JP2015156447A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil for an internal combustion engine which secures insulation resistance of a protector part and fitting strength between a pole joint and a plug cap.

SOLUTION: An ignition coil 1 for an internal combustion engine includes: a coil body part 2; and a protector part 4 holding a conduction member 3 therein. The protector part 4 includes: a cylindrical pole joint 41; and a plug cap 42 which is fitted into a joint tip part 411 forming an end part of the pole joint 41 which is located at the opposite side of the coil body part, the plug cap 42 connecting a spark plug. The pole joint 41 has a flange part 412 which protrudes to the outer periphery side at the base end side of the joint tip part 411. The plug cap 42 is fitted in the joint tip part 411 from the outer periphery side contacting with the flange part 412.

COPYRIGHT: (C)2015,JPO&INPIT

Description

  The present invention relates to an ignition coil for an internal combustion engine for igniting by applying a high voltage to a spark plug disposed in the internal combustion engine.

2. Description of the Related Art Some ignition coils for internal combustion engines include a coil body that generates a high voltage, and a protector that holds a conductive member that electrically connects the coil body and the spark plug. The protector portion includes a cylindrical pole joint and a plug cap fitted to a tip portion of the pole joint (hereinafter referred to as “joint tip portion” as appropriate). By attaching the spark plug to the plug cap, the ignition coil and the spark plug are connected.
In such an ignition coil, a pole joint provided with a flange is disclosed (Patent Document 1).

JP 2007-218158 A

  However, the ignition coil disclosed in Patent Document 1 has a gap between the flange and the plug cap. Therefore, it becomes difficult to improve the insulation resistance between the inside and outside of the protector portion. In other words, the protector portion is designed to insulate between the conductive member held on the inside and the inner wall of the plug hole arranged outside the protector portion. Among the protector portions, the pole joint and the plug cap There is concern about a decrease in insulation resistance at the fitting portion. Because of the force when inserting the spark plug into the plug cap, the position of the plug cap with respect to the pole joint in the fitting part may shift, and a gap or the like may be generated between them. This is because the contact area may decrease and the insulation resistance may decrease. Therefore, it is desirable that the flange portion and the plug cap are brought into close contact with each other in terms of preventing displacement of the pole joint and the plug cap and ensuring insulation. However, the configuration described in Patent Document 1 is disadvantageous in terms of ensuring insulation because a gap is provided between the flange portion and the plug cap.

  Therefore, when the flange portion and the plug cap are brought into close contact with each other, air is interposed between the outer peripheral surface of the joint tip and the inner peripheral surface of the plug cap at the time of assembly or the like, and this air passage is blocked. It may be peeled off and air may remain between the joint tip and the plug cap. As a result, the insulation resistance between the inside and outside of the protector portion may be reduced at the joint portion between the pole joint and the plug cap. Furthermore, there is a possibility that the fitting strength between the pole joint and the plug cap may be reduced, or the assembling property may be deteriorated.

  The present invention has been made in view of such a background, and intends to provide an ignition coil for an internal combustion engine capable of ensuring the insulation resistance of the protector part and the fitting strength between the pole joint and the plug cap. It is.

One aspect of the present invention is an ignition coil for an internal combustion engine that includes a coil body that generates a high voltage, and a protector that holds a conductive member that electrically connects the coil body and the spark plug. There,
The protector part includes a cylindrical pole joint, and a plug cap that is fitted to a joint tip part that is an end part of the pole joint opposite to the coil body part and connects the spark plug,
The pole joint has a flange projecting to the outer peripheral side on the proximal end side of the joint distal end,
The plug cap is fitted from the outer peripheral side to the joint tip in a state of being in contact with the flange.
The ignition coil for an internal combustion engine is characterized in that a communication space is formed between the flange portion and the plug cap so as to communicate the inner peripheral side and the outer peripheral side of the opposing portion.

  In the ignition coil for an internal combustion engine, the plug cap is fitted from the outer peripheral side to the joint front end portion in a state where the plug cap is in contact with the flange portion. Thereby, the fall of the contact area of both by the position shift of a pole joint and a plug cap can be prevented, and the insulation resistance of a protector part can be ensured. That is, the contact area between the pole joint and the plug cap can be prevented from being reduced by the amount of contact between the distal end side surface of the flange and the proximal end side surface of the plug cap.

