JPH0547456Y2 - - Google Patents

Description

[Detailed description of the invention] <Field of industrial application> The present invention relates to a coil device used as an ignition coil that supplies high voltage to a spark plug of an internal combustion engine, etc. The magnetic coupling core has a cross-sectional shape that becomes thinner from the low voltage side to the high voltage side of the high voltage output coil, and by arranging the low voltage input coil along the outer periphery of the core, the gap between the low voltage input coil and the high voltage output coil is reduced. In addition to substantially increasing the insulation distance and preventing dielectric breakdown between the coils without reducing the magnetic coupling of the coils,
This allows for miniaturization.

<Prior Art> The general configuration of this type of coil device includes a magnetic circuit composed of a low-voltage input coil, a high-voltage output coil, and a core that magnetically couples both coils.
High voltage is supplied to the spark plug from the high voltage output coil. 3 to 5 are cross-sectional views of main parts of a conventional coil device, in which 1 is a core, 2 is a low-voltage input coil, and 3 is a high-voltage output coil. 4 is a bobbin around which the low voltage input coil 2 is wound, and 5 is a bobbin around which the high voltage output coil 3 is wound.

The bobbin 5 has a coil winding portion 5 partitioned along the axial direction by collar portions 51 provided at appropriate intervals.
2, and the high voltage output coil 3 is continuously wound around each coil winding portion 52. The high voltage output coil 3 extends from one end of the bobbin 5 in the axial direction toward the other end.
As shown by arrow a, since it is wound in the axial direction, one end A becomes the low pressure side and the other end B becomes the high pressure side. Then, the bobbin 4 around which the low voltage input coil 2 is wound is coaxially inserted into the inner diameter hole 53 of the bobbin 5 around which the high voltage output coil 3 is wound.
The core 1 is inserted into the inner diameter hole 41 of the bobbin 4.

In the high voltage output coil 3, one end (a) in the axial direction of the bobbin 5 is the low voltage side, and the other end (b) is the high voltage side. 3. Sufficient insulation distance must be ensured between the As a means for this, in the conventional example shown in FIG. 3, an insulation interval d1 of the same size is formed between the low voltage input coil 2 and the high voltage output coil 3 over substantially the entire length in the axial direction. In the conventional example shown in FIG. 4, the depth to the bottom of the coil winding section 52 divided by the collar section 51 of the bobbin becomes shallower toward the high voltage side. The insulation distance between the high-voltage output coil and the low-voltage input coil is set to be larger. In the conventional example shown in FIG.
It is similar to the conventional example shown in FIG. 4 in that the depth to the bottom of the coil winding section 52 divided by The difference is that the inner diameter surface is made to be moderately thick and the inner diameter surface is a non-tapered surface.

<Problems to be solved by the invention> However, the above-described conventional coil device has the following problems.

(b) Problems with the conventional technology shown in Figure 3: Because the same insulation distance as the high voltage side is secured on the low voltage side, which does not require much insulation distance, magnetic coupling between the low voltage input coil 2 and the high voltage output coil 3 is achieved. becomes worse, and the overall shape becomes larger. This type of coil device has an important use as an ignition coil for internal combustion engines with limited installation space, and miniaturization is an extremely urgent requirement. unable to respond adequately.

(b) Problems with the prior art shown in FIGS. 4 and 5: The shape of the bobbin 5 around which the high-voltage output coil 3 is wound becomes complicated, resulting in high costs. In particular, in the split winding bobbin 5, it is necessary to taper the bottom of each coil winding part 52 divided by the collar part 51.
The shape becomes more complex.

<Means for Solving the Problems> In order to solve the above-mentioned conventional problems, the present invention has a low voltage input coil and a coil disposed coaxially outside the low voltage input coil, with one end in the axial direction being the low voltage side. In a coil device comprising a high-voltage output coil wound such that the other end thereof is a high-voltage side, and a core disposed passing along the axes of both the coils, the core is arranged so that the axes of the two coils are A portion passing through the core has a cross-sectional shape that becomes narrower from the low-voltage side to the high-voltage side of the high-voltage output coil, and the low-voltage input coil is arranged along the outer periphery of the core.

<Function> The core has a cross-sectional shape in which a portion passing on the axes of the two coils becomes thinner from the low voltage side to the high voltage side of the high voltage output coil, and the low voltage input coil is arranged along the outer periphery of the core. Therefore, the insulation distance between the low voltage input coil and the high voltage output coil increases from the low voltage side to the high voltage side. The bobbin around which the high-voltage output coil is wound may have a straight shape without a tapered coil winding portion, and the bobbin structure is simpler than that of the prior art shown in FIGS. 4 and 5. Also, on the low voltage side, the insulation distance between the low voltage input coil and the high voltage output coil is shortened, so the third
Compared to the conventional technology shown in the figure, magnetic coupling is improved and the device is smaller.

