JP6089780B2 - Ignition coil for internal combustion engines - Google Patents

Description

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

  As an ignition coil used for an internal combustion engine such as an engine, for example, a primary coil and a secondary coil arranged concentrically on the inner and outer circumferences, a central core arranged at an axial center position of the primary coil and the secondary coil, An outer peripheral core disposed so as to surround the outer sides of the primary coil and the secondary coil is provided. These components are housed in a case. A gap formed in the case is filled with a filling resin made of a thermosetting resin such as an epoxy resin.

  For example, Patent Literature 1 discloses an ignition coil including a bottomed cylindrical case that opens on one side in the axial direction of the central core and closes the other side. In manufacturing such an ignition coil, after placing components such as a primary coil, a secondary coil, a central core, and an outer core in the case, filling resin is poured into the case from the opening of the case. And cure.

JP 2011-187532 A

However, the ignition coil disclosed in Patent Document 1 has the following problems.
That is, in the vicinity of the opening of the case, a part of the outer peripheral core is disposed so as to cover one side of the central core in the axial direction, and in a state of covering the opening of the case. There is a portion where the ratio of the area occupied by the outer peripheral core to the opening cross-sectional area is large. Therefore, the flow of the filling resin filled in the case from the opening of the case is hindered by the outer core, and the filling operation takes time. Thereby, there exists a possibility that the filling property (casting property) in the case of filling resin may fall.

  Moreover, in order to ensure the insulation between the windings of the primary coil and the secondary coil, it is necessary to impregnate the gaps in the windings with an insulating filling resin. Therefore, the filling resin is filled in the case in a negative pressure state. However, the air replaced with the filling resin in the case such as the inside of the winding is difficult to escape from the case opening to the outside of the case by a part of the outer peripheral core disposed near the case opening. It becomes easy to stay in (especially inner side of an outer periphery core). As a result, voids (bubbles) are formed inside the filled resin, and cracks are generated starting from the voids, which may cause insulation failure.

  The present invention has been made in view of such a background, and provides an ignition coil for an internal combustion engine that can improve filling efficiency of a filled resin into a case, improve production efficiency, and is excellent in reliability. It is something to try.

One aspect of the present invention includes a primary coil and a secondary coil that are arranged concentrically on the inner and outer peripheries,
A central core disposed at the axial center position of the primary coil and the secondary coil;
An outer peripheral core disposed so as to surround the outside of the primary coil and the secondary coil;
A case for housing the primary and secondary coils, the central core, and the outer core;
A filling resin made of a thermosetting resin filled in the case,
The case has a bottomed cylindrical shape having an opening for filling the filling resin on one side in the axial direction of the central core and closing the other side in the axial direction.
The outer peripheral core has a pair of opposing portions disposed opposite to each other on both sides in the axial direction with the central core in between, and a pair of connecting portions that connect the pair of opposing portions,
Among the pair of opposing portions of the peripheral core, the open side facing portion in the opening side of the case, Oite in a direction perpendicular to both the arrangement direction of the axial direction and the pair of connecting portions That at least one of the recessed part recessed from the said connection part and the penetration part penetrated to the said axial direction is provided in the position shifted | deviated with respect to the said center core when it sees from the said axial direction. The ignition coil for an internal combustion engine is characterized.

  In the ignition coil, the case has a bottomed cylindrical shape having an opening on one side in the axial direction and closing the other side in the axial direction. The outer peripheral core has a pair of opposed portions disposed opposite to each other on both sides in the axial direction with the central core interposed therebetween. Of the pair of facing portions, the opening facing portion on the opening side of the case is provided with at least one of a recess and a penetrating portion.

  Therefore, the filling resin filled in the case in which components such as the outer peripheral core are arranged from the opening of the case is formed by the recesses and through portions of the opening-side facing portion of the outer core disposed near the opening of the case. That is, it easily flows into the entire case by passing through the concave portion or the through portion. Thereby, the filling property in the case of filling resin can be improved. In addition, production efficiency can be improved, such as shortening the filling operation time.

  On the other hand, the air replaced with the filling resin in the case, such as in the windings of the primary coil and the secondary coil, is caused by the recesses and through portions of the opening-side facing portion of the outer peripheral core disposed in the vicinity of the opening of the case. That is, by passing through the recessed portion or the penetrating portion, it is easy to come out of the case from the opening of the case. Thereby, it can prevent that a void (bubble) is formed in the inside of filling resin. And generation | occurrence | production of the crack which originates in a void and the insulation defect accompanying it can be prevented, and reliability can be improved.

  As described above, it is possible to improve the filling efficiency of the filling resin into the case, to improve the production efficiency, and to provide an ignition coil for an internal combustion engine having excellent reliability.

Sectional explanatory drawing which shows the ignition coil in Example 1. FIG. II-II arrow directional cross-sectional explanatory drawing of FIG. Explanatory drawing which looked at the outer periphery core in Example 1 from the opening part side of the case. FIG. 3 is an explanatory view showing an outer peripheral core in the first embodiment. Sectional explanatory drawing which shows the state which has arrange | positioned the ignition coil in the plug hole of an engine in Example 1. FIG. Explanatory drawing which shows the other example of an outer periphery core in Example 1. FIG. Explanatory drawing which shows the other example of an outer periphery core in Example 1. FIG. Sectional explanatory drawing which shows the ignition coil in Example 2. FIG. Explanatory drawing which looked at the outer periphery core in Example 2 from the opening part side of the case. Explanatory drawing which shows the other example of an outer periphery core in Example 2. FIG. Sectional explanatory drawing which shows the ignition coil in Example 3. FIG. In Example 3, (a) Explanatory drawing which looked at the outer periphery core from the opening part side of the case, (b) AA sectional view explanatory drawing of Fig.12 (a). Explanatory drawing which shows the outer periphery core in Example 3. FIG.

  In the ignition coil, at least one of the concave portion and the penetrating portion is provided in the opening-side facing portion of the outer peripheral core. That is, only one of the recessed portion and the penetrating portion may be provided on the opening-side facing portion of the outer peripheral core, or both may be provided.

Moreover, it is preferable to provide the said recessed part and the said penetration part in the position which does not affect a magnetic circuit as much as possible in the said opening side opposing part of the said outer periphery core.
Moreover, it is preferable to provide the said recessed part and the said penetration part so that the part in which the other components are assembled | attached in the said opening side opposing part of the said outer periphery core is avoided.

Further, the shape of the recess and the through portion is such that when the ignition coil is used in a high temperature environment, thermal stress generated between the outer core and the filling resin does not increase, and stress concentration does not occur. It is preferable to do so.
Moreover, the said recessed part and the said penetration part may be provided in both of a pair of said opposing part of the said outer periphery core, and you may make it the said outer periphery core become a shape which does not have assembly directionality. In this case, it becomes easy to place and assemble the outer core in the case.

In addition, the opening-side facing portion of the outer peripheral core is an inclined surface that is inclined outwardly toward the opening side of the case on the side opposite to the opening that is the end surface opposite to the opening side of the case. (Claim 2).
That is, the air substituted with the filling resin in the case, such as in the windings of the primary coil and the secondary coil, tends to stay on the end surface on the side opposite to the opening, particularly in the opening-side facing portion of the outer peripheral core. Therefore, by providing an inclined surface in such a place, the air replaced with the filling resin in the case can easily escape from the case opening to the outside of the case along the inclined surface. Thereby, it is possible to further prevent the formation of voids (bubbles) inside the filling resin.

Moreover, it is preferable that the said outer periphery core is a powder core formed by compression-molding magnetic material powder.
In this case, by adopting a compacted core having a high degree of freedom as the outer peripheral core, it is possible to easily produce an outer peripheral core having a complicated shape having a recess and a penetrating portion.

Example 1
Embodiments relating to the ignition coil will be described with reference to the drawings.
As shown in FIG. 1 to FIG. 4, the ignition coil 1 of this example includes a primary coil 21 and a secondary coil 22 that are concentrically arranged on the inner and outer circumferences, and an axial center of the primary coil 21 and the secondary coil 22. A central core 23 disposed at a position, an outer peripheral core 4 disposed so as to surround the primary coil 21 and the secondary coil 22, and the primary coil 21, the secondary coil 22, the central core 23, and the outer core 4. A case 3 to be accommodated and a filling resin 29 made of a thermosetting resin filled in the case 3 are provided.

As shown in the figure, the case 3 has a bottomed cylinder having an opening 31 for filling a filling resin 29 on one side in the axial direction X of the central core 23 and closing the other side in the axial direction X. It has a shape.
The outer peripheral core 4 includes a pair of facing portions 41 that are opposed to each other on both sides in the axial direction X with the central core 23 interposed therebetween, and a pair of connecting portions 42 that connect the pair of facing portions 41. Of the pair of facing portions 41 of the outer core 4, the opening facing portion 41 a on the opening 31 side of the case 3 is provided with a recess 51 that is recessed in a direction orthogonal to the axial direction X. Will be explained in detail.

  As shown in FIG. 1, the ignition coil 1 is configured by arranging components such as a primary coil 21, a secondary coil 22, a center core 23, and an outer core 4 in a case 3. FIG. 1 shows a state in which these components are assembled in the case 3 in a cross section viewed from the side.

  As shown in the figure, the primary coil 21 and the secondary coil 22 are concentrically arranged in the case 3 so as to overlap the inner and outer circumferences. The primary coil 21 is formed in a substantially cylindrical shape by winding a primary winding around the central core 23. The secondary coil 22 is formed by winding a secondary winding thinner than the primary winding on the secondary spool 25 made of an insulating resin arranged on the outer peripheral side of the primary coil 21 with a greater number of turns than the primary winding. It is formed in a cylindrical shape. The surfaces of the primary winding and the secondary winding are covered with an insulating film.

  As shown in the figure, the central core 23 is disposed on the inner peripheral side of the primary coil 21 and the secondary coil 22 and at the axial center positions of the primary coil 21 and the secondary coil 22. The central core 23 is formed in a substantially cylindrical shape so as to wind the primary winding constituting the primary coil 21. The central core 23 is constituted by a laminated core formed by laminating a number of electromagnetic steel plates made of a magnetic material. In addition, the center core 23 can also be comprised by the powder core formed by compression-molding magnetic material powder.

  As shown in FIG. 1 and FIG. 4, the outer core 4 constitutes a magnetic circuit together with the central core 23, and a pair of opposing portions disposed opposite to each other in the axial direction X with the central core 23 interposed therebetween. 41 and a pair of connecting portions 42 that connect the pair of opposed portions 41. The pair of connecting portions 42 are disposed to face each other in the radial direction of the central core 23 (the direction orthogonal to the axial direction X of the central core 23). And the outer periphery core 4 is formed in the cylinder shape so that the outer side of the primary coil 21 and the secondary coil 22 may be covered with a pair of opposing part 41 and a pair of connection part 42. FIG. Moreover, the outer periphery core 4 is comprised by the compacting core formed by compression-molding magnetic material powder.

  As shown in FIG. 1, the case 3 opens on one side in the axial direction X (hereinafter, appropriately referred to as one axial direction X1) and closes the other side (hereinafter, appropriately referred to as the other axial direction X2). It has a bottomed cylindrical shape. That is, the case 3 covers the outer peripheral side of the central core 23 and the other axial side X2 of the central core 23. An opening 31 for filling the filling resin 29 into the case 3 is provided on one side X1 in the axial direction of the case 3. Further, the case 3 is formed with a tower portion 32 for projecting a high voltage terminal 221 that is electrically connected to the high voltage side end of the secondary winding of the secondary coil 22.

  As shown in FIGS. 2 and 3, of the pair of facing portions 41 of the outer core 4, the opening facing portion 41 a on the opening 31 side of the case 3 is recessed in a direction orthogonal to the axial direction X. One recess 51 is provided. The recess 51 is formed by indenting an end surface 413 on the tower portion 32 side of the case 3 in the opening-side facing portion 41a. In FIG. 2, illustration of the filling resin 29 is omitted.

  As shown in FIGS. 1 and 2, an igniter 26 having a switching control circuit for energizing and interrupting the primary coil 21 is disposed near the opening 31 in the case 3. A connector portion 27 for connecting the conductive terminal 261 of the igniter 26 to an external device such as an ECU (Electronic Control Unit) is provided at a position adjacent to the igniter 26. The connector part 27 is formed so as to protrude from the opening 31 of the case 3. The conductive terminal 271 of the connector portion 27 is joined to the conductive terminal 261 of the igniter 26.

  As shown in FIG. 1, in a case 3 in which components such as a primary coil 21, a secondary coil 22, a center core 23, and an outer core 4 are accommodated, a filling resin 29 made of an epoxy resin, which is a thermosetting resin. Is filled. The filling resin 29 fixes these components in an insulated state in the case 3.

  As shown in FIG. 5, the ignition coil 1 having the above configuration is placed laterally outside the plug hole 83 of the engine (cylinder head 81 and cylinder head cover 82) as an internal combustion engine (centered with respect to the axial direction of the plug hole 83). The core 23 is disposed in a state in which the axial direction X of the core 23 is orthogonal. The ignition coil 1 is connected to a spark plug 7 disposed in the plug hole 83 via a rubber cylindrical plug cap 11.

  Specifically, the tower portion 32 of the case 3 is press-fitted into one side of the plug cap 11. In addition, a coil spring 12 that is electrically connected to the high voltage terminal 221 in the tower portion 32 of the case 3 is disposed inside the plug cap 11. Further, the insulator portion 71 of the spark plug 7 is press-fitted into the other side of the plug cap 11 so as to contact the coil spring 12.

Next, the effect of the ignition coil 1 of this example is demonstrated.
In the ignition coil 1 of this example, the case 3 has an opening 31 on one side in the axial direction X (one axial side X1) and closes the other side in the axial direction X (second axial side X2). It has a bottomed cylindrical shape. Further, the outer core 4 has a pair of facing portions 41 disposed facing each other on both sides in the axial direction X with the central core 23 interposed therebetween. And the recessed part 51 is provided in the opening side opposing part 41a in the opening part 31 side of the case 3 among a pair of opposing parts 41. As shown in FIG.

  Therefore, the filling resin 29 filled in the case 3 in which components such as the outer core 4 are arranged from the opening 31 of the case 3 is opposed to the opening side of the outer core 4 disposed in the vicinity of the opening 31 of the case 3. By passing through the recessed portion 51 by the recessed portion 51 of the portion 41a, it becomes easy to flow into the entire case 3. Thereby, the filling property in case 3 of filling resin 29 can be improved. In addition, production efficiency can be improved, such as shortening the filling operation time.

  On the other hand, the air replaced by the filling resin 29 in the case 3, such as in the windings of the primary coil 21 and the secondary coil 22, is the opening-side facing portion of the outer peripheral core 4 disposed in the vicinity of the opening 31 of the case 3. By passing through the recess 51 by the recess 51 of 41a, it becomes easy to come out of the case 3 from the opening 31 of the case 3. Thereby, it is possible to prevent the formation of voids (bubbles) inside the filling resin 29. And generation | occurrence | production of the crack which originates in a void and the insulation defect accompanying it can be prevented, and reliability can be improved.

  Moreover, in this example, the outer periphery core 4 is a powder core formed by compression-molding magnetic material powder. That is, by adopting a dust core having a high degree of freedom as the outer core 4, the outer core 4 having a complicated shape having the recess 51 can be easily manufactured.

  As described above, according to this example, it is possible to improve the filling property of the filling resin 29 into the case 3 to improve the production efficiency, and to provide the ignition coil 1 for an internal combustion engine having excellent reliability. Can do.

In this example, as shown in FIG. 3, one recess 51 is provided in the opening-side facing portion 41 a of the outer core 4. For example, as shown in FIG. 6, the opening-side facing portion 41 a of the outer core 4. A plurality of recesses 51 may be provided on the surface.
Moreover, in this example, as shown in FIG. 3, the recessed part 51 was provided in the end surface 413 by the side of the tower part 32 of the case 3 in the opening side opposing part 41a of the outer periphery core 4, For example, as shown in FIG. Furthermore, it is good also as a structure which provides the recessed part 51 in the end surface 414 on the opposite side to the tower part 32 of the case 3 in the opening side opposing part 41a of the outer periphery core 4. FIG.

  Moreover, in this example, as shown in FIGS. 1-4, although the recessed part 51 was provided in one opposing part 41 (opening side opposing part 41a) among a pair of opposing parts 41 of the outer periphery core 4, for example, You may make it the outer periphery core 4 become a shape which does not have assembly directionality, for example by providing the recessed part 51 in both of a pair of opposing parts 41. FIG. In this case, the outer core 4 can be easily placed and assembled in the case 3.

(Example 2)
In this example, as shown in FIGS. 8 and 9, the configuration of the outer core 4 is changed.
As shown in the figure, the opening side facing portion 41a of the outer peripheral core 4 is provided with two penetration portions 52 that penetrate in the axial direction X. One of the two penetrating parts 52 is formed on the end surface 413 side of the opening side facing part 41a, and the other is formed on the end surface 414 side of the opening side facing part 41a.
Other basic configurations are the same as those in the first embodiment. Moreover, about the structure similar to Example 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

The effect of this example will be described.
In this example, the filling resin 29 filled in the case 3 in which components such as the outer core 4 are arranged from the opening 31 of the case 3 is the opening of the outer core 4 disposed in the vicinity of the opening 31 of the case 3. By passing through the penetrating portion 52 of the side facing portion 41 a, that is, passing through the penetrating portion 52, it becomes easy to flow into the entire case 3. Thereby, the filling property in case 3 of filling resin 29 can be improved. In addition, production efficiency can be improved, such as shortening the filling operation time.

On the other hand, the air in the case 3 replaced with the filling resin 29 passes through the through portion 52 by the through portion 52 of the opening-side facing portion 41 a of the outer peripheral core 4 disposed in the vicinity of the opening portion 31 of the case 3. This facilitates removal from the opening 31 of the case 3 to the outside of the case 3. Thereby, it is possible to prevent the formation of voids (bubbles) inside the filling resin 29. And generation | occurrence | production of the crack which originates in a void and the insulation defect accompanying it can be prevented, and reliability can be improved.
Other basic functions and effects are the same as those of the first embodiment.

  In this example, as shown in FIG. 9, the opening-side facing portion 41 a of the outer core 4 is provided with a penetrating portion 52 instead of the concave portion 51 of the first embodiment.For example, as shown in FIG. 10, It is also possible to adopt a configuration in which both the concave portion 51 and the penetrating portion 52 are provided in the opening-side facing portion 41a of the outer peripheral core 4. In this case, the filling property of the filling resin 29 into the case 3 can be further improved, and the production efficiency can be further improved.

(Example 3)
In this example, as shown in FIGS. 11 to 13, the configuration of the outer peripheral core 4 is changed.
As shown in the figure, the opening-side facing portion 41a of the outer peripheral core 4 is directed to the non-opening-side end surface 412a, which is the end surface opposite to the opening 31 side of the case 3, toward the opening 31 side of the case 3. There is an inclined surface 49 that is inclined outward (to the end surface 413 side of the opening-side facing portion 41a). In FIG. 12B, only the opening side facing portion 41a is shown.
Other basic configurations are the same as those in the first embodiment. Moreover, about the structure similar to Example 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

Next, the function and effect of this example will be described.
In this example, the opening side facing portion 41a of the outer peripheral core 4 has an inclined surface 49 on the non-opening side end surface 412a. That is, the air replaced with the filling resin 29 in the case 3 such as in the windings of the primary coil 21 and the secondary coil 22 tends to stay on the non-opening side end face 412a in the opening side facing portion 41a of the outer peripheral core 4 in particular. Therefore, by providing the inclined surface 49 in such a place, the air replaced with the filling resin 29 in the case 3 can easily escape from the opening 31 of the case 3 to the outside of the case 3 along the inclined surface 49. Thereby, it is possible to further prevent the formation of voids (bubbles) inside the filling resin 29.
Other basic functions and effects are the same as those of the first embodiment.

DESCRIPTION OF SYMBOLS 1 Ignition coil 21 Primary coil 22 Secondary coil 23 Central core 29 Filling resin 3 Case 31 Opening part 4 Outer periphery core 41 Opposing part 41a Opening side opposing part 42 Connection part X Axial direction (axial direction of central core)

Claims (3)

A primary coil (21) and a secondary coil (22) arranged concentrically on the inner and outer circumferences;
A central core (23) disposed at an axial center position of the primary coil (21) and the secondary coil (22);
An outer peripheral core (4) disposed so as to surround the outside of the primary coil (21) and the secondary coil (22);
A case (3) for housing the primary coil (21) and the secondary coil (22), the central core (23), and the outer peripheral core (4);
A filling resin (29) made of a thermosetting resin filled in the case (3),
The case (3) has an opening (31) for filling the filling resin (29) on one side in the axial direction (X) of the central core (23) and the other in the axial direction (X). It has a bottomed cylindrical shape that closes the side,
The outer peripheral core (4) includes a pair of opposed portions (41) disposed opposite to each other on both sides in the axial direction (X) with the central core (23) interposed therebetween, and the pair of opposed portions (41). A pair of connecting portions (42) to be connected;
Of the pair of opposed portions (41) of the outer peripheral core (4), the opening-side facing portion (41a) on the opening (31) side of the case (3) has the axial direction (X) and the pair of connecting portions (42) Oite the connecting portion in a direction perpendicular to both (42) becomes recessed than the recess (51) and the penetrating section including through to the axial direction (X) between the alignment direction of the At least one of (52) is provided at a position shifted from the central core (23) when viewed from the axial direction (X). ).   The ignition coil (1) according to claim 1, wherein the opening-side facing portion (41a) of the outer peripheral core (4) is an end surface opposite to the opening (31) side of the case (3). An ignition coil (1) for an internal combustion engine having an inclined surface (49) inclined outward toward the opening (31) side of the case (3) on an end surface (412a) on the side opposite to the opening ).   The ignition coil (1) according to claim 1 or 2, wherein the outer core (4) is a dust core formed by compression-molding magnetic material powder. ).

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