, and thus the contamination preventing portion 10a can be prevented from becoming eccentric from the axis of the vacuum interrupter 1. As a result, there is no part where the distance between the contamination preventing portion 10a of the arc shield 10, and the movable-side electrode 3 and the fixed-side electrode 5, is shortened, and thus interruption performance and withstand voltage performance are stabilized.
Regarding positioning between the arc shield 10 and the insulation containers 9, the embossed-shape projections 10c formed on the protrusion pieces 10d of the arc shield 10 have a positioning function. Therefore, an assembly jig for positioning is not needed and the working time can be shortened. Further, since such unnecessary members are not used, the number of components can be decreased.
In the case where the protrusion pieces 10d still protrude outward from the outer circumferential surfaces of the insulation containers 9 in a state in which the arc shield 10 is fixed in the vacuum container 2, voltage conditioning for removing minute projections on the surfaces of the electrodes and the arc shield 10 is performed after the assembly process is completed by brazing of the vacuum interrupter 1. At this time, a grounding wire can be easily connected to the protrusion piece 10d by a clip or the like. Therefore, a specific jig or the like is not needed for connection of the grounding wire and the working time can be shortened.
After voltage conditioning, the vacuum interrupter 1 can be used in a state in which the protrusion pieces 10d are left as they are. However, leaving the protrusion pieces 10d might form an electric field vulnerable part which leads to insufficiency of withstand voltage performance, or when the vacuum interrupter 1 is incorporated into the vacuum circuit breaker, the left protrusion pieces 10d might interfere with peripheral equipment. If such a problem arises, the protrusion pieces 10d may be removed. In the case of removing the protrusion pieces 10d formed on the flange portion 10b, the plate thickness of the entire protrusion pieces 10d or cutting portions of the protrusion pieces 10d may be set to about 1 to 2 mm, so that they can be removed by being cut using a nipper or the like.
The contamination preventing portion 10a of the arc shield 10 has a cylindrical shape and is provided so as to surround the outer circumferences of the fixed-side electrode 5 and the movable-side electrode 3. Therefore, projections formed by cutting the protrusion pieces 10d present outside the contamination preventing portion 10a have very little influence on the electric field intensity inside the contamination preventing portion 10a, and thus it is considered that, basically, a specific process for relaxing the electric field is not needed. However, for example, in the case of interrupting very high voltage or in the case of providing a grounding part near the parts where the protrusion pieces 10d are cut, withstand voltage performance might become unsatisfactory due to minute projections formed on the edges of the parts where the protrusion pieces 10d are cut. In such a case, the parts where the protrusion pieces are cut and the edges thereof may be polished so as to remove such projections and smooth the surfaces thereof, whereby reduction in withstand voltage performance can be prevented. In addition, an electric field relaxing part (e.g., corona ring) made of metal or conductive resin may be attached on the outer circumferential side of the flange portion 10b of the arc shield 10 so as to cover the parts where the protrusion pieces are cut. Even in this case, reduction in withstand voltage performance can be prevented similarly.
In the present embodiment, the protrusion pieces 10d are formed around the flange portion 10b of the arc shield 10, the embossed-shape projections 10c are formed on the protrusion pieces 10d, and the embossed-shape projections 10c are engaged with the openings of the insulation containers 9, thereby positioning the arc shield 10. However, it is possible to obtain such a positioning effect similarly even in the case of forming embossed portions 10c directly on the flange portion 10b without using the protrusion pieces 10d.
Embodiment 2
With reference to
In comparison between the vacuum interrupter 1 described in embodiment 1 and the vacuum interrupter 1 of the present embodiment, in embodiment 1, the embossed-shape projections 10c are formed on the protrusion pieces 10d of the arc shield 10. On the other hand, the present embodiment is different in that the bent-shape projections 10e each formed by bending a part of the flange portion 10b in the axial direction of the vacuum container 2 are provided around the flange portion 10b of the arc shield 10. The flange portion 10b of the arc shield 10 having the bent-shape projections 10e is fixed by being held between the openings of the two insulation containers 9. Thus, owing to the positioning effect by the bent-shape projections 10e, it is possible to prevent the contamination preventing portion 10a of the arc shield 10 from becoming eccentric from the axis of the vacuum interrupter 1. As a result, the spatial distance between the contamination preventing portion 10a, and the movable-side electrode 3 and the fixed-side electrode 5, is not shortened, and interruption performance and withstand voltage performance can be stabilized.
In the present embodiment, the bent-shape projections 10e are formed directly on the flange portion 10b of the arc shield 10, and the bent-shape projections 10e are engaged with the openings of the insulation containers 9, thereby positioning the arc shield 10. However, it is possible to obtain such a positioning effect similarly even in the case of forming the protrusion pieces 10d around the flange portion 10b and forming the bent-shape projections 10e on the protrusion pieces 10d.
Embodiment 3
With reference to
As shown in the sectional view of the vacuum interrupter 1 in
The state in which the arc shield 10 is fixed by being held between the openings of the insulation containers 9 is shown in the enlarged sectional view in
When the arc shield 10 is mounted such that the embossed-shape projections 10c formed on the flange portion 10b of the arc shield 10 are engaged with the inner circumferential portions of the openings of the insulation containers 9, the contamination preventing portion 10a of the arc shield 10 is located concentrically with the wall surface of the vacuum container 2, and thus the contamination preventing portion 10a can be prevented from becoming eccentric from the axis of the vacuum interrupter 1. As a result, there is no part where the distance between the contamination preventing portion 10a of the arc shield 10, and the movable-side electrode 3 and the fixed-side electrode 5, is shortened, and thus interruption performance and withstand voltage performance are stabilized.
Regarding positioning between the arc shield 10 and the inner circumferential portions of the insulation containers 9, the embossed-shape projections 10c formed on the flange portion 10b of the arc shield 10 have a positioning function. Therefore, an assembly jig for positioning is not needed and the working time can be shortened. Further, since the positioning is performed at the inner circumferential portions of the insulation containers 9, there are no protrusions on the outer circumferential portions of the insulation containers 9. Therefore, as compared to the case of embodiment 1 or embodiment 2, the insulation strength on the outer circumferential portions of the insulation containers 9 can be improved.
1 vacuum interrupter
2 vacuum container
3 movable-side electrode
4 movable-side end plate
5 fixed-side electrode
6 fixed-side end plate
7 movable-side electrode rod
8 fixed-side electrode rod
9 insulation container
10 arc shield
10
a contamination preventing portion
10
b flange portion
10
c embossed-shape projection
10
d protrusion piece
10
e bent-shape projection
11 bellows
12 bellows cover
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-078040 | Apr 2017 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/038484 | 10/25/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2018/189939 | 10/18/2018 | WO | A |
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| 3048681 | Polinko, Jr. | Aug 1962 | A |
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| 6255615 | Kimblin | Jul 2001 | B1 |
| 20120168291 | Reuber | Jul 2012 | A1 |
| 20130120879 | Shea | May 2013 | A1 |
| 20160141119 | Li | May 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| 2341979 | Mar 2000 | GB |
| S58169833 | Oct 1983 | JP |
| S58204432 | Nov 1983 | JP |
| 2003317583 | Nov 2003 | JP |
| Entry |
|---|
| International Search Report (PCT/ISA/210) with translation, and Written Opinion (PCT/ISA/237) dated Dec. 26, 2017, by the Japan Patent Office as the International Searching Authority for International Application No. PCT/JP2017/038484. |
| Number | Date | Country | |
|---|---|---|---|
| 20200043686 A1 | Feb 2020 | US |
