Vacuum switch device and method for producing a vacuum switch device

Abstract

The present invention relates to a vacuum switch device (1), having: a housing (5, 6, 10), at one end of which a fixed contact (2) is arranged; a bellows (7), which is fastened on one side to a flange (10) at the other end of the housing (5, 6, 10) and on the other side to a moving contact (3); and a guide bearing (9, 20, 30) for the moving contact (3), which bearing is fastened to the flange (10) and guides the moving contact (3) in a sliding manner, characterised in that the guide bearing (9, 20, 30) is secured on the flange (10) by an adhesive layer (11). The present invention also relates to a method for producing a vacuum switch device.

Description

[0001] The present invention relates to a vacuum switching device according to the preamble of claim 1 and to a manufacturing method for a vacuum switching device according to the preamble of claim 12.

[0002] From the operating instructions for "3TM Vacuum Contactor 7.2 kV - 15 kV, 3-pole, 4.15 kV - 6.9 kV, 1-pole", order no.: 9229 0106 100 0, Siemens AG 2020, a switching device for medium voltage is known that has a vacuum switching device with an electromagnetic drive. The magnetic drive can exert a magnetic force on a so-called armature plate and attract it. The movement of the armature plate is mechanically translated into a movement that presses a movable contact against a fixed contact within the vacuum switching device. The movable contact is guided out of the vacuum by a flexible spring bellows.

[0003] A vacuum switching device with spring accumulator drive is known from the catalog "Vacuum circuit breaker 3AH4", article no. EMMS-K1511-A041-A6, Siemens AG 2018.

[0004] A vacuum switching device according to the invention comprises, for example, a fluid-tight housing in which a vacuum prevails (or an extremely low gas pressure below 10⁻³ mbar, preferably below 10⁻⁶ mbar). Typically, the housing is partially formed as a ceramic insulating body made of aluminum oxide, which is connected to other components of the housing via a metallic flange. If a movable contact is rapidly pulled away from the fixed contact, for example by means of a spring force, any resulting arc is quickly extinguished. Typically, the current is interrupted in the region of the zero crossing.

[0005] Vacuum switching devices are particularly well-suited for switching alternating current because an arc always breaks at the zero crossing of the current. The movable contact is guided out of the vacuum by a flexible bellows. A guide bearing, preferably made of plastic, is used to stabilize and center the moving contact rod; this bearing is attached to the flange of the moving contact.

[0006] Currently, the guide bearing is often attached using a separate component, a bearing cap. The bearing cap is soldered to the flange of the moving contact during the soldering process and serves as a receptacle for the bearing. After the plastic bearing is inserted, the upper edge of the bearing cap is folded over, for example, to secure the bearing. Solutions are also known in which a type of nozzle is pulled out of the flange to secure the bearing. Furthermore, bearings are known that snap into a locked position during assembly. For this purpose, the plastic bearing is designed to include locking hooks that engage with the flange opening. This design is generally less mechanically stable than the first solution described.

[0007] Furthermore, the publications JP H06 309998 A, DE 33 25 495 A1, JP S57 199926 U, JP S53 31255 U and JP S58 165226 A are known, which deal with vacuum switching devices.

[0008] Based on existing vacuum switching devices, the invention aims to provide a vacuum switching device that is relatively simple and inexpensive to manufacture and enables a long service life.

[0009] The invention solves this problem by means of a vacuum switching device according to claim 1.

[0010] The housing, for example, has a metallic flange as a "lid" and another metallic flange as a "bottom," which are connected to a cylindrical ceramic insulating body (e.g., made of aluminum oxide). The interior of the housing is evacuated.

[0011] A bellows is a component that is coiled in a wave-like, accordion-like fashion, allowing it to be compressed and released with low mechanical resistance while simultaneously being fluid-tight and durable. Bellows are typically made from thin sheet metal.

[0012] A flange is typically a metallic connecting part.

