JP2008027585A - Vacuum switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum switch having a structure easy to mold, capable of preventing cracks caused by thermal stress produced in the bonded part of an insulated cylinder while achieving electric field relaxation in the inside of an insulating outer cover and the inside of the vacuum vessel at the same time. <P>SOLUTION: A vacuum vessel is composed of a shield plate joined to both ends of an insulated cylinder, and a stationary electrode side plate and a movable electrode side plate which are connected to the shied plate. Both tips of the shield plate are formed into curvature portions, the tip positioned in the direction of the inside of the vacuum vessel is formed into a plate bent so as to cover the joined portion of the insulated cylinder and the shield plate, and the tip positioned in the outside of the vacuum vessel is formed so as to be positioned outside of the outer peripheral wall of the insulated cylinder. Grooves are provided on the surface making contact with the outer peripheral wall and the inner peripheral wall of the insulated cylinder in the surface joining the shield plate to both ends of the insulated cylinder, and the groove of the insulated cylinder which is positioned in the direction of the outer peripheral side of the insulated cylinder is formed so as to be sealed by a metal such as invar formed in a ring shape. An insulating outer cover such as a resin cover having at least a prescribed thickness is provided in the outer periphery of the vacuum vessel. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vacuum switch in which a vacuum container is molded with an insulating material such as an epoxy resin.

  A general vacuum switch forms a vacuum container by hermetically sealing both ends of an insulating cylinder with a fixed electrode side plate and a movable electrode side plate. The fixed electrode lead is vacuum-tightly fixed to the fixed electrode side plate. The movable electrode lead is attached to the movable electrode side plate 4 via a bellows so that the fixed electrode and the movable electrode can be opened and closed while maintaining a vacuum.

  As a prior art of this type of vacuum switch, for example, there is one shown in Patent Document 1.

JP 2001-338557 A

  In a general vacuum switch, the effect of electric field relaxation can be expected by providing a metal bowl-shaped shield plate so as to cover the end of the bonded portion of the insulating cylinder. However, there is a possibility that cracks may occur due to differences in the linear expansion coefficient between the fixed electrode side plate, the movable electrode side plate, and both end faces of the insulating cylinder, and this crack may reduce the reliability of the product.

  Further, when the shape of the outer periphery of the vacuum vessel becomes complicated, there is a possibility that a gap is formed inside the resin layer during molding by the resin.

  An object of the present invention is to provide a vacuum switch that is easy to mold and can prevent cracking due to thermal stress or the like generated in the bonded portion of an insulating cylinder while simultaneously achieving electric field relaxation inside the insulating shell and inside the vacuum vessel. There is.

  The object is to provide a vacuum switch in which a fixed electrode lead and a movable electrode lead are arranged opposite to each other in a vacuum vessel including an insulating cylinder, and the fixed electrode and the movable electrode are respectively attached to the inner ends of the electrode leads. The container is composed of a side plate of the fixed electrode and a side plate of the movable electrode that connect the shield plate and the shield plate joined to both ends of the insulating tube in order to hermetically seal both ends of the insulating tube, and the shield plate Both ends are formed in a curvature portion, the tip located inside the vacuum vessel is formed on a plate bent so as to cover the junction between the insulating cylinder and the shield plate, and the tip located outside the vacuum vessel is insulated. It is formed so as to be located outside the outer peripheral wall of the cylinder, and a groove is provided on the surface that contacts the outer peripheral wall and inner peripheral wall of the insulating cylinder among the surfaces that join the shield plate and both end faces of the insulating cylinder. The above The groove of the shield plate located on the outer peripheral side of the edge tube is sealed with a metal formed in a ring shape, and the outer periphery of the vacuum vessel is provided with an insulating skin provided with at least a predetermined thickness Is achieved.

  Further, the object is that the both ends of the shield plate have a curved portion, and the tip located inside the vacuum vessel is formed on a plate bent so as to cover the joint between the insulating tube and the shield plate, A tip located outside the vacuum vessel is positioned outside the outer peripheral wall of the insulating cylinder, and a groove is formed on the surface contacting the outer peripheral wall and inner peripheral wall of the insulating cylinder among the surfaces joining the shield plate and both ends of the insulating cylinder. And the groove of the shield plate positioned toward the outer peripheral side of the insulating cylinder and the groove of the shield plate positioned toward the inner peripheral side of the insulating cylinder are achieved by sealing with a ring-shaped metal. The

  Further, the object is that the width of the groove formed on the surface in contact with both ends of the insulating cylinder is formed from a position not less than the center of the thickness of the insulating cylinder to a position not more than the tip of the shield plate. The height of the groove is achieved by being 90% or less of the thickness of the shield plate.

  The above object is achieved by the shield plate being made of aluminum or copper.

  Further, the above object is achieved by the fact that the metal that seals the groove formed in the shield plate is made of invar.

  Further, the object is that the fixed electrode side plate and the movable electrode side plate are bent so that the direction of the shield plate covers the joint between the insulating tube and the shield plate, and the bent shield plate The tip is positioned toward the inside of the vacuum vessel, and the shield is bonded with a silver paste to the surface on the side without a groove sealed with a ring-shaped metal formed on the shield, and fixed with an adhesive. The surface on the side where there is a groove sealed with a ring-shaped metal formed on the plate is positioned so that the groove of the shield plate is in contact with the inner and outer peripheral walls of both ends of the insulating cylinder, and the insulating This is achieved by adhering to both ends of the cylinder with silver paste and fixing with an adhesive.

  According to the present invention, there is provided a vacuum switch that can prevent cracking due to thermal stress or the like generated in the bonded portion of the insulating cylinder 2 while simultaneously achieving electric field relaxation inside the insulating shell and inside the vacuum vessel, and is easy to mold. it can.

First, a general vacuum switch will be described with reference to FIGS.
FIG. 6 is a sectional view of a general vacuum switch.
FIG. 7 is a cross-sectional view of a general resin mold vacuum switch that is resin molded with an insulating outer shell.
FIG. 8 is a cross-sectional view of a general resin mold vacuum switch in which a fixed electrode lead is exposed on the outer periphery of the vacuum switch and an epoxy resin is molded.
In FIG. 6, the vacuum switch 1 forms a vacuum vessel 5 by hermetically sealing the opening portions at both ends of the insulating cylinder 2 with the fixed electrode side plate 3 and the movable electrode side plate 4. The fixed electrode lead 6 is fixed to the fixed electrode side plate 3 in a vacuum-tight manner. The movable electrode lead 7 is attached to the movable electrode side plate 4 via a bellows 8, and is configured to open and close the fixed electrode 6a and the movable electrode 7a while maintaining a vacuum.

The vacuum switch 1 having such a configuration immediately extinguishes an arc generated when a contact is opened and closed in a high vacuum using a high vacuum having an excellent dielectric strength against high voltage in the insulating cylinder 2. To shut off the high voltage circuit. Thus, since the vacuum switch 1 opens and closes the fixed electrode 6a and the movable electrode 7a in a high vacuum, it is possible to cut off the high voltage circuit by shortening the distance between the electrodes necessary for interruption. Therefore, there exists an advantage that the insulating cylinder 2 which accommodates the electrode of a vacuum switch can be made compact.

  However, the fact that the insulating cylinder 2 can be made compact means that the creeping insulation distance outside the insulating cylinder 2 is shortened, and when dirt in the atmosphere adheres to the insulating cylinder 2, the withstand voltage is lowered and an external short circuit is caused. It tends to occur. As a countermeasure against this, conventionally, it has been proposed to provide an insulating shell such as an epoxy resin on the outer periphery of the vacuum vessel 5.

  In FIG. 7, an insulating skin 9 such as an epoxy resin is provided outside the vacuum vessel 5.

