SWITCHING DEVICE

Abstract

Switching device (100) comprising at least one fixed contact (2, 3) and at least one movable contact (4), wherein at least one of the contacts (2, 3, 4) comprises a metal matrix composite material with a metallic matrix material and a filler dispersed in the matrix material, wherein the contacts (2, 3, 4) are arranged in a switching chamber (11) with a gas (14), and the gas H 2 contains and wherein the at least one movable contact (4) is formed entirely from the metal matrix composite material.

Description

[0001] A switching device is specified.

[0002] The switching device is designed, in particular, as an electromagnetically acting, remotely operated switch operable by an electrically conductive current. The switching device can be activated via a control circuit and can switch a load circuit. In particular, the switching device can be designed as a relay or as a contactor, in particular as a power contactor. Particularly preferably, the switching device can be designed as a gas-filled power contactor.

[0003] One possible application for such switching devices, in particular power contactors, is the opening and disconnecting of battery circuits, for example in motor vehicles such as electric or partially electric vehicles. These can be, for example, purely battery-powered vehicles (BEV: "Battery Electric Vehicle"), hybrid electric vehicles that can be charged via a socket or charging station (PHEV: "Plug-in Hybrid Electric Vehicle"), and hybrid electric vehicles (HEV: "Hybrid Electric Vehicle"). In this case, both the positive and negative contacts of the battery are usually disconnected using a power contactor. This disconnection occurs during normal operation, for example when the vehicle is at rest, as well as in the event of a malfunction such as an accident or similar. The main task of the power contactor is to de-energize the vehicle and interrupt the flow of current.

[0004] A particularly serious fault that can occur with such a switch is a so-called "stuck" condition. In this case, switching elements "stick" together due to welding during a disconnection or connection, so that even though the switch's supply voltage has been disconnected, reliable isolation of the load circuit cannot be guaranteed.

[0005] DE 34 30 490 C2 describes a contactor in which the use of tungsten or molybdenum in copper improves the erosion properties and reduces the tendency to weld. However, these materials are complex and expensive to manufacture and result in increased contact resistance when the switch is closed, which is generally undesirable in high-current applications, for example.

[0006] In open contactors, silver alloys and silver metal oxide alloys, such as AgCdO or AgSnO, are used to reduce the tendency to weld. However, due to the unstable oxide content, these compounds are unsuitable in a hydrogen-containing atmosphere, such as that used in gas-filled power contactors, as this would cause the oxide to react with the hydrogen.

[0007] US Pat. No. 5,519,370 A describes a relay that can be gas-filled, and which can contain hydrogen as the gas. The relay has fixed contacts made of a dispersion-reinforced copper-aluminum oxide material.

[0008] The publication DE 694 14 902 T2 describes oxide dispersion strengthened alloys for use in resistance electrodes, sliding contact components and electrical contacts.

[0009] The document DE 10 2012 112 202 A1 describes a switching device with a hydrogen-containing gas filling.

[0010] At least one object of certain embodiments is to provide a switching device, particularly preferably a switching device, in which the tendency to welding can be avoided or at least reduced.

[0011] This object is achieved by a subject matter according to the independent patent claim. Advantageous embodiments and developments of the subject matter are characterized in the dependent claims and will further become apparent from the following description and the drawings.

[0012] According to one embodiment, a switching device has at least one fixed contact and at least one movable contact. The at least one fixed contact and the at least one movable contact are provided and configured to switch a load circuit connectable to the switching device on and off. The movable contact is movable in the switching device between a non-switching state and a switching state of the switching device in such a way that the movable contact is spaced from the at least one fixed contact in the non-switching state of the switching device and is thus galvanically isolated, and in the switching state has a mechanical contact with the at least one fixed contact and is thus galvanically connected to the at least one fixed contact.Particularly preferably, the switching device has at least two fixed contacts which are arranged separately from one another in the switching device and which can thus be electrically connected to one another or electrically separated from one another by the movable contact, depending on the state of the movable contact.

