阅读说明：本技术 用于内燃发动机中的点火线圈单元以及点火系统 (Ignition coil unit for use in internal combustion engine and ignition system ) 是由 秋本克德 于 2019-06-26 设计创作，主要内容包括：一种点火线圈单元附接至发动机本体。发动机本体包括具有塞孔的气缸盖以及通过具有面向塞孔的开口孔而覆盖气缸盖的盖罩。点火线圈单元包括产生高压的线圈单元以及将线圈单元与火花塞联接的筒形联接单元。联接单元包括：柔性密封部段,其装配到高压塔的外周表面；以及更硬的接头,其装配到密封部段的前端。密封部段包括用于紧密接触盖罩的附着部以及在Z轴线方向上至少位于附着部和接头之间的颈部。颈部通过径向向内部分地收缩密封部段的外周表面而形成。(An ignition coil unit is attached to an engine block. The engine body includes a cylinder head having a plug hole and a head cover covering the cylinder head by having an open hole facing the plug hole. The ignition coil unit includes a coil unit generating a high voltage and a cylindrical coupling unit coupling the coil unit with a spark plug. The coupling unit includes: a flexible seal section fitted to an outer peripheral surface of the high-pressure column; and a harder joint fitted to the front end of the sealing section. The sealing section includes an attachment portion for closely contacting the cap and a neck portion located at least between the attachment portion and the joint in the Z-axis direction. The neck portion is formed by partially contracting an outer peripheral surface of the sealing section radially inward.)

1. An ignition coil unit for use in an internal combustion engine as an accessory of an engine block, the engine block including a cylinder head having a plug hole and a cover covering the cylinder head by having an opening hole facing the plug hole, the ignition coil unit comprising:

a coil unit for generating a high voltage, the coil unit comprising:

a main housing for accommodating components used in the coil unit, and

an auxiliary housing for accommodating a cylindrical high-pressure column that protrudes from the main housing to a front end side in an axial direction; and

a cylinder coupling unit for coupling the coil unit to a spark plug,

the cartridge coupling unit includes:

a flexible seal section fitted to an outer peripheral surface of the high-pressure column while extending in an axial direction of the cylindrical coupling unit,

the flexible sealing section comprises:

a first fitting section located at a front end of the flexible sealing section, and an attachment portion closely contacting the cover, an

A joint aligned with the flexible sealing section in the axial direction,

the joint having a second fitting section that fits to the first fitting section of the flexible sealing section, the joint being harder than the sealing section,

wherein the flexible sealing section further comprises a neck portion located at least in a region between the attachment portion and the joint in the axial direction,

wherein the neck is formed by narrowing the sealing section radially inward.

2. The ignition coil unit according to claim 1, wherein the high-voltage tower includes a holding portion that is located on a base end side with respect to the joint in the axial direction to prevent removal of the seal section, the holding portion protruding radially outward,

wherein the sealing section comprises a recess for accommodating the retaining portion, wherein the neck is located at a position overlapping the recess in a radial direction.

3. The ignition coil unit according to claim 1, wherein the sealing section includes a boss located adjacent to a front end of the neck portion in the axial direction, the boss extending radially outward from an outer peripheral surface of the sealing section.

4. The ignition coil unit according to claim 1, wherein the neck portion has a prescribed length in the axial direction.

5. The ignition coil unit of claim 1 wherein said sealing section has a minimum diameter at said neck.

6. The ignition coil unit according to claim 1, wherein the joint fitting section is cylindrical and includes:

an inner peripheral step that is inclined radially outward as the inner peripheral surface approaches the base end of the seal section in the axial direction, and

a base end inner peripheral surface extending from one end of the inner peripheral step to a base end,

wherein a cavity is formed in the radial direction at least between the inner peripheral step or the base end inner peripheral surface and the sealing section.

7. An ignition system comprising:

a cylinder head having a plug hole;

a head cover for covering the cylinder head, the head cover having an open hole facing the plug hole; and

an ignition coil unit inserted into both the plug hole and the open hole, the ignition coil unit including:

a coil unit for generating a high voltage, the coil unit comprising:

a main housing for accommodating components used in the coil unit, and an auxiliary housing for accommodating a cylindrical high-voltage tower protruding from the main housing to a front end side in an axial direction, and

a cylindrical coupling unit fitted to an outer circumferential surface of the cylindrical high-voltage tower while extending in an axial direction thereof to couple the coil unit to a spark plug,

the cartridge coupling unit includes:

an attachment portion which closely contacts the cover, an

A neck portion located on a leading end side with respect to the attachment portion,

wherein the neck portion is at least partially provided inside an open end of the plug hole on a base end side in the axial direction,

wherein the neck is formed by narrowing the sealing section radially inwards.

8. The ignition system of claim 7, wherein the coupling unit comprises:

a flexible seal section fitted to the outer peripheral surface of the high pressure column, the seal section including a first fitting section at a leading end of the seal section; and

a joint harder than the sealing section, the joint having a second fitting section fitted to the first fitting section,

wherein the neck is formed in the sealing section at least between the attachment portion and the joint in the axial direction.

9. The ignition system of claim 8, wherein the fitting section is cylindrical and comprises:

an inner peripheral step that is inclined radially outward as the inner periphery extends to the base end side in the axial direction; and

a base end inner peripheral surface extending from one end of the inner peripheral step to a base end side in the axial direction,

wherein a cavity is formed at least between the inner peripheral step or the base end inner peripheral surface and the sealing section.

10. The ignition system of claim 7, wherein the high pressure column includes a retaining portion to prevent removal of the coupling unit, the retaining portion protruding radially outward;

wherein the coupling unit includes a recess for receiving the holding portion,

wherein the neck portion is located at a position overlapping with the recess portion in a radial direction.

