EP1288976A1 - Noyau ferromagnétique, en particulier pour transformateurs ou similaires, et son procédé de fabrication - Google Patents

Noyau ferromagnétique, en particulier pour transformateurs ou similaires, et son procédé de fabrication Download PDF

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Publication number
EP1288976A1
EP1288976A1 EP01830558A EP01830558A EP1288976A1 EP 1288976 A1 EP1288976 A1 EP 1288976A1 EP 01830558 A EP01830558 A EP 01830558A EP 01830558 A EP01830558 A EP 01830558A EP 1288976 A1 EP1288976 A1 EP 1288976A1
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EP
European Patent Office
Prior art keywords
laminations
lamination
core
pack
longitudinal edges
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.)
Withdrawn
Application number
EP01830558A
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German (de)
English (en)
Inventor
Pasquale Forte
Francesco Gariboldi
Gianluca Bertocchi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eldor Corporation SpA
Original Assignee
Eldor Corporation SpA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Eldor Corporation SpA filed Critical Eldor Corporation SpA
Priority to EP01830558A priority Critical patent/EP1288976A1/fr
Publication of EP1288976A1 publication Critical patent/EP1288976A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/12—Ignition, e.g. for IC engines
    • 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
    • H01F27/245—Magnetic cores made from sheets, e.g. grain-oriented
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0206—Manufacturing of magnetic cores by mechanical means
    • H01F41/0233—Manufacturing of magnetic circuits made from sheets