[0013] According to a further embodiment, the switching device has a housing in which the movable contact and the at least one fixed contact or the at least two fixed contacts are arranged. The movable contact can in particular be arranged entirely in the housing. The fact that a fixed contact is arranged in the housing can in particular mean that the contact region of the fixed contact, which is in mechanical contact with the movable contact in the switched-on state, is arranged within the housing. In order to connect a supply line of an electrical circuit to be switched by the switching device, a fixed contact arranged in the housing can be electrically contactable from the outside, i.e. from outside the housing. For this purpose, a fixed contact arranged in the housing can protrude part of the housing and have a connection option for a supply line outside the housing.

[0014] According to a further embodiment, the contacts are arranged in a gas atmosphere in the housing. This can mean, in particular, that the movable contact is arranged entirely in the gas atmosphere in the housing and that, furthermore, at least parts of the fixed contact(s), for example the contact region(s) of the fixed contact(s), are arranged in the gas atmosphere in the housing. The switching device can accordingly particularly preferably be a gas-filled switching device such as a gas-filled contactor. In particular, the contacts, i.e. the movable contact entirely and at least parts of the fixed contact(s), can be arranged in a switching chamber within the housing in which the gas, i.e. at least part of the gas atmosphere, is located. The gas can preferably have a proportion of at least 50% H 2 In addition to the H 2 the gas may comprise an inert gas, particularly preferably N2 and / or one or more noble gases.

[0015] Furthermore, at least one of the contacts comprises a metal matrix composite material with a metallic matrix material and a filler dispersed in the matrix material. The metal matrix composite material can particularly preferably comprise copper or a copper alloy as the matrix material. Such materials can advantageously have high electrical conductivity and correspondingly a high current-carrying capacity. The filler can particularly preferably comprise a metal oxide, in particular a high-melting, very stable metal oxide. For example, the filler can comprise an oxide with aluminum. Alternatively or in addition to aluminum oxide, the filler can also comprise at least one or more other ceramic oxides.

[0016] According to a further embodiment, the filler is formed by particles that can preferably be uniformly and homogeneously distributed in the matrix material. It has proven advantageous if the particles have an average size of less than 1 µm and preferably less than 0.1 µm, so that the filler particularly preferably has a uniform, fine-crystalline distribution in the matrix material. Such a fine-crystalline distribution can be achieved, for example, by adding an oxidizing agent to a powder made of an alloy with the matrix material and with the metal on which the filler is based, whereby the metal on which the filler is based and contained in the powder particles is oxidized. The desired components can then be manufactured, for example, by pressing and sintering the matrix material-oxide composite powder produced in this way.

[0017] According to a further embodiment, the proportion of filler in the matrix material is less than or equal to 2%, wherein the proportion can be measured in particular in wt. It has proven advantageous if the proportion of filler in the matrix material is less than or equal to 1% or even less than or equal to 0.3%. Furthermore, the proportion of filler in the matrix material can be greater than or equal to 0.2%.

[0018] It has been shown that the addition of the filler to the matrix material, which can improve the mechanical properties of the matrix material, particularly under high temperature loads, also results in a very low welding tendency when used, particularly in switching devices filled with hydrogen-containing gas. Thus, the problem of the welding tendency of contacts in the switching device described here, which is particularly preferably a switching device filled with hydrogen-containing gas, can be reduced or even completely solved by the metal matrix composite material described here by adding a small amount of a high-melting, very stable metal oxide to a metal material, preferably a copper material, for one or more of the contacts.The preferably fine distribution of the particulate filler can, in particular, increase the mechanical strength of the metallic matrix material without compromising its thermal or electrical conductivity. In particular, tests with the switching device described here have shown that the metal matrix composite material can achieve more switching operations at a switching current of more than 100 A without "sticking," i.e., without welding the contacts, than when using conventional contact materials that do not correspond to the metal matrix composite material described here.

[0019] According to the invention, at least the movable contact is formed entirely from the metal matrix composite material. In addition, the at least one fixed contact can also comprise the metal matrix composite material or be formed entirely from it. If the switching device has at least two fixed contacts, preferably all fixed contacts of the switching device can comprise the metal matrix composite material or can each be formed entirely from it. It can be particularly preferred if all contacts, i.e., all fixed and movable contacts of the switching device, comprise the metal matrix composite material or can each be formed entirely from it.