11. The ignition system according to claim 7, wherein the coupling section includes a convex portion on an outer peripheral surface thereof, the convex portion extending radially outward at a position adjacent to a front end side in the axial direction with respect to the neck portion.

12. The ignition system of claim 7, wherein the neck has a prescribed length in the axial direction.

13. The ignition system of claim 7, wherein the coupling unit includes a minimum diameter at the neck.

Technical Field

Embodiments of the present disclosure relate to an ignition coil unit and an ignition system for use in an internal combustion engine.

Background

As discussed in japanese patent application laid-open No.2009-281272(JP-2009-281272-a), there is known an ignition coil unit including a coil body for generating a high voltage and a cylindrical coupling unit for coupling the coil body to a spark plug. The coil body includes a primary coil, a secondary coil, and a main case accommodating the coils. The coil body further includes an auxiliary housing to accommodate a high tension tower (high tension tower) protruding from the main housing. The coupling unit includes a sealing section made of rubber fitted to the high-pressure column and a joint made of resin fitted to a notch of the sealing section.

Such a conventional ignition coil unit used in an internal combustion engine is sometimes mounted on an engine block including a cylinder head and a head cover covering the cylinder head. The cylinder head includes a plug hole, and the head cover includes an open hole facing the plug hole. The cover is disposed such that the open aperture is coaxial with the plug aperture. The ignition coil unit is inserted through the open hole and the plug hole.

However, in such an engine block, axial misalignment may occur such that the axis of the opening hole of the head cover is misaligned with the axis of the plug hole due to an allowable assembly tolerance when assembling the cylinder head and the head cover or a dimensional tolerance of the cylinder head or the head cover. When the ignition coil unit is mounted on the engine block with such an axial displacement, the area of the seal section between the open hole of the head cover and the plug hole of the cylinder head is deformed. Due to this deformation, the sealing section presses against the corners of the open end of the receptacle, possibly losing durability.

Various embodiments of the present disclosure have been made in view of the above-mentioned problems, and an object of one of the embodiments is to provide a novel ignition coil unit and an ignition system for use in an internal combustion engine, which are capable of suppressing or reducing interference between a seal section and an open end of a plug hole.

Disclosure of Invention

Accordingly, one aspect of the present disclosure provides a novel ignition coil unit attached to an engine block for an internal combustion engine. The engine body includes a cylinder head having a plug hole, and a head cover having an open hole facing the plug hole to cover the cylinder head. The ignition coil unit includes a coil body for generating a high voltage and a cylindrical coupling unit for coupling the coil body to a spark plug. The coil body includes: a main housing accommodating components of the coil body; and a housing that accommodates a cylindrical high-pressure column protruding from the main housing in an axial direction thereof. The coupling unit is constituted by a flexible sealing section fitted to the outer peripheral surface of the high-pressure column and a joint harder than the sealing section. The joint includes a joint fitting section that is fitted to a front end fitting section formed at a front end of the seal section. The sealing section comprises an attachment portion, otherwise known as a sealing portion, for tight contact with the cover, i.e. at the opening hole. The sealing section includes a neck portion in the Z-axis direction at least between the attachment portion and the joint. The neck portion is prepared by contracting the outer peripheral surface toward the inner peripheral surface.

Another aspect of the present invention provides a novel ignition system comprising: a cylinder head having a plug hole; a head cover covering the cylinder head by including an open hole facing the plug hole; and an ignition coil unit inserted into both the plug hole and the open hole. The ignition coil unit includes: a coil body generating a high voltage; and a cylindrical coupling unit that couples the coil body to the spark plug. The coil body includes: a main housing accommodating components included in the coil body; and a housing that accommodates a cylindrical high-pressure column protruding from the main housing in an axial direction thereof. The coupling unit is fitted to an outer peripheral surface of the high-pressure column. The coupling unit includes: an attachment portion that closely contacts the cover (i.e., at the opening hole); and a neck portion located inside the plug hole, at least partially facing the open end on the base end side at a position closer to the leading end thereof than the attachment portion. The outer peripheral surface of the neck portion is recessed toward the inner peripheral surface.

Exemplary advantages of each embodiment of the present disclosure are now described below. The sealing section included in the ignition coil unit of the first embodiment of the present disclosure includes an attachment portion to closely contact the cover. A joint that is harder than the seal section is located in the forward end fitting section of the seal section. Therefore, when the ignition coil unit is attached to the engine body and axial misalignment occurs therein between the open hole and the plug hole of the cover, axial misalignment may also occur between the high-voltage tower and the joint. That is to say, the high-pressure mast is guided and positioned by the open bore of the cover cap via the attachment in the sealing section which is fitted to the cover cap. In this way, the central axis of the high pressure column is intended to be aligned with the central axis of the opening hole of the cover hood. In another aspect, the tab located in the receptacle is guided and positioned by the receptacle. Thereby, the central axis of the connector is intended to be aligned with the central axis of the tap hole. As a result, the high pressure column and the joint are axially misaligned. Thus, the area between the attachment portion and the joint is deformed in the sealing section due to the axial misalignment between the high pressure column and the joint.

In view of this, in this embodiment of the disclosure, the sealing section comprises a neck portion, wherein at least the outer circumferential surface is recessed in the axial direction in a region between the attachment portion and the joint. That is, as described above, the neck is provided in a portion of the seal section, which may be deformed due to axial misalignment between the open hole of the cap and the tap hole. Therefore, even if axial misalignment occurs between the opening hole of the cover and the tap hole, the sealing section is prevented from interfering with the opening end of the tap hole.

Further, in the ignition system of the second aspect of the present disclosure, the coupling unit includes a neck portion located inside the plug hole at least at the open end on the base end side. Therefore, even if axial misalignment occurs between the opening hole of the cover and the tap hole, the coupling unit is prevented from interfering with the opening end of the tap hole.

