Ferrite core for electromagnetic device (variants)

Abstract

Disclosed are the embodiments of a ferrite core for an electromagnetic device such as a transformer, an inductor, a throttle, etc. According to one embodiment, the proposed ferrite core consists of two parts, each part having at least two connecting surfaces for connection with the mating part of the core, at least one centering protrusion is provided on one connecting surface, and a recess having a shape matching the shape of the protrusion is provided on the other, corresponding, connecting surface. The core may comprise side protrusions on the connecting surfaces, the protrusions extending in outward directions relative to the central plane of the core. According to another embodiment, the connecting surfaces of the core parts are beveled, and at least two of the connecting surfaces are also convergent in opposite directions. According to yet another embodiment, one or more centering protrusions and recesses are formed on at least one pair of connecting surfaces, and the connecting surfaces of the other pair of connecting surfaces are beveled. The disclosed improvements in the design of ferrite cores allow to increase accuracy of core part assembly by centering the parts during the core assembly process, and to improve magnetic properties of the cores.

Description

FERRITE CORE FOR ELECTROMAGNETIC DEVICE (VARIANTS)Field of the Invention

[0001] The present invention relates to electrical engineering, and more particularly to ferrite cores for electromagnetic devices such as transformers, inductors, chokes, etc.Background of the Invention

[0002] US 4424505 (published on January 3, 1984, IPC H01F 27 / 24) discloses a ferrite core for an electromagnetic device consisting of two parts, each having several connecting surfaces for connection with the mating part of the core. Such a composite design does not allow for accurate centering of the core during assembly. As a result, parts of the core can be connected with an offset, resulting in an unwanted magnetic field.

[0003] The technical problem that the present invention aims to solve is the displacement of the core parts relative to each other during the core assembly process. The solution of this technical problem will contribute to reducing the undesirable magnetic field arising during core operation, reducing the interference caused by such magnetic field, as well as reducing pickup in small-signal transformers during core operation.Summary of the Invention

[0004] The technical problem is solved by a proposed ferrite core for an electromagnetic device, the core consisting of two parts, each part having at least two connecting surfaces for connection with the mating part of the core. One or more centering protrusions are provided on at least one connecting surface, and a recess is provided in the other, corresponding, connecting surface, the shape of the recess matching the shape of the protrusion.

[0005] The technical effect to be achieved by the present invention is the increase in assembling accuracy of the parts of the core by centering said parts during the core assembly process, and the increase in the mating connecting surfaces area of the core parts without forming undesirable gaps between the connecting surfaces, thus allowing for balancing of the core magnetic resistance relative to the central plane of the core and for reducing the magnitude of magnetic resistance between the core parts. The balancing of magnetic resistance is understood as providing approximately equal magnetic resistance on the mating parts (core elements) of the core. Balancing is preferred as it facilitates equal distribution of magnetic fluxes in the core.

[0006] According to one particular embodiment, the core parts have a center core element and side core elements each having a connecting surface, wherein at least one centering protrusion is provided on one connecting surface of each side core element, and a recess matching the protrusion is provided on the other, corresponding, connecting surface of the side core element. This connecting surface design ensures centering of the core parts and provides the increase in the mating surface area of the side core elements, which results in reduction and balancing of magnetic resistance of the core relative to the central plane of the core extending through the center core element.

[0007] According to another particular embodiment, the at least one centering protrusion and the recess corresponding thereto are provided on all connecting surfaces and shaped as a hemisphere, a cone, a truncated cone, a cylinder, a prism, a pyramid, a truncated pyramid or any other stereometric figure. Providing the centering protrusion and corresponding recess on all connecting surfaces further increases centering accuracy and simplifies core assembly process, and the selection of a specific shape further allows prevention of the core from displacement, thus limiting the degrees of freedom, which avoids or, optionally, allows displacement of the core parts in certain directions.

[0008] According to yet another particular embodiment, the core may comprise side protrusions on the connecting surfaces, the protrusions extending in outward directions relative to the central plane of the core.

[0009] The technical problem is further solved by a ferrite core for an electromagnetic device, the core consisting of two parts, each part having at least two connecting surfaces for connection with the mating part of the core. The core is characterized in that the connecting surfaces of the core parts are beveled, and at least two connecting surfaces are convergent. The proposed core is easy to manufacture and allows increasing the assembling accuracy of the core parts by centering said parts during the core assembly process, as well as reducing and balancing magnetic resistance of the core relative to the central plane of the core due to the increase in the mating connecting surfaces area.

