JPH10321447A - Ignition coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve energy transfer efficiency in a series winding type ignition coil. SOLUTION: With a permanent magnet 6 disposed near an end part of a secondary coil part 5 farther from a primary coil part 3, an auxiliary magnetic field in the same direction as a primary magnetic field excited with the primary coil part 3 is formed, and a magnetic flux about to diverge at the end part of the secondary coil part 5 is attracted with the auxiliary magnetic field, to raise magnetic flux density extending over the entire secondary coil part 5. The magnetic flux is changed under this condition, to raise energy transfer efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ignition coil for an independent ignition system used in an internal combustion engine.

[0002]

2. Description of the Related Art As shown in FIG. 3, an ignition coil of this type includes a magnetic core 21 on which electromagnetic steel plates are laminated, a primary winding bed 22 attached to the magnetic core 21, and a primary winding floor 22. A primary coil part 23 formed by winding an enamel wire as a primary winding, a secondary winding floor 24 fitted outside the primary winding floor 22 on which the primary coil part 23 is formed,
A secondary coil portion 25 formed by winding an enamel wire as a secondary winding around the secondary winding bed 24 is provided (first conventional technology). The ignition coil is housed in a predetermined case, filled with a thermosetting resin such as an epoxy resin by vacuum injection, and the primary coil portion 23 and the secondary coil portion 25 are impregnated and fixed to each other by the thermosetting resin. In addition, the insulation property to withstand the output high voltage of the secondary coil unit 25 is ensured.

In the ignition coil configured as described above, only a connector (not shown) disposed at the lower end is fixed in a state of being inserted into a predetermined plug hole of the internal combustion engine and protruding above the internal combustion engine. You.

[0004]

Incidentally, since the ignition coil of the above type is mounted so as to protrude from the upper surface of the internal combustion engine, it occupies the installation space on the upper surface side of the internal combustion engine. However, there is a demand to save as much space as possible on the upper surface side of the internal combustion engine in relation to other parts such as a duct of the inlet manifold.

Therefore, recently, there has been an attempt to install the entire ignition coil in a plug hole as a countermeasure.
However, in the conventional ignition coil, since the primary coil portion 23 and the secondary coil portion 25 are concentrically arranged, the outer diameter of the coil becomes large, and it is difficult to insert the entire coil into the plug hole. .

In consideration of such a situation, in order to reduce the diameter of the coil, as shown in FIG. 4, a system in which a primary coil unit 23 and a secondary coil unit 25 are arranged in series (series winding system: 2
Prior art). However, in the case of this series winding method, the density of the magnetic flux generated in the primary coil portion 23 is dense near the primary coil portion 23, but is farther from the primary coil portion 23 of the secondary coil portion 25. In 26, the magnetic flux density decreases due to the divergence of the magnetic flux passing through the magnetic core 21. As a result, at the end portion 26 of the secondary coil portion 25, the energy transmission efficiency from the primary coil portion 23 is reduced, and the ignition coil as a whole is more conspicuous than when it is arranged concentrically as shown in FIG. Energy loss of more than 20%.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an ignition coil that can alleviate a decrease in energy transmission efficiency when a series winding system is employed.

[0008]

SUMMARY OF THE INVENTION The present invention provides a magnetic core formed of a magnetic material, a primary coil portion wound around an outer peripheral portion of the magnetic core adjacent to each other in an axial direction of the magnetic core, and A secondary coil portion, and an auxiliary coil disposed near an end of the secondary coil portion remote from the primary coil portion to form an auxiliary magnetic field (permanent magnetic field) in the same direction as the primary magnetic field excited by the primary coil portion. The auxiliary magnetic field forming means is a permanent magnetic field which is particularly inexpensive and easy to handle.

Thus, the magnetic flux to be diverged at the end of the secondary coil portion can be attracted by the permanent magnet, and a change in the magnetic flux is given over the entire secondary coil portion, so that the magnetic flux changes from the primary coil portion to the secondary coil portion. The energy transmission efficiency to the part can be easily improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ignition coil according to one embodiment of the present invention is a series-wound type ignition coil in which a primary coil portion and a secondary coil portion are arranged in series, and an end of the secondary coil portion. The magnetic flux that is going to diverge in the part is attracted and converged by the permanent magnet, and the magnetic flux is changed in this state, thereby improving the energy transfer efficiency of the primary side and the secondary side.

FIG. 1 is a sectional view showing an ignition coil according to this embodiment. As shown in FIG. 1, this ignition coil includes a magnetic core 1 as a magnetic material made of an electromagnetic soft iron bar or an amorphous alloy foil of Fe-Si-B or the like, and a winding bed 2 fitted outside the magnetic core 1. A primary coil 3 and a secondary coil 5 arranged in series by winding enameled wires 3a and 5a as windings around the winding bed 2, and a primary coil of the secondary coil 5 of the magnetic core 1; A permanent magnet 6 fixed to an end remote from the part 3 (hereinafter, simply referred to as “far end”).

The winding bed 2 is formed into a substantially cylindrical shape by molding or the like using an industrial plastic material such as polybutylene terephthalate (PBT), polyphenylene oxide (PPO) or polyphenylene ether (PPE). The primary bobbin 2a for forming the primary coil 3 and the secondary bobbin 2b for forming the secondary coil 5 are arranged in series and integrally formed. On both ends of the wound bed 2 and on the outer surface of the boundary between the primary side bobbin 2a and the secondary side bobbin 2b, flanges 7a to 7b project radially to demarcate the boundaries of the coils 3,5. 7c is formed. A plurality of flanges 7d are formed on an outer surface of the secondary bobbin 2b so as to project in a radial direction at regular intervals to partition a plurality of winding regions (sections).

The primary enameled wire 3a of the primary coil section 3
For example, the outer periphery of a core portion made of copper or the like, a diameter of 0.4 in which an insulating inner layer formed of polyester, polyesterimide, or polyimide, and an insulating outer layer formed of polyamideimide, polyester, or the like are sequentially laminated and coated. A magnet wire of about 0.6 mm is used. On the other hand, the secondary side enameled wire 5a of the secondary coil portion 5
For example, a magnet wire or the like having a medium heat resistance of about 0.04 to 0.06 mm in diameter is used, and is section-wound in a plurality of winding areas partitioned by a flange 7d.

The permanent magnet 6 contains a rare earth element such as Nd-Fe-B or Sm-Co as one component, and generates a magnetic field in the same direction as the magnetic field generated when the primary coil 3 is energized. Be placed.

FIG. 2 is a view showing a state in which the ignition coil A1 is mounted in the plug hole 13 of the internal combustion engine. As shown in FIG. 2, it is connected to a battery unit (not shown) via a switch unit 15 and a primary lead 16. On the other hand, a secondary connector 17 is attached to the lower end of the ignition coil A1 and is connected to an ignition plug at the back of the plug hole 13. Reference numeral 19b in FIG. 2 indicates a rain cover, and 19c indicates a rubber bush.

In the above-described ignition coil, first, power is supplied from a battery unit (not shown) through a primary lead wire 16 and, when the switch unit 15 is turned on, a current flows through the primary enamel wire 3a of the primary coil unit 3. , The magnetic core 1 is magnetized to form a magnetic field.

The magnetic field formed at this time is applied to the primary coil 3
However, the magnetic field formed from the primary coil portion 3 to the secondary coil portion 5 is attracted by the permanent magnet 6 attached to the far end of the secondary coil portion 5 and converges. Formed at the far end.

At this point, the switch unit 15 is suddenly turned off.
When F is set, the magnetic field rapidly changes in magnetic flux. As described above, the magnetic field that changes at this time also changes from the state where the magnetic flux is converged by the permanent magnet 6 even at the far end of the secondary coil section 5, so that the magnetic flux changes from the primary coil section 3 to the secondary coil section. This is reflected on everything up to the far end of the part 5. as a result,
The back electromotive force specific to the inductor is generated efficiently, and this is boosted at a primary: secondary turns ratio, and a high voltage of, for example, 30 kV is generated in the secondary coil unit 5, and a current is generated in the secondary enameled wire 5a. Flows. Power can be supplied to the ignition plug by this current.

Since a permanent magnetic field is formed in advance by the permanent magnet 6, the initial magnetization state approaches a saturation state from the origin of the magnetization curve. In this case, the back electromotive force in the secondary coil unit 5 However, if the saturation point is moved away from the initial magnetized state by setting the diameter of the magnetic core 1 to a large value, a decrease in energy transfer efficiency can be avoided.

As described above, in the series-wound ignition coil, the change in the magnetic flux that is about to diverge at the end of the secondary coil portion 5 is attracted by the permanent magnet 6, so that the change in the magnetic flux is reduced by the secondary coil portion. 5, so that the energy transfer efficiency of the secondary side can be easily improved. here,
Since the permanent magnet 6 is inexpensive and convenient to handle, the labor and burden on the manufacturing site are minimized.

In the above-described embodiment, an electromagnetic soft iron rod or an amorphous alloy foil is used as the magnetic core 1. However, the present invention is not limited to such a configuration. For example, a plurality of wires are bound by a binding device. May be applied, or a conventional electromagnetic steel plate may be used.

The primary enameled wire 3a and the secondary enameled wire 5a are not limited to the above configuration, but may be any material having an insulating organic film having high heat resistance or the like. For example, it may be formed by coating a tube formed of an insulating material, applying a liquid resin, or molding with an insulating resin.

[0023]

According to the first aspect of the present invention, the auxiliary magnetic field forming means disposed near the end far from the primary coil portion of the secondary coil portion is the same as the primary magnetic field excited by the primary coil portion. Since the auxiliary magnetic field in the direction is formed, the change in magnetic flux that is going to diverge at the end of the secondary coil portion can be attracted by the auxiliary magnetic field generated by the auxiliary magnetic field forming means, and the entire secondary coil portion can be attracted. The magnetic flux density can be increased over the entire area. Therefore, when a magnetic flux change occurs, this magnetic flux change can be sensed in the entire secondary coil portion,
Therefore, the energy transfer efficiency from the primary coil to the secondary coil can be easily improved.

According to the second aspect of the present invention, a permanent magnet which is inexpensive and easy to handle is used as the auxiliary magnetic field forming means. Is minimized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an ignition coil according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which an ignition coil according to one embodiment of the present invention is mounted in a plug hole of an internal combustion engine.

FIG. 3 is a sectional view showing a first prior art ignition coil.

FIG. 4 is a sectional view showing a second prior art ignition coil.

[Description of Signs] 1 Magnetic core 2 Rolling floor 2a Primary bobbin 2b Secondary bobbin 3 Primary coil 3a Primary enameled wire 5 Secondary coil 5a Secondary enameled wire 6 Permanent magnet 7a to 7d Collar

Claims (2)

[Claims] A magnetic core formed of a magnetic material, a primary coil portion and a secondary coil portion wound adjacent to each other in an axial direction of the magnetic core at an outer peripheral portion of the magnetic core; An auxiliary magnetic field generating means disposed near an end of the secondary coil portion remote from the primary coil portion so as to form an auxiliary magnetic field in the same direction as the primary magnetic field excited by the coil portion. coil. 2. The ignition coil according to claim 1, wherein the auxiliary magnetic field forming means is configured to generate a permanent magnetic field in the same direction as a primary magnetic field excited by the primary coil part. An ignition coil, wherein the ignition coil is a permanent magnet arranged near an end far from the primary coil.