JP4068693B2 - Ignition coil for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ignition coil for an internal combustion engine for generating spark discharge in an ignition plug of an automobile internal combustion engine, and more particularly to an ignition coil for an internal combustion engine mounted in a plug hole formed in an engine block.
[0002]
[Prior art]
Conventionally, as an ignition coil for an internal combustion engine mounted in a plug hole of an internal combustion engine, a primary coil 4A, a secondary coil 6A, and the two coils 4A and 6A are magnetically coupled as shown in FIG. A cylindrical central iron core 2A is disposed inside the cylindrical case 7A, and magnetic lines 20A generated from both ends of the central iron core 2A flow in to form an open magnetic path with the central iron core 2A. There is known an ignition coil 1A for an internal combustion engine in which an iron core 11A is arranged on the outer periphery of a case 7A.
[0003]
Since the internal combustion engine ignition coil 1A is planned to be used in a thin and long plug hole (not shown) formed in the engine block, a dimensional restriction is inevitably generated, and the plug hole In relation to the inner diameter, the outer diameter of the insulating case 7A is kept to about 25 mm even if it is thicker from 22 mm.
[0004]
[Problems to be solved by the invention]
As described above, in the above-described conventional ignition coil 1A for an internal combustion engine, the outer diameter of the case 7A is restricted, and consequently, the sectional area of the central core 2A, the winding sectional areas of the primary coil 4A, and the secondary coil 6A are also restricted. Accordingly, sufficient ignition energy could not be obtained unless the coil portion composed of the central iron core 2A, the primary coil 4A and the secondary coil 6A is made long to secure the number of turns.
[0005]
Further, since the magnetic circuit is an open magnetic circuit, the magnetic efficiency is poor, and even if the permanent magnets 14A and 14A are provided at both ends of the central iron core 2A and the magnetic reverse bias is applied, there is a limit in improving the performance. Therefore, sufficient ignition energy could not be obtained unless the coil portion was made long.
[0006]
On the other hand, since the ignition coil 1A for an internal combustion engine is required to have high heat resistance and repeated heat and cold resistance, it is filled with a high heat-resistant thermosetting resin 12A to insulate each member. Due to the difference in thermal expansion between 5A and the insulating case 7A and the thermosetting resin 12A during the cooling, a tensile stress in the length direction (arrow M in FIG. 3) is generated in the coil portion during repeated cooling, and the tensile stress generates heat. Cracks may occur in the curable resin 12A. The conventional ignition coil for internal combustion engine 1A has a problem that since the length of the coil portion is long, the possibility of occurrence of cracks is particularly great, and the reliability as a product is impaired.
[0007]
The present invention has been proposed in view of the above. An ignition coil for an internal combustion engine that can obtain sufficient ignition energy even when the length of the coil portion is shortened and does not generate cracks in the filled thermosetting resin. The purpose is to provide.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the ignition coil for an internal combustion engine of the present invention has a primary coil and a secondary coil concentrically with the central iron core, which are fixed inside an insulating case injected with a thermosetting resin. is further made with a sheath core in their concentric relationship, spark plug from the outer diameter of 22mm to 25 mm, and the ignition coil mounting surface of the main body portion for use in housed in the plug hole drilled in the engine block In an internal combustion engine ignition coil having a distance to the head electrode of at least 100 mm or more, a center core is provided at both ends of the central core so as to face the outer core, and the central core and a core at one end of the central core are provided. A thin disc-shaped permanent magnet having an outer diameter larger than that of the central iron core is interposed between the permanent magnet and the central iron core, and an outer diameter larger than that of the central iron core is interposed between the permanent magnet and the central iron core. To is interposed a thin disk-shaped auxiliary core, also includes a direct relay core to the other end of the central core, a closed magnetic circuit consisting of a central core → auxiliary core-permanent magnet → the relay core → outer core → the relay core → central core The length of the central iron core, primary coil, and secondary coil is 50% or less from the ignition coil mounting surface to the spark plug head electrode, and is disposed closer to the ignition coil mounting surface. It is said.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a sectional view showing a schematic configuration of an ignition coil for an internal combustion engine according to the present invention.
