Vacuum switching device and manufacturing process for a vacuum switching device

Abstract

Vacuum switching device (1), comprising A housing (5,6,10) at one end of which a fixed contact (2) is arranged, and a bellows (7) which is attached on one side to a flange (10) at the other end of the housing (5,6,10) and on the other side to a movable contact (3), and a guide bearing (9, 20, 30) for the movable contact (3), which is attached to the flange (10) and guides the movable contact (3) in a sliding manner, wherein the guide bearing (9, 20, 30) is fixed to the flange (10) with an adhesive layer (11), characterized by the fact that the guide bearing (9,20,30) has a roughened contact surface (24) with projections (24,31) on its side facing the flange (10), which are at least partially cuboid in shape (31).

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 10.

[0002] The operating instructions "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, describe a medium-voltage switching device that features a vacuum switching device with an electromagnetic actuator. The magnetic actuator 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 for pressing a movable contact against a fixed contact within the vacuum switching device. The movable contact is guided out of the vacuum via a flexible bellows.

[0003] A vacuum switching device with a stored-energy spring mechanism 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 the interior of which there is a vacuum (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 at a metallic flange. If a movable contact is quickly pulled away from the fixed contact, e.g., by a spring force, any resulting arc is quickly extinguished. Typically, the current is interrupted temporally in the region of the zero crossing.

[0005] Vacuum switching devices are particularly well suited for switching alternating current because an arc always breaks when the current passes zero. The movable contact is guided out of the vacuum via 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] Until now, the guide bearing was often attached using a separate part, a bearing cap. The bearing cap is soldered to the flange of the moving contact during the soldering process and serves as a holder for the bearing. After inserting the plastic bearing, the upper edge of the bearing cap is folded over to secure the bearing. Solutions are also known in which a type of nozzle is pulled out of the flange, which serves to secure the bearing. Bearings that snap into a locked position during assembly are also known. For this purpose, the plastic bearing is designed to contain locking hooks that can snap into the flange opening. This construction is generally less mechanically stable than the first solution mentioned.

[0007] Furthermore, a vacuum switching device of this type is known from the document JP H06-309 998 A.

[0008] Based on previous vacuum switching devices, the object of the invention is to provide a vacuum switching device that is comparatively simple and cost-effective to manufacture and enables a long operating time.

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

[0010] The housing, for example, has a metal flange as the "cover" and another metal flange as the "base," 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 with a wave-like, accordion-like shape that can be compressed and released with little mechanical resistance, while simultaneously being fluid-tight and durable. A bellows is made, for example, from a thin sheet of metal.

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

[0013] An adhesive layer within the meaning of the invention is a layer less than 5 mm thick containing an adhesive that cures after application and provides high mechanical strength against tearing when switching the vacuum switching device on and off, as well as against twisting and bending 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 movable contact through the housing. The movable contact is typically designed like a bolt, 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, the guide bearing is often made of plastic and formed, for example, by injection molding or machining. In such a case, the adhesive layer connects 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. There is no need to secure the plastic guide bearing to the flange with a sheet metal that is bent radially inward for fixation. This enables faster and more cost-effective production. Furthermore, a significant advantage is that, compared to previous designs, the anti-rotation device between the rod and the bearing or a bearing support can be aligned following a soldering process to produce the fluid-tight housing. Another advantage is that the surface 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.

[0016] In a further development of the vacuum switching device, additional mechanical stabilization can be achieved by a mechanical locking device pressing the guide bearing and the flange together and / or preventing the components from being pulled apart. This relieves the adhesive bond and ensures mechanical stability, for example, even in cases where the adhesive layer could be loosened by heating during operation of the vacuum switching device as a result of a current flow. The mechanical locking device can, for example, be designed as a so-called snap nose. This is a spring device that is fixed at one of its two ends to a cylindrical stabilization area of ​​the guide bearing and projects from this in the longitudinal direction (coaxial to the direction in which the movable contact is guided), i.e. towards the contact surface.In this context, protrusion means that there is a hollow space between the spring device and the stabilizing area. This allows the spring device to be pressed against the stabilizing area by exerting pressure from the outside inwards, i.e. towards the stabilizing area. The spring device is dimensioned such 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 device can snap out again, forming the hollow space and locking the flange like a barb. It is particularly preferred to then also fill the hollow space between the spring device and the stabilizing area with the adhesive. Once cured, the locking mechanism can no longer be released.

