JPH04102306A - Ignition coil for internal combustion engine - Google Patents

Abstract

PURPOSE:To suppress the leakage of magnetic flux and increase output voltage without causing an ignition coil to be increased, by housing an internal coil comprising a plurality of core members inside a primary coil and installing permanent magnets between the adjacent core members respectively. CONSTITUTION:A primary current is supplied to a primary coil 21 of ignition coil 1 and, if said current is intermittently applied at a predetermined frequency, then a change in magnetic flux occurs at an internal core 10 and external cores 14 and 15 including permanent magnets 18 and 19. Then, a predetermined high voltage occurs at a secondary coil 22, and this high voltage is supplied to an ignition plug directly from a secondary connector 32 or through a distributor. In this case, a large change in effective magnetic flux can be ensured by means of the magnets 18 and 19 interposed between core members 11, 12 and 13 of a core 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition coil for an internal combustion engine, and more particularly to an ignition coil that increases output voltage by interposing a permanent magnet in a magnetic path.

[Prior art] An ignition system for an internal combustion engine: - Intermittently supplies a secondary current to an ignition coil, and supplies a high voltage generated on the next side according to changes in magnetic flux in the coil to the ignition plug, thereby increasing the mixture in the cylinder. It's something that ignites your mind.

Regarding the above-mentioned ignition coil, as the pressure of internal combustion engines has recently become higher, an increase in pressure voltage and discharge energy is required. For this reason, it is necessary to take measures such as increasing the cross-sectional area of the core and increasing the number of turns of the secondary coil wound around the core, but this would result in a larger ignition coil, which goes against the demand for miniaturization of the ignition device as a whole. becomes.

Utility Model Application Publication No. 48-49425 also explains that in order to increase the output voltage of the secondary coil, it is necessary to increase the number of windings in the secondary coil or increase the magnetic flux passing through the magnetic core. ing. As a means to solve this problem, the publication proposes an ignition coil in which a magnet having a magnetizing force in the opposite direction to the direction of magnetization generated when the switch is closed is inserted into the magnetic path. Similarly, Japanese Patent Publication No. 41-2082 discloses an ignition coil in which a permanent magnet is provided in the magnetic path of an iron core, which provides a magnetic flux different from the magnetic flux of the primary coil, that is, a magnetic flux in the opposite direction. Other Tokukai Showa 5
No. 9-167008 and Japanese Unexamined Patent Publication No. 50-218810 also disclose ignition coils in which permanent magnets are arranged in gaps provided in the core.

In any of the above-mentioned conventional technologies, one or two gaps are formed in a core around which a primary coil and a secondary coil are wound, other than the part where both coils are wound, and a permanent magnet is placed in this gap. We are planning to intervene.

[Problem to be solved by the invention] As described above, in the ignition coil in which a permanent magnet is inserted in the magnetic path, the change in magnetic flux when the primary current is interrupted is large, and the output voltage generated in the secondary coil is higher than that of the previous ignition coil. It is larger than the coil. However, in these ignition coils, since there is a large amount of leakage magnetic flux generated when the primary coil is energized, much of the increased magnetic flux is canceled out, and the increase in magnetic flux is small. Japanese Utility Model Application Publication No. 48-49425 also discloses an ignition coil equipped with two permanent magnets, but both of them are provided in the outer part of the core at a position farthest from both ends of the coil, causing leakage magnetic flux. There is no consideration given to

SUMMARY OF THE INVENTION The present invention relates to an ignition coil installed in an internal combustion engine, and an object of the present invention is to suppress leakage of magnetic flux and increase output voltage without increasing the size of the ignition coil.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an ignition coil for an internal combustion engine that induces a high voltage in a secondary coil by intermittent current flowing through some of the coils. a permanent magnet of the same number as the predetermined number, which is arranged substantially at the midpoint of a portion equally divided into a predetermined number in the axial direction, and which generates a magnetic flux in the opposite direction to the magnetic flux produced by the primary coil; It is provided with an inner core made up of a plurality of core members adjacent to each other via permanent magnets, and an outer core joined to both ends of the inner core and arranged around the primary coil and the secondary coil.

