Magnetic core and energy transfer system with magnetic core

Abstract

The present invention relates to a magnetic core (1), in particular a powder core or ferrite core, for conducting or shielding or generating a magnetic flux, wherein the magnetic core (1a) is made of powdered or granular core material (3), in particular based on iron or iron oxide or soft magnetic compound, and forms a body, characterized in that the magnetic core (1) has a dimensionally stable carrier shell (2) for forming the body, into which the core material (3) is filled and / or pressed in loose powder or granular form.

Description

State of the art

[0001] The present invention relates to a magnetic core. The magnetic core is particularly suitable for use in an energy transmission system, especially preferably in a rotary transformer.

[0002] Magnetic cores in the form of sintered powder material are known from the prior art. This powder material is, for example, ferrite powder. To increase the stability of the magnetic cores during assembly, plastoferrite, which consists of ferrite powder in a polymer matrix, is also used. Such magnetic cores can be used, for example, to conduct a magnetic flux. Disclosure of the invention

[0003] The magnetic core according to the invention enables maximized fill levels of the magnetic core with a core material. This is achieved by using a stable carrier shell into which the core material is introduced in powder or granular form. In addition to a high fill level, tolerances of the magnetic core are also improved, for example, compared to sintered magnetic cores. Furthermore, the use of inexpensive semi-finished products such as ferrite powder is possible, thereby achieving cost reductions.

[0004] The magnetic core according to the invention is in particular a powder core or ferrite core and is designed to conduct, shield, or generate a magnetic flux. The resulting manipulation of the magnetic flux allows, in particular, the suppression of interference in an electrical machine. The magnetic core is made of powdered or granular core material. The core material is based, in particular, on iron or iron oxide or soft magnetic composites, also known as soft magnetic compounds. The magnetic core forms a body, in particular a stable one, which can be used, especially preferably, as a component of an electrical machine.

[0005] The magnetic core is formed by a dimensionally stable support shell. The core material, in loose powder or granule form, is filled and / or pressed into this support shell. This allows the entire volume enclosed by the support shell to be filled with the core material, resulting in high fill levels of the magnetic core. In particular, the support shell is designed with thin walls.

[0006] The carrier shell is primarily a component that shapes the magnetic core. It serves as a receptacle for the core material, which can therefore remain in loose powder or granular form. The core material itself does not need to be dimensionally stable. The core material, filled and / or pressed into the carrier shell, can thus be dimensionally unstable on its own, i.e., without the carrier shell.

[0007] The combination of the carrier shell and core material allows for optimal mounting of the magnetic core, especially as part of an electric machine. Handling of the magnetic core is simplified, and the risk of damage during installation in the electric machine is minimized. Furthermore, the high filler density of the magnetic core gives it optimal magnetic properties.

[0008] The dependent claims describe preferred embodiments of the invention.

[0009] The magnetic core is specifically a soft magnetic ferrite core. This optimizes the magnetic properties. Furthermore, this design makes the magnetic core cost-effective to manufacture.

[0010] The core material preferably consists of pre-sintered material. This simplifies the production of the magnetic core, as the pre-sintered material can simply be inserted into the carrier shell.

[0011] The core material comprises, in particular, at least one further metal selected from the soft magnetic group manganese, nickel, cobalt, copper, magnesium, cadmium, and zinc, or from the hard magnetic group barium, strontium, and cobalt. Preferably, the core material has a composition according to the molecular formula Mn w Zn x Fe y O z or Ni w Zn x Fe y O z for soft magnetic ferrites or SrFe a O b or BaFe a O b or CoFe y O z for hard magnetic ferrites. It is particularly advantageous if the parameter a is between 2 and 14 and / or b is between 17 and 21 and / or the parameter w is between 0.1 and 1.0 and / or the parameter x is between 0.1 and 1.0 and / or the parameter y is between 1.0 and 3.0 and / or the parameter z is between 3.0 and 5.0. Such a material is, in particular, a soft magnetic and / or hard magnetic ferrite.

[0012] The carrier shell preferably comprises a receiving part with an open filling volume for filling with the core material and at least one lid part for closing the receiving part. The receiving part and / or the lid part are dimensionally stable. Closing the receiving part with the lid part prevents core material from escaping the carrier shell. Before closing the receiving part with the lid part, it can be easily and efficiently filled with the core material.

