JP2006079989A - Vacuum valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a vacuum valve with bellows turning of a long lifetime, and which can be opened and closed frequently. <P>SOLUTION: The vacuum valve 1 of one embodiment has a pair of electrodes 8 and 11 which can be mutually connected and separated, a vacuum envelope 2 containing the pair of electrodes 8 and 11 and a bellows 14 which enables the pair of electrodes 8 and 11 to mutually connect and separate, while keeping a vacuum state in the vacuum envelope 2. The bellows 14 of the vacuum valve 1 is so disposed that the length of the bellows 14 when the connecting conditions of the pair of electrodes 8 and 11 becomes shorter than the free length of the bellows 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vacuum valve for opening and closing an electric circuit.

  A vacuum valve is used for opening and closing an electric circuit. Generally, a vacuum valve includes a pair of electrodes that can be contacted / separated relatively and a vacuum vessel that houses the pair of electrodes.

  The vacuum valve includes a bellows for allowing the pair of electrodes to contact and separate while maintaining a vacuum state with respect to the vacuum container.

  The bellows has a peak portion and a valley portion in the cylindrical portion (side surface portion), and expands and contracts when the pair of electrodes are opened and closed. Bending stress is generated in the peaks and valleys.

  Fatigue damage accumulates due to this stress and repeated opening and closing of the electrode at the peak and valley of the bellows, and a fatigue crack may occur. When this fatigue crack penetrates in the plate thickness direction, the degree of vacuum in the vacuum vessel is lowered, the withstand voltage is lowered, the arc generated between the electrodes is in a discharge state, and it is difficult to shut off by the vacuum valve. There is a case.

  Thus, the bellows is an important component that affects the life of the vacuum valve. In order to realize frequent opening and closing of the vacuum valve, it is necessary to extend the life of the bellows.

  Factors affecting the life of the bellows include the bellows thickness, the radius of curvature of the bellows peak and valley, and the bellows material.

  Japanese Patent Publication No. 7-75133 discloses an invention in which the thickness of the bellows is limited to 0.09 mm to 0.07 mm. Thereby, the maximum stress is relieved and the life of the bellows is extended.

  Japanese Examined Patent Publication No. 5-33485 discloses an invention in which the radius of curvature of the valleys at both ends of the bellows is made larger than the other radius of curvature, thereby extending the life of the bellows.

Japanese Patent No. 1459316 discloses an invention in which the bellows is made of a nickel-based alloy to extend the life of the bellows.
Japanese Examined Patent Publication No. 7-75133 Japanese Patent Publication No. 5-33485 Japanese Patent No. 1459316

  However, in recent years, vacuum valves have become increasingly versatile, and large-scale vacuum valves may be required to be frequently opened and closed.

  In such a case, if a bellows having a thickness of 0.1 mm or less as described in Patent Document 1 is used, sufficient strength to support the spring constant and the movable shaft portion may not be obtained.

  When a bellows having a thickness of 0.1 mm or less is attached to a vacuum switch and opened and closed, various adverse effects may occur, for example, misalignment may occur where the fixed shaft and the movable shaft do not coincide.

  As described in Patent Document 2 above, when the curvature radius of the valleys at both ends of the bellows is made larger than other curvature radii, and as described in Patent Document 3 above, Long life is achieved when a nickel-base alloy is used as the material. However, there is still room for improvement in the high-speed opening and closing and the extension of the lifetime of the bellows against further impact force in recent years.

  In addition, due to the effect of high-speed opening and closing and an increase in impact force, a bellows fracture site different from the conventional case may appear, such as a fracture at the peak of the bellows.

  The present invention has been made in view of the above circumstances, and by eliminating the use of the bellows in a state longer than the free length, the bellows has a long life and can be opened and closed frequently. The object is to provide a valve.

  Specific means taken for realizing the present invention will be described below.

  An object of the present invention is to provide a bellows comprising a pair of electrodes that are relatively close to and away from each other and a vacuum vessel containing the pair of electrodes, and enabling the contact and separation of the pair of electrodes while maintaining a vacuum state with respect to the vacuum vessel. The length of the bellows when the pair of electrodes are in contact with each other is solved by the vacuum valve in which the bellows is installed so that the length is shorter than the free length of the bellows. .