The inner core and the outer core may be integrally joined.

When the number of permanent magnets is even, the inside of the primary coil may be equally divided into the number of permanent magnets plus one. For example, when three core members of equal size are joined in the axial direction and partially accommodated in a coil, a permanent magnet may be inserted at the joint between the central core member and the core members on both sides. may be configured.

[Operation] In the ignition coil of the present invention configured as described above, the inner core is composed of a plurality of core members partially housed within the coil, and there is a gap between adjacent core members within the primary coil. A permanent magnet is inserted in each. This permanent magnet is arranged approximately at the midpoint of a predetermined number of equal parts in the primary coil in the axial direction, and is arranged so as to generate magnetic flux in the opposite direction to the magnetic flux generated by the primary coil.

As a result, the primary current supplied to the primary coil is intermittent, causing magnetic flux changes in the inner core and outer core, and a high voltage is induced in the secondary coil.

At this point, due to the presence of the magnetic flux of the permanent magnet, the change in the intersecting magnetic flux of the secondary coil becomes large, and the output voltage becomes small. Moreover,
Since some of the permanent magnets are placed at appropriate positions within the coil, local magnetic saturation is eliminated, leakage magnetic flux is reduced, and a predetermined intersecting magnetic flux is ensured for the secondary coil.

[Embodiments] Hereinafter, preferred embodiments of the ignition coil of the present invention will be described with reference to the drawings.

1 to 3 show an embodiment of the ignition coil of the present invention, in which the ignition coil 1 has an inner core 10 partially wound with a coil 21 and a secondary coil 22; It includes permanent magnets 18, 19, and forms a closed magnetic path with the outer core 14, 15. The primary coil 21 is partially wound around the bobbin 23, and the secondary coil 22 is wound around the secondary bobbin 24.
is wrapped around. Primary bobbin 23 and secondary bobbin 24
The spools are formed of synthetic resin into spools having a small diameter and a large diameter, respectively, and after a coil winding is wound around each spool, the former is formed so as to be accommodated in a hollow portion of the latter. The secondary bobbin 24 is formed with a plurality of flanges 24a, and the coil windings of the secondary coil 22 are divided into parts while maintaining a connection relationship with each other through the notches 24b of the flanges 24a shown in FIG. It is wrapped.

The inner core 10 in this embodiment includes three core members 11,
12 and 13, and permanent magnets 18 and 19 are interposed between mutually adjacent core members. Permanent magnet 18.19
is set so that the inside of the primary coil 21 is arranged approximately at the midpoint of the portions (in this embodiment, the portions are divided into three equal parts) into which the inside of the primary coil 21 is equally divided in the axial direction. That is, as shown in FIG.
8.19 are arranged, and rectangular core members 11, 12.13 are provided adjacent to each other via these. Therefore, as shown in FIG. 1, the core member 12 has an axial length 21
The core members 11 and 13 have an axial length of 1 and are arranged such that one end of each core member projects outward from the primary coil 21. The permanent magnets 18 and 19 generate magnetic flux in the same direction, and the primary coil 21
The magnetic flux is arranged in the opposite direction to the direction of the magnetic flux formed in the inner core 10 when energized. In addition, permanent magnet 18.1
9 has the same thickness, which is half the thickness required when one permanent magnet is provided.

The primary bobbin 23 is formed by placing the core member 11, the permanent magnet 18, the core member 12, the permanent magnet 19, and the core member 13 in order in a resin molding die (not shown), and then performing insert molding with a synthetic resin. be done. Then, the protruding ends 11a, 13a of the core member 11.13 are grasped, and the coil winding of the primary coil 21 is wound around the primary bobbin 23. These are accommodated in the hollow part of the secondary bobbin 24, around which the secondary coil 22 is separately wound in advance, and an external core 14.15 is provided around these, and the core members 11.13
is joined to. The outer cores 14 and 15 are formed in a U-shape when viewed from the front, and the end surfaces of both open ends of each of the outer cores 14 and 15 meet the core member 11.
．． The protruding end portions 11a and +3a of 13 are joined to the side surfaces of +3a and are magnetically coupled. Thereby, the inner core 10 includes permanent magnets 18.19 and together with the outer core 14.15 substantially forms a closed magnetic circuit. These inner core 10 and outer core 1
4.15 are all constructed of a laminate of silicon steel plates.

Note that the core members 11 and 13 at both ends are connected to the outer core 14, respectively.
．． It may be formed integrally with 15. The inner core 10, outer core 14, 15, primary coil 21, and secondary coil 22 are housed in a case 30 made of synthetic resin.

One end of the primary coil 21 is connected to a battery (not shown), and the other end is connected to a control circuit (not shown), commonly known as an igniter. One end of the secondary coil 22 is connected to the battery together with one end of the primary coil 21, and the other end is in a secondary connector 32 (not shown) integrally molded in the case 30! It is electrically connected to a spark plug (not shown) or a power distributor (not shown). Then, a thermosetting synthetic resin is filled into the case 30 and hardened to form a resin portion 31. As a result, the primary coil 21 and the secondary coil 22 are impregnated and fixed, and insulation that can withstand the high voltage output from the secondary coil 22 is ensured.

A control circuit (not shown) supplies a primary current to the primary coil 21 of the ignition coil 1 configured as described above, and when this is interrupted at a predetermined frequency, the inner core 10 including the permanent magnets 18, 19 and the outer core 14. A magnetic flux change occurs at 15. As a result, a predetermined high voltage is generated in the secondary coil 22, and this high voltage is supplied to the spark plug from the secondary connector 32 directly or via a power distributor. In this case, a large effective magnetic flux change can be ensured by the permanent magnets 18.19 interposed between the core members 11.1213 of the inner core 10. Moreover, in this embodiment, as schematically shown in FIG. 4(C), the permanent magnet 18.1
Since the permanent magnet 9 is placed approximately at the midpoint of dividing the inside of the primary coil 21 into thirds in the axial direction, the permanent magnets 18 and 19 are arranged as shown in FIG. 4(A).
The leakage magnetic flux is smaller than when it is concentrated in the center of the primary coil 21 as shown in FIG. 4, or it is separated at both ends as shown in FIG. Magnetic saturation disappears. Therefore, the magnetic flux densities of the inner core 10 and the outer core 14.15 become equal to the magnetomotive force caused by the energization of the primary current, and the discharge energy becomes the maximum as shown in the measurement results of this example in C of Fig. 5. ing. Furthermore, since the magnetic flux change becomes large, the output type pressure of the secondary coil 22 becomes large. Note that the core 10a in FIGS. 4(A) to (E) is the inner core 10 and outer core 14, 15 in FIG.
In addition, A to E in FIG. 5 indicate the output characteristics of the ignition coils in (A) to (E) in FIG. 4, respectively, and the vertical axis is the discharge energy (mJ).

In addition, when an even number of permanent magnets are arranged as in this embodiment, part of the coil 21 is evenly spaced by the number of permanent magnets plus one, as shown in FIG. 4(B). divided position,
That is, in this embodiment, if the permanent magnets are arranged at positions divided into three equal parts, the discharge energy (indicated by C in FIG. 5) in the case of FIG. Equivalent discharge energy can be obtained.

In the above embodiment, two permanent magnets are provided, but if one or three permanent magnets are provided, some of the permanent magnets in the coil 21 as shown in FIGS. 6 and 8 may be used. The output characteristics of the secondary coil 22 depending on the arrangement are shown in FIGS. 7 and 9, respectively. First, in an ignition coil in which only one permanent magnet 17 is disposed within the primary coil 21, when the permanent magnet 17 is partially disposed in the axial center of the coil 21 as shown in FIG. 6(C). discharge energy is maximum. That is, the discharge energy of the ignition coil (indicated by A in FIG. 7) in which the permanent magnet 17 is arranged only at the end of the primary coil 21 as shown in FIG. 6(A), and the discharge energy as shown in FIG. 6(B). In contrast to the discharge energy of the ignition coil (indicated by B in FIG. 7) in which the permanent magnet 17 is placed on the end side of the position where the primary coil 21 is divided into four equal parts in the axial direction, the discharge energy in FIG. 6 (
C) The discharge energy of the ignition coil (indicated by C in FIG. 7) shows the largest value.