[0020] If a contact comprises the metal matrix composite material, this can also mean that the contact has a contact body and at least one contact region attached to the contact body, and the at least one contact region comprises the metal matrix composite material. The contact body can be made of a metal material, for example the metallic matrix material, for example copper or a copper alloy, without embedded filler. The contact region can be formed, for example, as a platelet, for example with a thickness of 1 mm or less and typically with a thickness of about 0.5 mm, and can be attached to the contact body. For example, a contact region, for example a contact platelet, can be attached to the contact body by brazing, riveting, caulking or another suitable method. Particularly preferably, all contacts can also have corresponding contact bodies and contact regions.Furthermore, it may also be possible for the movable contact, for example, to be formed entirely from the metal matrix composite material, while the fixed contact(s) is / are each formed by a contact body with a contact region arranged thereon, formed from the metal matrix composite material. A reverse design is also possible.

[0021] Further advantages, advantageous embodiments and further developments emerge from the exemplary embodiments described below in conjunction with the figures.

[0022] They show: Fig. 1A and Fig. 1B schematic representations of a switching device according to an embodiment and Fig. 2A and Fig. 2B schematic representations of parts of contacts of switching devices according to further embodiments.

[0023] In the exemplary embodiments and figures, identical, similar, or similarly functioning elements may be provided with the same reference numerals. The illustrated elements and their relative sizes are not to be considered to scale; rather, individual elements, such as layers, components, structural elements, and regions, may be exaggerated for clarity and / or clarity.

[0024] In the Fig. 1A and Fig. 1B shows an embodiment of a switching device 100, which can be used, for example, to switch strong electrical currents and / or high electrical voltages and which can be a relay or contactor, in particular a power contactor. In Fig. 1A shows a three-dimensional sectional view, while in Fig. 1B shows a two-dimensional sectional view. The following description also applies to the Fig. 1A and Fig. 1B. The geometries shown are only exemplary and not limiting and can also be designed alternatively.

[0025] The switching device 100 comprises two fixed contacts 2, 3 and one movable contact 4 in a housing 1. The movable contact 4 is designed as a contact plate. The fixed contacts 2, 3, together with the movable contact 4, form the switching contacts. The housing 1 primarily serves as contact protection for the components arranged inside and comprises or is made of a plastic, for example, polybutylene terephthalate (PBT) or glass-filled PBT.

[0026] In the Fig. 1A and Fig. 1B shows the switching device 100 in a rest state, in which the movable contact 4 is spaced apart from the stationary contacts 2, 3, so that the contacts 2, 3, 4 are galvanically isolated from one another. The illustrated design of the switching contacts, and in particular their geometry, are purely exemplary and not to be understood as limiting. Alternatively, the switching contacts can also be designed differently. For example, it may be possible for only one of the switching contacts to be stationary.

[0027] The switching device 100 has a movable magnetic armature 5, which essentially performs the switching movement. The magnetic armature 5 has a magnetic core 6, for example, made of or made of a ferromagnetic material. Furthermore, the magnetic armature 5 has a shaft 7, which is guided through the magnetic core 6 and is firmly connected to the magnetic core 6 at one end of the shaft. At the other end of the shaft, opposite the magnetic core 6, the magnetic armature 5 has the movable contact 4, which is also connected to the shaft 7. The shaft 7 can, for example, be made of or made of stainless steel.

[0028] The magnetic core 6 is surrounded by a coil 8. A current flow in the coil 8, which can be switched on from the outside, generates a movement of the magnetic core 6 and thus of the entire magnetic armature 5 in the axial direction until the movable contact 4 contacts the fixed contacts 2, 3. The magnetic armature 5 thus moves from a first position, which corresponds to the rest state and simultaneously the isolating, i.e. non-switching, state, to a second position, which corresponds to the active, i.e. switching, state. In the active state, the contacts 2, 3, 4 are galvanically connected to one another. In another embodiment, the magnetic armature 5 can alternatively also execute a rotary movement. The magnetic armature 5 can in particular be designed as a tension rod or a hinged armature.To guide the shaft 7 and thus the magnet armature 5, the switching device 100 has a yoke 9, which may be made of pure iron or a lightly doped iron alloy and forms part of the magnetic circuit. The yoke 9 has an opening through which the shaft 7 is guided. If the current flow in the coil 8 is interrupted, the magnet armature 5 is moved back to the first position by one or more springs 10. The switching device 100 is then in the rest state again, in which the contacts 2, 3, 4 are open.

