JP2016051788A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil for internal combustion engine capable of positioning an ignitor extremely simply, while down-sizing the ignition coil.SOLUTION: An ignition coil for internal combustion engine includes a primary coil 21 wound on the outer periphery of a primary spool 3, a secondary coil 22 wound on the outer periphery of a secondary spool 4, a center core 5, an outer peripheral core 6, an ignitor 7, a case 11 and a filling resin 13. In the secondary spool 4, a plurality of flanges 42A, 42B for winding the secondary coil 22 while partitioning into a plurality are formed side by side in the central axis direction C of the secondary spool 4. At the end on the opening 111 side of the case 11 in the plurality of flanges 42A, 42B, a positioning part 43 for positioning the ignitor 7 is provided oppositely thereto.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an internal combustion engine ignition coil for generating a spark for ignition in a spark plug.

  The ignition coil is formed by arranging an assembly in which a primary coil, a secondary coil, a central core and an outer peripheral core are assembled in a case, and filling a gap in the case with a filling resin. In addition, the shape of the ignition coil differs depending on whether the assembly is disposed outside the plug hole or inside the plug hole. The structure in which the assembly is arranged outside the plug hole is advantageous in that the ignition performance can be designed without the physique of the ignition coil being influenced by the inner diameter of the plug hole.

  For example, Patent Document 1 discloses an internal combustion engine ignition coil in which a primary coil, a secondary coil, a laminated iron core, an igniter, and the like are arranged in an insulating case, and a gap in the insulating case is filled with an insulating resin. . In this ignition coil, an igniter accommodating portion for accommodating an igniter is provided at a position facing the secondary coil. Then, by making the height dimension of the side wall of the igniter housing part higher than the height dimension of the igniter itself, the progress of cracks generated from the edge of the igniter is stopped.

Japanese Patent Laid-Open No. 2008-130885

  However, in patent document 1, it is necessary to provide an igniter accommodating part in an insulation case separately, and the structure of an insulation case becomes complicated. Moreover, in patent document 1, the positioning fixing method of an igniter accommodating part is not disclosed. Furthermore, a space filled with an insulating resin is formed between the igniter housing and the secondary coil, and this space hinders the size reduction of the ignition coil.

  The present invention has been made in view of such a background, and has been obtained in order to provide an ignition coil for an internal combustion engine in which the igniter can be positioned extremely easily and the ignition coil can be reduced in size.

One aspect of the present invention is a primary coil;
A secondary coil wound around the outer periphery of the secondary spool and concentrically disposed on the outer periphery of the primary coil;
A central core disposed on the inner periphery of the primary coil;
An annular outer core surrounding the secondary coil;
An igniter having a built-in switching element for energizing and interrupting the primary coil;
A case for accommodating the primary coil, the secondary coil, the central core, the outer peripheral core and the igniter from an opening;
A filling resin filling the gap in the case,
In the secondary spool, a plurality of flanges for partitioning and winding the secondary coil into a plurality are formed side by side in the central axis direction of the secondary spool,
An ignition for an internal combustion engine, characterized in that a positioning portion for positioning the igniter is provided at an end of the case on the opening side of the plurality of flanges so as to face the igniter. In the coil.

In the internal combustion engine ignition coil, the igniter is positioned by using a secondary spool. Specifically, a positioning portion is provided at the end portion of the case on the opening side of the plurality of flanges of the secondary spool, and the igniter is positioned in at least one direction by the positioning portion. Accordingly, the secondary spool can be used for positioning the igniter, and the structure for positioning the igniter can be greatly simplified.
Even if the igniter is arranged on the opening side of the case with respect to the secondary coil and the secondary spool, the space between the igniter and the secondary coil can be made as small as possible. In addition, the space between the secondary coil and the igniter can be ensured with high accuracy. Therefore, it can prevent that an ignition coil will become large in the opening part side of a case.

  Therefore, according to the ignition coil for an internal combustion engine, the igniter can be positioned extremely easily and the ignition coil can be downsized.

Cross-sectional explanatory drawing which shows the ignition coil concerning an Example. Plane explanatory drawing which shows the ignition coil concerning an Example. Cross-sectional explanatory drawing which expands and shows the periphery of the igniter in FIG. Sectional explanatory drawing which shows the formation state of the collar part and positioning part in a secondary spool concerning an Example in the state seen from the center axis line direction of the secondary spool. FIG. 5 is an explanatory cross-sectional view showing a case where a guide portion is formed on the secondary spool in FIG. 4. FIG. 4 is an explanatory plan view showing a case where the direction in which the igniter is arranged on the secondary spool is 90 ° different from that in FIG. 2 according to the embodiment.

A preferred embodiment of the above-described ignition coil for an internal combustion engine will be described.
In the internal combustion engine ignition coil, the positioning portion is provided at a plurality of center side flanges facing the igniter, located in a central portion of the plurality of flanges in the central axis direction. The height of the outer brim other than the central brim that faces the vicinity of both corners of the igniter can be made lower than the height of the central brim.
Further, the height of the outer portion of the secondary coil facing the vicinity of both corners of the igniter can be made lower than the height of the center side portion of the secondary coil.

  In the cooling process of the heating / cooling cycle of the internal combustion engine, when the ignition coil is thermally contracted, a high thermal stress is generated in the filled resin due to a difference in thermal expansion coefficient between the filled resin and the igniter. Further, high thermal stress is also generated in the filling resin by restraining the thermal contraction of the filling resin and the igniter in the direction of the central axis of the secondary coil by the central core. When the filling resin cannot withstand the repeatedly generated thermal stress, cracks may occur in the portion of the filling resin that faces both corners of the igniter in the central axis direction of the secondary coil. Cracks that occur in the filling resin due to differences in the dimensional ratios of the components that make up the ignition coil and the thermal expansion coefficient depending on the materials used, etc., are secondary from the corners of the igniter that are located on the opposite side of the case opening In many cases, it progresses inclined toward the coil side. When this crack reaches the secondary coil, there is a risk of causing problems such as disconnection of the secondary coil.

Therefore, the height of the outer collar portion of the secondary spool is lowered so as to be away from the igniter, or the height of the outer portion of the secondary coil is lowered so as to be separated from the igniter. It is possible to prevent a crack generated in the portion of the filling resin facing the corner from reaching the secondary coil.
In addition, the outer diameter of the outer part can be reduced so that the outer part of the secondary coil is separated from the igniter by disposing most of the secondary coil at a position facing the igniter body. It is possible to avoid a crack generated in the filling resin from the corners of both ends of the igniter reaching the secondary coil.

Below, the Example concerning the ignition coil 1 for internal combustion engines is described with reference to drawings.
As shown in FIGS. 1 and 2, the internal combustion engine ignition coil 1 (hereinafter simply referred to as the ignition coil 1) includes a primary coil 21, a secondary coil 22, a central core 5, an outer peripheral core 6, an igniter 7, and a case 11. And a filling resin 13. The primary coil 21 is wound around the outer periphery of the primary spool 3. The secondary coil 22 is wound around the outer periphery of the secondary spool 4 and is arranged concentrically on the outer periphery of the primary coil 21. The central core 5 is disposed on the inner periphery of the primary coil 21. The outer peripheral core 6 is formed in an annular shape surrounding the secondary coil 22. The igniter 7 has a built-in switching element 711 for energizing and interrupting the primary coil 21. The case 11 is configured to accommodate the primary coil 21, the secondary coil 22, the central core 5, the outer peripheral core 6, and the igniter 7 from the opening 111. The filling resin 13 has an insulating property and fills the gap in the case 11.
As shown in FIGS. 3 and 4, the secondary spool 4 has a plurality of flange portions 42 </ b> A and 42 </ b> B for partitioning and winding the secondary coil 22 in a plurality in the central axis direction C of the secondary spool 4. It is formed side by side. A positioning portion 43 for positioning the igniter 7 is provided at the end of the plurality of flange portions 42A and 42B on the opening 111 side of the case 11 so as to face the igniter 7.

Hereinafter, the ignition coil 1 of this example will be described in detail with reference to FIGS.
The ignition coil 1 is disposed in each cylinder of the engine, and generates a spark voltage for generating a spark from the spark plug disposed in the plug hole of each cylinder.
In the ignition coil 1 of this example, the primary coil 21, the secondary coil 22, the central core 5 and the outer core 6 are arranged outside the plug hole, and the joint portion 12 connected to the ignition plug is arranged in the plug hole. Is.

  As shown in FIG. 1, the central core 5 is formed in a rectangular parallelepiped. The primary coil 21 is wound around the outer periphery of the primary spool 3 having a substantially square cylindrical cross section with rounded corners. The secondary coil 22 is wound around the outer periphery of the secondary spool 4 having a substantially square cylindrical cross section with rounded corners. The outer peripheral core 6 is formed in a substantially square ring shape whose outer corners are rounded. The center core 5 and the outer core 6 are formed of soft magnetic electromagnetic steel plates laminated in the penetration direction L of the outer core 6. The outer core 6 is provided with a resin core cover 61 facing the inner surface of the outer core 6, one end surface in the penetrating direction L, and the other end surface. The penetration direction L of the outer core 6 is directed to the direction of the opening 111 of the case 11, and the case 11 is formed in a substantially square vessel shape along the shape of the outer core 6 having a substantially square ring shape. The case 11 has an opening 111 on the side opposite to the side where the joint portion 12 is formed in the ignition coil 1.

As shown in FIG. 3, the primary spool 3 includes a cylindrical tube portion 31 around which the primary coil 21 is wound, and a connector portion 32 connected to an end portion of the tube portion 31. A part of the connector portion 32 of the primary spool 3 is fitted into a notch formed in the case 11 to constitute a part of the case 11.
The filling resin 13 is a thermosetting resin such as an epoxy resin, and insulates and fixes the primary coil 21 and the secondary coil 22 in the case 11.

  As shown in FIG. 3, the plurality of flange portions 42 </ b> A and 42 </ b> B of the secondary spool 4 are formed so as to protrude radially outward from the outer periphery of the cylindrical tube portion 41 around which the secondary coil 22 is wound. . The plurality of flange portions 42 </ b> A and 42 </ b> B are formed side by side in the central axis direction C of the secondary spool 4 according to the interval separating the secondary coil 22. The plurality of flange portions 42 </ b> A and 42 </ b> B are formed in an annular shape along a direction orthogonal to the central axis direction C of the secondary spool 4. The plurality of flanges 42A and 42B are located in the center portion of the secondary spool 4 in the central axial direction C, and face the central side flanges 42A facing the igniter 7 and the vicinity of both end corners 701 of the igniter 7. It is comprised by the outer side collar part 42B to do. The height of the outer flange 42B is lower than the height of the center flange 42A.

Further, the height of the outer portion 221B of the secondary coil 22 wound adjacent to the outer flange portion 42B is the center side portion of the secondary coil 22 wound adjacent to the central flange portion 42A. It is lower than the height of 221A. Further, most of the secondary coil 22 wound around the secondary spool 4 is disposed at a position facing the igniter 7.
As shown in FIG. 4, the positioning portion 43 of this example is provided so as to increase the protruding amount of the plurality of center side collar portions 42A. Further, the positioning portion 43 is integrally formed with the center side flange portion 42A.

  As shown in FIG. 3, when the filling resin 13 undergoes thermal contraction in the cooling process of the heating / cooling cycle of the internal combustion engine, the filling resin 13 has a larger thermal expansion coefficient than the igniter 7, and thus the filling resin 13. High thermal stress is generated. Further, the thermal stress of the filling resin 13 and the igniter 7 in the central axis direction C of the secondary coil 22 is also restrained by the central core 5, so that a high thermal stress is generated in the filling resin 13. Further, this thermal stress is concentrated in the corner portions 701 located on the opposite side to the opening 111 side of the case 11 in the igniter 7 having a thermal expansion coefficient smaller than that of the filling resin 13.

  When the filling resin 13 cannot withstand repeated thermal stress, a crack K occurs in the portion of the filling resin 13 facing the both end corners 701 of the igniter 7 in the central axis direction C of the secondary coil 22. There is a fear. Further, the crack K generated in the filling resin 13 is located on the opposite side of the igniter 7 from the opening 111 of the case 11 due to the difference in the thermal expansion coefficient depending on the dimensional ratio of each member constituting the ignition coil 1 and the material used. In many cases, it advances from the both end corner portions 701 to the secondary coil 22 side with an inclination of about 45 degrees. When the crack K reaches the secondary coil 22, there is a risk of causing problems such as disconnection of the secondary coil 22.

  Therefore, in the ignition coil 1, most of the secondary coil 22 wound around the secondary spool 4 is disposed at a position facing the igniter 7, and the height of the outer flange 42 </ b> B in the secondary spool 4 is from the igniter 7. It ’s low enough to leave. Further, the height of the outer portion 221 </ b> B of the secondary coil 22 is lowered so as to be separated from the igniter 7. As a result, even if the crack K generated in the portion of the filling resin 13 facing the both corners 701 of the igniter 7 progresses due to the thermal contraction of the filling resin 13, it reaches the secondary coil 22. Can be prevented.

As shown in the figure, the igniter 7 includes a substrate 71 provided with a switching element 711, a heat radiating plate 72 for releasing heat generated in the substrate 71, and a mold resin 73 covering the heat radiating plate 72 and the substrate 71. Have. The igniter 7 is formed in a flat plate shape that includes the substrate 71 and the heat radiating plate 72, and is arranged so that the flat plate surface faces the center side flange 42 </ b> A of the secondary spool 4. The heat sink 72 is disposed on the opening 111 side of the case 11 with respect to the substrate 71. Thereby, the heat generated from the switching element 711 is easily radiated from the surface of the filling resin 13 located on the opening 111 side of the case 11 by the heat radiating plate 72.
A terminal 74 connected to the switching element 711 and the like is drawn out from the end surface of the igniter 7 in the central axis direction C. The terminal 74 is connected to an external connection terminal 321 disposed on the connector portion 32 of the primary spool 3. The connector portion 32 of the primary spool 3 is arranged in a direction parallel to the central axis direction C of the secondary spool 4.

