Method and device for producing a magnetic-flux-guiding element for an electrical device, and such an electrical device

Abstract

The invention relates to a method for producing at least one magnetic-flux-guiding element (2) for an electrical device, having the following steps: - providing a casting mold (1.1) having a fillable cavity (1.2), - filling the cavity with a soft magnetic powder material (2.1) or a powder-binder mixture, - evacuating the filled cavity, and - shaping the magnetic-flux-guiding element (2) in the cavity (2.1). The invention further relates to a device for producing the magnetic-flux-guiding element (2) and to an electrical device having such a magnetic-flux-guiding element (2).

Description

[0001] 2024PF00389 Foreign version

[0002] 1

[0003] Description

[0004] Method and apparatus for manufacturing a magnetic flux guide element for an electrical device, and such an electrical device

[0005] The invention relates to a method and a device for manufacturing a magnetic flux guide element for an electrical device, as well as to an electrical device manufactured in this way.

[0006] Electrical devices, especially high-voltage components such as transformers or chokes for high-voltage networks, typically incorporate electrical steel sheets to guide magnetic fluxes. Care is taken to ensure that the pulsating magnetic flux is guided in the rolling direction of the electrical steel sheets, as electromagnetic losses are lowest in this direction.

[0007] Due to complex flux distributions near current-carrying high-voltage lines or windings, electrical steel cannot be used in these areas, as the impact of the magnetic flux normal to the sheet surface induces high eddy currents in the electrical steel sheets and consequently generates high electrical losses and temperatures in the electrical steel sheets.

[0008] The invention is based on the objective of providing a simple method and a simple apparatus for manufacturing at least one magnetic flux guide element for an electrical device, as well as an electrical device with a magnetic flux guide element that is easy to manufacture and exhibits low losses. According to the invention, a method for manufacturing at least one magnetic flux guide element for an electrical device is proposed. The method comprises the following steps: 2024PF00389 Foreign version

[0009] 2

[0010] - Providing a mold with a fillable cavity,

[0011] - Filling the cavity with a soft magnetic powder material or a powder-binder mixture,

[0012] - Evacuating the filled cavity, and

[0013] - Shaping the magnetic flux guide element in the cavity.

[0014] The shape of the mold cavity corresponds to the shape of the flux guide element to be produced. In other words, the magnetic flux guide element is cast using the mold and formed as a single casting with a 3D structure. Complex geometries can be easily manufactured using such a 3D-cast magnetic flux guide element. Furthermore, such a magnetic flux guide element made from a soft magnetic powder material or powder-binder mixture reduces or even eliminates electrical losses, particularly eddy current losses, and temperature increases.

[0015] The procedure may include the following further steps:

[0016] - Airtight sealing of the mold with the filled cavity,

[0017] - Evacuating the filled cavity, and

[0018] - Filling the vacuum areas formed in the cavity as a result of evacuation with a binding agent.

[0019] Preferably, the airless spaces formed between powder particles after evacuation are filled with the binder. The binder can then bind the powder particles together. If a powder-binder mixture is filled into the mold, subsequent filling with a binder is not necessary, but possible. 2024PF00389 Foreign version

[0020] 3

[0021] Preferably, the magnetic flux guide element is formed at a temperature of 140 °C or less. Surprisingly, the bonded powder particles can be cured in the mold at a temperature of up to 120 °C, which is significantly lower than conventional high temperatures. In conventional manufacturing of magnetic flux guide elements, such as magnetic cores as powder-pressed cores, the powder material is filled into steel molds, and the soft magnetic particles are pressed together under high pressures greater than 700 MPa and at high temperatures greater than 500 °C.

[0022] It is possible to produce a mold in which

[0023] - a replica of the magnetic flux guide element to be manufactured is produced,

[0024] - the image is arranged in a container, and

[0025] - the mold is produced in the container, wherein the image is positioned inside the mold at the location that specifies the position and orientation of the cavity in the mold.

[0026] It is possible that

[0027] - the image is then removed from the mold, and

[0028] - an access to the cavity is created in the mold through which the powder material or the powder-binder mixture can be filled into the cavity of the mold.

