EP1887589A1 - Bobine d'allumage - Google Patents

Bobine d'allumage Download PDF

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Publication number
EP1887589A1
EP1887589A1 EP06425582A EP06425582A EP1887589A1 EP 1887589 A1 EP1887589 A1 EP 1887589A1 EP 06425582 A EP06425582 A EP 06425582A EP 06425582 A EP06425582 A EP 06425582A EP 1887589 A1 EP1887589 A1 EP 1887589A1
Authority
EP
European Patent Office
Prior art keywords
core
ignition coil
magnetic circuit
permanent magnet
cladding
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Withdrawn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
EP06425582A
Other languages
German (de)
English (en)
Inventor
Maurizio Colombo
Augusto Guccione
Sesto Roberto Pinna
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.)
Marelli Europe SpA
Original Assignee
Magneti Marelli Holding 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 Magneti Marelli Holding SpA filed Critical Magneti Marelli Holding SpA
Priority to EP06425582A priority Critical patent/EP1887589A1/fr
Publication of EP1887589A1 publication Critical patent/EP1887589A1/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Withdrawn legal-status Critical Current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
    • H01F3/00—Cores, Yokes, or armatures
    • H01F3/10—Composite arrangements of magnetic circuits
    • 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
    • H01F2038/127—Ignition, e.g. for IC engines with magnetic circuit including permanent magnet
    • 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
    • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/38—Auxiliary core members; Auxiliary coils or windings