Further, when three permanent magnets 171819 are partially arranged inside the coil 21 as shown in FIG. 8, the pressure characteristics are as shown in FIG. 9. That is, as shown in FIG. 8(A), permanent magnets 17, 18 .
The discharge energy of the ignition coil 19 (indicated by A in FIG. 9) and the primary coil 2 as shown in FIG.
In contrast to the discharge energy of the ignition coil (indicated by C in Fig. 9) in which permanent magnets 17.18°19 are arranged centrally in the axial direction within the primary coil as shown in Fig. 8 (B), 2
Permanent magnets 17, 18 .
19 is arranged, the discharge energy becomes maximum as shown by B in FIG. In addition, permanent magnets 17, 18, 19
The thickness of the permanent magnet 17 is the same as that of the part where only one permanent magnet 17 is provided as shown in FIG.

[Effects of the Invention] Since the present invention is configured as described above, it produces the effects described below.

That is, according to the ignition coil of the present invention, an internal core made up of a plurality of core members is housed in the primary coil, and permanent magnets are provided between adjacent core members, so that the magnetic flux of the secondary coil is reduced. The change in is large, and a large output voltage can be obtained. Furthermore, since the permanent magnets are partially arranged at appropriate positions within the coil, local magnetic saturation is eliminated, leakage magnetic flux is reduced, and the above output voltage is ensured. Therefore, even if, for example, the ignition coil is installed near a magnetically responsive signal generator, there is no risk that the signal generator will malfunction, and a stable output signal can be ensured. Furthermore, since leakage of magnetic flux can be suppressed without providing any special members, the ignition coil does not become large.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an ignition coil according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line II--II in FIG. 1, FIG. 3 is a cross-sectional view taken along the line III--III in FIG. Ward (A). (B), (C), (D) and (E) are front views schematically showing examples of arrangement when two permanent magnets are provided in a part of the coil, including an ignition coil according to an embodiment of the present invention. Figure 5 is the 4th
Graphs showing the discharge energy of the ignition coil in each arrangement example shown in the figure, Figures 6 (A), (B), and (C) schematically show an arrangement example when one permanent magnet is provided in the primary coil. A front view, FIG. 7 is a graph showing the discharge energy of the ignition coil in each arrangement example of FIG. 6, and FIGS. 8(A) and (B
), (C) is a front view schematically showing an arrangement example when three permanent magnets are provided in the primary coil, and Fig. 9 is a graph showing the discharge energy of the ignition coil in each arrangement example in Fig. 8. It is. 1...Ignition coil, 10...Inner core 11.1
2.13... Core member. 14.15...External core. 17.18.19...Permanent magnet. 21...Primary coil, 22...Secondary coil 23
...Primary bobbin, 24...Secondary bobbin.

Claims (2)

[Claims] (1) In an ignition coil for an internal combustion engine that induces a high voltage in a secondary coil by intermittent current flowing through the primary coil, the primary coil is arranged approximately at the midpoint of a predetermined number of equal parts in the axial direction. and an inner core comprising a number of permanent magnets equal to the predetermined number that generate magnetic flux in a direction opposite to the magnetic flux generated by the primary coil, and a plurality of core members housed within the primary coil and adjacent to each other via the permanent magnets; An ignition coil for an internal combustion engine, comprising an outer core joined to both ends of the inner core and arranged around the primary coil and the secondary coil. (2) The ignition coil for an internal combustion engine according to claim 1, wherein the inner core and the outer core are integrally joined.