JP2009038107A - Ignition coil for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil equipped with a relatively inexpensive center iron core exhibiting substitution property contributing to an increase in output and substitution for a grain-oriented silicon steel sheet. <P>SOLUTION: The ignition coil 1 includes: a secondary coil 220 composed of a secondary winding copper wire wound around a secondary core 3, a primary coil 210 composed of a primary winding copper wire wound around a primary core 4; the center iron core 6 that magnetic flux induced by the primary coil 210 penetrates; a cylinder portion 2 having the center iron core 6 at a center iron core insertion portion 310 forming the primary coil 210 or secondary coil 220; and an ignition plug fitting portion 800 for fitting an ignition plug formed at a distal end portion 301 of the cylinder portion 2. The center iron core 6 is constituted using a composite dust core soft magnetic material 600 contributing to substitution for the grain-oriented silicon steel sheet for the whole or part of the center iron core insertion part 310 of the secondary winding core 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ignition coil for an internal combustion engine for generating a spark from a spark plug.

  In an internal combustion engine such as an automobile, an ignition coil used to generate a spark from an ignition plug includes, for example, a secondary coil composed of a secondary winding copper wire wound around a secondary winding core, and a primary winding. A central coil that forms a primary coil composed of a primary winding copper wire wound around a core, a central iron core through which a magnetic flux induced by the primary coil passes, and a primary coil or a secondary coil A cylindrical portion having a central iron core at the insertion portion and a spark plug mounting portion for attaching a spark plug formed at the tip of the cylindrical portion.

  When the ignition timing signal from the electronic control unit of the internal combustion engine is sent to the switching element (igniter) connected in a circuit with the ignition coil, the ignition coil for the internal combustion engine is Predetermined power is supplied to the next coil and current flows. As a result, the primary coil generates a magnetic flux (lines of magnetic force) that passes in the axial direction of the central iron core. Then, when a certain current flows, the switching element (igniter) is operated by an ignition timing signal from the electronic control device to instantaneously cut off the current flowing through the primary coil. When this primary current is cut off suddenly, the magnetic flux (lines of magnetic force) disappears suddenly, so that the current flowing through the primary coil is the same as the current direction so that it does not disappear. An electromotive force is generated and an induced current flows. At the same time, an electromotive force due to electromagnetic mutual induction is generated by the magnetic flux (magnetic field lines) generated by the primary coil in the same manner for the secondary coil surrounding the central iron core and concentrically wound. An induced current flows and a high voltage is generated. And a spark can be generated from the spark plug attached to the spark plug attachment portion of the coil. At this time, the magnetic flux (line of magnetic force) generated by the primary coil is in an increasing contribution by passing through the central iron core.

  The iron core material used in the ignition coil has the same electromagnetic silicon steel sheet (electromagnetic silicon steel sheet) as that used in transformers such as power transmission / distribution electric power lines and transformers for a long time. Are non-oriented silicon steel sheets and directional silicon steel sheets). Especially in the case of a cylindrical ignition coil in which most or a part of the ignition coil body is accommodated in the ignition plug hole of an internal combustion engine for automobiles in recent years, the ignition plug hole must be accommodated in a small-diameter / small space portion. Therefore, it is necessary to make the configuration of a small, small-diameter, and lightweight ignition coil, and although it is a kind of transformer, it has a special transient phenomenon called an ignition coil as its operating principle, so it is necessary in that Greater performance output must be obtained, especially the core iron core material for the cylindrical ignition coil uses the most efficient magnetically oriented silicon steel sheet with the most excellent magnetic properties among electromagnetic silicon steel sheets. Has been. In recent years, with the increase in the output of automobile internal combustion engines, it has been desired to increase the output of cylindrical ignition coils.