  In the present invention, it is possible to extend the life of the bellows and improve the reliability of frequent opening and closing operations.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  When the portion broken at the peak portion of the bellows is cut in the longitudinal direction in order to observe in detail, the bellows is curved in the longitudinal direction. The reason for this bending is thought to be that the strain generated when the bellows was formed from the blank tube remained.

  In the case of a bellows, since the expansion and contraction life depends on the crystal grain size of the material, there is a case where sufficient distortion cannot be removed depending on the material. In such a state, the bellows is longer than the free length on the basis of the free length when the bellows is manufactured (the length when no force is applied from the outside, the length formed naturally) When a pair of electrodes are brought into contact with each other, in addition to the residual stress generated at the time of forming the bellows, a further tensile load is added to the inner surface of the bellows peak portion due to the elongation of the bellows. As a result, a great amount of tensile stress is applied to the inside of the bellows crest and the lifetime of the bellows is reduced.

  In the present embodiment, in view of the above situation, the life of the bellows is increased by eliminating the use of the bellows in a state longer than the free length.

  Hereinafter, in order to relieve the stress of the peak portion of the bellows, a vacuum valve that realizes a long life of the bellows by not using the bellows with a length longer than the free length of the bellows having residual stress will be described.

  FIG. 1 is a cross-sectional view showing an example of an electrode contact state of the vacuum valve according to the present embodiment.

  FIG. 2 is a cross-sectional view showing an example of the electrode non-contact state of the vacuum valve according to the present embodiment.

  1 and 2 show a cross section of the vacuum valve 1 in the contact driving direction.

  The vacuum valve 1 is suitable for frequent opening and closing. The vacuum valve 1 includes a vacuum container 2. The vacuum vessel 2 is formed with a fixed-side sealing metal fitting 4 on the fixed-side opening end surface of the cylindrical insulating vessel 3 and a movable-side sealing metal fitting 5 on the movable-side opening end surface of the insulating vessel 3. Yes.

  The fixed-side opening end face and the movable-side opening end face of the insulating container 3 are hermetically sealed by the fixed-side sealing fitting 4 and the movable-side sealing fitting 5, respectively. As the insulating container 3, for example, an alumina porcelain is used.

  A fixed energizing shaft 6 is provided on the fixed side of the vacuum vessel 2 so as to penetrate the fixed-side sealing fitting 4. A fixed-side electrode 8 is provided via a coil 7 at the end of the fixed energizing shaft 6 on the inside of the vacuum vessel 2. The fixed energizing shaft 6 serves as one electric circuit.

  A movable energizing shaft 9 is provided on the movable side of the vacuum vessel 2 so as to penetrate the movable-side sealing fitting 5. A movable electrode 11 is provided at the end of the movable energizing shaft 9 on the inside of the vacuum vessel 2 via a coil 10. The movable energizing shaft 9 serves as the other electric path.

  The fixed side electrode 8 and the movable side electrode 11 can be contacted and separated. The fixed side electrode 8 and the movable side electrode 11 are surrounded by a shield 12. The shield 12 is further surrounded by the vacuum vessel 2.

  The shield 12 has an insulation resistance in which the metal vapor generated from the electrodes 8 and 11 and the molten metal adhere to the inner wall of the insulating container 3 when the fixed side electrode 8 and the movable side electrode 11 are opened and closed inside the vacuum container 2. Is provided to prevent the deterioration.

  A bellows cover 13 is provided at a position between the shield 12 and the inner surface of the movable side fitting 5 on the movable side energizing shaft 9.

  The bellows cover 13 prevents the metal vapor and molten metal generated from both the electrodes 8 and 11 from adhering to the bellows 14 when the fixed side electrode 8 and the movable side electrode 11 are opened and closed inside the vacuum vessel 2. Is provided.

  One end of the bellows 14 is connected to the inner surface side of the movable side sealing metal fitting 5, and the other end of the bellows 14 is connected to the bellows cover 13 provided on the contact side of the movable side energizing shaft 9. By providing the bellows 14, the movable electrode 11 can be moved in the axial direction while maintaining the degree of vacuum of the vacuum vessel 2.

  Further, in the present embodiment, in order to enable frequent opening and closing of the vacuum valve 1, the length of the bellows 14 when the fixed side electrode 8 and the movable side electrode 11 are in contact with each other is set to be longer than the free length of the bellows. Also, a bellows 14 is installed so as to be in a short state. The maximum length of the bellows 14 introduced into the vacuum valve 1 (that is, the length of the bellows 14 when the fixed electrode 8 and the movable electrode 11 are in contact) is 97% of the free length of the bellows 14. The following is preferable.

  Below, the creation method of the bellows 14 which concerns on this Embodiment is demonstrated.

  FIG. 3 is a diagram illustrating an example of a method for creating the bellows 14 according to the present embodiment.

  A crest and a trough are formed in the cylindrical portion (side surface portion) of the cup-shaped raw tube 16 by a hydroforming method, whereby the bellows 14 is created. In the hydroforming method, a hydroforming metal fitting 17 that covers the cup-shaped raw tube 16 is used. Concentric concave portions and convex portions are formed on the inner surface of the cylindrical portion of the hydroformed metal fitting 17. A bellows 14 is created by installing a cup-shaped element tube 16 inside the hydroformed metal fitting 17 and applying pressure to the inside of the cup-shaped element tube 16. In FIG. 3, the installation relationship between the cup-shaped element tube 16 and the hydroformed metal fitting 17 is shown in a sectional view.

  When the bellows 14 is created by the hydroforming method, the peak portion of the bellows 14 is formed by expanding the raw tube. Therefore, generally, the thickness of the peak portion of the bellows 14 produced by the hydraulic forming method is thinner than that of the raw tube 16. On the other hand, in the valley of the bellows 14, there is almost no change between the diameter of the valley and the diameter of the raw tube. For this reason, the thickness of the valley portion of the bellows 14 created by the hydroforming method is equal to the thickness of the raw tube 16.

  In the present embodiment, the bellows 14 is in a state having residual stress after application of the hydroforming method.

  For example, a solid solution strengthened nickel-based alloy is used as the material of the bellows 14. The main composition of the bellows 14 is Ni as a base material, further Cr is about 19 to 21%, Fe is about 8% to 10%, Mo is about 8% to 10%, and Nb and Ta are 3% to 5%. It is preferable to contain about%.

  As a more preferable example, it is assumed that the main composition of the bellows 14 includes Ni as a base material, further includes about 20% Cr, about 9% Fe, about 4% Mo, and about 4% Nb and Ta. Can be mentioned.

  In this embodiment,% is weight% (wt%) or mass% (mass%).

  In the vacuum valve 1 according to the present embodiment described above, the expansion / contraction range of the bellows 14 is shorter than the free length of the bellows 14 in order to relieve the stress at the peak of the bellows 14 having residual stress at the peak. Preferably, it is 97% or less of the free length of the bellows 14.

  Thereby, the concentration of stress generated in the peak portion of the bellows 14 can be relaxed, the life of the bellows 14 can be extended, and the vacuum valve 1 suitable for extending the life can be obtained.

  In the present embodiment, the material of the bellows 14 is described as an example of a solid solution strengthened nickel-based alloy. However, the material of the bellows 14 is not limited to this, and is made of, for example, austenitic stainless steel. The extended life of the bellows 14 can also be realized.

  In this embodiment, each component may be rearranged as long as the same operation can be realized, each component may be freely combined, and each component may be freely divided. Some components may be deleted.

(First embodiment)
An example of the bellows 14 according to the above embodiment will be described.

  In this embodiment, the bellows 14 is made from a metal plate of a solid solution strengthened nickel-base alloy. The main composition of the metal plate includes Ni, further includes about 20% of Cr, about 3.5% of the total amount of Nb and Ta, about 9% of Mo, and about 5% of Fe.

  Using this metal plate, an element tube 16 having a cylindrical portion diameter of 62 mm and a wall thickness of 0.2 mm is formed.

  Next, a hydroforming method is applied to the raw tube 16 to create a bellows having an inner diameter of 62 mm, an outer diameter of 85 mm, a number of peaks of 11 and a free length of 65 mm.

  Next, welding is performed on two of the bellows having a free length of 65 mm, and welding is performed, so that a bellows 14 having a free length of 130 mm is created.

  The bellows 14 having a free length of 130 mm is incorporated in the vacuum valve 1 according to the above embodiment, and attached to a switch that can freely adjust the opening / closing speed and opening / closing stroke, and an opening / closing life test is performed.