[0013] An adhesive layer according to the invention is a layer less than 5 mm thick containing an adhesive that hardens after application and provides high mechanical strength against tearing during the switching on and off of the vacuum switching device, as well as against twisting and kinking movements during switching. An epoxy resin can be used, at least in part, as the adhesive.

[0014] A guide bearing is a component used to guide the moving contact through the housing. The moving contact is typically bolt-shaped, so the guide bearing provides an elongated hollow cylinder to accommodate the bolt. For cost reasons and due to the material's good sliding properties, guide bearings are often made of plastic and are formed, for example, by injection molding or machining. In such a case, the adhesive layer bonds a plastic guide bearing to a metal flange.

[0015] The adhesive layer between the guide bearing and the flange has the advantage of eliminating previously required manufacturing steps. Securing the plastic guide bearing to the flange with a metal plate that is bent radially inwards for fixation is no longer necessary. This enables faster and more cost-effective production.

[0016] Furthermore, a significant advantage is that, compared to previous designs, the alignment of an anti-rotation device between the rod and the bearing or bearing housing can be carried out following a soldering process to produce the fluid-tight housing. Another advantage is that the extensive bonding achieves particularly high mechanical stability, which increases the service life of the vacuum switching device. A longer service life, in turn, enables cost savings for the customer.

[0017] In a further development of the vacuum switching device, additional mechanical stabilization can be achieved by using a mechanical locking device to press the guide bearing and the flange together and / or prevent the components from being pulled apart. This relieves stress on the adhesive bond and ensures mechanical stability, for example, even in cases where the adhesive layer could loosen due to heating during operation of the vacuum switching device caused by current flow. The mechanical locking device can, for example, be designed as a so-called snap-on nose. This is a spring-loaded device that is fixed at one of its two ends to a cylindrical stabilizing area of ​​the guide bearing and projects from it longitudinally (coaxially to the direction in which the moving contact is guided), i.e., towards the contact surface.In this context, "protrusion" means that a cavity exists between the spring assembly and the stabilizing area. This allows the spring assembly to be pressed against the stabilizing area by applying pressure from the outside inwards, i.e., towards the stabilizing area. The spring assembly is dimensioned so that it is compressed when the guide bearing is slid onto the flange. When the flange comes to rest on the contact surface with the adhesive layer, the spring assembly can snap back out, forming the cavity and locking the flange in place like a barb. It is particularly preferred to subsequently fill the cavity between the spring assembly and the stabilizing area with the adhesive as well. Once cured, the locking mechanism can no longer be released.

[0018] In contrast to previous solutions where a sheet metal plate was used for locking, the contact area to the flange is no longer hollow, but solid to form a contact surface for the adhesive.

[0019] In a preferred embodiment of the vacuum switching device according to the invention, the vacuum switching device is designed for low voltage. Low voltage, as defined in the invention, is characterized by an electrical voltage up to 1 kV.

[0020] In a preferred embodiment of the vacuum switching device according to the invention, the vacuum switching device is designed for medium voltage. Medium voltage, as defined in the invention, is characterized by an electrical voltage between 1 kV and 52 kV.

[0021] In a preferred embodiment of the vacuum switching device according to the invention, the vacuum switching device is designed for high voltage. High voltage, as defined in the invention, is characterized by an electrical voltage above 52 kV.

[0022] In a preferred embodiment of the vacuum switching device according to the invention, the guide bearing has a roughened contact surface on its side facing the flange. Roughened, as used in the invention, means that the surface is no longer smooth. A roughened contact surface has, for example, protrusions and / or depressions of more than 0.1 mm in height or depth. A roughened contact surface offers the advantage of providing a larger surface area for an adhesive, thus achieving greater mechanical strength of the adhesive bond.

[0023] In a further preferred embodiment of the vacuum switching device according to the invention, the flange has a roughened contact surface on its side facing the guide bearing. Roughened, as used in the invention, means that the surface is no longer smooth. A roughened surface has, for example, protrusions and / or depressions of more than 0.1 mm in height or depth. A roughened surface of the flange offers the advantage of providing a larger surface area for an adhesive, thus achieving greater mechanical strength of the adhesive bond.

[0024] In a further preferred embodiment of the vacuum switching device according to the invention, the contact surface has projections. Projections within the meaning of the invention are arbitrarily shaped elevations compared to the plane of the contact surface, which are, for example, raised by at least one millimeter. If recesses are provided on the contact surface, then all non-recessed areas are correspondingly projections within the meaning of the invention. Projections are advantageous because they provide a particularly roughened surface for the adhesive and thus further increase the adhesive force.

[0025] If the movable contact is designed as a bolt, the guide bearing, for example, can also be radially symmetrical. In such a case, the contact surface forms, for example, a ring-shaped circumferential surface.

[0026] In a further preferred embodiment of the vacuum switching device according to the invention, the projections are arranged at least partially transversely to the direction of rotation of the contact surface. The direction of rotation of the contact surface refers to the fact that the guide bearing encompasses the movable contact, i.e., forms a circumferential surface for contacting the flange. With a radially symmetrical design of the guide bearing, this direction of rotation can correspond to a circular path on the contact surface. With a different geometric design of the guide bearing, the direction of rotation can also be polygonal or polygonal. An orientation parallel to the direction of rotation corresponds to an alignment of the projections with their long side along the path around the movable contact, which offers comparatively little resistance to rotational movements during bonding. For example, a longitudinal orientation encompasses an orientation of 0° to + / - 30° relative to the direction of rotation.A perpendicular orientation to the direction of rotation corresponds to an alignment of the projections with their short side along the path of rotation around the moving contact. This means that during bonding, their long side presents itself and offers comparatively high resistance to rotational movements. A perpendicular orientation includes, for example, an orientation of + / - 60° to 90° relative to the direction of rotation.

[0027] In a further preferred embodiment of the vacuum switching device according to the invention, the projections are at least partially wave-shaped. This is advantageous because wave-shaped projections can be easily manufactured for the guide bearing using a plastic injection molding process.

[0028] In a further preferred embodiment of the vacuum switching device according to the invention, the projections are at least partially cuboid in shape. This is advantageous because wave-shaped projections can also be easily manufactured for the guide bearing using a plastic injection molding process.

[0029] In a further preferred embodiment of the vacuum switching device according to the invention, the flange has recesses on its side facing the guide bearing, which are designed to complement the projections on the guide bearing. A complementary surface design of the flange offers the advantage that the projections and recesses can interlock, enabling particularly high resistance to torsional forces during switching. The mechanical strength of the adhesive bond is further improved. Advantageously, in a further development, adhesive gaps can be provided between the recesses and the projections, so that the adhesive can continue to wet the entire surface of both components to be joined.

[0030] In the embodiments described above, projections are provided on the guide bearing and, optionally, recesses on the flange. However, it is equally preferred and technically just as easy to implement to provide projections on the flange and, optionally, recesses on the guide bearing.

[0031] The guide bearing features recesses on its contact surface to collect excess adhesive. This is advantageous because it ensures a consistently thick layer of adhesive is always formed when the guide bearing is pressed against the flange during manufacturing.

[0032] In a further preferred embodiment of the vacuum switching device according to the invention, the recesses are designed as at least one annular circumferential groove.

[0033] In a further preferred embodiment of the vacuum switching device according to the invention, the guide bearing has a boundary wall at the outer edge of the contact surface, which projects at least as high above the contact surface as the projections, and at least one barrier wall is arranged on the side of the contact surface facing the movable contact, which projects at least as high above the contact surface as the projections, wherein the barrier wall encloses a flow opening for a fluid, and wherein the flow opening is arranged between the guide bearing and the movable contact. This has the advantage that the boundary wall and the barrier wall together form an enclosure for the adhesive layer and thus reduce smearing of excess adhesive during manufacturing.

[0034] In a further preferred embodiment of the vacuum switching device according to the invention, the contact surface has at least one bonding opening for receiving adhesive. Tests have shown that, in particular, wetting the inner walls of openings in the contact surface after the adhesive has cured increases the mechanical strength of the adhesive bond. In the simplest case, the bonding openings are bores. It is particularly preferred if, during manufacturing, enough adhesive is applied that the adhesive is forced through the at least one bonding opening to the back (or the side of the guide bearing facing away from the contact surface). A lance of adhesive then forms in the opening, and a thickening forms outside the opening on the back. The adhesive thus forms a rivet-like or...mushroom-like shape at the bonding opening, which increases both the resistance to twisting and the tear resistance of the adhesive bond.

[0035] In a further preferred embodiment of the vacuum switching device according to the invention, the guide bearing has a stabilizing element that tapers towards the fixed contact, on which a radially inwardly bendable spring element is arranged. In the assembled state, this spring element provides a clamping fit of the flange to the contact surface of the guide bearing and / or to an inner surface of the bellows. This additional locking mechanism, in conjunction with the adhesive layer, further increases the mechanical strength.

[0036] In a further preferred embodiment of the vacuum switching device according to the invention, the guide bearing and / or the flange have locking elements for a positive-locking connection between the guide bearing and the flange. For example, detents and recesses can be used as locking elements. A bayonet fitting can also be formed by means of the guide bearing and / or the flange. This further increases the mechanical stability, especially under temperature loads.

[0037] Based on existing manufacturing methods for a vacuum switching device, the invention further aims to provide a manufacturing method for a vacuum switching device that is comparatively simple and cost-effective and enables a long service life for the vacuum switching device.

[0038] The invention solves this problem by means of a vacuum switching device according to claim 12. Preferred embodiments of the manufacturing method according to the invention are explained in dependent claims 13 and 14. These embodiments offer essentially the same advantages as described above for the vacuum switching device according to the invention.

[0039] To better illustrate the invention, the following are shown schematically: Figure 1 shows an embodiment of a vacuum switching device according to the invention, and Figure 2 shows a first embodiment of a guide bearing, and Figure 3 shows a detailed view of the guide bearing according to Figure 2 , and Figure 4 a second embodiment of a guide bearing, and Figure 5 a detailed view of the guide bearing according to Figure 5 , and Figure 6 a detailed view of one side of a guide bearing facing away from the contact surface, and Figure 7 a detailed view of a guide bearing with spring part.

[0040] In the following figures, components with the same function are provided with the same reference symbols.

[0041] The Figure 1Figure 1 shows an embodiment of a vacuum switching device 1 according to the invention, comprising a metallic cover 5 to which a fixed contact 2 is attached inside the vacuum switching device 1. The cover 5 abuts a ceramic insulating body 6 made of aluminum oxide. The insulating body 6, in turn, is connected to a metallic flange 10. The cover 5, the ceramic insulating body 6, and the flange 10 form a fluid-tight housing for the vacuum switching device 1. In the illustrated switched-on state of the switching device 1, a movable contact 3 touches the fixed contact 2. The movable contact 3 is fixedly connected at its attachment point 8 to a metallic bellows 7. The metallic bellows 7 connects fluid-tightly at its other end to the flange 10. The interior of the housing is evacuated, so that the area 4, in which the contacts 2 and 3 touch or come close to each other, can be kept evacuated.

[0042] The movable contact 3 can be pulled away from the fixed contact 2 to disconnect the conductive connection. To enable this, the movable contact is slidably mounted in a guide bearing 9. The guide bearing 9 has a step 14 on which the flange 10 rests. The guide bearing 9 forms a contact surface 12 with the flange 10, which is provided with an adhesive layer 11. A rear surface 35 of the guide bearing is formed on the side facing away from the adhesive layer.

[0043] The Figure 2Figure 1 shows a first embodiment of a guide bearing 20. The guide bearing 20 has a hollow cylinder-like opening 21 for receiving the movable contact. In a stabilizing area 22, the diameter of the hollow cylinder tapers towards the fixed contact. A bonding area 23 is connected to the stabilizing area 22 and is designed to form an adhesive bond with the flange. For this purpose, the bonding area 23 has a contact surface 12 that is formed in a ring-like shape circumferentially in the direction of rotation 38. Wave-like projections 24 are arranged on the contact surface 12. The wave-like projections 24 enable a particularly good and stable adhesive bond to the flange when an adhesive layer is applied to the wave-like profile 24 during the manufacturing process. The contact surface 12 has several bonding openings 25 through which excess adhesive can be forced during the manufacturing process.It can reach the back side 35 (not shown) and form a rivet- or mushroom-shaped structure. This further increases the mechanical stability of the adhesive bond. The step 14 has several anti-slip features 40, which are designed as small and relatively thin ribs. The ribs 40 enable a further improved torsional and slip resistance of the connection when the flange 10 is pressed onto the step 14 or the ribs 40.

[0044] Several flow openings 26 are provided to allow fluid exchange with the environment during switching. The non-evacuated area between the bellows, guide bearing, and moving contact is thus connected to the environment.

[0045] Depending on the design and application of the vacuum switching device, a gas such as air or an electrical insulating gas such as sulfur hexafluoride or dried compressed air can be exchanged with the environment. For certain applications, insulating oil or similar substances can also be discharged through the flow openings. A boundary wall 27 is provided at the outer edge of the contact surface 12, which extends at least as high above the contact surface 12 as the projections 24. It thus forms a barrier, preventing excess adhesive from being smeared outwards.

[0046] Two recesses 28, 29 are provided to collect excess adhesive. These recesses are designed as circumferential grooves and encompass the wave-shaped profiled area 24 on both sides.

[0047] The Figure 3 shows a detailed view of the Figure 2, in particular a barrier wall 32 for the flow opening 26 is discernible. The barrier wall 32 is arranged on the side of the contact surface 12 facing the movable contact and extends at least as high above the contact surface 12 as the projections 24. Thus, the barrier wall 32 shields the flow opening from excess adhesive and therefore ensures that excess adhesive cannot block the flow openings 26 during the manufacture of the vacuum switching device.

[0048] The Figure 4 shows a guide bearing 30, in which a different type of protrusion is used compared to the Figure 2 was chosen. These are cuboid elements pointing radially outwards. These cuboid projections 31 also provide very good slip resistance for the adhesive layer.

[0049] The Figure 5 shows a detailed view of the Figure 4 .

[0050] The Figure 6 shows a detailed view of one side of a guide bearing facing away from the contact surface, or a back side 35 according to Figure 1 The flow openings 26 and the bonding openings 25 are visible. The bonding openings 25 and the flow openings 26 open into recesses 36 on the reverse side 35.

[0051] Guide elements 50 and 51 are also visible; these serve to guide a complementarily shaped movable contact 3 in a rotationally secure manner. Guide element 50 is a projection with a rectangular cross-section, while guide element 51 is designed as a flattened area compared to the circular path.

[0052] The Figure 7Figure 1 shows a detailed view of a guide bearing 9 with a spring element 13. The guide bearing 9 has a stabilizing element 41 that tapers towards the fixed contact. A spring element 13, which can be bent radially inwards in the direction 42, is arranged on this stabilizing element. In the assembled state shown, the spring element 13 provides a clamping fit for the flange 10 on the contact surface 12 of the guide bearing 9 and / or on an inner surface of the bellows 7. This additional locking mechanism, in conjunction with the adhesive layer 11, further increases the mechanical strength.

Claims

1. Vacuum switch device (1) having a housing (5, 6, 10), at one end of which a fixed contact (2) is arranged, and a folding bellows (7), which is fastened on one side to a flange (10) at the other end of the housing (5, 6, 10) and on the other side to a moving contact (3), and a guide bearing (9, 20, 30) for the moving contact (3), which guide bearing is fastened to the flange (10) and guides the moving contact (3) such that it can be displaced in a sliding manner, wherein the guide bearing (9, 20, 30) is secured on the flange (10) with an adhesive layer (11), characterized in that the guide bearing (9, 20, 30) has cutouts (25, 28, 29) arranged on the contact surface (12) and intended to receive excess adhesive.

2. Vacuum switch device (1) according to Claim 1, characterized in that the guide bearing (9, 20, 30) has, on its side facing the flange (10), a roughened contact surface (24).

3. Vacuum switch device (1) according to Claim 2, characterized in that the contact surface (12) has projections (24, 31).

4. Vacuum switch device (1) according to Claim 3, characterized in that the projections (24, 31) are arranged at least partially transversely with respect to the circumferential direction (38) of the contact surface (12).

5. Vacuum switch device (1) according to Claim 3 or 4, characterized in that the projections (24, 31) are at least partially corrugated (24) in form.

6. Vacuum switch device (1) according to either of Claims 3 and 4, characterized in that the projections (24, 31) are at least partially cuboidal (31) in form.

7. Vacuum switch device (1) according to one of Claims 3 to 6, characterized in that the flange (10) has, on its side facing the guide bearing (9, 24, 31), depressions which are formed in a complementary manner to the projections (24, 31) on the guide bearing (9, 20, 30).

8. Vacuum switch device (1) according to Claim 7, characterized in that the cutouts (25, 28, 29) are formed as at least one annularly encircling groove (28, 29).

9. Vacuum switch device (1) according to one of Claims 3 to 8, characterized in that the guide bearing (9, 20, 30) has, at the outer edge of the contact surface (12), a boundary wall (27) which protrudes at least just as high beyond the contact surface (12) as the projections (24, 31), and in that at least one barrier wall (32) is arranged on that side of the contact surface (12) facing the moving contact (3) and protrudes at least just as high beyond the contact surface (12) as the projections (24, 31), wherein the barrier wall (32) encloses a throughflow opening (32) for a fluid, and wherein the throughflow opening (32) is arranged between the guide bearing (9, 20, 30) and the moving contact (3).

10. Vacuum switch device (1) according to one of Claims 2 to 9, characterized in that the contact surface (12) has at least one adhesive opening (25) for receiving adhesive.

11. Vacuum switch device (1) according to one of the preceding claims, characterized in that the guide bearing (9, 20, 30) has a stabilizing part (41) which tapers in the direction of the fixed contact (2) and on which is arranged a radially inwardly bendable spring part (13) which, in the mounted state, provides a clamping seat of the flange (10) on the contact surface (12) of the guide bearing (9, 20, 30) and / or on an inner side of the spring bellows (7).

12. Method for producing a vacuum switch device (1), comprising the steps of: providing a housing (5, 6, 10), at one end of which a fixed contact (2) is arranged, and providing a folding bellows (7), which is fastened on one side to a flange (10) at the other end of the housing (5, 6, 10) and on the other side to a moving contact (3), and pressing a guide bearing (9, 20, 31) for the moving contact (3) onto the flange (10), wherein the guide bearing (9, 20, 31) guides the moving contact (3) such that it can be displaced in a sliding manner, and applying an adhesive layer (11) to the guide bearing (9, 20, 31) and / or the flange (10), characterized by the step of: receiving excess adhesive in cutouts (25, 28, 29) arranged on the contact surface of the guide bearing (9, 20, 30).

13. Production method according to Claim 12, characterized in that a contact surface (12) having projections (24, 31) that is arranged on the side facing the flange (10) is used for the guide bearing (9, 20, 31).

14. Production method according to Claim 13, characterized in that the guide bearing (9, 20, 31) is pushed along the moving contact (3) in the direction of the fixed contact (2) by way of a stabilizing part (41) which tapers in the direction of the fixed contact (2), wherein a radially inwardly bendable spring part (13) is bent inward by the flange (10) until the contact surface (12) is pressed on the flange (10), whereupon the spring part (13) snaps back radially outward and provides a clamping seat of the flange (10) on the contact surface (12) of the guide bearing (9, 20, 31) and / or on an inner side of the spring bellows (13).

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