Definitions

  • the present invention relates to a nucleus or core of ferromagnetic material, particularly for transformers and similar apparatus and to a process for manufacturing the same, the nucleus being of the type made up of a pack of laminations joined together in an irremovable manner and comprising a side surface consisting at least partly of longitudinal edges of said laminations and designed to be surrounded by the coaxial windings of a transformer.
  • cores of ferromagnetic material are used in transformers for insertion in the primary and secondary windings of the latter to reduce leakage of the magnetic flux as much as possible.
  • cores have an elongated shape i.e. they are substantially made up of an element in the form of a rectilinear bar comprising a side surface designed to be surrounded, possibly by interposition of an appropriate insulating sheath (or the like), by the primary and secondary windings.
  • the empty space at the inside of the winding which is close to the core should be filled with ferromagnetic material as much as possible.
  • the core is required to have a side surface substantially conforming in shape to the inner surface of the coil surrounding it.
  • a first known technique involves use of cores obtained by die-casting of composite materials, i.e. consisting of particles of ferromagnetic material and a binder. These cores however, while enabling the conformation of the windings at the inside of which they are fitted to be followed in a precise manner, have a drawback, i.e. they do not possess crystals of ferromagnetic material suitably oriented in the direction of the magnetic flux and therefore do not enable achievement of a high performance in the transformer operation.
  • each core is made up of a pack of laminations obtained by a rolling operation in the direction that the magnetic flux must have.
  • the laminations are cut to the required length for the core but with different widths so that they can be superposed to form a pack the cross section of which widens in the middle and gets narrower at the two external laminations in order to be able to obtain a contour surface most approaching a cylindrical shape like that of the space into which it is to be inserted.
  • the laminations are jointed together in an irremovable manner by welding or other connection processes.
  • cores obtained following the above described technique have a side surface at the longitudinal edges of the laminations which has a discontinuous conformation since it is made up of the steps formed by the sharp corners of the longitudinal edges themselves.
  • Said core lamination packs first of all have the drawback that they do not properly match the shape of the inner surface of the winding in which they are to be inserted and therefore, since they do not completely occupy the empty space defined by said winding, they do not allow maximization of the electric performance of the transformer.
  • the cores can be the place where, above all in the presence of high voltages of the windings disposed around them, dangerous discharges occur due to the so-called "point effect" caused by the sharp edges themselves, and therefore the voltage that can be obtained on the secondary winding of the transformer must necessary be limited.
  • the technical task underlying the present invention is to devise a core of ferromagnetic material for transformers and similar apparatus and a process for manufacturing the same which are capable of substantially obviating the mentioned drawbacks.
  • Another important aim of the invention is to devise a process for manufacturing cores of ferromagnetic material made up of lamination packs of quick and cheap accomplishment.
  • the core of ferromagnetic material in accordance with the invention is generally identified by reference numeral 1.
  • Fig. 1 it is laterally surrounded by an insulating sheath 2 around which a first electric winding 3 is disposed followed, more externally, by a second winding 4.
  • Core 1 (an elongated body having a longitudinal axis of substantially I-shaped conformation) is formed of a pack of laminations 5 preferably joined together in an irremovable manner and comprises a side surface 6 at least partly made up of longitudinal edges 5a of said laminations 5.
  • the side surface 6, designed to be surrounded by the coaxial windings 3 and 4 has at least one portion of continuous conformation, i.e. without sharp corners even at the regions 6a formed with the longitudinal edges 5a of the laminations 5.
  • said regions 6a are convex and in the form of an arc of a circle. They connect two opposite flat faces 6b defined by the two externally-disposed laminations.
  • the convex regions 6a seen in cross section show a curved profile, preferably although not necessarily of a constant radius.
  • laminations 5 have curved longitudinal edges 5a; a predetermined number of laminations in succession (but preferably all of them) defining said pack have longitudinal edges contiguously and mutually linked up.
  • each lamination is directly disposed close to and in contact with the corresponding corners of a preceding lamination and of a following lamination.
  • This particular geometric configuration enables the presence of sharp-cornered points or at all events discontinuities in the cross-section profile to be avoided.
  • the present invention contemplates a working possibility not only on the section but also along the longitudinal extension axis of the core.
  • cores tapering in the direction of the longitudinal axis 9 can be obtained, as in the example shown in Fig. 10.
  • engagement means to enable a coherent lamination pack to be obtained; in particular the mutual engagement means will be arranged in such a manner that a tight connection between the laminations forming the pack is allowed.
  • Said engagement means is preferably defined by fitting expansions 7b formed in a lamination 5 and respective coupling seats or recesses 7a formed in the following lamination.
  • the invention also relates to a new process being an integral part of the present patent application as well, and adapted to manufacture cores consisting of lamination packs of the above described type.
  • the process first of all comprises a first arrangement step, consisting in cutting out from a metal sheet for example, a plurality of laminations 5 of any sizes (for example, all having the same width and the same length corresponding to the final length of the core to be manufactured).
  • the process involves a second forming step in which the lamination pack is obtained by superposition and irremovable union of said laminations.
  • the number of the required laminations to be superposed and joined together for reaching the final height of the core depends on the thickness of the metal sheet used.
  • a third shaping step which consists of a working involving material removal from the regions of the side surface of the lamination pack formed with the longitudinal edges 5a of said laminations, so that said regions may take a continuous conformation, i.e. devoid of sharp corners and in the form of an arc of a circle, for example.
  • the second forming step for obtaining the lamination pack is carried out by successive operations on each individual lamination and it consists in superposing each lamination (obviously with the exclusion of the first lamination) on the one previously laid down, clenching to the free face of said lamination, the mating face of the lamination submitted to the connecting operation.
  • clenching of each lamination is obtained by punching of same at least at two points, three points for example, spaced apart from each other and defining corresponding attachment regions 7 (see Fig. 4).
  • Punching at said attachment regions 7 is adapted to plastically deform each individual lamination forming a recess or coupling seat 7a on the free face thereof which corresponds to a fitting expansion 7b to be inserted in the recess of the lamination previously arranged (see Fig. 5).
  • the third step of shaping the side surface 6 of the lamination pack is advantageously carried out by a milling operation consisting of one or more passes oriented in the extension direction of the longitudinal edges 5a of laminations 5 (see Fig. 6; axis direction 9).
  • the milling cutter 8 to be used is preferably a concave-profile cutter and during working it enables the laminations to be pressed against each other preventing them from being submitted to separation forces and also to possible deformations at the edges.
  • the invention achieves important advantages.
  • the cores made up of lamination packs in accordance with the invention enable performance of the transformers for which they are used to be maximized because, first of all, they have an outer side surface substantially conforming in shape to the windings into which they are inserted so that practically at the inside of said windings, regions unfilled with ferromagnetic material do not exist.
  • the conformation continuity of the side surface of the cores in accordance with the invention eliminates the presence of sharp corners and therefore mostly reduces any possibilities of discharges caused by the "point effect", even in the case of very high voltages generated in the windings.
  • the process involves steady assembling of the lamination packs with a mere punching operation, so that production costs and times are very reduced.
  • material removal by milling which operation is suitable to determine shaping of the side surface of the cores, is particularly advantageous because it can be easily adapted, by conveniently changing the tool, to make cores formed of lamination packs having the conformation required for each specific application, for instance with tapering shapes at the ends or any other modification not only of the transverse profile but also of the longitudinal one.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacturing Cores, Coils, And Magnets (AREA)
EP01830558A 2001-08-30 2001-08-30 Noyau ferromagnétique, en particulier pour transformateurs ou similaires, et son procédé de fabrication Withdrawn EP1288976A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP01830558A EP1288976A1 (fr) 2001-08-30 2001-08-30 Noyau ferromagnétique, en particulier pour transformateurs ou similaires, et son procédé de fabrication