  As test conditions for the open / close life test, an open / close stroke distance corresponding to the bellows expansion / contraction amount is set to 30 mm, an average charging speed is set to 0.5 m / s, and an average opening speed is set to 1.0 m / s.

  In this open / close life test, the bellows breakage is determined by the fact that a voltage is applied between both electrodes of the vacuum valve 1 every 10,000 times and a predetermined withstand voltage cannot be maintained. to decide.

  In order to investigate the case where the bellows 14 extends beyond the free length, it is assumed that the bellows 14 having a free length of 130 mm is attached to the vacuum valve 1 so that the expansion / contraction range is 110 mm to 140 mm and the above open / close life test is performed. In this case, the bellows reached the end of its life after 61,000 times.

  On the other hand, in order to examine the case where the bellows 14 is attached to the vacuum valve 1 so as not to extend beyond the free length, the expansion range of the bellows 14 having a free length of 130 mm is 95 mm to 125 mm (bellows 14). It is assumed that the maximum length of the bellows 14 is 96% with respect to the free length, and the above open / close life test is performed. In this case, the bellows 14 reached the end of its life after 145,000 times.

  Thus, by attaching the bellows 14 to the vacuum valve 1 so that it does not extend beyond the free length, it is possible to dramatically extend the life of the bellows 14 and the vacuum valve 1.

(Second embodiment)
Assume that the bellows 14 having a free length of 130 mm in the first embodiment is attached to the vacuum valve 1 / operation mechanism so that the expansion / contraction range is 105 mm to 135 mm, and the open / close life test in the first embodiment is performed. In this case, the bellows 14 slightly extended beyond the free length, and the lifetime was 70000 times.

  In contrast, the bellows 14 having a free length of 130 mm in the first embodiment has an expansion / contraction range of 90 mm to 120 mm (the maximum length of the bellows 14 is 92% with respect to the free length of the bellows 14). It is assumed that the open / close life test in the first embodiment is performed by attaching the vacuum valve 1 to the operation mechanism. In this case, the extension of the bellows 14 was suppressed more than in the case of the first embodiment, and the number of lifetimes increased to 150,000 times.

  The present invention is effective in the field of vacuum valves that perform opening and closing operations of electric circuits.

Sectional drawing which shows the example of the electrode contact state of the vacuum valve which concerns on embodiment of this invention. Sectional drawing which shows the example of the non-electrode contact state of the vacuum valve which concerns on the embodiment. The figure which shows the example of the production method of the bellows concerning the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vacuum valve, 2 ... Vacuum container, 3 ... Insulation container, 4 ... Fixed side sealing metal fitting, 5 ... Movable side sealing metal fitting, 6 ... Fixed electricity supply shaft, 7, 10 ... Coil, 9 ... Movable electricity supply shaft, 11 ... movable side electrode, 12 ... shield, 13 ... bellows cover, 14 ... bellows, 16 ... elementary tube, 17 ... hydroformed metal fitting

Claims (6)

A bellows comprising a pair of electrodes that can be relatively contacted and separated, and a vacuum vessel that houses the pair of electrodes, the bellows for allowing the pair of electrodes to be contacted and separated while maintaining a vacuum state. A vacuum valve comprising:
The vacuum valve, wherein the bellows is installed so that the length of the bellows when the pair of electrodes are in contact is shorter than the free length of the bellows. The vacuum valve according to claim 1.
The bellows
A vacuum valve characterized in that a blank pipe having a cylindrical portion and a bottom portion is created, and a crest portion and a trough portion are formed by a hydraulic forming method on the cylindrical portion of the blank tube. The vacuum valve according to claim 1 or 2,
The said bellows has a residual stress, The vacuum valve characterized by the above-mentioned. The vacuum valve according to any one of claims 1 to 3,
The length of the bellows when the pair of electrodes are in contact is 97% or less of the free length of the bellows. The vacuum valve according to any one of claims 1 to 4,
The bellows is made of a solid solution strengthened nickel-base alloy. The vacuum valve according to claim 5,
The bellows is made of Ni as a base material, further contains about 5% of Cr, about 9% of Fe, about 4% of Mo, and about 4% of the total amount of Nb and Ta. .

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