FR2511184A1 - PROCESS FOR OBTAINING A COIL WITH A CLOSED MAGNETIC CIRCUIT AND A PERMANENT MAGNET FOR THE IGNITION OF AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

COIL CONTAINING A PRIMARY WINDING 1, A SECONDARY WINDING 2 A MAGNETIC CIRCUIT 3 CONSTITUTES STRIPS 4 STACKED ON ONE ON THE OTHERS AND FOLDED SO AS TO FORM A MAGNETIC CIRCUIT IN WHICH IS AVAILABLE A PERMANENT MAGNET 5, CHARACTERIZED IN THAT THE MAGNETIC CIRCUIT 5 3 CONSISTS OF A SINGLE STACK OF STRIPS 4 IS COMPLIANT, BY BENDING FOR ITS CLOSURE ON THE SURFACES S1 OF THE PERMANENT MAGNET 5 AFTER PLACEMENT OF WINDINGS 1 AND 2 ON BRANCH 4B AROUND WHICH THEY ARE ARRANGED.

Description

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  PROCESS FOR OBTAINING A COIL WITH A CLOSED MAGNETIC CIRCUIT AND A

  AIMA Nr PERMANENT FOR THE IGNITION OF INTERNAL COMBUSTION ENGINES.

  The invention relates to a method for obtaining a coil with a closed magnetic circuit and a permanent magnet for the ignition of internal combustion engines, in particular of motor vehicles, coil comprising a primary winding and a secondary winding surrounding at least one of the branches of the magnetic circuit.

  This magnetic circuit consists of strips, sheet metal, different

  length annuities, stacked on top of each other and folded so as to form a closed circuit, without magnetic joint, circuit

  in which is placed a permanent magnet with a larger surface

  as much as the section of said circuit which additionally comprises elements

  flow diversion elements created by primary hoarseness

  We already know, by French patent 1,482,818, an aluminum coil.

  lighting, without permanent magnet, in which the magnetic circuit

  of the closed type, consists of two U-shaped parts made from

  shooting bands, sheet metal, stacked on top of each other.

  In this coil and due to the fact that no provision is made for

  permanent mant, only half of the hysteresis cycle is used which is not advantageous with regard to the volume, therefore the weight of the materials to be used to obtain the

  ignition characteristics of internal combustion engines.

  Also known by the first addition N 0 66 586 of French patent 1 058 103, an ignition coil with a closed magnetic circuit comprising a permanent magnet magnetized in the direction of its

  thickness so that the magnetic flux 4 it generates is op-

  posed to the flow produced by the primary winding of said coil.

  This ignition coil brings a significant improvement, compared to a coil without permanent magnet, due to the fact that the use of a large part of the hysteresis cycle, due to the

  presence of the permanent magnet, reduces dimensions.

  However, one of the drawbacks of this circuit consisting of two U-shaped parts arranged facing each other, is that the magnet being arranged perpendicular to the flow flowing in the circuit,

  any increase in the dimensions of the magnet, except for its thick-

  sor, in order to have a larger magnetic field leads to an increase in the section of the magnetic circuit -2 consisting of U-shaped parts therefore to an increase in volume. Another disadvantage of this circuit is that the performance of the

  coil are partly conditioned by the quality of the magnetic seal

  tick located in the center of the branch surrounded by the primary and secondary windings and at the permanent magnet joint plane magnetic circuit.

  This quality which intervenes in the reluctance of the magnetic circuit

  tick is dependent on differences in thickness of the per-

  now placed opposite the branch surrounded by the windings

  which differences in thickness are inherent in any

mass production.

  In this embodiment and to overcome this drawback, ferromagnetic elements, overlapping said joint, its applied against the U-shaped parts, but this then leads to an increase in the weight of copper consumed: killing the windings, due to the fact that we thus increase the section of the branch which is surrounded

by the windings.

  A magnetic circuit, known per se, overcomes these drawbacks.

  This circuit, consisting on the one hand of sheet metal portions, cut in the shape of L, I and U is assembled so as to form a

  closed circuit with a permanent magnet in the op-

  placed on the branch surrounded by the windings.

  This permanent magnet, magnetized in the direction of its thickness, is arranged in the same way as in French patents 1,041,524

  1 048 081 and German DE A 1 464 202, i.e. not perpetual

  specifically to the section of the magnetic circuit.

  This arrangement increases the surface of the magnet and

  thus the flux emitted by this magnet, without increasing the sec-

  tion of the sheets constituting the magnetic circuit, hence an encom-

brement and reduced weight.

  A flow diversion circuit created by the primary winding,

  circuit of the kind described in French patent 2,168,919, per-

  uses a permanent magnet with a low coercive field, inexpensive and available in large quantities: This branch circuit, in this embodiment, is advantageously made up of plates, made of mild steel sheet,

  arranged, via insulating material, at a distance

  predetermined tance, on either side of the plans defining

25111-84

  the thickness of the branch in which the magnet is placed.