Therefore, as described above, according to the above-described embodiments of the present disclosure, the ignition coil unit and the ignition system used in the internal combustion engine rarely interfere with the open end of the plug hole.

Drawings

A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

fig. 1 is a partial cross-sectional front view showing an exemplary ignition coil unit according to a first embodiment of the present disclosure;

FIG. 2 is an enlarged view showing the neck portion shown in FIG. 1 and its surroundings;

fig. 3 is a partially sectional exploded front view showing an ignition coil unit according to a first embodiment of the present disclosure;

fig. 4 is a partial cross-sectional front view showing an ignition system employing an ignition coil unit of a first embodiment of the present disclosure;

FIG. 5 is a partial cross-sectional elevation view showing an ignition system of a comparative example of the present disclosure, with the open hole of the cover cap coaxial with the plug hole;

FIG. 6 is also a partial cross-sectional elevation view showing an ignition system of a comparative example of the present disclosure, with the cover open holes being misaligned with the plug holes;

fig. 7 is a partial sectional front view showing an ignition coil unit according to a second embodiment of the present disclosure;

fig. 8 is a partial sectional front view showing an ignition coil unit according to a third embodiment of the present disclosure;

fig. 9 is a partial sectional front view showing an ignition coil unit according to a fourth embodiment of the present disclosure;

fig. 10 is a partial sectional front view showing an ignition coil unit according to a fifth embodiment of the present disclosure;

fig. 11 is a horizontal cross-sectional view showing a convex portion formed perpendicularly to a central axis in a fifth embodiment according to the present disclosure;

fig. 12 is a partially sectional front view showing an ignition coil unit constituted by an ignition coil unit of a fifth embodiment of the present disclosure;

fig. 13 is a cross-sectional view showing a modification of a convex portion formed in an ignition coil unit of a fifth embodiment of the present disclosure;

fig. 14 is a partial sectional front view showing an ignition coil unit according to a sixth embodiment of the present disclosure; and

fig. 15 is a partial sectional front view showing an ignition coil unit according to a seventh embodiment of the present disclosure.

Detailed Description

Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and particularly to fig. 1-4, an exemplary ignition coil unit for use in an internal combustion engine is described according to a first embodiment of the present disclosure.

As shown in fig. 4, the ignition coil unit 1 of this embodiment of the invention is attached to an engine unit 20 to be used. The engine unit 20 includes: a cylinder head 21, the cylinder head 21 including a plug hole 211; and a head cover 22 that covers the cylinder head 21 and has an opening hole 221 facing the plug hole 211.

As shown in fig. 1 and 3, the ignition coil unit 1 includes a coil unit 3 generating a high voltage and a cylinder coupling unit 4 coupling the coil unit 3 to a spark plug. The coil unit 3 includes a main housing 31 that accommodates various components of the coil unit 3, and a housing unit 30 that includes a high voltage tower 32. The high-voltage tower 32 is cylindrical and protrudes from the main casing 31 in the Z-axis direction to the front end side (of the ignition coil unit 1).

Furthermore, as shown in fig. 1 and 3, the cylinder coupling unit 4 is composed of a sealing section 5 and a joint 6. As shown in fig. 1, the sealing section 5 is flexible and fits on the outer peripheral surface of the high-pressure column 32. The sealing section 5 includes a front end fitting portion 521 at a front end thereof. The joint includes a joint fitting section 61 fitted to the front end fitting 521 of the seal section 5. The joint 6 is made of a harder material than the sealing section 5.

Further, as shown in fig. 1, 3 and 4, the sealing section 5 includes an attachment portion 41 that is in close contact with the cover 22. As shown in fig. 1 to 3, the sealing section 5 includes a neck portion 40, wherein an outer peripheral surface of the neck portion 40 is recessed toward an inner peripheral surface at least between the attachment portion 41 and the joint 6 in the Z-axis direction. More than two attachment portions 41 may be formed and employed as described later with reference to another embodiment of the present disclosure. In particular in this case. The sealing section 5 includes a neck 40 in the Z-axis direction at least between an attachment portion 41 provided at the topmost front end side and the joint 6.

Hereinafter, the ignition coil unit 1 according to one embodiment of the present disclosure is described in more detail, wherein a direction in which the central axis of the cylindrical high-voltage tower 32 extends is referred to as a Z-axis direction. The side of the joint 6 located with respect to the coil unit 3 in the axial direction Z is referred to as a leading end side. The side opposite to the tip side is referred to as the base side. Further, the radial direction of the high-pressure column 32 is simply referred to as the radial direction. Furthermore, in fig. 1 to 3, the respective central axes of the high-pressure column 32 and the joint 6 are indicated by a dash-dot line.

As shown in fig. 4, the ignition coil unit 1 of this embodiment of the present disclosure is connected to a spark plug mounted in a plug hole 211 of a cylinder head 21 mounted on an automobile or a cogeneration device (cogeneration) or the like to apply a high voltage to the spark plug. That is, the ignition coil unit 1 is attached to the engine unit 20 by inserting the coupling unit 4 (i.e., the seal section 5 and the joint 6) into both the opening hole 221 of the head cover 22 and the plug hole 211 of the cylinder head 21.

Although not shown, the coil unit 3 includes a primary coil and a secondary coil that are magnetically coupled to each other. The coil unit 3 is configured to control the secondary coil to generate a high voltage to ignite the spark plug by increasing or decreasing the amount of current flowing along the primary coil. The primary coil and the secondary coil are accommodated in a main housing 31 of the housing unit 30.

