Vacuum interrupter

Abstract

The vacuum interrupter (1) according to the invention has a cover bottom (16) which comprises an insertion opening (17) for a moving contact rod (9) which is axially movable and carries a moving contact (4). The moving contact rod (9) is guided out of the vacuum interrupter (1) in a vacuum-tight manner by means of a bellows (12). The bellows (12) has a centering shoulder (122) which is formed by a tubular end piece of the bellows (12) extending in parallel with the longitudinal axis (129) of the bellows (12) and which is inserted into the insertion opening (17). The bellows (12) additionally has a bellows bottom (123) which is located on the centering shoulder (122), extends substantially transversely to the longitudinal axis (129) of the bellows (12) and has a through-opening (126) for the moving contact rod (9).

Description

[0001] The invention relates to a vacuum switching tube.

[0002] In a vacuum interrupter, it is common practice to seal the transition between the moving contact rod, which carries the moving contact, and the vacuum interrupter housing using a metallic bellows. It is known to solder one end of the bellows to a housing flange of the vacuum interrupter and the other end to the moving contact rod. In technical literature, the moving contact rod is also referred to as the moving contact connection bolt, switching rod, drive rod, or contact stem.

[0003] US 4,071,727 A (Crouch et al.) January 31, 1978 describes a device in which an upper end 32 of the bellows 30 is connected to the moving contact rod 26 and a lower end 33 of the bellows 30 is attached to an inner circumference of an end cap 15 of the housing. A guide device 35 is provided to guide the moving contact rod 26 during switching operations. This guide device consists of a metal bushing 36 surrounding the moving contact rod 26 with plastic inserts 40, 42 and a radially outwardly extending flange 38 at the lower end of the metal bushing 36, which is centered and fixed to the end cap 15 by means of a screw device.

[0004] DE 102 20 110 A1 (ABB Patent GmbH) 13 November 2003 describes a bellows 33 arranged between a housing cover 24 and a support collar 32 of a contact rod 30, which seals the interior of a vacuum switching chamber 10 gas-tight to the outside and is fixed to an end face of a base 27 of the housing cover 24.

[0005] DE 10 2008 018 531 B3 (Siemens AG) 17 September 2009 describes a connection of a bearing 12 of the drive rod 10 to a housing cover 9 by means of a locking hook 22.

[0006] US 4 492 837 A (Crouch et al.) 08-01-1985 describes a vacuum switching tube according to the preamble of claim 1.

[0007] Since the issues of fixing the bearing of the moving contact rod and the connection and centering of the bellows on the lid base are interconnected, there is always a need for constructive solutions that enable simple and cost-effective mounting of the moving contact rod and fixing of the bellows.

[0008] It is therefore the object of the present invention to provide a corresponding vacuum switching tube.

[0009] This problem is solved according to the invention by the vacuum switching tube according to independent claim 1. Advantageous embodiments of the vacuum switching tube according to the invention are the subject of the dependent claims.

[0010] The vacuum switching tube has a switching chamber enclosed by a housing, in which a fixed contact and a moving contact are arranged. The moving contact is located at one end of a moving contact rod, which extends axially out of the vacuum switching tube. By axially moving the moving contact rod, the moving contact can be moved relative to a fixed contact. The moving contact rod runs vacuum-tight through a cover of the housing; for this purpose, the cover has a through-hole in its base through which the moving contact rod is guided.

[0011] The passage of the moving contact rod through the opening in the cover base is kept vacuum-tight by means of a metallic bellows. The bellows is a corrugated metal tube which, due to its numerous corrugations, can be axially expanded and compressed, thus enabling the axial movement of the moving contact rod required during switching operations of the vacuum switching tube, without compromising the vacuum seal in the area where the moving contact rod passes through the cover base.

[0012] The bellows features a centering element formed by a tubular end piece running parallel to the bellows' longitudinal axis. This centering element is inserted into the through-hole and thus centers the bellows relative to the lid base.

[0013] The bellows has a bellows base. The bellows base is located at the centering attachment, specifically at the end of the centering attachment. The bellows base has a through-opening through which the moving contact rod is guided.

[0014] The bellows base is located at the end of the centering attachment facing away from the moving contact.