  However, this magnetic circuit has the disadvantage of com-

  wear a magnetic seal arranged, in this example, at an ex-

  end of the branch surrounded by the primary and secondary windings.

  This essential magnetic seal to be able to place the reels

  Lements pre-wound on one of the branches, when these circuits consist of sheets cut in the shape of E, L or U, increases the reluctance of the circuit, which must be compensated by a

  increasing the surface of the permanent magnet by one dimension

  non-optimum operation of the ignition coil.

  The invention overcomes this drawback and to this end relates to a method for knitting a closed circuit coil and

  with permanent magnet, for the ignition of internal combustion engines

  dull, coil having a primary winding and a winding-

  secondary ment surrounding at least one branch of the ma-

  gnetic made up of strips, sheet metal, of different lengths stacked on top of each other and folded so as to form a closed magnetic circuit in which a magnet is placed

  permanent whose Si surfaces are larger than the sec-

  tion 52 of said circuit, ignition coil comprising elements of which a part serves as a bypass of the flux created by the primary winding, characterized in that the magnetic circuit consisting of a single stack of strips of sheet metal, of different lengths, is shaped , by folding, to close it on the Si surfaces of the permanent magnet, after the windings have been placed on

  the branch around which they are arranged.

  The advantage of this process is that the di-

  mensions of the magnetic circuit of the ignition coil to the maximum

  mum compatible with the required ignition characteristics, which makes it possible to reduce the weight of said coil and thus responds

  to the current trend in weight reduction of motor vehicles

  biles in order to reduce fuel consumption.

  The description which follows with reference to the appended drawings will make

  better understand how the invention can be realized.

  FIG. 1 is a longitudinal view in partial section of an ignition coil, according to a first conforming embodiment

to the process of the invention.

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  -4 _ Figure 2 is a side view, in partial section, along the line

  AA, of the ignition coil of figure 1.

  FIG. 3 is a partial view, in longitudinal section, of the branch surrounded by the primary and secondary windings, which in this second embodiment of the method of the invention, is shaped so as to have a substantially circular shape

  in the area surrounded by the windings.

  Figure 4 is an enlarged section of sheets along line AA

in Figure 3.

  Figure 5 is a partial longitudinal view of a coil of al-

  lighting according to a third embodiment of the method of the invention

vention.

  Figure 6 is a partial longitudinal view of an aluminum coil.

  lighting according to a fourth embodiment of the method of the invention

vention.

  FIG. 7 is a partial longitudinal view of an aluminum coil.

  lighting according to a fifth embodiment of the method of the invention

vention.

  According to the present invention, the ignition coil represents

  felt by FIGS. 1 and 2 comprises a primary winding 1 and a secondary winding 2 surrounding a branch of the circuit

  magnetic 3 made up of strips 4 made of mild steel sheet These ban-

  of different lengths are stacked on top of each other with a predetermined longitudinal offset and folded so that

  form a closed magnetic circuit in which is disposed a-

  permanent mant 5 whose Si surfaces are larger than

section 52 of said circuit.

  The ignition coil has flow diversion elements

  created by the primary winding 1, when it is energized.

  These derivation elements are formed in this embodiment

  sation, a flange 6, made of mild steel sheet, which U-shaped flange, has extensions 6 a, 6 b, which allow the fixing of the coil on the motor vehicle

  A screw 7 keeps pressed half-shells against each other.

  the 8 in which the magnetic circuit 3 is enclosed These half shells 8, made of molded insulating material, maintain at a

  predetermined distance d, the metal flange 6, on either side

  be plans defining the thickness E (see figure 2) of the circuit

  magnetic 3, in the area where the permanent magnet 5 is placed.

  The windings 1 and 2 previously wound around insulating supports 9 and 10 (see fig 1) are placed in a box 11, in

plastic material.

  After which and before the operation of coating the windings 1 and 2 in an insulating material filling the housing 11, the junctions

electrical are performed.

  For this purpose, the primary winding 1 and secondary 2 are connected

  by one of their ends to a terminal 12, supply from

  firing of the vehicle's on-board battery (not shown).

  The winding 1 is connected by its other end to a terminal 13 ensuring the connection with a mechanical or electronic breaker (not shown) the winding 2 being connected to a terminal 14 of

secondary voltage output.

  In accordance with the method of the invention, the strips 4 are first folded, at a right angle, using appropriate tools on either side of the casing so as to form a Ut after which the portion 4 a and then portion 4 b are also folded

  at right angles to be applied to surfaces If of the

  permanent mant 5, which at this stage of production is materialized by a removable tool After this folding operation, the magnet

  permanent 5 is positioned in place of the removable tool.

  A first half-shell 8 encloses the magnetic circuit 3 over half of its thickness E, thus maintaining the portions 4 a, 4 b in contact with the surfaces Si of the permanent magnet, after which the second half-shell is positioned. 8, then the flange 6

  the screw 7 now pressed, one against the other, said co-

bowling.

  In a second embodiment (see Figures 3 and 4) the branch

  che 4 b, around which the windings 1 and 2 are arranged

  is shaped to have a substantially circular shape

  area (see fig 4) so as to have a cylindrical area

  on which the primary winding 1 is wound, after interpolation

  sition of an insulating coating between this cylindrical zone and

winding.

  The insulating coating, in this embodiment is made

  dried according to a well known technique which consists in spraying an insulating material, such as an epoxy resin, in the form of powder -6- on the cylindrical zone previously heated. The powder thus applied melts and thus forms a continuous layer of approximately 0, 2-a

0.3 millimeter thick.

  This second embodiment allows, for certain applications,

  tions to improve heat exchange between the magnetic circuit

  tick 3 and primary winding 1, the magnetic circuit is

  front of the heat produced by the winding during

  the ignition coil.

  The substantially circular shape (see fig 4) is obtained after total stacking of the strips 4 and introduction of this stacking of strips, in a suitable device (not shown) comprising a matrix, concave, in two parts and a punch

equal in two parts.

  According to a third embodiment represented by FIG. 5, the strips 4 are in contact with the surfaces SI, of the permanent magnet 5, by means of a transverse camber 16

  made at each end of the strips 4.

  This embodiment allows, if the required characteristics

  authorizes him to dispense with the milling or bro-

  chage, imposed by the first embodiment, embodiment

  tion in which all the biased surfaces obtained by cooling

  wise or pinout are in contact with the SI surfaces of the magnet

  permanent, eliminating parasitic air gaps.

  According to a fourth embodiment, represented by FIG. 6, the inner strip 4 d and the outer strip 4 e have a length such that, after folding, they respectively cover one of the surfaces Si of the permanent magnet 5 and that they are in touch with

  other bands by the transverse edge 17 of said bands.

  According to a fifth embodiment, represented by FIG. 7, the strips 4 have a length such that, after folding, the internal strip 4 d and the external strip 4 e respectively cover one of the surfaces Si of the permanent magnet 5, the other bands 4 not covering, with respect to the interior 4 d and exterior bands

  4th, that a fraction of the previous bands.

  Advantageously, but not necessarily, the permanent magnet 5

  can be positioned, in its longitudinal direction, through

  diary of the inner 4 d and outer 4 e bands, the end of which

  18 is arched at right angles as shown in FIGS 5,6,7.

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Claims (7)

CLAIMS R E V E N D I C A T I O N S closed   1. Method for obtaining a coil, with magnetic circuit and ai-   permanent mount, for the ignition of internal combustion engines, coil comprising a primary winding (1) and a secondary winding (2) surrounding a branch (4 b) of the magnetic circuit (3) consisting of strips (4), made of metal , of different lengths, empi-   tied on top of each other and folded so as to form a circle   magnetic baking in which is placed a permanent magnet (5) whose surfaces 51 are larger than the section 52 of said circuit comprising elements (6 and 8) of which a part serves as a circuit for diverting the flux: created by the primary winding (1)   characterized in that the magnetic circuit, consisting of an empi-   the single strip of strips (4) is shaped, by folding, for its closing   ture on the surfaces 51 of the permanent magnet (5) after setting   place windings (1 and 2) on the branch (4 b) around the- what they are willing.   2. Method according to claim 1, characterized in that the   branch (4 b) around which the windings are arranged -   (1 and 2) is shaped so as to have a shape (15) sensi- definitely circular.   3 Method according to claim 2, characterized in that the substantially circular shape (15) is shaped after empilàgg total of bands (4).   4. Method according to claim 1, characterized in that the   strips (4) are in contact with the surfaces 51 of the permanent magnet   nent (5) by means of a transverse camber (16)   traced at each end of the strips (4).   5. Method according to claim 1, characterized in that the ban-   of inner (4 d) and the outer band (4 e) have a length   such that, after folding, they respectively cover one of the over-   faces 51 of the permanent magnet (5) and that they are in contact   other bands (4) by the transverse edge (17) of said bands.   6. Method according to claim 1, characterized in that the   strips have a length such that, after folding, the inner strip   re (4 d) and the outer strip (4 e) respectively cover one of the surfaces 51 of the permanent magnet (5) the other strips not covering   with respect to the interior and exterior bands (4 d 4 e) that a frac- tion of the previous bands. 8 -   7. Method according to one of claims 4,5,6 characterized in   that the permanent magnet (5) is positioned, in its lon-   gitudinal, via the interior (4 d) and exterior bands   upper (4 e) whose end (18) is arched substantially at right angles.