GB1571057A - Magnetic circuits - Google Patents
Magnetic circuits Download PDFInfo
- Publication number
- GB1571057A GB1571057A GB356377A GB356377A GB1571057A GB 1571057 A GB1571057 A GB 1571057A GB 356377 A GB356377 A GB 356377A GB 356377 A GB356377 A GB 356377A GB 1571057 A GB1571057 A GB 1571057A
- Authority
- GB
- United Kingdom
- Prior art keywords
- beads
- magnetic circuit
- web
- circuit according
- magnetic
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B23/00—Tube-rolling not restricted to methods provided for in only one of groups B21B17/00, B21B19/00, B21B21/00, e.g. combined processes planetary tube rolling, auxiliary arrangements, e.g. lubricating, special tube blanks, continuous casting combined with tube rolling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
- B21K21/00—Making hollow articles not covered by a single preceding sub-group
- B21K21/02—Producing blanks in the shape of discs or cups as semifinished articles for making hollow articles, e.g. to be deep-drawn or extruded
-
- 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
- H01F27/26—Fastening parts of the core together; Fastening or mounting the core on casing or support
- H01F27/263—Fastening parts of the core together
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Mechanical Engineering (AREA)
- Ignition Installations For Internal Combustion Engines (AREA)
Description
(54) IMPROVEMENTS RELATING TO MAGNETIC CIRCUITS
(71) We, SOCIETE ANONYME
POUR L'EQUIPEMENT ELECTRIQUE
DES VEHICULES S.E.V. MARCHAL, a
French Body Corporate, of 26, rue Guynemer 92132 Issy-Les; Moulineaux, France, 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: It is known, in a certain number of magnetic or electromagnetic devices, to use a magnetic circuit comprising one or several components, the median line of said circuit traversing at least one electromagnetic air gap.In general, this air gap is provided between the ends of two distinct components of the circuit, the circuit also comprising connector means permitting fixing of the different elements of the circuit to each other.
Taking account of manufacturing tolerances, it is often very difficult to be sure that the air gaps of these magnetic circuits have well determined precise values. This disadvantage has a repercussion on the functioning of the apparatus incorporating the magnetic circuit in question, for it is known that the value of the air gap of a magnetic circuit, such as that of an ignition coil, has influence upon the magnetic circuit as a whole at the working frequencies. In other words, if the values of the air gap or air gaps vary as a function of working tolerances, the ignition coils have differing characteristics such that the manufacture cannot be sure of selling a series of coils having perfectly reproducible characteristics.
This type of disadvantage is capable of interfering with manufacture of ignition coils which comprise a coil consisting of a practically closed magnetic ring, with small air gaps, where the ring has the primary and secondary windings disposed therearound.
Such coils are already known in the prior art and have been described for example in
French Patent Publication No. 2,321,054. In the embodiment of core described in this
French Patent Specification the magnetic ring is constituted by locating the two elements relative to one another so as to provide the desired air gaps and then by setting the elements in a casting, the air gaps being filled by casting material. In this type of cote the value of the air gaps is in risk of being essentially variable as a function of the posi- tioning of the elements of the ring in the casting mould. Furthermore, at the air gaps dust or metal swarf may inadvertently be included in the cast material and reduce the actual value ob the air gap.As a result there is a chance that use of this type of core, if ap propnate relatively costly precautions are not taken, leads to the production of ignition coils having characteristics which exhibit a by no means negligible variation.
The present invention has as its object the provision of a magnetic circuit having at an air gap a connector component to ensure the constancy of the air gap value and consequently to ensure a considerable reduction in the variation of efficiency characteristics of the devices using the magnetic circuits thus equipped. The magnetic circuit according to the invention is particularly suitable for the provision of ignition coils intended for proW ducing the H.T. electrical discharge necessary for ignition in the combustion chambers of an internal combustion engine. However, the use of the magnetic circuit according to the invention is not solely limited to use in this type of device.
According to the present invention we provide a magnetic circuit including two adjacent pole faces defining a gap; a connector component having a part thereof disposed in the gap, the connector component comprise ing at least two cylindrical beads as herein defined) having their generatrices parallel, these beads being both spaced apart by and integral with a web and being received in grooves in the pole faces so as to hold the parts of the said magnetic circuit from movement which would bring the said pole faces towards or away from each other; and a transverse member which is integral with said web, and is disposed between two beads and lies in said gap, the cross-section of the beads being such that the thickness of said web is less than the maximum dimension of each said bead in a direction transversely of said web.