Definitions

  • the present invention relates to an ignition coil.
  • the present invention regards an ignition coil for triggering combustion in a controlled ignition endothermic engine.
  • a known type of ignition coil comprises: a magnetic circuit including a core, a cladding, and a permanent magnet; a primary electrical circuit wound around the core; and a secondary electrical circuit wound around the core and concatenated with the primary electrical circuit.
  • the core extends principally along one axis, and the cladding extends along an annular closed path about the core and lies substantially in the same plane as the axis of the core.
  • the permanent magnet (also referred to as "preload magnet”) is set along the core and enables variations of magnetic induction in the magnetic circuit of the ignition coil that are greater than the variations of magnetic induction that can be obtained in a magnetic circuit without permanent magnet.
  • preload magnet also referred to as "preload magnet”
  • the permanent magnet displaces the point of rest (at zero current) of the curve so as to enable wide variations of magnetic induction in the linear stretch of the characteristic curve B-H.
  • ignition coils of this type present problems linked to the dimensions of the permanent magnet itself and hence impose limits on the lowering of the point of rest of the curve.
  • the presence of a permanent magnet contributes to the generation of the magnetic field and, at the same time, constitutes an important source of reluctance.
  • the cross section of the permanent magnet understood as the cross section substantially orthogonal to the flux lines of the magnetic field, is correlated to the capacity of magnetization of the permanent magnet itself, whilst the thickness of the permanent magnet, understood as the length of the permanent magnet in the direction of the flux lines of the magnetic field, is correlated to its equivalent reluctance.
  • the optimal solution from the theoretical standpoint would consist in producing a thin permanent magnet provided with a relatively extensive cross section.
  • a relatively thin permanent magnet is subject to frequent breakdowns because the ignition coil is mounted and operates in the engine compartment of a motor vehicle and is consequently subject to particularly critical mechanical stresses (vibrations) and thermal stresses (high temperatures).
  • the limits to the extension of the permanent magnet are substantially dimensional limits because they would require that also the magnetic circuit have a cross section equal to the cross section of the permanent magnet.
  • the permanent magnet has dimensional limits set by the relatively hostile environment in which the ignition coil operates, and consequently the wide variations in magnetic induction required by the market cannot be reached.
  • the limit of saturation of the magnetic circuit is often reached with a consequent sudden increase in the charge currents and in the thermal stress of the component. Consequently, the ignition coil reaches high temperatures that increase the risk of breakdown thereof.
  • An object of the present invention is to provide an ignition coil that will be free from the drawbacks just highlighted of the prior art.
  • an object of the invention is to provide a reliable ignition coil capable of high performance and at the same time easy to produce and at a low cost.
  • the present invention relates to an ignition coil for triggering combustion in a controlled ignition endothermic engine, the ignition coil comprising: a magnetic circuit including a core, a cladding and a first permanent magnet; a primary electrical circuit wound around the core; and a secondary electrical circuit wound around the core and concatenated with the primary electrical circuit; the ignition coil being characterized in that it comprises at least one second permanent magnet, the first and second permanent magnets being set in parallel along the magnetic circuit.
  • FIG. 1 designated by the reference number 1 is an ignition coil for triggering combustion in a controlled ignition endothermic engine and habitually housed in the engine compartment of a motor vehicle.
  • the ignition coil 1 comprises a magnetic circuit 2, a primary electrical circuit 3, and a secondary electrical circuit 4.
  • the magnetic circuit 2 comprises a core 5, which extends principally along an axis A, and a cladding 6, which extends along an annular path about the core 5 in the same plane as the axis A.
  • the primary electrical circuit 3 is wound around the core 5, and the secondary electrical circuit 4 is wound around the core 5 and is concatenated to the primary electrical circuit 3.
  • the arrows indicate the direction of the flux of the magnetic field along the magnetic circuit 2.
  • the flux lines of the magnetic field arise in an area corresponding to the core 5 of the magnetic circuit 2 and branch off on opposite sides along the cladding 6 of the magnetic circuit 2, and then join up again along the core 5 so as to form a characteristic path comprising two closed rings with a branch in common.
  • the magnetic circuit 2 further comprises a first permanent magnet 7 and at least one second permanent magnet 8 set in parallel.
  • the first permanent magnet 7 and the second permanent magnet 8 are set in parallel along the cladding 6.
  • the magnetic circuit 2 is moreover divided into at least one first part 9 and one second part 10.
  • the first part 9 is substantially T-shaped and comprises the core 5 and a head 11, which is fixed to the core 5 and defines a portion of the cladding 6, whilst the second part 10 defines the remaining part of the cladding 6 and has two ends 12 and 13 close to the first part 9 of the magnetic circuit 2.
  • the first permanent magnet 7 and the second permanent magnet 8 are arranged between the first part 9 and the second part 10, respectively, in a position corresponding to the ends 12 and 13 of the second part 10.
  • the core 5 has a face 14, which is set in a direction orthogonal to the axis A in a distal position with respect to the head 11 and at a distance close to a respective face 15 of the second part 10 of the magnetic circuit 2, parallel to the face 14.
  • FIG. 2 shows a second embodiment of the ignition coil 20 according to the present invention. Also in this figure, the arrows illustrated indicate the direction of the flux of the magnetic field.
  • the ignition coil 20 comprises a magnetic circuit 21, a primary electrical circuit 22, and a secondary electrical circuit 23.
  • the magnetic circuit 21 comprises a core 24, which extends principally along an axis B, and a cladding 25, which extends along an annular path about the core 24 in the same plane as the axis B of the core 24.
  • the magnetic circuit 21 further comprises a first permanent magnet 26 and a second permanent magnet 27 set in parallel, which are set in parallel along the cladding 25.
  • the magnetic circuit 21 is divided into a first part 28 and a second part 29.
  • the first part 28 extends substantially along the axis B of the core 24 and comprises the core 24 and a head 30, which is fixed to the core 24 and defines a portion of the cladding 25, whilst the second part 29 defines the remaining part of the cladding 25 and has two ends 31 and 32 close to the first part 28 of the magnetic circuit 21.
  • the first permanent magnet 26 and the second permanent magnet 27 are arranged between the first part 28 and the second part 29 in a position corresponding to the ends 31 and 32 of the second part 29 of the magnetic circuit 21.
  • the core 24 has a face 33, which is set in a direction orthogonal to the axis B in a distal position with respect to the head 30 and at a distance close to a respective face 34 of the second part 29 of the magnetic circuit 21, parallel to the face 33.
  • the first part 28 is able to slide with respect to the second part 29 in a direction substantially parallel to the axis B to enable adjustment of the dimensions of the air gap 35.
  • the head 30 is in contact with the first permanent magnet 26 and the second permanent magnet 27 along surfaces of sliding 36 parallel to one another and parallel to the axis A. Sliding of the first part 28 with respect to the second part 29 along the surfaces of sliding 36 enables adjustment of the distance between the faces 33 and 34 of the air gap 35 during assembly of the ignition coil 20.
  • Figure 3 shows the qualitative evolution of a characteristic curve 37, which represents the magnetic induction B as a function of the magnetizing force H of the magnetic circuit 2 of the ignition coil 1 in which the plates of the magnetic circuit 2 are made of ferromagnetic material.
  • Designated by the reference number 38 is the point of rest, i.e. at zero current, on the hypothesis of a magnetic circuit 2 without permanent magnets.
  • the maximum variation of magnetic induction B allowed with respect to the point of rest is indicated in Figure 3 by ⁇ 1 .
  • Designated by the reference number 39 is the point of rest, i.e. at zero current, in an ignition coil with a magnetic circuit having just one permanent magnet set along the core.
  • the maximum variation of magnetic induction B allowed with respect to the point of rest is indicated in Figure 3 by ⁇ 2 and is greater than the variation of magnetic induction ⁇ 1 allowed without the presence of the permanent magnet.
  • Designated by the reference number 40 is the point of rest, i.e. at zero current, on the hypothesis of a magnetic circuit 2 with two permanent magnets 7 and 8, made, for example, of Sm-Co (samarium-cobalt) or Nd-Fe-B (neodymium-iron-boron) and set in parallel according to the embodiment of Figure 1.
  • Sm-Co sinarium-cobalt
  • Nd-Fe-B neodymium-iron-boron
  • Figure 3 moreover shows the qualitative evolution of a second characteristic curve 41, which represents the magnetic induction B as a function of the magnetizing force H of the magnetic circuit 2, the plates of which are preferably made of a ferromagnetic material with extremely high performance, such as for example iron and cobalt alloys.
  • the curve 41 is characterized by a slope, in the linear stretch, steeper than that of the curve 37 and above all is characterized by a linear stretch that is more extensive than that of the curve 37.
  • the use of high-performance materials for the provision of the plates in fact, entails raising of the saturation threshold in the characteristic curve B-H.
  • Designated by the reference number 43 is the point of rest on the hypothesis of a magnetic circuit 2 with two permanent magnets 7 and 8 with high power of magnetization set in parallel according to the embodiment of Figure 1.
  • the variation of magnetic induction allowed is indicated by ⁇ 5 and is decidedly higher than the variations ⁇ 3 and ⁇ 4 .
  • the present invention presents the advantages described in what follows.
  • the use of at least two permanent magnets, 7 and 8 or 26 and 27, set in parallel enables the dimensional limits imposed by the use of just one permanent magnet to be overcome.
  • an increase in the power of magnetization is obtained because the magnetic flux of the two branches in parallel of the magnetic circuit sum up, whilst the total reluctance of the magnetic circuit decreases because two reluctances in parallel are equivalent to one reluctance equal to one half. Consequently, the ignition coil 1 according to the present invention allows larger variations of magnetic induction B and hence enables high levels of reliability and of performance to be achieved.
  • the use of high-performance ferromagnetic materials such as, for example, the iron and silicon alloys or even more iron and cobalt alloys, for making the plates that form the magnetic circuit 2 enables even larger variations of magnetic induction, further improving the performance of the ignition coil 1.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Ignition Installations For Internal Combustion Engines (AREA)
EP06425582A 2006-08-09 2006-08-09 Bobine d'allumage Withdrawn EP1887589A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP06425582A EP1887589A1 (fr) 2006-08-09 2006-08-09 Bobine d'allumage