[0013] Preferably, the receiving part and the lid part are joined by a material bond. This material bond is achieved particularly by welding or bonding. In an additional or alternative embodiment, the receiving part and the lid part are joined by a force-fit connection. This force-fit connection is preferably achieved by pressing the lid part into the receiving part. Alternatively or more preferably, a positive-locking connection between the lid part and the receiving part is provided. This positive-locking connection is preferably achieved by forming, by a snap-fit ​​connection, or by a snap closure. These joining methods allow for a secure fit of the lid part in the receiving part, ensuring that the carrier shell is reliably sealed. This results in a stable magnetic core and ensures that the core material is reliably held within the carrier shell.

[0014] In an advantageous embodiment, the lid part at least partially surrounds the receiving part. For example, the lid part and receiving part can be U-shaped, with the U-shape of the lid part encompassing the U-shape of the receiving part to form a closed body. This allows, on the one hand, rapid filling of the receiving part with the core material, and on the other hand, quick and tight assembly of the carrier shell from the receiving part and the lid part.

[0015] A further plastic shell is preferably injection-molded onto the dimensionally stable carrier shell. This plastic shell allows for the formation or integration of additional functional components for mounting the magnetic core in an electric machine. The carrier shell shields the core material before the injection molding process. Furthermore, the injection molding of a plastic shell reliably holds the core material within the receiving part. The plastic shell also preferably provides a reliable seal, preventing the escape of core material 3. Preferably, the plastic shell at least partially encloses the carrier shell.

[0016] The dimensionally stable carrier shell preferably has at least one spacer. The spacer is designed to position the carrier shell in an injection mold. This enables reliable injection molding of another plastic shell. Due to the spacer, inserting the carrier shell into the injection mold automatically establishes a target position within the mold. This increases process reliability and reduces the effort required to manufacture the additional plastic shell.

[0017] The dimensionally stable support shell advantageously has a wall thickness of less than 1.0 millimeter and preferably at least 0.1 millimeter. This thin-walled design allows for a high fill level of the core material within the entire magnetic core. The wall thickness is primarily intended to ensure the dimensional stability of the support shell, while being minimized for other purposes.

[0018] Preferably, the dimensionally stable support shell is manufactured by deep drawing or injection molding. This allows for a thin-walled design and minimizes manufacturing costs. If the support shell has a receiving part and a cover part as described above, each component—i.e., the receiving part and the cover part—can be manufactured independently of the other component by deep drawing or injection molding. These manufacturing processes also reduce tolerances, for example, compared to sintered components.

[0019] Furthermore, it is preferably provided that the dimensionally stable support shell is made of a plastic. The plastic is in particular a thermoplastic polymer or a thermosetting polymer. The use of plastic for manufacturing the support shell increases the impact strength of the magnetic core, especially compared to sintered components.

[0020] The invention also relates to an energy transfer system. This energy transfer system is, in particular, a rotary transformer. The energy transfer system serves for the contactless transfer of electrical energy to an excitation winding of a rotor of an electric machine. The energy transfer system comprises a static primary unit and a secondary unit rotatable about a transformer axis. The primary unit and / or the secondary unit has a magnetic core as described above. The magnetic core serves, in particular, to guide or shield a magnetic flux between the primary unit and the secondary unit. This enables both reliable energy transfer and interference suppression of the electric machine. The magnetic core can be easily and reliably mounted in the electric machine, especially due to its support casing, thereby minimizing the risk of damage to the magnetic core.Furthermore, the possibility of high fill levels of the magnetic core with core material ensures reliable functionality of the magnetic core. Brief description of the drawings

[0021] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. The drawing shows: Fig. 1 a schematic view of an electric machine with an energy transfer system according to an embodiment of the invention, Fig. 2a-c schematic sectional views of a magnetic core according to a first embodiment of the invention during various phases of manufacture, Fig. 3 a schematic spatial sectional view of the magnetic core according to the first embodiment of the invention, Fig. 4a-c Schematic sectional views of a magnetic core according to a second embodiment of the invention during various phases of manufacture, Fig. 5 a schematic spatial sectional view of the magnetic core according to the second embodiment of the invention, Fig. 6a-d schematic sectional views of a magnetic core according to a third embodiment of the invention during different phases of manufacture, Fig. 7 a schematic spatial sectional view of the magnetic core according to the third embodiment of the invention, and Fig. 8 a schematic spatial sectional view of a magnetic core according to a fourth embodiment of the invention. Embodiments of the invention

[0022] Preferably, all identical components, elements and / or units in all figures are provided with the same reference numerals.