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP01830558A EP1288976A1 (fr) 2001-08-30 2001-08-30 Noyau ferromagnétique, en particulier pour transformateurs ou similaires, et son procédé de fabrication

Publications (1)

Publication Number Publication Date
EP1288976A1 true EP1288976A1 (fr) 2003-03-05

Family

ID=8184673

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01830558A Withdrawn EP1288976A1 (fr) 2001-08-30 2001-08-30 Noyau ferromagnétique, en particulier pour transformateurs ou similaires, et son procédé de fabrication

Country Status (1)

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EP (1) EP1288976A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007125009A1 (fr) * 2006-04-26 2007-11-08 Robert Bosch Gmbh Bobine d'allumage, en particulier pour un moteur à combustion interne d'un véhicule automobile

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1208180A (fr) * 1957-12-17 1960-02-22 Smit & Willem & Co Nv Circuit magnétique en tôles feuilletées
DE1244944B (de) * 1963-04-06 1967-07-20 C H F Mueller G M B H Aus Blechen aufgebauter Mantelkern fuer einen Hochspannungstransformator
EP0738831A2 (fr) * 1995-04-21 1996-10-23 Hitachi, Ltd. Bobine d'allumage pour moteur à combustion interne
WO1999016092A1 (fr) * 1997-09-19 1999-04-01 Vacuumschmelze Gmbh Procede et dispositif de fabrication de paquets formes de lames de toles pour noyaux magnetiques
EP0953995A1 (fr) * 1998-04-30 1999-11-03 Robert Bosch Gmbh Bobine d'allumage avec noyau en forme de barre
US5986532A (en) * 1996-05-29 1999-11-16 Aisan Kogyo Kabushiki Kaisha Ignition coil for an internal combustion engine

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1208180A (fr) * 1957-12-17 1960-02-22 Smit & Willem & Co Nv Circuit magnétique en tôles feuilletées
DE1244944B (de) * 1963-04-06 1967-07-20 C H F Mueller G M B H Aus Blechen aufgebauter Mantelkern fuer einen Hochspannungstransformator
EP0738831A2 (fr) * 1995-04-21 1996-10-23 Hitachi, Ltd. Bobine d'allumage pour moteur à combustion interne
US5986532A (en) * 1996-05-29 1999-11-16 Aisan Kogyo Kabushiki Kaisha Ignition coil for an internal combustion engine
WO1999016092A1 (fr) * 1997-09-19 1999-04-01 Vacuumschmelze Gmbh Procede et dispositif de fabrication de paquets formes de lames de toles pour noyaux magnetiques
EP0953995A1 (fr) * 1998-04-30 1999-11-03 Robert Bosch Gmbh Bobine d'allumage avec noyau en forme de barre

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007125009A1 (fr) * 2006-04-26 2007-11-08 Robert Bosch Gmbh Bobine d'allumage, en particulier pour un moteur à combustion interne d'un véhicule automobile
US7834732B2 (en) 2006-04-26 2010-11-16 Robert Bosch Gmbh Ignition coil, in particular for an internal combustion engine of a motor vehicle

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