[0015] The invention takes advantage of the fact that technologies are now available in which a bellows is manufactured not from a tube, but from a sleeve with a base. Thus, the bellows has a base in which a through-opening of a suitable shape can be easily created, for example, by punching or laser cutting. Various known methods exist for manufacturing a sleeve with a base, such as deep drawing.

[0016] The bellows base can be used to receive and secure a bearing for the moving contact rod, while simultaneously centering and securing the bellows to the cover base by means of the centering projection and the last bellows shaft. This eliminates the need for an additional device on the cover base for centering the bellows, such as a bearing cap. Thus, the invention offers a cost-effective and simple solution for mounting the moving contact rod and fixing the bellows.

[0017] According to a preferred embodiment of the invention, the bellows base extends substantially transversely to the longitudinal axis of the bellows. The bellows base need not be precisely perpendicular to the longitudinal axis of the bellows in all its areas; angular deviations are permissible according to manufacturing tolerances. In this way, the bellows base forms a contact and mounting surface for other components to be mounted on the vacuum switching tube, such as a bearing for the moving contact rod resting against the bellows base. Since the bellows is manufactured from a sleeve having a base, the bellows base extends substantially transversely to the longitudinal axis of the bellows without the need for further forming steps.

[0018] According to a preferred embodiment of the invention, the bellows and bellows base are manufactured as a single piece. This takes advantage of the fact that technologies are now available in which a bellows is manufactured not from a tube, but from a sleeve with a base. Thus, the bellows has a bellows base. Furthermore, this avoids seams that can lead to gas leaks. Various known methods exist for manufacturing a sleeve with a base, such as deep drawing.

[0019] According to a preferred embodiment of the invention, the through-opening in the bellows base has a smaller clear diameter than the through-opening in the cover base. Thus, the bellows base, whose dimensions are determined by the difference in diameter, can be used to fix a bearing of the moving contact rod.

[0020] According to a preferred embodiment of the invention, the centering projection has an outer diameter that corresponds to the inner diameter of the through-hole in the lid base. In this way, the centering projection fits precisely into the through-hole without noticeable play, thus enabling accurate centering of the bellows with respect to the lid.

[0021] According to a preferred embodiment of the invention, the bellows is connected to the lid base at the outer circumference of the centering projection and / or in the region of the flank of the last bellows shaft extending towards the centering projection. This ensures reliable fixation and a vacuum-tight connection of the bellows to the lid.

[0022] According to a preferred embodiment of the invention, a bearing serving to guide the moving contact rod is inserted into and secured in the through-opening in the bellows base. Thus, the bellows base can be used to fix a bearing of the moving contact rod. Because the bellows base can be used to receive and secure a bearing of the moving contact rod, centering the bellows relative to the housing cover simultaneously achieves centering of the bearing relative to the housing cover. The centering accuracy, which was previously determined by two independent centering steps—centering of the bellows and centering of the bearing—can be improved by reducing it to a single centering step, namely centering the bellows relative to the housing cover, as is possible according to the invention.

[0023] According to a preferred embodiment of the invention, the through-opening in the bellows base has projections and recesses, and the bearing has a contour on its outer circumference corresponding to these projections and recesses, so that the bearing provided for guiding the moving contact rod can be inserted into the through-opening and fixed to the bellows base in the manner of a bayonet fitting. A bayonet fitting is a mechanical connection that can be quickly formed and released.

[0024] A bearing designed to guide the moving contact rod can also be fixed to the bellows base by additional or alternative mechanical connections between the bearing and the bellows base, e.g., by a snap connection. A snap connection can be implemented, for example, by a snap mechanism with a snap hook and / or snap lugs.

[0025] According to a preferred embodiment of the invention, the bellows has a bellows bushing in the form of a pipe extension, which serves as a bearing for the moving contact rod. Integrating the bearing of the moving contact rod into the bellows further simplifies the design. To manufacture the bellows bushing, the bellows base can be reshaped to create a kind of extension of the bellows; this extension, in the form of a bellows bushing, can then function as a bearing that guides and positions the moving contact rod. A separate bearing, which would otherwise have to be arranged as a separate part on the bellows, can be completely eliminated.

[0026] According to a preferred embodiment of the invention, the bellows bushing, which functions as a bearing for the moving contact rod, is connected to the bellows base. This can be achieved by forming the bellows bushing through a deformation of central areas of the bellows base. However, alternative embodiments are also possible in which the bellows base is designed as a separate component that is connected to the bellows base, e.g., by soldering.