  However, iron core materials used in transformers such as the above-mentioned power generation / substations and transmission / distribution power pole transformers are relatively inexpensive due to the large amount of use. Most of the silicon steel sheets are used. However, due to recent energy saving measures and global carbon dioxide gas reduction policies, this non-oriented silicon steel sheet has been converted to a relatively efficient directional silicon steel sheet with less loss (iron loss). Yes. In recent years, the global supply instability of steel products has accelerated, and it has become difficult to obtain stable materials as before. Further, unlike the non-oriented silicon steel sheet, the grain-oriented silicon steel sheet has a limited production capacity of the steel sheet itself, and is expected to be difficult to obtain.

  However, the ignition coil is based on a special transient phenomenon as described above, and can be used as a core iron core material that can replace the current directionally oriented silicon steel sheet that can output small and small diameter performance. Is not yet complete. As for higher power, the current direction-oriented silicon steel sheet is confronted with a peak. In short, there is a need for an optimal center iron core material that can suppress a significant increase in cost, can be replaced with a grain-oriented silicon steel sheet, and can contribute to performance improvement.

  The center iron core of a conventional cylindrical ignition coil has a predetermined surface made of an electromagnetic silicon steel sheet (non-directional, directivity) treated with an insulating coating with an inorganic or organic surface or a combination of both. Magnetic cores that were cut into widths and stacked in layers were used. Each individual steel sheet cut to a predetermined width is provided with a protruding portion and a recessed portion and fixed by caulking to form a single magnetic core.

Patent Document 1 discloses a cylindrical ignition coil that uses a dust material (permendur etc.) as a central iron core.
JP 2006-278499 A

  The present invention has been solved in view of such conventional problems, can be replaced with a grain-oriented silicon steel sheet, and can contribute to improvement in performance due to high output, thereby suppressing and substantially increasing the cost. It is an object of the present invention to provide an ignition coil for an internal combustion engine provided with a central iron core material.

  In the center iron core that has been cut and fixed by caulking, the cylindrical ignition coil that is housed in the ignition plug hole of an internal combustion engine for automobiles in recent years is housed in a small-diameter / small space portion called an ignition plug hole. Therefore, it is necessary to select a material that constitutes the ignition coil, which is small diameter, small size, light weight, and in which the required performance output can be obtained, and special transient phenomenon called ignition coil In order to make the principle of operation, a magnetic iron core material that can cope with the special transient phenomenon is desired. Furthermore, in recent years, related ignition systems using high frequency for the ignition system have been developed, and improvement of magnetic characteristics in a high frequency band is required for ignition coils corresponding to them.

  However, as the central iron core in the magnetic material as described above, there is still no alternative magnetic material that can handle the same or higher electrical characteristics and transients in the former. In the latter high-frequency band, the conventional electromagnetic silicon steel sheet can not be optimally effective only in a frequency band at a relatively low frequency, which is inappropriate. In addition, the conventional iron cores with ordinary powdered materials (permendur, etc.) that have been developed so far have not been able to perform as an ignition coil at all, and especially in the low magnetic field region (primary) unique to dust compaction. There was a fact that the performance characteristics as an ignition coil in a current range of 4A to 13A (breaking current) could not be obtained.

  In order to solve this problem, an insulating film is applied to a powder of soft magnetic material containing pure iron as a main component, one of each powder (70 μm to 120 μm), and after applying the insulating film, bonding An agent and the like are mixed, the powder is filled in a mold in which this powder is formed in advance, and high-density pressure molding is performed at a high pressure. Furthermore, it is carried out by a method of forming a molded product by performing a heat treatment at 340 ° C. to 550 ° C. in terms of removing distortion during pressure molding or semi-firing.

  According to the composite dust soft magnetic material of the present application, an improvement having magnetic characteristics can be obtained in order to overcome the above problems. In addition, there is an advantage that magnetic properties in a high frequency band and a high current magnetic field, which cannot be achieved with a silicon steel plate, can be improved, and an improvement can be obtained.