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP06425582A EP1887589A1 (fr) 2006-08-09 2006-08-09 Bobine d'allumage

Publications (1)

Publication Number Publication Date
EP1887589A1 true EP1887589A1 (fr) 2008-02-13

Family

ID=37596429

Family Applications (1)

Application Number Title Priority Date Filing Date
EP06425582A Withdrawn EP1887589A1 (fr) 2006-08-09 2006-08-09 Bobine d'allumage

Country Status (1)

Country Link
EP (1) EP1887589A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110197759A (zh) * 2018-02-26 2019-09-03 西门子公司 变压器、三相变压器及其接线方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3209294A (en) * 1962-10-23 1965-09-28 Westinghouse Electric Corp Magnetic core structures
DE2226289A1 (de) * 1971-05-11 1973-01-04 Tdk Electronics Co Ltd Vormagnetisierter magnetkern
US4480377A (en) * 1982-09-27 1984-11-06 General Motors Corporation Method of making an ignition coil core
US6211763B1 (en) * 1994-10-07 2001-04-03 Mitsubishi Denki Kabushiki Kaisha Ignition coil apparatus for an internal combustion engine and production method thereof
US20020171524A1 (en) * 2001-05-16 2002-11-21 Mu-Shui Tsai Ignition coil

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3209294A (en) * 1962-10-23 1965-09-28 Westinghouse Electric Corp Magnetic core structures
DE2226289A1 (de) * 1971-05-11 1973-01-04 Tdk Electronics Co Ltd Vormagnetisierter magnetkern
US4480377A (en) * 1982-09-27 1984-11-06 General Motors Corporation Method of making an ignition coil core
US6211763B1 (en) * 1994-10-07 2001-04-03 Mitsubishi Denki Kabushiki Kaisha Ignition coil apparatus for an internal combustion engine and production method thereof
US20020171524A1 (en) * 2001-05-16 2002-11-21 Mu-Shui Tsai Ignition coil

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110197759A (zh) * 2018-02-26 2019-09-03 西门子公司 变压器、三相变压器及其接线方法

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