The housing unit 30 as a whole, i.e., the main housing 31 and the high-pressure column 32, is made of a resin such as a PBT (polybutylene terephthalate) resin. The main case 31 is a case including an opening facing the base end side (in the ignition coil unit 1).

Also, although not shown, the main housing 31 is filled with a sealing resin such as epoxy resin or the like. Accordingly, various components, such as the primary coil, the secondary coil, and the like, placed in the main housing 31 are fixed by the sealing resin.

Further, as shown in fig. 1 and 3, a connector 311 protruding perpendicular to the Z-axis direction is provided in the main housing 31. When one end of a cable connected to an external device, such as an ECU (i.e., an engine control unit) or the like, at the other end of the cable (i.e., an external connector) is connected to the connector 311, the connector 311 connects the ignition coil unit 1 with the external device. In addition, a high-voltage tower 32 is provided, and the high-voltage tower 32 protrudes from the front end side wall of the main case 31 toward the front end side (in the ignition coil unit 1).

The high pressure column 32 is cylindrical with a through hole pointing in the Z-axis direction. As shown in fig. 1 and 3, the high-pressure tower 32 includes a base end cylindrical portion 321 located on the base end side thereof and a tip end cylindrical portion 322 formed on the tip end side opposite to the base end cylindrical portion 321. The base end cylinder portion 321 has an annular shape. The outer diameter of the base end cylindrical portion 321 is larger than the outer diameter of the leading end cylindrical portion 322.

The distal end cylinder portion 322 is formed from the center of the base end cylinder portion 321 as viewed from the distal end side in the Z-axis direction. As shown in fig. 2, a holding portion 322a that projects radially toward the outer peripheral surface of the seal section 5 is formed and located in the leading end cylinder portion 322 so as to hold the seal section 5 (i.e., prevent it from falling). As the holding portion 322a extends toward the base end side, the radial projection of the holding portion 322a toward the outer circumferential surface of the seal section 5 increases. The holding portion 322a is formed over the entire circumference of the high pressure tower 32. The holding portion 322a is located on the base end side of the joint 6 in the Z-axis direction. Further, the sealing section 5 is positioned to completely cover the high pressure tower 32 from the outer circumferential surface of the high pressure tower 32.

Furthermore, the sealing section 5 is made of rubber. As shown in fig. 1, the seal section 5 includes a base end seal portion 51 fitted to a base end cylindrical portion 321 of the high-pressure tower 32. The seal section 5 also includes a front end seal portion 52 fitted to the front end cylinder portion 322.

Further, as shown in fig. 1 and 3, the base end of the base end seal portion 51 includes an expanded portion 511 expanded outward in the radial direction. As shown in fig. 1, the base end of the expanded portion 511 is in close contact with the front end side surface of the main casing 31.

Further, as shown in fig. 1 and 3, the expanded portion 511 includes an extended portion 512 extending toward the front end side at its outer peripheral edge. Therefore, as shown in fig. 4, when the ignition coil unit 1 is attached to the engine unit 20, the extension 512 closely contacts the entire circumference of the surrounding portion of the open hole 221 of the cover 22. Thereby, the expanded portion 511 seals the gap between the housing unit 30 and the cover 22. That is, the extension portion 512 constitutes the attachment portion 41 of the seal section 5.

Further, as shown in fig. 1 to 3, a lip 513 protruding radially outward is formed at the front end of the base end seal portion 51. When assembled and viewed in the radial direction, the lip 513 is positioned to overlap with the front section of the base end tubular portion 321 of the high-pressure tower 32.

Therefore, as shown in fig. 4, when the ignition coil unit 1 is attached to the engine unit 20, the lip 513 is in close contact with the entire inner peripheral surface of the opening hole 221 of the cover 22. In particular, the lip 513 also constitutes the above-mentioned attachment portion 41 of the sealing section 5, similarly to the extension portion 512. Further, the base end cylindrical portion 321 of the high-pressure tower 32 is pressed against the opening hole 221 of the cylinder head 21 in the radial direction by the lip 513. Thus, the high-pressure column 32 becomes coaxial with the open hole 221. That is, the center axis of the high-pressure tower 32 is aligned with the center axis L2 of the opening hole 221 of the head cover 22. Therefore, the area on the leading end side of the lip 513 in the seal section 5 is equal to the leading end seal portion 52.

As shown in fig. 4, when the ignition coil unit 1 is attached to the engine block 20, the front-end seal portion 52 of the seal section 5 is partially located inside the plug hole 211 (in the Z-axis direction). Therefore, the maximum diameter of a portion of the leading end sealing portion 52 located inside the nozzle hole 211 is almost equal to the diameter of the nozzle hole 211 where the leading end sealing portion 52 is located (in the Z-axis direction).

Further, as shown in fig. 2, the front end seal portion 52 includes a recessed portion 522 on an inner peripheral surface thereof to accommodate the holding portion 322a of the high pressure tower 32. The recess 522 has a shape corresponding to the contour of the holding portion 322 a. Specifically, the recess 522 increases in radially outward projection as it extends toward the base end side. The recess 522 is located on the base end side of the joint 6 in the Z-axis direction.

Further, as shown in fig. 2, the neck portion 40 is formed at a position of the seal section 5 where the seal section 5 overlaps with the recess 522 when viewed in the radial direction. Thus, the region of the seal section 5 (in the Z-axis direction) where both the neck portion 40 and the recessed portion 522 are formed is formed thinner than both the upper and lower adjacent regions in the Z-axis direction.

As shown in fig. 2, the diameter of the neck 40 is smaller than the diameter of the surrounding portion of the neck 40 in the sealing section 5. In addition, the outer diameter of the neck 40 is smaller than the outer diameter of the outer periphery of the projection 613 of the joint 6, which will be described below. Further, in this embodiment of the present disclosure, the outer diameter of the neck portion 40 is smaller than the outer diameter of the entire region of the seal section 5 on the front end side of the neck portion 40. In this embodiment of the present disclosure, the outer diameter of the neck 40 is smallest in the sealing section 5.