[0017] Compared to previous solutions, which used a sheet metal for locking, the contact area to the flange is no longer hollow but solid to form a contact surface for the adhesive.

[0018] 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 by the invention, is defined as an electrical voltage of up to 1 kV.

[0019] 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 by the invention, is characterized by an electrical voltage between 1 kV and 52 kV.

[0020] 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 by the invention, is defined as an electrical voltage above 52 kV.

[0021] The guide bearing has a roughened contact surface on its side facing the flange. Roughened, as defined in the invention, means that the surface is no longer smooth. A roughened contact surface has, for example, projections and / or depressions greater 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.

[0022] 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 defined by the invention, means that the surface is no longer smooth. A roughened surface has, for example, projections 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.

[0023] The contact surface has projections. Projections within the meaning of the invention are elevations of any shape relative to the plane of the contact surface, which, for example, are raised by at least one mm. If recesses are provided on the contact surface, all non-recessed areas are considered projections within the meaning of the invention. Projections are advantageous because they provide a particularly roughened surface for the adhesive, thus further increasing the adhesive force.

[0024] If the movable contact is designed as a bolt, the guide bearing can also be designed radially symmetrically. In this case, the contact surface forms, for example, a ring-shaped, circumferential surface.

[0025] 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 guide bearing engaging around the movable contact, i.e. forming 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 multi- or polygonal. Longitudinal to the direction of rotation corresponds to an alignment of the projections with their long side along the circumference around the movable contact, which offers comparatively little resistance to rotational movements in terms of strength during bonding. Longitudinal encompasses, for example, an alignment of 0 ° to + / - 30 ° relative to the direction of rotation.Transverse to the direction of rotation corresponds to an orientation of the projections with their short side along the circumference of the movable contact, which presents their long side during bonding and offers comparatively high resistance to rotational movements. For example, transverse encompasses an orientation of + / - 60° to 90° relative to the direction of rotation.

[0026] 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.

[0027] The projections are at least partially cuboidal. This is an advantage because even 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 flange has recesses on its side facing the guide bearing, which are complementary to the projections on the guide bearing. A complementary surface of the flange offers the advantage that projections and recesses can interlock, which enables particularly strong resistance to torsional forces during switching. The mechanical strength of the adhesive connection is further improved. In a further development, adhesive gaps can advantageously 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.

[0029] In the embodiments explained above, projections are provided on the guide bearing and, if necessary, recesses are provided on the flange. However, it is equally preferable and technically just as easy to implement to provide projections on the flange and, if necessary, recesses on the guide bearing.

[0030] In a further preferred embodiment of the vacuum switching device according to the invention, the guide bearing has recesses arranged on the contact surface for accommodating excess adhesive. This is advantageous because a consistently thick adhesive layer is always formed when the guide bearing is pressed against the flange during production.

[0031] 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.

[0032] In a further preferred embodiment of the vacuum switching device according to the invention, the guide bearing has a boundary wall on the outer edge of the contact surface, which protrudes 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 protrudes 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 a border for the adhesive layer and thus reduce smearing of excess adhesive during production.

[0033] 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 wetting of the inner walls of openings in the contact surface after the adhesive has hardened increases the mechanical load-bearing capacity of the adhesive connection. In the simplest case, the bonding openings are bores. It is particularly preferred if, during production, sufficient adhesive is applied that the adhesive is pressed through the at least one bonding opening onto the rear side (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 outside the opening on the rear side. The adhesive thus forms a rivet-like ormushroom-like shape at the bonding opening, which increases both the torsion resistance and the tear-out strength of the adhesive bond.

[0034] In a further preferred embodiment of the vacuum switching device according to the invention, the guide bearing has a stabilizing part tapering toward the fixed contact, on which a radially inwardly bendable spring part is arranged. When assembled, this spring part provides a clamping fit of the flange against the contact surface of the guide bearing and / or against an inner side of the bellows. This additional locking, in conjunction with the adhesive layer, further increases the mechanical strength.

[0035] 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 connection between the guide bearing and the flange. For example, notches and recesses can be used as locking elements. A bayonet lock can also be formed using the guide bearing and / or the flange. This can further increase mechanical stability, especially under thermal stress.