Throughout the present description, and in the claims, the term "cylindrical bead" is used to denote a bead whose shape is generated by the displacement of a straight line, which remains parallel to a given direction, along a path which may be curvilinear or polygonal.
The connector component may comprise more than two beads and the beads, which are disposed on one end of the web, are on opposite sides of the web. The connector component may, for example, comprise a plurality of beads on each end of the web; but alternatively only a single bead may be provided on each end of the web.
The connector component may suitably be formed of an electrical insulator, and in this way the two parts of the magnetic circuit may serve as electrical terminals when combined by the connector component. The connector component is preferably provided of a moulded plastic material. More preferably at least the said transverse member is pro vided in a material having a high dielectric strength. In a preferred embodiment the said transverse member is a substantially planar plate parallel to the beads of the connector component, and the said substantially planar plate may be disposed in the plane of symmetry perpendicular to the web and parallel to the generatrices of the two beads: the connector component comprises beads which are chamfered at at least one of their ends.
The connector component is symmetrical relative to a plane parallel to the generatrices of the beads and perpendicular to the web which joins the two beads.
The beads of the connector component are intended to be introduced into grooves of a corresponding shape formed in pole faces to be connected thereby.
The positioning of the connector component between the two magnetic circuit parts to be assembled can be effected by any appropriate means, and in particular by force fitting in a press which guides the connector component into place, thereby assuring a firm holding of the beads in the recesses which correspond thereto. Where the said transverse member is a substantially planar plate, it is clear that the thickness of said plate is less than, or at most equal to, the distance between the two pole faces to be assembled. This substantially planar plate may conveniently be positioned between the two said faces and preferably have a shape substantially identical to that defined between the said pole faces which are face-to-face and which define the air gap.The introduction of the substantially planar plate in the air gap at the moment of inserting the connector component permits the exclusion of all dust or swarm which may be found in the said air gap. Clearly, the connector component thus simultaneously ensures precise relative positioning of the magnetic circuit parts which are to be assembled, and also precise and constant control of the air gap provided between the two adjacent parts, without the initial presence of dust or of swarm which may affect the value of the resulting air gap.
The connector component including a sub
stantially planar plate may be obtained in a cheap manner by moulding of plastics material, for example polyamide. Preferably a plastics material is chosen having a good mechanical strength, for permitting ease of positioning of the connector component, and having a good dielectric strength. In the case where the magnetic circuit is to be formed from two L-shaped elements, a connector component according to the invention may advantageously be disposed in each of the two air gaps of the circuit and can thus ensure that the mere positioning of these two connector components will provide a very satin factory mechanical fixirDg of the two L-shaped elements to form a square.As a result, in the case where the magnetic circuit is a rectangular ring used for an ignition coil, without an oil bath, it is no longer obligatory to provide fixing of the elements in a square array by moulding in plastics material, the simple insertion of the connector components will be sufficient for assuring cohesion of the assembly.
It can be seen that the ignition coils of the type described in French Patent Publication
No. 2,321,054, may be provided merely by using two connector components and will present constant magnetic characteristics, thus permitting the control of the air gaps in a manner for obtaining a practically maximum efficiency for all the ignition coils of the same production run.
According to the present invention there is also provided a magnetic or electromagnetic device comprising at least one magnetic circuit as defined above. The device may, for example, be an ignition coil for generating the
H.T. discharge for the ignition of an internal combustion engine.
The fact of using, for each air gap of such an ignition coil, a connector component with an integral plate enables the use, as an electrical connection point, of at least one of the two circuit parts thus joined thereby improving insulation of the coil against voltage surges liable to occur between the two parts of the magnetic core of the coil. It is known that in this type of ignition coil, when the magnetic circuit is formed by the assembly of two L-shaped elements into a square, one can advantageously connect one of the elements to earth and connect the other ele ment electrically to the terminal common to the primary coil and the secondary coil.The presence of plates in the air gaps makes it possible that, when one has chosen for the connector component a plastics material of high dielectric strength, a considerable im provement of insulation can be obtained against voltage surges in the primary windings.
In order that the invention may be better understood there will now be described, purely by way of example, one embodiment represented on the accompanying drawing, in which:
FIGURE 1 shows, in exploded perspective, a magnetic core of an ignition coil for an internal combustion engine, this core being constituted of two L-shaped elements in tended to be connected by the connector components according to the invention; and
FIGURE 2 shows a plan view of the magnetic core of Figure 1, after connection has been achieved by placing the two connector components in position.
Reference to the drawing will show that the magnetic coil there illustrated is a frame of which the median line is substantially square, this frame being intended to be surrounded by a primary coil and by a secondary coil, as has been described, for example, in the said French Patent Publication No.