As shown in fig. 2, the neck portion 40 is formed continuously in the Z-axis direction from the leading end of the lip portion 513 to a position slightly on the leading end side with respect to the base end of the joint 6. That is, the front end of the neck 40 overlaps the joint 6 in the radial direction. The neck 40 has a predetermined length in the Z-axis direction. As shown in fig. 2, the neck portion 40 is formed continuously in the Z-axis direction from the front end position of the lip portion 513 to a position slightly on the front end side with respect to the base end of the joint 6. I.e. the front end 40 of the neck overlaps the joint 6 in the radial direction. That is, in this embodiment of the present disclosure, the neck 40 is not formed locally in the Z-axis direction, but has a prescribed length in the Z-axis direction so as to easily absorb the axial misalignment that occurs between the high-pressure column 32 and the joint 6. Furthermore, the neck 40 extends continuously over the circumference of the sealing section 5.

Further, as shown in fig. 1 to 3, a front end fitting 521 is formed at the front end of the seal section 5, to which the joint fitting section 61 of the joint 6 is fitted. That is, the joint fitting section 61 is inserted and fitted into the front end fitting portion 521.

Further, as shown in fig. 2, the front end fitting portion 521 includes an outer circumferential fitting portion 521a that covers the joint fitting section 61 from the outer circumference and an inner circumferential fitting portion 521b that covers the joint fitting section 61 from the inner circumference. As shown, the front end surface of the outer peripheral fitting portion 521a contacts the ring 611 included in the joint 6. The ring 611 projects radially outward, as described in more detail below. However, the outer circumferential fitting portion 521a may not contact the ring 611. The inner peripheral fitting portion 521b extends almost along the outer peripheral surface of the high-pressure tower 32.

Here, the joint 6 is made of PPS (polyphenylene sulfide resin) and is harder than the seal section 5 made of rubber. As shown in fig. 2, the joint fitting section 61 includes a ring 611 that contacts the leading end surface of the outer peripheral fitting portion 521a, and a cylindrical insertion portion 612 that is formed inside the leading end fitting portion 521 on the base end side of the ring 611.

As shown in fig. 4, when the ignition coil unit 1 is attached to the engine unit 20, the outer diameter of the ring 611 is almost equal to the outer diameter of the plug hole 211.

Further, as shown in fig. 2, the insertion portion 612 includes two (cylindrical) protruding portions 613 extending radially outward at two corresponding positions in the Z-axis direction. Each of the projections 613 increasingly extends radially outward as it extends toward the front end side. Each of the projections 613 serves to prevent the joint 6 from falling off from the front end fitting portion 521 of the seal segment 5.

As shown in fig. 2, on the inner peripheral surface of the insertion portion 612, a leading end inner peripheral surface 612a, an inner peripheral step 612b, and a base end inner peripheral surface 612c are formed in this order from the leading end side. The front end inner peripheral surface 612a is cylindrical and extends linearly in the Z-axis direction. The inner peripheral step 612b extends from one end of the leading inner peripheral surface 612a to the base end side. The inner peripheral step 612b gradually inclines radially outward as the inner peripheral step 612b extends toward the base end side in the Z-axis direction. The base end inner peripheral surface 612c extends from one end of the inner peripheral step 612b to the base end side in the Z-axis direction. The inner peripheral step 612b is positioned substantially at the center of the insertion portion 612 in the Z-axis direction.

Further, a cavity c is formed in the radial direction between each of the inner peripheral step 612b and the base end inner peripheral surface 612c and the inner peripheral fitting portion 521b of the seal section 5. In this embodiment of the present disclosure, the outer peripheral surface of the inner peripheral fitting portion 521b of the seal segment 5 extends almost in the Z-axis direction. Therefore, the front end of the inner peripheral fitting part 521b closely contacts the front end inner peripheral surface 612 a. On the other hand, a cavity c is formed between a portion on the base end side of the inner peripheral fitting portion 521b and each of the inner peripheral step 612b and the base end inner peripheral surface 612 c. The length of cavity c in the Z-axis direction is about half of insert 612.

Although not shown, the high-voltage terminal is press-fitted into the base end of the through-hole of the high-voltage tower 32. The high-voltage terminal is connected to the high-voltage side of the secondary coil and serves as an output terminal of the coil unit 3. The high-voltage terminal seals the through hole of the high-voltage tower 32 and also serves as a plug so that the sealing resin filled in the main case 31 does not leak from the high-voltage tower 32.

Further, as shown in fig. 1 and 2, an elastic conductive coil spring 7 deformable in the Z-axis direction is located inside the contact 6 and the high voltage tower 32. The coil spring 7 elastically contacts the high-voltage terminal located inside the high-voltage tower 32. Although not shown in the drawings, the coil spring 7 is positioned relative to the joint 6 in the Z-axis direction.

Further, as shown in fig. 1, the coupling unit 4 includes a plug cap 8 made of rubber, which is fitted to the front end of the joint 6. The spark plug is fitted into the front end side of the plug cap 8.

Now, an ignition system 2 including an ignition coil unit for use in an internal combustion engine according to another embodiment of the present disclosure will be described with reference to fig. 4.

The ignition system 2 of this embodiment includes an ignition coil unit 1 and an engine unit 20 having a cylinder head 21 and a head cover. The cylinder head 21 includes a plug hole 211. The head cover 22 covers the cylinder head 21 and includes an open hole 221 facing the plug hole 211. The ignition coil unit 1 is inserted into the plug hole 211 and the opening hole 221.

