JP2018182304A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil for an internal combustion engine capable of facilitating attachment / detachment of a joint to a spark plug. An ignition coil 1 for an internal combustion engine has a primary coil 11, a secondary coil 12, a case 2, and a joint 3. The primary coil 11 and the secondary coil 12 are magnetically coupled to each other. The case 2 has a case main body 20 that houses the primary coil 11 and the secondary coil 12, and a tubular high-pressure tower 23 that protrudes from the case bottom wall 21 of the case main body 20. The joint 3 is fitted to the high pressure tower 23 and the spark plug 13. The joint 3 has a cylindrical shape. Between the high-pressure tower 23 and the joint 3, a communication space 5 that communicates the inner space 41 of the high-pressure tower 23 and the joint 3 and the outer space 42 of the high-pressure tower 23 and the joint 3 is formed. [Selection diagram] Fig. 1

Description

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

  Patent Document 1 discloses, as an ignition coil for an internal combustion engine, one having a primary coil and a secondary coil magnetically coupled to each other, a case for housing them, and a rubber joint fitted in the case. It is done. The case has an axially projecting cylindrical high pressure tower. Also, the joint is fitted to the case so as to cover the high pressure tower of the case. The spark plug is inserted into and fitted to the tip of the joint.

  The ignition coil described in Patent Document 1 has a plurality of recesses formed on the inner peripheral surface of the joint where the spark plug is disposed, in order to facilitate removal of the spark plug from the joint. Thereby, the contact area between the inner peripheral surface of the joint and the spark plug is reduced, and the force required when the spark plug is detached from the joint is reduced.

Japanese Patent Application Laid-Open No. 8-130131

  However, in the ignition coil described in Patent Document 1, there is room for improvement from the viewpoint of facilitating the desorption of the joint with respect to the spark plug.

  That is, in the ignition coil described in Patent Document 1, for example, in the ignition coil fitted with the spark plug, when the spark plug is pulled out from the joint, the joint is generally made of a soft material such as rubber, As the spark plug is pulled out of the joint, the space in the joint becomes negative pressure. Therefore, as the spark plug is withdrawn from the joint, the force required to withdraw the spark plug from the joint is gradually increased. Furthermore, the negative pressure in the space in the joint causes the diameter of the joint to be reduced, and the fitting force between the joint and the case and the spark plug becomes stronger. This also increases the force required to pull the spark plug out of the joint.

  Similarly, for example, when inserting the spark plug into the tip of the joint of the ignition coil, the space in the joint is compressed as the spark plug is inserted into the joint. Therefore, as the spark plug is inserted into the joint of the ignition coil, the force required to insert the spark plug into the joint increases.

  In recent years, an ignition coil may be attached to an engine having a bent plug hole instead of a linear plug hole, or an engine having a relatively long plug hole. Correspondingly, the joints of the ignition coil may be formed in a bent or relatively long shape. In this case, the removability of the joint with respect to the spark plug is more likely to deteriorate. Therefore, the need to solve the problem of facilitating the detachment of the joint with respect to the spark plug becomes high.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an ignition coil for an internal combustion engine capable of facilitating desorption of a joint with respect to a spark plug.

One aspect of the present invention relates to a primary coil (11) and a secondary coil (12) magnetically coupled to one another.
A case body (20) accommodating the primary coil and the secondary coil, and a case (2) having a cylindrical high-pressure tower (23) projecting from a case bottom wall (21) of the case body;
And a cylindrical joint (3) fitted to the high pressure tower and the spark plug (13);
A communication space (5) is formed between the high pressure tower and the joint, which communicates the high pressure tower and the inner space (41) of the joint, and the high pressure tower and the outer space (42) of the joint. And an ignition coil (1) for an internal combustion engine.

  In the ignition coil for the internal combustion engine, the communication space is formed between the high pressure tower and the joint. Therefore, at the time of attachment and detachment of the joint to the spark plug, it is possible to suppress the fluctuation of the air pressure in the joint. Thus, the joint can be easily detached from the spark plug.

As described above, according to the above aspect, it is possible to provide an ignition coil for an internal combustion engine that can facilitate the detachment of the joint with respect to the spark plug.
The reference numerals in parentheses described in the claims and the means for solving the problems indicate the correspondence with the specific means described in the embodiments described later, and the technical scope of the present invention is limited. It is not a thing.

FIG. 2 is a cross-sectional view of the ignition coil in the first embodiment. FIG. 2 is an enlarged cross-sectional view of the vicinity of the high pressure tower of the ignition coil in the first embodiment. FIG. 2 is an enlarged cross-sectional view of the joint in the axial direction parallel to the joint in Embodiment 1 and passing through a space forming groove; FIG. 3 is an enlarged cross-sectional view of the joint in the axial direction parallel to the joint in Embodiment 1 and not passing through a space forming groove; FIG. 2 is a top view of a joint in Embodiment 1; FIG. 2 is a cross-sectional view of the igniter in which the ignition coil is attached in the first embodiment. 10 is an enlarged cross-sectional view of the vicinity of a high pressure tower of an ignition coil in Embodiment 2. FIG. FIG. 7 is a top view of a joint in a second embodiment. The enlarged front view which looked at the joint from the horizontal direction in Embodiment 2. FIG. FIG. 7 is a top view of an ignition coil in a second embodiment. The expanded sectional view of the ignition device in the state before axial force of a bolt acts on a case in Embodiment 2. FIG. The expanded sectional view of the ignition device with which the ignition coil was attached in Embodiment 2. FIG. FIG. 13 is a top view showing a modified form of Embodiment 2; FIG. 13 is a top view showing another variation of the second embodiment. FIG. 13 is a top view showing still another modified embodiment of the second embodiment. FIG. 14 is a top view of a joint in a third embodiment. The expanded sectional view which is an axially parallel cross section of the joint in Embodiment 3, and passes through a space formation groove. FIG. 16 is an enlarged cross-sectional view of the vicinity of a high pressure tower of an ignition coil in a fourth embodiment. The expanded sectional view which is an axially parallel cross section of the joint in Embodiment 4, and passes through a space formation groove. The top view of the joint in a 4th embodiment. FIG. 18 is a bottom view of the case in the fourth embodiment. The expanded sectional view of a high pressure tower periphery of an ignition coil in Embodiment 5. FIG. 16 is an enlarged cross-sectional view around the protrusion and the accommodation recess in the fifth embodiment. The bottom view of the case in a 5th embodiment. FIG. 21 is a top view of a joint in a fifth embodiment. The expanded sectional view of the ignition device in the state before axial force of a bolt acts on a case in Embodiment 5. FIG. The expanded sectional view of the ignition device with which the ignition coil was attached in Embodiment 5. FIG. FIG. 16 is an enlarged cross-sectional view of the vicinity of the protrusion and the accommodation recess of the ignition device in the fifth embodiment. The bottom view of a case which shows the modification of Embodiment 5. FIG. FIG. 16 is an enlarged cross-sectional view of the vicinity of a high pressure tower of an ignition coil in a sixth embodiment. The expanded sectional view of the case in Embodiment 6. FIG. The bottom view of the case in a 6th embodiment. The figure which looked at the ignition coil in Embodiment 6 from the protrusion side of the flange in a case. The expanded sectional view of a high pressure tower periphery of an ignition coil in a 7th embodiment. The expanded sectional view of the ignition device with which the ignition coil was attached in Embodiment 7. FIG. The expanded sectional view of a high pressure tower periphery of an ignition coil in Embodiment 8. The expanded sectional view of the ignition device with which the ignition coil was attached in Embodiment 8. FIG. The expanded sectional view of the high pressure tower periphery of an ignition coil in Embodiment 9. The expanded sectional view which is an axially parallel cross section of the joint in Embodiment 9, and does not pass through a space formation groove. The figure which looked at the joint in embodiment 9 from the front of a penetration hole. The top view of the joint in Embodiment 9. FIG. The expanded sectional view of the ignition device in the state before axial force of a bolt acts on a case in Embodiment 9. FIG. The expanded sectional view of the ignition device with which the ignition coil was attached in Embodiment 9. FIG. The expanded sectional view of a high pressure tower periphery of an ignition coil in Embodiment 10. FIG. The top view of the joint in Embodiment 10. FIG. The expanded sectional view which is an axially parallel cross section of the joint in Embodiment 10, and does not pass through a space formation groove. The front view which looked at the high pressure tower periphery of the case of the ignition coil in Embodiment 10 from the front. The expanded sectional view of the ignition device in the state before axial force of a bolt acts on a case in Embodiment 10. FIG. FIG. 49 is an enlarged view of the area around the in-groove rib in FIG. 48. The expanded sectional view of the ignition device with which the ignition coil was attached in Embodiment 10. FIG. The enlarged view around a rib in a groove in FIG.

(Embodiment 1)
Embodiments of an ignition coil for an internal combustion engine will be described using FIGS. 1 to 6.
The ignition coil 1 for an internal combustion engine of the present embodiment has a primary coil 11 and a secondary coil 12, a case 2 and a joint 3 as shown in FIG. The primary coil 11 and the secondary coil 12 are magnetically coupled to each other. The case 2 has a case main body 20 accommodating the primary coil 11 and the secondary coil 12, and a cylindrical high-pressure tower 23 projecting from the case bottom wall 21 of the case main body 20. As shown in FIG. 6, the joint 3 is fitted to the high pressure tower 23 and the spark plug 13. As shown in FIGS. 1 and 2, the joint 3 has a tubular shape. A communication space 5 is formed between the high pressure tower 23 and the joint 3 to connect the high pressure tower 23 and the inner space 41 of the joint 3 with the high pressure tower 23 and the outer space 42 of the joint 3.