[0036] Based on previous manufacturing methods for a vacuum switching device, the invention further has the object of specifying a manufacturing method for a vacuum switching device which is comparatively simple and cost-effective and enables a long operating life of the vacuum switching device.

[0037] The invention solves this problem by a vacuum switching device according to claim 10. Preferred embodiments of the manufacturing method according to the invention are explained in the dependent claim 11. This results in the same advantages as initially described for the vacuum switching device according to the invention.

[0038] To better explain the invention, the following schematic representations show Fig. 1 an embodiment of a vacuum switching device according to the invention, and Fig. 2 a first embodiment of a guide bearing, and Fig. 3 a detailed view of the guide bearing according to Fig. 2, and Fig. 4 a second embodiment of a guide bearing, and Fig. 5 a detailed view of the guide bearing according to Fig. 5, and Fig. 6 a detailed view of a side of a guide bearing facing away from the contact surface, and Fig. 7 a detailed view of a guide bearing with spring part.

[0039] In the following figures, components with the same function are provided with the same reference numerals.

[0040] The Fig. 1 shows an exemplary 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 adjoins 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. A movable contact 3 touches the fixed contact 2 in the illustrated switched-on state of the switching device 1. The movable contact 3 is firmly connected to a metallic bellows 7 at the attachment point 8. The metallic bellows 7 adjoins the flange 10 at its other end in a fluid-tight manner. The interior of the housing is evacuated, so that the area 4 in which the contacts 2, 3 touch or come close to each other can be kept evacuated.

[0041] The movable contact 3 can be pulled away from the fixed contact 2 to separate 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 side 35 of the guide bearing is formed on the side facing away from the adhesive layer.

[0042] The Fig. 2 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 region 22, the diameter of the hollow cylinder tapers towards the fixed contact. Connected to the stabilizing region 22 is an attachment region 23, which is provided for forming an adhesive connection with the flange. For this purpose, the attachment region 23 has a contact surface 12 that is annularly configured in the circumferential direction 38. Wave-like projections 24 are arranged on the contact surface 12. The wave-like projections 24 enable a particularly good and stable adhesive connection to the flange if a layer of adhesive is applied to the wave-shaped profile 24 during the manufacturing process. The contact surface 12 has a plurality of bonding openings 25 through which excess adhesive can be forced during the manufacturing process.It can reach the rear side 35 (not shown) and form a rivet-like or mushroom-like shape. 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 comparatively thin webs. The webs 40 enable the connection to achieve further improved torsional and slip resistance when the flange 10 is pressed onto the step 14 or the webs 40.

[0043] Several flow openings 26 are provided, allowing fluid to flow through the environment during switching. The non-evacuated area between the bellows, guide bearing, and moving contact is thus connected to the environment.

[0044] 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 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 represents a barrier, preventing excess adhesive from being smeared outward.

[0045] Two recesses 28, 29 are provided to accommodate excess adhesive. The two recesses 28, 29 are designed as circumferential grooves and enclose the wave-shaped profiled area 24 on both sides.

[0046] The Fig. 3 shows a detailed view of the Fig. 2, wherein, in particular, a barrier wall 32 for the flow opening 26 can be seen. 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 enables shielding of the flow opening from excess adhesive and thus ensures that excess adhesive cannot block the flow openings 26 during the manufacture of the vacuum switching device.

[0047] The Fig. 4 shows a guide bearing 30 in which a different type of projections is used compared to the Fig. 2 was selected. These are cuboid-shaped elements pointing radially outward. These cuboid-shaped projections 31 also provide very good slip resistance for the adhesive layer.

[0048] The Fig. 5 shows a detailed view of the Fig. 4.

[0049] The Fig. 6 shows a detailed view of a side of a guide bearing facing away from the contact surface, or a rear side 35 according to Fig. 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 back 35.

[0050] Also visible are guide means 50, 51, which serve to guide a complementarily shaped movable contact 3 in a rotationally secure manner. The guide means 50 is a projection with a rectangular cross-section, while the guide means 51 is designed as a flattened area relative to the circular path.

[0051] The Fig.Figure 7 shows a detailed view of a guide bearing 9 with a spring part 13. The guide bearing 9 has a stabilizing part 41 tapering in the direction of the fixed contact, on which a spring part 13 is arranged that can be bent radially inward in the direction 42. In the assembled state shown, this spring part provides a clamp fit of the flange 10 on the contact surface 12 of the guide bearing 9 and / or on an inner side of the bellows 7. This additional locking, in conjunction with the adhesive layer 11, further increases the mechanical strength.