2,321,054. This magnetic core is constituted by two identical core elements la, ib each having L-shaped form.
Each element la or ib is formed by a stack of plates of magnetisable material.
When the two L-shaped core elements la, ib are brought together for forming a square, as shown in Figure 2, they define between them two air gap zones 3 and 4. In the parts of the core bounding the zones 3 and 4, the core elements la and ib include grooves, 5a and 6a for the core element la, and 5b and 6b for the core element ib. These grooves are of constant cross-section, the shallower part of the groove, constituting a passage having substantially parallel sides whose floor is cut away to open into a recess of right cylindrical form of circular base, said recess having generatrices perpendicular to the median plane of the stack of magnetic plates which constitute the core elements la and ib, and having a diameter greater than the width of the aforementioned passage. When the core elements la and ib are in position, as shown in Figure 2, forming a square magnetic core, the grooves 5a and 5b on the one hand, and 6a and 6b on the other hand, are face-toWface and the passages along which they open to the exterior are situated facing one another. The grooves 5a, 5b, 6a, 6b have exactly the same dimensions as one another.
The connector components 10 for joining the two L-shaped core elements are moulded of a plastics material known under the commercial name "NYLON" which is an electric insulator.
Each connector component comprises two identical cylindrical beads 7 having a subs stantially circular cross-section and a length equal to the height of the stack of plates of which the core element la or ib is formed.
The two beads 7 are joined together by a web 8 of which the median plane includes the axes of the two beads 7. The diameter of the bead 7 is substantially equal to the diameter of the bottoms of grooves 5a, 6a, 5b, 6b. The thickness of the web 8 is substantially equal to the width of the abovementioned groove passages. In the plane relative to which the two beads 7 are symmetrical, this plane being perpendicular to the web 8 and parallel to the axes of the two beads 7, the connector component comprises a transverse member in the form of a plate 9 which is substantially planar and has a thickness slightly less than that of the air gap to be provided in the zones 3 and 4.The length of the plate 9 is equal to the lengths of the beads 7 and of the web 8, and the width of the plate 9 in the direction perpendicular to the plane of the web 8 is equal to the width of the surfaces of the core to be joined, in the said direction.
At the ends of the beads 7 and at the corresponding edges of the web 8 parallel to the plane of the transverse plate 9 there exists a chamfer (not shown in the drawing) at a taper angle of 600. For further facilitating entry of the connector components 10 into the grooves and passages 5a, Sb, 6a, 6b the grooves and passage ends may also be given a 600 tapered chamfer. The plate 9 may be formed of a material which has a high dielectric strength. In this case the whole connector component 10 is formed of such a material, namely NYLON.
The two core elements la and ib, these core elements are placed in position so that they form a square magnetic core as indicated on Figure 2, and then the two beads 7 of a first connector component 10 are intro duced into the grooves 5a, 5b. Simultaneously or subsequently the beads 7 of the other connector component 10 are introduced into the grooves 6a, 6b. The introduction of the com- ponents 10 in the corresponding grooves is facilitated by the non-illustrated chamfers at the ends of the beads 7 and of the web 8.
The beads 7 enter the cylindrical zones of the grooves and the web 8 is received in the passages by which the grooves communicate with the exterior. The positioning of the connector components 10 can be effected by any appropriate means, for example by press fitting. Slight tightening may be provided for permitting the avoidance of any accidental expulsion of the connector component.
Preferably, the connector component can be guided during the start of the press fitting.
During this pressing, the plate 9 arrives in place between the two end faces of the two core elements la and ib. The width of the air gap in the zones 3 and 4 is controlled by the distance between the longitudinal axes of the two beads 7, this distance being of course greater than twice the distance existing between the axis of the one groove Sa, 5b or 6a, 6b and the plane of the associated end face of the core element la or Ib, to be joined.
The square magnetic core, which is thus obtained by assembling the two core elements la and lb, presents a considerable mechanical strength and it is practically impossible to destroy the ensuing assembly even by applying to the core forces several times greater than those to which it will normally be subjected in use. Furthermore, when using this magnetic core for an internal combustion engine ignition coil, the core element ib can be connected to earth and the core element la connected to the common point between the primary windings and the secondary windings of the coil.
The presence of the plates 9 in the air gap zones 3 and 4 permits the improvement of insulation against voltage surges in the primary windings. Furthermore, the plate 9 eliminates from the air gap zones 3 and 4, at the moment of its insertion, all dust or metal swarf which are likely to be found there, such that the resulting air gap will not accidentally and randomly be reduced by the presence of this dust or swarms.