  Hereinafter, the projecting direction of the high pressure tower 23 from the case main body 20 is referred to as an axial direction Z. Further, in the axial direction Z, the side where the high pressure tower 23 protrudes from the case main body 20 is referred to as the lower side, and the opposite side is referred to as the upper side.

  The ignition coil 1 of the present embodiment is connected to a spark plug 13 installed in an internal combustion engine such as a car or a cogeneration, and is used as a means for applying a high voltage to the spark plug 13. As shown in FIG. 6, the end of the spark plug 13 on the side opposite to the side on which the joint 3 of the ignition coil 1 is mounted protrudes into the combustion chamber 104 of the internal combustion engine.

  As shown in FIG. 1, the case body 20 has a case bottom wall 21 formed in a surface direction orthogonal to the axial direction Z, and a case side wall 22 extending upward from the peripheral edge of the case bottom wall 21. The case body 20 has an opening at the upper end of the case side wall 22. The case body 20 has a flange 24 projecting in a direction perpendicular to the axial direction Z. As described later, the flange 24 is fixed to the internal combustion engine. The flange 24 has a bolt insertion hole 241 formed to penetrate in the axial direction Z. Further, the flange 24 has a bush 242 fitted in the bolt insertion hole 241. The bush 242 is formed of a metal in a tubular shape.

  The projecting direction of the flange 24 in the case main body 20 is referred to as a lateral direction X. Further, in the lateral direction X, the side of the case body 20 from which the flange 24 protrudes is referred to as the X1 side, and the opposite side is referred to as the X2 side. Further, a direction orthogonal to both the axial direction Z and the lateral direction X is referred to as a longitudinal direction Y.

  The case body 20 has a connector 25 projecting on the side opposite to the side where the flange 24 protrudes in the lateral direction X (that is, on the X2 side). The connector 25 connects the ignition coil 1 and the external device by connecting an external connector which is an end of a cable connected to the external device, for example.

  A circular opening 210 penetrating in the axial direction Z is formed in a substantially central portion of the case bottom wall 21. The high-pressure tower 23 is formed so as to project downward from the peripheral edge of the opening 210.

  The high pressure tower 23 has a substantially cylindrical shape. As shown in FIG. 2, the high pressure tower 23 has a tower upper portion 231 formed at its upper end, and a tower lower portion 232 extending downward from the tower upper portion 231 and thinner than the tower upper portion 231. Have. The lower surface 231a of the tower top 231 faces downward. The tower lower portion 232 is extended downward from the inner peripheral end of the lower surface 231 a of the tower upper portion 231. The tower lower portion 232 has a retaining portion 232 a that protrudes to the outer peripheral side in the radial direction of the high pressure tower 23. The retaining portion 232 a is formed substantially at the center of the lower tower portion 232 in the axial direction Z. The retaining portion 232 a has a role of making it difficult for the joint 3 fitted to the high pressure tower 23 to come off the high pressure tower 23.

  The joint 3 is fitted to the high pressure tower 23 from the lower side of the high pressure tower 23. The joint 3 covers the high pressure tower 23 from the outer peripheral side of the high pressure tower 23.

  The joint 3 has a case bottom wall 21 and a joint upper end 31 opposed in the axial direction Z. The joint upper end portion 31 is formed so as to spread on the outer peripheral side in the radial direction at the upper end portion of the joint 3. The joint upper end portion 31 has an annular shape when viewed in the axial direction Z. Hereinafter, the surface of the joint upper end 31 facing the case bottom wall 21 is referred to as a first opposing surface 311, and the surface of the case bottom wall 21 facing the joint upper end 31 is referred to as a bottom wall lower surface 211. In the present embodiment, the first opposing surface 311 and the bottom wall lower surface 211 are in surface contact with each other.

  The joint 3 has a second opposing surface 312 opposed in the axial direction Z to the lower end surface 232 b of the tower lower portion 232 of the high pressure tower 23. The lower end surface 232 b of the tower lower portion 232 and the second opposing surface 312 are opposed to each other at an interval in the axial direction Z. That is, a space 60 is formed between the lower end surface 232 b of the tower lower portion 232 and the second opposing surface 312 in the axial direction Z. The space 60 can improve the air permeability of the space forming groove 32 described later. When air permeability of the space forming groove 32 can be sufficiently secured by the lower side groove 32a of the space forming groove 32 described later, a distance between the lower end surface 232b of the tower lower portion 232 and the second opposing surface 312 in the axial direction Z It does not have to be.

  As shown in FIGS. 2 to 5, in the present embodiment, at least a part of the communication space 5 is inside the space forming groove 32 formed in the joint 3. A groove-shaped space forming groove 32 is continuously formed from the inner space 41 of the high pressure tower 23 and the joint 3 to the outer space 42 on the surface facing the high pressure tower 23 in the joint 3. Constitute the communication space 5. In the present embodiment, the space forming groove 32 is also formed in the first opposing surface 311 of the joint upper end portion 31. Further, the space forming groove 32 is also formed on the second opposing surface 312 of the joint 3. In the present embodiment, the space forming groove 32 connects the lower side groove 32 a provided in the second opposing surface 312, the upper side groove 32 c provided in the first opposing surface 311, and the lower side groove 32 a and the upper side groove 32 c. And an intermediate groove 32 b formed on the inner wall surface of the joint 3. At the end of the space forming groove 32 in the longitudinal direction, a member that allows air to pass and does not allow liquid to flow, or a valve mechanism may be provided.

  As shown in FIG. 2, in the present embodiment, of the surface of the joint 3 facing the case 2 including the high pressure tower 23, substantially the entire region excluding the region where the space forming groove 32 is formed and the second opposite surface 312. Is in surface contact with the surface of the case 2.

  As shown in FIG. 1, in the case main body 20, a primary coil 11, a secondary coil 12 disposed on the outer peripheral side of the primary coil 11, and a core 14 disposed inside the primary coil 11 and the secondary coil 12. , And a connection terminal 15 connected to one end of the secondary coil 12. A metal high-pressure output terminal 16 is fitted inside the high-pressure tower 23. The high voltage output terminal 16 is connected to the secondary coil 12 via the connection terminal 15 at the upper side. The high voltage output terminal 16 is fitted inside the tower upper portion 231 so as to close the inner space of the tower upper portion 231 from the upper side.

  And in the case main body 20, the filling resin 17 is filled. In the case body 20, housing components such as the primary coil 11, the secondary coil 12, and the connection terminal 15 are sealed in the filling resin 17. The high pressure output terminal 16 also has a role of preventing the filling resin 17 from leaking downward from the high pressure tower 23.

  Inside the high pressure tower 23 and the joint 3, a coil spring 18 capable of elastic expansion and contraction in the axial direction Z is inserted. The upper end of the coil spring 18 is in pressure contact with the lower surface of the high voltage output terminal 16, whereby the coil spring 18 and the high voltage output terminal 16 are also electrically connected. Although not shown, the coil spring 18 is positioned in the axial direction Z with respect to the joint 3.

Next, as shown in FIG. 6, an ignition device 10 in which an ignition coil 1 for an internal combustion engine is assembled to an engine head 101 will be described.
As shown in FIG. 6, the engine head 101 is formed with a plug hole 105 through which the ignition coil 1 is inserted. The plug hole 105 is open toward the upper side, and the lower side is closed by the closed wall portion 102. The closed wall portion 102 is formed with a female screw hole 102 a for screwing the spark plug 13. Then, the spark plug 13 is screwed into the female screw hole 102 a, and the spark plug 13 is attached to the engine head 101. The tip of the spark plug 13 is exposed to the combustion chamber 104 of the internal combustion engine.

  The ignition coil 1 is disposed by inserting the joint 3 into the plug hole 105. The lower end portion of the joint 3 is fitted so as to cover the upper end portion of the spark plug 13 from the outer peripheral side. Thus, the lower side of the high pressure tower 23 and the inner space 41 of the joint 3 is closed by the spark plug 13 and the upper side is closed by the high voltage output terminal 16. Here, the inner space 41 is not completely sealed, and the inner space 41 and the outer space 42 communicate with each other through the communication space 5. Further, the lower end portion of the coil spring 18 is in pressure contact with a terminal formed at the base end portion of the spark plug 13. Thereby, the secondary coil 12 of the ignition coil 1 and the spark plug 13 are electrically connected.

  The ignition coil 1 is disposed such that the joint upper end 31 is placed on a portion of the upper surface of the engine head 101 around the plug hole 105. In the present embodiment, the engine head 101 has an annular lip 106 projecting upward from the inner peripheral end of the plug hole 105. The ignition coil 1 is mounted such that the joint upper end 31 is in contact with the entire upper end surface 106 a of the lip 106.

  Further, a boss 107 for bolting the ignition coil 1 is formed on the engine head 101. The ignition coil 1 is fastened and fixed to the engine head 101 by inserting the bolt 108 into the bush 242 of the flange 24 and screwing the bolt 108 into a screw hole 107 a formed in the boss 107.

Next, how the ignition coil 1 is attached to the internal combustion engine will be described.
First, the spark plug 13 is screwed into the female screw hole 102 a of the engine head 101. Next, the ignition coil 1 is inserted into the plug hole 105 from the joint 3 side. Then, the upper end of the spark plug 13 is inserted into the lower end of the joint 3, and the ignition coil 1 is pushed toward the spark plug 13 until the joint upper end 31 abuts on the upper end surface 106 a of the lip 106 of the engine head 101.

  Then, the bolt 108 is inserted into the bush 242 of the flange 24, and the bolt 108 is screwed into the screw hole 107 a of the boss 107. As the bolt 108 is screwed in, the spark plug 13 is inserted into the inside of the joint 3 and the axial force of the bolt 108 causes the spark plug 13 and the joint 3 to be fitted.