Claims

[1] Vacuum switching device (1), comprising A housing (5,6,10), at one end of which a fixed contact (2) is arranged, and a bellows (7) which is attached on the one hand to a flange (10) at the other end of the housing (5, 6, 10) and on the other hand to a movable contact (3), and a guide bearing (9, 20, 30) for the movable contact (3), which is fastened to the flange (10) and guides the movable contact (3) in a sliding manner, wherein the guide bearing (9,20,30) is fixed to the flange (10) with an adhesive layer (11), characterized by , that the guide bearing (9, 20, 30) has, on its side facing the flange (10), a roughened contact surface (24) with projections (24, 31) which are at least partially cuboid-shaped (31). [2] Vacuum switching device (1) according to claim 1, characterized bythat the projections (24,31) are arranged at least partially transversely to the direction of rotation (38) of the contact surface (12). [3] Vacuum switching device (1) according to claim 2, characterized by that the projections (24,31) are at least partially wave-shaped (24). [4] Vacuum switching device (1) according to one of claims 1 to 3, characterized by that the flange (10) has, on its side facing the guide bearing (9,24,31), recesses which are complementary to the projections (24,31) on the guide bearing (9,20,30). [5] Vacuum switching device (1) according to one of the preceding claims, characterized by that the guide bearing (9,20,30) has recesses (25,28,29) arranged on the contact surface (12) for receiving excess adhesive. [6] Vacuum switching device (1) according to claim 5, characterized by that the recesses (25,28,29) are designed as at least one annular circumferential groove (28,29). [7] Vacuum switching device (1) according to one of claims 1 to 6, characterized by that the guide bearing (9, 20, 30) has a boundary wall (27) on the outer edge of the contact surface (12), which projects at least as high above the contact surface (12) as the projections (24, 31), and that at least one barrier wall (32) is arranged on the side of the contact surface (12) facing the movable contact (3), which barrier wall (32) projects at least as high above the contact surface (12) as the projections (24, 31), wherein the barrier wall (32) encloses a flow opening (32) for a fluid, and wherein the flow opening (32) is arranged between the guide bearing (9, 20, 30) and the movable contact (3). [8] Vacuum switching device (1) according to one of the preceding claims, characterized by that the contact surface (12) has at least one bonding opening (25) for receiving adhesive. [9] Vacuum switching device (1) according to one of the preceding claims, characterized by that the guide bearing (9, 20, 30) has a stabilizing part (41) which tapers in the direction of the fixed contact (2), on which a spring part (13) which can be bent radially inwards is arranged and which, in the assembled state, provides a clamping fit of the flange (10) on the contact surface (12) of the guide bearing (9, 20, 30) and / or on an inner side of the bellows (7). [10] Manufacturing method for a vacuum switching device (1), comprising the steps: Providing a housing (5, 6, 10), at one end of which a fixed contact (2) is arranged, and Providing a bellows (7) which is attached on the one hand to a flange (10) at the other end of the housing (5, 6, 10) and on the other hand to a movable contact (3), and Pressing a guide bearing (9, 20, 30) for the movable contact (3) onto the flange (10), wherein the guide bearing (9, 20, 30) guides the movable contact (3) in a sliding manner, and Applying an adhesive layer (11) to the guide bearing (9, 20, 30) and / or the flange (10), characterized by ,that: for the guide bearing (9, 20, 30) a guide bearing is used which has on its side facing the flange (10) a roughened contact surface (24) with projections (24, 31) which are at least partially cuboid-shaped (31). [11] Manufacturing method according to claim 10 characterized bythat the guide bearing (9, 20, 30) with a stabilizing part (41) tapering in the direction of the fixed contact (2) is pushed along the movable contact (3) in the direction of the fixed contact (2), wherein a radially inwardly bendable spring part (13) is bent inwards by the flange (10) until the contact surface (12) is pressed against the flange (10), whereupon the spring part (13) snaps back radially outwards and provides a clamping fit of the flange (10) on the contact surface (12) of the guide bearing (9, 20, 30) and / or on an inner side of the bellows (13).

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