[0023] Fig. Figure 1 schematically shows an electric machine 10 with a stator 8 and a rotor 9. The rotor 9 has an excitation winding 9a, which is to be supplied with electrical energy. For this purpose, the electric machine 10 has an energy transfer system 13, which is in particular a rotary transformer. The energy transfer system 13 is designed for the contactless transfer of electrical energy to the excitation winding 9a of the rotor 9. The contactless energy transfer allows for the avoidance of slip rings or similar components, making the energy transfer system 13 wear-free or virtually wear-free. The energy transfer system 13 has a static primary unit 11 and a secondary unit 12 rotatable about a transformer axis 100, the secondary unit 12 being electrically coupled to the excitation winding 9a of the rotor 9.In the illustrated embodiment, the primary unit 11 has a primary winding 11a and the secondary unit 12 has a secondary winding 12a. In this embodiment, the primary unit 11 also has a magnetic core 1 according to an embodiment of the invention. Alternatively or additionally, the secondary unit 12 can also have such a magnetic core 1.

[0024] The magnetic core 1 serves to conduct and / or shield the electrical flux between the primary winding 11a and the secondary winding 12a. In this way, the electrical machine 10 can be shielded from interference, so that any influence or disturbance from the energy transfer system 13 is minimized.

[0025] The following will refer to the Fig. Sections 2 to 8 describe different embodiments of the magnetic core 1, which can be used in the electric machine 10, in particular the energy transfer system 13. In all cases, a support shell 2 is provided to hold a core material 3. The magnetic core 1 is designed as a powder core or a ferrite core.

[0026] The Fig. Figures 2a to 2c show different states during the manufacture of a magnetic core 1 according to a first embodiment of the invention. Fig. Figure 3 shows a schematic view of the magnetic core 1 according to the first embodiment of the invention.

[0027] The magnetic core 1 has a dimensionally stable support shell 2, which defines the shape of the magnetic core 1. The support shell 2 includes a receiving part 4 with an open filling volume for filling with the core material 3. This is in Fig. 2a shown. A core material 3 in loose powder or loose granule form is filled and / or pressed into this receiving part 4, which in Fig. Figure 2b shows that a high degree of filling is achieved in this way. The receiving part 4 is sealed with a cover part 5 of the carrier shell 2, thus preventing the core material 3 from escaping the carrier shell 2.

[0028] The combination of the carrier shell 2 and the core material 3 offers the advantage that, on the one hand, the carrier shell 2 provides stability to the magnetic core 1, thus simplifying its handling during assembly in the electric machine 10. The use of the powdered or granular core material 3 allows for a high fill level in the magnetic core 1 and therefore optimal magnetic properties.

[0029] The receiving part 4 and the cover part 5 are connected to each other. This connection can be designed in different ways. In a first variant, a material-bonded connection is provided, preferably by welding or bonding. In a second variant, the connection is force-fit, preferably by pressing the cover part 5 into the receiving part 4. In a further variant, the connection is form-fit, for example by forming, by a snap-fit ​​connection, or by a snap closure. The individual variants can also be combined with each other. Thus, a secure closure of the receiving part 4 by the cover part 5 is achieved.

[0030] The core material 3 is, in particular, a powdered or granular material 3 based on iron or iron oxide or a soft magnetic compound. Preferably, a soft magnetic and / or hard magnetic ferrite core is formed in this way, wherein the core material 3 may, for example, be fully sintered material. The core material 3 also preferably comprises at least one further metal. The metal is selected from the soft magnetic group manganese, nickel, cobalt, copper, magnesium, cadmium, and zinc, or from the hard magnetic group barium, strontium, and cobalt, wherein, in particular, a composition according to the molecular formula Mn w Zn x Fe y O z or Ni w Zn x Fe y O z for soft magnetic ferrites or SrFe a O b or BaFe a O b or CoFe y O zThis is given for hard magnetic ferrites. In an example composition, the parameter a, which indicates the proportion of iron in a hard magnetic ferrite, lies between 10 and 14, the parameter b, which indicates the proportion of oxygen in a hard magnetic ferrite, lies between 17 and 21, the parameter w, which indicates the proportion of manganese and / or nickel, lies between 0.1 and 1.0, the parameter x, which indicates the proportion of zinc, lies between 0.1 and 1.0, the parameter y, which indicates the proportion of iron, lies between 1.0 and 3.0, and the parameter z, which indicates the proportion of oxygen, lies between 4.0 and 5.0.

[0031] The combination of the carrier shell 2 and the core material 3 results in a dimensionally stable magnetic core 1. In contrast to the sintering of the magnetic core as described above, the magnetic core 1 according to the first embodiment can be handled easily and safely when inserted into the electric machine 10. The risk of damage or destruction of the magnetic core 1 is reduced. Furthermore, optimal magnetic properties are achieved.

[0032] To achieve a high fill level of the magnetic core 1, the dimensionally stable support shell 2 is designed with thin walls. Thin walls refer specifically to a wall thickness d of less than 1.0 millimeter and preferably at least 0.1 millimeters. This minimizes the volume fraction of the support shell 2 and maximizes the volume fraction of the core material 3. Since the core material 3 is particularly relevant for the function of the magnetic core 1, optimal magnetic behavior of the magnetic core 1 is thus achieved.

[0033] The dimensionally stable support shell 2 is primarily made of plastic. It is manufactured, for example, by deep drawing or injection molding. The plastic is primarily a thermoplastic polymer or a thermosetting polymer. This allows for the simple and cost-effective production of various geometries for the support shell 2. Furthermore, the support shell 2 can be designed with stability.

[0034] In the first embodiment, the magnetic core 1 is essentially ring-shaped, with an L-shaped cross-section. The cover part 5 is provided at the largest end face, thus enabling simple and reliable filling with the core material 3.

[0035] The Fig. Figures 4a to 4c show different states during the manufacture of a magnetic core 1 according to a second embodiment of the invention. Fig. Figure 5 shows a schematic view of the magnetic core 1 according to the second embodiment of the invention. The essential difference from the first embodiment is the shape. The magnetic core 1 is again ring-shaped, with a cuboid cross-section. The Fig. The receiving part 4 of the carrier shell 2 shown in 4a has a C-shaped cross-section, so that the core material 3 can be received easily and reliably, which is Fig. 4b is shown. The cover part 5 closes the receiving part 4 and thus forms the cuboid shape of the magnetic core 1 or the carrier shell 2 from the C-shape of the receiving part 4, which is shown in Fig. 4c is shown.

[0036] The design of the carrier shell 2 and core material, in particular the fastening of the cover part 5 and the receiving part 4, is analogous to the first embodiment. As in particular in Fig. As shown in Figure 1, the magnetic cores 1 can be used together in the electric machine 10 according to the first embodiment and the second embodiment.

[0037] The Fig. Figures 6a to 6d show different states during the manufacture of a magnetic core 1 according to a third embodiment of the invention. Fig. Figure 7 shows a schematic view of the magnetic core 1 according to the first embodiment of the invention.

[0038] Analogous to the previously mentioned embodiments, the magnetic core 1 is again formed by a core material 3 as in the above embodiments, which is surrounded by a support shell 2. The support shell 2 has a receiving part 4, which is essentially analogous to the receiving part 4 as in the second embodiment, but additionally has a spacer 6. The function of the spacer will be explained later with reference to Fig. 6d and Fig. Section 7 explains. Recording section 4 is in Fig. 6a shown.

[0039] As in the above embodiments, the receiving part 4 is filled with the core material 3, which in Fig. 6b is shown, and closed with a lid part 5, which is in Fig. Figure 6c shows that the cover part 5 at least partially surrounds the receiving part 4. This results in the receiving part 4 being closed, although fastening the receiving part 4 and the cover part 5 to each other is optional and not mandatory. The cover part 5 also has a spacer 6.

[0040] The spacers 6 of the carrier shell 2 allow the carrier shell 2 to be positioned in an injection mold. This enables the injection molding of another plastic shell 7 onto the dimensionally stable carrier shell 2. The spacers 6 facilitate the simple and reliable positioning of the carrier shell 2 in the injection mold, allowing a uniform plastic shell 7 to be formed around the carrier shell 2. The plastic shell 7 at least partially encloses the carrier shell 2. In particular, the plastic shell 7 ensures that the carrier shell 2 is sealed, i.e., that no core material 3 can escape from the composite of carrier shell 2 and plastic shell 7.

[0041] As especially a Fig. As shown in Figure 7, the magnetic core 1 is ring-shaped, with one cross-section being cuboid. Overmolding with the plastic shell 7 allows, in particular, the integration of further components into a single-piece body, which simplifies the handling of the magnetic core 1, especially during assembly in the electric machine 10.

[0042] Fig. Figure 8 schematically shows a cross-sectional view through a magnetic core 1 according to a fourth embodiment of the invention. In the fourth embodiment, the magnetic core 1 is essentially identical to that in the first embodiment. The only difference lies in the structure of the support shell 2, the shape of which is the same as in the first embodiment.

[0043] The carrier shell 2 in turn has a receiving part 4, which has two openings, each of which can be closed by a cover part 5. In this way, the core material 3 can be filled at different points, which simplifies the filling process overall and allows for easy maximization of the fill level. The cover parts 5 close the receiving part 4 to prevent leakage of the core material 3. The cover parts 5 are preferably attached to the receiving part 4 as described above.

Claims

[1] Magnetic core (1), in particular powder core or ferrite core, for conducting or shielding or generating a magnetic flux, wherein the magnetic core (1a) is made of powdered or granular core material (3), in particular based on iron or iron oxide or soft magnetic compound, and forms a body, characterized by that the magnetic core (1) has a dimensionally stable carrier shell (2) for forming the body, into which the core material (3) is filled and / or pressed in loose powder or granulate form. [2] Magnetic core (1) according to claim 1, characterized by that the magnetic core (1) is a soft magnetic and / or hard magnetic ferrite core. [3] Magnetic core (1) according to claim 1 or 2, characterized by that the core material (3) comprises finished sintered material. [4] Magnetic core (1) according to one of the preceding claims, characterized bythat the core material (3) comprises at least one further metal selected from the soft magnetic group manganese, nickel, cobalt, copper, magnesium, cadmium and zinc or the hard magnetic group barium, strontium and cobalt, in particular a composition according to the empirical formula Mn w Zn x Fe y O z or Ni w Zn x Fe y O z for soft magnetic ferrites or SrFe a O b or BaFe a O b or CoFe y O z for hard magnetic ferrites. [5] Magnetic core (1) according to one of the preceding claims, characterized by that the carrier shell (2) has a receiving part (4) with an open filling volume for filling with the core material (3) and at least one cover part (5) for closing the receiving part (4). [6] Magnetic core (1) according to claim 5, characterized bythat the receiving part (4) and the cover part (5) are connected in a materially bonded manner, preferably by welding or gluing, and / or in a force-fitting manner, preferably by pressing in, and / or in a form-fitting manner, preferably by forming or by a locking connection or by a snap closure. [7] Magnetic core (1) according to claim 5 or 6, characterized by that the cover part (5) at least partially encompasses the receiving part (4). [8] Magnetic core (1) according to one of the preceding claims, characterized by that a further plastic cover (7) is injection-molded onto the dimensionally stable carrier cover (2). [9] Magnetic core (1) according to one of the preceding claims, characterized by that the dimensionally stable carrier shell (2) has at least one spacer (6) which is designed to position the carrier shell (2) in an injection mold. [10] Magnetic core (1) according to one of the preceding claims, characterized bythat the dimensionally stable carrier shell (2) has a wall thickness (d) of less than 1.0 millimeters and preferably of at least 0.1 millimeters. [11] Magnetic core (1) according to one of the preceding claims, characterized by that the dimensionally stable carrier shell (2) is produced by deep drawing or injection molding. [12] Magnetic core (1) according to one of the preceding claims, characterized by that the dimensionally stable carrier shell (2) is made of a plastic, in particular of a thermoplastic polymer or a thermosetting polymer. [13] Energy transmission system (13), in particular a rotary transformer, for the contactless transmission of electrical energy into an excitation winding of a rotor (9) of an electrical machine (10), comprising a static primary unit (11) and a secondary unit (12) rotatable about a transformer axis (100), wherein the primary unit (11) and / or the secondary unit (12) has a magnetic core (1) according to one of the preceding claims.

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