[0010]
In the figure, an internal combustion engine ignition coil (hereinafter referred to as “ignition coil”) 1 is of a plug hole accommodating type mounted in a plug hole of the internal combustion engine.
The cylindrical insulating case 7 is formed of an electrically insulating material such as a synthetic resin. In the insulating case 7, a magnetic metal plate represented by a silicon steel plate is provided along the central axis. A central iron core 2 formed in a cylindrical shape is accommodated, and an insulating paper 3 is wound around the outer periphery of the central iron core 2. The outer diameter of the central iron core 2 is 40 to 50% of the outer diameter of the exterior iron core described later.
The insulating paper 3 is, for example, a heat-resistant insulating paper having a thickness of 0.2 mm in which a glass base cloth is impregnated with an epoxy resin. A primary coil 4 is formed on the insulating paper 3 with a wire diameter of φ0.4 mm over a winding width of 30 mm. It is formed by winding 130 times.
[0011]
A secondary bobbin 5 made of synthetic resin and having a plurality of divided winding grooves 51 is fitted to the outer periphery of the primary coil 4. The secondary bobbin 5 including the divided winding grooves 51 is provided with a diameter of 0.04 mm. The secondary coil 6 is formed by winding 13000 times over a winding width of 30 mm with a wire diameter of 2 mm, and faces the inner peripheral surface of the insulating case 7.
[0012]
A thin cylindrical outer core 11 having an outer diameter of 22 mm to 25 mm, which is formed of a magnetic metal plate typified by a silicon steel plate, is fitted to the outer periphery of the insulating case 7.
[0013]
Further, between the lengthwise ends of the central iron core 2 and the insulating case 7, intermediate iron cores 13 and 13 are arranged so as to face the outer core 11 on the outer periphery of the insulating case 7, respectively. That is, in FIG. 1, the intermediate iron core 13 is provided on the upper end surface in the length direction of the central iron core 2 via the auxiliary iron core 15 and the permanent magnet 14, and the intermediate iron core 13 is directly provided on the lower end surface in the length direction of the central iron core 2. Each is arranged.
[0014]
As shown in FIG. 2, the intermediate iron core 13 is formed by laminating disc-shaped directional silicon steel plates having symmetrical recesses 131, 131 to a thickness of about 2 to 3 mm. The cross-sectional area in the cross section, that is, the cross-sectional area perpendicular to the magnetic path is equivalent to the circular cross-sectional area in the direction perpendicular to the axial direction of the central iron core 2. The recesses 131 of the intermediate core 13 pass through a connection line (not shown) between the primary terminal 10 and the primary coil 4 and a connection line (not shown) between the high voltage terminal 8 and the secondary coil 6. belongs to.
[0015]
Each of the permanent magnet 14 and the auxiliary iron core 15 has an outer diameter larger than that of the central iron core 2, and its horizontal cross-sectional area is twice the circular cross-sectional area of the central iron core 2 and is a thin disk-like one having a thickness of 1 mm. It is.
[0016]
A plug engaging portion 7a that protrudes concentrically is formed integrally with the insulating case 7 at the lower end of the insulating case 7, and the lower end side of the insulating case 7 is closed in the hole on the upper end side of the plug engaging portion 7a. Thus, the high voltage terminal 8 is fitted. A spring 16 is housed in the plug engaging portion 7a from the high voltage terminal 8 at the upper end to the lower end thereof. A cylindrical boot 17 is fitted on the outer periphery of the lower end, and the ignition plug protrudes from the bottom of the plug hole by inserting the cylindrical boot 17 into a plug hole (not shown) drilled in the engine block. A head electrode (not shown) is brought into contact with the spring 16 and is electrically connected to the high-voltage terminal 8.
The plug engaging portion 7a may be separated from the insulating case 7 and may be joined to the coil portion after casting the thermosetting resin 12 into the insulating case 7.
[0017]
The upper end of the insulating case 7 is opened, and the primary terminal seat 9 is provided so as to protrude from a part of the outer periphery of the upper end. A primary terminal 10 is attached to the primary terminal seat 9 through the outer wall of the insulating case 7. A power switch 18 is accommodated in the opening at the upper end of the insulating case 7, and a predetermined wiring is formed between the primary terminal 10 and the primary coil 4.
The primary terminal 10 is connected to the primary coil 4 through an inner wiring (not shown) through the recess 131 of the intermediate core 13, and the high-voltage terminal 8 is also connected to the primary coil 10 through an inner wiring (not shown) through the concave 131 of the intermediate core 13. It is connected to the next coil 6.
[0018]
An insulating thermosetting resin 12 such as an epoxy resin is injected from the opened upper end of the insulating case 7, whereby the central iron core 2, the primary coil 4, the secondary coil 6, and the power switch inside the insulating case 7. Each member such as 18 is fixed and insulation between the members is maintained.
[0019]
In use, the engine harness (plug) of the internal combustion engine is fitted to the primary terminal seat 9 to establish a predetermined electrical connection, whereby the primary coil 4 is energized according to the control on the internal combustion engine side. The high voltage generated in the secondary coil 6 in response to the interruption is supplied to the spark plug via the high voltage terminal 8 and the spring 16, and a spark is generated between the electrodes at the tip.
[0020]
Further, a coil mounting portion 30 is extended at a position opposite to the primary terminal 10 on the outer periphery of the upper end of the insulating case 7, and when the ignition coil 1 is inserted into the plug hole, the lower end surface of the coil mounting portion 30 is the engine. The ignition coil mounting surface p1 is brought into contact with the block, and the ignition coil 1 is bolted to the engine block side with a bolt inserted into a bolt hole (not shown) of the coil mounting portion 30 in the contacted state. Fix it to the side.
In the ignition coil 1, the distance L from the ignition coil mounting surface p1 to the ignition plug head electrode position p2 where the spring 16 contacts the head electrode of the ignition plug has at least 100 mm or more. The coil portion composed of the central iron core 2, the primary coil 4 and the secondary coil 6 is disposed near the ignition coil mounting surface p1 in the distance L, and the length L1 of the coil portion is 50% or less of the distance L. It has become.
[0021]
In this embodiment, since the intermediate cores 13 and 13 are provided at both ends of the central iron core 2 so as to face the outer iron core 11 as described above, the ignition coil 1 includes the central iron core 2 → the auxiliary iron core 15 and the permanent magnet 14. A closed magnetic circuit composed of the upper end side relay core 13 → the outer core 11 → the lower end side core 13 → the central core 2 is configured, and the magnetic flux generated in the primary coil 4 efficiently flows through the closed magnetic circuit without leaking. Therefore, the magnetic efficiency is greatly improved, and a large secondary energy can be obtained. Even if the length of the coil portion including the central core 2, the primary coil 4, and the secondary coil 6 is shortened, the secondary energy can be sufficiently obtained. Secondary energy can be obtained, and as a result, the coil portion is reduced in size so that its length is 50% or less of the distance L from the ignition coil mounting surface p1 to the spark plug head electrode position p2, and the ignition coil mounting It was decided to be disposed closer to the surface p1.
[0022]
Since the coil portion can be reduced in size as described above, the tensile stress in the length direction of the coil portion can be greatly reduced. Therefore, the crack of the thermosetting resin 12 is eliminated, and the reliability can be greatly improved.
[0023]
Further, since the coil portion can be disposed at one end side of the entire length of the ignition coil 1 and at a position far from the cylinder of the engine, the thermal influence on the coil portion is mitigated. The tensile stress in the direction can be reduced, and the occurrence of cracks in the thermosetting resin can be prevented.
[0024]
Further, by arranging the permanent magnet 14 and the auxiliary iron core 15 between the upper end surface of the central iron core 2 and the intermediate iron core 13, the secondary energy can be improved about four times as compared with the conventional case.
Here, in order to contribute to the downsizing of the coil portion, the permanent magnet 14 is thinned and provided only on the upper end side. On the other hand, the permanent magnet 14 has a large cross-sectional area in order to ensure the magnetic reverse bias effect. . As described above, when the cross-sectional area is increased, the flow of magnetic flux between the central iron core 2 is disturbed. In this embodiment, the auxiliary iron core 15 is interposed between the central iron core 2 and the permanent magnet 14. The flow of magnetic flux is made smooth.
[0025]
In the above description, the outer iron core 11 is provided on the outer periphery of the insulating case 7, but may be provided on the inner periphery, and in that case, the magnetic effect does not change.
[0026]
【The invention's effect】
As described above, according to the ignition coil for an internal combustion engine of the present invention, the intermediate iron core is provided at both ends of the central iron core so as to face the outer iron core, and the length of the coil portion including the central iron core, the primary coil, and the secondary coil is long. The size was reduced to 50% or less of the distance from the ignition coil mounting surface to the spark plug head electrode position, and the coil portion was arranged closer to the ignition coil mounting surface.
[0027]
By reducing the size of the coil portion in this way, the tensile stress in the length direction of the coil portion can be greatly reduced, and therefore there is no crack in the thermosetting resin, and the reliability can be greatly improved.
[0028]
In addition, since the coil part is arranged on one end of the ignition coil at a distance from the engine cylinder, the thermal effect on the coil part is alleviated. From this point, the tensile stress in the coil part length direction is also reduced. This can reduce the occurrence of cracks in the thermosetting resin.
[0029]
In addition, by arranging a permanent magnet between the central iron core and the intermediate iron core, the secondary energy can be improved to about four times the conventional energy.
[0030]
Furthermore, since the auxiliary iron core is interposed between the permanent magnet and the central iron core, even if the outer diameter of the permanent magnet is larger than the central iron core, the magnetic flux between the central iron core and the permanent magnet is not disturbed and smooth. Can be.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of an ignition coil for an internal combustion engine according to the present invention.
2A and 2B are diagrams showing a core iron core, in which FIG. 2A is a plan view, and FIG. 2B is a cross-sectional view taken along line II of FIG.
FIG. 3 is a sectional view showing a schematic configuration of a conventional ignition coil for an internal combustion engine mounted in a plug hole of the engine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ignition coil 2 Central iron core 3 Insulation paper 4 Primary coil 5 Secondary bobbin 6 Secondary coil 7 Insulation case 7a Plug engaging part 8 High voltage terminal 9 Primary terminal seat 10 Primary terminal 11 Exterior iron core 12 Thermosetting resin 13 Middle iron core 131 Concave portion 14 Permanent magnet 15 Auxiliary iron core 16 Spring 17 Cylindrical boot 18 Power switch 30 Ignition coil attachment portion p1 Ignition coil attachment surface p2 Spark plug head electrode position L Distance from ignition coil attachment surface p1 to ignition plug head electrode position p2 L1 Length of coil part

Claims (2)

It has a primary coil and a secondary coil in a concentric relationship with the central iron core, they are fixed inside the insulating case injected with thermosetting resin , and further have an outer iron core in a concentric relationship with them. In an internal combustion engine ignition coil in which an outer diameter of a main body portion used by being accommodated in a plug hole drilled in a block is 22 mm to 25 mm, and a distance from an ignition coil mounting surface to an ignition plug head electrode is at least 100 mm or more,
A center core is provided at both ends of the central core so as to face the outer core, and a thin disk-shaped permanent core having an outer diameter larger than that of the central core is provided between the central core and the core at one end of the central core. A magnet is interposed, and a thin disk-shaped auxiliary iron core having an outer diameter larger than that of the central iron core is interposed between the permanent magnet and the central iron core, and a central core is provided directly on the other end of the central iron core. Construct a closed magnetic circuit consisting of iron core → auxiliary iron core / permanent magnet → relay iron core → exterior iron core → relay iron core → central iron core,
The lengths of the central iron core, primary coil and secondary coil are 50% or less from the ignition coil mounting surface to the spark plug head electrode, and are arranged closer to the ignition coil mounting surface.
An ignition coil for an internal combustion engine. The central iron core is formed by laminating strips of directional silicon steel sheets, and formed so that the outer diameter approaches a circle. The outer diameter is 40 to 50% of the outer diameter of the main body part.
The ignition coil for an internal combustion engine according to claim 1.

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