1. Field
The disclosed and claimed concept relates generally to vacuum interrupters and, more particularly, to a bellows for use in an evacuated envelope of a vacuum interrupter.
2. Related Art
Vacuum interrupters are generally known in the relevant art. Vacuum interrupters employ a set of separable contacts that are situated within an evacuated envelope to facilitate the rapid extinction of any arc that may propagate between the separable contacts when they are in the process of separating during a trip event. The two separable contacts, one being movable and the other being fixed, are situated within the evacuated envelope, with the movable contact being connected with a compressible bellows that maintains the evacuated nature of the envelope even during movement of the movable contact. Such vacuum interrupters are themselves typically incorporated into a vacuum circuit interrupter that employs a separate vacuum interrupter on each pole.
While such bellows have been generally effective for their intended purposes, they have not been without limitation. When the set of separable contacts are separated from the closed state, or closed from the open state, the movable contact moves with great speed and thus energy, meaning that one end of the bellows is rapidly accelerated and then rapidly decelerated, while the opposite end of the bellows remains fixed. Since the bellows typically are formed of a thin metal, such bellows have been sometimes known to rupture due to their inability to withstand the mechanical forces inherent in the separation of the separable contacts, repeatedly, for tens of thousands times. It thus would be desirable to provide an improved bellows that meets these and other needs.
An improved bellows for use in a vacuum interrupter includes a plurality of corrugations extending along a central axis, with each convolution including a convolution element and a support element. Each convolution element has a convolution length along the central axis and a convolution height perpendicular to the central axis. In a first embodiment, the convolution height of the various corrugations increases between two ends of the bellows. In an embodiment, the bellows height increases gradually between the two ends, and in another embodiment the convolution height increases in a stepwise fashion. The convolution length can likewise change gradually or stepwise between the ends of the bellows. The convolution height alternatively can remain the same throughout a bellows, but the convolution length may change.
What has greatly limited the ability of know bellows to withstand tens of thousands of opening and closing operations in high impact applications as vacuum interrupters is the continued oscillation of the convolutions even after a movable portion of the vacuum interrupter has come to a complete stop. The oscillations initially result from the kinetic energy given to the elastic convolutions by the external breaker mechanism. In order to damp such oscillations, heat is generated by the repeated elastic deformation cycles of the convolutions.
However, if many of the convolutions of a bellows have a common shape and hence resonant oscillation frequency, such convolutions will oscillate in a synchronized fashion, as if they were a single piece. That is, there will be no relative opening and closing within and between such convolutions. In such a situation, the damping of oscillations in such known bellows occurs generally only at the region between the convolutions having the common shape and the first one or two end convolutions, which are rigid as they are affixed to the outside massive assembly, by way of example. This is why such known bellows have tended to fail at the first one or two convolutions at either end.
The solution presented herein is to provide convolutions having various shapes within the same bellows. This advantageously promotes relative motion of opening and closing, i.e. elastic deformation, within and among many of not all the convolutions of the bellows.
Accordingly, an aspect of the disclosed and claimed concept is to provide an improved bellows for use in an evacuated envelope of a vacuum interrupter, and to provide such an improved vacuum interrupter.
Another aspect of the disclosed and claimed concept is to provide a bellows for use in a vacuum interrupter in which, upon an event that opens or closes a set of closed contacts, vibrations in the bellows are quickly dissipated and the duty of damping the oscillations is distributed across most if not all of the bellows convolutions.
The disclosed and claimed concept is provided with the intention to vary the natural oscillation frequency of many of the convolutions of a bellows. The dominating principle is to resist synchronized movement of the convolutions and to desirably spread the duty of dissipating the energy of the oscillations across many of the convolutions of the bellows.
These and other aspects of the disclosed and claimed concept are provided by an improved bellows for a vacuum interrupter having an evacuated envelope. The bellows in a free state can be generally stated as including a plurality of convolution elements and a plurality of support elements alternately connected together and being symmetric about an axis that extends centrally through the bellows, each adjacent pair of convolution elements being connected with and spaced apart by an intervening support element, and each adjacent pair of support elements being connected with and spaced apart by an intervening convolution element; each convolution element being of a convolution length along the axis and being of a convolution height perpendicular to the axis; each support element being of a spacing length along the axis; and at least one of: at least a first convolution element having a convolution length different than that of another convolution element situated adjacent the at least first convolution element, and at least a first support element having a spacing length different than that of another support element situated adjacent the at least first support element.
