JP2012033553A - Ignition coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil which simultaneously enhances both waterproofness and draining performance.SOLUTION: An annular seal member 60 seals between a casing 10 and a plug hole 4, while securing a breathing channel 41 communicating with the plug hole 4. A head 14 arranged outside the plug hole 4 in the casing 10 has: an annular groove 30, formed in the casing 10, which is opened to an insertion part 12 inserted into the plug hole 4, and which engages with the annular seal member 60 on the same axis so as to form, between itself and the annular seal member 60, a breathing chamber 42 communicating with the breathing channel 41; a slit 43, formed on an outer peripheral wall 38 of the annular groove 30, which penetrates in the radial direction through the entire part of the axial direction extending from a portion adjacent to the breathing chamber 42 to an end face 38a on the insertion part 12 side so as to open the breathing chamber 42 to the atmosphere; and a cover 50 which covers the entire part in the axial direction of the slit 43 from the outer peripheral side, while securing an atmospheric open space 44 opened to the atmosphere between itself and the slit 43.

Description

  The present invention relates to an ignition coil that induces a voltage applied to a spark plug in a plug hole in an internal combustion engine by a transformer section.

  Conventionally, a casing is provided with an insertion portion that is inserted into a plug hole to connect the transformer portion to a spark plug, and a head portion that is disposed outside the plug hole to connect the transformer portion to an external device. Ignition coils are widely used.

  As a kind of such an ignition coil, Patent Document 1 discloses that an annular sealing member arranged along the circumferential direction of the plug hole is provided between the casing and the plug hole in a state where a breathing path communicating between the inside and outside of the plug hole is secured in a labyrinth shape. What has been sealed is disclosed. In such a configuration, since the inside of the plug hole is opened to the atmosphere outside the plug hole through the breathing path, it is possible to adjust the pressure change in the plug hole due to the temperature change accompanying the operation of the internal combustion engine. At the same time, when a vehicle equipped with an internal combustion engine is washed at high pressure or when negative pressure is generated in the plug hole due to the rapid cooling of the internal combustion engine, the labyrinth-like breathing path causes water outside the plug hole to enter the plug hole. It is possible to avoid reaching.

JP 2009-212142 A

  Now, in the casing of the ignition coil disclosed in Patent Document 1, the annular seal member is coaxially fitted to the annular groove that opens toward the insertion portion at the head, so that the annular groove and the annular seal member A plurality of passage portions constituting a respiratory path are formed therebetween. Among these passage portions, the outer peripheral side passage portion formed between the outer surface of the annular seal member and the outer peripheral wall of the annular groove is adjacent to the annular passage portion formed between the end surface of the annular seal member and the bottom surface in the annular groove. In addition, it extends from the adjacent portion and is opened to the atmosphere at the end portion on the insertion portion side. However, in order to ensure waterproofness, the outer peripheral side passage portion has an outer surface of the annular seal member and an outer peripheral wall of the annular groove in a substantially entire region in the axial direction from the adjacent portion to the annular passage portion to the end portion on the insertion portion side. Is closed in the radial direction. Therefore, when water outside the plug hole enters the annular passage portion from the outer peripheral passage portion, a water film sticks to the closed outer peripheral passage portion due to surface tension, and the annular passage is formed through the outer peripheral passage portion. There was a risk that it would be difficult to drain the intrusion water into the passage.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an ignition coil that improves both waterproofness and drainage performance.

  The invention according to claim 1 is an ignition coil that induces an applied voltage to a spark plug in a plug hole in an internal combustion engine by a transformer portion, and is inserted into the plug hole to connect the transformer portion to the spark plug. A casing having a head portion disposed outside the plug hole to connect the transformer portion to the external device, and a breathing passage disposed along the circumferential direction of the plug hole and communicating with the plug hole. An annular seal member that seals between the casing and the plug hole in a secured state, and the head portion opens toward the insertion portion, and is coaxially fitted to the annular seal member to communicate with the respiratory passage. An annular groove that forms a breathing chamber between the annular seal member and an outer peripheral wall of the annular groove that contacts the outer surface of the annular seal member; A slit that opens the breathing chamber to the atmosphere outside the plug hole by passing through the entire area in the axial direction from the position to the end surface on the insertion section side to the atmosphere outside the plug hole, and an air opening space that is opened to the atmosphere outside the plug hole And a cover that covers at least a portion adjacent to the breathing chamber from the outer peripheral side in the entire axial direction of the slit.

  According to the first aspect of the present invention, the breathing passage secured by the annular seal member that is arranged along the circumferential direction of the plug hole and seals between the casing and the plug hole is the annular groove and the annular seal member of the casing head. It communicates with the breathing chamber formed therebetween and the inside of the plug hole. Here, the slit penetrating the outer peripheral wall of the annular groove opens the adjacent breathing chamber to the atmosphere outside the plug hole, so that the plug hole is also opened to the atmosphere through the breathing chamber and the breathing passage. Therefore, it is possible to adjust the pressure change in the plug hole due to the temperature change accompanying the operation of the internal combustion engine.

  Further, the slit of the invention according to claim 1 is an annular groove in the casing head that opens toward the insertion portion inserted into the plug hole in the casing and in which the annular seal member fits coaxially. The outer peripheral wall which contacts the outer surface of the annular seal member penetrates in the radial direction. Here, at least the portion adjacent to the breathing chamber in the entire axial direction of the slit is covered with the cover from the outer peripheral side, so water from the outer peripheral side of the cover outside the plug hole is supplied to the respiratory chamber through the slit. Movement is less likely to occur. At the same time, the region where the slit penetrates in the radial direction on the outer peripheral wall of the annular groove is the entire axial direction from the adjacent portion to the breathing chamber to the end surface on the insertion portion side. An open space is secured between the cover and the cover. Thereby, the slit is not closed in the radial direction by the outer peripheral wall of the annular groove and the cover, and is in a state opened to the atmosphere outside the plug hole through the atmosphere opening space, so even if water outside the plug hole enters, It is difficult for the water film to stick due to the surface tension of the intrusion water. According to these actions, not only can the infiltration of water into the respiratory chamber be suppressed, but even the intrusion water into the respiratory chamber can be easily discharged through the open slit, so that the ingress water can be discharged into the respiratory chamber. It is possible to avoid the situation of sequentially reaching the breathing passage and the plug hole beyond the above.

  As described above, the invention according to claim 1 improves both waterproofness and drainage in the breathing path that connects the inside and outside of the plug hole by connecting the breathing passage, the breathing chamber, the slit, and the open air space. It can be done.

  According to the second and eighth aspects of the present invention, the annular seal member has a facing surface that faces the bottom surface in the annular groove from the insertion portion side with the breathing chamber interposed therebetween, and the slit is more than the facing surface. Adjacent to the respiratory chamber in the radial direction on the side opposite to the insertion portion side. According to this, in the slit that penetrates the outer peripheral wall of the annular groove in the radial direction, the location adjacent to the respiratory chamber in the radial direction is an annular shape facing the bottom surface in the annular groove from the insertion portion side with the respiratory chamber interposed therebetween. It will be in the state covered with the cover of the outer peripheral side on the opposite side to the insertion part side rather than the opposing surface of a sealing member. In such a state, the water on the outer peripheral side of the cover can be prevented from moving in the radial direction through the slit on the inner peripheral side of the cover to the breathing chamber in the region located on the opposite side of the insertion surface from the opposing surface. Therefore, it can contribute to the improvement of waterproofness.

  According to the third aspect of the present invention, the cover covers, from the outer peripheral side, a portion of the slit that straddles the insertion portion side and the opposite side of the facing surface. Thereby, in the slit, not only the location adjacent to the breathing chamber on the side opposite to the insertion portion side from the facing surface of the annular seal member, but also the location located on the insertion portion side from the facing surface, The cover is covered. In such a state, the water on the outer periphery side of the cover enters the slit on the inner periphery side of the cover on the insertion portion side from the opposing surface in addition to the radial movement to the respiratory chamber on the opposite side of the insertion surface from the opposing surface. Can also be hindered, which can greatly contribute to the improvement of waterproofness.

  According to invention of Claim 4, a cover covers the axial direction whole region of a slit from an outer peripheral side. Thereby, in the slit, not only the portion adjacent to the respiratory chamber but also the portion reaching the outer peripheral wall end surface of the annular groove closer to the insertion portion than the adjacent portion is covered with the cover. In such a state, the water on the outer peripheral side of the cover can be prevented from entering the slit in the arbitrary axial direction on the inner peripheral side of the cover, which can greatly contribute to the improvement of waterproofness.

  According to the invention of claim 5, the annular seal member is in a state in which a clearance to be opened to the atmosphere outside the plug hole is secured between the annular groove and the end surface on the insertion portion side where the slit opens in the outer peripheral wall of the annular groove. And a cover that covers the slit from the insertion portion side. As a result, the slit is not only covered from the outer peripheral side by the cover, but is also covered from the insertion part side by the cover part of the annular seal member, so that it is difficult for water to enter from the outside of the plug hole and the waterproofness is improved. obtain. In addition, a gap that is opened to the atmosphere outside the plug hole is secured between the annular groove outer peripheral wall and the cover on the insertion portion side end surface where the slit opens, so that the opening can be reliably released to the atmosphere even at the opening. In the slit, a decrease in drainage due to the sticking of the water film hardly occurs.

  According to the sixth aspect of the present invention, the annular seal member has a seal lip on the outer surface that protrudes in the radial direction and elastically contacts the outer peripheral wall of the annular groove on both sides sandwiching the slit in the circumferential direction. According to this, the seal lip projecting radially on the outer surface of the annular seal member makes elastic contact with the outer peripheral wall of the annular groove on both sides sandwiching the slit in the circumferential direction, thereby forming the slit and the annular seal member. It becomes the state which gives uneven | corrugated shape to a corner | angular part. Therefore, the water that has entered from the outside of the plug hole into the gap between the end surface on the outer peripheral wall of the annular groove and the cover portion of the annular seal member forms a corner formed by the slit that opens in the end surface on the insertion portion and the annular seal member. The movement to the respiratory chamber side can be hindered by the uneven shape of the corner. Therefore, it can contribute to the improvement of waterproofness.

  According to the invention described in claim 7, in the head portion of the casing in which the insertion portion is inserted into the plug hole inclined with respect to the vertical direction, the annular groove is inclined with respect to the vertical direction, and the slit is the annular groove. It is located in the lowermost part of the outer peripheral wall. According to this, in the head portion of the casing in which the annular groove is inclined with respect to the vertical direction together with the plug hole into which the insertion portion is inserted, the outer peripheral side of the outer circumferential wall of the annular groove The downward intrusion of water can be accelerated by gravity. Therefore, it can contribute to the improvement of drainage.

  According to the eighth aspect of the invention, in addition to the configuration described above, the end surface on the insertion portion side of the outer peripheral wall of the annular groove is positioned below the opposing surface of the annular seal member that defines the breathing chamber. Thus, in the slit extending from the adjacent portion of the breathing chamber to the end surface on the insertion portion side located below the facing surface of the annular seal member that defines the breathing chamber on the outer peripheral wall of the annular groove, water is discharged downward. The water movement toward the upper respiratory chamber can be suppressed. Therefore, both drainage and waterproofness can be improved.

It is sectional drawing which shows the state which mounted the ignition coil by one Embodiment of this invention in the internal combustion engine. It is a partial cross section front view which shows the ignition coil of FIG. It is a bottom view which shows the casing of FIG. It is sectional drawing which expands and shows the principal part of the ignition coil of FIG. It is a top view which shows the annular seal member of FIG. It is a perspective view which shows the principal part of the ignition coil of FIG. It is a schematic diagram for demonstrating the dimension setting of the ignition coil of FIG. It is sectional drawing which shows the modification of FIG. It is sectional drawing which shows another modification of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a state in which an ignition coil 1 according to an embodiment of the present invention is mounted on an internal combustion engine 2 of a vehicle. The ignition coil 1 applies a voltage induced by the transformer unit 100 to a spark plug 5 in a plug hole 4 provided in the cylinder head 3 of the internal combustion engine 2. Here, the ignition coil 1 of the present embodiment is a stick-type ignition coil in which a part of the transformer unit 100 is located in the plug hole 4 and the remaining part of the transformer unit 100 is located outside the plug hole 4. Further, the plug hole 4 of the present embodiment is formed in a cylindrical hole shape in which the axial direction is inclined at a predetermined angle θ such as 35 degrees with respect to a vertical direction (vertical direction of the paper surface of FIG. 1) in a vehicle on a horizontal plane. The axial direction of the stick ignition coil 1 as a whole inserted into the plug hole 4 is also inclined at substantially the same angle θ with respect to the vertical direction.

(Basic configuration)
Hereinafter, the basic configuration of the ignition coil 1 will be described. The ignition coil 1 includes a casing 10, an annular seal member 60, and a transformer unit 100.

  As shown in FIGS. 1 and 2, the insertion portion 12 serving as a portion inserted into the plug hole 4 in the casing 10 has a cylindrical shape as a whole, and a rubber plug at the lower end in the axial direction of the resin casing body 20. The cap 21 is connected via a resin tower 22. As shown in FIG. 1, the spark plug 5 screwed into the plug hole 4 is press-fitted into the plug cap 21 so that the plug 5 and the transformer unit 100 can be connected.

  The head portion 14 which is a portion disposed outside the plug hole 4 in the casing 10 has a cylindrical shape larger in diameter than the insertion portion 12 as a whole, and from two circumferential positions of the axial upper end portion of the casing body 20, Each of the resin connector 23 and the metal flange 24 protrudes in the radial direction (see FIGS. 2 and 3). By connecting a cable connected to a predetermined external device to the connector 23, the external device and the transformer unit 100 can be connected. Also, the ignition coil 1 can be fixed to the internal combustion engine 2 by screwing the flange 24 to the fixing portion 7 of the cylinder head 3.

  As shown in FIGS. 1 and 2, the rubber annular seal member 60 has a thick annular plate shape or a cylindrical shape as a whole, and the insertion portion 12 and the head portion 14 of the casing body 20 of the casing 10 are arranged. It is interposed between the straddling axial intermediate portion and the opening of the plug hole 4. The annular seal member 60 is provided with a mounting groove 68 that opens toward the insertion portion 12 side (plug hole 4 side) and extends in the circumferential direction. As shown in FIG. 1, the mounting groove 68 is fitted and mounted to the annular protrusion 6 provided in the opening of the plug hole 4 in the cylinder head 3, so that the annular seal member 60 is connected to the plug hole. 4 are arranged along the circumferential direction. In such an arrangement state, the annular seal member 60 hermetically and liquid-tightly seals between the casing 10 and the plug hole 4 in a state in which the breathing path 40 communicating with the inside and outside of the plug hole is secured.

  As shown in FIG. 1, the transformer unit 100 included in the casing 10 includes coils 101 and 102, spools 103 and 104, a central core 105, an outer core 106, an external connection terminal 107, an igniter 108, a high voltage terminal 109, and a conductive spring. 110 or the like.

  The primary coil 101 is formed by winding a primary conductor such as an enameled wire with an insulating coating around an outer peripheral portion of a primary spool 103 made of resin. The primary coil 101 is fixed in the casing body 20 via the primary spool 103. The secondary coil 102 is coated with an insulating coating and has a secondary conductor such as an enameled wire that is thinner than the primary conductor of the primary coil 101 on the outer periphery of the secondary spool 104 made of resin with a greater number of turns than the primary conductor. It is wound. The secondary coil 102 together with the secondary spool 104 is disposed on the inner peripheral side of the primary coil 101 and the primary spool 103, and is fixed in the casing body 20 via the secondary spool 104.

  A central core 105 made of a soft magnetic material is formed in the shape of a longitudinal bar, and is disposed on the inner peripheral side of the secondary spool 104 and is fixed in the casing body 20. An outer core 106 made of a soft magnetic material is formed in a long sleeve shape, is arranged on the outer periphery side of the primary coil 101, and is fixed in the casing body 20.

  A plurality of metal external connection terminals 107 are embedded in the connector 23 so that the coils 101 and 102 and the igniter 108 can be connected to an external power source and a control circuit as an external device through a cable connected to the connector 23, respectively. Yes. The igniter 108 is an electronic circuit that is connected to the primary coil 101 and switches the energization and shutoff timing of the primary coil 101 in accordance with an input signal from the control circuit through the external connection terminal 107. It is fixed to. The metal high-voltage terminal 109 is connected to the secondary coil 102, and is fixed to the lower end in the axial direction of the casing body 20 at the insertion portion 12. The high voltage terminal 109 can be connected to the spark plug 5 in the plug cap 21 through a metal conductive spring 110 disposed in the tower portion 22.

  In the ignition coil 1 having such a configuration, when the energizing current from the external power source to the primary coil 101 is interrupted by the igniter 108 in accordance with the input signal from the control circuit, the mutual induction action between the primary coil 101 and the secondary coil 102 is caused. For example, a high voltage such as 30 to 40 kV is generated in the secondary coil 102. The high voltage generated in the secondary coil 102 in this manner is applied to the spark plug 5 through the high voltage terminal 109 and the conductive spring 110, thereby generating a spark discharge at the tip of the plug 5.

(Feature configuration)
Next, a characteristic configuration of the ignition coil 1 will be described. As shown in FIG. 3, the head 14 has an annular groove 30, a slit 43, and a cover 50. In the following description, the “insertion portion 12 side” and the “opposite side of the insertion portion 12” in the axial direction of the head 14 are abbreviated as “insertion portion side” and “counterinsertion portion side”, respectively.

  As shown in FIGS. 3 and 4, the annular groove 30 extends in the circumferential direction so as to open toward the insertion portion in the head 14, and the axial direction of the groove 30 with respect to the vertical direction is a plug hole. 4 is inclined at substantially the same angle θ (see FIG. 1). The annular groove 30 of this embodiment includes a fitting recess 31, passage recesses 32 and 33, a partition recess 34, a connection recess 35, and the like.

  The fitting recess 31 includes an annular hole-shaped large-diameter recess 36 that is recessed from the axial lower end surface 14 a of the head 14 toward the anti-insertion portion, and an anti-insertion portion from the inner peripheral side edge of the bottom surface of the large-diameter recess 36. An annular hole-shaped small-diameter concave portion 37 that is recessed toward the side is provided coaxially with respect to the head portion 14. As shown in FIG. 4, the intermediate portion 61 is coaxially fitted in the large-diameter recess 36 in the axial direction of the annular seal member 60. Here, particularly in the present embodiment, the upper surface 61 b of the intermediate portion 61 is in surface contact with the bottom surface 36 a of the large-diameter recess 36. In the present embodiment, the outer surface 61a of the intermediate portion 61 is provided with a plurality of annular lip-shaped (see FIG. 5) seal lips 64 that protrude in the radial direction and extend in the circumferential direction. 64 is press-fitted into the outer peripheral wall 38 of the annular groove 30 forming the outer peripheral side surface of the large-diameter recess 36. Accordingly, each seal lip 64 is in elastic contact with the outer peripheral wall 38 of the annular groove 30.

  On the other hand, in the small-diameter concave portion 37, an axial upper end portion 62 that protrudes from the intermediate portion 61 to the side opposite to the insertion portion in the annular seal member 60 is fitted coaxially. In the annular seal member 60 in which the upper end 62 is fitted into the small-diameter concave portion 37 in this way, the lower end portion 63 in the axial direction is closer to the insertion portion than the large-diameter concave portion 36 into which the intermediate portion 61 is fitted. It protrudes to the outer peripheral side (see FIG. 5). Particularly in this embodiment, the outer diameter of the lower end 63 of the annular seal member 60 is set to be substantially the same as the outer diameter of the outer peripheral wall 38 of the annular groove 30. Thus, the annular seal member 60 secures a gap 48 that is open to the atmosphere outside the plug hole 4 between the outer peripheral portion 66 of the lower end portion 63 and the insertion portion side lower end surface 38a of the outer peripheral wall 38.

  As shown in FIGS. 3 and 4, the linear groove-shaped inner passage recess 32 is recessed in the radial direction from the inner peripheral side surfaces of the large-diameter recess 36 and the small-diameter recess 37 and extends from the head 14 to the insertion portion 12. Thus, the outer surface of the insertion portion 12 is also recessed in the radial direction. The L-shaped groove-shaped outer passage recess 33 extends in the axial direction so as to be recessed in the radial direction from the outer peripheral side surface facing the inner passage recess 32 in the small-diameter recess 37, and further from the bottom surface of the large-diameter recess 36 to the non-insertion portion side. Bent in the radial direction in a concave shape. Each passage recess 32, 33 of the present embodiment is provided at a position corresponding to the uppermost portion 37a of the small-diameter recess 37 inclined with respect to the vertical direction. The small-diameter concave portion 37 of the fitting concave portion 31 together with the passage concave portions 32 and 33 is an annular seal member that fits in the concave portion 31 with the respiratory passage 41 that communicates with the plug hole 4 and forms a part of the respiratory passage 40. A partition is formed between 60 and 60.

  A plurality of partitioning recesses 34 are provided in a form that is recessed toward the side opposite to the insertion portion from a position spaced apart at a predetermined interval in the circumferential direction at the outer peripheral side edge of the bottom surface 36a of the large-diameter recess 36. Each partitioning recess 34 is formed in a circular arc shape along the outer peripheral wall 38 of the annular groove 30 on the outer peripheral side surface. In addition, an outer passage recess 33 is opened on the inner peripheral side surface of the partition recess 34 at a position corresponding to the uppermost portion 37 a of the radial recess 37. A plurality of connection recesses 35 are provided in a form that is recessed toward the side opposite to the insertion portion from a portion between the respective partition recesses 34 in the circumferential direction at the outer peripheral side edge of the bottom surface 36 a of the large-diameter recess 36. Each connection recess 35 connects the partition recesses 34 by forming the outer peripheral side surface in the shape of an arc hole along the outer peripheral wall 38 of the annular groove 30. About each connection recessed part 35 of this embodiment, the amount of depressions to the anti-insertion part side is set smaller than any partition recessed part 34.

  Such partition recesses 34 and connection recesses 35 form a partition between the breathing chamber 42 communicating with the breathing passage 41 and forming a part of the breathing path 40 with the annular seal member 60 fitted into the fitting recess 31. is doing. Thereby, in the annular seal member 60, the upper surface 61b of the intermediate portion 61 is in the respiratory chamber 42 with respect to the bottom surface 34a of each partitioning recess 34 and the bottom surface 35a of each connection recess 35 among the bottom surfaces in the annular groove 30 shown in FIG. It becomes the opposing surface 61b which opposes from the insertion part side on both sides of.

  In the annular groove 30 inclined with respect to the vertical direction, the slit 43 penetrates the lowermost portion 38d in the radial direction in the outer peripheral wall 38 with which the annular seal member 60 comes into contact with the seal lip 64 of the outer surface 61a. Here, the region where the slit 43 penetrates in the radial direction in the outer peripheral wall 38 of the annular groove 30 is in the radial direction with the respiratory chamber 42 on the side opposite to the insertion surface 61b of the annular seal member 60 defining the respiratory chamber 42. Is set over the entire area in the axial direction from the portion adjacent to to the insertion portion side lower end surface 38a.

  As shown in FIGS. 3 and 4, the linear slit 43 extending along the axial direction of the annular groove 30 with such a configuration includes the lower end surface 38 a of the outer peripheral wall 38 positioned below the facing surface 61 b, and the recess 36. , 34, 35 open to the inner surface 38 b of the outer peripheral wall 38 and the outer surface 38 c of the outer peripheral wall 38. Therefore, as shown in FIG. 4, the outer peripheral portion 66 of the lower end portion 63 of the annular seal member 60 is a cover portion 66 that covers the opening portion of the slit 43 in the lower end surface 38 a from the insertion portion side with the gap 48 interposed therebetween. ing. 4 and 6, the seal lip 64 of the outer surface 61a of the annular seal member 60 is in elastic contact with both side portions sandwiching the opening of the slit 43 in the circumferential direction on the inner surface 38b, and the slit from the opening. In 43, a part of the meat is slightly plunged.

  As shown in FIGS. 3 and 4, the cover 50 is formed in a substantially rectangular cylindrical shape by integral resin molding with the outer peripheral wall 38 of the annular groove 30. The cover 50 projects in the radial direction from both side portions of the outer peripheral wall 38 that sandwich the opening portion of the slit 43 in the circumferential direction on the outer surface 38c, and a portion that is spaced from the opening portion to the side opposite to the insertion portion. The outer peripheral side of the slit 43 is covered by the connection between the overhanging portions. Here, in particular, the cover 50 of the present embodiment has a lower end surface 50a that opens toward the insertion portion side that is continuous with the lower end surface 38a of the outer peripheral wall 38 in the radial direction, so that the entire axial direction of the slit 43 can be seen from the outer peripheral side. It is in the form of covering. In other words, the slit 43 is surrounded by the cover 50 at a location adjacent to the breathing chamber 42 on the side opposite to the insertion portion from the facing surface 61b of the annular seal member 60 and a location on the insertion portion side from the facing surface 61b. Covered from the side.

  With the above configuration, the cover 50 secures a space 44 between the slit 43 and the entire area in the axial direction, and opens the space 44 to the atmosphere outside the plug hole 4 from the opening 50b in the lower end surface 50a on the insertion portion side. ing. In addition, since such an atmosphere open space 44 communicates with the entire axial direction of the slit 43, the breathing chamber 42 adjacent to the slit 43 is also opened to the atmosphere outside the plug hole 4. Accordingly, in the ignition coil 1, the breathing path 40 is secured by the connection of the breathing passage 41, the breathing chamber 42, the slit 43, and the open air space 44, and the plug hole 4 resulting from the temperature change accompanying the operation of the internal combustion engine 2. The internal pressure change can be adjusted through the path 40.

  In the present embodiment, the sizes of the slit 43, the open air space 44, and the gap 48 can be set as appropriate. For example, the slit 43 has an outer peripheral wall 38 of the annular groove 30 as shown in FIG. It is desirable to set the size SL in the circumferential direction of 1 mm or more. Further, as shown in FIG. 7B, the size SP in the radial direction of the outer peripheral wall 38 of the annular groove 30 is desirably set to 2 mm or more for the atmosphere open space 44 on the inner peripheral side of the cover 50. Furthermore, for the gap 48, as shown in FIG. 7B, it is desirable to set the size OP in the axial direction of the outer peripheral wall 38 of the annular groove 30 to 0.5 mm or more.

  According to the ignition coil 1 described so far, the slit 43 that penetrates the outer peripheral wall 38 of the annular groove 30 in the radial direction to form the breathing path 40 is formed from the outer peripheral side by the cover 50 that opens only on the insertion portion side. Covered. Here, the slit 43 is located on the side opposite to the insertion portion from the facing surface 61b of the annular seal member 60, and the axial location adjacent to the respiratory chamber 42 in the radial direction is also lower on the insertion portion side than the facing surface 61b. All the axial positions reaching the end surface 38a are also covered by the cover 50. Therefore, the water outside the plug hole 4 not only prevents the slit 43 on the cover inner periphery side from entering the entire area in the axial direction but also covers the cover outer periphery side in the region opposite to the insertion surface side than the facing surface 61b. To the respiratory chamber 42 through the slit 43 is also prevented. According to such an action of suppressing the ingress and movement of water, the slit in the breathing path 40 can be used even when the vehicle is subjected to high-pressure washing or when the negative pressure is generated in the plug hole 4 due to the rapid cooling of the internal combustion engine 2. Infiltration of water from 43 into the respiratory chamber 42 can be suppressed. Therefore, it is possible to avoid a situation in which water outside the plug hole 4 sequentially reaches the breathing passage 41 and the plug hole 4 from the slit 43 side through the breathing chamber 42.

  Furthermore, according to the ignition coil 1, an open air space 44 that is open to the atmosphere through the opening 50 b on the insertion portion side of the cover 50 is secured between the entire axial direction of the slit 43 and the cover 50 on the outer peripheral side. ing. As a result, the slit 43 is not closed in the radial direction by the outer peripheral wall 38 of the annular groove 30 and the cover 50 and is in an open state to the atmosphere, so that even if water outside the plug hole 4 enters, It is difficult to stick as a water film due to a large direction-dependent bias in the surface tension. For this reason, according to the slit 43 in the open state, even water that has entered the respiratory chamber 42 can be easily discharged.

  Furthermore, according to the ignition coil 1, the slit 43 is not only covered from the outer peripheral side by the cover 50, but is also covered from the insertion part side by the cover part 66 of the annular seal member 60, so that it bounced off by the cylinder head 3. Water splash is difficult to enter from the insertion side. In addition, since the gap 48 in the air release state can be secured between the lower end surface 38a where the slit 43 opens in the outer peripheral wall 38 of the annular groove 30 and the cover 66 that exerts such an action, the above-described gap is obtained. The water film sticking suppressing action is not hindered by the cover 66.

  In addition, according to the ignition coil 1, the slit 43 is not only located at the lowermost part 38 d of the outer peripheral wall 38 of the annular groove 30, but also has an annular shape that defines the respiratory chamber 42 from a location adjacent to the respiratory chamber 42. The seal member 60 extends to the lower end surface 38a below the facing surface 61b. In such a slit 43, even if the splash of water bounced off by the cylinder head 3 enters from the insertion portion side opening 50b or the like below the cover, the intrusion water is subjected to a gravitational action, thereby facilitating the downward discharge. Thus, the movement toward the upper respiratory chamber 42 side is suppressed.

  In addition, according to the ignition coil 1, the plurality of seal lips 64 projecting radially on the outer surface 61a of the annular seal member 60 are in elastic contact with the outer peripheral wall 38 of the annular groove 30 on both sides of the slit 43 in the circumferential direction. In the slit 43, a part of the meat is in a state of entering. In this state, as shown in FIG. 6, each seal lip 64 gives an uneven shape to the corner 90 formed by the outer surface 61 a of the annular seal member 60 and the slit 43. Therefore, even if water enters the gap 48 between the cover 66 of the annular seal member 60 and the outer peripheral wall 38 of the annular groove 30 due to a capillary phenomenon or the like, the intrusion water into the slit 43 adjacent to the gap 48 is a corner portion. It is possible to prevent climbing up to the respiratory chamber 42 through 90 by the uneven shape of the corner 90.

  As described above, according to the ignition coil 1, both the waterproof property and the drainage property can be improved at the same time in the breathing path 40 that connects the inside and outside of the plug hole 4. In addition, in the casing body 20 of the casing 10, the elements 30, 43, 50 (44) are all open to the axial lower end face 14a of the head 14 including the lower end faces 38a, 50a. At the time of 20 resin molding, it can be manufactured at low cost only by releasing in the axial direction.

(Other embodiments)
Although one embodiment of the present invention has been described above, the present invention is not construed as being limited to the embodiment, and can be applied to various embodiments without departing from the gist of the present invention. it can.

  Specifically, the cover 50 only needs to cover at least a portion adjacent to the respiratory chamber 42 from the outer peripheral side in the entire axial direction of the slit 43. Therefore, as shown in a modified example in FIG. 8, the lower end surface 50 a of the cover 50 is formed on the same virtual plane A as the opposing surface 61 b of the annular seal member 60 that defines the breathing chamber 42. Only a portion adjacent to the chamber 42 may be covered by the cover 50. Alternatively, as shown in FIG. 9, the cover 50 is disposed on the insertion portion side with respect to the opposing surface 61 b of the annular seal member 60 and on the opposite insertion portion side with respect to the lower end surface 38 a of the outer peripheral wall 38 of the annular groove 30. By forming the lower end surface 50a, the cover 50 may cover a portion extending across the insertion surface side and the anti-insertion region side from the opposing surface 61b in the entire axial direction of the slit 43.

  In addition, the slits 43 may be provided at circumferential positions other than the lowermost portion of the outer circumferential wall 38 of the annular groove 30 that is inclined with respect to the vertical direction. Further, the passage recesses 32 and 33 for forming the breathing passage 41 in the annular groove 30 inclined with respect to the vertical direction are provided at circumferential positions other than the uppermost portion 37a in the small-diameter recess 37 of the groove 30. Also good. Still further, the annular groove 30 and the plug hole 4 may be provided such that both axial directions are along the vertical direction.

  In addition, the seal lip 64 only needs to be in elastic contact with the outer peripheral wall 38 of the annular groove 30 on both sides of the slit 43 in the circumferential direction, and a part of the annular seal member 60 in the circumferential direction corresponding to the slit 43. For example, it may be formed in a circular arc shape. In addition, only one seal lip 64 may be provided in the axial direction of the annular seal member 60 or may not be provided on the annular seal member 60. In addition to the stick-type ignition coil 1 in which the components 101 to 106 of the transformer unit 100 are positioned straddling the inside and outside of the plug hole 4 as shown in FIG. It can be applied to an ignition coil or the like positioned on

DESCRIPTION OF SYMBOLS 1 Ignition coil, 2 Internal combustion engine, 3 Cylinder head, 4 Plug hole, 5 Spark plug, 6 Annular protrusion, 10 Casing, 12 Insertion part, 14 Head, 14a Axial lower end surface, 20 Casing body, 22 Tower part, 23 connector, 24 flange, 30 annular groove, 31 fitting recess, 32 inner passage recess, 33 outer passage recess, 34 compartment recess, 35 connection recess, 34a, 35a bottom surface (bottom surface in annular groove), 36 large diameter recess, 36a Bottom surface, 37 Small-diameter recess, 37a Top part, 38 Outer peripheral wall, 38a Lower end face (end part side end face), 38b Inner face, 38c Outer face, 38d Bottom part, 40 Breathing path, 41 Breathing path, 42 Breathing chamber, 43 Slit 44 Open space, 48 clearance, 50 cover, 50a lower end surface, 50b opening, 60 annular seal part , 61 intermediate portion, 61a outer surface, 61b top-facing surface 62 upper end 63 lower end 64 the seal lip 66 covering portion, 90 corners, 100 transformer section

Claims (8)

An ignition coil that induces an applied voltage to a spark plug in a plug hole in an internal combustion engine by a transformer section,
A casing having an insertion part inserted into the plug hole for connecting the transformer part to the spark plug, and a head arranged outside the plug hole for connecting the transformer part to an external device; ,
An annular seal member that is arranged along the circumferential direction of the plug hole and seals between the casing and the plug hole in a state in which a breathing passage communicating with the plug hole is secured;
The head comprises
An annular groove that opens toward the insertion portion and coaxially engages with the annular seal member to form a breathing chamber communicating with the breathing passage between the annular seal member;
In the outer peripheral wall of the annular groove in contact with the outer surface of the annular seal member, the respiratory chamber passes through the entire axial direction from the position adjacent to the respiratory chamber to the end surface on the insertion portion side in the radial direction. Slits to open the atmosphere outside the plug hole,
A cover that covers at least a portion adjacent to the breathing chamber from the outer peripheral side of the entire axial direction of the slit in a state where an air opening space that is open to the atmosphere outside the plug hole is secured between the slit,
An ignition coil comprising: The annular seal member has a facing surface facing the insertion portion side across the breathing chamber with respect to the bottom surface in the annular groove,
2. The ignition coil according to claim 1, wherein the slit is adjacent to the respiratory chamber in a radial direction on a side opposite to the insertion portion side with respect to the facing surface.   3. The ignition coil according to claim 2, wherein the cover covers, from the outer peripheral side, a portion straddling the insertion portion side and the opposite side of the facing surface in the slit.   The ignition coil according to any one of claims 1 to 3, wherein the cover covers the entire axial direction of the slit from the outer peripheral side.   The annular seal member has the slit in the outer circumferential wall of the annular groove with the gap opened to the atmosphere outside the plug hole between the end surface on the insertion portion side where the slit opens. The ignition coil according to any one of claims 1 to 4, further comprising a cover portion covering from the insertion portion side.   6. The annular seal member has a seal lip on an outer surface that protrudes in a radial direction and elastically contacts with an outer peripheral wall of the annular groove on both sides sandwiching the slit in the circumferential direction. Ignition coil according to.   In the head portion of the casing in which the insertion portion is inserted into the plug hole that is inclined with respect to the vertical direction, the annular groove is inclined with respect to the vertical direction, and the slit is formed on the outer peripheral wall of the annular groove. The ignition coil according to any one of claims 1 to 6, wherein the ignition coil is located at a lowermost portion. The annular seal member has a facing surface facing the insertion portion side across the breathing chamber with respect to the bottom surface in the annular groove,
The slit is adjacent to the respiratory chamber in the radial direction on the side opposite to the insertion part side than the facing surface,
8. The ignition coil according to claim 1, wherein an end surface of the annular groove on the insertion portion side is positioned below the facing surface that defines the breathing chamber. 9. .

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