The core has a tapered outer shape, but since the core can be made of a molded product such as ferrite, there is no difficulty in providing a taper.

<Example> FIG. 1 is a sectional view of a main part of a coil device according to the present invention. In the figures, the same reference numerals as in FIGS. 3 to 5 indicate the same components. The core 1 is made of, for example, ferrite, and has a cross-sectional shape in which a portion 101 passing over the axes of both the coils 2 and 3 becomes thinner from the low voltage side to the high voltage side of the high voltage output coil 3. A low voltage input coil 2 is arranged along the outer peripheral surface of this core 1. The low voltage input coil 2 is wound directly around the outer circumference of the core 1, or
Alternatively, a bobbin is attached to the core 2 and wound around this bobbin.

With the above structure, the lower voltage input coil 2 and the higher voltage output coil 3 increase from the low voltage side to the high voltage side.
The insulation distance between the The bobbin 5 on which the high-voltage output coil 3 is wound has a straight shape with no taper at the bottom of the coil winding section 52 defined by the collar section 51. Therefore,
The structure of the bobbin 5 is simpler than that of the prior art shown in FIGS. 4 and 5. Also, on the low voltage side, the insulation distance between the low voltage input coil 2 and the high voltage output coil 3 is shortened, so compared to the conventional technology shown in FIG.
Magnetic coupling is improved and the size is reduced.

FIG. 2 is a partial cross-sectional view of the coil device according to the present invention, which is embodied as an ignition coil, with an ignition plug attached. In the core 1, a rod-shaped portion 101 passing along the axes of both coils 2 and 3 has a cross-sectional shape that becomes thinner from the low voltage side to the high voltage side of the high voltage output coil 3, and this portion 101 is connected to the low voltage input coil 2. It is inserted into the inner diameter part 41 of the bobbin 4 wound with. A flange 102 is provided at the end of the portion 101, and the flange 102 compensates for the reduction in magnetic efficiency due to the open magnetic path, thereby improving the magnetic efficiency.

Further, a connector 6 whose connection direction coincides with the coil winding axis direction is attached to the axial end surface 54 of the bobbin 5 on the opposite side from the collar portion 102 by an appropriate means such as adhesive or screwing. 6 is connected to one end of the high voltage output coil 3. and,
Insulating cover 7 covers the outside of bobbin 5.
The spark plug 8 is inserted coaxially, and the end surface facing the connector 6 has an opening 71, and the spark plug 8 is inserted through the opening 71 and connected to the connector 6. In this way, since the spark plug 8 is directly inserted and connected to the connector 6 from the direction of the coil winding axis, the connection direction of the spark plug 8 substantially coincides with the coil winding axis direction of the coil device. As a result, the work of connecting the spark plug 8 is facilitated, and the overall shape of the spark plug 8 with the spark plug 8 attached is reduced in size and simplified, and the area required for attachment is reduced.

Furthermore, in this embodiment, iron, iron,
A shield case 9 made of a magnetic conductive material such as nickel or a non-magnetic conductive material such as copper and formed into a cylindrical shape with both ends open is inserted, and the electromagnetic waves generated from the connection between the spark plug 8 and the connector 6 are It is designed to prevent noise.

<Effects of the invention> As described above, the invention has a low-voltage input coil and a coil that is arranged coaxially outside the low-voltage input coil and is wound so that one end in the axial direction is the low voltage side and the other end is the high voltage side. In the coil device, the coil device includes a high-voltage output coil equipped with a high-voltage output coil, and a core disposed passing over the axes of both the coils, wherein a portion of the core passing over the axes of the two coils is connected to the high-voltage output coil. The cross-sectional shape becomes narrower from the low-voltage side to the high-voltage side, and the low-voltage input coil is arranged along the outer periphery of the core, so that the magnetic coupling between the low-voltage input coil and the high-voltage output coil is reduced. It is possible to provide a coil device that substantially increases the insulation distance without reducing the insulation distance, prevents dielectric breakdown between the coils, and achieves miniaturization.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main part of the coil device according to the present invention, Fig. 2 is a partial sectional view of the coil device according to the present invention embodied as an ignition coil with a spark plug attached, and Fig. 3 5 are sectional views of main parts of a conventional coil device. 1...Core, 2...Low voltage input coil, 3...High voltage output coil.

Claims (1)

[Scope of utility model registration request] A low-voltage input coil, a high-voltage output coil that is coaxially arranged outside the low-voltage input coil and wound so that one end in the axial direction is on the low-voltage side and the other end is on the high-voltage side, and In the coil device, a portion of the core that passes over the axes of the two coils has a cross-sectional shape that becomes thinner from the low voltage side to the high voltage side of the high voltage output coil, and the low voltage A coil device characterized in that an input coil is arranged along the outer periphery of the core.