  In addition, a communication space is formed between the flange portion and the plug cap so as to allow communication between the inner peripheral side and the outer peripheral side of the opposing portions. Thereby, it can prevent that air remains between a joint front-end | tip part and a plug cap, and can ensure the insulation resistance of a protector part. That is, when the plug cap is assembled to the joint tip, even if air is interposed between the outer peripheral surface of the joint tip and the inner peripheral surface of the plug cap, the air can be released from the communication space. Thereby, the fall of the insulation resistance in the fitting part of a pole joint and a plug cap can be prevented. In addition, since the contact area between the plug cap and the flange portion can be reduced, the plug cap is likely to be locally deformed when the plug cap is pushed toward the flange portion. Therefore, the force required when assembling the plug cap to the pole joint can be reduced, and the assemblability can be improved.

  Also, by preventing air from remaining between the joint tip and the plug cap, it is possible to secure a contact area between the outer peripheral surface of the joint tip and the inner peripheral surface of the plug cap. The fitting strength between the plug cap and the plug cap can be improved.

  As described above, according to the present invention, it is possible to provide an ignition coil for an internal combustion engine that can ensure the insulation resistance of the protector portion and the fitting strength between the pole joint and the plug cap.

1 is a partial cross-sectional front view of an ignition coil for an internal combustion engine in Embodiment 1. FIG. 2 is a cross-sectional front view of a pole joint and a plug cap in Embodiment 1. FIG. FIG. 4 is another cross-sectional front view of the pole joint and the plug cap in the first embodiment. The front view of the pole joint and plug cap in Example 1. FIG. Sectional drawing of the pole joint equivalent to the VV arrow cross section of FIG. Sectional drawing of the pole joint before assembling and a plug cap in Example 1. FIG. Explanatory drawing of the example of formation of the heel side recessed part in Example 2. FIG. The front view of the pole joint and plug cap in Example 3. FIG. Sectional drawing of the plug cap equivalent to the IX-IX arrow cross section of FIG. Explanatory drawing of the example of formation of the cap side recessed part in Example 4. FIG.

  In the present specification, the side where the spark plug in the ignition coil for the internal combustion engine is fitted will be referred to as the front end side, and the opposite side will be described as the base end side.

Example 1
Examples of the ignition coil for the internal combustion engine will be described with reference to FIGS.
As shown in FIG. 1, an ignition coil 1 for an internal combustion engine of this example includes a coil main body 2 that generates a high voltage, and a conductive member 3 that electrically connects the coil main body 2 and a spark plug (not shown). And a protector portion 4 which is held inside.

  The protector 4 includes a cylindrical pole joint 41 and a plug cap 42 that is fitted to a joint tip 411 that is the end of the pole joint 41 opposite to the coil main body 2 and that connects a spark plug. . The pole joint 41 has a flange portion 412 that protrudes toward the outer peripheral side on the proximal end side of the joint distal end portion 411. As shown in FIG. 2, the plug cap 42 is fitted to the joint front end portion 411 from the outer peripheral side in a state of being in contact with the flange portion 412. As shown in FIGS. 3 to 5, a communication space 410 is formed between the flange portion 412 and the plug cap 42 so as to communicate the inner peripheral side and the outer peripheral side of the opposing portions.

  The coil body 2 is configured by housing a primary coil and a secondary coil in a coil case. As shown in FIG. 1, the coil main body 2 is formed with a high voltage output terminal 211 that outputs a high voltage generated in the coil main body 2 and a high voltage tower 21 that holds a resistor 212 therein. A connecting seal member 12 is provided between the high-pressure tower 21 and the pole joint 41 to connect the two and seal between them.

As shown in FIG. 1 to FIG. 4 and FIG. 6, the pole joint 41 has a tapered portion 413 that is inclined toward the radially outer side toward the distal end. Further, a flange portion 412 is formed on the tip side of the pole joint 41 with respect to the taper portion 413. The pole joint 41 has a joint front end portion 411 on the front end side of the flange portion 412.
The pole joint 41 is made of, for example, PPS (polyphenylene sulfide resin), PBT (polybutylene terephthalate resin), unsaturated polyester, or the like.