Other aspects of the disclosed and claimed concept are provided by an improved bellows for a vacuum interrupter having an evacuated envelope. The bellows in a free state can be generally stated as including a plurality of convolution elements and a plurality of support elements alternately connected together and being symmetric about an axis that extends centrally through the bellows, each adjacent pair of convolution elements being connected with and spaced apart by an intervening support element; each convolution element being of a convolution length along the axis and being of a convolution height perpendicular to the axis; and the convolution height of a first convolution element at or near a first end of the bellows being greater than that of a second convolution element at or near a second end of the bellows.
Other aspects of the disclosed and claimed concept are provided by an improved vacuum interrupter comprising the bellows as set forth in either preceding paragraph. Still other aspects of the disclosed and claimed concept are provided by an improved circuit interrupter comprising a number of the vacuum interrupters and an operating mechanism operatively connected with the number of vacuum interrupters.
A further understanding of the disclosed and claimed concept can be gained from the following Description when read in conjunction with the accompanying drawings in which:
Similar numerals refer to similar parts throughout the specification.
An improved bellows for in accordance with the disclosed and claimed concept is depicted in
One or more of the vacuum interrupters 8 can be incorporated into a circuit interrupter 17 that employs a separate vacuum interrupter 8A, 8B, and 8C on each of a plurality of poles 13A, 13B, and 13C. The circuit interrupter 13 further includes an operating mechanism 15 that is operatively connected with each of the vacuum interrupters 8A, 8B, and 8C to open and close the sets of separable contacts in certain predetermined conditions.
The improved bellows 4 comprises a plurality of convolutions 12 that extend along a central axis 16. When the post 11 moves during an event that causes separation of the separable contacts 10A and 10B, the post 11 moves generally along the direction of the central axis 16. As such, the oscillations that are desirably dissipated after such an occurrence are those that occur along the direction of the central axis 16. In one aspect, the improved bellows 4 rapidly dissipates oscillations along the central axis 16 by making at least certain adjacent convolutions 12 different from one another in various respects. That is, the improved bellows 4 is configured such that the convolutions 12 are not all identical to one another, because an oscillation introduced with respect to a given convolution will be easily transferred to an identical adjacent convolution and so forth until the oscillation rebounds from an end of such a bellows and the oscillation is reflected in the opposite direction from one identical convolution to another. Advantageously, the improved bellows 4 dissipates oscillations that otherwise would occur along the central axis 16 by making many, if not all, of the convolutions 12 different from one another.
As can be understood from
Each convolution element 20 can be said to be of a convolution length 28 as measured along the central axis 16, i.e., parallel therewith, and is of a convolution height measured in a direction generally perpendicular to the central axis 16 and indicated in
The support elements 24 can be said to be of a spacing length 36 in a direction along the central axis 16. The support elements 24 can also be said to have a support radius 40. Similarly, the convolution elements 20 themselves have a convolution radius 44.
In the first embodiment of the bellows 4 depicted generally in
An improved bellows 104 in accordance with a second embodiment of the disclosed and claimed concept is depicted generally in
Similarly in
Thus it can be seen from
A third embodiment of a bellows 204 in accordance with the disclosed and claimed concept is depicted generally in
More particularly, it can be seen that two convolutions 212 have the same convolution length 228A. These same two convolutions 212 have an equal spacing length 236A, an equal support radius 240A, and an equal convolution radius 244A. A pair of convolutions 212 adjacent thereto likewise have an equal convolution length 228B, an equal spacing length 236B, an equal support radius 240B, and an equal convolution radius 244B. However, it can be seen from
It thus can be seen that the bellows 204 has a convolution height 232 that changes progressively from one end to the other, whereas its convolution length 228, its spacing length 236, its support radius 240, and its convolution radius 244 each change in a stepwise fashion. In this regard, it is understood that not all of the convolution length 228, the spacing length 236, the support radius 240, and the convolution radius 244 need to vary in the same fashion as one another. That is, one or more might increase while others stay the same or decrease, in any combination. Another improved bellows 304 in accordance with a fourth embodiment of the disclosed and claimed concept is depicted generally in
While the exemplary bellows 304 in
In this regard, it should be understood that the embodiments depicted in FIGS. 1 and 3-5 each contain various varying properties and that such properties can be combined in other combinations without limitation. By way of example, the stepwise change in convolution length as indicated at the numerals 328A, 328B, 328C, 328D, and 328E could itself be incorporated into the bellows 4 without the other variations that are present in the bellows 304 to provide another embodiment of a bellows in accordance with the disclosed and claimed concept that is not expressly depicted herein. Other combinations of the features depicted herein will be apparent to those skilled in the art.
A fifth embodiment of an improved bellows 404 in accordance with the disclosed and claimed concept is depicted generally in
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.
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Number | Date | Country |
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10 2007 063447 | Apr 2009 | DE |
Number | Date | Country | |
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20120118858 A1 | May 2012 | US |