Generally, the head cover 22 and the cylinder head 21 are designed such that the center axis L2 of the opening hole 221 of the head cover 22 is aligned with the center axis L1 of the plug hole 211 of the cylinder head 21. However, the cylinder head 21 and the head cover 22 are sometimes manufactured to cause misalignment between the center axes of the plug hole 211 and the open hole 221 due to assembly tolerances of the cylinder head 21 and the head cover 22, dimensional tolerances of the cylinder head 21 and the head cover 22, and the like. Therefore, this embodiment is described based on the ignition unit 2 when the plug hole 211 of the cylinder head 21 and the opening hole 221 of the head cover 22 are misaligned with each other.

Hereinafter, the axial misalignment direction between the plug hole 211 and the opening hole 221 of the cover 22 when viewed from the Z-axis direction is hereinafter referred to as direction X. In the direction X, a side on which the central axis L2 of the cover 22 is located with respect to the central axis L1 of the tap hole 211 is hereinafter referred to as an X1 side. Further, when the center axis L2 of the opening hole 221 of the cover 22 is aligned with the center axis L1 of the plug hole 211, the outline of the ignition coil unit 1 is shown by the two-dot chain line.

Specifically, the plug hole 211 of the cylinder head 21 is open on the base end side. Although not shown, a female screw hole is provided and formed at the front end of the tap hole 211. The spark plug is screwed to the female hole and attached to the plug hole 211.

Further, the opening hole 221 formed in the cover 22 is slightly larger in size than the plug hole 211. A positioning portion 222, which is a protrusion, is formed on the base end side in the Z-axis direction at a position adjacent to the opening hole 221 of the cover 22. The positioning portion 222 (i.e., the protruding portion) is constituted by a ring extending over the entire circumference of the open hole 221.

Further, the ignition coil unit 1 is inserted into the opening hole 221 and the plug hole 211 of the cover 22. More specifically, the ignition coil unit 1 is inserted into the opening hole 221 and the plug hole 211 of the cover 22, with the extension portion 512 of the seal section 5 almost covering the positioning portion 222 in both the X and D directions.

Further, the lip 513 included in the seal section 5 of the ignition coil unit 1 pressure-contacts the inner peripheral surface of the opening hole 221 of the cover 22. In this way, the base end cylindrical portion 321 of the high-pressure tower 32 can be brought into pressure contact with the head cover 22 via the lip portion 513. Meanwhile, the center axis of the high pressure column 32 may be aligned with the center axis L2 of the opening hole 221 of the head cover 22.

Further, the neck 40 is partially located inside the open end 211a of the tap hole 211. Specifically, the neck 40 is positioned to partially overlap the open end 211a of the tap hole 211 in the radial direction. In this embodiment of the present disclosure, a recess 522 that receives the retaining portion 322a, which retains the high-pressure column 32, is formed on the inner peripheral surface of the seal section 5 and on the base end side of the plug hole 211.

Therefore, in this embodiment of the present disclosure, due to the axial misalignment between the tap hole 211 and the open hole 221, the region between the lip 513 of the seal section 5 and the leading end fitting 521 is more inclined toward the X1 side as it extends toward the base end side. Thus, when compared with a case where the center axes of the tap hole 211 and the opening hole 221 are aligned with each other (i.e., a case shown by the two-dot chain line in fig. 4), the portion of the sealing section 5 on the X1 side approaches the opening of the tap hole 211 on the base end side. However, since the position of the neck 40 faces the inner peripheral surface of the open end 211a of the plug hole 211 on the base end side, the sealing section 5 is prevented from contacting the opening of the plug hole 211 on the base end side.

Now, advantages obtained in one embodiment of the present disclosure are described below. In the ignition coil unit 1 of one embodiment of the present disclosure, the seal section 5 includes the attachment portion 41 that is in close contact with the cap 22. Furthermore, a joint 6 that is harder than the sealing section 5 is located in the front end fitting 521 of the sealing section 5. Therefore, the ignition coil unit 1 attached to the engine unit 20 with axial misalignment occurring between the open hole 221 of the cover 22 and the plug hole 211 can therefore generate axial misalignment between the high-voltage tower 32 and the joint. Therefore, the high-pressure column 32 is guided by the opening hole 221 of the head cover 22 via the attachment portion 41 of the seal section 5 fitted to the opening hole 221. As such, the center axis of the high-pressure column 32 is adjusted to be aligned with the center axis L2 of the opening hole 221 of the head cover 22. Further, the tab 6 located in the tap hole 211 is guided by the tap hole 211. Thereby, the center axis of the contact 6 is aligned with the center axis L1 of the tap hole 211. As a result, the high pressure column 32 and the joint 6 are axially misaligned together. As a result, the region between the attachment portion 41 and the joint 6 is deformed in the sealing section 5 due to the axial misalignment between the high-pressure mast 32 and the joint 6.

In view of this, according to this embodiment of the present disclosure, the sealing section 5 comprises a neck 40, wherein at least the outer surface is recessed in the Z-axis direction in the area between the attachment portion 41 and the joint 6. That is, as described above, the neck 40 is disposed in a portion of the seal section 5 deformed by the axial misalignment between the open hole 221 of the cap 22 and the plug hole 211. Therefore, even if axial misalignment occurs between the opening hole 221 of the cover 22 and the plug hole 211, the sealing section 5 can be prevented from interfering with the open end 211a of the plug hole 211.

Here, an ignition system 90 having the ignition coil unit 9 not including the neck portion is described with reference to fig. 5 and 6 as comparative examples. As shown in the drawing, the comparative example includes a configuration similar to one embodiment of the present disclosure except that the ignition coil unit 9 thereof does not include a neck portion. As shown in fig. 5, in the ignition system 90 of the comparative example, when no axial misalignment is generated between the opening hole 221 of the cover 22 and the plug hole 211, the seal section 5 does not press-contact the opening end 211a of the plug hole 211 on the base end side. In contrast, however, as shown in fig. 6, in the ignition system 90 of the comparative example, when the center axis L2 of the opening hole 221 of the cover 22 is located on the X1 side so as to be misaligned with the center axis L1 of the plug hole 211, a portion of the seal segment 5 located on the X1 side is pressure-contacted to the open end 211a of the plug hole 211 located on the base end side. As such, the sealing section 5 is not durable.

In contrast, as shown in fig. 4, since the sealing section 5 of this embodiment of the present disclosure includes the neck portion 40, the sealing section 5 can be prevented from interfering with the open end 211a of the tap hole 211.

Further, the neck portion 40 is located at a position overlapping with the recess 522 in the radial direction. Therefore, the portion of the seal section 5 forming both the neck 40 and the recess 522 is thinner than both sides thereof in the Z-axis direction. As a result, the sealing section 5 can easily ensure the flexibility of the neck 40. Therefore, when the ignition coil unit 1 is inserted into the engine unit 20 with axial misalignment occurring between the open hole 221 of the cover 22 and the plug hole 221, the ignition coil unit 1 can be easily and safely inserted and located at the engine unit 20 because the neck portion 40 of the ignition coil unit 1 is deformed in accordance with the axial misalignment between the open hole 221 of the cover 22 and the plug hole 211.

Further, since the neck portion 40 has a given length in the Z-axis direction, the neck portion 40 can be easily located radially inside the open end 211a of the plug hole 211 on the base end side when the ignition coil unit 1 is attached to the engine. As a result, the productivity of the ignition coil unit 1 can be effectively improved.

In addition, since the neck 40 provides the minimum diameter of the seal section 5, the outer circumferential surface of the neck 40 is recessed deeper to the inner circumferential side in the seal section 5. In this way, the interference between the neck 40 and the open end 211a of the plug hole 211 can be more effectively prevented. Further, as the outer diameter of the neck 40 becomes smaller, the thickness of the neck 40 can be easily thinned. Therefore, the flexibility of the neck 40 can be ensured. Therefore, when the ignition coil unit 1 is inserted into the engine unit 20 with axial misalignment occurring between the open hole 221 of the cover 22 and the plug hole 211 therein, the neck portion 40 of the ignition coil unit 1 is deformed in accordance with the axial misalignment between the open hole 221 of the cover 22 and the plug hole 211, so that the ignition coil unit 1 can be easily and safely inserted and finally positioned in the engine unit 20.

Further, a cavity c is formed in the radial direction between each of the base end inner peripheral surface 612c and the inner peripheral step 612 provided in the joint fitting section 61 and the seal section 5. Thus, the flexibility of the joint fitting section 61 and its surroundings in the sealing section 5 in the radial direction can be increased. Therefore, when the ignition coil unit 1 is inserted into the engine unit 20 and axial misalignment occurs therein between the opening hole 221 of the cover 22 and the plug hole 211, the joint fitting section 61 and its surrounding portion in the seal section 5 can be easily deformed according to the axial misalignment. As a result, the ignition coil unit 1 can be obtained that is easily and safely attached to the engine unit 20 that generates axial misalignment between the opening hole 211 and the plug hole 211 of the cover 22.

Further, according to another embodiment of the present disclosure, the neck portion 40 formed in the coupling unit 4 of the ignition system 2 is located at least partially radially inside of the open end 211a of the plug hole 211 on the base end side. Therefore, even when axial misalignment occurs between the opening hole 221 of the cover 22 and the plug hole 211, the coupling unit 4 can be prevented from interfering with the opening end 211a of the plug hole 211.

As described above, according to one embodiment of the present disclosure, an ignition coil unit and an ignition system for use in an internal combustion engine can be obtained that can avoid or reduce interference with the open end of the plug hole.

Now, a second embodiment of the present disclosure is described below with reference to fig. 7. As shown in fig. 7, the second embodiment of the present disclosure is a modification of the first embodiment of the present disclosure and is obtained by changing the shape of the joint fitting section 61 of the first embodiment.

In this embodiment of the present disclosure, the inner peripheral step 612b formed on the inner peripheral surface of the insertion portion 612 of the joint fitting section 61 is located on the front end side in the insertion portion 612. Thereby, the base end inner peripheral surface 612c of the joint fitting section 61 is longer than the leading end inner peripheral surface 612a in the Z-axis direction.

In addition, the inner peripheral fitting part 521b of the front end fitting part 521 of the seal section 5 closely contacts the front end inner peripheral surface 612a while forming a cavity c with each of the inner peripheral step 612b and the base end inner peripheral surface 612 c. Thus, cavity c is longer than half of insert 612 in the Z-axis direction.

The remaining sections and portions are substantially the same as those of the first embodiment of the present disclosure.

Thus, according to this embodiment of the present disclosure, the flexibility of the joint fitting section 61 and its surroundings in the sealing section 5 in the radial direction is further enhanced. Therefore, when the ignition coil unit 1 is inserted into the engine block with axial misalignment occurring therein between the open hole and the plug hole of the cover, then the joint fitting section 61 and its surrounding portion in the seal section 5 can be effectively deformed in accordance with the axial misalignment. Thereby, the ignition coil unit 1 more easily attached to the engine unit 20 that generates axial misalignment between the opening hole and the plug hole of the cover can be easily obtained. Further, the second embodiment of the present disclosure can obtain advantages similar to those of the first embodiment of the present disclosure.