[0029] Instead of an evacuation unit connected to the cavity, the entire mold can also be placed in an evacuation device, such as a vacuum cabinet or vacuum chamber. In this method, for example, the mold, with the powder-binder mixture contained in the cavity, can be completely placed in an evacuation device, and the cavity can be evacuated within the device. 2024PF00389 Foreign version

[0030] One further development process involves installing the mold, containing the hardened and bonded powder particles within the cavity, into the electrical device. In other words, the magnetic flux guide element formed within the mold cavity is installed in the electrical device along with the mold. This allows the mold itself to serve as a simple protective cover (also called a protective layer) for the magnetic flux guide element, which is formed from a soft magnetic powder material.

[0031] However, it is also possible to remove the mold before installing the flow guide element. Removing the mold is particularly feasible if it is a silicone mold. For example, the mold could be a two-part silicone mold, with the two halves being separable to remove the flow guide element.

[0032] Preferably, an adhesive is used as the binder. For example, a two-component epoxy-based adhesive is used as the binder.

[0033] It is possible that the mold is made of multiple parts. In particular, if the mold is made of multiple parts, but also if it is a single piece, it is possible that the mold contains or is made of silicone. A silicone mold has the advantage that the bonding agent adheres only minimally or not at all to the mold, and the magnetic flux guide element can be removed from the mold relatively easily. The magnetic flux guide element can then be installed in an electrical device without a mold.

[0034] The electrical device according to the invention comprises at least one magnetic flux guiding element, which is manufactured according to the method described above. In other words, 2024PF00389 foreign version

[0035] Paragraph 5 of the present invention also relates to an electrical device comprising the flux guiding element described herein. For example, the electrical device may be a transformer or an inductor. The magnetic flux guiding element may be arranged in the electrical device with or without a mold.

[0036] The device according to the invention for manufacturing the at least one magnetic flux guiding element comprises at least:

[0037] - a mold with a fillable cavity for forming the magnetic flux guide element, in particular as a 3D casting element,

[0038] - a first filling unit that can be connected or is connected to the fillable cavity for filling the cavity with a soft magnetic powder material or a powder-binder mixture,

[0039] - an evacuation unit that can be connected to or is connected to the filled cavity for evacuating air from the filled cavity, or an evacuation device in which the mold can be fully arranged for evacuating air from the cavity, and

[0040] - optionally a second filling unit which can be connected or is connected to the filled and evacuated cavity for filling airless areas in the cavity with a binder.

[0041] A second filling unit should be provided, in particular, if the powder material and the binder are filled into the cavity separately. However, if a powder-binder mixture is filled directly into the cavity, a second filling unit is unnecessary and can be omitted.

[0042] For example, the mold can be multi-part. In particular, the mold can be two-part, consisting of an upper casting and a lower casting. The mold, and especially if it is multi-part, 2024PF00389 Foreign version

[0043] The mold, for example, can be made of silicone. A silicone mold has the advantage that the magnetic flux guide element can be removed from the mold relatively easily, since there is usually little or even no adhesion between the flux guide element and the mold. In particular, the binder typically adheres much less strongly to silicone than to other materials, which facilitates easy removal of the flux guide element from the mold. Alternatively, the mold can be a single piece and comprise a closed cavity (also called a hollow chamber) with connecting sections.

[0044] Preferably, the mold can be made of a material that is dimensionally stable up to a temperature of 140°C, in particular a thermoplastic material.

[0045] In particular, the mold can be manufactured using 3D printing, especially from an insulating fluid-resistant material with a temperature resistance of up to 140°C.

[0046] As already mentioned, it is also possible for the mold to be made of silicone. Such a silicone mold, as well as a multi-part mold made of another material, can be produced, for example, by first creating a model of the flow guide element to be manufactured. This model can be produced, for example, using a 3D printing process. Alternatively, the model can be created by assembling several structures. The multiple structures from which the flow guide element is assembled can also be produced using a 3D printing process. Furthermore, a container can be provided for the production of a multi-part mold, and especially a silicone mold, which also includes the production of the container. Such a container can, for example, be produced using a 3D printing process. The container should be 2024PF00389 foreign version.

[0047] 7 in particular dimensioned so that the image of the flow guide element to be manufactured fits completely into the container .

[0048] To produce a multi-part mold, such as a two-part silicone mold, the container can be filled in a multi-stage, particularly two-stage, process. If the mold is produced in two parts, the model can be positioned during the two-stage filling process so that it is located within the mold at the point where the actual flow guide element will later be produced. It is particularly advantageous if the model is located between the two halves of the mold, so that the mold completely encloses the model and subsequently the actual flow guide element. The model can then be removed from the multi-part mold, creating a cavity with the contour of the model in which the flow guide element can be produced. The flow guide element produced in the cavity then has the same external shape as the model.

[0049] Accordingly, the mold is removed from the multi-part casting to produce the flow guide element. Subsequently, at least one access point can be created in the casting through which the cavity can be filled with a powder material or a powder-binder mixture. This access point can, for example, be a bore. The outer end of the bore can be fitted with or connected to a funnel through which the cavity can be filled with the powder material or powder-binder mixture.

[0050] In a method for manufacturing a flow guide element using the multi-part mold just described, in particular using a two-part silicone mold, a powder-binder mixture is preferably filled into the cavity through the access point. The binder is preferably 2024PF00389 foreign version

[0051] 8. A low-viscosity, two-component epoxy adhesive. It is preferred that enough powder-binder mixture is added to completely fill the cavity.

[0052] The mold, with its filled cavity, is then transferred to an evacuation device, such as a vacuum cabinet or vacuum chamber. In the evacuation device, the cavity filled with the powder-binder mixture is evacuated. During this process, air is forced out of the cavity through the access point to the outside of the mold. Consequently, air escapes from the cavity and the powder-binder mixture within it during evacuation.

[0053] At a temperature below 140 °C, e.g., at a temperature between 80 °C and 140 °C, and preferably at a temperature of approximately 120 °C, the binder of the powder-binder mixture is cured. Preferably, the flow guide element to be manufactured remains in the evacuation device during curing.

[0054] After curing, the multi-part mold can be removed from the flow guide element. A silicone mold has the advantage that there is usually low adhesion between the binder and the silicone mold, so the mold can be easily removed. The mold could then be reused to produce another flow guide element.

[0055] Excess material protruding from the flow guide element is subsequently removed. Such excess material may be located, for example, at the point on the flow guide element where material was previously poured into the cavity through the access point.

[0056] The flow guide element can then be used without the mold or any other housing, an electrical 2024PF00389 foreign version.

[0057] 9

[0058] to manufacture a device such as a transformer or a choke.

[0059] 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 readily understandable in connection with the following description of exemplary embodiments, which are explained in more detail in conjunction with the drawings. These drawings show:

[0060] FIG 1 schematically and by way of example a device for manufacturing a magnetic flux guide element for an electrical device,

[0061] FIG 2 schematically and by way of example an electrical device with a magnetic flux guide element,

[0062] Figures 3 to 9 schematically and exemplarily show intermediate products of a process for manufacturing a magnetic flux guide element for an electrical device, and

[0063] Fig. 4 schematically and by way of example another electrical device with a magnetic flux guide element .

[0064] Corresponding parts are marked with the same reference symbols in the figures.

[0065] Figure 1 schematically shows a device 1 for manufacturing a magnetic flux guide element 2 for an electrical device 4 (shown in Figure 2).

[0066] The magnetic flux guiding element 2 to be manufactured is, for example, a magnetic element, in particular a magnetic core, which can be installed in the electrical device 4.

[0067] Electrical device 4 is, in particular, a high-voltage element for a high-voltage network. For example, electrical device 4 is a transformer, in particular a 2024PF00389 foreign version.

[0068] 10

[0069] Power transformer, or a choke, in particular a power choke.

[0070] The device 1 comprises at least one mold 1.1 with a fillable cavity 1.2 for forming the magnetic flux guide element 2, in particular as a 3D casting element. The mold 1.1 is also referred to as a hollow mold.

[0071] The device 1 further comprises a first filling unit 1.3, which is connectable to or connected with the fillable cavity 1.2 for filling the cavity 1.2 with a soft magnetic powder material 2.1 or with a powder-binder mixture. The first filling unit 1.3 can, for example, comprise a first filling element 1.3.1, in particular a filling nozzle or a filling valve, which is coupled on the one hand to a powder storage container 1.3.2 in which the soft magnetic powder material 2.1 is stored, and on the other hand directly to the mold 1.1, in particular the cavity 1.2, for filling the cavity 1.2 with the soft magnetic powder material 2.1 from the powder storage container 1.3.2.