  The flange portion 412 has an annular shape extending outward from the outer peripheral side surface of the pole joint 41. 3-5, the collar part 412 has the collar side recessed part 412a which retracted partially in the front end side surface 412b. The heel side recessed part 412a is continuously formed from the inner peripheral end of the ridge part 412 to the outer peripheral end. Further, as shown in FIG. 5, four ridge side recesses 412a are formed at equal intervals in the circumferential direction. Each heel-side recess 412a is formed in a fan shape when viewed from the axial direction. As shown in FIGS. 3 and 4, the axial thickness of the heel-side recess 412 a is less than or equal to half the axial thickness of the ridge 412, but is not limited thereto.

  As shown in FIGS. 2 and 4, the side surface 412 b of the flange portion 412 of the pole joint 41 is provided with a flange side contact surface 412 c that contacts the plug cap 42 at a portion other than the flange side recess 412 a. When the proximal end side surface 42b of the plug cap 42 contacts the flange side contact surface 412c of the flange portion 412, a communication space 410 is formed between the flange side concave portion 412a and the proximal end side surface 42b of the plug cap 42. That is, the communication space 410 is formed by the heel-side recess 412 a formed on the tip side surface 412 b of the heel portion 412. The base end side surface 42b of the plug cap 42 is a flat surface on the same plane.

  As shown in FIG. 1 to FIG. 3 and FIG. 6, the joint front end portion 411 has an engaging convex portion 414 that protrudes from the outer peripheral surface. The plug cap 42 has an engagement recess 424 that engages with the engagement projection 414. The engaging convex portion 414 has an annular shape extending outward from the outer peripheral side surface of the joint tip portion 411. The surface on the distal end side of the engaging convex portion 414 is inclined so as to go radially inward toward the distal end.

  A plug cap 42 is fitted to the joint tip 411 of the pole joint 41. As shown in FIGS. 2, 3, and 6, the plug cap 42 has a cylindrical outer peripheral wall 421, an inner peripheral wall 422 formed inside the outer peripheral wall 421, and an outer peripheral wall 421 and an inner peripheral wall 422 at the tip. It consists of the connection part 423 connected in a part.

  The outer peripheral wall 421 has an engaging recess 424 formed on its inner peripheral surface so as to recede radially outward. As shown in FIGS. 2 and 3, the joint tip 411 is inserted between the outer peripheral wall 421 and the inner peripheral wall 422 and is in close contact with the outer peripheral wall 421. Then, the engaging convex portion 414 is engaged with the engaging concave portion 424. On the other hand, the joint front end portion 411 has a gap with the inner peripheral wall 422.

A chamfered portion 422a is formed at the distal end portion of the inner peripheral wall 422 so as to be directed radially outward toward the distal end side.
A spark plug is fitted into the inner peripheral wall 422 of the plug cap 42. When fitting the spark plug to the plug cap 42, the spark plug is fitted to the inner peripheral wall 422 using the chamfered portion 422 a of the plug cap 42 as a guide. And the terminal part of the base end of a spark plug contacts the conduction | electrical_connection member 3 inside the pole joint 41, and conduction | electrical_connection with the ignition coil 1 for internal combustion engines and a spark plug is achieved.

  The plug cap 42 is made of, for example, silicone rubber, EPDM (ethylene / propylene / diene rubber), or the like.

Next, the effect of the ignition coil 1 for the internal combustion engine of this example will be described.
In the ignition coil 1 for an internal combustion engine, the plug cap 42 is fitted to the joint tip 411 from the outer peripheral side in a state of being in contact with the flange 412. Thereby, the fall of the contact area of both by the position shift of the pole joint 41 and the plug cap 42 can be prevented, and the insulation resistance of the protector part 4 can be ensured. That is, the contact area between the pole joint 41 and the plug cap 42 is reduced by the amount of contact between the flange side contact surface 412c of the flange portion 412 and the proximal end side surface 42b of the plug cap 42. Can be prevented.

