JP2017011064A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil for an internal combustion engine which eliminates residual air in a resin fitting portion and prevents occurrence of cracks or generation of leakage current.SOLUTION: In a high pressure side case 120, a tubular body 121, a flange portion, flat portions 124 and 126 are integrally formed, and a large concave body 122 is formed at a central portion of the flat portion 124. The concave body 122 has a surrounding groove 127 around its periphery, the secondary coil is accommodated, and the protruding wall 134 and the groove 127 are fitted along the circumference. In the groove 127 of the high pressure side case 120, the inner groove wall is provided in the inner space D of the high pressure side case 120, and the outer dike wall is provided in the space facing the inner groove D, thereby forming the groove profile of the inner groove wall. A contact surface with the flange portion 133 is provided inside the external bank wall, whereby the insertion depth of the protruding wall 134 is limited, and a resin filling space is formed in the surrounding groove 127.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an ignition coil for an internal combustion engine, and more particularly to an insulation structure of an ignition coil for an internal combustion engine.

  In recent years, an internal combustion engine used for an automobile or the like employs a direct ignition system in which an ignition coil is provided in each plug hole. Such an ignition coil is composed of a transformer circuit section that boosts an input voltage and a high-voltage tower section that relays a high voltage from this circuit to a spark plug, and has a stick-like form as a whole. The high-pressure tower is inserted into the plug hole, and the entire ignition coil is mounted on the engine.

  For example, in the technique according to Patent Document 1, a high-pressure part impregnated body (high-pressure side insulating structure) that covers the periphery of the secondary coil, and a non-high-pressure part impregnated body (outer peripheral insulating structure) that covers the periphery of the high-pressure part impregnated body. Thus, an insulating structure around the transformer circuit is formed. In such an insulating structure, first, a first case body in which a secondary coil is accommodated is formed, and an epoxy resin is impregnated and thermally cured in the space to form a high-pressure portion impregnated body. After that, the remaining transformer circuit is mounted around the high-pressure part impregnated body, a second case body is formed so as to surround it, and the space is impregnated with epoxy resin and thermally cured to impregnate the non-high-pressure part. The body is formed.

JP 2014-207289 A

  According to Patent Document 1, when forming the secondary coil housing space, the first case body is divided into a divided structure and assembled. For this reason, in order to assemble the first case body using the divided parts, it is necessary to fit the edges of both parts. However, when manufactured in this way, a space in which air remains is left at the fitting position of both parts (parts of the first case body), which causes cracks. In particular, since the first case is a structure that accommodates the secondary coil, the cause of the resin crack must be eliminated as much as possible.

  On the edge of the first case, if air remains in the fitting portion, electrolytic concentration occurs here, leading to an electrical leakage phenomenon. In such an ignition coil, when a secondary coil is disposed in the immediate inner periphery of the first case, it is difficult to provide a sufficient output voltage to the ignition plug when a leak phenomenon occurs.

  In view of the above problems, an object of the present invention is to provide an ignition coil for an internal combustion engine that can eliminate residual air in a resin fitting portion and prevent generation of cracks or leakage current.

In order to solve the above problems, the present invention has the following configuration of an ignition coil for an internal combustion engine. That is, a first assembly structure, a second assembly structure that is assembled to the first assembly structure to form an internal space, a coil component that is accommodated in the internal space, A filling resin filled in the internal space,
The fitting portion where the first assembly structure and the second assembly structure are fitted to each other is provided with a filling space for the filling resin.

  Preferably, the second assembly structure is provided with a flange portion in the vicinity of an end portion forming the fitting portion.

  Preferably, the flange portion is provided with a convex portion between itself and the first assembly structure, and a gap portion is provided around the convex portion.

  Preferably, the gap portion is filled with the filling resin.

  According to the ignition coil for an internal combustion engine according to the present invention, since the resin is filled in the gap between the resin fitting portions, the structure around the resin fitting portion is homogenized, and the occurrence of cracks caused by this is suppressed. Further, since the residual air is excluded in the resin fitting portion, it is possible to prevent the occurrence of a leak current flowing therethrough.

The figure which shows the structure of the ignition coil for internal combustion engines which concerns on embodiment. The figure which shows the structure of the 1st case which concerns on embodiment. The figure (the 1) which shows the fitting part of the 1st case which concerns on embodiment. The figure which shows the fitting part of the 1st case which concerns on embodiment (the 2).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the configuration of an internal combustion engine ignition coil according to the present embodiment. As shown in FIG. 1A, an internal combustion engine ignition coil 100 (hereinafter referred to as an ignition coil 100) is assembled with an outer case 110 and a high-pressure side case 120 to form a space for accommodating coil components. The In the present embodiment, the assembling part is provided on the outer edge part, and this appears in a part that can be observed from the outside.

  The outer case 110 includes a cylindrical side surface portion 111, a top surface portion 112 that closes one end of the side portion, a flange portion 113 in which a metal bush is provided, a connector portion 114 in which a terminal group 114a is provided, and the like. Is formed. The structure of the outer case 110 is formed by molding a thermoplastic resin such as PBT or PPS, and the above-described shape configuration is appropriately formed.

  As shown in FIG. 1B, the ignition coil 100 is provided with a high-pressure resin structure. As shown in FIG. 2, the case structure of the high-pressure side resin structure is obtained by assembling the inner case 130 (first assembly structure) and the high-pressure side case 120 (second assembly structure). Become. In such a case structure, the end of the secondary spool 103 is fitted into the case opening 132, and the outer surface of the secondary spool 103 and the inner surface of the case structure (that is, the inner surface of the inner case 130 and the inner surface of the flange 123). The internal space D is formed in a substantially rectangular tube shape. That is, among the coil components, the secondary coil belongs to the “coil component housed in the internal space”.

  In such a case structure, the opening end of the internal space D is provided on the left side of the drawing (see FIG. 1B). From here, an epoxy resin (filling resin) is charged and thermally cured, so that an insulating property is obtained. A high-pressure resin structure is formed. Incidentally, the secondary spool 102 is appropriately wound around the secondary spool 103, and the secondary winding 102 is solidified while being kept in an insulating state by an epoxy resin.

  As shown in FIG. 1B, coil parts such as a primary coil 160 and an iron core 180 (a combination of an I-shaped iron core and an exterior iron core) are arranged around the high-voltage side case 130. Further, an igniter 130 connected to a connector terminal 114a and a coil winding is provided at one end of the iron core 180. And the outer case 110 is assembled | attached to the high voltage | pressure side case 120 so that these components group may be accommodated in the inside, The clearance gap in the inside is hardened with an epoxy resin etc., and the insulation structure in that is formed ( The resin filling is performed through the opening Y).

  The high-pressure side case 120 includes a cylindrical body 121 fitted to the plug boot, a conical flange 123 extending radially from the outer peripheral surface of the cylindrical body 121, and a part having a flat shape at its end. The mounting parts 124 and 126 are integrally formed. The material of the case structure is not particularly limited as long as it has a function similar to that of the external case 110 described above.

  As shown in the drawing, the high-voltage side case 120 is provided with a relay terminal 141 electrically connected to the output end of the secondary coil 122 and a high-voltage terminal 142 electrically connected thereto. The high-voltage terminal 142 is disposed such that one end thereof faces the communication hole of the cylindrical body 121 and is electrically connected to the spark plug via a relay conductor (not shown).

  In the ignition coil 100 configured as described above, when a drive signal is input to the connector terminal 114a, the power transistor built in the igniter 130 is driven, and the energization / cutoff state of the primary coil is controlled according to the combustion timing. The And at the time of interruption | blocking operation | movement of a primary current, the magnetic flux of an iron core changes rapidly and an excitation voltage is produced | generated by the secondary coil 122. FIG. Therefore, in the spark plug in the engine, an excitation voltage is applied to the plug gap to generate a spark.

  The case structure on the high pressure side will be described in detail below with reference to FIGS. As shown in FIG. 2A, the inner case 130 is composed of a substantially shell-like body 131 formed of an insulating material. A large opening is formed on each of the bottom surface and the facing surface of the case opening 132 in the shell-like body, and these shells communicate with each other at adjacent portions. As described above, a substantially square case opening 132 is formed in the shell 131. On the bottom surface of the inner case 130, a flange 133 and a protruding wall 134 are integrally formed so as to follow the edge of the shell 131. The height of the protruding wall 134 is set so that it can be inserted to an appropriate depth with respect to the predetermined groove. On the other hand, the flange 133 is processed into a shape that prevents movement in the insertion direction (for example, a shape that is substantially perpendicular) so that the protruding wall 134 does not fit too much into the predetermined groove.

  As described above, in the high-pressure side case 120, the cylindrical body 121, the flange portion 123, and the flat portions 124 and 126 are integrally formed, and a large concave body 122 is formed at the central portion of the flat portion 124. The concave body 122 is provided with a rotary moat 127 around it, and a part of the secondary coil is accommodated, and at the same time, the protruding wall 134 and the rotary moat 127 are fitted along the circumference. That is, the location A where the protruding wall 134 and the rotary moat 127 are fitted to each other (hereinafter referred to as the fitting portion A) refers to one form of the fitting portion in the claims. The meaning of the term “joint” is not limited to this.

  FIG. 3 illustrates variations of the above-described fitting portion. The upper part of the drawing shows the state of the fitting part observed in the axial direction of the plug hole, and the lower part of the drawing shows here. The state which observed the AA cross section shown toward the arrow line direction is shown. As shown in FIG. 3A, an internal dam wall 124a is provided in the internal space D, and an external dam wall 124b is provided in a space (external space) opposite to the internal groove D, as shown in FIG. Thereby, the outline of the rotation groove 127 is formed. Further, in the present embodiment, a contact surface with the flange portion 133 is provided inside the external dam wall 124b, whereby the insertion depth of the projecting wall 134 is limited, and resin in the circumferential groove 127 is formed. A filling space X is formed.

  In the present embodiment, the filling space X is formed by abutting the flange portion 133 provided in the vicinity of the end portion of the inner case. However, the present invention is not limited to this. It is possible to form a similar filling space X using an attachment jig or the like. In addition, this flange part 133 is provided in the edge part vicinity of the inner case 130 so that the filling space X can be formed easily. A communication path (not shown) is formed in the filling space X. When a liquid epoxy resin is introduced into the internal space D, the filling space X is also filled with the epoxy resin through the communication path. Thereafter, when the structure is subjected to a thermosetting process, the filling space X is cured in a state where the epoxy resin is filled without a gap.

  As described above, according to the ignition coil 100 according to the present embodiment, the gap X between the resin fitting portions is filled with epoxy resin, so that the structure around the resin fitting portion is homogenized so as not to be accompanied by an air layer. The For this reason, in the fitting part A, the cause of stress concentration is eliminated, and the occurrence of cracks caused by this is suppressed. Further, since the residual air is excluded in the resin fitting portion, it is possible to prevent the occurrence of a leak current flowing therethrough.

  FIG. 3B shows an example of the resin communication path described above. According to the figure, an appropriate slit 124 c is formed in the inner dam wall 124 a at a portion in contact with the inner wall of the inner case 130. Therefore, the internal space D in the case communicates with the filling space X through the slit 124c. For this reason, the slit 124c is appropriately devised so as not to increase the frictional resistance with respect to the liquid epoxy resin. For example, the direction of the slit 124c is preferably matched with the insertion direction into the circumferential groove so that a sufficient gradient can be secured. Also, the width, diameter, and construction location of the slit 124c are preferably set to a sufficiently large size and an appropriate number so as to reduce frictional resistance. In addition, as shown in FIG. 3C, a weir 124d may be provided at the top of the internal bank wall 124a to restrict the resin flow rate to the filling space X. According to this, since the rising speed of the liquid level in the filling space X is lowered, such a structure makes it difficult for the remaining bubbles to remain here, and the generation of cracks can be further suppressed.

  In the embodiment shown in FIG. 4, an appropriate convex portion 135 is formed on the contact surface of the flange portion 133. The convex portion 135 is sufficiently small in width and height so that it can be accommodated in a space formed in the vicinity of the contact surface of the flange portion 133. Therefore, when the high-pressure side case 120 and the inner case 130 are combined, the convex portion 135 is arranged in the contact direction of the flange portion 133 in the vicinity of the fitting portion, and a gap is formed around the convex portion 135. Then, by filling the area with an epoxy resin or the like, the bonding force in the vicinity of the fitting portion is further enhanced. In addition, as shown in FIG. 2A, it is more preferable to provide a plurality of such convex portions 135 at a predetermined pitch.

  Although not drawn on the drawing of FIG. 4, the filling resin is guided to the second space Z (gap portion) in which the convex portion 135 is accommodated by providing an appropriate communication path. . The communication path may be, for example, a groove communicating with the filling space X, or may be one communicating with the external space side where the epoxy resin is filled later.

  100 ignition coil for internal combustion engine, 110 outer case, 120 high pressure side case (second assembly structure), 130 inner case (first assembly structure), 170 coil component housed in internal space, A fitting Joint, D interior space, X filling space.

Claims (4)

A first assembly structure, a second assembly structure that is assembled to the first assembly structure to form an internal space, a coil component that is accommodated in the internal space, and the internal space Filling resin filled in,
An ignition coil for an internal combustion engine, wherein a fitting space in which the first assembly structure and the second assembly structure are fitted to each other is provided with a filling space for the filling resin.   The ignition coil for an internal combustion engine according to claim 1, wherein the second assembly structure is provided with a flange portion in the vicinity of an end portion that forms the fitting portion.   The internal combustion engine according to claim 2, wherein the flange portion is provided with a convex portion between itself and the first assembly structure, and a gap portion is provided around the convex portion. Ignition coil.   4. The internal combustion engine ignition coil according to claim 3, wherein the gap portion is filled with the filling resin.

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