EP2140467A2 - Device for monitoring vacuum - Google Patents

Abstract

A leak sensor (1) for monitoring the vacuum in a vacuum switching tube has a deformable partition, particularly in the form of a membrane or a bellows (13). The partition is connected to the vacuum chamber of a vacuum switching tube via a measurement opening (9). When the vacuum chamber of the vacuum switching tube is vented, the membrane or bellows (13) is deformed, said deformation being detectable by a mechanical indicator device (25), an optical device, or an electro-optical device (1).

Description

description

Device for monitoring the vacuum

The invention relates to a device for monitoring the vacuum in a vacuum chamber, in particular in a vacuum switching tubes, having a physical properties as a function of the pressure in the vacuum chamber changing device and a device for detecting the changes in the properties of the device.

Such a device is known from DE 34 24 339 and consists of a pair of electrodes which is arranged in the interior of the vacuum switching tubes and forms an auxiliary spark gap. The auxiliary spark gap is dimensioned such that, in the case of a perfect vacuum in the vacuum switching tube, a current flow which is insufficient for exciting a light-emitting diode occurs. If, however, the pressure in the vacuum interrupter tube increases due to a leak to a higher, not sufficient for proper switching pressure, so flows over the auxiliary spark gap, a current sufficient to bring a diode to light up, when switching on the vacuum interrupters with Help a piezoelectric element, a voltage pulse is generated.

A disadvantage of the known device for monitoring the vacuum is, on the one hand, its complicated mechanism for generating a voltage pulse and, on the other hand, that a measurement can not be carried out during operation of the vacuum interrupter tube.

DE 195 39 535 A1 describes a method for pressure monitoring of a vacuum switching tube, which allows a gas-type-independent, interpretation-free, non-invasive, make contactless measurements during the operation of the vacuum interrupters. For this purpose, it is provided to feed ultrasonic waves into the vacuum switching tubes and to determine the gas density in the vacuum switching tubes from the ratio between reflected and transmitted amplitude. In a modified method, a determination of the stress state of metal flanges or screens is carried out with the aid of ultrasound, wherein acoustic self-resonances are utilized. The change in the internal pressure in a vacuum switching tube leads in particular to a change in the resonant frequency of the components used. From a reduction in the resonant frequency and a change in the damping of the amplitude of the natural oscillations can make a monitor for the pressure.

Based on this prior art, the present invention seeks to provide a device for monitoring the vacuum of a vacuum chamber, which is used in a simple and reliable manner as a leak sensor, which allows in particular during the operation of a vacuum switching tubes continuous monitoring.

This object is achieved according to the invention in that the component is a deformable partition wall between the vacuum chamber and the surroundings of the vacuum chamber and that an extreme value of the deformation of the partition wall can be detected by the device for detecting the changes in the properties of the component.

The invention is based on the finding that a pressure drop in a vacuum chamber, in particular in a vacuum switching tubes generally occurs abruptly and it is sufficient to discriminate two extreme conditions. In a particularly simple embodiment, the deformable partition consists of an elastically deformable membrane, in particular a metallic membrane. This may in particular be designed in the manner of a cracked frog and consist of a spring steel which is bent so that it has a stable and a metastable state. Ventilation of the vacuum interrupters causes the membrane to flex in the steady state until it suddenly jumps to a metastable state due to dents. An embodiment of the membrane with two stable states is alternatively also possible.

According to a further preferred exemplary embodiment, the deformable partition wall is formed by a bellows, in particular a metal bellows. In order to avoid overstressing the bellows and to achieve a limitation of the stroke of the bellows, it is expedient if at least one stop is present, which limits the deformation of the bellows.

The deformation of the serving as a partition membrane or the partition wall forming a bellows is transferable to a display element which is movable between two end positions, which are associated with the non-ventilated and the ventilated state of the vacuum chamber, in particular a vacuum switching tubes.

A particularly simple possibility is that the display element is a dipstick, which is arranged in a Indikatorgehau- se and protrudes at aeration of the vacuum with its free end of the indicator housing.

In a preferred exemplary embodiment, the position of the display element is detected optically or optoelectronically. For this purpose, in particular, a light beam bundle emerging from an optical waveguide can be modulated as a function of the position of the display element.

A particularly simple arrangement results if the light emerging from the optical waveguide can be interrupted on its way to an optical waveguide receiving the light through a diaphragm or by pushing away a mirror.

For manual monitoring, in particular, an arrangement is suitable in which the display element is provided with two filters of different colors, which in each of the two end positions of the display element transmit differently colored light to the light-receiving optical waveguide. It is particularly expedient here if the transmitted light beam has a broad color spectrum and in particular represents a white light.

The invention will be described in more detail below with reference to exemplary embodiments with reference to the drawings.

Show it:

Fig. 1 shows a mechanical device for monitoring the vacuum in a vacuum chamber with a

Indicator bar for indicating a ventilated state,

2 shows a device for monitoring the vacuum, in which a light beam serves to detect the position of a mirror,

3 shows a further exemplary embodiment of an arrangement according to the invention, in which a light radiation bundle is interruptible by means of a shadow stop, and

Fig. 4 shows a device for monitoring the vacuum in a vacuum chamber with an optical arrangement, which allows the ventilated and the non-ventilated state of a vacuum chamber to assign different colors.

In Fig. 1, a device for monitoring the vacuum of a vacuum chamber is shown schematically in section, which is hereinafter referred to briefly as leak sensor 1. The leak sensor 1 is attached to the housing 3 of a vacuum switching tubes not shown in detail in Fig. 1, in which a high vacuum must be maintained in order to ensure their functionality. Various causes, such as corrosion, electrical Außenuberschlage in the ceramic of the vacuum tubes or material defects can lead to the fact that vacuum control tubes are vented. In such cases, the pressure in the interior of the vacuum interrupters often abruptly increases, so that an accurate internal pressure measurement is not required to monitor the operability.

The leak sensor 1 illustrated in FIG. 1 is therefore designed so as to indicate, depending on the state of aeration of the vacuum of a vacuum switching tube, whether a vacuum exists or not.

On the housing 3, in the embodiment shown in FIG. 1, a cylinder neck 5 is fastened, on which a pot-shaped indicator cap 7 is fastened by gluing, welding or screwing. In the housing 3 of the Vakuumsehaltröhre a Meßoffnung 9 is provided, which tastes in the interior 11 of a metal bellows 13. The bellows 13 shown schematically in Fig. 1 preferably has a plurality of bellows shafts, so that a sufficient stroke and a sufficient force are available when the bellows 13 expands from the initial position shown in Fig. 1. The bellows 13 is connected at its lower bellows 15 to the housing 3 vacuum-tight, in particular welded.

The upper in Fig. 1 Balgende carries a control disk 17 and not shown in the drawing means for sealing the vacuum and the bellows 13th

The cylinder neck 5 of the leak sensor 1 has a cylindrical inner wall 19, in which at least one axially extending recess 21 is provided, and in which at least one attached to the control disk 17 stop finger 23 engages. The recess 21 forms for the stop finger 23 in Fig. 1, a lower and an upper stop. The stops are each associated with the extreme values of the deformation of the bellows 13 and thus limit the stroke of the bellows 13 and the control disk 17th

On the control disk 17, an indicator rod 25 is fixed, which protrudes with its free end in a Indikatoroffnung 27, which is formed in the indicator cap 7.

In the illustrated in Fig. 1 maximum compression of the bellows 13, which is associated with the non-ventilated vacuum interrupters, the free end of the indicator rod 25 is withdrawn and thus hidden. However, if a ventilation of the vacuum chamber of the vacuum interrupter tubes takes place, the bellows 13 of the leak sensor 1 expands so far until the striking finger 23 in the recess 21 at the other end strikes. In this case, the control disk 17 and attached to it indicator rod 25 moves out of the Indikatoroffnung 27 so far out, so that the free end of the indicator rod 25 is clearly visible from the outside. This is especially the case

Case, when the free end of the indicator rod 25 is marked in accordance with color, in order to obtain a good contrast to the color of the outside of the indicator cap 7.

It is also possible to use the free end of the indicator rod 25 when exiting the indicator cap 7 not only as a visual display, but as Betahtigungsstoßel for the generation of a warning signal.

Vacuum control tubes are often encapsulated and are then no longer readily visible from the outside.

In the illustrated in Fig. 2 exemplary embodiment of a leak sensor 31, an optical indicator is provided so that even encapsulated vacuum control tubes can be monitored continuously and in a simple and reliable manner with respect to their Beluftungszustandes.

The structure of the leak sensor 31 corresponds, with reference to a number of components, to the exemplary embodiment described in connection with FIG. In Fig. 2, therefore, the same reference numerals have been used for the corresponding parts.

In the leakage sensor 31 shown in FIG. 2, a mirror mount 33, which carries a mirror 35, is mounted on the control disk 17. The mirror 35 may be a plane mirror or a convex mirror. An indicator cap 37 screwed onto the cylinder neck 5, for example, is provided with an optical waveguide connection 39 for an optical waveguide Mistake. The optical waveguide connection 39 shown schematically in FIG. 2 has an optical system which allows the mirror 35 to be acted upon by a bundle of light beams which, after being reflected by the mirror 35, returns to the optical waveguide via the optical waveguide connection 39. This is connected via a not shown in the drawing optical decoupling device with a digital display unit.

The leakage sensor 1 shown in Fig. 2 allows a simple way to monitor the vacuum in a vacuum chamber, in particular the vacuum chamber of a vacuum switching tubes. If a ventilation affecting the function of the vacuum switching tubes occurs, the bellows 13 deforms and thereby moves the mirror 35 out of the beam path of the light fed in via the optical waveguide connection 39. As soon as this is the case, the mirror 35 can no longer reflect back the light beam bundle used as measuring light into the optical waveguide connection 39, so that an alarm signal or leakage signal can be triggered in the connected digital display because of the no longer returning light.

3 shows a further example for the optical signal generation for a leak sensor 41. The components already described in connection with FIGS. 1 and 2 are provided with the already known reference symbols. Deviating from the exemplary embodiment shown in FIG. 2, the mirror holder 33 is replaced by a shading cover 43. The leak sensor 41 has an indicator cap 47 with two optical waveguide connections 49 and 51 facing one another. The arrangement of the optical waveguide connections 49 and 51 is such that, when a vacuum is present after connecting a first and a second optical waveguide, the light of the first optical waveguide can pass through the interior 53 of the indicator cap 47 to the second optical waveguide.

As long as the vacuum switching tubes is not ventilated, thus a light transmission through the indicator cap 47 through. However, the light transmission is interrupted when, as a result of aeration, the bellows 13 expands and, in so doing, the shading screen 43 penetrates into the beam path between the optical waveguide connection 49 and the optical waveguide connection 51. If this is the case, the optical signal transmission is interrupted, which can be exploited to make a corresponding indication opto-electronically in a digital display or to generate a leak signal or leak alarm signal.

Instead of an optoelectronic evaluation of the light emerging from the indicator cap 47, it is also possible to bring this light via an optical waveguide to a location at which a visual inspection can take place directly by monitoring personnel. For this purpose, for example, an ebene end face of an optical waveguide can be used as an indicator light.

Optical control of the ventilation state with two colors, for example the color green for the non-ventilated state of a vacuum switching tube and the color red for the ventilated state of a vacuum switching tube, is possible with an arrangement according to the exemplary embodiment illustrated in FIG.

The exemplary embodiment of the leak sensor 61 shown in FIG. 4 differs from the exemplary embodiment illustrated in FIG. 3 in that, instead of a shading diaphragm, an aperture arrangement 63 with color filters 65, 67 is provided. is used. In the arrangement for a leak sensor 61 shown in FIG. 4, the white light fed from the optical waveguide connection 49 passes via the diaphragm arrangement 63 and the color filter 65 to the optical waveguide connection 51. From there, it is processed optoelectronically or purely visually. For a visual check, it is expedient if the color filter 65 is green, so that then the front side of the light waveguide available to the viewer appears green.

When a leak occurs, the bellows 13 expands as far as it allow the recess 21 and the stopper finger 23. The arrangement is made in the exemplary embodiment according to FIG. 4 in such a way that the color filter 67 assumes the position which was originally occupied by the color filter 65. In this way it is then possible, at the end of the output optical waveguide, a display with a different color, such as a red color represent.

Claims

claims 1. Device (1, 31, 41, 61) for monitoring the vacuum in a vacuum chamber, in particular in a Vakuumschaltroh- re, with its physical properties as a function of the pressure in the vacuum chamber changing device (13) and means for detecting the Variations in the characteristics of the component, characterized in that the component (13) is a deformable partition between the vacuum chamber and the environment of the vacuum chamber and that by the means (17, 25, 33, 35, 43, 63) for detecting the changes in properties of the component (13) an extreme value of the deformation of the partition wall can be detected. 2. Device according to claim 1, characterized in that the partition wall is an elastically deformable membrane. 3. Device according to claim 1, characterized in that the dividing wall is formed by a bellows (13). 4. Device according to claim 3, characterized in that the bellows (13) is a metal bellows. 5. Device according to one of claims 3 or 4, characterized in that the deformation of the bellows by at least one stop (21, 23) is limited. 6. Device according to one of claims 1 to 5, d a d e r c h e c e n e c e in that the deformation of the partition wall (13) on a display element (17, 25, 33, 43, 63) is transferable, which is movable between two end positions. 7. The device according to claim 6, characterized in that the display element is a dipstick (25) which is completely obscured by a Indika- torgehause (7) at the minimum of the deformation of the partition wall (13), and at the maximum of the deformation of the partition ( 13) protrudes from the indicator housing (7) so that its display end is visible. 8. Device according to claim 6, characterized in that, depending on the position of the display element (33, 35, 43, 63, 65, 67), a light beam bundle emerging from an optical waveguide can be modulated. 9. Device according to claim 8, characterized in that the light beam emerging from the optical waveguide can be interrupted by at least one diaphragm (43, 63) on its way to an optical waveguide which receives the light. 10. The device according to claim 9, characterized in that the display element (63) with two differently colored filters (65, 67) equipped aperture is provided so that at each of the two end positions of the display element (63) a different colored light to the light receiving Fiber optic cable (51) passes.