[0027] According to a preferred embodiment of the invention, the bellows, including the bellows base and the bellows bushing, is manufactured in one piece. This is simpler and more cost-effective, for example, by deep drawing, than manufacturing the bellows, comprising the bellows base and the bellows bushing, by joining two or more parts. This approach takes advantage of the fact that technologies are now available in which a bellows is manufactured not from a tube, but from a sleeve with a base. Thus, the bellows has a base from which the bellows bushing can also be formed. Furthermore, manufacturing a bellows with the bellows base and the bellows bushing in one piece avoids seams that could lead to gas leaks.

[0028] According to a preferred embodiment of the invention, the bellows bushing has one or more sliding bushings on its inner circumference, which serve as sliding bearings for the moving contact rod. If the bellows bushing forming the bearing of the moving contact rod is made of a metallic material, e.g., the metal of the bellows, sliding bushings can be used. z. B. made of plastic, especially a plastic with good sliding properties such as z. B. Polytetrafluoroethylene, or PTFE for short, improves the bearing's sliding properties. This has the advantage of improving the axial movement of the moving contact rod.

[0029] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more easily understood through the following description of the drawings. These drawings are shown schematically and not to scale: FIG 1 a section of a known vacuum switching tube; FIG 2 a section of a connection of a bellows according to a first known embodiment; FIG 3 a section of a connection of a bellows according to a second known embodiment; FIG 4 a section of a connection of a bellows according to a first embodiment of the invention; FIG 5 a top view of a bellows bottom; and FIG 6 a section of a connection of a bellows according to a second embodiment of the invention.

[0030] FIG 1 Figure 1 shows a vacuum switching tube 1 known in the prior art, with a switching chamber 2 enclosed by a housing 5, in which a fixed contact 3 and a moving contact 4 are arranged. The fixed contact 3 is located at one end of a fixed contact rod 10, which is vacuum-tightly sealed from the vacuum switching tube 1 by a first metallic cover 7, e.g., by soldering the fixed contact rod 10 and the cover 7. The moving contact 4 is located at one end of a moving contact rod 9, which is slidably and rotationally secured by a bearing 13 fixed to a second cover 8 and extends from the vacuum switching tube 1 through the second cover 8. By means of the moving contact rod 9, the moving contact 4 can be brought into contact with the fixed contact 3 in a closing operation and moved to a distance from the fixed contact 3 in an opening operation.The lids 7, 8 together with an insulating cylinder 6 arranged between them, which may be made of ceramic material, form the vacuum-tight housing 5 of the vacuum switching tube 1.

[0031] The passage of the moving contact rod 9 through the second cover 8 is held vacuum-tight by means of a metallic bellows 12, the first end of which is connected to the inner circumference of a circular through-hole 17 located in a cover base 16 of the second cover 8, and the second end of which is connected to a projection 11 of the moving contact rod 9, referred to as a bellows cap, e.g., by soldered connections. The bearing 13 comprises a perforated bearing flange 14 and a tubular guide element 15, which is concentrically attached to and connected with the bearing flange 14; the bearing 13 can be manufactured as a single piece. The bearing 13 can be made of plastic. The bearing flange 14 is centered and fixed to the cover base 16, e.g., by means of a screw connection, as shown in US4071727A (Crouch et al.), or by means of a bearing cap, as shown in FIG 2 shown.

[0032] FIG 2 Figure 1 shows a cross-section of a connection of a bellows 12 according to a first known embodiment. A cover plate 16 has a circular through-hole 17, which is enclosed by a circular circumferential edge of the cover plate 16. A guide element 15 of a bearing 13 of a moving contact rod 9, which has a bearing flange 14 and the guide element 15, is inserted into the through-hole 17 of the cover plate 16, as shown in Figure 1. FIG 1 The bellows 12 is shown and inserted. It has a centering projection 122, formed by a tubular end piece of the bellows 12 running parallel to its longitudinal axis 129. The outer circumference of the centering projection 122 rests against the circularly circumferential edge of the cover base 16, which encloses the through-hole 17 of the cover flange 16. In this way, the bellows 12 is centered relative to the through-hole 17 of the cover base 16. For fixation, the bellows 12 is soldered to the cover base 16 in the areas of the centering projection 122 and to a flank 121 of the last bellows shaft 125 extending towards the centering projection 122. This design allows for easy centering of the bellows 12 relative to the cover base 16, but it also means that an additional component, e.g., a screw device or, as in FIG 2 As shown, a bearing cap 18 is required, attached to the bottom of the cover 16, in which the bearing flange 14 and thus the bearing 13 are inserted and held in a non-displaceable position.

[0033] FIG 3 shows a cross-section of a connection of a bellows 12 according to a second known embodiment, in which the bellows 12 is as in FIG 2 trained. As with the in FIG 2 In the embodiment shown, the cover base 16 also has a circular through-hole 17 in this embodiment, which is enclosed by a circular circumferential edge of the cover base 16. In contrast to the embodiment shown in FIG 2 In the embodiment shown, the end face 161 of the lid base 16 has a FIG 3 In the illustrated embodiment, a recess with a radial width L forms a step along its edge enclosing the through-hole 17. This recess was created, for example, by a clamping manufacturing process. Within the recess, the cover base 16 has a reduced thickness than outside this area. The annular surface 160 of the cover base 16, formed by the recess and set back from the level of the end face 161, constitutes a centering surface 160 on which the end, more precisely, the end face, of the centering projection 122 of the bellows 12 rests. The outer circumference of the centering projection 122 abuts an edge that forms a step between the centering surface 160 and the end face 161 of the cover base 16. The bellows 12 is soldered to the cover flange 16 in the area of ​​this edge and / or in the area of ​​the centering surface 160. This type of centering of the bellows 12 is, compared to the one in FIG 2 The design shown is more complex, but has the advantage that the cover base 16 can extend further towards the moving contact rod 9, by the radial width L beyond the outer circumference of the centering projection 122 of the bellows 12 inwards towards the longitudinal axis 129 of the bellows 12. The accessibility of the edge of the cover base 16 enclosing the through-hole 17 and the independence of the design of this edge from the shape of the centering projection 122 of the bellows 12 opens up the possibility of positioning the bearing 13 differently than in the FIG 2 to attach the design shown on the bottom of the lid 16, e.g. by means of a bayonet fitting or by means of a snap hook, possibly made of plastic, as shown in DE 10 2008 018 531 B3.

[0034] FIG 4 shows a cross-section of a bellows connection according to a first embodiment of the invention. The bellows 12 has, in addition to the features shown in the FIG 2 and 3The elements shown additionally include a bellows base 123 closing the centering projection 122 with a through-opening 126 produced, for example, by punching or laser cutting, see FIG 5 The bellows 12 is centered and fixed to the bottom of the lid 16, as shown in FIG 2 shown by the cylindrical centering projection 122, to which the bellows base 123 is attached, and the flank 121 of the last bellows shaft 125 extending towards the centering projection 122. To fix the bellows 12 so that the longitudinal axis 19 of the moving contact rod 9 coincides with the longitudinal axis 129 of the bellows 12, the bellows 12 is soldered to the cover base 16 in the area of ​​the centering projection 122 and / or in the area of ​​the flank 121 of the last bellows shaft 125 extending towards the centering projection 122, in front of the centering projection 122. The area of ​​the bellows base 123 of the bellows 12 enclosing the passage opening 126 takes over the function of the cover base 16, which is drawn inwards over the outer circumference of the centering projection 122 of the bellows 12. FIG 3 and enables the bearing 13 to be attached to the bellows base 123 of the bellows 12. An additional component for fixing the bearing flange 14 to the cover flange 16, e.g. a screw device or a bearing cap, is therefore not required.

[0035] FIG 5 Figure 1 shows a top view of a bellows base 123 having a through-opening 126, with which a bayonet fitting can be realized. Three projections 127 and three recesses 128 of the edge of the bellows base 123 enclosing the through-opening 126 alternate in 60-degree segments along the circumference of the through-opening 126. The projections and recesses are viewed with respect to the longitudinal axis 129 of the bellows 12, and the projections 127 have a first radius R1 and the recesses 128 have a second radius R2, which is larger than the first radius R1, measured from the longitudinal axis 129 of the bellows 12.The bearing 13, which has a contour on the outer circumference of its guide part 15 corresponding to the projections and recesses 127, 128, can be inserted into the through opening 126 and mechanically connected to the bellows 12 by a rotation about the longitudinal axis 129 of the bellows 12 relative to the bellows 12 (= bayonet fitting).

[0036] FIG 6 shows a cross-section of a bellows connection according to a second embodiment of the invention. Compared to the one in FIG 4 In the embodiment of the bellows 12 shown, the bellows 12 has been further modified so that, adjoining the bellows base 123, which extends transversely to the longitudinal axis 19 of the bellows 12, the bellows 12 has a bellows bushing 124 in the form of a tube extension. This bellows bushing 124 acts as a bearing for the moving contact rod 9, i.e., it guides and positions the moving contact rod 9 by allowing it to slide along an inner wall of the bellows bushing 124. Since the bellows 12 itself thus forms the bearing for the moving contact rod 9, a separate bearing for the moving contact rod 9, as shown in the FIG 4 The depicted design is necessary, but unnecessary.

Claims

1. Vacuum interrupter (1) having a cover base (16) which has an insertion opening (17) for an axially movable moving contact rod (9) which carries a moving contact (4) and which is routed out of the vacuum interrupter (1) in a vacuum-tight manner by means of a bellows (12), wherein the bellows (12) has a centring appendage (122) which is formed by a tubular end piece of the bellows (12) that runs parallel to the longitudinal axis (129) of the bellows (12) and is inserted into the insertion opening (17), wherein the bellows (12) has a bellows base (123) which is disposed on the centring appendage (122) and has a through-opening (126) for the moving contact rod (9), characterized in that the bellows base (123) is disposed on an end of the centring appendage (122) that faces away from the moving contact (4).

2. Vacuum interrupter (1) according to Claim 1, wherein the bellows base (123) runs substantially transversely to the longitudinal axis (129) of the bellows (12).

3. Vacuum interrupter (1) according to one of the preceding claims, wherein the bellows base (123) is disposed on the end of the centring appendage (122).

4. Vacuum interrupter (1) according to one of the preceding claims, wherein the bellows (12) is made from a sleeve comprising the bellows base (123).

5. Vacuum interrupter (1) according to one of the preceding claims, wherein the through-opening (126) in the bellows base (123) has been generated by punching or laser cutting.

6. Vacuum interrupter (1) according to one of the preceding claims, wherein the bellows (12) is made so as to be integral to the bellows base (123).

7. Vacuum interrupter (1) according to one of the preceding claims, wherein the through-opening (126) in the bellows base (123) has a smaller internal diameter than the insertion opening (17) in the cover base (16).

8. Vacuum interrupter (1) according to one of the preceding claims, wherein the centring appendage (122) has an external diameter which corresponds to the internal diameter of the insertion opening (17) in the cover base (16).

9. Vacuum interrupter (1) according to one of the preceding claims, wherein the bellows (12) is connected to the cover base (16) on the external circumference of the centring appendage (122) and / or in the region of that flank (121) of the last bellows corrugation (125) before the centring appendage (122) that runs out to the centring appendage (122).

10. Vacuum interrupter (1) according to one of the preceding claims, wherein a bearing (13) serving to guide the moving contact rod (9) is inserted into the through-opening (126) in the bellows base (123) and fastened therein.

11. Vacuum interrupter (1) according to Claim 10, wherein the through-opening (126) in the bellows base (123) has protrusions and recesses (127, 128) and the bearing (13) has on its external circumference a contour that corresponds to the protrusions and recesses (127, 128), so that the bearing (13) can be inserted into the through-opening (126) in the manner of a bayonet fastener and fixed to the bellows base (123).

12. Vacuum interrupter (1) according to one of Claims 1 to 9, wherein the bellows (12) has a bellows bushing (124) in the form of a tubular appendage which serves as a bearing for the moving contact rod (9).

13. Vacuum interrupter (1) according to Claim 12, wherein the bellows (12) is made so as to be integral to the bellows base (123) and the bellows bushing (124).

14. Vacuum interrupter (1) according to one of Claims 12 and 13, wherein the bellows bushing (124) adjoins the bellows base (123).

15. Vacuum interrupter (1) according to one of Claims 12 to 14, wherein the bellows bushing (124) has on its internal circumference one or a plurality of sliding bushings which serve as sliding bearings for the moving contact rod (9).

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