GB1591162A - Ferro-magnetic core - Google Patents
Ferro-magnetic core Download PDFInfo
- Publication number
- GB1591162A GB1591162A GB31467/76A GB3146776A GB1591162A GB 1591162 A GB1591162 A GB 1591162A GB 31467/76 A GB31467/76 A GB 31467/76A GB 3146776 A GB3146776 A GB 3146776A GB 1591162 A GB1591162 A GB 1591162A
- Authority
- GB
- United Kingdom
- Prior art keywords
- core
- ferro
- insulating material
- magnetic core
- skin
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/24—Magnetic cores
- H01F27/25—Magnetic cores made from strips or ribbons
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Coils Or Transformers For Communication (AREA)
- Insulating Of Coils (AREA)
Description
(54) AN IMPROVED FERRO-MAGNETIC CORE
(71) We, TELCON METALS LIMITED, a British Company; of Manor Royal, Crawley, Sussex, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
This invention relates to ferro-magnetic cores of the kind which provide at least one flux path with or without an air gap and which carry at least one electrical coil.
The invention is especially, but not exclusively, concerned with single ring ferromagnetic cores, that is single "window" cores, formed either by convolutely winding a strip of ferro-magnetic material into a plurality of superimposed turns or by assembling a plurality of apertured discs of circular or non-circular cross-section of ferro-magnetic material in a stack. In the manufacture of single ring ferro-magnetic cores, and in some circumstances in the manufacture of ferro-magnetic cores of other kinds, the core is generally provided with a protective covering to prevent mechanical damage and shorting of turns when the electrical coil to be carried by the core is formed in situ by winding a plurality of turns of wire around at least a part of the covered core.This protective coyering is usually either a preformed rigid box into which the core is placed or a coating of plastics insulating material applied directly to the core. In the latter case, there is a risk that the thickness of the overall coating of plastics insulating material at the boundary edges of the core around which the wire is wound is so thin that a part of an edge of the ferro-magnetic core might be exposed and contact take place between this exposed part of the edge and the wire.
The present invention provides an improved ferro-magnetic core in which this risk is substantially reduced.
In the ferro-magnetic core in accordance with the invention, the boundary edges of at least that part of the core around which wire is to be wound to form an electrical coil are each protected by a rib of insulating material which upstands from one of two surfaces of the core that meet to define said edge and extends beyond said edge and over an adjacent part of the other of said surfaces.
Preferably, at least each of the surfaces of the core which lie in planes normal to the longitudinal axis of the core has a coating of insulating material which extends beyond each boundary edge and over an adjacent part of an adjoining surface of the core and which is of such a thickness as to form, at each of the boundary edges of the surface, a protective rib of insulating material effectively upstanding from said adjoining surface.
In a preferred embodiment of the invention a ferro-magnetic core has an overall skin of insulating material and the skincovered surfaces of the core which lie in planes normal to the longitudinal axis of the core each has an overlying coating of insulating material which is substantially thicker than the underlying insulating skin and which extends beyond each boundary edge and over an adjacent part of an adjoining skin-covered surface of the core, thereby to form a protective rib of insulating material effectively upstanding from said adjoining surface.
Preferably, the insulating material of the protective ribs, of the coatings and, when present, of the underlying skin is a plastics material which can be applied in powdered form to a heated surface or heated surfaces of the ferro-magnetic core or which can be deposited on a surface or surfaces of the core in the form of electrostatically charged particles. Suitable plastics insulating materials include filled or unfilled epoxy resins.
The thickness of the coating of insulating material on each of the surfaces of the core which lie in planes normal to the longitudinal axis of the core preferably lies in the range 0.2 mm to 2.0 mm. Where the core is enveloped in an overall skin of insulating material, preferably the skin has a thickness lying in the range 0.025 mm to 0.25 mm.
Preferably, each protective rib upstands from said other surface or said adjoining surface of the core by a distance lying in the range 0.2 mm to 2.0 mm.
It will be appreciated that since each boundary edge of the ferro-magnetic core, or of at least that part of the core on which an electrical coil is to be wound, is protected by an upstanding rib of plastics insulating material or of other insulating material, the risk that an edge of the ferro-magnetic core might be exposed and contact take place between this exposed part of the edge and the wire of an electrical coil is substantially reduced.
A method of and apparatus for providing a boundary edge of a ferro-magnetic core with a protective rib of insulating material is the subject of co-pending British Patent
Application No. 31466/76 (Serial No.
1 591 161) filed on the same day as the present application.
The invention is further illustrated by a description, by way of example, of a preferred ferro-magnetic core with reference to the accompanying drawing, in which: Figure 1 is a perspective view of the uncoated ferro-magnetic core;
Figure 2 is a broken perspective view of the core after an overall skin of plastics material has been applied;
Figure 3 is a broken perspective view of the core after coatings of plastics material have been applied to the end faces of the core, and
Figure 4 is a cross-sectional perspective view of the coated core shown in Figure 3, drawn on an enlarged scale.