  The present invention includes a secondary coil composed of a secondary winding copper wire wound around a secondary winding core, a primary coil composed of a primary winding copper wire wound around the primary winding core, A cylindrical portion having a central iron core through which a magnetic flux induced by the primary coil passes, and a central iron core at a central iron core insertion portion forming the primary coil or the secondary coil, and formed at the tip of the cylindrical portion In the ignition coil having a spark plug mounting portion for mounting the spark plug, the central iron core is replaced with a directional silicon steel sheet inserted into the central core insertion portion of the secondary winding core. An ignition coil for an internal combustion engine, characterized in that it is made of a composite powder soft magnetic material that can contribute (claim 1).

  The composite dust soft magnetic material preferably has a constituent density of 7.0 g / cm 3 or more. In this case, a sufficient magnetic flux density can be obtained in the composite dust soft magnetic material. When the constituent density is less than 7.0 g / cm 3, there is a possibility that a sufficient magnetic flux density cannot be obtained in the composite dust soft magnetic material. Therefore, there is a possibility that the effect of increasing the magnetic flux passing through the central iron core, which can be achieved with the composite dust soft magnetic material, may not be sufficiently obtained.

  Moreover, it is preferable that the said composite powder soft magnetic material is 70 W / Kg or less when an iron loss is W10 / 400 (Claim 3). In this case, in the composite dust soft magnetic material, sufficient output performance characteristics can be obtained during operation of the ignition coil. If the iron loss is greater than 70 W / Kg at W10 / 400, the maximum output performance characteristic required for the ignition coil may not be sufficiently obtained.

  The composite dust soft magnetic material preferably has a saturation magnetic flux density of 1.50 T or more. In this case, a sufficient magnetic flux density can be obtained in the composite dust soft magnetic material. When the saturation magnetic flux density is less than 1.50 T, there is a possibility that a sufficient magnetic flux density cannot be obtained in the composite dust soft magnetic material. Therefore, there is a possibility that the effect of increasing the magnetic flux passing through the central iron core cannot be obtained sufficiently.

  Further, the composite dust soft magnetic material used as the central iron core is divided into a plurality of block layers in the radial direction of the entire central iron core, and the composite dust soft magnetic material and the electromagnetic ceramic are divided into at least one block. The base steel plate blocks can be arranged alternately and configured. In either case, the magnetic flux passing through the central iron core can be effectively and efficiently increased.

  Further, both ends in the axial direction of the central iron core formed by the composite dust soft magnetic material, or the composite dust soft magnetic material, and a block for each of a plurality of axes of the electromagnetic silicon steel sheet, which is the central iron core, Alternatively, a permanent magnet can be arranged at least at one end (claim 6). In this case, the magnetic flux passing through the central iron core can be further increased.

  In the composite dust soft magnetic material used as the central iron core, each individual particle is coated with an insulating coating, and the thickness of the insulating coating is preferably 7 to 120 nm. ). In this case, there is an effect of suppressing eddy current loss generated by the magnetic flux passing through the central iron core, and if it is outside the above film thickness range, first, if it is thin, insulation between individual particles is performed. There is a risk that it cannot be secured. On the other hand, if it is thick, the proportion of the magnetic material itself decreases with the increase in thickness of the central iron core, and the magnetic properties are deteriorated.

  In the composite dust soft magnetic material used as the central iron core, the particle diameter of each individual particle is preferably 70 to 120 μm. In this case, a sufficient magnetic flux density can be obtained in the composite dust soft magnetic material. If it is outside the particle size range, first, if it is a small case, the amount of each individual particle increases as a whole with respect to the entire central iron core, and the proportion of the particle film that is an insulating film increases. As a result, the ratio of the magnetic material itself decreases, and the magnetic properties are deteriorated. On the other hand, if the particles are large, eddy current loss increases in the individual particles, and the magnetic properties deteriorate.

  Further, the composite dust soft magnetic material used as the central iron core is made of any one of fluorine, silicone, epoxy, and the like on the outer surface of the composite dust soft magnetic material. A thin film separating member can be applied to form a structure. In this case, the outer surface of the composite dust soft magnetic material, which is the central iron core, and the epoxy resin and the secondary core surrounding the outer surface of the composite dust soft magnetic material are separately provided. It can be separated to expand and contract. Therefore, since it prevents the occurrence of cracks in the composite dust soft magnetic material and the epoxy resin in contact with the composite dust soft magnetic material, it prevents the occurrence of creeping leakage (discharge) along the cracks. it can.

  Further, the composite dust soft magnetic material used as the central iron core is a base material made of either one of polyethylene terephthalate or polyphenylene sulfide on the outer surface of the composite dust soft magnetic material, A film-like sheet and a thin film separating member such as a tape may be interposed therebetween (claim 8). In this case, the outer surface of the composite dust soft magnetic material, which is the central iron core, and the epoxy resin and the secondary core surrounding the outer surface of the composite dust soft magnetic material are separately provided. It can be separated to expand and contract. Therefore, it prevents the occurrence of cracks in the composite dust soft magnetic material and the epoxy resin in contact with the composite dust soft magnetic material, and thus prevents the occurrence of creeping leakage (discharge) along the cracks. it can.

  Moreover, the composite powder soft magnetic material used as the central iron core can be configured by combining at least two. Accordingly, it is possible to provide an ignition coil for an internal combustion engine including a central iron core that is inexpensive, can be replaced, and also exhibits improved performance.

  As described above, according to the present invention, it can contribute to the grain-oriented silicon steel plate as an alternative. And with a central iron core that contributes to the improvement of performance that could not be achieved at all with the compact material that has been developed conventionally (for example, permendur), is inexpensive, can be replaced, and also exhibits improved performance, An ignition coil for an internal combustion engine can be provided.

  (Embodiment 1) An internal combustion engine ignition coil (hereinafter referred to as "ignition coil") according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the ignition coil 1 of the present embodiment is wound around a secondary coil 220 composed of a secondary winding copper wire wound around the secondary winding core 3 and the primary winding core 4. A primary coil 210 made of a primary winding copper wire, a central iron core 6 through which a magnetic flux induced by the primary coil 210 passes, and a central iron core insertion forming the primary coil 210 or the secondary coil 220 The part 310 includes a cylindrical part 2 provided with the central iron core 6 and a plug attachment part 800 formed on the tip part 301 of the cylindrical part 2 for attaching an ignition plug. The central iron core 6 is configured by using the composite dust soft magnetic material 600 shown in FIG. 2 which can contribute to the directional silicon steel plate as a whole or a part of the central iron core insertion portion 310 of the secondary winding core 3. It is. This will be described in detail below.

  The cylindrical portion 2 is formed by disposing an outer iron core 230, a primary coil 210, a secondary coil 220, and a central iron core 6 in a coil outer case 201 made of synthetic resin. The primary coil 210 is formed by winding a copper wire that has been subjected to an insulating coating treatment on the outer peripheral surface of a primary winding core 4 made of a synthetic resin formed in a cylindrical shape. Similarly, the secondary coil 220 is formed by winding a copper wire having an insulating coating on the outer peripheral surface of the secondary winding core 3 made of a synthetic resin similarly formed in a cylindrical shape.

  Further, the primary coil 210 is inserted inside an outer iron core 230 made of a cylindrical metal magnetic material (for example, an electromagnetic silicon steel plate), and the outer iron core 230 is inserted into the coil outer case 201. It is arranged. The secondary coil 220 is inserted and arranged on the inner peripheral side of the primary coil 210, and the central iron core 6 made of the composite dust soft magnetic material 600 is inserted and arranged on the inner peripheral side of the secondary coil 220. Has been. Moreover, the permanent magnet 240 is arrange | positioned in the axial direction both ends of the center iron core 6 in the direction which can generate | occur | produce the magnetic flux of the direction opposite to the direction of the magnetic flux which the primary coil 210 generate | occur | produces. Also, between the outer case 201 and the outer iron core 230, between the outer iron core 230 and the primary coil 210, between the primary coil 210 and the secondary coil 220, the secondary coil 220 and the composite dust soft magnetic material. Insulating resin 250 is filled in each gap between the central iron core 6 and 600 and other gaps. In this embodiment, an epoxy resin is used as the insulating resin 250.

  Next, the center iron core 6 made of the composite dust soft magnetic material 600 will be described in detail with reference to FIG. The central iron core 6 is coated with an insulating film having a heat resistance of 7 to 120 nm on the surface of the individual iron powder of a soft magnetic material such as pure iron powder. In this case, the individual iron powder after the insulating film is coated. The average particle size is about 70 to 120 μm. In addition, the insulating coatings of individual iron powders are well-definition, and can be easily bonded and bonded. Adhesive binders, etc. are coated or mixed separately, and the molds are filled with a predetermined amount, and then compression molded. Then, after solidifying, it can be created by further curing the adhesive (binder) and heat treatment (340 ° C. to 550 ° C.) for removing the distortion that occurs when compression molding is performed.

  Also, in this example, each iron powder soft magnetic material with an insulating coating was prepared by compression molding, solidifying, and heat treatment together with an adhesive (binder). 7.1 g / cm 3 was used.

  Also, in this example, the iron loss of each iron powder soft magnetic material with an insulating coating formed by compression molding together with an adhesive (binder), solidification, and heat treatment is W10 / At 400, 69 W / Kg was used.

  Moreover, in this example, the soft magnetic material of each iron powder with an insulating coating was compression-molded together with an adhesive (binder), solidified, and heat-treated. The saturation magnetic flux density was 1 .55T was used.

  A plug mounting portion 800 for mounting a spark plug is positioned at the tip portion 301 of the cylindrical portion 2. In the plug attachment portion 800, a compression spring 710 is disposed on the ignition coil side that is connected to the ignition plug on the internal combustion engine side. The compression spring 710 is electrically connected to the secondary high voltage side terminal portion of the secondary coil 220 via the secondary high voltage terminal 720.

  The switching element circuit 400 is positioned in the switching element circuit storage portion 900 of the ignition coil body 1, and the switching element circuit 400 is wired to distribute power to the primary coil 210. Further, the switching element circuit 400 is provided with a power distribution to the primary coil 210 and a signal from an on-vehicle electronic control device so that the power can be shut off in a defensive manner. Further, the switching circuit housing portion 900 is filled and solidified with an insulating resin 250.

  In the ignition coil 1, when the ignition timing signal from the on-vehicle electronic control device is distributed to the switching element circuit, the built-in switching element and the like operate defensively, and the primary coil 210 receives power. When the electric current is transmitted and a certain current flows, the switching element is operated, and the current flowing through the primary coil is instantaneously cut off. Therefore, if the primary current is suddenly interrupted, the magnetic flux (lines of magnetic force) disappears suddenly, so that the current that has flowed through the primary coil does not disappear in the primary current direction as before. An electromotive force is generated so that an induced current flows. As a result, the primary coil 210 generates a magnetic flux (line of magnetic force) that passes through the magnetic circuit, and this magnetic flux (line of magnetic force) surrounds the central iron core and is also wound around the secondary coil wound concentrically. Similarly, an electromotive force is generated by electromagnetic mutual induction, an induced current flows, and a high voltage is generated. And a spark can be generated from the spark plug attached to the spark plug attachment portion of the coil.

  The effect in the ignition coil 1 of this example is demonstrated. In the ignition coil 1 of the present example, the central iron core 6 is a composite powder soft magnetic material 600 that can be replaced with a directional silicon steel plate in the whole or a part of the central iron core insertion portion 310 of the secondary winding core 3. It is made using. Here, the ignition coil 1 generates a magnetic flux (lines of magnetic force) that passes through the central iron core 6 by supplying electric power to the primary coil 210. At this time, the magnetic properties such as the magnetic flux density in the central iron core 6 can be the same as or better than those of the grain-oriented silicon steel plate.

  Therefore, like the ignition coil 1 of this example, magnetic properties such as magnetic flux density when magnetic flux (magnetic field lines) is generated can be equivalent to or better than directional silicon steel plates. By using the magnetic member as an inferior magnetic member, the magnetic flux passing through the central iron core 6 can be efficiently and effectively exhibited. As a result, it is possible to generate an induced electromotive force generated in the secondary coil 220 by being induced by a magnetic flux (line of magnetic force) that can be generated, and at the same time, it is possible to generate a spark from the spark plug.

  Moreover, in this example, the central iron core 6 uses a compacting material having a constituent density of 7.1 g / cm 3, and a high magnetic permeability capable of obtaining efficient and effective output performance can be obtained. .

  Further, in this example, the center iron core 6 uses a powder material of 69 W / Kg when the iron loss is W10 / 400, and can suppress eddy current loss and hysteresis loss as much as possible, thereby efficiently. Effective output performance can be obtained.

  Further, in this example, the central iron core 6 is made of a powdered material having a saturation magnetic flux density of 1.55 (T), so that a more appropriate magnetic flux density can be obtained and efficient and effective output performance can be obtained. Can be obtained.

  In addition, permanent magnets 240 are disposed at both axial ends of the central iron core 6. The permanent magnet 240 is disposed so that the primary coil 210 generates a magnetic flux (lines of magnetic force) in a direction opposite to the magnetic flux (lines of magnetic force) that can be induced. Therefore, a reverse bias can be applied by the magnetic flux (lines of magnetic force) that can be generated by the permanent magnet 240. By applying this reverse bias, the induced electromotive force generated in the secondary coil 220 can be further increased as compared with the case where no permanent magnet is arranged. In this case, the permanent magnet 240 may not be disposed.

  (Embodiment 2) It can also be carried out as follows. As shown in FIG. 3, this example is an example in which, in the central iron core 6 of Example 1, a composite dust soft magnetic material, an electromagnetic silicon steel plate, and a block are provided. As shown in FIG. 3, the radial direction of the central iron core 6 is divided into a plurality of portions, and the first composite dust soft magnetic material 622 is sandwiched between the conventional directional silicon steel plate 611 in the center. The second composite dust soft magnetic material 623 is alternately arranged. At this time, a plurality of sections may be configured as at least one block. By comprising in this way, the magnetic flux which passes the said center iron core 6 can be increased effectively and efficiently, and magnetic characteristics, such as a magnetic flux density in the center iron core 6, are equivalent to a directional silicon steel plate. Or more magnetic properties can be obtained. The rest of the configuration is the same as that of the first embodiment, and provides functional effects.

  Moreover, in addition to the structure of the said Example 1 and Example 2, as shown in FIG. 4, as shown in FIG. A thin film separating member may be interposed. In this case, the outer surface of the central iron core and the epoxy resin and the secondary core surrounding the outer surface of the central iron core can be separated so as to be able to expand and contract separately. Accordingly, since the occurrence of cracks in the composite dust soft magnetic material and the epoxy resin in contact with the composite dust soft magnetic material is protected, it is possible to protect the occurrence of creeping leakage (discharge) along the cracks. The thin film separating member is made of any material such as fluorine, silicone, or epoxy, and the thin film separating member is either polyethylene terephthalate or polyphenylene sulfide. A film-like sheet, a tape or the like, which is a base material made of, is applied.

  As mentioned above, although the Example of this invention was shown, in the structure, combination, and material of a center iron core, in the range which does not deviate from the meaning of this invention, it can change suitably and it replaces with the conventional grain-oriented silicon steel plate, and can be substituted. It is possible to provide an ignition coil for an internal combustion engine that includes a central iron core that exhibits a relatively inexpensive and excellent performance.