[0029] When contacts 2, 3, 4 are opened, an arc may occur that can damage the contact surfaces. This can lead to the risk that contacts 2, 3, 4 will "stick" to one another due to welding caused by the arc and can no longer be separated. To prevent the formation of such arcs or at least to assist in the extinguishing of arcs that do occur, contacts 2, 3, 4 are arranged in a gas atmosphere, so that switching device 100 is designed as a gas-filled relay or gas-filled contactor. Secondly, at least one of contacts 2, 3, 4 comprises a material that shows little or no tendency to weld.

[0030] With regard to the gas atmosphere, the contacts 2, 3, 4 are arranged within a switching chamber 11, formed by a switching chamber wall 12 and a switching chamber base 13, in a hermetically sealed part of the housing 1. The housing 1, and in particular the hermetically sealed part of the housing 1, completely surrounds the magnet armature 5 and the contacts 2, 3, 4. The hermetically sealed part of the housing 1 and thus also the switching chamber 11 are filled with a gas 14. The gas 14, which can be filled through a gas filling nozzle 15 during the manufacture of the switching device 100, can particularly preferably contain hydrogen, particularly preferably with 50% or more H 2 in an inert gas or even with 100% H 2 , since hydrogen-containing gas can promote the extinguishing of arcs. If the proportion of H 2on the gas 14 is less than 100%, the gas may additionally comprise one or more inert gases, in particular selected from N 2 and noble gases. Furthermore, so-called blowout magnets (not shown) can be present inside or outside the switching chamber 11. These permanent magnets can lengthen the arc gap and thus improve arc extinguishing. The switching chamber wall 12 and the switching chamber floor 13 can be coated, for example, with or from a metal oxide such as Al 2 O 3 be manufactured.

[0031] At least the fixed contact 4 is formed entirely from a metal matrix composite material comprising a metallic matrix material and a filler dispersed in the matrix material. The metal matrix composite material can particularly preferably comprise copper or a copper alloy as the matrix material, so that the metal matrix composite material can have high electrical conductivity and correspondingly high current-carrying capacity.

[0032] The filler comprises a metal oxide or is formed by a metal oxide. Particular preference is given to using a high-melting, very stable metal oxide, for example aluminum oxide or a mixture of ceramic oxides with aluminum oxide. As an alternative to aluminum oxide, the filler can also comprise at least one or more other ceramic oxides. The filler is dispersed in the matrix material in the form of particles. Particular preference is given to uniformly and homogeneously distributing the filler in the matrix material, with the particles having an average size of less than 1 µm and preferably less than 0.1 µm. It has been shown that the proportion of filler in the matrix material is preferably less than or equal to 2 wt.%. Particular preference is given to the proportion of filler in the matrix material being less than or equal to 1 wt.% or even less than or equal to 0.3 wt.% and greater than or equal to 0.2 wt.%.

[0033] By adding the filler to the metallic matrix material, a metal matrix composite material can be formed that exhibits increased mechanical strength compared to the pure matrix material while maintaining the same or essentially the same thermal and electrical conductivity. Surprisingly, the metal matrix composite material also exhibits a very low welding tendency, especially in hydrogen-filled switching devices.

[0034] Particularly preferably, all contacts 2, 3, 4, i.e., all fixed and movable contacts of the switching device 100, can comprise the metal matrix composite material or even be formed entirely from it. This allows the advantageous effect of the metal matrix composite material to be achieved for all contacts 2, 3, 4.

[0035] However, it may also be possible for only one of the contacts, i.e., at least the movable contact 4, to comprise and be formed from the metal matrix composite material. In this case, the fixed contacts 2, 3 may comprise or be made from a conventional contact material, for example, Cu, a Cu alloy, or a mixture of copper with at least one other metal, for example, Wo, Ni, and / or Cr. Furthermore, at least one or all of the fixed contacts 2, 3 may comprise the metal matrix composite material or, preferably, may each be formed entirely from it.

