JPH10303047A - Ignition coil for internal combustion engine - Google Patents

Abstract

(57) [Problem] To provide an ignition coil that generates a desired high voltage without increasing the physique. SOLUTION: In a housing 11 of a stick-shaped ignition coil 10, a central core 15, a secondary spool 20, a secondary coil 21, a primary spool 23, a primary coil 24, and an outer core 25 are arranged in this order from the center to the outer periphery. Housed in. The outer peripheral core 25 is formed by winding a thin oriented silicon steel sheet 25a having a thickness of 0.27 mm or less into a three-tube shape.
Thereby, the magnetic flux flowing through the magnetic circuit formed by the center core 15 and the outer peripheral core 25 can be increased without increasing the size of the ignition coil, and a secondary voltage value required for the ignition coil can be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition coil for an internal combustion engine, and more particularly to a stick-shaped ignition coil for an internal combustion engine directly mounted on a plug hole.

[0002]

2. Description of the Related Art Conventionally, Nippondenso public reference number 26-
As disclosed in Technical Report No. 053 and Nippon Denso Publication No. 32-039, the direction toward the core of a resin-molded closed magnetic circuit ignition coil for an internal combustion engine (hereinafter, the “ignition coil for an internal combustion engine” is referred to as an ignition coil). Some are known to have sex. By giving directionality to the silicon steel sheet that composes the core, a high voltage that satisfies the required performance can be generated on the secondary side even if the cross-sectional area of the core is smaller than that of a core using a non-oriented silicon steel sheet. The size of the coil can be reduced.

On the other hand, a rod-shaped central core is provided at the center of the shaft,
A conventional stick-shaped internal combustion engine ignition coil with a resin spool with a primary coil and secondary coil wound on its outer periphery and an outer core on its outer periphery does not use a directional silicon steel sheet and is non-directional. One or two silicon steel sheets were stacked to form an outer core. This is because in the case of a stick-shaped ignition coil, there is no advantage in reducing the diameter of the ignition coil as long as the diameter of the plug hole is not reduced, and the required performance can be satisfied without giving directionality to the outer core. .

[0004]

However, with the recent demand for improved vehicle performance and reduced fuel consumption, it has been required to generate a high secondary voltage in the stick-shaped ignition coil to reliably burn the fuel. I have. In order to generate a high secondary voltage without increasing the physique, it is an issue how to increase the magnetic flux passing through a magnetic circuit formed by the center core and the outer core.

An object of the present invention is to provide an ignition coil that generates a desired high voltage without increasing the size.

[0006]

According to the ignition coil according to the first aspect of the present invention, the outer peripheral core disposed on the outer periphery of the primary coil and the secondary coil is made of three or more silicon steel sheets,
In addition, by configuring two or more of them with oriented silicon steel sheets, the magnetic flux passing through the magnetic circuit formed by the center core and the outer core is increased. Thus, a higher secondary voltage can be generated in the secondary coil without increasing the size of the ignition coil.

According to the ignition coil of the present invention, by reducing the thickness of the grain-oriented silicon steel sheet to 0.27 mm or less, the eddy current generated in each silicon steel sheet is reduced, and the eddy current of the outer peripheral core is reduced. Reduce losses. Thereby, a higher secondary voltage can be generated in the secondary coil.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1, 2 and 3 show a stick-shaped ignition coil according to an embodiment of the present invention. The ignition coil 10 shown in FIG. 2 is housed in a plug hole formed for each cylinder above an engine block (not shown), and is electrically connected to an ignition plug (not shown) on the lower side of FIG.

The ignition coil 10 has a cylindrical housing 11 made of a resin material. A center core 15 and a magnet 1 are housed in a housing chamber 11a formed in the housing 11.
6, 17, the secondary spool 20, the secondary coil 21, the primary spool 23, the primary coil 24, the outer core 25 and the like are accommodated. The epoxy resin 26 as a resin insulating material filled in the accommodating chamber 11a penetrates between each member in the ignition coil 10 to ensure electrical insulation between the members as a resin insulating material.

The cylindrical central core 15 is assembled by laminating thin silicon steel plates in the radial direction so that the cross section is substantially circular. Magnets 16 and 17 having polarities opposite to the direction of the magnetic flux generated by the excitation of the coils are mounted on both ends of the central core 15 in the axial direction. The outer periphery of the center core 15 is covered with a rubber material 18 as an insulating material.

As shown in FIG. 1, the secondary spool 20 is provided on the outer periphery of the rubber member 18 and is formed of a resin material. The secondary coil 21 is wound around the outer periphery of the secondary spool 20, and a dummy coil 22 is further wound around the high voltage side of the secondary coil 20 in a single winding. The dummy coil 22 includes the secondary coil 21 and the terminal plate 40.
And are electrically connected. By electrically connecting the secondary coil 21 and the terminal plate 40 with the dummy coil 22 instead of a single wire, the surface area of the electrical connection between the secondary coil 21 and the terminal plate 40 is increased,
Avoids electric field concentration on electrical connections.

The primary spool 23 is provided on the outer periphery of the secondary coil 21 and is formed of a resin material. The primary coil 24 is wound around the outer periphery of the primary spool 23,
It is electrically connected to a switching circuit (not shown) via a terminal 31 shown in FIG. The outer core 25 is mounted further outside the primary coil 24. FIG. 3 shows a configuration example of the outer core 25. The outer core 25 has a thickness of 0.
Since a thin directional silicon steel sheet 25a of 27 mm or less is wound in a three-tube shape and the winding start end and the winding end end are not connected, a gap 25b is formed in the axial direction. The gap 25b is formed so that no current due to magnetic flux is generated in the circumferential direction of each directional silicon steel sheet 25a. The outer core 25 is a magnet 16
Has an axial length extending from the outer peripheral position of the magnet 17 to the outer peripheral position of the magnet 17.

A connector 3 for inputting control signals shown in FIG.
Numeral 0 is provided at the upper end of the housing 11 so as to protrude from the plug hole, and a terminal 31 for supplying a control signal to the primary coil 24 is insert-molded in the connector 30. A switching circuit for supplying a control signal to the primary coil 24 via the terminal 31 is provided outside the ignition coil 10.

As shown in FIG. 2, the high-voltage terminal 41 is insert-molded at the lower end 11b of the housing 11. The central portion of the terminal plate 40 forms a claw portion bent in the direction in which the high-voltage terminal 41 is inserted. By inserting the tip of the high-voltage terminal 41 into this claw portion, the high-voltage terminal 41 is electrically connected to the terminal plate 40. The wire at the high voltage end of the dummy coil 22 is electrically connected to the terminal plate 40 by fusing or soldering. The spring 42 is electrically connected to the high voltage terminal 41 and is electrically connected to the ignition plug when the ignition coil 10 is inserted into the plug hole. A plug cap 19 made of rubber is attached to the open end of the housing 11 on the high voltage side, and an ignition plug is inserted into the plug cap 19. When a control signal is supplied from the switching circuit to the primary coil side, a high voltage is generated in the secondary coil 21, and this high voltage is applied to the ignition plug via the dummy coil 22, the terminal plate 40, the high voltage terminal 41, and the spring 42. .

Next, FIG. 4 and Table 1 show the relationship between the number and thickness of the grain-oriented and non-oriented silicon steel sheets and the secondary voltage generated in the secondary coil 21. In FIG. 4, the characteristics indicated by black circles are those of an ignition coil in which the thickness of the outer peripheral core is set to about 1 mm and an aluminum plug tube is attached. .7mm,
The ignition coil is equipped with an iron plug tube. Further, Table 1 shows the thickness of each silicon steel sheet constituting the outer core, and details of the directionality or non-direction. The secondary voltage required for the ignition coil is set to 36 kV in consideration of the variation in the entire ignition system to the maximum required voltage value required from engine performance.

[0016]

[Table 1]

As can be seen from FIG. 4 and Table 1, regardless of the material of the plug tube, if the outer peripheral core is constituted by using three or more silicon steel sheets, and using at least two or more of the oriented silicon steel sheets, A voltage value higher than the secondary voltage required for the ignition coil can be generated. If the number of silicon steel sheets constituting the outer core is the same, the secondary voltage value increases as the number of directional silicon steel sheets increases, and if the thickness of the outer core is the same, the number of directional silicon steel sheets increases and the thickness increases. The thinner the secondary voltage, the higher the secondary voltage. The thickness of each grain oriented silicon steel sheet is 0.
It is desirable that it is 27 mm or less.

In the above-described embodiment of the present invention, the outer core 25 is made of three silicon steel sheets, and at least two of the outer cores are made of directional silicon steel sheet. 25 increases the magnetic flux passing through the magnetic circuit which is neglected. Thereby, the secondary voltage generated in the secondary coil 21 can be increased without increasing the size of the ignition coil 10.

Further, the thickness of each grain-oriented silicon steel sheet is set to 0.2
By setting the thickness to 7 mm or less, eddy current loss generated in the grain-oriented silicon steel sheet can be reduced, and a high voltage can be generated in the secondary coil 21 more efficiently.

[Brief description of the drawings]

FIG. 1 shows an ignition coil according to one embodiment of the present invention.
It is an enlarged view of the I line part.

FIG. 2 is a longitudinal sectional view showing an ignition coil according to the embodiment.

FIG. 3A is a front view showing an outer peripheral core of the present embodiment, and FIG. 3B is a sectional view taken along line BB of FIG. 3A.

FIG. 4 is a characteristic diagram showing the number, thickness, presence / absence of directionality, and secondary generation voltage of silicon steel sheets constituting an outer core.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ignition coil 15 Center core (core) 20 Secondary spool 21 Secondary coil 23 Primary spool 24 Primary coil 25 Outer core 25a Oriented silicon steel sheet

Claims (2)

[Claims] 1. An internal combustion engine ignition coil for generating a high voltage applied to an internal combustion engine ignition device, comprising: a rod-shaped central core; a primary coil and a secondary coil wound around an outer periphery of the central core. An outer peripheral core disposed on the outer periphery of the primary coil and the secondary coil and configured of three or more silicon steel plates, wherein at least two or more of the silicon steel plates are configured of directional silicon steel plates; An ignition coil for an internal combustion engine, comprising: a core; 2. The grain thickness of the grain-oriented silicon steel sheet is 0.27 mm.
The ignition coil for an internal combustion engine according to claim 1, wherein: