Vacuum interrupter

A vacuum interrupter includes at least one insulating body, a fixed contact, a fixed contact flange, a moving contact having a longitudinal axis of the moving contact, a moving contact flange, a moving contact bearing, and a bellows. The fixed contact is stationarily disposed in the fixed contact flange, the moving contact is moveably guided in the moving contact bearing and the moving contact is moveably secured to the moving contact flange by the bellows. The bellows is secured to the moving contact flange by a first bellows end and the bellows is secured to the moving contact by a second bellows end. An increased pressure resistance of the vacuum interrupter against ambient pressures over 1 bar is achieved by a sleeve which is secured to the moving contact against movements along the longitudinal axis of the moving contact, and which is guided through the moving contact bearing.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a vacuum interrupter tube for medium-voltage switchgear and high-voltage installations.

Vacuum interrupters from the prior art have a bellows for movably guiding the moving contact of the vacuum interrupter into the vacuum interrupter.

For large strokes and/or long bellows, the problem arises, especially at ambient pressures above one bar (1 bar), that the bellows undergoes deformation during switching operations, for example kinking and/or bending and/or twisting and rubbing against the moving contact. This reduces the service life of the bellows, and thus that of the vacuum interrupter.

SUMMARY OF THE INVENTION

The object of the invention is therefore to reduce or prevent deformation of the bellows and friction of the bellows against the moving contact.

The object is achieved by the independent claim as described below and by the claims dependent on it.

In an exemplary embodiment, the vacuum interrupter has at least one insulating body, a fixed contact, a fixed-contact flange, a moving contact having a longitudinal axis of the moving contact, a moving-contact flange, a moving-contact bearing, and a bellows. The fixed contact is arranged in a stationary manner in the fixed-contact flange, the moving contact is movably guided in the moving-contact bearing, and the moving contact is movably fastened to the moving-contact flange by the bellows, wherein the bellows is fastened to the moving-contact flange by a first bellows end, and the bellows is fastened to the moving contact by a second bellows end, wherein an increased pressure resistance of the vacuum interrupter against ambient pressures over 1 bar is achieved by a sleeve that is fixed on the moving contact, against movements along the longitudinal axis of the moving contact, and that is passed through the moving-contact bearing. In particular, an increased pressure resistance of the vacuum interrupter against ambient pressures over 2 bar, particularly preferably over 4 bar, is also achieved.

The fixing of the sleeve on the moving contact has the effect in this case that the bellows is protected in every switch position, and that there is no possibility of frictional contact between the bellows and the moving contact, or of deformation of the bellows, even when the contact system consisting of the fixed contact and moving contact is closed. This also results in a longer service life at increased ambient pressures. Increased ambient pressures in this case occur, preferably, when the vacuum interrupter is arranged in a pressurized gas, in particular an insulating gas, particularly preferably a gas having a GWP (Global Warming Potential) lower than that of SF6. In particular, the gas with which the switchgear is filled may be a ketone, in particular a fluoroketone, a nitrile, or a gas mixture comprising nitrogen and carbon dioxide.

The sleeve in this case is preferably designed such that it has an inner contour that emulates the outer contour of the moving contact in the region in which the sleeve is fastened on the moving contact.

In an advantageous embodiment, the sleeve is also designed such that, in the assembled state, the distance between the sleeve and the bellows is small.

It is also preferred that the sleeve be arranged on the moving contact in such a manner that the sleeve extends out from the second bellows and through the moving-contact bearing, and the sleeve be fixed on the moving contact, by means of a fastening means, in such a manner that, during the movement of the moving contact, no relative movement along the longitudinal axis of the moving contact occurs between the moving contact and the sleeve.

It is also preferred that the moving contact have at least one moving-contact rod and one moving-contact contact disk, and the second bellows end is directly connected to the moving-contact rod. There may also be a moving-contact body arranged between the moving-contact rod and the moving-contact disk.

It is additionally preferred that the moving contact have at least one moving-contact rod and one moving-contact contact disk, and the second bellows end be connected to the moving-contact rod via a bellows cap. There may also be moving-contact body arranged between the moving-contact rod and the moving-contact disk.

It is also preferred that the sleeve be fixed in position on the moving contact, in the region of the second bellows end and/or in the region of the bellows cap, by means of an press fit. Alternatively, the sleeve is fastened by latching, interlocking, soldering, welding, pressing to a thickened portion of the moving contact that is not emulated by the sleeve, or by other means.

It is also preferred, in particular, that the press fit of the sleeve be effected between the second bellows end and the moving contact, or between the bellows cap and the moving-contact rod. In particular, the sleeve may additionally be interlocked with structural elements at the second bellows end, on the moving contact or on the bellows cap. In particular, projections and/or recesses that engage in each other are suitable for interlocking.

It is also preferred that the moving-contact bearing have a first guide element and the sleeve have a second guide element, wherein the first guide element and the second guide element engage in each other in such a manner that the sleeve is prevented from rotating in the moving-contact bearing. In particular, tongue and groove structures that engage in each other are suitable, i.e. the first guide element is, for example, a groove and the second guide element is, for example, a protruding structural element, a groove engagement, such as a tongue, or vice versa. The structural element in this case may be either fixed, inflexible or flexible. The combined action of the first guide element and the second guide element thus prevents the sleeve from rotating in the moving-contact bearing.

It is further preferred that the sleeve have more than one first guide element, in particular two or three first guide elements, and that the moving-contact bearing have more than one second guide element, in particular two or three second guide elements. The respectively corresponding guide elements in this case engage in each other, i.e. in each case one first guide element and one second guide element act in combination, such that two, three or more first guide elements and second guide elements provide reliable guiding, and thus effective protection against relative rotation between the moving-contact bearing and the sleeve.

It is also preferred that the first guide element and the second guide element engage in each other and mutually limit their movement in such a manner that the sleeve does not slide out of the moving-contact bearing. For example, this is possible by delimitation of the groove in its longitudinal extent, parallel to the longitudinal axis of the moving contact, i.e. in this example, the groove engagement, e.g. a tongue, abuts the end of the groove and thus does not allow any further movement of the sleeve and of the moving contact connected to the sleeve. It is thereby possible to prevent

the bellows from being overstretched, for example during transport, as a result of overstretching in the case of the sleeve, with the moving contact, slipping out of the moving-contact bearing, since the movement is delimited by the first guide element and the second guide element.

The sleeve thus renders possible not only a reduced risk of deformation and, consequently, higher ambient pressures and/or greater bellows strokes and lengths, but also protection against damage to the bellows due to overstretching of the bellows.

It is also preferred that the moving contact rod have a third guide element, and the sleeve have a fourth guide element, which act in combination in such a manner that rotation of the sleeve on the moving-contact rod is prevented.

In particular, it is preferred that the third guide element be formed by a flattened portion on the circumference of the moving-contact rod, in particular of the moving contact, and that the fourth guide element be formed by a raised flattened portion in the sleeve that correspondingly fills up the region having the flattened portion of the moving-contact rod or the moving contact. Alternatively, the moving-contact rod may also have, wholly or partially, an elliptical circumferential profile, an elliptical cross-sectional face, and the sleeve may have an elliptical circumferential profile, an elliptical cross-sectional face.

It is further preferred that the moving-contact rod have more than one third guide element, in particular two or three third guide elements, and that the sleeve have more than one fourth guide element, in particular two or three fourth guide elements. The respectively corresponding guide elements in this case engage in each other, i.e. in each case one third guide element and one fourth guide element act in combination, such that two, three or more third guide elements and fourth guide elements provide reliable guiding, and thus effective protection against relative rotation between the moving-contact and the sleeve.

Owing to the use of the first guide element, the second guide element, the third guide element and the fourth guide element, or multiples of these, the risk of deformation with respect to torsion of the bellows is also reduced, in addition to the reduction of the risk of deformation of the bellows by the sleeve.

It is also preferred that the sleeve be composed of a material that has a low coefficient of friction. In particular, it is preferred that the coefficient of friction for static friction and the coefficient of friction for sliding friction are both low and, particularly preferably, that the coefficients of friction for static friction and sliding friction are the same, which also enables smooth sliding and stopping.

It is additionally preferred that the sleeve be composed of polytetrafluoroethylene or of a modification of polytetrafluoroethylene, i.e. a chemically related material.

It is also advantageous if the second bellows end and/or the bellows cap are/is additionally provided with a bellows shield. The bellows shield in this case prevents and/or reduces deposition of evaporated material on the bellows.

It is also preferred that the bellows shield extend from the second bellows end toward the moving-contact flange.

DETAILED DESCRIPTION OF THE INVENTION

FIG.1shows a section through a vacuum interrupter10having a sleeve90according to the invention. The vacuum interrupter10in this case has insulating elements20, which in this case, optionally, are spaced apart in the region of the contact disks by an intermediate element25.

The vacuum interrupter10additionally has a fixed contact30, in this case consisting of a fixed-contact rod32, a fixed-contact body35and a fixed-contact disk34. The fixed contact30is fastened at one end of the vacuum interrupter10, by means of a fixed-contact flange40, to an insulating body20.

A moving contact50of the vacuum interrupter10is disposed opposite the fixed contact30, the moving contact50in this case consisting, as an example, of a moving-contact rod52, a moving-contact body55and a moving-contact contact disk54.

Fastened on the moving contact50, or more precisely, on the moving-contact rod52, there is a sleeve90, and this sleeve90is extended out from the bellows through a moving-contact bearing70on the moving-contact flange60. In the example shown here, the sleeve90is pressed tightly between the moving-contact rod52and the bellows cap86. The sleeve90is thus fixed on the moving contact52in such a manner that there is no relative movement between the sleeve90and the moving contact50as the moving contact50moves along the longitudinal axis56of the moving contact50. The bellows80, which enables the moving contact50to move within the vacuum interrupter10, is fastened to the moving-contact flange60by a first end82of the bellows80. InFIG.1, the second end84of the bellows80is fastened to the bellows cap86, and the bellows cap86is in turn fastened to the moving-contact rod52of the moving contact50. InFIG.1, the bellows cap86has an optional bellows shield88, which extends from the bellows cap86, along the bellows80, toward the moving-contact flange60.

FIG.2shows a moving-contact rod52, with a sleeve90, which is pressed into the press-in region89between the moving-contact rod52and the bellows cap86, in the direction of the arrow91. Optionally, this press-in region89may also be formed by a thickened portion of the moving-contact rod. In addition, the bellows cap86has a bellows shield88, as shown inFIG.1.

FIG.3shows a portion of a moving-contact rod52with a third guide element53, a sleeve90with a fourth guide element94, and with a second guide element92in the sleeve90that acts in combination with the first guide element72of the moving-contact bearing70, which is not shown here, but which is shown inFIG.4.

FIG.4shows a sleeve90in a moving-contact bearing70, the sleeve90having two second guide elements92,92′, and the moving-contact bearing70having two corresponding first guide elements72,72′. The first guide elements72,72′ in this case are realized as groove engagements, i.e. fixed structural elements. The second guide elements92,92′ in this example are realized as a groove. The groove92in this case extents over the entire length of the sleeve90, but is delimited at one end, thereby preventing the sleeve90and the moving contact50, not shown, that is connected to the sleeve90from slipping through the moving-contact bearing70.

LIST OF REFERENCES