[0072] Furthermore, the device 1 comprises an evacuation unit 1.4, which is connectable to or connected with the filled cavity 1.2 for evacuating air from the filled cavity 1.2. The evacuation unit 1.4 comprises, for example, an evacuation valve 1.4.1, which is coupled on one side directly to the cavity 1.2 and on the other side to a vacuum pump 1.4.2 for evacuating the air from the filled cavity 1.2. Alternatively or additionally to the evacuation unit, the device may also include an evacuation device such as a vacuum chamber or a vacuum cabinet in which the casting element may be fully arranged to evacuate the cavity. 2024PF00389 Foreign version

[0073] 11

[0074] Furthermore, the device 1 comprises an optional second filling unit 1.5, which can be connected to, or is connected to, the filled and evacuated cavity 1.2 for filling airless areas in the cavity 1.2 with a binder 6. The second filling unit 1.5 can, for example, comprise a second filling element 1.5.1, in particular a filling nozzle or a filling valve, which is coupled on one side to a container 1.5.2 in which the binder 6 is stored, and on the other side directly to the mold 1.1, in particular the cavity 1.2, for filling the cavity 1.2 with the binder 6 from the container 1.5.2. If a powder-binder mixture is to be filled into the cavity, the evacuation unit 1.4 can be omitted.

[0075] For example, the mold 1.1 can be multi-part. In particular, the mold 1.1 can be formed in two parts, consisting of a casting upper part and a casting lower part, for example as described with reference to Figures 3 to 9. Alternatively, the mold 1.1 can be a single piece and comprise a closed cavity 1.2 (also called a hollow chamber) with connection interfaces 1.2.1 for the filling units 1.3 and 1.5 and the evacuation unit 1.4.

[0076] Preferably, the mold 1.1 can be made of a material that is dimensionally stable up to a temperature of 140°C, in particular a thermoplastic material. It is also possible that the mold 1 is made of silicone or contains silicone.

[0077] Preferably, the mold 1.1 can be manufactured by means of 3D printing, in particular from an insulating fluid-resistant material with a temperature resistance of up to 140°C. 2024PF00389 Foreign version

[0078] 12

[0079] An exemplary method for manufacturing a magnetic flux guiding element 2, in particular by means of the device 1, can comprise at least the following steps:

[0080] - Providing the mold 1.1 with the fillable cavity 1.2,

[0081] - Filling the cavity 1.2 with the soft magnetic powder material 2.1,

[0082] - Airtight sealing of the mold 1.1 with the filled cavity 1.2,

[0083] - Evacuating the filled cavity 1.2,

[0084] - Filling of airless areas formed as a result of evacuation in cavity 1.2 with the binder 6 and

[0085] - Shaping the magnetic flux guiding element 2 in cavity 1.2.

[0086] The shape of the cavity 1.2 of the mold 1.1 corresponds in particular to the shape of the flux guide element 2 to be manufactured. In other words, the magnetic flux guide element 2 is cast using the mold 1.1 and formed as a casting with a 3D structure. Complex geometries can be easily manufactured using such a 3D-cast magnetic flux guide element 2. Furthermore, such a magnetic flux guide element 2 made of a soft magnetic powder material 2.1 reduces or even eliminates electrical losses, especially eddy current losses, and temperature increases.

[0087] The cavity 1.2 is filled with the soft magnetic powder material 2.1 using the first filling unit 1.3.

[0088] The evacuation of the filled cavity 1.2 is carried out using the evacuation unit 1.4.

[0089] Evacuating cavity 1.2 leads to the formation of vacuum zones within cavity 1.2, particularly between the powder particles of powder material 2.1. 2024PF00389 Foreign version

[0090] 13

[0091] These airless spaces between the powder particles are filled with the binder 6 by means of the second filling unit 1.5. The powder particles can then be bonded together by means of the binder 6.

[0092] Surprisingly, the powder particles bonded together in the mold 1.1 can be cured at a temperature, especially a low one, of up to 120°C.

[0093] Preferably, the mold 1.1, with the powder particle material 2.1 hardened in the cavity 1.2 and formed into the magnetic flux guide element 2, is installed as a whole in an electrical device 4 as described with reference to Figure 2. In other words, the magnetic flux guide element 2 formed in the cavity 1.2 of the mold 1.1 can be installed in the electrical device 4 together with the mold 1.1. In this way, the mold 1.1 itself simply forms a protective cover 8 (also called a protective layer, as shown in Figure 2) for the magnetic flux guide element 2 formed from the soft magnetic powder material 2.1.

[0094] Preferably, an adhesive is used as the binder 6. For example, a two-component epoxy-based adhesive is used as the binder 6.

[0095] Another method for manufacturing the magnetic flux guide element is described below with reference to Figures 3 to 9.

[0096] Figure 2 schematically shows an exemplary electrical device 4 with a magnetic flux guide element 2 as described with reference to Figure 1, which is installed in the electrical device 4 with the mold 1.1 serving as a protective cover 8. An alternative electrical device in which the magnetic flux guide element is installed without a mold is described below with reference to Figure 10. 2024PF00389 Foreign version

[0097] 14

[0098] For example, the mold 1.1 has a rectangular ring shape in which the magnetic flux guiding element 2 is formed as a rectangular ring mold.

[0099] The mold 1.1 together with the flux guide element 2 formed therein form a core 4.1 of the electrical device 4, for example a transformer, in which a magnetic flux 100 flows.

[0100] For example, a coil unit 10 is wound on one of the legs 4.2 of the electrical device 4.

[0101] Based on Figures 3 to 9, an alternative method for manufacturing a magnetic flux guide element is described below.

[0102] Figure 3 shows an exemplary and schematic representation of a magnetic flux guide element 300. In Figure 3, the representation 300 is shown with a rectangular base. However, the representation 300 could also have other shapes, depending on the application of the magnetic flux guide element. For example, the representation 300 could also have a rectangular shape, e.g., square, or a circular ring shape. The representation 300 can be manufactured, for example, using a 3D printing process. The representation 300 can also be composed of several structures, for example, bonded together. The individual structures can also be manufactured using a 3D printing process.

[0103] Figure 4 shows a schematic and exemplary view of the image 300 arranged in a container 400. The container 400 is dimensioned so that the image 300 fits completely inside it. The container 400 can also be manufactured, for example, using a 3D printing process. 2024PF00389 Foreign version

[0104] 15

[0105] Figure 5 schematically and exemplarily shows in a sectional view that a two-part silicone mold 500 is arranged in the container 400, enclosing the model 300. The two halves 502, 504 of the mold 500 can be produced by a two-stage filling of the container 400. The solidified silicone of the two halves 502, 504 then forms the mold 500.

[0106] As shown schematically and by way of example in Figure 6, the image 300 is then removed from the mold 500, so that by joining the two halves 502, 504 at the place where the image 300 was previously, a cavity 600 is created.

[0107] Figure 7 schematically and by way of example shows that an access point 700 to the cavity 600 is arranged in the mold 500. The access point 700 can, for example, be a bore. The access point 700 is specifically arranged in one of the halves 502 of the mold 500. This half 502 can, for example, be the upper half of the mold 500. A funnel 702 is arranged at the access point 700 and outside the mold 500, through which the cavity 600 can be filled with a soft magnetic powder-binder mixture. The access point 700 thus connects the cavity 600 to the funnel 702 and makes it possible to fill the cavity 600 with a powder-binder mixture through the funnel 702.

[0108] Figure 8 schematically and by way of example shows that a powder-binder mixture 800 is arranged in the cavity 600, through the access point 700, and into the funnel 702. The mold 500 with the filled powder-binder mixture 800 can then be transferred to an evacuation device, for example, a vacuum chamber or a vacuum cabinet. Evacuation allows air to escape from the cavity 600 and through the access point 700 and the funnel 702 to the outside of the mold. 2024PF00389 Foreign version

[0109] 16

[0110] The powder-binder mixture 800 can then be cured, particularly at a temperature of 140 °C or less, preferably at approximately 120 °C. The resulting flow guide element 900 can then be removed from the mold 500 and the excess material removed from the access point 700 and the hopper 702. The flow guide element 900 produced in this way is shown schematically and by way of example in Figure 9.

[0111] Figure 10 schematically and by way of example shows another electrical device 1000 with a magnetic flux guide element 1002, which was manufactured according to the method described in Figures 3 to 9. The magnetic flux guide element 1002 is formed as a rectangular ring casting.

[0112] In contrast to the electrical device 4 described with reference to Figure 2, the magnetic flux guide element 1002 of the electrical device 1000 is installed without a mold or other protective cover.

[0113] The flux guide element 1002 serves as the core 1004 of the electrical device 1000. During operation of the electrical device 1000, a magnetic flux 1006 flows in the core 1004. A coil unit 1010 is arranged on one of the legs 1008 of the electrical device 1000.

[0114] The electrical device 1000 could, for example, be a transformer or a choke.

[0115] Although the invention has been further illustrated and described in detail by means of preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by the person skilled in the art without leaving the scope of protection of the invention.

Claims

2024PF00389 Foreign version 17 Patent claims 1. Method for manufacturing at least one magnetic flux guide element for an electrical device, comprising the following steps: - Providing a mold with a fillable cavity, - Filling the cavity with a soft magnetic powder material or a powder-binder mixture, - Evacuating the filled cavity, and - Shaping the magnetic flux guide element in the cavity.

2. The method of claim 1, wherein the magnetic flux guiding element is formed at a temperature of 140 °C or less.

3. The method of claim 1 or 2, comprising the further steps of: - Airtight sealing of the mold (1.1) , and - Filling the vacuum areas formed in the cavity as a result of evacuation with a binding agent.

4. Method according to at least one of the preceding claims, wherein, after evacuation, the airless areas formed between powder particles of the soft magnetic powder material are filled with the binder.

5. Method according to claim 1 or 2, wherein - a replica of the magnetic flux guide element to be manufactured is produced, - the image is arranged in a container, and - the mold is produced in the container, wherein the image is arranged inside the mold at the location that specifies the position and orientation of the cavity in the mold. 2024PF00389 Foreign version 18 6. Method according to claim 5, wherein - the image is then removed from the mold, and - an access to the cavity is created in the mold through which the powder material or the powder-binder mixture can be filled into the cavity of the mold.

7. Method according to at least one of claims 1, 2, 5 or 6, in which the mold with powder-binder mixture arranged in the cavity is completely arranged in an evacuation device and the cavity is evacuated in the evacuation device.

8. Method according to at least one of the preceding claims, wherein the powder particles of the soft magnetic powder material are bonded together by means of the binder.

9. The method according to claim 8, wherein the powder particles bonded together are cured in the mold at a temperature of up to 120°C.

10. Method according to at least one of the preceding claims, wherein an adhesive is used as the binder.

11. Method according to at least one of the preceding claims, wherein a two-component epoxy-based adhesive is used as the binder.

12. Method according to at least one of the preceding claims, wherein the mold is designed in multiple parts.

13. Method according to at least one of the preceding claims, wherein the mold comprises silicone. 2024PF00389 Foreign version 19 14. Electrical device comprising at least one magnetic flux guiding element manufactured according to a method according to at least one of the preceding claims.

15. Electrical device according to claim 14, which is a transformer or a choke.

16. Device for manufacturing at least one magnetic flux guide element for an electrical device, comprising at least: - a mold with a fillable cavity for forming the magnetic flux guide element, - a first filling unit that is connectable or connected to the fillable cavity for filling the cavity with a soft magnetic powder material or a powder-binder mixture, and - an evacuation unit that can be connected to or is connected to the filled cavity for evacuating air from the filled cavity, or an evacuation device in which the mold can be fully arranged for evacuating air from the cavity.

17. Device according to claim 16, further comprising: - a second filling unit which can be connected or is connected to the filled and evacuated cavity for filling airless areas in the cavity with a binder 18. Device according to claim 16 or 17, wherein the mold is formed in multiple parts.

19. Device according to claim 16 or 17, wherein the mold is formed in one piece and comprises a closed cavity with connection interfaces. 2024PF00389 Foreign version 20 20. Device according to at least one of claims 16 to 19, wherein the mold is made of a material that is dimensionally stable up to a temperature of 140°C.

21. Device according to at least one of claims 16 to 20, wherein the mold is manufactured using 3D printing, in particular from an insulating fluid-resistant material with a temperature resistance of up to 140°C.

22. Device according to claim 18, wherein the mold comprises or consists of silicone.

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