JP2023040900A - internal combustion engine - Google Patents

Abstract

To reduce the sizes of a cap and a plug hole for mounting an ignition plug to a cylinder head in an internal combustion engine including the cap in which an auxiliary chamber accommodating a center electrode and a ground electrode is provided.SOLUTION: An internal combustion engine 1 includes: an ignition plug 2 mounted to a cylinder head 6 and having a center electrode 21 and a ground electrode 22; a cap 3 that is interposed between the ignition plug 2 and the cylinder head 6 and has a flange 31 and in which an auxiliary chamber 3s accommodating the center electrode 21 and the ground electrode 22 and communicated with a main chamber 71 of a combustion chamber 7 is provided; and a first seal member 4 disposed between the flange 31 of the cap 3 and the ignition plug 2. A projecting part 31x for receiving a tool to be used when the cap 3 is mounted to the cylinder head 6 and an annular projection 311 abutting on the seal member 4 are provided on an upper surface 31a of the flange 31 of the cap 3.SELECTED DRAWING: Figure 1

Description

The present invention relates to a spark ignition internal combustion engine.

Conventionally, in a spark-ignited internal combustion engine, it has been considered to use a cap internally provided with a pre-chamber containing a center electrode and a ground electrode of a spark plug in order to make the propagation speed of combustion appropriate. (See, for example, Patent Document 1).

In the configuration described in Patent Document 1, after the air-fuel mixture is ignited in the pre-chamber, the combustion is propagated from the pre-chamber to the combustion chamber through a communication hole provided in the cap.

JP 2014-159778 A

By the way, in order to attach the spark plug and the cap as disclosed in Patent Document 1 to the cylinder head, it is necessary to attach the cap to the cylinder head using a jig. Therefore, there arises a problem that the cap becomes large due to the need to secure a space for mounting the jig.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the size of an internal combustion engine having a cap with a pre-chamber for accommodating a center electrode and a ground electrode.

In order to solve the above-described problems, the present invention provides a spark plug attached to a cylinder head and having a center electrode and a ground electrode, and a center electrode of the spark plug having a flange interposed between the spark plug and the cylinder head. and a cap internally provided with a sub-chamber that houses a ground electrode and communicates with the combustion chamber; and a sealing member arranged between the flange of the cap and the spark plug. The internal combustion engine is provided with a recess for receiving a tool used when attaching the cap to the head, and an annular protrusion that abuts against the seal member.

According to the present invention, in a spark plug having a cap internally provided with a pre-chamber for accommodating a center electrode and a ground electrode, it is possible to reduce the size of such a cap.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows the principal part of the internal combustion engine which concerns on one Embodiment of this invention. The perspective view which shows the upper half part of the cap which concerns on the same embodiment. The perspective view which shows the jig|tool which concerns on the same embodiment. The perspective view which shows the attachment body 690 of the cap which concerns on the same embodiment.

An embodiment of the invention is described below with reference to FIGS. 1-4.

The internal combustion engine 1 according to the present embodiment is a port-injection and spark-ignition four-stroke engine that injects fuel such as gasoline or hydrogen into an intake port (not shown) and introduces an air-fuel mixture into a combustion chamber. 2, the spark plug 2, the cap 3 interposed between the spark plug 2 and the cylinder head 6 and having the flange 31 at the top, more precisely, at the top end, the upper surface 31a of the flange 31 of the cap 3 and the spark plug 2 and a second sealing member 5 arranged between the lower surface 31 b of the cap flange 31 and the upper surface 6 a of the cylinder head 6 . 6w is a water jacket.

The spark plug 2 is a conventional one that is attached to the cylinder head 6 and has a center electrode 21 and a ground electrode 22 . Although FIG. 1 shows the spark plug 2 as a whole, insulation is provided between the center electrode 21 and the ground electrode 22 .

The cap 3 is interposed between the spark plug 2 and the cylinder head 6 as described above, can be assembled to the cylinder head 6 independently of the spark plug 2, and has a flange 31 on its top. When the cap 3 is attached to the cylinder head 6, the first sealing member 4 is interposed between the upper surface 31a of the flange 31 and the spark plug 2, and the lower surface 31b of the flange 31 and the upper surface 6a of the cylinder head 6 are connected. A second sealing member 5 is interposed between them. Both the first and second sealing members 4 and 5 are gaskets made of a member having a hardness lower than that of the cap 3 . However, other sealing materials may be used instead of gaskets.

As shown in FIG. 1, the outer surface 3a of the cap 3 is provided with a male thread 3a1, and the inner surface 3b thereof is provided with a female thread 3b1 for mounting the spark plug 2 thereon. The male screw 3a1 and the female screw 3b1 are displaced in the axial direction, that is, in the vertical direction. The male screw 3a1 is screwed into the female screw 6h1 formed in the plug mounting hole 6h of the cylinder head 6 to mount the cap 3 on the plug mounting hole 6h of the cylinder head 6. A male thread 2a1 formed on the outer surface 2a of the spark plug 2 is screwed into a female thread 3b1 of the cap 3b, and the spark plug 2 is mounted in a spark plug housing hole 3h formed inside the cap 3. As shown in FIG.

Further, the cap 3 is internally provided with an auxiliary chamber 3s for accommodating the center electrode 21 and the ground electrode 22 of the spark plug 2. As shown in FIG. The auxiliary chamber 3s communicates with the main chamber 71 of the combustion chamber 7 via a hole 3s1. In other words, as shown in FIG. 1, and as described above, the cap 3 is attached to the plug mounting hole of the cylinder head 6 with the spark plug 2 mounted in the spark plug housing hole 3h formed inside the cap. 6h, and in the state where the spark plug 2 is installed, a sub-chamber 3s communicating with the main chamber 71 of the combustion chamber 7 is formed at the bottom thereof while containing the center electrode 21 and the ground electrode 22. It's becoming In this embodiment, the air-fuel mixture is introduced into the pre-chamber 3s and is spark ignited, and the air-fuel mixture ignited in the pre-chamber 3s is introduced into the main chamber 71 through the holes 3s1, and combustion propagates. ing.

In this embodiment, as shown in FIGS. 1 and 2, the outer peripheral portion of the upper surface 31a of the flange 31 receives a jig J which is a tool used when attaching the cap 3 to the cylinder head 6. are formed with a plurality of recesses 31x. The recesses 31x are formed at four locations at intervals of 90 degrees in this embodiment. More specifically, the cap 31 is screwed onto the cylinder head 6 using a jig J as shown in FIG. The jig J has a projection J1 at its distal end that can be engaged with the recess 31x of the cap 3, and a projection J2 at its proximal end that engages with a tool such as a box wrench (not shown) to receive an operating force. A chamfer 31y is applied to the opening edge of the recess 31x.

In addition, as shown in FIGS. 1 and 2, an annular protrusion 311 is provided on the upper surface 31a of the flange 31 between the recess 31x and the spark plug housing hole 3h. ing.

As shown in FIG. 4, the cap 3 according to the present embodiment is attached to the cylinder head 6 by inserting the male screw 3a1 into the plug while the projection J1 of the jig J is engaged with the recess 31x of the upper surface 31a of the flange 31. This is done by screwing it into the internal thread 6h1 of the hole 6h. After that, the ignition plug 2 is attached to the cap 3 by screwing the male thread 2a1 formed on the outer surface 2a of the ignition plug 2 into the female thread 3b1 of the cap 3. As shown in FIG. Here, when the cap 3 is attached to the cylinder head 6 and the spark plug 2 is attached to the cap 3, as shown in FIG. is sealed, thus isolating between the combustion chamber 7 and the space above the cylinder head 6 . Further, the tip of the annular projection 311 provided on the upper surface 31a of the flange 31 of the cap 3 is in linear contact with the first seal member 4, and the axial force generated when the spark plug 2 is screwed to the cap 3 causes an annular The protrusion 311 is pressed against the first sealing member 4 so that the space between the flange 31 of the cap 3 and the spark plug 2 is sealed.

As described above, according to the configuration of this embodiment, since the upper surface 31a of the flange 31 of the cap 3 is provided with the recess 31x for receiving (the protrusion J1 of) the jig J, the diameter of the jig can be reduced. It can be accommodated within the diameter of the cap 3.

In addition, since the upper surface 31a of the flange 31 of the cap 3 is provided with an annular protrusion 311 that contacts the first seal member 4, the axial force when the spark plug 2 is screwed to the cap 3 is reduced by the first seal member. 4, and the sealing between the spark plug 2 and the cap 3 can be performed more effectively.

Furthermore, since the edge of the opening of the recess 31x is chamfered 31y, it is possible to suppress the occurrence of burrs on the edge of the opening of the recess 31x.

In addition, since the second seal member 5 is arranged between the lower surface 31b of the flange 31 of the cap 3 and the upper surface 6a of the cylinder head 6, the cylinder head 6 is sandwiched by the seal member 5 and the combustion chamber 7 side is compressed. and the other side.

In addition, in the cap 3, the male thread 3a1 provided on the outer surface 3a for attachment to the plug mounting hole 6h of the cylinder head 6 and the female thread 3b1 provided on the inner surface 3b for attachment of the spark plug 2 are displaced. Therefore, it is not necessary to make the cap 3 thick in order to simultaneously provide male and female threads on both the inner and outer surfaces of the cap 3 while ensuring the strength of the cap 3. It is also possible to reduce the weight of the device itself.

In addition, this invention is not limited to embodiment described above.

For example, any number and shape of recesses may be provided in the flange of the cap to receive a tool used to attach the cap to the cylinder head.

Also, any tool may be used for attaching the cap to the cylinder head.

In addition, the seal between the spark plug and the cap and the seal between the cap and the cylinder head may employ various configurations other than those using low-hardness seal members as in the above-described embodiment. Of course it is. Further, the shape of the tip of the annular projection provided on the upper surface of the flange of the cap and abutting against the sealing member is not limited to the triangular shape as shown in the illustrated example, but may be set arbitrarily to a semicircular shape.

The flange formed on the cap is preferably provided at the upper end as in the above-described embodiment. It does not matter if it is set in place.

In addition, various modifications may be made within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1... Internal combustion engine 2... Spark plug 21... Center electrode 22... Ground electrode 3... Cap 31... Flange 31a... Upper surface of flange 31x... Recess 311... Annular projection 3s... Pre-chamber 4... (first) seal member 6... Cylinder head 7... Combustion chamber J... Tool (jig)

Claims (1)

a spark plug attached to the cylinder head and having a center electrode and a ground electrode;
a cap interposed between the spark plug and the cylinder head, having a flange, housing a center electrode and a ground electrode of the spark plug, and internally provided with a pre-chamber communicating with the combustion chamber;
An internal combustion engine comprising a sealing member arranged between the flange of the cap and the spark plug,
An internal combustion engine, wherein an upper surface of a flange of the cap is provided with a concave portion for receiving a tool used when attaching the cap to the cylinder head, and an annular projection that abuts against the seal member.

Images