Now, a third embodiment of the present disclosure is described below with reference to fig. 8. As shown, in this embodiment of the present disclosure, the sealing section 5 comprises a plurality of components. That is, in this embodiment of the present disclosure, the seal section 5 is configured by including a (cylindrical) base end seal portion 51 to cover the base end cylinder portion 321 of the high-pressure tower 32 and a (cylindrical) leading end seal portion 52 prepared separately from the base end seal portion 51 to cover the leading end cylinder portion 322 of the high-pressure tower 32.

More specifically, the neck portion 40 is formed in the base end of the base end seal portion 51 (the leading end seal portion 52). That is, the upper portion and the lower portion of the base end seal portion 51 (the leading end seal portion 52) that sandwich the neck portion 40 in the Z-axis direction protrude radially outward from the neck portion 40.

The remaining configuration is similar to that of the first embodiment of the present disclosure, and the description is not repeated. Also, the third embodiment of the present disclosure can obtain advantages similar to those of the first embodiment of the present disclosure.

Now, a fourth embodiment of the present disclosure is described below with reference to fig. 9. As shown in fig. 9, this embodiment of the present disclosure is a modification of the third embodiment, and the shape of the leading end seal portion 52 employed in the third embodiment is changed. That is, in this embodiment of the present disclosure, the neck portion 40 extends to the base end of the leading end seal portion 52. The remaining configuration is similar to that of the third embodiment of the present disclosure, and the description thereof will not be repeated. Therefore, the fourth embodiment of the present disclosure can obtain advantages similar to those of the third embodiment of the present disclosure again.

Now, a fifth embodiment of the present disclosure is described below with reference to fig. 10 to 12. As shown in fig. 10 to 12, the basic structure of this embodiment of the present disclosure is substantially the same as that of the first embodiment of the present disclosure. However, the seal section 5 includes a convex portion 53 extending radially outward from the outer peripheral surface of the seal section 5 at a position adjacent to the neck portion 40 on the leading end side. That is, as shown in fig. 10, the convex portion 53 extends radially outward from both sides of the seal segment 5 extending in the Z-axis direction. More specifically, in a cross section of the ignition coil unit 1 including the center axis of the high voltage tower 32 (i.e., parallel to the Z-axis direction), the convex portion 53 has a substantially arc shape expanding radially outward.

Further, as shown in fig. 11, a convex portion 53 is continuously formed on the periphery of the seal section 5. However, as shown in fig. 13, the convex portion 53 may be formed intermittently on the periphery of the seal section 5. Here, the remaining part of the projection 53 is not illustrated in fig. 11 and 13. Again, the remaining configuration is similar to that of the first embodiment of the present disclosure and is not repeated.

Therefore, according to this embodiment of the present disclosure, the sealing section 5 includes a convex portion 53 on an outer peripheral surface thereof, the convex portion 53 being adjacent to the neck portion 40 on a front end side with respect to the neck portion 40. Thereby, the neck portion 40 is relatively recessed from the convex portion 53 to some extent. Therefore, when the ignition coil unit 1 of this embodiment of the present disclosure is attached to the engine unit 20, which generates axial misalignment between the opening hole 221 of the cover 22 and the plug hole 211, as shown in fig. 12, the convex portion 53 contacts the inner peripheral surface of the plug hole 211. Therefore, the neck portion 40 deeply recessed radially inward from the convex portion 53 can be further effectively prevented from interfering with the open end 211a of the tap hole 211. Also, the remaining configuration is similar to that of the first embodiment of the present disclosure, and the description is not repeated.

Now, a sixth embodiment of the present disclosure is described below with reference to fig. 14. As shown in fig. 14, this embodiment of the present disclosure is a modification of the fifth embodiment of the present disclosure, and is prepared by changing the configuration of the convex portion 53 of the fifth embodiment. In this embodiment of the present disclosure, the projection 53 includes a given length in the Z-axis direction. Further, the convex portion 53 is formed at a position (e.g., height) overlapping with the joint fitting section 61 of the joint 6 in the radial direction. More specifically, in this embodiment of the present disclosure, the projection 53 is at a position overlapping in the radial direction with the protruding portion 613 formed in the insertion portion 612 of the joint fitting section 61 on the base end side. The remaining configuration described above is substantially the same as that of the fifth embodiment of the present disclosure, and the description is not repeated.

Therefore, according to this embodiment of the present disclosure, the convex portion 53 is formed at a position overlapping with the joint fitting section 61 in the radial direction. Therefore, the joint 6 can be easily prevented from falling off from the front end fitting portion 521 of the seal section 5. In addition to the above advantages of the fifth embodiment of the present invention, the present embodiment of the present disclosure may provide substantially the same advantages.

Now, a seventh embodiment of the present disclosure is described below with reference to fig. 15. As shown in fig. 15, this embodiment of the present disclosure is a modification of the first embodiment of the present disclosure, and is prepared by changing the configuration of the coupling unit 4 of the first embodiment. That is, in this embodiment of the present disclosure, the coupling unit 4 is entirely constituted by the sealing section 5. More specifically, the base end of the seal section 5 is fitted to the high-voltage tower 32 and the leading end side of the seal section 5 receives an inserted spark plug.

The remaining configuration described above is substantially the same as that of the first embodiment of the present disclosure, and the description is not repeated. This embodiment of the present disclosure may provide substantially the same advantages, in addition to the advantages described above as the first embodiment of the present disclosure.

The present disclosure is not limited to the above-described embodiments. For example, the neck 40 employed in each of the above-described embodiments may be inclined upward in the Z-axis direction to the middle portion thereof by gradually reducing the diameter of the neck 40 in the direction X as the neck 40 extends to the middle portion thereof in the Z-axis direction. Further, the outer peripheral surface of the coupling unit 4 may be recessed stepwise to exclude a slope in the Z-axis direction therefrom.