  This type of vacuum switch 1 is formed in such a manner that a vacuum vessel 5 is formed by hermetically sealing both end openings of an insulating cylinder 2 with a fixed electrode side plate 3 and a movable electrode side plate 4. The side plate 4 and the insulating cylinder 2 are fixed with a silver paste and further fixed with an adhesive. Electric field concentration occurred at both ends of the bonded portion inside the vacuum vessel 5 and the insulating outer shell 9, which was a problem. In order to prevent such electric field concentration, a metal shield plate is provided in the insulating sheath 9.

  In FIG. 8, an insulating skin 9 in which the fixed electrode lead 6 is exposed and an epoxy resin is molded is provided on the outer periphery of the vacuum switch 1. The insulating skin 9 is insulated from the fixed electrode side plate 3 and the movable electrode side plate 4. In order to fix the cylinder 2, a metal bowl-shaped shield plate 10 is provided so as to cover the end of the bonded portion of the insulating cylinder 2.

  However, this type of vacuum switch, as described above, may cause cracks due to the difference in linear expansion coefficient between the fixed electrode side plate, the movable electrode side plate and the both ends of the insulating cylinder. May be reduced.

  Therefore, the present invention will be described as a result of various investigations on the structure in which cracks do not occur.

A vacuum switch according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a sectional view of a vacuum switch provided with an embodiment of the present invention.
2 to 4 are views showing a shield structure provided with an embodiment of the present invention.
In FIG. 1, a fixed electrode lead 6 and a movable electrode lead 7 are arranged to face each other in a vacuum vessel 5 configured to include a substantially cylindrical insulating tube 2 made of an insulating material such as ceramic. A fixed electrode 6a and a movable electrode 7a are attached to the inner ends, respectively. The fixed electrode 6a and the movable electrode 7a are made of a good conductor such as copper. The fixed electrode lead 6 has a substantially rod shape with a flange portion 6b formed in the middle portion, penetrates through the fixed electrode side plate 3, and is fixed to the fixed electrode side plate 3 at one side main surface of the flange portion 6b.

  On the other hand, the movable electrode lead 7 has a substantially rod shape, is disposed through the hole of the movable electrode side plate 4, and is connected to the movable electrode side plate 4 by a bellows 8 as an expansion / contraction means provided between the movable electrode side plate 4. Has been. The movable electrode 7a can be brought into and out of contact with the fixed electrode 6a by a moving means (not shown).

  The vacuum vessel 5 includes a fixed electrode side plate 3 and a movable electrode side plate 4 having a shield plate 10 made of stainless steel or the like in order to hermetically seal both ends of the insulating cylinder 2. A hole is formed in the central portion of the fixed electrode side plate 3 and the movable electrode side plate 4, and the fixed electrode lead 6 and the movable electrode lead 7 are passed through the hole.

  In FIG. 2, the shape of the shield plate 10 is provided with curvature portions at both ends 10a and 10b. In order to provide a curvature part, the shield board 10 of considerable thickness (4 mm in the example of a form of a present Example) is required. The tip 10a inside the vacuum vessel is formed on a plate bent so as to cover the bonding portion between the insulating cylinder 2 and the shield plate 10, and the tip 10b outside the vacuum vessel 5 is outside the outer peripheral wall of the insulating cylinder. It is formed to be located.

  Thus, by providing the shield plate 10 with a curved portion and forming it on a plate bent so as to cover the adhesive portion, electric field relaxation inside and outside the vacuum vessel 5 is expected. A groove 10c is provided on the surface of the shield plate 10 in contact with the outer peripheral wall and the inner peripheral wall of the insulating tube 2.

  Further, as shown in FIG. 3, the groove 10d of the shield plate in contact with the outer peripheral wall of the insulating cylinder 2 is formed so as to be sealed with a metal ring 11 (invar in this embodiment).

  Further, as shown in FIG. 4, the shield plate groove 10c in contact with the inner peripheral wall of the insulating cylinder 2 may be formed so as to be sealed with a metal ring 11 (invar in this embodiment).

  FIG. 5 shows a form in which the grooves 10c and 10d of the shield plate are provided large and the metal ring 11 is fitted. The width 12 of the groove formed on the surface of the shield plate in contact with both ends of the insulating cylinder is formed from a position above the center of the thickness of the insulating cylinder 2 to a position below the tip of the shield board 10. The height 13 is 90% or less of the thickness of the shield plate.