Referring to the drawing, the ferromagnetic core 1 is formed by convolutely winding a strip 2 of ferro-magnetic material into a plurality of superimposed turns. The inner and outer diameters of the core 1, respectively, are 16.5 mm and 27.5 mm and the core has an axial thickness of 6.35 mm.
An overall skin 3 of epoxy resin is applied over the core, the skin having a thickness of 0.1 mm. To each end face of the skin-covered core 1 is applied a coating 4 of epoxy resin which extends beyond the inner and outer boundary edges and on adjacent parts of the adjoining skin-covered inner and outer circumferential surfaces 5 and 6 of the core to form, along each boundary edge, a protective rib 7 which effectively upstands from the circumferential surfaces 5 and 6. Each coating 4 has a thickness of about 0.5 mm and each protective rib 7 upstands from the inner or outer circumferenial surfaces 5 and 6 for a distance of 0.6 mm.
The protective ribs 7 serve to reduce sub stantially the risk that any part of these boundary edges might be exposed and make contact with wire when wire is wound around a part of the core to form an electrical coil.
WHAT WE CLAIM IS:
1. A ferro-magnetic core wherein the boundary edges of at least part of the core around which wire is to be wound to form an electrical coil are each protected by a rib of insulating material which upstands from one of two surfaces of the core that meet to define said edge and extends beyond said edge and over an adjacent part of the other of said surfaces.
2. A ferro-magnetic core wherein at least each of the surfaces of the core which lie in planes normal to the longitudinal axis of the core has a coating of insulating material which extends beyond each boundary edge and over an adjacent part of an adjoining surface of the core and which is of such a thickness as to form, at each of the boundary edges of the surface, a protective rib of insulating material effectively upstanding from said adjoining surface.
3. A ferro-magnetic core having an overall skin of insulating material, wherein at least each of the skin-covered surfaces of the core which lie in planes normal to the longitudinal axis of the core has an overlying coating of insulating material which is substantially thicker than the underlying insulating skin and which extends beyond each boundary edge and over an adjacent part of the adjoining skin-covered surface to form, at each of the boundary edges of the surface, a protective rib of insulating material effectively upstanding from said adjoining skin-covered surface.
4. A ferro-magnetic core as claimed in
Claim 3 wherein the overall skin has a thickness lying in the range 0.025 mm to 0.25 mm.
5. A ferro-magnetic core as claimed in any one of Claims 2 to 4, wherein the thickness of the coating of insulating material on each of the surfaces which lie in planes normal to the longitudinal axis of the core lies in the range 0.2 mm to 2.0 mm.
6. A ferro-magnetic core as claimed in any one of the preceding Claims, wherein each protective rib upstands from said other or said adjoining surface of the core by a distance lying in the range 0.2 mm to 2.0 mm.
7. A ferro-magnetic core as claimed in any one of the preceding Claims, wherein the insulating material of the protective ribs, of the coatings and, when present, of the overall skin is a plastics material.
8. A ferro-magnetic core as claimed in any one of the preceding Claims, wherein the core is a convolute winding of a strip of ferro-magnetic material.
9. A ferro-magnetic core as claimed in
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (10)
1 591 161) filed on the same day as the present application.
The invention is further illustrated by a description, by way of example, of a preferred ferro-magnetic core with reference to the accompanying drawing, in which: Figure 1 is a perspective view of the uncoated ferro-magnetic core;
Figure 2 is a broken perspective view of the core after an overall skin of plastics material has been applied;
Figure 3 is a broken perspective view of the core after coatings of plastics material have been applied to the end faces of the core, and
Figure 4 is a cross-sectional perspective view of the coated core shown in Figure 3, drawn on an enlarged scale.
Referring to the drawing, the ferromagnetic core 1 is formed by convolutely winding a strip 2 of ferro-magnetic material into a plurality of superimposed turns. The inner and outer diameters of the core 1, respectively, are 16.5 mm and 27.5 mm and the core has an axial thickness of 6.35 mm.
An overall skin 3 of epoxy resin is applied over the core, the skin having a thickness of 0.1 mm. To each end face of the skin-covered core 1 is applied a coating 4 of epoxy resin which extends beyond the inner and outer boundary edges and on adjacent parts of the adjoining skin-covered inner and outer circumferential surfaces 5 and 6 of the core to form, along each boundary edge, a protective rib 7 which effectively upstands from the circumferential surfaces 5 and 6. Each coating 4 has a thickness of about 0.5 mm and each protective rib 7 upstands from the inner or outer circumferenial surfaces 5 and 6 for a distance of 0.6 mm.
The protective ribs 7 serve to reduce sub stantially the risk that any part of these boundary edges might be exposed and make contact with wire when wire is wound around a part of the core to form an electrical coil.
WHAT WE CLAIM IS:
1. A ferro-magnetic core wherein the boundary edges of at least part of the core around which wire is to be wound to form an electrical coil are each protected by a rib of insulating material which upstands from one of two surfaces of the core that meet to define said edge and extends beyond said edge and over an adjacent part of the other of said surfaces.