[0036] As an alternative to a complete formation of one or more fixed contacts 2, 3 from the metal matrix composite material, the contact(s) may, for example, comprise the metal matrix composite material only in one contact area. The contact area is applied to a contact body formed from a conventional contact material. The contact area of ​​a contact is the area with which the contact touches the other contact intended for the switching operation in the active state of the switching device. Fig. 2A shows a detail of a non-inventive example of a movable contact 4 with a contact body 40 made of a conventional contact material and a contact area 41 made of the metal matrix composite material, while in Fig. 2B shows a detail of an embodiment of a corresponding fixed contact 2 with a contact body 20 made of a conventional contact material and a contact region 21 made of the metal matrix composite material.

[0037] The contact areas 21, 41 can each be formed as small plates, for example with a typical thickness of approximately 0.5 mm, and can be attached to the respective contact body 20, 40, for example by brazing, riveting, or caulking. It may be possible, for example, for the fixed contacts to be formed according to the embodiment of the Fig. 2B, while the movable contact is formed from the metal matrix composite material. A non-inventive embodiment consists in the design of the movable contact 4 according to the embodiment of Fig.2A, while the fixed contacts 2, 3 are formed from a conventional contact material or, more preferably, from the metal matrix composite material.

[0038] The features and exemplary embodiments described in conjunction with the figures can be combined with one another according to further exemplary embodiments, even if not all combinations are explicitly described. Furthermore, the exemplary embodiments described in conjunction with the figures can alternatively or additionally have further features according to the description in the general part. List of reference symbols 1 housing 2, 3 fixed contact 4 movable contact 5 magnet armature 6 magnetic core 7 axis 8 coil 9 yoke 10 springs 11 Switching chamber 12 Switching chamber wall 13 Switching chamber base 14 Gas 15 gas filling nozzles 20, 40 contact bodies 21, 41 Contact area 100 switching device

Claims

[1] Switching device (100) comprising at least one fixed contact (2, 3) and at least one movable contact (4), wherein at least one of the contacts (2, 3, 4) comprises a metal matrix composite material with a metallic matrix material and a filler dispersed in the matrix material, wherein the contacts (2, 3, 4) are arranged in a switching chamber (11) with a gas (14) and the gas contains H2 and wherein the at least one movable contact (4) is formed entirely from the metal matrix composite material. [2] Switching device (100) according to the preceding claim, wherein the at least one fixed contact (2, 3) comprises the metal matrix composite material. [3] Switching device (100) according to the preceding claim, wherein the switching device (100) has at least two fixed contacts (2, 3) and all fixed contacts (2, 3) comprise the metal matrix composite material. [4] Switching device (100) according to one of the preceding claims, wherein all fixed and movable contacts (2, 3, 4) of the switching device (100) comprise the metal matrix composite material. [5] Switching device (100) according to one of the preceding claims, wherein at least one of the fixed contacts (2, 3) is formed entirely from the metal matrix composite material. [6] Switching device (100) according to one of the preceding claims, wherein all fixed and movable contacts (2, 3, 4) of the switching device (2, 3, 4) are formed entirely from the metal matrix composite material. [7] Switching device (100) according to one of claims 1 to 5, wherein at least one of the fixed contacts (2, 3) comprises a contact body (20) and at least one contact region (21) attached to the contact body (20), and the at least one contact region (21) comprises the metal matrix composite material. [8] Switching device (100) according to one of the preceding claims, wherein the metal matrix composite material comprises copper or a copper alloy as the matrix material. [9] Switching device (100) according to one of the preceding claims, wherein the filler comprises a metal oxide. [10] Switching device (100) according to the preceding claim, wherein the filler comprises an oxide with aluminum. [11] Switching device (100) according to one of the preceding claims, wherein the filler is formed by particles. [12] Switching device (100) according to the preceding claim; wherein the particles have an average size of less than 1 µm. [13] Switching device (100) according to one of the two preceding claims, wherein the particles have an average size of less than or equal to 0.1 µm. [14] Switching device (100) according to one of the preceding claims, wherein the proportion of the filler in the matrix material is less than or equal to 2%. [15] Switching device (100) according to one of the preceding claims, wherein the proportion of the filler in the matrix material is less than or equal to 1%. [16] Switching device (100) according to one of the preceding claims, wherein the proportion of the filler in the matrix material is less than or equal to 0.3%. [17] Switching device (100) according to one of the preceding claims, wherein the proportion of filler in the matrix material is greater than or equal to 0.2%. [18] Switching device (100) according to one of the preceding claims, wherein the gas has a proportion of at least 50% H2.

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