As a result, it is possible to prevent cracks due to thermal stress or the like generated at the bonded portion of the insulating cylinder 2. The linear expansion coefficient of the shield plate 10 made of stainless steel and the like, 16.0 × 10 ⁻⁶ (kg / mm ³ ), and the linear expansion of the insulating cylinder 2 made of alumina bonded and fixed to the shield plate 10 The coefficient is 7.5 × 10 ⁻⁶ (kg / mm ³ ), which is a thermophysical value less than half. In the molding process in which heat is applied, thermal stress is generated at the end of the adhesive interface due to expansion or contraction due to such a difference in thermophysical values.

Therefore, in the present embodiment described above, the thermal expansion is prevented and the linear expansion coefficient is 1.50 × 10 ⁻⁶ (kg / mm ³ ) by reducing the joint area of the members made of materials having different linear expansion coefficients. By fitting a small invar into the shield plate 10, the thermal stress due to the difference in linear expansion coefficient between the insulating cylinder 2 and the shield plate is reduced. Moreover, since a reduction in thermal stress can be expected in this way, it is possible to form a plate thickness that can provide a large curvature at the tip of the shield plate.

  In addition, each of the fixed electrode side plate 3 and the movable electrode side plate 4 has the shield plate tip 10a bent in such a way as to cover the joint between the insulating tube 2 and the shield plate 10 in the direction of the shield plate 10 inside the vacuum vessel 5. Adhered to the surface of the shield plate that is sealed with the ring-shaped metal formed on the shield plate 10 on the side of the shield plate 10 that is not grooved 10c, 10d with silver paste, and then fixed with an adhesive The surface of the shield plate that is sealed with the ring-shaped metal formed on the shield plate 10 on the side where the grooves 10c and 10d are present is the grooves 10c and 10d of the shield plate 10 inside the both ends of the insulating cylinder 2. It is positioned so as to be in contact with the peripheral wall and the outer peripheral wall, and is bonded to both ends of the insulating cylinder 2 with silver paste and further fixed with an adhesive.

  The outer periphery of the vacuum vessel 5 is formed with an insulating skin 9 made of resin or the like provided with a predetermined thickness. At this time, it is difficult to use a complicated shape such as a large unevenness as the outer peripheral shape of the vacuum vessel 5 so that there is no gap inside the insulating skin 9. However, as shown in FIG. 8 of the prior art, in order to alleviate the electric field inside the insulating skin 9, it is necessary to use a shield-like shield plate 10 to prevent electric field concentration. There was a risk of occurrence.

  The shield plate 10 of the present embodiment is expected to provide electric field relaxation without providing a large curvature portion at the tip 10b of the shield plate 10 and providing a complicated structure such as bending by being positioned inside the insulating shell 9 from the outer peripheral wall of the insulating cylinder 2. it can. Therefore, the structure of the shield plate 10 of this embodiment for relaxing the electric field is less likely to cause a gap when the insulating skin 9 is provided. However, in order to increase the curvature portion, the shield plate is thick. However, as described above, the shield plate is provided with grooves 10c and 10d so as to reduce the thermal stress due to different linear expansion coefficients, and the groove 10c. , 10d is devised such as a structure sealed with a metal ring 11 such as Invar.