As shown in FIG. 5, the guide part 44 that guides the igniter 7 placed on the positioning part 43 can be provided on the center side collar part 42 </ b> A from both sides in the direction orthogonal to the center axis direction C. The guide portion 44 can be divided and provided in each of the plurality of center side collar portions 42A.
In addition, as shown in FIG. 6, the igniter 7 has a positioning portion for the center side collar portion 42 </ b> A of the secondary spool 4 in a state in which the terminal 74 is pulled out from the end surface in the direction orthogonal to the central axis direction C of the secondary spool 4. 43 can also be arranged.

In the ignition coil 1 of this example, the igniter 7 is positioned using the secondary spool 4. Specifically, a positioning portion 43 is provided at an end portion of the case 11 on the opening 111 side in the plurality of flange portions 42A and 42B of the secondary spool 4, and the igniter 7 is positioned by the positioning portion 43. Is called. As a result, the secondary spool 4 can be used for positioning the igniter 7, and the structure for positioning the igniter 7 can be greatly simplified.
Further, since the positioning portion 43 is provided integrally with the secondary spool 4, the positional relationship between the igniter 7, the secondary coil 22, and the secondary spool 4 can be determined with high accuracy.

Even if the igniter 7 is arranged on the side of the opening 111 of the case 11 with respect to the secondary coil 22 and the secondary spool 4, the space between the igniter 7 and the secondary coil 22 can be made as small as possible. it can. Therefore, the ignition coil 1 can be prevented from becoming large toward the opening 111 side of the case 11.
Therefore, according to the ignition coil 1 of the present example, the igniter 7 can be positioned extremely easily, and the ignition coil 1 can be downsized.

DESCRIPTION OF SYMBOLS 1 Ignition coil 11 Case 111 Opening part 13 Filling resin 21 Primary coil 22 Secondary coil 3 Primary spool 4 Secondary spool 42A, 43B collar part 43 Positioning part 5 Center core 6 Outer core 7 Igniter

Claims (5)

A primary coil (21);
A secondary coil (22) wound around the outer periphery of the secondary spool (4) and arranged concentrically on the outer periphery of the primary coil (21);
A central core (5) disposed on the inner periphery of the primary coil (21);
An annular outer core (6) surrounding the secondary coil (22);
An igniter (7) having a built-in switching element (711) for energizing and interrupting the primary coil (21);
A case (11) for accommodating the primary coil (21), the secondary coil (22), the central core (5), the outer peripheral core (6) and the igniter (7) from an opening (111);
Filling resin (13) filling the gap in the case (11),
The secondary spool (4) has a plurality of flanges (42A, 42B) for partitioning and winding the secondary coil (22) in a plurality in the direction of the central axis of the secondary spool (4) ( C) are formed side by side,
Positioning for positioning the igniter (7) at the end on the opening (111) side of the case (11) in the plurality of flanges (42A) so as to face the igniter (7) An ignition coil (1) for an internal combustion engine, characterized in that a portion (43) is provided. The positioning portion (43) is located at a central portion in the central axis direction (C) of the plurality of flange portions (42A, 42B), and a plurality of center side flange portions facing the igniter (7). (42A),
The height of the outer flange portion (42B) other than the central flange portion (42A) opposed to the vicinity of both corners (701) of the igniter (7) is higher than the height of the central flange portion (42A). 2. The ignition coil (1) for an internal combustion engine according to claim 1, characterized in that it is low. The positioning portion (43) is located at a central portion in the central axis direction (C) of the plurality of flange portions (42A, 42B), and a plurality of center side flange portions facing the igniter (7). (42A),
The height of the outer portion (221B) of the secondary coil (22) facing the vicinity of both corners (701) of the igniter (7) is the center side portion (221A) of the secondary coil (22). The ignition coil (1) for an internal combustion engine according to claim 1, characterized in that it is lower than the height.   A guide portion (44) for guiding the igniter (7) mounted on the positioning portion (43) from both sides in a direction orthogonal to the central axis direction (C) is provided on the center side collar portion (42A). The ignition coil (1) for an internal combustion engine according to any one of claims 1 to 3, wherein is provided. The igniter (7) includes a substrate (71) provided with the switching element (711), a heat radiating plate (72) for releasing heat generated in the substrate (71), the heat radiating plate (72), A mold resin (73) covering the substrate (71),
The said heat sink (72) is arrange | positioned with respect to the said board | substrate (71) at the opening part (111) side of the said case (11), The Claim 1 characterized by the above-mentioned. An internal combustion engine ignition coil (1).

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