Two air gaps of perfectly determined width are thus provided in the magnetic core, such that one can control the value of this air gap for obtaining optimum magnetic efficiencies. The magnetic characteristics of ignition coils made in this way are thus perfectly reproducible and enable improved magnetic efficiencies to be obtained.
The connector component 10 may be modifled from that illustrated, for example in that more than two beads 7 may be provided.
For example there may be two or more beads 7 on each side of the plate 9, and in one convenient alternative form there may be in all four beads 7, arranged in pairs with two beads 7 arranged symmetrically on either side (i.e. above and below as viewed in Figure 2) of the web 8. The pairs themselves will be spaced symmetrically across the plate 9.
WHAT WE CLAIM IS:- 1. A magnetic circuit including two adjacent pole faces defining a gap; a connector component having a part thereof disposed in the gap, the connector component comprising at least two cylindrical beads (as herein defined) having their generatrices parallel, these beads being both spaced apart by and integral with a web and being received in grooves in the pole faces so as to hold the parts of the said magnetic circuit from movement which would bring the said pole faces towards or away from each other; and a transverse member which is integral with said web, and is disposed. between two beads and lies in said gap, the cross-section of the beads being such that the thickness of said web is less than the maximum dimension of each said bead in a direction transversely of said web.
2. A magnetic circuit according to claim 1, wherein there are more than two such beads, with the beads which are at one end of said webs disposed on opposite sides of the web.
3. A magnetic circuit according to claim 1 or 2, and comprising an equal number of beads on both ends of the web.
4. A magnetic circuit according to claim 3, and comprising a single bead on each end of the web.
5. A magnetic circuit according to claim 4, wherein the connector component is symmetrical relative to a plane which is parallel to the generatrices of the beads and is perpendicular to the web which joins the beads.
6. A magnetic circuit according to any one of claims 1 to 5, wherein the connector component is formed of an electrically insulating material.
7. A magnetic circuit according to claim 6, wherein the connector component is formed of a moulded plastics material.
8. A magnetic circuit according to any one of claims 1 to 7, wherein the said transverse member is provided of a material having a high dielectric strength.
9. A magnetic circuit according to any one of claims 1 to 8, wherein the beads have the same cross-section as each other.
10. A magnetic circuit according to any one of the preceding claims, wherein the said transverse member is a substantially planar plate parallel to the axes of said beads.
11. A magnetic circuit according to claims 4 and 10, wherein said substantially planar plate constituting the said transverse member is disposed on the plane of symmetry perpendicular to the web and parallel to the generatrices of the two beads.
12. A magnetic circuit according to any one of claims 1 to 11, wherein the beads are chamfered at at least one of their ends.
13. A magnetic circuit according to claim 12, wherein the beads have an equal length measured parallel to their generatrices and the web has the same length, the end of the web being chamfered in the zone comprised between the chamfered ends of different beads.
14. A magnetic circuit according to. any one of claims 1 to 13, in the form of a substantially closed circuit.
15. A magnetic circuit substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.
16. A magnetic or electromagnetic device, comprising at least one magnetic circuit according to any one of claims 1 to 15.
17. A device according to claim 16, when
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (18)
1. A magnetic circuit including two adjacent pole faces defining a gap; a connector component having a part thereof disposed in the gap, the connector component comprising at least two cylindrical beads (as herein defined) having their generatrices parallel, these beads being both spaced apart by and integral with a web and being received in grooves in the pole faces so as to hold the parts of the said magnetic circuit from movement which would bring the said pole faces towards or away from each other; and a transverse member which is integral with said web, and is disposed. between two beads and lies in said gap, the cross-section of the beads being such that the thickness of said web is less than the maximum dimension of each said bead in a direction transversely of said web.
2. A magnetic circuit according to claim 1, wherein there are more than two such beads, with the beads which are at one end of said webs disposed on opposite sides of the web.
3. A magnetic circuit according to claim 1 or 2, and comprising an equal number of beads on both ends of the web.
4. A magnetic circuit according to claim 3, and comprising a single bead on each end of the web.
5. A magnetic circuit according to claim 4, wherein the connector component is symmetrical relative to a plane which is parallel to the generatrices of the beads and is perpendicular to the web which joins the beads.
6. A magnetic circuit according to any one of claims 1 to 5, wherein the connector component is formed of an electrically insulating material.
7. A magnetic circuit according to claim 6, wherein the connector component is formed of a moulded plastics material.
8. A magnetic circuit according to any one of claims 1 to 7, wherein the said transverse member is provided of a material having a high dielectric strength.
9. A magnetic circuit according to any one of claims 1 to 8, wherein the beads have the same cross-section as each other.
10. A magnetic circuit according to any one of the preceding claims, wherein the said transverse member is a substantially planar plate parallel to the axes of said beads.
11. A magnetic circuit according to claims 4 and 10, wherein said substantially planar plate constituting the said transverse member is disposed on the plane of symmetry perpendicular to the web and parallel to the generatrices of the two beads.
12. A magnetic circuit according to any one of claims 1 to 11, wherein the beads are chamfered at at least one of their ends.
13. A magnetic circuit according to claim 12, wherein the beads have an equal length measured parallel to their generatrices and the web has the same length, the end of the web being chamfered in the zone comprised between the chamfered ends of different beads.
14. A magnetic circuit according to. any one of claims 1 to 13, in the form of a substantially closed circuit.
15. A magnetic circuit substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.
16. A magnetic or electromagnetic device, comprising at least one magnetic circuit according to any one of claims 1 to 15.
17. A device according to claim 16, when
appendant to claim 10, wherein the beads, the web and the said substantially planar plate have substantially the same length as each other, the dimensions of the larger surfaces of the said substantially planar plate being substantially equal to those of the core surfaces to be joined and the thickness of the said substantially planar plate being less
than or at most equal to the separation be- tween the two pole faces which define the
air gap. ~~~~~~~~~~~~~~~~~~~
18. An ignition coil for providing the H.T.
discharge for the ignition of an internal combustion engine, including an electro magnetic device according to either claim 16 or 17.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7602280A FR2339943A1 (en) | 1976-01-28 | 1976-01-28 | Connector for two magnetic circuit parts - has 2 ribs of nonmagnetic material with cylindrical surfaces held apart by connecting strip leaving air gap(s) |
| DE2605236A DE2605236C2 (en) | 1976-02-11 | 1976-02-11 | Use of a piercer and a die to produce a perforated piece |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1571057A true GB1571057A (en) | 1980-07-09 |
Family
ID=25770031
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB356377A Expired GB1571057A (en) | 1976-01-28 | 1977-01-28 | Magnetic circuits |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB1571057A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0050303A1 (en) * | 1980-10-17 | 1982-04-28 | Kanetsu Kogyo Kabushiki Kaisha | Process for manufacturing magnetic pole assembly |
| EP2209128A1 (en) * | 2009-01-20 | 2010-07-21 | ABB Research Ltd. | Gapped magnet core |
| US8354911B2 (en) | 2009-06-15 | 2013-01-15 | North-West University | Segmented core transformer |
| CN108630404A (en) * | 2017-03-17 | 2018-10-09 | 发那科株式会社 | Iron core |
| US20190013136A1 (en) * | 2017-07-04 | 2019-01-10 | Fanuc Corporation | Reactor and method for production of core body |
-
1977
- 1977-01-28 GB GB356377A patent/GB1571057A/en not_active Expired
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0050303A1 (en) * | 1980-10-17 | 1982-04-28 | Kanetsu Kogyo Kabushiki Kaisha | Process for manufacturing magnetic pole assembly |
| EP2209128A1 (en) * | 2009-01-20 | 2010-07-21 | ABB Research Ltd. | Gapped magnet core |
| WO2010083924A1 (en) * | 2009-01-20 | 2010-07-29 | Abb Research Ltd | Gapped magnet core |
| AU2009337916B2 (en) * | 2009-01-20 | 2013-09-19 | Abb Research Ltd | Gapped magnet core |
| US9627118B2 (en) | 2009-01-20 | 2017-04-18 | Abb Research Ltd. | Gapped magnet core |
| US8354911B2 (en) | 2009-06-15 | 2013-01-15 | North-West University | Segmented core transformer |
| EP2443637B1 (en) * | 2009-06-15 | 2013-04-03 | North-West University | Segmented core transformer |
| CN108630404A (en) * | 2017-03-17 | 2018-10-09 | 发那科株式会社 | Iron core |
| US10707008B2 (en) | 2017-03-17 | 2020-07-07 | Fanuc Corporation | Iron core including first iron core block and second iron core block |
| US20190013136A1 (en) * | 2017-07-04 | 2019-01-10 | Fanuc Corporation | Reactor and method for production of core body |
| US10699838B2 (en) * | 2017-07-04 | 2020-06-30 | Fanuc Corporation | Reactor and method for production of core body |
| US10937587B2 (en) | 2017-07-04 | 2021-03-02 | Fanuc Corporation | Reactor and method for production of core body |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |