JP2007103482A - Ignition coil for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil of a closed magnetic circuit equipped with a magnet which is improved in assembling height, and has a high reliability by presenting the structure of the magnet and iron core optimal for the performance of the ignition coil. <P>SOLUTION: A center-side iron core 51 includes a nearly T-shaped portion 57a in one end which becomes a joint surface with an outer peripheral side iron core 54. Compared with the other end of the center-side iron core 51, the cross section in the magnetic path direction of the nearly T-shaped portion 57a is gradually widened. The magnet 81 has a joint area smaller than the area of the nearly T-shaped portion of the center-side iron core where the magnet is to be attached. The nearly T-shaped portion has a concave portion for partially holding the magnet. The magnet is attached to the ignition coil in such a manner that part of the magnet in the thickness direction may be embedded in the concave portion, with the remaining part in the thickness direction sticking out of the concave portion. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ignition coil device for an internal combustion engine, and more particularly to a structure of an iron core and a magnet.

  Engines used in recent automobile internal combustion engines have conflicting demands for high output with lean combustion in consideration of the global environment, and the demand for ignition coils for internal combustion engines that generate high energy corresponding to that demand has increased. ing. In addition, there is a demand for miniaturization of the ignition coil, and in order to maintain the performance of the ignition coil while corresponding to the reduction in the diameter, it is essential to increase the efficiency of the magnetic circuit. 4A is a top view of the conventional internal combustion engine ignition coil before filling with an insulating material, FIG. 4B is a longitudinal sectional view taken along line AA of FIG. 5A, and FIG. The longitudinal cross-sectional view of the combination of the iron core and magnet which comprise the ignition coil for internal combustion engines of this is shown.

  4 to 5, the ignition coil 1 to which the prior art is applied includes a primary coil 23 wound with a primary copper wire and a secondary coil 14 wound with a secondary copper wire on the outer periphery thereof. These primary coil 23 and secondary coil 14 are housed in a case 30. The primary copper wire end of the primary coil 23 is electrically connected to a primary connector terminal 41 provided in a primary connector 40 attached to the primary bobbin 21, and one end of the secondary coil 14 is connected. The high voltage side is connected to the secondary bobbin terminal B13, and the secondary bobbin terminal B13 is electrically connected to the secondary high voltage terminal 15. The low voltage side end of the other secondary coil 14 is connected to the secondary bobbin terminal A12 and electrically connected to the primary connector terminal 41. Further, the primary coil 23 and the secondary coil 14 provided with the primary connector 40 are embedded in the case 30 and are integrally molded by injecting and curing an epoxy resin 70. Further, an I-type central iron core 53 is inserted into the internal space of the primary bobbin 21, and an O-type outer peripheral iron core 56 that forms a closed magnetic circuit with the central iron core 53 is located outside the coil. Is located. The center side iron core 53 and the outer periphery side iron core 56 have a quadrangular or cylindrical cross section in the magnetic path direction, and have an iron core shape having substantially the same cross-sectional area from one end to the other end. Further, both or one of the joint surfaces of the center side iron core 53 and the outer peripheral side iron core 56 are flat surfaces, and the reverse of the magnetic field generated in the primary coil 23 having the same area as the joint surface and a flat surface. A magnet 83 for applying a bias is mounted without a gap. For this reason, the shortest space gap h <b> 3 between the central iron core 53 and the outer iron core 56 is the thickness of the magnet 83.

  The conventional ignition coil is an ignition coil that supplies a high voltage to the ignition plug, and the low voltage side of the secondary coil 14 is electrically connected to the primary coil 23. When an ignition signal is input to the base side (B) of 60, a current flows into the primary coil 23 from + of the battery power source 51 (not shown) to generate a magnetic field, and the generated magnetic field is held in the iron core 60. Next, when the ignition signal on the base side (B) of the switching element 60 is cut off, the current flowing in the primary coil 23 is also cut off, and the high ratio according to the turn ratio of the primary coil 23 and the secondary coil 14 is high. The voltage is excited by the secondary coil 14 and distributed to a spark plug 80 (not shown) that is electrically connected to the secondary coil 14. Further, the magnet of the prior art has a thickness of 0.7 mm to 0.9 mm, and there is little loss as a magnetic resistance, so that the rise of the primary current is quick, and the secondary output energy can be secured.

  However, in the above configuration, when the ignition coil is assembled, the plate thickness is 0.7 mm to 0.9 mm, so it is easy to break and the assembling stand remains. Moreover, since it is easy to break, there was a loss of magnet material, and it was wasted if it broke. In addition, the conventional thin magnets have a problem in heat resistance because the permeance coefficient is lowered.

  In order to improve this, a thick magnet is mounted. However, if the magnet is thick, the shortest space gap h between the center side iron core and the outer side iron core is widened. Since the start-up is delayed and the required secondary output energy cannot be secured, the current value performance of the ignition coil is lowered and the output performance of the ignition coil is lowered. Therefore, the present invention solves the above-mentioned problems, and provides an ignition coil having a magnet and an iron core structure that is optimal for ignition coil performance and having good reliability for an ignition coil of a closed magnetic circuit magnetic circuit equipped with a magnet. Objective.