2. A ferro-magnetic core wherein at least each of the surfaces of the core which lie in planes normal to the longitudinal axis of the core has a coating of insulating material which extends beyond each boundary edge and over an adjacent part of an adjoining surface of the core and which is of such a thickness as to form, at each of the boundary edges of the surface, a protective rib of insulating material effectively upstanding from said adjoining surface.
3. A ferro-magnetic core having an overall skin of insulating material, wherein at least each of the skin-covered surfaces of the core which lie in planes normal to the longitudinal axis of the core has an overlying coating of insulating material which is substantially thicker than the underlying insulating skin and which extends beyond each boundary edge and over an adjacent part of the adjoining skin-covered surface to form, at each of the boundary edges of the surface, a protective rib of insulating material effectively upstanding from said adjoining skin-covered surface.
4. A ferro-magnetic core as claimed in
Claim 3 wherein the overall skin has a thickness lying in the range 0.025 mm to 0.25 mm.
5. A ferro-magnetic core as claimed in any one of Claims 2 to 4, wherein the thickness of the coating of insulating material on each of the surfaces which lie in planes normal to the longitudinal axis of the core lies in the range 0.2 mm to 2.0 mm.
6. A ferro-magnetic core as claimed in any one of the preceding Claims, wherein each protective rib upstands from said other or said adjoining surface of the core by a distance lying in the range 0.2 mm to 2.0 mm.
7. A ferro-magnetic core as claimed in any one of the preceding Claims, wherein the insulating material of the protective ribs, of the coatings and, when present, of the overall skin is a plastics material.
8. A ferro-magnetic core as claimed in any one of the preceding Claims, wherein the core is a convolute winding of a strip of ferro-magnetic material.
9. A ferro-magnetic core as claimed in
any one of Claims 1 to 7, wherein the core is a stack of apertured discs of circular or non-circular cross-section of ferro-magnetic material.
10. A ferro-magnetic core substantially as hereinbefore described with reference to and as shown in the accompanying drawing.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA00774496A ZA774496B (en) | 1977-07-28 | 1977-07-25 | An improved ferro-magnetic core |
| GB31467/76A GB1591162A (en) | 1977-07-28 | 1977-07-28 | Ferro-magnetic core |
| IT5047977A IT1079398B (en) | 1977-07-28 | 1977-07-28 | Ferromagnetic core with protected boundary edges - has insulating lip extending beyond one of two surfaces which meet to define edge onto adjacent part of other surface |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB31467/76A GB1591162A (en) | 1977-07-28 | 1977-07-28 | Ferro-magnetic core |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1591162A true GB1591162A (en) | 1981-06-17 |
Family
ID=10323526
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB31467/76A Expired GB1591162A (en) | 1977-07-28 | 1977-07-28 | Ferro-magnetic core |
Country Status (3)
| Country | Link |
|---|---|
| GB (1) | GB1591162A (en) |
| IT (1) | IT1079398B (en) |
| ZA (1) | ZA774496B (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2518305A1 (en) * | 1981-12-11 | 1983-06-17 | Westinghouse Electric Corp | AMORPHOUS METAL CORE WITHOUT SEAL FOR ELECTRIC INDUCTION APPARATUS |
| GB2165082A (en) * | 1984-09-28 | 1986-04-03 | Alps Electric Co Ltd | Magnetic head |
| GB2165081A (en) * | 1984-09-28 | 1986-04-03 | Alps Electric Co Ltd | Magnetic head |
| EP0251321A1 (en) * | 1986-07-04 | 1988-01-07 | Hitachi, Ltd. | Iron core of electromagnet and method of producing the same |
| AT385370B (en) * | 1982-08-31 | 1988-03-25 | Licentia Gmbh | PROTECTIVE TUB FOR RING CORES |
-
1977
- 1977-07-25 ZA ZA00774496A patent/ZA774496B/en unknown
- 1977-07-28 GB GB31467/76A patent/GB1591162A/en not_active Expired
- 1977-07-28 IT IT5047977A patent/IT1079398B/en active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2518305A1 (en) * | 1981-12-11 | 1983-06-17 | Westinghouse Electric Corp | AMORPHOUS METAL CORE WITHOUT SEAL FOR ELECTRIC INDUCTION APPARATUS |
| AT385370B (en) * | 1982-08-31 | 1988-03-25 | Licentia Gmbh | PROTECTIVE TUB FOR RING CORES |
| GB2165082A (en) * | 1984-09-28 | 1986-04-03 | Alps Electric Co Ltd | Magnetic head |
| GB2165081A (en) * | 1984-09-28 | 1986-04-03 | Alps Electric Co Ltd | Magnetic head |
| EP0251321A1 (en) * | 1986-07-04 | 1988-01-07 | Hitachi, Ltd. | Iron core of electromagnet and method of producing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| ZA774496B (en) | 1978-06-28 |
| IT1079398B (en) | 1985-05-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |