JP7106901B2 - Ignition device for internal combustion engine - Google Patents

Description

The present invention relates to ignition devices for internal combustion engines.

2. Description of the Related Art Ignition devices are used as ignition means in internal combustion engines such as automobiles. The ignition device includes an ignition coil that applies a high voltage to the spark plug. Some ignition coils include a primary coil, a secondary coil, a core, and a case that accommodates them. The primary coil and secondary coil are magnetically coupled to each other. Also, the core forms a magnetic path for a magnetic field generated by energizing and interrupting the primary coil.

Here, Patent Literature 1 discloses a technique of grounding a core in order to suppress noise generated inside an ignition coil. The ignition device described in Patent Document 1 has an opening formed in the case, and the core is arranged so that a part of the core is exposed from the opening of the case. A sealing member that seals between the ignition coil and the plug hole is made of a conductive material and is in contact with both the exposed portion of the core from the opening of the case and the plug hole. As a result, the ignition coil disclosed in Patent Document 1 grounds the core to the plug hole.

WO2012/084313

However, in the ignition device described in Patent Document 1, the exposed portion of the core exposed from the opening of the case is not completely covered with the sealing member, and the exposed portion of the core is exposed to the wet environment. . Therefore, corrosion such as rust occurs in the core, and electrical connectivity between the core and the seal member may deteriorate. As a result, it is conceivable that the core may not be properly grounded.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and it is an object of the present invention to provide an ignition device for an internal combustion engine that facilitates reliable grounding of the core.

One aspect of the present invention is an ignition device (1) comprising an ignition coil (10) for igniting a spark plug (11),
The ignition coil is
a primary coil (21) and a secondary coil (22) magnetically coupled to each other;
a core (3) forming a magnetic path of the magnetic flux generated by energizing and interrupting the primary coil;
a case (4) housing the primary coil, the secondary coil, and the core;
a filling resin (23) filled in the case;
a sealing member (5) for sealing between the mounting member to which the ignition coil is mounted and the case;
a tubular conductive tube (16) electrically connected to the cylinder head;
a ground part (6) for grounding the core via the conductive tube by contacting the exposed core part (321a) of the core exposed from the case through hole (40) formed in the case. ,
The sealing member is configured to seal between the mounting member and the case in at least a radially outer region of a contact portion between the core exposed portion and the ground portion,
The ground portion is made of an elastically deformable material and has an annular main body portion attached to the seal member and a columnar portion (63) extending from the main body portion. The body portion and the columnar portion are compressed by the exposed core portion and the conductive tube in a state in which the columnar portion contacts the exposed core portion while contacting the conductive tube . in the ignition system.

In the ignition device of this aspect, the sealing member seals between the mounting member and the case at least in a radially outer region than the contact portion between the exposed core portion and the ground portion. Therefore, it is possible to prevent the contact portion between the exposed core portion and the ground portion from being exposed to water. Therefore, it is easy to prevent deterioration of the electrical connectivity between the core and the ground portion over time, and it is easy to ensure the grounding of the core.

Also, the ground portion is in contact with the core exposed portion exposed from the case through hole of the case. Therefore, the work of connecting the ground portion and the core can be easily and reliably performed. Furthermore, since the ground part is connected to the part of the core exposed from the case, even if the filling resin filled in the case thermally contracts or expands, stress is generated at the connection part between the ground part and the core. Hateful. This also facilitates maintaining the electrical connection between the grounding portion and the core.

As described above, according to this aspect, it is possible to provide an ignition device for an internal combustion engine in which the grounding of the core can be easily ensured.
It should be noted that the symbols in parentheses described in the claims and the means for solving the problems indicate the corresponding relationship with the specific means described in the embodiments described later, and limit the technical scope of the present invention. not a thing

Sectional drawing of the ignition device in Embodiment 1. FIG. FIG. 2 is an enlarged view of the periphery of the ground portion in FIG. 1; FIG. 2 is a top view of the sealing member according to the first embodiment; FIG. 2 is a top view of the ground portion in the first embodiment; FIG. 4 is a conceptual diagram showing how the upper end of the grounding portion is compressed and is in contact with the side surface of the recessed core according to the first embodiment; FIG. 2 is a cross-sectional view of the outer core and the ground portion taken along the line VI-VI. FIG. 2 is a cross-sectional view of the engine body in Embodiment 1; FIG. 4 is an enlarged cross-sectional view of the periphery of the ground portion, showing a modified form of the first embodiment; FIG. 4 is an enlarged cross-sectional view around the grounding portion, showing another modification of the first embodiment; Sectional drawing of the ignition device in Embodiment 2. FIG. FIG. 11 is an enlarged view of the periphery of the ground portion in FIG. 10; FIG. 10 is a top view of a sealing member according to the second embodiment; FIG. 10 is a top view of a ground portion in Embodiment 2; Sectional drawing of the ignition device in Embodiment 3. FIG. FIG. 14 is an enlarged view of the periphery of the ground portion in FIG. 14; The top view of the head cover in Embodiment 3. FIG. A cross-sectional view taken along line XVII-XVII in FIG. A cross-sectional view taken along line XVIII-XVIII in FIG. FIG. 18 is a cross-sectional view showing an example of the positional relationship between the grounding portion and the core recessed portion before the ignition coil is bolted, and corresponding to FIG. 17 ; FIG. 19 is a cross-sectional view showing an example of the positional relationship between the grounding portion and the core recessed portion before bolting the ignition coil to the ignition coil, and corresponding to FIG. 18 ;

(Embodiment 1)
An embodiment of an ignition device for an internal combustion engine will be described with reference to FIGS. 1 to 7. FIG.
As shown in FIG. 1, an ignition device 1 for an internal combustion engine of this embodiment includes an ignition coil 10 that ignites the spark plug 11 by applying a high voltage to the spark plug 11 (see FIG. 7).

The ignition coil 10 has a primary coil 21 , a secondary coil 22 , a core 3 , a case 4 , a filling resin 23 and a sealing member 5 . Primary coil 21 and secondary coil 22 are magnetically coupled to each other. The core 3 constitutes a magnetic path for magnetic flux generated by energizing and interrupting the primary coil 21 . In this embodiment, the core 3 has a central core 31 and a peripheral core 32, which will be described later.

Case 4 accommodates primary coil 21 , secondary coil 22 and core 3 . The filling resin 23 is filled in the case 4 . The sealing member 5 seals between the mounting member to which the ignition coil 10 is mounted and the case 4 . Here, the mounting member is the head cover 15 .

The ignition device 1 has a ground portion 6 . As shown in FIG. 2, the ground portion 6 contacts the exposed core portion 321a of the core 3 exposed from the case through hole 40 formed in the case 4 to ground the core 3. As shown in FIG. The seal member 5 seals between the head cover 15 and the case 4 in at least a region radially outside the contact portion between the core exposed portion 321 a and the ground portion 6 .

In this specification, the mounting direction of the ignition coil 10 with respect to the mounting member (head cover 15) is referred to as a vertical direction Z. As shown in FIG. It should be noted that the up-down expression of the up-down direction Z is for convenience, and the up-down direction Z does not need to be parallel to the vertical direction. Further, in this specification, the term “radial direction” simply means the radial direction of the seal member 5 . The radial direction is orthogonal to the up-down direction Z.
Hereinafter, this embodiment will be described in detail.

The ignition device 1 of this embodiment is used as means for igniting an air-fuel mixture in an internal combustion engine such as a vehicle engine. The ignition device 1 of this embodiment has an ignition coil 10 attached to an engine body 13 . As shown in FIG. 7, the engine body 13 has a cylinder head 14, a head cover 15, a conductive tube 16, and a cover seal 17. As shown in FIG.

The cylinder head 14 has a plug hole 141 into which the ignition coil 10 is inserted and the spark plug 11 is attached. The head cover 15 covers the cylinder head 14 from one side in the vertical direction Z. As shown in FIG. The head cover 15 has an insertion hole 151 opening toward the plug hole 141 of the cylinder head 14 . The head cover 15 protrudes toward the opposite side of the cylinder head 14 in the vertical direction Z, and has a boss 152 for fastening the ignition coil 10 with a bolt. In this embodiment, the head cover 15 may be made of resin or metal. Hereinafter, the side of the cylinder head 14 on which the head cover 15 is arranged in the vertical direction Z will be referred to as the upper side, and the opposite side will be referred to as the lower side.

The conductive tube 16 is made of a conductive material, such as metal, and formed into a cylindrical shape, and is arranged to connect the plug hole 141 and the insertion hole 151 of the head cover 15 .

The cover seal 17 has a substantially annular shape. The cover seal 17 includes a cover-side tight contact portion 171 that fits around the entire periphery of the insertion hole 151 of the head cover 15 and a tube-side tight contact portion 172 that elastically adheres to the entire circumference of the outer peripheral surface of the conductive tube 16 in the radial direction. have. Thereby, the cover seal 17 seals between the conductive tube 16 and the head cover 15 .

A positioning protrusion 173 projecting upward is formed on the upper surface of the cover-side contact portion 171 along the entire circumference of the cover-side contact portion 171 . As will be described later, the positioning projection 173 has a role of positioning the sealing member 5 of the ignition coil 10 .

Also, the lower end of the conductive tube 16 is fitted into a stepped portion 142 formed above the plug hole 141 . As a result, the conductive tube 16 and the cylinder head 14 are sealed, and the conductive tube 16 is electrically connected to the cylinder head 14 .

The ignition coil 10 is inserted and arranged inside the plug hole 141 , the insertion hole 151 and the conductive tube 16 . As shown in FIG. 1, in this embodiment, the ignition coil 10 includes a ground portion 6 in addition to the primary coil 21, secondary coil 22, core 3, case 4, filling resin 23, and sealing member 5 described above.

The primary coil 21 and the secondary coil 22 are concentrically wound and arranged overlapping the inner and outer circumferences. The direction in which the winding axes of the primary coil 21 and the secondary coil 22 extend is perpendicular to the vertical direction Z, and this direction is hereinafter referred to as the "lateral direction X". A direction orthogonal to both the vertical direction Z and the horizontal direction X will be referred to as a vertical direction Y hereinafter.

A central core 31 is arranged inside the primary coil 21 and the secondary coil 22 . The central core 31 has a columnar shape elongated in the lateral direction X. As shown in FIG.

An outer core 32 is arranged so as to surround the outer circumferences of the primary coil 21 and the secondary coil 22 in the horizontal direction X and the vertical direction Y. As shown in FIG. Here, the outer core 32 is a substantially rectangular frame that opens in the vertical direction Z. As shown in FIG. The outer peripheral core 32 is formed parallel to the horizontal direction X and the vertical direction Z with a pair of vertical core portions 321 that are formed parallel to the vertical direction Y and the vertical direction Z and are formed to face each other in the horizontal direction X. and a pair of horizontal core portions (not shown) formed so as to face each other in the longitudinal direction Y. The central core 31 is arranged inside the pair of vertical core portions 321 . One end of the central core 31 in the horizontal direction X is in contact with one vertical core portion 321 , thereby electrically connecting the central core 31 and the outer peripheral core 32 .

As shown in FIG. 1, of the pair of vertical core portions 321 of the outer peripheral core 32, the lower surface of the vertical core portion 321 positioned on one side in the horizontal direction X is formed with a core recess 321b recessed upward. As shown in FIG. 6, the core concave portion 321b is formed in the center of the vertical core portion 321 in the horizontal direction X. As shown in FIG. The core recess 321b has a rectangular shape with rounded corners elongated in the vertical direction Y. As shown in FIG. Although the details will be described later, the ground portion 6 is inserted into the core concave portion 321b. As shown in FIG. 1, of the lower surface of the vertical core portion 321, at least the portion where the core concave portion 321b is formed abuts on the bottom wall portion 412 of the case 4, which will be described later. In this embodiment, the entire lower surface of the outer core 32 is in contact with the bottom wall portion 412 of the case 4 .

As shown in FIG. 1, the central core 31 and the outer core 32 are made of a soft magnetic material. The central core 31 and the outer core 32 are formed by laminating a plurality of electromagnetic steel sheets. The central core 31 and the outer core 32 constitute a closed magnetic circuit through which the magnetic flux passes. A magnetic flux generated when the primary coil 21 is energized and interrupted passes through the closed magnetic circuit.

As shown in FIG. 1 , the case 4 includes a housing portion 41 and a high pressure tower portion 42 . Case 4 has electrical insulation. The housing portion 41 houses the primary coil 21 , the secondary coil 22 , the central core 31 , the outer core 32 , and the filling resin 23 . The high-pressure tower portion 42 is formed downward from the accommodation portion 41 .

As shown in FIG. 1 , the housing portion 41 has a side wall portion 411 and a bottom wall portion 412 . The side wall portion 411 surrounds the primary coil 21 , the secondary coil 22 , the central core 31 , and the outer peripheral core 32 from four directions perpendicular to the vertical direction Z. As shown in FIG. The side wall portion 411 has an open upper end and a lower end closed by a bottom wall portion 412 .

A connector portion 413 is fitted to a portion of the side wall portion 411 on one side in the lateral direction X. As shown in FIG. Although not shown, the connector portion 413 is connected to a connector at the end of a wire harness connected to an external device such as an engine control unit. Note that the connector portion 413 may be formed integrally with the side wall portion 411 .

A flange portion 414 is formed to project from the side wall portion 411 on the opposite side of the connector portion 413 in the horizontal direction X. As shown in FIG. A bolt insertion hole 414a is formed through the flange portion 414 in the vertical direction Z. As shown in FIG. A bolt B for screwing the ignition coil 10 to the boss 152 of the head cover 15 is inserted into the bolt insertion hole 414a.

The bottom wall portion 412 is formed in a planar direction perpendicular to the vertical direction Z so as to close the lower end portion of the side wall portion 411 . An upper surface of the bottom wall portion 412 is formed with an arrangement groove portion 412a into which the lower end portion of the outer peripheral core 32 is inserted. The arrangement groove portion 412a is formed in the entire area obtained by projecting the entire lower surface of the outer peripheral core 32 onto the bottom wall portion 412 in the vertical direction Z, and has a rectangular annular shape. The entire lower surface of the outer peripheral core 32 is in contact with the bottom surface of the arrangement groove portion 412a.

As shown in FIG. 2, a case through hole 40 penetrating in the vertical direction Z is formed directly below the core concave portion 321b of the outer peripheral core 32 in the arrangement groove portion 412a. As shown in FIG. 6, the case through hole 40 is formed to be larger than the core concave portion 321b in all directions perpendicular to the vertical direction Z. As shown in FIG. That is, the case through hole 40 is formed to be one size larger than the core concave portion 321b. In addition, in FIG. 6, the position of the case through hole 40 when viewed from the up-down direction Z is indicated by a dashed line.

The case through-hole 40 is elongated in the circumferential direction (hereinafter sometimes simply referred to as the circumferential direction) around the central axis of the ignition coil 10 . In this embodiment, the case through-hole 40 is elongated in the vertical direction Y and has a rectangular shape with rounded corners.

When viewed in the vertical direction Z, the core concave portion 321b is accommodated inside the case through hole 40 . As shown in FIG. 2, the core recess 321b constitutes a core exposed portion 321a exposed from the case through hole 40. As shown in FIG. The case through-hole 40 is closed by a portion of the lower surface of the outer core 32 around the core recess 321b. As a result, when the case 4 is filled with the filling resin 23 , the filling resin 23 does not leak out of the case 4 through the case through hole 40 .

As shown in FIG. 1, the central portion of the bottom wall portion 412 is open, and the high-pressure tower portion 42 is formed to protrude downward from the periphery of this opening. The high-pressure tower portion 42 has a substantially cylindrical shape, and its inner space communicates with the opening of the bottom wall portion 412 .

A high-voltage output terminal 101 is press-fitted into the upper end portion of the high-voltage tower portion 42 so as to block the opening of the upper end of the high-voltage tower portion 42 . As a result, the upper side of the inner space of the high-pressure tower section 42 is closed. The high voltage output terminal 101 serves to prevent the filled resin 23 from leaking out of the case 4 . The high voltage output terminal 101 is connected to the secondary coil 22 via the connection member 102 on the upper side.

Components of the ignition coil 10 such as the primary coil 21, the secondary coil 22, the central core 31, and the outer core 32 are housed in the housing portion 41, and the upper end portion of the high voltage tower portion 42 is closed by the high voltage output terminal 101. In this state, the filling resin 23 is filled from the opening in the upper part of the case 4 . As a result, each component housed in the housing portion 41 is resin-sealed with the filling resin 23 . The filling resin 23 is made of thermosetting resin such as epoxy resin, and has a smaller coefficient of linear expansion than the case 4 .

The seal member 5 is fitted to the high-pressure tower portion 42 from below the high-pressure tower portion 42 . The seal member 5 seals between the case 4 and the head cover 15 . The seal member 5 has a substantially cylindrical shape and is made of a material that is elastically deformable and has electrical insulation. The sealing member 5 is made of silicone rubber, for example.

The seal member 5 includes a first seal portion 51 located at the upper end portion and formed in an annular shape extending in the radial direction, and a cylindrical second seal portion 51 extending downward from the inner peripheral end of the first seal portion 51 . and two seal portions 52 .

The upper surface of the first seal portion 51 is in close contact with the lower surface of the bottom wall portion 412 of the case 4 . As shown in FIG. 2 , a seal through-hole 50 that straightly penetrates the first seal portion 51 in the up-down direction Z is formed below the core concave portion 321 b and the case through-hole 40 in the first seal portion 51 .

As shown in FIG. 6, the seal through-hole 50 is formed to be larger than the core recess 321b in all directions perpendicular to the up-down direction Z. As shown in FIG. That is, the seal through-hole 50 is formed one size larger than the core concave portion 321b. When viewed in the vertical direction Z, the seal through-hole 50 has the same shape as the case through-hole 40 . That is, as shown in FIGS. 3 and 6, the seal through hole 50 is elongated in the circumferential direction. Further, in the present embodiment, the seal through-hole 50 is elongated in the vertical direction Y and has a rectangular shape with rounded corners. 6 indicates not only the position of the case through-hole 40 but also the position of the seal through-hole 50 when viewed in the vertical direction Z. As shown in FIG.

In the present embodiment, the inner space of the core concave portion 321b, the inner space of the case through hole 40, and the inner space of the seal through hole 50 are formed so as to be aligned straight in the vertical direction Z when viewed in the vertical direction Z.

As shown in FIGS. 1 and 2, the first seal portion 51 has an annular seal engaging portion 511 protruding downward on the entire circumference of the outer peripheral end thereof. As shown in FIG. 2 , the seal engaging portion 511 is formed at a position on the outer peripheral side of the seal through hole 50 . As shown in FIG. 1, the seal engaging portion 511 is engaged with the positioning convex portion 173 so as to cover the positioning convex portion 173 of the cover seal 17 from the outer peripheral side. Thereby, the seal member 5 is positioned with respect to the cover seal 17 .

As shown in FIGS. 1 and 2, the lower end of the seal engaging portion 511 is in close contact with the boundary between the cover seal 17 and the head cover 15 . At least the upper surface of the region where the seal engaging portion 511 of the first seal portion 51 is formed is in close contact with the lower surface of the bottom wall portion 412 . Thereby, the seal member 5 seals between the head cover 15 and the case 4 in at least a radially outer region of the contact portion between the core exposed portion 321 a and the ground portion 6 .

As shown in FIG. 3, the first seal portion 51 is formed with a ventilation passage 512 for communicating the inside and outside of the plug hole 141 and for ventilating the inside and outside of the plug hole 141 . The ventilation passage 512 communicates with a ventilation groove 512a formed on the entire circumference near the outer peripheral end of the upper surface of the first seal portion 51 and a part of the ventilation groove 512a, and penetrates the first seal portion 51 in the vertical direction Z. and ventilation holes 512b. The ventilation groove 512a has an outside air communication portion 512c that communicates with the outer space of the ignition coil 10. As shown in FIG. The ventilation groove 512 a also has four pool grooves 512 d to prevent moisture from passing through the ventilation passage 512 . The pool groove 512d is formed as a groove that is larger and deeper than the portions other than the pool groove 512d in the ventilation groove 512a, and has a function of storing intruding moisture. 512 d of four pool groove|channels are formed in the circumferential direction at equal intervals. Also, the ventilation hole 512b is formed at a position 180° opposite to the outside air passage in the circumferential direction.

As shown in FIG. 1 , the second seal portion 52 has a substantially cylindrical shape and is in close contact with the outer peripheral surface of the high-pressure tower portion 42 . An insulating pipe 103 is fitted to the second seal portion 52 from below. The insulating pipe 103 will be described later. A ground portion 6 is attached to the seal member 5 below the first seal portion 51 and on the outer peripheral side of the second seal portion 52 .

The ground portion 6 has a substantially annular shape. The ground portion 6 is made of a material that is electrically conductive and elastically deformable. For example, the ground portion 6 can be made of conductive silicone rubber or conductive EPDM (that is, conductive ethylene propylene diene rubber).

In this embodiment, the grounding portion 6 is configured by one member. The ground portion 6 is attached to the seal member 5 so as to be in close contact with the lower surface of the first seal portion 51 and the outer peripheral surface of the second seal portion 52 . As shown in FIG. 2, the grounding portion 6 includes an annular portion 61 that is in close contact with the lower surface of the first seal portion 51 of the seal member 5, and a second seal portion extending downward from the inner peripheral end of the annular portion 61. 52 and a columnar portion 63 extending from the annular portion 61 .

As shown in FIG. 4 , the annular portion 61 has an annular shape, and its upper surface is in close contact with the entire lower surface of the portion of the first seal portion 51 excluding the seal engaging portion 511 . Further, the outer peripheral end of the annular portion 61 abuts on the upper end of the positioning protrusion 173 of the cover seal 17 . That is, the outer peripheral end of the annular portion 61 is sandwiched in the up-down direction Z by the first seal portion 51 and the positioning convex portion 173 . The outer diameter of the annular portion 61 is the same as the inner diameter of the seal engaging portion 511 of the seal member 5 .

A slit 64 is formed in the annular portion 61 so as not to block the ventilation hole 512b of the sealing member 5 described above. The slit 64 is formed directly below the ventilation hole 512b of the seal member 5. As shown in FIG. As a result, the ventilation hole 512b of the seal member 5 is not blocked by the annular portion 61, and the inside and outside of the plug hole 141 are communicated.

As shown in FIG. 2 , the tubular portion 62 has a cylindrical shape and is in close contact with the entire outer peripheral surface of the upper end portion of the second seal portion 52 . Further, the tubular portion 62 is compressed in the vertical direction Z from the free state, and the lower end portion of the tubular portion 62 elastically contacts the conductive tube 16 over the entire circumference. Thereby, the ground portion 6 is grounded via the conductive tube 16 .

The columnar portion 63 is formed in a columnar shape so as to protrude upward from the upper surface of the annular portion 61 . The columnar portion 63 penetrates through the insides of the seal through hole 50 and the case through hole 40 and is in contact with the core exposed portion 321a. As a result, the ground portion 6 is electrically connected to the outer core 32 without contacting the filling resin 23 inside the case 4 . The columnar portion 63 is inserted and fitted into the core concave portion 321b.

As shown in FIG. 6, the columnar portion 63 is formed smaller than each of the seal through hole 50 and the case through hole 40 in all directions perpendicular to the vertical direction Z. As shown in FIG. That is, it is formed one size smaller than the seal through-hole 50 and the case through-hole 40 .

As shown in FIG. 6, the columnar portion 63 is smaller in the vertical direction Y than the core recess 321b, but is formed in the horizontal direction X to have the same size as the core recess 321b.

Here, the columnar portion 63 is arranged in a state compressed in the vertical direction Z from the free state. Therefore, as shown in FIG. 5, when the ground portion 6 is attached to the ignition device 1, the upper end portion of the columnar portion 63 is elastically adhered to the bottom surface of the core recess portion 321b. Furthermore, the upper end of the columnar portion 63 is expanded in the direction orthogonal to the vertical direction Z by being compressed more in the vertical direction Z than in the free state. is doing. That is, the columnar portion 63 is in close contact with the core concave portion 321b at the upper end portion and both sides in the horizontal direction X. As shown in FIG. In addition, in FIG. 5, the upper end portion of the columnar portion 63 after elastic deformation is indicated by a dashed line.

As shown in FIG. 2, the ground portion 6 is in contact with the conductive tube 16 at the tubular portion 62 and is in contact with the core recess 321b (that is, the core exposed portion 321a) at the columnar portion 63. As shown in FIG. As a result, the outer core 32 is grounded to the cylinder head 14 via the ground portion 6 and the conductive tube 16 .

As shown in FIG. 1, a resistor 104 is arranged below the high voltage output terminal 101 inside the high voltage tower portion 42 . The resistor 104 is electrically connected to the high-voltage output terminal 101 on its upper side and connected to a coil spring 105, which will be described later, on its lower side. Resistor 104 has a role of suppressing noise current from spark plug 11 connected to ignition coil 10 from being transmitted to secondary coil 22 .

The coil spring 105 is a conductive spring configured to be elastically deformable in the vertical direction Z. As shown in FIG. The coil spring 105 elastically contacts the resistor 104 at its upper end and elastically contacts the terminal of the spark plug 11 at its lower end. Thereby, the coil spring 105 electrically connects the resistor 104 and the ignition plug 11 . Along with this, the secondary coil 22 and the spark plug 11 are electrically connected via the connection member 102 , the high voltage output terminal 101 , the resistor 104 and the coil spring 105 .

The coil spring 105 is arranged inside an insulating pipe 103 having electrical insulation. The insulating pipe 103 is formed by forming an insulating resin into a substantially cylindrical shape. Although not shown, the coil spring 105 is engaged with the insulating pipe 103 in the vertical direction Z, so that the insulating pipe 103 holds the coil spring 105 . The insulating pipe 103 is fitted to the second seal portion 52 of the seal member 5 at its upper end. Although not shown, a plug cap made of cylindrical rubber is fitted to the lower end of the insulating pipe 103 . A spark plug 11 is fitted into the plug cap.

Next, the effects of this embodiment will be described.
In the ignition device 1 of the present embodiment, the seal member 5 seals between the mounting member and the case 4 in at least a region radially outside the contact portion between the core exposed portion 321 a and the ground portion 6 . Therefore, it is possible to prevent the contact portion between the core exposed portion 321a and the ground portion 6 from being exposed to water. Therefore, it is easy to prevent deterioration of the electrical connectivity between the core 3 and the grounding portion 6 over time, and it is easy to ensure the grounding of the core 3 .

Also, the grounding portion 6 is in contact with the core exposed portion 321 a exposed from the case through hole 40 of the case 4 . Therefore, the connection work between the ground portion 6 and the core 3 can be easily and reliably performed. Furthermore, since the ground portion 6 is connected to the portion of the core 3 exposed from the case 4, the ground portion 6 and the core 3 are connected to each other even if the filling resin 23 filled in the case 4 is thermally contracted or thermally expanded. Stress is less likely to occur in the connection part of This also facilitates maintaining the electrical connection between the grounding portion 6 and the core 3 .

Also, a portion of the ground portion 6 is in contact with the conductive tube 16 . Therefore, the outer core 32 can be grounded to the cylinder head 14 via the conductive tube 16 . Therefore, the outer core 32 can be grounded regardless of whether the head cover 15 is conductive. Therefore, the head cover 15 can be made of a conductive metal, for example, or it can be made of a non-conductive resin, for example, and the material can be freely selected. .

Also, the grounding portion 6 is made of an elastically deformable material, and is elastically adhered to the exposed core portion 321a. Therefore, it is easy to maintain close contact between the ground portion 6 and the exposed core portion 321a. As a result, the outer core 32 can be stably grounded.

At least one of the ground portion 6 and the core exposed portion 321a passes through the seal through hole 50 formed in the seal member 5 and contacts the other. Therefore, the ground portion 6 and the exposed core portion 321a can be connected with a simple structure.

Further, each of the seal through-hole 50 and the case through-hole 40 is elongated in the circumferential direction. Therefore, even if the positions of the seal through-hole 50 and the case through-hole 40 in the circumferential direction are not strictly aligned with the position of the grounding part 6, the grounding part 6 can be inserted into the seal through-hole 50 and the case through-hole 40. Therefore, the productivity of the ignition coil 10 can be easily improved.

One of the exposed core portion 321a and the ground portion 6 has a concave portion (the core concave portion 321b in this embodiment), and the other has a convex portion (a columnar portion 63 in this embodiment) that is inserted and fitted into the concave portion. have Therefore, the connection between the exposed core portion 321a and the ground portion 6 can be easily maintained.

In this embodiment, the core exposed portion 321a has a concave portion and the grounding portion 6 has a convex portion. Conversely, as shown in FIG. However, a structure in which the ground portion 6 has a concave portion can also be adopted. In this case also, similar effects can be obtained. Furthermore, as shown in FIG. 9, the core exposed portion 321a may be formed on a flat surface, and the ground portion 6 may be in surface contact with the core exposed portion 321a.

As described above, according to the present embodiment, it is possible to provide an ignition device for an internal combustion engine that facilitates grounding of the core.

(Embodiment 2)
As shown in FIGS. 10 to 13, this embodiment is an embodiment in which the shape of the seal through-hole 50 of the seal member 5 and the shape of the ground portion 6 are changed with respect to the first embodiment.

As shown in FIGS. 10 to 12, the seal through hole 50 has a first hole portion 501 and a second hole portion 502. As shown in FIGS. The first hole portion 501 is a recess formed in the upper surface of the seal member 5 . The first hole portion 501 is formed in the radial direction from the area below the core exposed portion 321a on the upper surface of the first seal portion 51 to the position of the outer peripheral end of the second seal portion 52 in the radial direction. When viewed from the up-down direction Z, the radial outer end portion of the first hole portion 501 is formed into a curved surface that bulges toward the outer peripheral side.

As shown in FIGS. 10 to 12, the second hole portion 502 is a hole extending straight through the first seal portion 51 in the up-down direction Z. As shown in FIGS. The second hole portion 502 is formed downward from the inner peripheral end of the first hole portion 501 . The inner peripheral end of the second hole portion 502 is formed continuously with the outer peripheral surface of the second seal portion 52 .

The grounding portion 6 includes a first grounding portion 65 arranged to fill the first hole portion 501 of the seal through hole 50, and a second hole portion extending downward from the inner peripheral end of the first grounding portion 65. It has a second grounding portion 66 arranged to fill the space 502 and a third grounding portion 67 extending upward from the vicinity of the outer peripheral end of the first grounding portion 65 .

As shown in FIG. 11 , the first grounding portion 65 is formed in a plate shape along the lower surface of the bottom wall portion 412 of the case 4 . The first grounding portion 65 has the same shape as the first hole portion 501 and fits in the first hole portion 501 perfectly.

The second ground portion 66 is formed in a plate shape along the outer peripheral surface of the second seal portion 52 of the seal member 5 . The second grounding portion 66 is compressed in the vertical direction Z from its free state, and the lower end of the second grounding portion 66 is in elastic contact with the conductive tube 16 . Thereby, the ground portion 6 is grounded via the conductive tube 16 . The second grounding portion 66 has the same cross-sectional shape as the second hole portion 502 and penetrates through the second hole portion 502 .

The third ground portion 67 is formed upward from the outer peripheral edge of the first ground portion 65 . As shown in FIG. 13, the third ground portion 67 is formed from the central portion of the first ground portion 65 in the circumferential direction. As shown in FIG. 11, the third grounding portion 67 passes through the case through hole 40 and is inserted into the core concave portion 321b of the outer peripheral core 32. As shown in FIG. The size relationship and positional relationship of the third ground portion 67 with respect to the core concave portion 321b and the case through hole 40 are the same as those of the columnar portion 63 of the first embodiment.

Others are the same as those of the first embodiment.
Note that, of the reference numerals used in the second and subsequent embodiments, the same reference numerals as those used in the previous embodiments represent the same components as those in the previous embodiments, unless otherwise specified.

In this embodiment, since the formation range of the ground portion 6 is a part of the circumferential direction, the size of the ground portion 6 can be reduced. Therefore, it is possible to reduce the material cost of the ground portion 6, which leads to cost reduction.
In addition, it has the same effects as those of the first embodiment.

(Embodiment 3)
In this embodiment, as shown in FIGS. 14 to 19, the mounting member to which the ignition coil 10 is mounted has conductivity, and a part of the mounting member constitutes the ground portion 6. As shown in FIG. Also in this embodiment, the mounting member is the head cover 15 . In this embodiment, the head cover 15 is made of metal.

As shown in FIG. 14, the engine body 13 has a head cover 15 and a cylinder head (not shown). 17) is not included. The head cover 15 has an insertion hole 151 opening toward the plug hole of the cylinder head and a boss 152 as in the first embodiment. Although not shown, the head cover 15 is directly attached to the cylinder head, thereby grounding the head cover 15 to the cylinder head.

As shown in FIGS. 14 to 16, the head cover 15 has an engaging protrusion 153 around the insertion hole 151 on the upper surface thereof for engaging the sealing member 5 of the ignition coil 10. As shown in FIGS. As shown in FIG. 16 , the engagement protrusion 153 is formed in an annular shape so as to surround the insertion hole 151 . The outer peripheral end of the engaging projection 153 is formed in a substantially perfect circle centered on the central axis of the insertion hole 151 . 14 and 15, the seal engaging portion 511 of the seal member 5 is engaged with the outer peripheral side of the engaging convex portion 153. As shown in FIGS.

As shown in FIG. 16, the engaging protrusion 153 has an inner circumferential protrusion 154 that protrudes inward from a portion of the engaging protrusion 153 in the circumferential direction. As shown in FIGS. 14 and 15, the inner peripheral protruding portion 154 is formed so as to partially overlap the exposed core portion 321a in the vertical direction Z. As shown in FIG.

As shown in FIGS. 14 to 16, the ground portion 6 is formed upward from the inner circumferential projecting portion 154 . The ground portion 6 is formed in a cylindrical shape extending straight in the vertical direction Z. As shown in FIG. As shown in FIGS. 15 and 18, the ground portion 6 passes through the insides of the seal through hole 50 and the case through hole 40, is inserted into the core recess 321b, and extends in the vertical direction Z on the bottom surface of the core recess 321b. abutting. As a result, the outer core 32 is grounded to the cylinder head through the head cover 15 including the ground portion 6 .

As shown in FIG. 17, also in the present embodiment, the core recess 321b has a rectangular shape with rounded corners elongated in the vertical direction Y. As shown in FIG. The ground portion 6 is formed to be smaller than the core recess 321b in the vertical direction Y and slightly smaller in the horizontal direction X than the core recess 321b. As shown in FIGS. 17 and 18, in this embodiment, the outer peripheral surface of the grounding portion 6 is in contact with one side surface in the vertical direction Y of the core concave portion 321b. 19 and 20, the earth portion 6 and the core recess portion 321b are not in contact with each other in the vertical direction Y before the ignition coil 10 is bolted to the boss 152 of the head cover 15. Assume. Even in this case, the ignition coil 10 rotates with the bolt B with respect to the head cover 15 when the ignition coil 10 is bolted to the boss 152 as shown in FIG. Therefore, when the ignition coil 10 is bolted to the boss 152, the ground portion 6 and the core concave portion 321b are in contact with each other in the vertical direction Y. As shown in FIG. Alternatively, the diameter of the ground portion 6 may be made slightly longer than the length of the core recess 321b in the horizontal direction X so that the ground portion 6 is pressed against the core recess 321b.
Others are the same as those of the first embodiment.

In this embodiment, a mounting member to which the ignition coil 10 is mounted, that is, a portion of the head cover 15 constitutes the grounding portion 6 . Therefore, there is no need to use a separate member for grounding the core 3, and an increase in the number of parts can be prevented.

Furthermore, in the configuration of this embodiment, one of the core exposed portion 321a and the ground portion 6 has a recess, and the other is inserted and fitted into the recess. As a result, when the ignition coil 10 is bolted to the boss 152 of the head cover 15, if the ignition coil 10 also rotates with the rotation of the bolt B, the rotation of the ignition coil 10 is stopped by the abutment of the concave portion and the convex portion. . As a result, contact between the concave portion and the convex portion can be easily ensured, and excessive rotation of the ignition coil 10 accompanying the rotation of the bolt B can be prevented. By preventing excessive rotation of the ignition coil 10, it is easy to maintain close contact between the seal member 5 and the cylinder head .
In addition, it has the same effects as those of the first embodiment.

The present invention is not limited to the embodiments described above, and can be applied to various embodiments without departing from the scope of the invention.

REFERENCE SIGNS LIST 1 ignition device 10 ignition coil 11 spark plug 23 filling resin 3 core 321a core exposed portion 4 case 40 case through hole 5 sealing member 6 ground portion

Claims (5)

An ignition device (1) comprising an ignition coil (10) for igniting a spark plug (11),
The ignition coil is
a primary coil (21) and a secondary coil (22) magnetically coupled to each other;
a core (3) forming a magnetic path of the magnetic flux generated by energizing and interrupting the primary coil;
a case (4) housing the primary coil, the secondary coil, and the core;
a filling resin (23) filled in the case;
a sealing member (5) for sealing between the mounting member to which the ignition coil is mounted and the case;
a tubular conductive tube (16) electrically connected to the cylinder head;
Previouscontacting the core exposed portion (321a) of the core exposed from the case through hole (40) formed in the caseVia said conductive tubeA ground part (6) for grounding the coreWhen,with
The sealing member seals between the mounting member and the case in at least a radially outer region of a contact portion between the core exposed portion and the ground portion.is configured as
The ground portion is made of an elastically deformable material and has an annular main body portion attached to the seal member and a columnar portion (63) extending from the main body portion. The main body and the columnar portion are compressed by the exposed core portion and the conductive tube in a state in which the columnar portion contacts the exposed core portion while contacting the conductive tube., ignition devices for internal combustion engines. The ignition device further includes a cylinder head (14) having a plug hole (141), and a head cover (15) having an insertion hole (151) opening toward the plug hole and constituting the mounting member. death,
The conductive tube is arranged to connect the plug hole and the insertion hole,
2. The ignition device for an internal combustion engine according to claim 1, wherein said ignition coil is inserted inside said plug hole, said insertion hole, and said conductive tube. 3. The ignition for an internal combustion engine according to claim 1, wherein at least one of said ground portion and said core exposed portion penetrates through a seal through-hole (50) formed in said seal member and is in contact with the other. Device. 4. The ignition device for an internal combustion engine according to claim 3 , wherein each of said seal through-hole and said case through-hole is elongated in a circumferential direction around a central axis of said ignition coil. The ignition device for an internal combustion engine according to any one of claims 1 to 4 , wherein one of said core exposed portion and said ground portion has a recess (321b) and the other is inserted into said recess.

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