  In order to solve the above-described problems, in the present invention, in claim 1, the primary coil wound with the primary copper wire, the secondary coil wound with the secondary copper wire, and the inner space of the primary bobbin are inserted. A reverse bias of a magnetic field generated in the primary coil on a joint surface between the central iron core, the outer iron core forming a closed magnetic circuit with the central iron core, and the central iron core and the outer iron core. In the ignition coil including the magnet to be applied, the center side iron core is widened such that one end of the center side iron core, which is a joint surface with the outer periphery side iron core, gradually increases in cross section in the magnetic path direction from the other end. The center side iron core and the outer peripheral side iron core are made of non-oriented silicon steel plates, and the magnet is the substantially T shape of the center side iron core to which the magnet is mounted. A magnet having a bonding area smaller than an area of the shape portion, wherein the substantially T-shaped portion is a part of the magnet; An ignition coil for an internal combustion engine having a recess to hold, wherein the magnet is mounted in a state where a part of the magnet in the thickness direction is embedded in the recess and a part of the magnet in the thickness direction protrudes To do. The ignition coil for an internal combustion engine according to claim 1, wherein a material used for the magnet is an Sm-Co-based or Nd-Fe-B-based rare earth magnet.

  With the configuration described above, even when a thick magnet is mounted, the shortest spatial gap h of a part of the magnetic path can be narrowed, and a closed magnetic circuit having a smaller magnetic resistance can be formed accordingly. Therefore, the rise of the primary current can be accelerated and the required secondary output energy can be secured.

  As described above, according to the present invention, the ignition coil of the closed magnetic circuit magnetic circuit equipped with the magnet can be provided with an optimum magnet and iron core structure for the ignition coil performance and excellent reliability.

  FIG. 1 shows a longitudinal sectional view of a combination of an iron core and a magnet constituting an embodiment 1 of an ignition coil for an internal combustion engine according to the present invention, and FIG. 2 shows an embodiment 2 of the ignition coil for an internal combustion engine according to the present invention. FIG. 3 shows a longitudinal sectional view of a combination of an iron core and a magnet constituting the iron core, and FIG. 3 shows an ignition coil for an internal combustion engine having an iron core made of a non-oriented silicon steel plate according to the first embodiment of the present invention and the prior art. The figure which showed the comparison with magnetization force nI [AT] of this and magnetic flux (phi) [wb] is shown.

  The ignition coil of the present invention shows only the difference from the prior art. In FIG. 1, an I-type center-side iron core 51 of the ignition coil for an internal combustion engine according to the first embodiment of the present invention has one end of a center-side iron core 51 that serves as a joint surface with an O-type outer-side iron core 54. It has a substantially T-shaped portion 57a that spreads out from the other end and has a gradually increasing cross section in the magnetic path direction. The magnet 81 is a magnet 81 having a bonding area smaller than the area of the substantially T-shaped portion 57 a of the central iron core 51 to which the magnet 81 is mounted. The substantially T-shaped portion 57 a is the magnet 81. A recess 58a having a constant depth and holding a part of the recess 58a. Therefore, the magnet 81 is mounted and held in a state where a part in the thickness direction is embedded in the recess 58a and a part in the thickness direction of the magnet 81 protrudes. Therefore, the shortest space gap h1 between the central iron core 51 and the outer iron core 54 is inevitably provided.

  In addition, as shown in FIG. 3, when the magnet thickness is shared by 1 mm and the shortest spatial gap h is 1 mm and 0.8 mm, the magnetizing force nI of the iron core internal combustion engine ignition coil made of a non-oriented silicon steel plate is used. The relationship between [AT] and magnetic flux φ [wb] was compared. As a result, since the shortest spatial gap h between the center side iron core and the outer side iron core has a narrow portion, the magnetic resistance is partially reduced and the rise of the primary current can be accelerated. Moreover, since a relatively thick magnet that is difficult to break can be used, there is no loss of magnet material, the assemblability can be improved, the permeance coefficient does not decrease, and heat resistance does not have to be a problem.

  In particular, it has been found that the center-side iron core and the outer-side iron core are made of non-oriented silicon steel plates, which are more effective than any other type of silicon steel plates.

  In FIG. 2, the I-type central iron core 52 of the ignition coil for an internal combustion engine according to the second embodiment of the present invention is a central iron core 52 that serves as a joint surface with a U-shaped outer peripheral iron core 55. One end of each has a substantially T-shaped portion 57b that is divergent from the other end and has a gradually increasing cross section in the magnetic path direction. The magnet 82 is a magnet 82 having a bonding area smaller than the area of the substantially T-shaped portion 57b of the central iron core 52 to which the magnet 82 is mounted. The substantially T-shaped portion 57b is the magnet 82. A recess 58b having a constant depth and holding a part of the recess 58b. Therefore, the magnet 82 is mounted and held in a state where a part in the thickness direction is embedded in the recess 58b and a part in the thickness direction of the magnet 82 protrudes. Therefore, the shortest space gap h2 between the central iron core 52 and the outer peripheral iron core 55 is inevitably provided. Since the shortest spatial gap h between the center side iron core and the outer peripheral side iron core has a narrow portion as in the first embodiment, a part of the magnetic resistance is reduced and the rise of the primary current can be accelerated. Moreover, since a relatively thick magnet that is difficult to break can be used, there is no loss of magnet material, the assemblability can be improved, the permeance coefficient does not decrease, and heat resistance does not have to be a problem. With the configuration as described above, it is possible to provide an ignition coil having a magnet and iron core structure that is optimal for ignition coil performance and having good reliability.

  In the above-described embodiment, the size of the magnet is a magnet having a bonding area smaller than the area of the substantially T-shaped portion of the central iron core on which the magnet is mounted. Especially if it is smaller than the area and has the action of applying a reverse bias of the magnetic field generated in the primary coil, satisfying the required ignition performance and exhibiting an effect equivalent to the above-mentioned effect, in particular There is no limitation on the size, position in the recess, and material. Moreover, in the said Example, although the said recessed part had fixed and the same depth, if the said magnet can be hold | maintained, depth will not be limited to a fixed and the same. For example, a recess having a smaller mouth area than the magnet may be provided on the bottom of the recess. That is, various modifications can be made without departing from the spirit of the present invention. In addition, the above embodiment has been specifically described, but the specific description content does not particularly limit the present invention. Similarly, various modifications can be made without departing from the spirit of the present invention.

It is a longitudinal cross-sectional view of the combination of the iron core and magnet which comprise Example 1 of the ignition coil for internal combustion engines of the technique of this invention. The longitudinal cross-sectional view of the combination of the iron core and magnet which comprises Example 1 of the ignition coil for internal combustion engines of the technique of this invention is shown. A comparison between the magnetizing force nI [AT] and the magnetic flux φ [wb] of the ignition coil for an iron-core internal combustion engine composed of a non-oriented silicon steel plate between Example 1 of the technology of the present invention and the conventional technology is shown. FIG. (A) is a top view before the insulating material filling of the conventional internal combustion engine ignition coil, (b) is the longitudinal cross-sectional view cut off by AA of (a). It is a longitudinal cross-sectional view of the combination of the iron core and magnet which comprise the ignition coil for internal combustion engines of a prior art.

Explanation of symbols

1 Ignition coil 11 Secondary bobbin 12 Secondary bobbin terminal A
13 Secondary bobbin terminal B
14 Secondary coil 15 Secondary high voltage terminal 21 Primary bobbin 22 Primary bobbin terminal 23 Primary coil 30 Case 40 Primary connector 41 Primary connector terminal 50 Iron core 51, 52, 53 Center side iron core 54, 55, 56 Outer peripheral side iron cores 57a, 57b Substantially T-shaped portions 58a, 58b Recess 60 Switching element 70 Epoxy resin 81, 82, 83 Magnet

Claims (5)

  A primary coil wound with a primary copper wire, a secondary coil wound with a secondary copper wire, a central iron core inserted into the internal space of the primary bobbin, the central iron core and a closed magnetic circuit An ignition coil comprising: an outer peripheral side iron core that forms a core; and a magnet that applies a reverse bias of a magnetic field generated in a primary coil to a joint surface between the central side iron core and the outer peripheral side iron core. Has a substantially T-shaped portion with one end of the center-side iron core that becomes a joint surface with the outer peripheral-side iron core having a substantially T-shaped portion that widens toward the end in a magnetic path direction from the other end. Has a recess for holding a part of the magnet, and the magnet is mounted in a state where a part in the thickness direction is embedded in the recess and a part in the thickness direction of the magnet protrudes. An ignition coil for an internal combustion engine.   The magnet is a magnet having a bonding area smaller than a bonding area between the central iron core and the outer iron core of the substantially T-shaped portion of the central iron core on which the magnet is mounted. The ignition coil for an internal combustion engine according to claim 1.   A primary coil wound with a primary copper wire, a secondary coil wound with a secondary copper wire, a central iron core inserted into the internal space of the primary bobbin, the central iron core and a closed magnetic circuit An ignition coil comprising: an outer peripheral side iron core that forms a core; and a magnet that applies a reverse bias of a magnetic field generated in a primary coil to a joint surface between the central side iron core and the outer peripheral side iron core. The one end of the center side iron core that becomes the joint surface with the outer periphery side iron core has a substantially T-shaped portion that is divergent in which the cross section in the magnetic path direction is gradually larger than the other end, and the outer periphery side iron core is And a concave portion for holding a part of the magnet at a joint surface between the center side iron core and the outer peripheral side iron core, and the magnet is partially embedded in the thickness direction in the concave portion to obtain a thickness of the magnet. An ignition coil for an internal combustion engine, which is mounted in a state where a part of the vertical direction protrudes.   The ignition coil for an internal combustion engine according to claim 3, wherein the magnet is a magnet having a joint area smaller than a joint area between the outer peripheral iron core and the central iron core on which the magnet is mounted.   5. The ignition coil for an internal combustion engine according to claim 1, wherein a material used for the magnet is an Sm—Co or Nd—Fe—B rare earth magnet.

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