  In addition, a communication space 410 is formed between the flange portion 412 and the plug cap 42 so as to communicate the inner peripheral side and the outer peripheral side of the opposing portions. Thereby, it can prevent that air remains between the joint front-end | tip part 411 and the plug cap 42, and the insulation resistance of the protector part 4 can be ensured. That is, even when air is interposed between the outer peripheral surface of the joint front end 411 and the inner peripheral surface of the plug cap 42 (the inner peripheral surface of the outer peripheral wall 421) when the plug cap 42 is assembled to the joint front end 411. The air can be escaped from the communication space 410. Thereby, the fall of the insulation resistance in the fitting part of the pole joint 41 and the plug cap 42 can be prevented. In addition, since the contact area between the plug cap and the flange portion can be reduced, the plug cap is likely to be locally deformed when the plug cap is pushed toward the flange portion. Therefore, the force required when assembling the plug cap to the pole joint can be reduced, and the assemblability can be improved.

  Further, by preventing air from remaining between the joint tip 411 and the plug cap 42, it is possible to secure a contact area between the outer peripheral surface of the joint tip 411 and the inner peripheral surface of the plug cap 42. The fitting strength between the pole joint 41 and the plug cap 42 can be improved.

  In addition, the communication space 410 is formed by a heel-side recess 412 a formed on the tip side surface of the heel portion 412. Thereby, the communication space 410 can be formed easily and reliably.

  In addition, the joint tip 411 has an engaging convex portion 414 protruding from the outer peripheral surface, and the plug cap 42 has an engaging concave portion 424 that engages with the engaging convex portion 414. As a result, the plug cap 42 can be prevented from coming off from the joint tip 411, and the contact area between the pole joint 41 and the plug cap 42 can be prevented from being lowered due to the positional deviation between the two. 4 insulation resistance can be secured.

  In addition, when the joint tip 411 has the engaging convex portion 414 and the plug cap 42 has the engaging concave portion 424, the base end side surface 42 b of the plug cap 42 is connected to the flange side contact surface of the flange portion 412 of the pole joint 41. In order to make it contact with 412c, it is necessary to make the dimension between the engagement convex part 414 and the collar side contact surface 412c substantially the same as the dimension between the engagement concave part 424 and the base end side surface 42b. .

  However, in reality, it is difficult to manage the dimensions so that they are exactly the same. Therefore, in practice, the dimension between the engagement recess 424 and the base end side surface 42b is designed to be slightly larger than the dimension between the engagement projection 414 and the heel-side contact surface 412c, and the plug cap 42 is designed. Is fitted into the joint tip 411 so that the portion between the engagement recess 424 and the base end side surface 42b is slightly compressed and deformed in the axial direction. Here, since the communication space 410 exists between the base end side surface 42 b of the plug cap 42 and the flange portion 412, the base end side surface 42 b of the plug cap 42 is easily deformed.

  That is, by pushing the plug cap 42 toward the flange portion 412, a part of the base end side surface 42 b of the plug cap 42 bites into the communication space 410. Thereby, the part between the engagement recessed part 424 and the base end side surface 42b in the plug cap 42 is easy to compressively deform in an axial direction. As a result, it becomes easy to reliably contact the proximal end side surface 42b of the plug cap 42 to the heel side contact surface 412c while securely engaging the engagement convex portion 414 and the engagement concave portion 424.

  As described above, according to this example, it is possible to provide an ignition coil for an internal combustion engine that can ensure the insulation resistance of the protector part and the fitting strength between the pole joint and the plug cap.

(Example 2)
In this example, as shown in FIG. 7, the shape, the number of formed portions, and the like of the heel side recesses 412 a are changed. Specifically, the heel side recess 412a in this example is formed in an arc shape so as to open in opposite directions on both sides of the pole joint 41 in the direction orthogonal to the axial direction.
Of the reference numerals used in this example or the drawings relating to this example, the same reference numerals as those used in the first embodiment denote the same components as in the first embodiment unless otherwise specified.
Also in this example, the same effect as Example 1 can be obtained.

(Example 3)
In this example, as shown in FIGS. 8 and 9, the communication space 420 is formed by a cap-side recess 42 a formed on the proximal end side surface 42 b of the plug cap 42. That is, the plug cap 42 is formed with a cap-side recess 42 a that partially recedes on the base end side surface of the outer peripheral wall 421. The cap-side recess 42a is continuously formed from the inner peripheral end of the outer peripheral wall 421 to the outer peripheral end. Moreover, as shown in FIG. 9, the four cap side recessed parts 42a are formed in the circumferential direction at equal intervals. Each cap-side recess 42a is formed to have a fan shape when viewed from the axial direction. As shown in FIG. 8, the axial thickness of the cap-side recess 42 a is less than half of the axial thickness of the flange portion 412, but is not limited thereto.

  The base end side surface 42b of the plug cap 42 is provided with a cap side contact surface 42c that contacts the flange portion 412 of the pole joint 41 at a portion other than the cap side recess 42a. The cap-side contact surface 42c comes into contact with the distal end side surface 412b of the flange portion 412 so that a communication space 420 is formed between the distal end side surface 412b of the flange portion 412 and the cap side recessed portion 42a. That is, the communication space 420 is formed by the cap-side recess 42 a formed on the base end side surface 42 b of the plug cap 42. In this example, the collar part 412 is not formed with a collar part concave part (see reference numeral 412a in FIG. 4). And the front end side surface 412b of the collar part 412 is a flat surface of the same plane shape.

  Among the symbols used in this example or the drawings relating to this example, the same symbols as those used in the first embodiment represent the same components as those in the first embodiment unless otherwise specified.

In this example, a cap-side recess 42 a is formed on the proximal end side surface 42 b of the plug cap 42. Therefore, when the plug cap 42 is molded, the plug cap 42 can be easily removed.
In addition, the same effects as those of the first embodiment are obtained.

Example 4
In this example, as shown in FIG. 10, the shape and the number of cap-side recesses 42 a are changed. Specifically, the cap-side recesses 42a in the present example have a substantially rectangular shape, and eight are formed at equal intervals in the circumferential direction.
Of the reference numerals used in this example or the drawings relating to this example, the same reference numerals as those used in the first embodiment denote the same components as in the first embodiment unless otherwise specified.
Also in this example, it is possible to obtain the same effect as that of the third embodiment.

  In addition, the shape of the heel side recessed part 412a and the cap side recessed part 42a, the number of formations, etc. can be variously changed in addition to the above-described embodiment, and are not particularly limited. For example, like the heel side recess 412a of the second embodiment, the cap side recess 42a may be formed in an arc shape with the opening direction facing each other at both ends of the plug cap 42 in the direction orthogonal to the axial direction. Further, like the cap-side recess 42a of the fourth embodiment, the heel-side recesses 412a may be formed in a substantially rectangular shape, and may be formed at regular intervals in the circumferential direction.

DESCRIPTION OF SYMBOLS 1 Ignition coil for internal combustion engines 2 Coil main-body part 3 Conductive member 4 Protector part 41 Pole joint 410,420 Communication space 411 Joint front-end | tip part 412 Gutter part 42 Plug cap

Claims (4)

An internal combustion engine having a coil main body (2) for generating a high voltage and a protector (4) holding a conductive member (3) for electrically connecting the coil main body (2) and the spark plug. Ignition coil (1) for
The protector part (4) is fitted into a cylindrical pole joint (41) and a joint tip part (411) which is the end of the pole joint (41) opposite to the coil body part (2). And a plug cap (42) for connecting the spark plug,
The pole joint (41) has a flange portion (412) protruding toward the outer peripheral side on the base end side of the joint distal end portion (411),
The plug cap (42) is fitted to the joint tip (411) from the outer peripheral side in contact with the flange (412),
A communication space (410, 420) is formed between the flange portion (412) and the plug cap (42) to communicate between the inner peripheral side and the outer peripheral side of the opposing portions. An ignition coil (1) for an internal combustion engine.   2. The internal combustion engine for an internal combustion engine according to claim 1, wherein the communication space (410) is formed by a heel-side recess (412 a) formed in a tip side surface (412 b) of the heel portion (412). Ignition coil (1).   The internal combustion engine according to claim 1 or 2, wherein the communication space (420) is formed by a cap-side recess (42a) formed in a proximal end side surface (42b) of the plug cap (42). Ignition coil for engine (1).   The joint front end portion (411) has an engaging convex portion (414) formed to project from the outer peripheral surface, and the plug cap (42) engages with the engaging convex portion (414). The ignition coil (1) for an internal combustion engine according to any one of claims 1 to 3, characterized by comprising:

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