[0010] The technical problem is further solved by a ferrite core for an electromagnetic device, the ferrite core consisting of two parts, each part having at least two connecting surfaces for connection with the mating part of the core, wherein at least one centering protrusion is provided on one connecting surface, and a recess having a shape matching the shape of the protrusion is provided on the other, corresponding, connecting surface, and at least one other connecting surface of each core part is beveled. The core according to this embodiment provides centering by having a protrusion and a corresponding recess on at least one pair of connecting surfaces and by having atleast one other pair of connecting surfaces beveled. The at least one pair of beveled connecting surfaces further provides the decrease in the magnitude of magnetic resistance between the core parts due to the increase in the mating surfaces area.Brief Description of the Drawings[Oi l] The present invention will now be described in more detail with reference to the accompanying drawings, in which:

[0012] FIG. 1 shows an embodiment of a ferrite core for an electromagnetic device (inductor or transformer core), the core consisting of two E- shaped parts, each part comprising three connecting surfaces, wherein the centering protrusion and the recess are provided only on the central connecting surfaces (center core element);

[0013] FIG. 2 shows an embodiment of the ferrite core for an electromagnetic device (inductor or transformer core), the core consisting of two E-shaped parts, each part comprising three connecting surfaces, wherein the centering protrusion and the recess are provided on all connecting surfaces (center core element and side core elements);

[0014] FIG. 2A shows a particular embodiment of the core shown in FIG. 1, wherein side protrusions are formed on the side core elements of the core;

[0015] FIG. 3 shows an embodiment of the ferrite core for an electromagnetic device (inductor or transformer core), the core consisting of two U-shaped parts, each part comprising two beveled and converging connecting surfaces;

[0016] FIG. 3A shows a particular embodiment of the core shown in FIG. 3, wherein all connecting surfaces are beveled in different directions;

[0017] FIG. 4 shows an embodiment of a ferrite core for an electromagnetic device (inductor or transformer core), the core consisting of two E-shaped parts, each part comprising three connecting surfaces, wherein the protrusion and the recess are provided on the central connecting surfaces (center core element), and the connecting surfaces of the side core elements are beveled and converging in opposite directions.Detailed Description of the Invention

[0018] FIG. 1 shows a ferrite core 1 for an inductor or transformer consisting of two E-shaped parts 2a and 2b, each part having two side core elements and one center core element. Part 2a of the core 1 comprises three connecting surfaces 4aa, 4ba, 4ca for connecting with the connecting surfaces 4ab, 4bb, 4cb, respectively, of the mating part 2b of the core 1. A centering protrusion 5bb is provided on the central connecting surface 4bb of the core part 2b, and a recess 5ba is provided inthe corresponding connecting surface 4ba of the other core part 2a, the shape of the recess matching the shape of protrusion 5bb.

[0019] The centering protrusion provides centering of the core parts 2a and 2b when coupled relative to the central plane of the core extending transversely relative to the core through the center of the center core element (indicated with a dashed line in FIG. 1), and matching shapes of the protrusion 5bb and the recess 5ba eliminate gaps between the connecting surfaces during centering. Without this protrusion, inaccurate alignment of core parts may occur during core assembly process. In this case, significant magnetic field inhomogeneities will occur near the side core element edges of the core being coupled. As a result of centering, interference and pickup in smallsignal transformers are reduced during core operation. Further, forming of the protrusion 5bb and the corresponding recess 5ba provides an increase in mating surface area of the core parts, which in turn decreases and balances magnetic resistance of the core.

[0020] In the core shown in FIG. 1, several protrusions 5bb may further be provided on the connecting surface 4bb, and a corresponding number of recesses 5ba may be provided on another, corresponding, connecting surface 4ba. According to the present invention, the number and shape of the protrusions may vary, as will be indicated below. However, the protrusions and the corresponding recesses should be arranged in such a way that when the core parts are connected, centering of the core parts relative to the central plane of the core is provided.

[0021] As seen in FIG. 1, the centering protrusion 5bb and the recess 5ba are formed such that flat portions 6a and 6b are arranged on the connecting surfaces 4bb and 4ba around the centering protrusion 5bb and the recess 5ba. The portion 6b ensures the strength of the center core element of the part 2a of the core 1. In case of insufficient area of the flat portion 6b of the edge of the center core element, the parts 2a can be damaged or broken during core assembly process; therefore, the area of the flat portion 6b should be selected to ensure sufficient strength of the center core element of the core parts. A flat portion 6a is further provided on the mating surface 4bb around the recess, the flat portion 6a abutting the portion 6b during core assembly process.

[0022] FIG. 2 shows another embodiment of the disclosed core exemplified by a ferrite core 1 for a transformer, the core consisting of two E-shaped parts 2a and 2b, each part having two side core elements and one center core element. Part 2a of the core 1 comprises three connecting surfaces 4aa, 4ba, 4ca for connecting with the connecting surfaces 4ab, 4bb, 4cb, respectively, of the mating part 2b of the core 1. Centering protrusions 5ab, 5bb, 5cb are provided on each of the connecting surfaces 4ab, 4bb and 4cb of the core, respectively, and mating recesses 5aa, 5ba, 5ca are provided on each corresponding connecting surface 4aa, 4ba, 4ca, the shape of the recesses matching the shape of the protrusions. Providing centering protrusions and recesses on several pairsof the connecting surfaces allows to simplify the core assembly process while ensuring centering of the core parts being coupled relative to the central plane of the core, the central plane extending transversely relative to the core through the center of the center core element (indicated with a dashed line), and further increases the mating area of the side core elements. As a result, magnetic resistance of the core relative to the center core element is reduced and balanced, i.e. approximately equal magnetic resistance on the side core elements and the central core element of the core is ensured.

[0023] The protrusions and recesses may have any stereometric shape, e.g., without limitation, a hemisphere, a cone, a truncated cone, a cylinder, a prism, a pyramid, a truncated pyramid, etc. The recesses and protrusions in the shape of a prism, a pyramid, or a truncated pyramid further allow to prevent the core from rotating, and to provide centering along two axes (relative to the X and Y axes). For example, in the case of a centering protrusion and a recess having a pyramid shape, after coupling the core parts, they are centered in the horizontal plane along the X and Y axes and are prevented from rotating around the central axis (Z axis). Providing the centering protrusion and the recess in the shape of a hemisphere, however, allows the core to rotate around the vertical axis, which may be useful in some applications.

[0024] The core may comprise side protrusions 7a and 7b on the side core elements of the parts 2a, 2b, the protrusions extending in the outward directions relative to the central plane of the core, as shown in FIG. 2A. Side protrusions 7a and 7b are formed such that when the core portions 2a, 2b are coupled, each of the side protrusions 7a is coupled with its corresponding side protrusion 7b. The side protrusions reduce and balance magnetic resistance of the core relative to the central plane of the core extending through the center core element.

[0025] Despite the fact that in the embodiments of the core described with reference to FIG. 1, 2 and 2A, each part of the core comprises three connecting surfaces for connection with the mating part of the core, it will be understood by those skilled in the art that the number of connecting surfaces may differ from that indicated in the described preferred embodiment. For instance, in the absence of a center core element, the number of connecting surfaces for each part of the core is two, and if two center core elements are provided, the number of connecting surfaces for each part of the core is four. Further, several protrusions and corresponding recesses may be provided on each pair of mating connecting surfaces, provided that the shapes of the protrusions and the corresponding recesses match each other as described above. All of the described embodiments are covered by the claims defining the scope of protection claimed in the present patent application.

[0026] FIG. 3 shows a ferrite core 1 for an electromagnetic device, such as an inductor or a transformer, the core consisting of two U-shaped parts 2a and 2b, each part comprising two coreelements with two connecting surfaces 4aa, 4ba and 4ab, 4bb, respectively, for connection with the mating part of the core. The connecting surfaces 4aa, 4ab and 4ba, 4bb are beveled and converging in opposite directions, i.e. the beveled surfaces 4aa, 4ab of the first pair of core elements contacting each other during core assembly process extend towards the second pair of core elements contacting each other during core assembly process, and the beveled surfaces 4ba, 4bb of said second pair of core elements extend towards said first pair of core elements.

[0027] According to the illustrated embodiment, the angles at which the surfaces 4aa, 4ab, and 4ba, 4bb are beveled, representing the angles between the vertical plane and the corresponding connecting surface, are all equal, wherein, as the angles are equal, the connecting surfaces 4aa, 4ab mirror the connecting surfaces 4ba, 4bb relative to the central plane of the core extending transversely relative to the core through its center (illustrated with a dashed line). Providing beveled connecting surfaces as described above ensures centering during core assembly process and increases the area of the mating connecting surfaces, which, in turn, results in decreasing and balancing of magnetic resistance of the core as described above.