  Here, as described above, the upper end of the inner space 41 is closed by the high voltage output terminal 16 and the lower end is closed by the upper end of the spark plug 13. Therefore, as the spark plug 13 is inserted into the joint 3, the air in the inner space 41 is pushed out of the inner space 41 through the communication space 5 to the outer space 42. Thus, when fitting the joint 3 to the spark plug 13, the joint 3 can be easily fitted to the spark plug 13 without the pressure in the inner space 41 becoming excessively high. Then, by screwing the bolt 108 to the boss 107 until the lower surface of the flange 24 abuts on the upper surface of the boss 107, the joint upper end 31 is pressed against the upper end surface 106 a of the lip 106 and the upper end surface 106 a of the lip 106 Close to the entire surface.

Next, how the ignition coil 1 is removed from the internal combustion engine will be described.
First, the bolt 108 is removed from the boss 107 and the flange 24. Then, the ignition coil 1 is pulled out of the spark plug 13. At this time, since the inner space 41 expands as the ignition coil 1 is pulled out of the spark plug 13, external air flows into the inner space 41 via the communication space 5. As a result, when the ignition coil 1 is pulled out of the spark plug 13, the ignition coil 1 can be easily pulled out of the spark plug 13 without an excessive negative pressure in the inner space 41.

Next, the operation and effect of the present embodiment will be described.
In the ignition coil 1 for an internal combustion engine, a communication space 5 is formed between the high pressure tower 23 and the joint 3. Therefore, when the joint 3 is detached from the spark plug 13, the air pressure in the inner space 41 of the joint 3 is approximately equal to the air pressure in the outer space 42. Therefore, the joint 3 can be easily attached to and removed from the spark plug 13. That is, when the spark plug 13 is desorbed from the ignition coil 1, the load at the desorbing operation can be reduced, and the time when the load at the desorbing operation increases can be shortened.

  Further, at least a part of the communication space 5 is inside the space forming grooves 32 and 233 formed in the joint 3. Therefore, the communication space 5 can be easily formed. In addition, it can be suppressed that the communication space 5 is formed excessively large. This makes it easy to ensure the insulation and water tightness inside and outside the joint 3.

  As described above, according to the present embodiment, it is possible to provide an ignition coil for an internal combustion engine capable of facilitating the detachment of the joint with respect to the spark plug.

Second Embodiment
This embodiment is an embodiment in which a bottom wall side space 51 described later constitutes a part of the communication space 5, as shown in FIGS. The case bottom wall 21 and the joint upper end 31 face each other at an interval in the axial direction Z. A bottom wall side space 51 adjacent to the outer space 42 is formed between the case bottom wall 21 and the joint upper end 31. In the present embodiment, the communication space 5 has a bottom wall side space 51, a space inside the intermediate groove 32b, and a space inside the lower groove 32a. In addition, in FIG. 10, the outline position of the 1st opposing surface 311 of the joint upper end part 31 and the outline position of the protrusion part 8 mentioned later are represented with the broken line.

  As shown in FIG. 7, the bottom wall side space 51 is formed between the bottom wall lower surface 211 of the case bottom wall 21 and the first opposing surface 311 of the joint upper end portion 31 in the axial direction Z. The bottom wall side space 51 is formed to surround the high pressure tower 23 from the entire circumference, and the shape viewed from the axial direction Z is annular.

  At least one of the case 2 and the joint 3 has a protrusion 8 that protrudes in the axial direction Z toward the mating side and that abuts on the mating side. In the present embodiment, at least one of the case bottom wall 21 and the joint upper end portion 31 has the projecting portion 8. As shown in FIGS. 7 to 9, the protrusion 8 is formed at the joint upper end 31. The projecting portion 8 is formed such that a part of the first opposing surface 311 of the joint upper end portion 31 protrudes upward. As shown in FIG. 7, the upper end of the protrusion 8 abuts on the bottom wall lower surface 211 of the case bottom wall 21. The protrusion 8 positions the joint 3 and the case 2 in the axial direction Z. The dimension in the axial direction Z of the bottom wall side space 51 is the same as the dimension of the protrusion 8. The protruding portion 8 is integrally formed with a portion of the joint 3 other than the protruding portion 8. That is, the protrusion 8 is also made of rubber and is configured to be elastically deformable.

  As shown in FIGS. 8 and 9, the joint upper end portion 31 is provided with two projecting portions 8. As shown in FIG. 8, the protruding portion 8 is a ridge that can be elastically deformed in the axial direction Z. In the present embodiment, the protrusion 8 is elongated in the lateral direction X and has a thin shape in the longitudinal direction Y. The two protrusions 8 are arranged side by side in the longitudinal direction Y.

  Here, as shown in FIG. 7, it is a part of the communication space 5 and a portion on the inner space 41 side of the bottom wall side space 51 and the bottom wall side space 51 in the communication space 5 (that is, communication in FIG. 7). The boundary between the space 5 and the portion enclosed by the broken line 5a) is defined as the boundary B. That is, the boundary between the bottom wall side space 51 and the space inside the intermediate groove 32 b is the boundary portion B. The projecting portion 8 is formed around the boundary B so as to prevent foreign matter such as water and dust from entering the inner space 41 from the outer space 42 via the boundary B.

  Specifically, the boundary portion B is formed on the X1 side of the central axis of the high pressure tower 23. The boundary portion B is disposed on a straight line indicated by a two-dot chain line in FIG. 10 connecting the central axis of the high pressure tower 23 and the central axis of the bolt insertion hole 241 of the flange 24 when viewed in the axial direction Z. As shown in FIG. 8, in the lateral direction X, the two protrusions 8 are formed in the vicinity of the boundary B on the X1 side. In the longitudinal direction Y, the two protrusions 8 are located on both sides in the longitudinal direction Y at the boundary B. As shown in FIG. 10, when viewed in the axial direction Z, the two projecting portions 8 connect the central axis of the high pressure tower 23 and the central axis of the bolt insertion hole 241 of the flange 24 as shown by the two-dot chain line in FIG. The straight line is formed so as to be sandwiched from both sides in the longitudinal direction Y.

  As shown in FIG. 10, when viewed from the axial direction Z, the projecting portion 8 is a flange 24 more than the central axis of the high pressure tower 23 in the alignment direction of the central axis of the high pressure tower 23 and the flange 24 (that is, the lateral direction X). Located on the side. Here, in FIG. 10, a straight line passing through the central axis of the high pressure tower 23 and extending in the longitudinal direction Y is represented by a dashed-dotted line. That is, in the present embodiment, the protrusion 8 is formed closer to the X1 side than the alternate long and short dash line in FIG.

  As shown in FIG. 7, in the present embodiment, the lower surface 231 a of the tower upper portion 231 and the joint 3 are opposed to each other at an interval in the axial direction Z. The surface of the joint 3 facing the lower surface 231 a of the tower upper portion 231 in the axial direction Z is referred to as a third opposing surface 313. An upper slide space 62 is formed between the lower surface 231 a of the tower upper portion 231 and the third opposing surface 313 of the joint 3. In addition, a lower slide space 61 is formed below the retaining portion 232a. That is, the retaining portion 232 a is opposed to the joint 3 in the axial direction Z via the lower lower slide space 61. Each of the length of the upper slide space 62 in the axial direction Z and the length of the lower slide space 61 is formed to be longer than the length of the bottom wall side space 51 in the axial direction Z.

Next, how the ignition coil 1 of the present embodiment is attached to an internal combustion engine as shown in FIGS. 11 and 12 will be described.
As in the first embodiment, the ignition coil 1 is inserted into the plug hole 105 from the joint 3 side, and the upper end of the spark plug is inserted into the lower end of the joint 3. Then, as in the first embodiment, the upper end of the spark plug is inserted into the lower end of the joint 3, and the ignition coil 1 is pushed until the joint upper end 31 abuts on the upper end surface 106 a of the lip 106 of the engine head 101.

  Then, the bolt 108 is inserted into the bush 242 of the flange 24 and the bolt 108 is screwed into the screw hole 107 a of the boss 107 until the head 108 a of the bolt 108 abuts on the upper surface of the flange 24. This state is shown in FIG. In this state, the axial force of the bolt 108 does not act on the ignition coil 1. Therefore, in the state shown in FIG. 11, the protrusion 8 is not elastically deformed, and the state where the bottom wall side space 51 is formed is maintained.

  Then, the bolt 108 is further screwed into the boss 107 from the state of FIG. Thus, the axial force of the bolt 108 is transmitted to the case 2 of the ignition coil 1. Thereby, the case 2 moves downward so as to approach the joint 3. Here, as described above, since the joint upper end 31 is in contact with the lip 106, the downward movement of the joint 3 is limited even if the case 2 moves downward due to the axial force of the bolt 108. Be done. Therefore, as the bolt 108 is screwed into the boss 107, the projection 8 is elastically deformed so as to be compressed in the axial direction Z. Thus, the bottom wall side space 51 contracts as the bolt 108 is screwed into the boss 107.

  Then, by screwing until the lower surface of the flange 24 of the case 2 abuts on the upper surface of the boss 107, as shown in FIG. 12, the bottom wall side space (see reference numeral 51 in FIG. 11) disappears or substantially disappears (for example, The protrusion 8 is elastically deformed to such an extent that the length in the axial direction Z of the bottom wall side space 51 is 0.02 mm to 0.5 mm. That is, in the present embodiment, the communication space 5 formed in the state before the ignition coil 1 is attached to the internal combustion engine is closed or substantially closed in the state where the ignition coil 1 is attached to the internal combustion engine .

Next, how the ignition coil 1 is removed from the internal combustion engine will be described.
As in the first embodiment, the bolt 108 is first removed from the boss 107 and the flange 24. As a result, the axial force of the bolt 108 acting on the case 2 disappears. Therefore, the case 2 is pressed by the restoring force of the compressed projection 8 and moves away from the joint 3. As a result, the bottom wall side space 51 is again formed between the case bottom wall 21 and the joint upper end portion 31 or a bottom larger than the bottom wall side space 51 formed when the bolt 108 is screwed. The wall side space 51 is formed, and the communication space 5 and the outer space 42 are communicated with each other.

  Then, the ignition coil 1 is pulled out of the spark plug 13. At this time, since the inner space 41 expands as the ignition coil 1 is pulled out of the spark plug 13, external air flows into the inner space 41 via the communication space 5. As a result, when the ignition coil 1 is pulled out of the spark plug 13, the ignition coil 1 can be easily pulled out of the spark plug 13 without an excessive negative pressure in the inner space 41.

Others are the same as in the first embodiment.
In addition, the code | symbol same as the code | symbol used in already-appeared embodiment among the code | symbol used in Embodiment 2 or subsequent ones represents the component similar to the thing in already-appeared embodiment, etc., unless shown.

  In the present embodiment, the bottom wall side space 51 constitutes a part of the communication space 5. Therefore, it is easy to easily form a part of the communication space 5 and to improve the productivity of the ignition coil 1.

  The joint 3 also has a protrusion 8 that protrudes in the axial direction Z toward the case 2 and that abuts on the case 2. Therefore, the projection 8 can be used as positioning in the axial direction Z between the case 2 and the joint 3, which facilitates the formation of the bottom wall side space 51.

  In addition, the joint upper end 31 has a protrusion 8. Therefore, in the joint 3, the projection 8 is easily formed.

  In addition, the projecting portion 8 is a protrusion which is elastically deformable in the axial direction Z and extends in a direction orthogonal to the axial direction Z. Therefore, in the state where the ignition coil 1 is not fastened to the internal combustion engine, the presence of the bottom wall side space 51 is maintained by the presence of the projection 8, but in the state where the ignition coil 1 is attached to the internal combustion engine The protrusion 8 can be easily elastically deformed by the axial force of the bolt 108 and the like, and the bottom wall side space 51 can be easily erased or substantially erased. Therefore, in the state where the ignition coil 1 is attached to the internal combustion engine, foreign matter such as moisture or dust can be suppressed from entering the inner space 41 from the outer space 42 of the ignition coil 1 through the communication space 5. Thereby, it is possible to prevent the high voltage (for example, 10 to 50 kV) generated at the high voltage output terminal 16 from being leaked from the inside of the joint 3 to the outside due to the foreign matter entering the inside of the joint 3. Further, rusting of metal parts (for example, the coil spring 18 and terminals formed at the base end of the spark plug 13) disposed in the joint 3 can be prevented, whereby the ignition coil 1 and the spark plug 13 can be prevented. It is possible to avoid conduction failure between

  Further, when viewed from the axial direction Z, the projecting portion 8 is located closer to the flange 24 than the central axis of the high pressure tower 23 in the alignment direction of the central axis of the high pressure tower 23 and the flange 24. Therefore, when the ignition coil 1 is attached to the internal combustion engine, the axial force of the bolt 108 inserted into the bolt insertion hole 241 of the flange 24 is easily transmitted to the projection 8. Therefore, the projecting portion 8 is easily elastically deformed, and in the state of being attached to the internal combustion engine, the communication space 5 is easily closed.

In addition, the projecting portion 8 is formed around the boundary B so as to suppress foreign matter from entering the inner space 41 from the outer space 42 via the boundary B. Therefore, even if foreign matter intrudes from the outer space 42 into the bottom wall side space 51, the projection 8 prevents the foreign matter from entering the inner space 41 from the boundary B of the communication space 5 be able to.
In addition, it has the same operation effect as Embodiment 1.

  As shown in FIG. 13, both of the two projecting portions 8 may be disposed on one side of the central axis of the high pressure tower 23 in the longitudinal direction Y. That is, the two protrusions 8 may be disposed on one side in the vertical direction of the alternate long and short dash line shown in FIG. At this time, it is preferable that the boundary portion B of the communication space 5 is also formed at a position where the projecting portion 8 is formed on the periphery thereof.

  Further, as shown in FIG. 14, even when the projecting direction of the flange 24 in the case 2 is orthogonal to the projecting direction of the connector 25 in the case 2, the projecting portion 8 is aligned with the center axis of the high pressure tower 23 and the flange 24. In the flange 24 side of the central axis of the high pressure tower 23. Here, in FIG. 14, a straight line passing through the central axis of the high pressure tower 23 and extending in a direction orthogonal to the alignment direction of the central axis of the high pressure tower 23 and the flange 24 is indicated by a dashed dotted line. That is, the protrusion 8 is formed closer to the flange 24 than the alternate long and short dash line in FIG. Also in the case shown in FIG. 14, the boundary portion B is formed on the flange 24 side of the central axis of the high pressure tower 23 and when viewed from the axial direction Z, the central axis of the high pressure tower 23 and the bolt insertion It is preferable to arrange on a straight line connecting with the central axis of the hole 241 (that is, a two-dot chain line in FIG. 14). Thus, when attaching the ignition coil 1 to the internal combustion engine, the axial force of the bolt 108 inserted into the bolt insertion hole 241 of the flange 24 is easily transmitted to the projecting portion 8. Therefore, the projecting portion 8 is easily elastically deformed, and in the state of being attached to the internal combustion engine, the communication space 5 is easily closed.

  Further, as shown in FIG. 15, even when the projecting direction of the flange 24 in the case 2 is inclined with respect to the projecting direction of the connector 25 in the case 2, the projecting portion 8 can be the central axis of the high pressure tower 23 and the flange It can be formed on the side of the flange 24 with respect to the central axis of the high pressure tower 23 in the direction of alignment with the side 24. Here, in FIG. 15, a straight line passing through the central axis of the high pressure tower 23 and extending in a direction orthogonal to the alignment direction of the central axis of the high pressure tower 23 and the flange 24 is indicated by a dashed dotted line. That is, the protrusion 8 is formed closer to the flange 24 than the alternate long and short dash line in FIG. Also in the case shown in FIG. 15, the boundary portion B is formed on the flange 24 side of the central axis of the high pressure tower 23, and viewed from the axial direction Z, the central axis of the high pressure tower 23 and the bolt insertion It is preferable to arrange on a straight line connecting with the central axis of the hole 241 (that is, a two-dot chain line in FIG. 15). Thus, when attaching the ignition coil 1 to the internal combustion engine, the axial force of the bolt 108 inserted into the bolt insertion hole 241 of the flange 24 is easily transmitted to the projecting portion 8. Therefore, the projecting portion 8 is easily elastically deformed, and in the state of being attached to the internal combustion engine, the communication space 5 is easily closed.

  In the present embodiment, the length of the upper slide space 62 in the axial direction Z and the length of the lower slide space 61 are each formed equal to or longer than the length of the bottom wall side space 51 in the axial direction Z Although indicated, it is not limited to this. For example, each of the length of the upper slide space 62 in the axial direction Z and the length of the lower slide space 61 may be shorter than the length of the bottom wall side space 51 in the axial direction Z. In this case, when the ignition coil 1 is assembled to the internal combustion engine, the upper slide space 62 disappears due to the lower surface 231a of the tower upper portion 231 and the third opposing surface 313 of the joint 3 coming into contact with each other. , And a state in which the lower slide space 61 disappears when the retaining portion 232a of the high pressure tower 23 and the joint 3 abut in the axial direction Z. However, by further screwing the bolt 108 from this state, the axial force of the bolt 108 is transmitted in the axial direction Z from the case 2 to the joint. Since the joint 3 is elastically deformed by this, the case 2 can be further moved downward, and the bottom wall side space 51 can be contracted.

(Embodiment 3)
The present embodiment is an embodiment in which the shape of the projecting portion 8 is changed with respect to the second embodiment as shown in FIG. 16 and FIG. The protrusion 8 has a C shape that opens toward the center of the joint 3 when viewed in the axial direction Z.

Further, in the present embodiment, an upper groove 32 c which is a part of the space forming groove 32 constituting the communication space 5 is also formed on the first opposing surface 311 of the joint upper end portion 31. As shown in FIG. 16, the upper groove 32 c of the space forming groove 32 formed in the first opposing surface 311 is continuous from the opening side of the protrusion 8 to the inside of the protrusion 8 when viewed from the axial direction Z It is formed. Along with this, the boundary B of the communication space 5 is also formed continuously from the opening side of the protrusion 8 to the inside of the protrusion 8 when viewed in the axial direction Z. Then, at least a part of the boundary portion B is located inside the C-shaped protrusion 8.
Others are the same as in the second embodiment.

In the present embodiment, at least a part of the boundary portion B of the communication space 5 is located inside the C-shaped projecting portion 8, the bottom wall from the outside space 42 of the high pressure tower 23 and the joint 3 should be Even when foreign matter intrudes into the side space 51, the foreign matter can be further prevented from entering the high pressure tower 23 and the inner space 41 of the joint 3 from the boundary portion B of the communication space 5.
In addition, the same effects as those of the second embodiment are obtained.

(Embodiment 4)
The present embodiment is an embodiment in which positioning means in the circumferential direction between the case 2 and the joint 3 is provided to the second embodiment as shown in FIG. 18 to FIG. As shown in FIGS. 18 to 20, the joint upper end portion 31 has an engagement convex portion 33 projecting toward the case bottom wall 21 side. Further, as shown in FIGS. 18 and 21, the case bottom wall 21 has an engagement recess 234 that engages with the engagement protrusion 33. As shown in FIG. 18, circumferential positioning between the case 2 and the joint 3 is performed by the engagement convex portion 33 and the engagement concave portion 234.

  As shown in FIGS. 18 to 20, the engagement convex portion 33 is extended upward from the first opposing surface 311 of the joint upper end portion 31. The engagement convex portion 33 has a substantially cylindrical shape. As shown in FIGS. 18 and 21, the engagement recess 234 is formed such that a portion of the bottom wall lower surface 211 of the case bottom wall 21 is recessed upward. In the present embodiment, the length of the engagement recess 234 in the axial direction Z is larger than the length of the engagement protrusion 33 in the axial direction Z. Thus, even when the ignition coil 1 is fastened to the internal combustion engine and the first opposing surface 311 of the joint upper end 31 and the bottom wall lower surface 211 of the case bottom wall 21 are in surface contact, the engagement convex portion in the axial direction Z A gap is formed between 33 and the engagement recess 234.

As shown in FIG. 18, the engagement convex portion 33 and the engagement concave portion 234 are formed on one side in the longitudinal direction Y with respect to the central axis of the joint 3. As shown in FIG. 20, in the circumferential direction of the joint 3, the engagement convex portion 33 is formed at a position 90 ° away from the position where the projection 8 is formed. Along with this, the engagement recess 234 is also disposed at a position 90 ° apart from the position where the projection 8 is formed in the circumferential direction of the joint 3. However, the formation positions of the engagement convex portion 33 and the engagement concave portion 234 are not limited to those shown in the present embodiment.
Others are the same as in the second embodiment.

In the present embodiment, positioning of the joint 3 and the case 2 in the circumferential direction of the joint 3 can be facilitated. Thus, for example, when it is desired to form the position of the projecting portion 8 formed on the joint upper end portion 31 on the side close to the flange 24, assemble the joint 3 and the case 2 so that the projecting portion 8 is disposed in the vicinity of the flange 24. Can. Further, for example, in the case where the protrusion 8 is formed on the case bottom wall 21, the joint 3 and the case 2 can be easily assembled such that the protrusion 8 is disposed around the boundary B of the communication space 5.
In addition, the same effects as those of the second embodiment are obtained.

Embodiment 5
In the present embodiment, as shown in FIGS. 22 to 28, the case bottom wall 21 is formed with a housing recess 235 that abuts against the projecting portion 8 in the axial direction Z. The protrusion 8 is configured to be accommodated in the accommodation recess 235 in a state where the ignition coil 1 is attached to the internal combustion engine. As described later, in the present embodiment, in the state where the ignition coil 1 is attached to the internal combustion engine, the protrusion 8 is elastically deformed by the axial force of the bolt 108 and is press-fit into the housing recess 235, The protrusion 8 is housed in the housing recess 235.

  As shown in FIG. 24, when viewed in the axial direction Z, the accommodation recess 235 is formed in an arc shape that is a part of an annular shape centered on the central axis of the high pressure tower 23. In the present embodiment, the housing recess 235 is formed at two places in the case bottom wall 21. The two accommodation recesses 235 have an arc shape that opens in the direction facing each other in the lateral direction X. And two accommodation recessed parts 235 are formed so that the high voltage tower 23 may be surrounded from the both sides of the cross direction X, when it sees from the axial direction Z. In addition, it is not restricted to this, For example, as shown in FIG. 29, the accommodation recessed part 235 can also be formed in the annular | circular shape centering on the central axis of the high pressure tower 23. FIG. In this case, the accommodation recess 235 is formed such that the high pressure tower 23 is disposed inside thereof. That is, in this case, the accommodation recess 235 is formed to surround the high pressure tower 23 from the entire circumference when viewed in the axial direction Z. For convenience, in FIG. 29, the housing recess 235 is hatched.

  In the present embodiment, as shown in FIG. 22, FIG. 23, and FIG. 25, the projecting portion 8 of the joint upper end portion 31 is formed in a cylindrical shape. The projecting portion 8 is formed at a position overlapping in the axial direction Z with a part of the accommodation recess 235 of the case bottom wall 21. As shown in FIG. 23, the projecting portion 8 is formed with an easily press-in recess 81 which is recessed in the axial direction Z from the end face on the projecting side. Note that, except for FIG. 23 and FIG. 28 described later, the easy press-in recess 81 is omitted as appropriate.

  As shown in FIG. 23, the radial size of the protrusion 8 is larger than the radial size of the accommodation recess 235. That is, in the cross section parallel to the axial direction Z, the length L1 of the protrusion 8 in the direction orthogonal to the axial direction Z is smaller than the length L2 of the accommodation recess 235 in the direction orthogonal to the axial direction Z. Thus, the upper end portion of the protrusion 8 is in contact with the peripheral portion of the accommodation recess 235 in the case bottom wall 21. Further, in the present embodiment, the length L 3 of the protrusion 8 in the axial direction Z is smaller than the length L 4 of the accommodation recess 235 in the axial direction Z.

  Tapered surfaces 82 and 235 a are formed on the corner on the protruding side of the protrusion 8 and the corner on the opening side of the accommodation recess 235. A tapered surface 82 is formed such that the diameter of the protrusion 8 decreases toward the upper side at the corner of the peripheral edge on the protrusion side of the protrusion 8. Further, on the inner peripheral side and the outer peripheral side of the opening side of the housing concave portion 235, tapered surfaces 235a are formed such that both corner portions are inclined to be away from each other toward the lower side. The tapered surface 82 of the protrusion 8 and the tapered surface 235 a of the housing recess 235 are locked to each other. Note that, except for FIG. 23 and FIG. 28 described later, illustration of the tapered surfaces 82 and 235 a is omitted as appropriate.

Next, how the ignition coil 1 in the present embodiment is attached to an internal combustion engine will be described with reference to FIGS.
As in the first embodiment, the ignition coil 1 is inserted into the plug hole 105 from the joint 3 side, and the upper end of the spark plug 13 is inserted into the lower end of the joint 3. Then, as in the first embodiment, the upper end of the spark plug 13 is inserted into the lower end of the joint 3 so that the ignition coil 1 faces the spark plug 13 and the joint upper end 31 is the upper end surface 106 a of the lip 106 of the engine head 101. Push in until it abuts on the.

  Then, the bolt 108 is inserted into the bush 242 of the flange 24 and the bolt 108 is screwed into the screw hole 107 a of the boss 107 until the head 108 a of the bolt 108 abuts on the upper surface of the flange 24. This state is shown in FIG. In this state, the axial force of the bolt 108 does not act on the ignition coil 1. Then, in this state, as shown in FIG. 26, the projecting portion 8 is in contact with the periphery of the accommodation recess 235 in the case bottom wall 21. Therefore, in the state shown in FIG. 26, the state in which the bottom wall side space 51 is formed is maintained.

  Then, the bolt 108 is further screwed into the boss 107 from the state of FIG. Thus, the axial force of the bolt 108 is transmitted to the case 2 of the ignition coil 1. Thereby, the case 2 moves downward so as to approach the joint 3. Here, as described above, since the joint upper end 31 is in contact with the lip 106, the downward movement of the joint 3 is limited even if the case 2 moves downward due to the axial force of the bolt 108. Be done. Therefore, as the bolt 108 is screwed into the boss 107, the protrusion 8 of the joint upper end 31 is pressed into the receiving recess 235 of the case bottom wall 21 while being elastically deformed. Thus, the bottom wall side space 51 contracts as the bolt 108 is screwed into the boss 107.

  Then, by screwing until the lower surface of the flange 24 of the case 2 abuts on the upper surface of the boss 107, as shown in FIG. 27 and FIG. Side space disappears. That is, in the present embodiment, the communication space 5 formed in the state before the ignition coil 1 is attached to the internal combustion engine is closed in the state in which the ignition coil 1 is attached to the internal combustion engine.

Next, how the ignition coil 1 is removed from the internal combustion engine will be described.
As in the first embodiment, the bolt 108 is first removed from the boss 107 and the flange 24. As a result, the axial force of the bolt 108 acting on the case 2 disappears. However, since the projection 8 is press-fit into the housing recess 235, the relative position in the axial direction Z between the case 2 and the joint 3 does not change even if the axial force of the bolt 108 acting on the case 2 disappears.

  Next, in order to move the ignition coil 1 upward with respect to the spark plug, a load is applied to the ignition coil 1 in the axial direction Z. Here, the housing recess 235 and the projection are set such that the load in the axial direction Z necessary to pull out the housing recess 235 from the projection 8 is smaller than the load in the axial direction Z necessary to pull out the joint 3 from the spark plug 13. The interference in the axial direction Z with the portion 8 and the interference in the direction orthogonal to the axial direction Z are set. Furthermore, the length in the axial direction Z of the protrusion 8 accommodated in the accommodation recess 235 is set shorter than the fitting length of the joint 3 in the axial direction Z with respect to the spark plug 13. Therefore, when a load is applied to the ignition coil 1 in the axial direction Z in order to move the ignition coil 1 upward with respect to the spark plug 13, the housing recess 235 is formed before the joint 3 is completely removed from the spark plug 13. Can be completely removed. As a result, the bottom wall side space 51 is formed again between the case bottom wall 21 and the joint upper end portion 31, whereby the communication space 5 and the outer space 42 are communicated.

Then, the ignition coil 1 is pulled out of the spark plug 13. At this time, since the inner space 41 expands as the ignition coil 1 is pulled out of the spark plug 13, external air flows into the inner space 41 via the communication space 5. As a result, when the ignition coil 1 is pulled out of the spark plug 13, the ignition coil 1 can be easily pulled out of the spark plug 13 without an excessive negative pressure in the inner space 41.
Others are the same as in the second embodiment.

  In the present embodiment, the protrusion 8 is formed on one of the case bottom wall 21 and the joint upper end 31, and the other is formed with the recess 8 that abuts against the protrusion 8 in the axial direction Z. The projection 8 is configured to be accommodated in the accommodation recess 235 in a state where the ignition coil 1 is attached to the internal combustion engine. That is, in the state where the ignition coil 1 is attached to the internal combustion engine, the protrusion 8 can be completely accommodated in the accommodation recess 235. Therefore, when the ignition coil 1 is attached to the internal combustion engine, the bottom wall side space 51 formed when the ignition coil 1 is not attached to the internal combustion engine can be completely eliminated. Therefore, when the ignition coil 1 is attached to the internal combustion engine, foreign matter can be prevented from entering the inner space 41 from the outer space 42 of the ignition coil 1 through the communication space 5.

  In addition, when viewed from the axial direction Z, the accommodation recess 235 is formed in an annular shape centered on the central axis of the high pressure tower 23 or in an arc shape that is a part of the annular ring. Therefore, even if the positioning of the joint 3 and the case 2 in the circumferential direction is not strictly made, the projecting portion 8 can be easily disposed at a position overlapping the accommodation recess 235 in the axial direction Z. Therefore, the productivity of the ignition coil 1 can be easily improved.

  Further, the projecting portion 8 is formed with an easily press-in recess 81 which is recessed in the axial direction Z from the end face on the projecting side. Therefore, it is possible to reduce the force required when the protrusion 8 is pressed into the receiving recess 235. This also makes it easy to improve the productivity of the ignition coil 1.

In addition, tapered surfaces 82 and 235 a are formed at the corner on the protruding side of the protrusion 8 and the corner on the opening side of the accommodation recess 235. Therefore, the protrusion 8 can be easily inserted into the accommodation recess 235. This also makes it easy to improve the productivity of the ignition coil 1.
In addition, the same effects as those of the second embodiment are obtained.

Embodiment 6
In this embodiment, as shown in FIGS. 30 to 33, a part of the communication space 5 is constituted by the inside of the space forming groove 233 formed in the case 2 while the basic configuration is the same as that of the first embodiment. is there.

A space forming groove 233 is continuously formed from the inner space 41 of the high pressure tower 23 and the joint 3 to the outer space 42 on the surface facing the joint 3 in the case 2. One end of the space forming groove 233 is formed to the X1 side end of the bottom wall lower surface 211 of the case bottom wall 21, and the other end of the space forming groove 233 is formed to the lower end of the tower lower portion 232 of the high pressure tower 23 ing. In the present embodiment, no space forming groove (see reference numeral 32 in FIG. 2) is formed in the joint 3.
Others are the same as in the first embodiment.

  Also in the present embodiment, the same effects as in the first embodiment are obtained.

Seventh Embodiment
The present embodiment is an embodiment in which the formation position of the protrusion 8 in the ignition coil 1 is changed with respect to the second embodiment as shown in FIG. In the present embodiment, the protrusion 8 is formed between the high pressure tower 23 and the joint 3 in the axial direction Z. That is, the protrusion 8 is formed at a position not adjacent to the bottom wall side space 51.

  As described above, the joint 3 has the third opposing surface 313 opposed in the axial direction Z to the lower surface 231 a of the tower upper portion 231. And the protrusion part 8 is formed so that a part of 3rd opposing surface 313 may protrude toward the tower upper part 231 side of the axial direction Z. As shown in FIG. The length of the protrusion 8 in the axial direction Z is preferably larger than the length of the bottom wall side space 51 in the axial direction Z.

The protrusion 8 is in contact with the lower surface 231 a of the tower upper portion 231. In the present embodiment, the protrusion is not formed on the first opposing surface 311 of the joint 3.
Others are the same as in the first embodiment.

  In the present embodiment, as shown in FIG. 35, in the state where the ignition coil 1 is attached to the internal combustion engine, the projecting portion 8 is compressed by receiving the axial force of the bolt 108 and extinguishes the bottom wall side space 51 or substantially It can be erased. Thus, in the state where the ignition coil 1 is attached to the internal combustion engine, foreign matter can be suppressed from entering the inner space 41 from the outer space 42 of the ignition coil 1 through the communication space 5.

Furthermore, in the present embodiment, by making the length of the protrusion 8 in the axial direction Z larger than the length of the bottom wall side space 51 in the axial direction Z, the bottom is not completely crushed. The wall side space 51 can be erased. Therefore, in the state where the ignition coil 1 is attached to the internal combustion engine, it is possible to further suppress the foreign matter from entering the inner space 41 from the outer space 42 of the ignition coil 1 through the communication space 5.
In addition, the same effects as those of the second embodiment are obtained.

(Embodiment 8)
In the present embodiment, as shown in FIG. 36, the method of positioning the axial direction Z of the case 2 and the joint 3 for forming the bottom wall side space 51 is different from the second embodiment. In the present embodiment, the outer peripheral surface 231 b of the tower upper portion 231 of the high pressure tower 23 is reduced in diameter toward the lower side. That is, in a cross section which passes through the central axis of the high pressure tower 23 and is parallel to the axial direction Z, the outer peripheral surface 231b of the tower upper portion 231 is inclined toward the inner periphery as it goes downward.

  Similarly, the fourth opposing surface 314 of the joint 3 opposed to the outer peripheral surface 231b of the tower upper portion 231 in the joint 3 is also reduced in diameter toward the lower side. That is, in a cross section which passes through the central axis of the high pressure tower 23 and is parallel to the axial direction Z, the fourth opposing surface 314 is inclined toward the inner circumferential side as it goes downward.

  The inner diameter of the upper end portion of the fourth opposing surface 314 is smaller than the outer diameter of the upper end portion of the outer peripheral surface 231 b of the tower upper portion 231. The inner diameter of the upper end portion of the fourth opposing surface 314 is formed to be equal to the outer diameter of a portion slightly lower than the upper end portion of the outer peripheral surface 231 b of the tower upper portion 231. Thereby, the bottom wall side space 51 is formed between the first opposing surface 311 of the joint 3 and the bottom wall lower surface 211 of the case bottom wall 21 in a state where the case 2 and the joint 3 are fitted.

In the present embodiment, when attaching the ignition coil 1 to the internal combustion engine, the bottom wall side space 51 is formed in a state where the axial force of the bolt 108 acts on the case 2. When the axial force of the bolt 108 acts on the case 2, the case 2 moves downward so as to approach the joint 3. At this time, the upper part 231 of the high pressure tower 23 elastically spreads the upper part of the joint 3 slightly and moves the case 2 downward so as to approach the joint 3. Along with this, as the bolt 108 is screwed into the boss 107, the bottom wall side space 51 contracts. Then, by screwing until the lower surface of the flange 24 of the case 2 abuts on the upper surface of the boss 107, as shown in FIG. 37, the bottom wall side space disappears or substantially disappears.
Others are the same as in the second embodiment.

Also in the present embodiment, in the state where the ignition coil 1 is attached to the internal combustion engine, the projecting portion 8 is compressed by receiving the axial force of the bolt 108, and the bottom wall side space 51 can be extinguished or substantially extinguished. Thus, in the state where the ignition coil 1 is attached to the internal combustion engine, foreign matter can be suppressed from entering the inner space 41 from the outer space 42 of the ignition coil 1 through the communication space 5.
In addition, the same effects as those of the second embodiment are obtained.

(Embodiment 9)
The present embodiment is an embodiment in which the configuration of the communication space 5 is changed with respect to the second embodiment as shown in FIGS.

  As shown in FIGS. 38, 39, and 41, in the present embodiment, the communication space 5 has a space inside the above-mentioned intermediate groove 32b and the lower groove 32a, and a space inside the below-mentioned through hole 311a. As shown in FIGS. 38 and 41, the through hole 311a is formed in a straight line so as to penetrate the joint upper end portion 31 in the radial direction. Thereby, the through hole 311a is connected to the intermediate groove 32b at the inner peripheral end as shown in FIGS. 38 and 39, and the outer peripheral end communicates with the outer space 42 as shown in FIGS. 38 and 40. . As shown in FIGS. 38 and 41, in the present embodiment, the through hole 311a is formed to penetrate the joint upper end portion 31 in the lateral direction X in the radial direction. The through hole 311 a has a circular cross section orthogonal to the longitudinal direction, but is not limited thereto. For example, the through hole 311 a may have an elliptical shape or the like which is short in the axial direction Z.

  As shown in FIG. 39, the through hole 311a is formed at the center of the joint upper end portion 31 in the axial direction Z and at the center of the intermediate groove 32b in the circumferential direction. As shown in FIG. 42, the through hole 311 a is formed on the flange 24 side (that is, the X1 side) with respect to the central axis of the high pressure tower 23. As shown in FIG. 41, the through hole 311a is located on a straight line (not shown) connecting the central axis of the high pressure tower 23 and the central axis of the bolt insertion hole 241 of the flange 24 when viewed in the axial direction Z. . Thereby, when attaching the ignition coil 1 to an internal combustion engine so that it may mention later, the axial force of the volt | bolt 108 inserted in the bolt insertion hole 241 of the flange 24 tends to be transmitted to the through-hole 311a. Therefore, the through hole 311 a is easily elastically deformed, and in the state of being attached to the internal combustion engine, the communication space 5 is easily closed.

  As shown in FIG. 41, in the present embodiment, the first opposing surface 311 of the joint upper end portion 31 is formed flat without having the protruding portion (see reference numeral 8 in FIG. 7 etc.) of the second embodiment. There is. Further, as shown in FIG. 38, the bottom wall lower surface 211 of the case 2 is also formed flat, and the first opposing surface 311 of the joint upper end 31 and the bottom wall lower surface 211 of the case 2 are in surface contact with each other.

Next, how the ignition coil 1 is attached to the internal combustion engine will be described using FIGS. 42 and 43. FIG.
As in the second embodiment, the ignition coil 1 is inserted into the plug hole 105 from the joint 3 side, and the upper end of the spark plug is inserted into the lower end of the joint 3. Then, as in the second embodiment, the ignition coil 1 is pushed toward the spark plug until the joint upper end 31 abuts on the upper end surface 106 a of the lip 106 of the engine head 101.

  Then, the bolt 108 is inserted into the bush 242 of the flange 24 and the bolt 108 is screwed into the screw hole 107 a of the boss 107 until the head 108 a of the bolt 108 abuts on the upper surface of the flange 24. This state is shown in FIG. In this state, the axial force of the bolt 108 does not act on the ignition coil 1. Therefore, in the state shown in FIG. 42, the through hole 311a exists in a free state where it is not elastically deformed.

  Then, the bolt 108 is further screwed into the boss 107 from the state of FIG. Thus, the axial force of the bolt 108 is transmitted to the case 2 of the ignition coil 1. Thereby, the case 2 moves downward so as to approach the joint 3. Here, as described above, since the joint upper end 31 is in contact with the lip 106, the downward movement of the joint 3 is limited even if the case 2 moves downward due to the axial force of the bolt 108. Be done. Therefore, as the bolt 108 is screwed into the boss 107, the joint upper end 31 sandwiched between the case 2 and the lip 106 is compressed in the axial direction Z. Along with this, as the bolt 108 is screwed into the boss 107, the through hole 311a is also compressed in the axial direction Z.

  Then, by screwing until the lower surface of the flange 24 of the case 2 abuts on the upper surface of the boss 107, as shown in FIG. 43, the through hole 311a is completely crushed and the space inside is completely eliminated, or the through hole 311a collapses almost completely and the space inside it disappears almost completely. That is, in the present embodiment, as shown in FIG. 42, in the state where the communication space 5 formed in the state before the ignition coil 1 is attached to the internal combustion engine is attached to the internal combustion engine, as shown in FIG. It is occluded.

Next, how the ignition coil 1 is removed from the internal combustion engine will be described.
As in the second embodiment, the bolt 108 is first removed from the boss 107 and the flange 24. As a result, the axial force of the bolt 108 acting on the case 2 disappears. As a result, the case 2 is pushed by the restoring force of the compressed joint upper end 31 and moves upward. Then, the joint upper end 31 which has been compressed is restored. As a result, the collapsed through hole 311 a of the joint upper end portion 31 is restored. Thus, the communication space 5 is formed again, and the communication space 5 and the outer space 42 are in communication with each other.

  Then, the ignition coil 1 is pulled out of the spark plug 13. At this time, since the inner space 41 expands as the ignition coil 1 is pulled out of the spark plug 13, external air flows into the inner space 41 via the communication space 5. As a result, when the ignition coil 1 is pulled out of the spark plug 13, the ignition coil 1 can be easily pulled out of the spark plug 13 without an excessive negative pressure in the inner space 41.

  Others are the same as in the second embodiment.

  In the present embodiment, the first opposing surface 311 of the joint upper end 31 and the bottom wall lower surface 211 of the case 2 are mutually flat and in surface contact with each other, and at least one of the communication spaces 5 in the joint upper end 31. A through hole 311a constituting a portion is formed. Therefore, in a state where the ignition coil 1 is attached to the internal combustion engine, the joint upper end 31 is crushed by the axial force of the bolt 108 and the like, and the through hole 311a can be completely crushed or almost completely crushed accordingly. . Thus, in the state where the ignition coil 1 is attached, foreign matter such as moisture or dust can be suppressed from entering the inner space 41 from the outer space 421 of the ignition coil 1 through the communication space 5. Thereby, it is easy to ensure the insulation of the inside and outside of the joint, and it is easy to prevent the corrosion of the ignition coil 1. Further, in a state in which the ignition coil 1 is not fastened to the internal combustion engine, the joint upper end 31 is not elastically deformed, so the presence of the through hole 311a is maintained, and the presence of the communication space 4 is maintained accordingly. Therefore, when the ignition coil 1 is pulled out of the spark plug 13, the ignition coil 1 can be easily pulled out of the spark plug 13 without the inner space 41 becoming excessively negative pressure.

Further, in the present embodiment, the through hole 311 a is located closer to the flange 24 than the central axis of the high pressure tower 23. Therefore, when attaching the ignition coil 1 to the internal combustion engine, the axial force of the bolt 108 inserted into the bolt insertion hole 241 of the flange 24 is easily transmitted to the through hole 311 a formed in the joint upper end 31. Therefore, it is easy to elastically deform the through hole 311 a by the axial force of the bolt 108 and to easily close the communication space 5 in a state of being attached to the internal combustion engine.
In addition, the same effects as those of the second embodiment are obtained.

(Embodiment 10)
The present embodiment is also an embodiment in which the configuration of the communication space 5 is changed with respect to the second embodiment, as shown in FIGS.

  As shown in FIG. 44, in the present embodiment, the communication space 5 is a bottom wall side space 51, a space inside the through hole 311a, a space inside the intermediate groove 32b, a space inside the lower groove 32a, and a tower described later. There is a space inside the recess 236. The configuration of the through hole 311 a is the same as that of the ninth embodiment.

  As shown in FIGS. 44 to 46 and 49, the intermediate groove 32b has an in-groove rib 35 projecting to the inner peripheral side. The in-groove rib 35 is formed from the bottom of the intermediate groove 32b to the fourth opposing surface 314 of the joint 3 so as to completely fill a part of the intermediate groove 32b in the longitudinal direction. As shown in FIG. 46, the in-groove rib 35 is formed entirely from one end to the other end of the intermediate groove 32b in the circumferential direction. The inner peripheral end face of the central portion 351 in the axial direction Z of the in-groove rib 35 is formed to be flush with the portion of the fourth opposing surface 314 of the joint 3 adjacent to the intermediate groove 32 b. As in the eighth embodiment, the fourth opposing surface 314 is a surface of the joint 3 that faces the outer peripheral surface 231 b of the tower upper portion 231. The both end portions 351b in the axial direction Z of the central portion 351 of the in-groove rib 35 have a shape in which the amount of projection decreases as the distance from the central portion 351 in the axial direction Z increases. That is, the surfaces of the both end portions 351 b are formed in a tapered shape toward the outer peripheral side in the radial direction as the distance from the central portion 351 increases.

  As shown in FIGS. 44, 46 and 49, the in-groove rib 35 is formed in the vicinity of the lower side of the portion of the intermediate groove 32b through which the through hole 311a passes. As shown in FIGS. 44 and 49, the in-groove rib 35 is formed at a portion of the intermediate groove 32b facing the outer peripheral surface 231b of the tower upper portion 231 of the high pressure tower 23.

  As shown in FIG. 44 and FIG. 49, on the outer peripheral surface 231b of the tower upper portion 231 of the high pressure tower 23, there is a tower concave portion 236 recessed on the inner peripheral side at a position facing in the radial direction at least the in-groove rib 35 of the joint 3. It is formed. As shown in FIG. 47, in the present embodiment, the tower recess 236 is formed over the entire circumference of the outer peripheral surface 231 b of the high pressure tower 23 tower upper portion 231. That is, the tower recess 236 is formed in an annular shape.

  As shown in FIG. 49, the length of the tower recess 236 in the axial direction Z is longer than the length of the central portion 351 of the in-groove rib 35 in the axial direction Z. The tower recess 236 is formed such that the central portion 351 of the in-groove rib 35 fits inside the both end positions in the axial direction Z. That is, the central portion 351 of the in-groove rib 35 is not in contact with the outer peripheral surface 231 b of the tower upper portion 231 of the high pressure tower 23. The space between the tower recess 236 and the in-groove rib 35 constitutes a part of the communication space 5. For convenience, in the space formed between the tower recess 236 and the in-groove rib 35, the upper side than the central portion 351 of the in-groove rib 35 is referred to as a first gap 501, and the lower side than the central portion 351 is It is called a gap 502. Further, in FIG. 49, a path through which air can flow is indicated by a dashed arrow.

  As shown in FIGS. 44 to 46, also in the present embodiment, the protruding portion 8 is formed on the first opposing surface 311 of the joint upper end portion 31. As shown in FIG. 45, in the present embodiment, four protrusions 8 are formed on the first opposing surface 311. Each of the protrusions 8 is formed in the radial direction in a straight manner and has a convex shape that can be elastically deformed in the axial direction Z. The four protrusions 8 are formed at intervals of 90 ° in the circumferential direction. Of the four protrusions 8, two protrusions 8 are located closer to the flange 24 (that is, the X1 side) than the central axis of the high pressure tower 23, and the other two are greater than the central axis of the high pressure tower 23. It is located on the anti-flange 24 side (ie, the X2 side). As shown in FIG. 44, also in the present embodiment, the upper end of the protrusion 8 is in contact with the bottom wall lower surface 211 of the case 2. Thus, the joint 3 and the case 2 are positioned in the axial direction Z, and the bottom wall side space 51 is formed between the case bottom wall 21 and the joint upper end 31.

Next, how the ignition coil 1 is attached to an internal combustion engine will be described with reference to FIGS.
As in the second embodiment, the ignition coil 1 is inserted into the plug hole 105 from the joint 3 side, and the upper end of the spark plug is inserted into the lower end of the joint 3. Then, as in the second embodiment, the ignition coil 1 is pushed toward the spark plug until the joint upper end 31 abuts on the upper end surface 106 a of the lip 106 of the engine head 101.

  Then, the bolt 108 is inserted into the bush 242 of the flange 24 and the bolt 108 is screwed into the screw hole 107 a of the boss 107 until the head 108 a of the bolt 108 abuts on the upper surface of the flange 24. This state is shown in FIG. 48 and FIG. In this state, the axial force of the bolt 108 does not act on the ignition coil 1. Therefore, in the state shown in FIG. 48, the protrusion 8 is not elastically deformed, and the state where the bottom wall side space 51 is formed is maintained. Further, as shown in FIG. 49, both the first gap 501 and the second gap 502 between the in-groove rib 35 and the tower recess 236 are formed.

  Subsequently, the bolt 108 is further screwed into the boss 107 from the state of FIG. 48 and FIG. Thus, the axial force of the bolt 108 is transmitted to the case 2 of the ignition coil 1. As a result, as shown in FIGS. 50 and 51, the case 2 is moved downward so as to approach the joint 3. Here, as described above, since the joint upper end 31 is in contact with the lip 106, the downward movement of the joint 3 is limited even if the case 2 moves downward due to the axial force of the bolt 108. Be done. Therefore, as the bolt 108 is screwed into the boss 107, the position in the axial direction Z of the in-groove rib 35 does not change, but the position of the tower recess 236 moves downward. Then, in a state in which the bolt 108 is screwed in until the lower surface of the flange 24 of the case 2 abuts on the upper surface of the boss 107, as shown in FIG. In the vicinity of the upper side of the tower recess 236 at Thus, when the ignition coil 1 is attached to the internal combustion engine, the first gap described above is closed, whereby the communication space is closed.

  Further, as in the second embodiment, as the bolt 108 is screwed into the boss 107, the projection 8 is elastically deformed so as to be compressed in the axial direction Z. Thereby, the bottom wall side space 51 is contracted as the bolt 108 is screwed into the boss 107, and the lower surface of the flange 24 of the case 2 is screwed until it abuts against the upper surface of the boss 107, as shown in FIG. The protrusion elastically deforms until the bottom wall side space disappears or substantially disappears as shown.

  Further, as in the ninth embodiment, as the bolt 108 is screwed into the boss 107, the joint upper end 31 sandwiched between the case 2 and the lip 106 is compressed in the axial direction Z. Along with this, as the bolt 108 is screwed into the boss 107, the through hole 311a is also compressed in the axial direction Z. Here, in the present embodiment, even if the lower surface of the flange 24 of the case 2 is screwed until it abuts on the upper surface of the boss 107, the through hole 311a is not completely crushed as shown in FIG. Space remains as it is. However, as described above, in the state where the ignition coil 1 is attached to the internal combustion engine, the communication space is closed by surface contact between the inner peripheral end surface of the in-groove rib 35 and the outer peripheral surface 231b of the tower upper portion 231. .

Next, how the ignition coil 1 is removed from the internal combustion engine will be described.
As in the second embodiment, the bolt 108 is first removed from the boss 107 and the flange 24. As a result, the axial force of the bolt 108 acting on the case 2 disappears. As a result, the case 2 is pushed by the restoring force of the compressed joint upper end 31 (including the projection 8) and moves upward. Thus, the position of the in-groove rib 35 in the axial direction Z does not change, but the tower recess 236 of the high-pressure tower 23 moves upward, and the in-groove rib 35 is disposed in the tower recess 236. As a result, the first gap 501 is formed again between the in-groove rib 35 and the tower recess 236, whereby the communication space is reformed. Therefore, when the ignition coil 1 is pulled out of the spark plug 13, the ignition coil 1 can be easily pulled out of the spark plug 13 without the inner space 41 becoming excessively negative pressure.
Others are the same as in the second embodiment.

  In the present embodiment, in the state where the ignition coil 1 is attached to the internal combustion engine, the communication space 5 is formed by pressure welding the in-groove rib 35 and the outer peripheral surface 231 b of the tower upper portion 231 of the high pressure tower 23 in the radial direction. It is occluded. Therefore, the communication space 5 can be closed without being affected by the axial force of the bolt 108. Therefore, the communication space 5 can be closed without strictly controlling the bolt 108.

  The present invention is not limited to the above embodiments, and can be applied to various embodiments without departing from the scope of the invention. For example, in the second embodiment and the like, it is also possible to adopt a configuration in which the protrusion is a separate member from the portion other than the protrusion in the joint and joined to the portion other than the protrusion in the joint.

  Moreover, in each said embodiment, although the joint was comprised by one member, it is not restricted to this, A joint can also be comprised combining a several member. For example, the joint is formed of a molded resin portion made of PPS (i.e. polyphenylene sulfide), PBT (i.e. polybutylene terephthalate), SPS (i.e. syndiotactic polystyrene) or the like, and a rubber portion made of rubber. Is also possible. In this case, for example, each of the portion connected to the high pressure tower and the portion connected to the spark plug may be constituted by a rubber portion, and these may be connected by a molded resin portion.

1 Ignition Coil for Internal Combustion Engine 2 Case 20 Case Body 21 Case Bottom Wall 23 High Pressure Tower 3 Joint 41 Inner Space 42 Outer Space 5 Communication Space

Claims (17)

A primary coil (11) and a secondary coil (12) magnetically coupled to each other;
A case body (20) accommodating the primary coil and the secondary coil, and a case (2) having a cylindrical high-pressure tower (23) projecting from a case bottom wall (21) of the case body;
And a cylindrical joint (3) fitted to the high pressure tower and the spark plug (13);
A communication space (5) is formed between the high pressure tower and the joint, which communicates the high pressure tower and the inner space (41) of the joint, and the high pressure tower and the outer space (42) of the joint. And an ignition coil (1) for an internal combustion engine.   The ignition coil for the internal combustion engine according to claim 1, wherein at least a part of the communication space is inside a space forming groove (32, 233) formed in at least one of the case and the joint.   The joint has a joint upper end (31) opposite to the case bottom wall and in the axial direction (Z), and the case bottom wall and the joint upper end are oppositely spaced in the axial direction. A bottom wall side space (51) adjacent to the outer space is formed between the case bottom wall and the joint upper end portion, and the bottom wall side space constitutes a part of the communication space. An ignition coil for an internal combustion engine according to claim 1 or 2.   The ignition coil for an internal combustion engine according to claim 3, wherein at least one of the case and the joint has a projecting portion (8) which protrudes in the axial direction toward the other side and abuts on the other side.   The ignition coil for an internal combustion engine according to claim 4, wherein at least one of the case bottom wall of the case and the joint upper end of the joint has the protrusion.   When the boundary between the bottom wall side space and a portion on the inner space side of the bottom wall side space in the communication space, which is a part of the communication space, is defined as a boundary portion (B), the protrusion The ignition coil for the internal combustion engine according to claim 5, wherein is formed around the boundary portion so as to suppress foreign matter from entering the inner space from the outer space via the boundary portion.   The ignition coil for an internal combustion engine according to any one of claims 4 to 6, wherein the protrusion is a convex line elastically deformable in an axial direction.   The projecting portion is formed on one of the case and the joint, and a receiving recess (235) axially contacting the projecting portion is formed on the other, and the projecting portion is the ignition coil. The ignition coil for an internal combustion engine according to any one of claims 4 to 7, configured to be accommodated in the accommodation recess when being attached to the internal combustion engine.   9. The internal combustion engine according to claim 8, wherein when viewed from the axial direction, the housing recess is formed in an annular shape centered on the central axis of the high pressure tower or in a circular arc shape which is a part of the annular shape. Ignition coil.   The ignition coil for an internal combustion engine according to claim 8 or 9, wherein the projecting portion is formed with an easily press-in recess (81) axially recessed from an end face on the projecting side.   The taper surface (82, 235a) is formed in at least one of the corner on the protrusion side of the protrusion and the corner on the opening side of the accommodation recess. Ignition coil for an internal combustion engine as described.   The case body has a flange (24) projecting in a direction orthogonal to the axial direction and fixed to the internal combustion engine, and the projecting portion is elastically deformable in the axial direction, and the axial direction The internal combustion engine according to any one of claims 4 to 11, which is located closer to the flange than the central axis in a direction in which the central axis of the high pressure tower and the flange are aligned when viewed from the Ignition coil.   In the case bottom wall and the joint upper end, one has an engagement projection (33) projecting toward the other, and the other has an engagement recess (234) engaged with the engagement projection. The ignition for an internal combustion engine according to any one of claims 4 to 12, wherein circumferential positioning between the case and the joint is performed by the engagement convex portion and the engagement concave portion. coil.   The ignition coil for an internal combustion engine according to any one of claims 4 to 13, wherein the projection is formed between the high pressure tower and the joint in the axial direction.   The ignition coil for an internal combustion engine according to claim 14, wherein the length of the protrusion in the axial direction is larger than the bottom wall side space in the axial direction.   The joint has a joint upper end (31) axially opposed to the case bottom wall, and a surface of the joint upper end facing the case bottom wall is a first opposing surface (311), the case bottom wall The first opposing surface and the bottom wall lower surface are in close contact with each other, and at least a part of the communication space is at the joint upper end portion The ignition coil for an internal combustion engine according to claim 1 or 2, which is inside the formed through hole (311a).   In the space forming groove, an in-groove rib (35) formed to fill a part in the longitudinal direction of the space forming groove is formed, and a portion radially opposed to the in-groove rib in the high pressure tower A tower recess (236) is formed on the inner peripheral side, and in a state before the ignition coil is attached to the internal combustion engine, the space between the in-groove rib and the tower recess is the At least a part of the communication space is configured, and in a state after the ignition coil is attached to the internal combustion engine, at least the communication space is in close contact with the in-groove rib and the high pressure tower in the radial direction. The ignition coil for an internal combustion engine according to claim 2, which is configured to partially close.

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