It is a vacuum switch which shows the state which attached the shield board explaining the vacuum switch of Embodiment 1 of this invention. It is a figure explaining the shape of the shield board used for the vacuum switch of Embodiment 1. FIG. It is a figure explaining the shape by which the metal ring is engage | inserted by the groove | channel outside the vacuum vessel of the shield board used for the vacuum switch of Embodiment 1. FIG. It is a figure explaining the shape by which the metal ring is engage | inserted in the groove | channel outside the vacuum vessel of a shield board used for the vacuum switch of Embodiment 1, and a vacuum vessel inside. It is a figure explaining the magnitude | size of the groove | channel outside the vacuum vessel of a shield board used for the vacuum switch of Embodiment 1, and a vacuum vessel inside. It is a figure which shows the structure of the conventional typical vacuum switch. It is a figure which shows the structure of the conventional resin mold vacuum switch resin-molded with the insulation outer shell. It is sectional drawing of the general resin mold vacuum switch which exposed the fixed electrode lead to the outer periphery of a vacuum switch, and molded the epoxy resin.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vacuum switch, 2 ... Insulating cylinder, 3 ... Fixed electrode side plate, 4 ... Movable electrode side plate, 5 ... Vacuum container, 6 ... Fixed electrode lead, 6a ... Fixed electrode, 7 ... Movable electrode lead, 7a ... Movable electrode, 8 ... Bellows, 9 ... Insulating skin, 10 ... Shield plate, 10a, 10b ... Tip of shield plate, 10c, 10d ... Shield plate groove, 11 ... Metal ring, 12 ... Groove width, 13 ... Groove height.

Claims (6)

In a vacuum switch in which a fixed electrode lead and a movable electrode lead are arranged opposite to each other in a vacuum vessel including an insulating cylinder, and a fixed electrode and a movable electrode are attached to the inner ends of the respective electrode leads,
The vacuum vessel is composed of a side plate of the fixed electrode and a side plate of the movable electrode that connect the shield plate and the shield plate joined to both ends of the insulating tube in order to hermetically seal both ends of the insulating tube, Both ends of the shield plate are formed in a curved portion, and the tip located inside the vacuum vessel is formed in a plate bent so as to cover the junction between the insulating cylinder and the shield plate, and the tip located outside the vacuum vessel Is formed to be located outside the outer peripheral wall of the insulating cylinder,
A groove is provided in a surface contacting the outer peripheral wall and the inner peripheral wall of the insulating cylinder among the surfaces joining the shield plate and both end faces of the insulating cylinder, and the shield plate located on the outer peripheral side of the insulating cylinder A vacuum switch characterized in that the groove is sealed with a ring-shaped metal, and an outer skin provided with at least a predetermined thickness is provided on the outer periphery of the vacuum vessel. The vacuum switch according to claim 1, wherein
Both ends of the shield plate have a curved portion, and the tip located inside the vacuum vessel is formed on a plate bent so as to cover the junction between the insulating tube and the shield plate, and is outside the vacuum vessel. The tip located is located outside the outer peripheral wall of the insulating cylinder, and has a groove on the surface contacting the outer peripheral wall and inner peripheral wall of the insulating cylinder among the surfaces joining the shield plate and both ends of the insulating cylinder. The vacuum switch according to claim 1, wherein the groove of the shield plate positioned toward the outer peripheral side of the tube and the groove of the shield plate positioned toward the inner peripheral side of the insulating tube are sealed with a ring-shaped metal. The vacuum switch according to claim 1, wherein
The width of the groove formed on the surface in contact with both ends of the insulating cylinder is formed from the position above the center of the thickness of the insulating cylinder to the position below the tip of the shield plate, and the height of the groove of the shield plate is A vacuum switch characterized by being 90% or less of the thickness of the shield plate. The vacuum switch according to claim 1, wherein
The vacuum switch, wherein the shield plate is made of aluminum or copper. The vacuum switch according to claim 1, wherein
The vacuum switch according to claim 1, wherein the metal for sealing the groove formed in the shield plate is formed of invar. The vacuum switch according to claim 1, wherein
Each of the fixed electrode side plate and the movable electrode side plate is bent so that the direction of the shield plate covers the joint between the insulating tube and the shield plate, and the tip of the bent shield plate is connected to the vacuum vessel. It is located on the inside, and is bonded to the surface on the side where there is no groove sealed with a ring-shaped metal formed on the shield and fixed with an adhesive, and formed on the shield plate The surface on the side where there is a groove sealed with a ring-shaped metal is positioned so that the groove of the shield plate is in contact with the inner peripheral wall and the outer peripheral wall of both ends of the insulating cylinder, and on both ends of the insulating cylinder A vacuum switch that is bonded with silver paste and fixed with an adhesive.

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