[0028] In a particular embodiment, each of the two parts of the ferrite core may comprise more than two beveled connecting surfaces for connection with the mating part of the core. FIG. 3A shows another embodiment of the ferrite core 1 for an electromagnetic device, such as an inductor or a transformer, the core consisting of two E-shaped parts 2a and 2b, each part comprising three core elements with three connecting surfaces 4aa, 4ba, 4ca and 4ab, 4bb, 4cb, respectively, for connection with the mating part of the core. Each of said connecting surfaces is beveled in different directions, as shown in FIG. 3A. This embodiment of the core, due to such mutual arrangement of the beveled surfaces of the core elements, provides centering of the core parts relative to the central plane of the core, and an increase in the mating connecting surfaces area, and further stabilizes the core in all degrees of freedom when the core parts are coupled, except for vertical displacement.

[0029] FIG. 4 shows a ferrite core 1 for an inductor or transformer consisting of two E-shaped parts 2a and 2b, each part having two side core elements and one center core element. Part 2a of the core 1 comprises three connecting surfaces 4aa, 4ba, 4ca for connecting with the connecting surfaces 4ab, 4bb, 4cb, respectively, of the mating part 2b of the core 1. A centering protrusion 5bb is provided on the central connecting surface 4bb of the core part 2b, and a recess 5ba is provided in the corresponding connecting surface 4ba of the other core part 2a, the shape of the recess matching the shape of the protrusion 5bb. As described above, more than one protrusion may be provided.

[0030] Connecting surfaces 4aa, 4ab and 4ca, 4cb are beveled and converging in opposite directions as described above. The beveling angles of the surfaces 4aa, 4ab and 4ca, 4cb representing the angles between the vertical plane and the corresponding connecting surface are allequal, and, therefore, the connecting surfaces 4aa, 4ab mirror the connecting surfaces 4ca, 4cb relative to the central plane of the core extending transversely relative to the core through the center of the center core element (illustrated with a dashed line). This embodiment further provides centering during core assembly process and the increase in the mating connecting surfaces area, which reduces and balances magnetic resistance of the core as described above.Reference numerals used in the description and in the drawings:1 - ferrite core for electromagnetic device;2a, 2b - parts of the core;4aa, 4ab, 4ba, 4bb, 4ca, 4cb - connecting surfaces;5aa, 5ba, 5ca - recesses;5ab, 5bb, 5cb - centering protrusions;6a, 6b - flat portion;7a, 7b - side protrusions.

Claims

CLAIMS1. A ferrite core for an electromagnetic device, the core consisting of two parts, each part having at least two connecting surfaces for connection with the mating part of the core, characterized in that at least one centering protrusion is provided on at least one connecting surface, and a recess is provided in the other, corresponding, connecting surface, the shape of the recess is configured to match the shape of the protrusion.

2. The core according to claim 1, wherein the core parts have a center core element and side core elements, each having a connecting surface, wherein at least one centering protrusion is provided on one connecting surface of each side core element, and a recess matching the protrusion is provided on the other, corresponding, connecting surface of the side core element.

3. The core according to any one of claims 1-2, wherein the at least one centering protrusion and the recess corresponding thereto are provided on all connecting surfaces.

4. The core according to any one of the preceding claims, wherein the at least one centering protrusion and the recess corresponding thereto are shaped as a hemisphere, a cone, a truncated cone, a cylinder, a prism, a pyramid, or a truncated pyramid.

5. The core according to any one of the preceding claims comprising side protrusions on the connecting surfaces, the side protrusions extending in outward directions relative to the central plane of the core.

6. A ferrite core for an electromagnetic device, the core consisting of two parts, each part having at least two connecting surfaces for connection with the mating part of the core, characterized in that the connecting surfaces of the core parts are beveled, and at least two connecting surfaces are convergent in opposite directions.

7. A ferrite core for an electromagnetic device, the core consisting of two parts, each part having at least two connecting surfaces for connection with the mating part of the core, characterized in thatat least one centering protrusion is provided on at least one connecting surface, and a recess is provided in the other, corresponding, connecting surface, the shape of the recess is configured to match the shape of the protrusion, and at least one other connecting surface of each core part is beveled.

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