The longitudinal cross-sectional view which shows the structure of the ignition coil in Example 1 of this invention. The front view and top view which comprised the center iron core of FIG. 1 using the composite dust soft magnetic material. The front view and top view which show the structure which uses the composite powder soft magnetic material for the block layer for every axis | shaft in the center iron core in Example 2 of this invention. Sectional drawing which shows the structure which apply | coated the separation member to the center iron core surface of this invention. Sectional drawing which shows the structure which carried out the interposition process of the separation member on the center iron core surface of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ignition coil 2 Cylindrical part 3 Secondary winding core 4 Primary winding core 6 Central iron core 201 Coil outer case 210 Primary coil 220 Secondary coil 230 Outer iron core 240 Permanent magnet 250 Insulating resin 301 Tip part 310 Center iron core insertion Portion 400 Switching element circuit 600 Composite dust soft magnetic material 611 Oriented silicon steel plate 622 First composite dust soft magnetic material 623 Second composite dust soft magnetic material 650, 660 Separation member 710 Compression spring 720 Secondary high voltage terminal 800 Spark plug mounting part 900 Switching element circuit storage part

Claims (11)

  A secondary coil composed of a secondary winding copper wire wound around a secondary winding core, a primary coil composed of a primary winding copper wire wound around a primary winding core, and the primary coil A cylindrical portion provided with a central iron core through which the magnetic flux induced in step 1 passes and a central iron core insertion portion forming a primary coil or a secondary coil, and a spark plug formed at the tip of the cylinder are attached. In the ignition coil for an internal combustion engine having a spark plug mounting portion for the purpose, the central iron core can contribute to the directional silicon steel sheet formed by being inserted into the central iron core insertion portion of the secondary winding core. An ignition coil for an internal combustion engine, characterized by comprising a composite powder soft magnetic material.   2. The ignition coil for an internal combustion engine according to claim 1, wherein the composite powder soft magnetic material has a constituent density of 7.0 g / cm <3> or more.   2. The ignition coil for an internal combustion engine according to claim 1, wherein the composite powder soft magnetic material has an iron loss of 70 W / Kg or less when W10 / 400.   2. The ignition coil for an internal combustion engine according to claim 1, wherein the composite dust soft magnetic material has a saturation magnetic flux density of 1.50 (T) or more.   The composite dust soft magnetic material according to claim 1, wherein the composite dust soft magnetic material is divided into block layers for each of a plurality of axes in a radial direction of the entire central iron core, and is made of the composite dust soft magnetic material in at least one block. An ignition coil for an internal combustion engine.   2. The ignition coil for an internal combustion engine according to claim 1, wherein permanent magnets are disposed at both ends or at least one end of the central iron core in the axial direction.   2. The composite dust soft magnetic material according to claim 1, wherein each individual particle is coated with an insulating coating to suppress eddy current loss, and the thickness of the insulating coating is 7 to 120 nm. An ignition coil for an internal combustion engine, which is characterized.   2. The ignition coil for an internal combustion engine according to claim 1, wherein the composite dust soft magnetic material has an average particle diameter of 70 to 120 [mu] m.   The thin film separating member made of any one material of fluorine-based, silicone-based, or epoxy-based coating material is applied to the outer surface of the composite dust soft magnetic material according to claim 1. An ignition coil for an internal combustion engine.   2. The base material according to claim 1, wherein the outer surface of the composite dust soft magnetic material includes a base material made of any one of polyethylene terephthalate, polyphenylene sulfide, and the like on the outer surface of the composite dust soft magnetic material. An internal combustion engine ignition coil characterized by interposing a film-like sheet and a thin film separating member such as a tape.   11. An ignition coil for an internal combustion engine according to claim 1, wherein at least two or more are combined.