JP7487595B2 - Spark plug for internal combustion engine and internal combustion engine - Google Patents

Description

The present invention relates to a spark plug for an internal combustion engine and an internal combustion engine.

A spark plug with a secondary combustion chamber that is configured to form a swirl flow in the secondary combustion chamber is disclosed in, for example, Patent Document 1.

DE 10 2018 211 009 A1

However, depending on the relationship between the position and orientation of the nozzle hole provided in the plug cover that forms the auxiliary combustion chamber and the position of the discharge gap, there may be disadvantages in terms of ignition. That is, when a mixture containing fuel flows from the main combustion chamber into the auxiliary combustion chamber through the nozzle hole, there is a concern that the strength of the air flow passing through the discharge gap may be insufficient, or the fuel density of the mixture supplied to the discharge gap may be insufficient, depending on the orientation of the nozzle hole, etc. There is also a concern that the discharge or initial flame formed in the discharge gap may be difficult to eject from the nozzle hole into the main combustion chamber. The spark plug described in Patent Document 1 does not take such points into consideration, and it can be said that there is room for improvement in ignition.

The present invention was made in consideration of these problems, and aims to provide a spark plug for an internal combustion engine with excellent ignition properties, and an internal combustion engine.

One aspect of the present invention is a cylindrical insulator (3),
a center electrode (4) held on the inner circumferential side of the insulator and protruding from the insulator toward the tip side;
a cylindrical housing (2) that holds the insulator on its inner periphery;
a ground electrode (6) forming a discharge gap (G) between itself and the center electrode;
a plug cover (5) provided at the tip of the housing so as to cover a sub-combustion chamber (50) in which the discharge gap is disposed,
The plug cover is formed with a nozzle hole (51) that communicates the auxiliary combustion chamber with the outside,
When viewed from the plug axial direction, the central axis of the injection hole is inclined with respect to the plug radial direction,
At least one of the nozzle holes is a gap-facing nozzle hole (510) in which an extension line (51L) of a central axis of the nozzle hole passes through the discharge gap,
In a spark plug (1) for an internal combustion engine, when a point where an extension line of a central axis of the gap opposed injection hole intersects with an inner surface of the pre-combustion chamber at a position different from that of the gap opposed injection hole is defined as point A1 and a distance from the gap opposed injection hole to point A1 is defined as L1, a distance (L2) from the gap opposed injection hole to the discharge gap is less than half of distance L1 .

Another aspect of the present invention is an internal combustion engine (10) including the above-mentioned spark plug for an internal combustion engine,
A main combustion chamber (11);
The spark plug is disposed so that an outer surface (52) of the plug cover faces the main combustion chamber;
an injector (71) for injecting fuel directly into the main combustion chamber;
The spark plug is in an internal combustion engine and is positioned such that an injection flow (F) containing the fuel injected from the injector during the compression stroke of the internal combustion engine is directed toward an outer opening (511) of the gap opposing nozzle hole.

In the spark plug for an internal combustion engine, the central axis of the nozzle hole is inclined relative to the plug radial direction when viewed from the plug axial direction. This allows a swirl flow to be formed in the auxiliary combustion chamber by the airflow introduced into the auxiliary combustion chamber through the nozzle hole, or the airflow flowing out of the auxiliary combustion chamber through the nozzle hole.

At least one of the nozzle holes is the gap-facing nozzle hole described above. When a fuel-containing mixture is introduced into the auxiliary combustion chamber from the gap-facing nozzle hole, the mixture flows toward the discharge gap, which makes it easier for the discharge to extend. Also, a mixture with a high fuel density is more likely to reach the discharge gap. This improves the ignition performance in the auxiliary combustion chamber, and ultimately improves the ignition performance in the main combustion chamber.

In addition, when a discharge is generated during the expansion stroke, the discharge generated in the discharge gap due to the airflow from the auxiliary combustion chamber toward the main combustion chamber tends to extend toward the gap-opposed nozzle, improving ignition performance in the auxiliary combustion chamber. In addition, since the ignition position can be easily brought closer to the gap-opposed nozzle, cold loss is suppressed and the flame jet to the main combustion chamber can be strengthened. Furthermore, since the discharge generated in the discharge gap or the initial flame is easily ejected from the gap-opposed nozzle, ignition performance in the main combustion chamber can be improved.

In the above internal combustion engine, the spark plug is positioned so that the injection flow containing fuel injected from the injector during the compression stroke is directed toward the outer opening of the gap opposed nozzle. This makes it easier for a high fuel density mixture to be introduced from the gap opposed nozzle into the auxiliary combustion chamber. As a result, the high fuel density mixture is more likely to reach the discharge gap, improving ignition performance.

As described above, according to the above aspect, it is possible to provide a spark plug for an internal combustion engine, which has excellent ignition properties, and an internal combustion engine.
In addition, the symbols in parentheses described in the claims and the means for solving the problems indicate a correspondence with the specific means described in the embodiments described below, and do not limit the technical scope of the present invention.

3 is a cross-sectional view taken along the line II in FIG. 2, showing a portion of the spark plug in the vicinity of its tip end in the axial direction according to the first embodiment; FIG. FIG. 2 is a view taken along the arrow II in FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2 . 1 is a cross-sectional explanatory diagram of an internal combustion engine according to a first embodiment. FIG. 4 is an explanatory diagram illustrating the direction of an injection flow relative to the spark plug in the first embodiment, as viewed from the plug axial direction. FIG. 11 is an axial cross-sectional view of a spark plug in the vicinity of a tip portion of the spark plug according to a second embodiment. FIG. 11 is an axial cross-sectional view of a spark plug in the vicinity of a tip portion of the spark plug according to a third embodiment. FIG. 11 is an axial cross-sectional view of a spark plug in the vicinity of a tip portion of the spark plug according to a fourth embodiment. FIG. 13 is an axial cross-sectional view of a spark plug in the vicinity of a tip portion of the spark plug according to a fifth embodiment.

(Embodiment 1)
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a spark plug for an internal combustion engine and an internal combustion engine will be described with reference to FIGS.
The spark plug of this embodiment, as shown in FIGS. 1 to 3, includes a cylindrical insulator 3, a center electrode 4, a cylindrical housing 2, a ground electrode 6, and a plug cover 5.

The center electrode 4 is held on the inner periphery of the insulator 3 and protrudes from the insulator 3 toward the tip side. The housing 2 holds the insulator 3 on the inner periphery. The ground electrode 6 forms a discharge gap G between the center electrode 4. The plug cover 5 is provided at the tip of the housing 2 so as to cover the auxiliary combustion chamber 50. The discharge gap G is arranged within the auxiliary combustion chamber 50.

The plug cover 5 is formed with a nozzle hole 51 that connects the auxiliary combustion chamber 50 to the outside. As shown in FIG. 2, the central axis of the nozzle hole 51 is inclined with respect to the plug radial direction when viewed from the plug axial direction Z. At least one nozzle hole 51 is a gap-opposed nozzle hole 510 described below. The gap-opposed nozzle hole 510 is a nozzle hole 51 in which an extension line 51L of the central axis of the nozzle hole passes through the discharge gap G, as shown in FIG. 1 and FIG. 2.

In other words, whether viewed from the plug radial direction as in FIG. 1 or from the plug axial direction Z as in FIG. 2, the extension line 51L of the central axis of the gap-facing injection hole 510 (hereinafter also referred to as the "injection hole axis 51L" as appropriate) passes through the discharge gap G.

The spark plug 1 of this embodiment can be used as an ignition means in internal combustion engines of automobiles, cogeneration systems, etc. As shown in FIG. 4, the mounting thread portion 24 formed on the outer peripheral surface of the housing 2 is screwed into the female thread portion of the plug hole 711, and the spark plug 1 is attached to the internal combustion engine 10. One end of the spark plug 1 in the axial direction Z is then placed in the main combustion chamber 11 of the internal combustion engine 10. In the axial direction Z of the spark plug 1, the side exposed to the main combustion chamber 11 is referred to as the tip side, and the opposite side is referred to as the base side. The axial direction Z of the spark plug 1 is also referred to as the plug axial direction Z, or simply the axial direction Z, as appropriate.

As shown in FIG. 1, the plug cover 5 is joined to the tip of the housing 2 by welding or the like. When the spark plug 1 is attached to the internal combustion engine, the plug cover 5 separates the auxiliary combustion chamber 50 from the main combustion chamber 11. In this embodiment, the plug cover 5 is formed with a plurality of injection holes 51. Each injection hole 51 is inclined so that it approaches the outer periphery as it approaches the tip.

During the compression stroke of the internal combustion engine, airflow is introduced from the main combustion chamber 11 to the auxiliary combustion chamber 50 through the injection hole 51. The injection hole 51 is formed so that the airflow introduced into the auxiliary combustion chamber 50 through the injection hole 51 generates a swirl flow (see dashed arrow A in FIG. 5) in the auxiliary combustion chamber 50. Specifically, as shown in FIG. 2, when the spark plug 1 is viewed from the axial direction Z, the injection hole 51 is formed in a state in which the injection hole axis 51L does not pass through the plug central axis PC. In this embodiment, the injection hole axis 51L does not pass through the center electrode 4. The plug central axis PC is the central axis of the spark plug 1, and in this embodiment, it is also the central axis of the center electrode 4.

When viewed from the axial direction Z, the injection hole axis 51L is inclined at an acute angle α with respect to an imaginary line VL that passes through the injection hole 51 and the plug center axis PC and extends in the plug radial direction. For the multiple injection holes 51, the inclination direction of the injection hole axis 51L with respect to the imaginary line VL for each injection hole 51 is on the same side in the plug circumferential direction. In this embodiment, the multiple injection holes 51 have the same angle α. The plug circumferential direction is the direction along the circumference centered on the plug center axis PC. The plug radial direction is the direction perpendicular to the plug center axis PC.

By forming the nozzle hole 51 in this manner, the airflow introduced from the nozzle hole 51 into the auxiliary combustion chamber 50 creates a swirl flow in the auxiliary combustion chamber 50. In this embodiment, the swirl flow is generated in a counterclockwise spiral shape in FIG. 5 around the plug center axis PC.

As shown in Figures 1 to 3, the ground electrode 6 is provided on the housing 2 or the plug cover 5. The center electrode 4 has a lateral protrusion 42 that protrudes outward in the plug radial direction. The protruding end of the lateral protrusion 42 faces the ground electrode 6 in the plug radial direction across a discharge gap G.

In this embodiment, a rectangular parallelepiped electrode member 420 is joined to the center electrode 4. One end of the electrode member 420 protrudes toward the ground electrode 6 beyond the outer circumferential end of the center electrode 4. This protruding portion serves as a lateral protrusion 42.
The opposing surfaces of the ground electrode 6 and the lateral protrusion 42 are both formed in a flat shape. The opposing surfaces of the ground electrode 6 and the lateral protrusion 42, i.e., the discharge surfaces, are disposed approximately parallel to each other.

In this embodiment, the ground electrode 6 is joined to a portion between the tip of the housing 2 and the base end of the plug cover 5. The ground electrode 6 can be joined to the tip surface of the housing 2, or to the plug cover 5. The ground electrode 6 protrudes from between the tip of the housing 2 and the base end of the plug cover 5 in the plug radial direction toward the plug center axis PC. The discharge gap G is located on the tip side of the tip of the housing 2.

As shown in Figs. 1 and 2, the point where the nozzle axis 51L of the gap opposed nozzle 510 intersects with the inner surface of the auxiliary combustion chamber 50 at a position different from the gap opposed nozzle 510 is defined as point A1, and the distance from the gap opposed nozzle 510 to point A1 is defined as L1. At this time, the distance L2 from the gap opposed nozzle 510 to the discharge gap G is less than half of the distance L1. That is, the linear distance L2 between points A3 and A2 shown in Figs. 1 and 2 is less than half of the linear distance L1 between points A3 and A1. The distance L2 can be shorter than the inner diameter of the housing 2, for example. The distance L2 can be less than 1/2 the inner diameter of the housing 2, for example.

An internal combustion engine 10 equipped with the above-described spark plug 1 is shown in FIG.
The internal combustion engine 10 has a main combustion chamber 11, a spark plug 1, and an injector 71. The spark plug 1 is arranged so that the outer surface 52 of the plug cover 5 faces the main combustion chamber 11. The injector 71 injects fuel directly into the main combustion chamber 11.

As shown in Figures 4 and 5, the spark plug 1 is arranged so that the injection flow F containing fuel injected from the injector 71 during the compression stroke of the internal combustion engine 10 is directed toward the outer opening 511 of the gap opposed nozzle hole 510. Note that the arrow F shown in Figures 4 and 5 indicates the direction of the injection flow immediately after fuel injection, and does not necessarily coincide with the air flow in the main combustion chamber 11 during the compression stroke or expansion stroke. Also, the state in which the injection flow F is directed toward the outer opening 511 of the gap opposed nozzle hole 510 is a state in which the outer opening 511 of the gap opposed nozzle hole 510 is visible from the direction of the injection flow F near the plug cover 5 shown in Figure 5.

As shown in FIG. 4, the internal combustion engine 10 has an intake valve 72 that opens and closes an intake port 721, and an exhaust valve 73 that opens and closes an exhaust port 731. The spark plug 1 is disposed in a position in the engine head that is surrounded by the intake port 721 and the exhaust port 731.

The intake port 721 and exhaust port 731 are inclined with respect to the direction of movement of the piston 14 so that their opening direction faces the central axis of the main combustion chamber 11. In addition, the base end surface of the main combustion chamber 11 is inclined so that it faces the tip side as it moves away from the spark plug 1.

An injector 71 is provided adjacent to the intake port 721. The injector 71 is attached in such a position that it injects fuel toward the central axis of the main combustion chamber 11. A piston 74 is slidably disposed within a cylinder 70 that constitutes the main combustion chamber 11.

In the internal combustion engine 10, the intake stroke, compression stroke, expansion stroke, and exhaust stroke are repeated in sequence with the reciprocating motion of the piston 74. During the intake stroke, gas (mainly air) is introduced into the main combustion chamber 11 from the intake port 721, and during the exhaust stroke, gas in the main combustion chamber 11 is exhausted from the exhaust port 731. Due to the way the airflow is introduced during the intake stroke, a certain airflow is formed in the main combustion chamber 11, and this airflow remains even during the compression stroke.

During the compression stroke, the atmosphere in the main combustion chamber 11 is compressed, and air flows into the auxiliary combustion chamber 50 through the nozzle hole 51. This creates a swirl flow in the auxiliary combustion chamber 50, and the pressure in the auxiliary combustion chamber 50 also rises. Then, for example, during the compression stroke, the injector 71 injects fuel directly into the main combustion chamber 11.

Then, as shown in FIG. 4, the fuel injected into the main combustion chamber 11 forms an injection flow F together with the air in the main combustion chamber 11 and hits the base end face of the piston 74. In this embodiment, the base end face of the piston 74 has a concave surface. The injection flow F that hits the base end face of the piston 74 changes its trajectory and heads toward the base end side, i.e., the spark plug 1 side. At this time, the injection flow F reaches the vicinity of the outer opening 511 of the gap-facing injection hole 510 in the spark plug 1.

The injected flow F is a mixture with a relatively high fuel ratio. Therefore, the vicinity of the outer opening 511 of the gap-opposed nozzle 510 where the injected flow F reaches becomes a mixture containing a large amount of fuel. This mixture is then drawn into the auxiliary combustion chamber 50, in which a swirl flow A is formed, via the gap-opposed nozzle 510 as shown in FIG. 5. The high-fuel-density mixture drawn from the gap-opposed nozzle 510 is directed toward the discharge gap G.

Then, near the top dead center of the compression stroke, a discharge is generated in the discharge gap G of the spark plug 1. This allows the mixture to be ignited efficiently. Note that the above-mentioned fuel injection timing and the discharge ignition timing of the spark plug 1 can be changed in various ways depending on the situation and purpose, as described below.

Next, the effects of this embodiment will be described.
In the spark plug 1 for an internal combustion engine, the central axis of the injection hole 51 is inclined with respect to the plug radial direction when viewed from the plug axial direction Z. This makes it possible to form a swirl flow in the auxiliary combustion chamber 50 by the airflow introduced into the auxiliary combustion chamber 50 through the injection hole 51 or the airflow flowing out of the auxiliary combustion chamber 50 through the injection hole 51.

At least one of the injection holes 51 is the above-mentioned gap-facing injection hole 510. When a fuel-containing mixture is introduced into the auxiliary combustion chamber 50 from the gap-facing injection hole 510, the mixture flows toward the discharge gap G, which makes it easy to extend the discharge. Also, a mixture with high fuel density is likely to reach the discharge gap G. This improves the ignition performance in the auxiliary combustion chamber 50, and ultimately improves the ignition performance of the main combustion chamber 11.
The initial flame formed in the discharge gap G is carried to the base end side of the auxiliary combustion chamber 50 by the swirl flow, and as the combustion grows from the base end side or the center of the auxiliary combustion chamber 50, the pressure inside the auxiliary combustion chamber 50 increases when the flame reaches the nozzle hole 51, thereby strengthening the flame jet to the main combustion chamber 11.

For example, when an internal combustion engine is operating at high load, retarded injection and retarded ignition may be performed to suppress pre-ignition. Retarded injection and retarded ignition involve fuel injection and ignition at a timing later than the timing of general fuel injection and ignition. In other words, the fuel injection timing from the injector 71 is set to, for example, the timing just before the piston 74 reaches top dead center during the compression stroke. Specifically, fuel is injected, for example, at a timing of 30° BTDC. BTDC stands for Before Top Dead Center, and indicates how many crank angles before the compression top dead center the timing is. The ignition of the spark plug 1 is set to be substantially at the compression top dead center.

By injecting fuel and igniting at such timing, it is possible to suppress ignition earlier than the desired timing, i.e., premature ignition, and to suppress pre-ignition. On the other hand, when retarded injection is performed, when fuel is supplied to the main combustion chamber 11, a certain amount of air has already filled the auxiliary combustion chamber 50, and the air flow in the main combustion chamber 11 is also weakened. This results in a situation where the amount of fuel introduced into the auxiliary combustion chamber 50 from the injection hole 51 is relatively small.

However, the spark plug 1 of this embodiment has the gap-opposed injection hole 510 described above. Therefore, when a mixture containing fuel is introduced into the auxiliary combustion chamber 50 from the gap-opposed injection hole 510, the mixture with a high fuel density is likely to reach the discharge gap G. Therefore, even if the overall amount of fuel introduced into the auxiliary combustion chamber 50 is reduced, the proportion of fuel supplied to the discharge gap G can be increased. As a result, as described above, the ignition ability in the auxiliary combustion chamber 50 is improved, and ultimately the ignition ability of the main combustion chamber 11 can be improved.

In addition, in the internal combustion engine 10, the spark plug 1 is positioned so that the injection flow F is directed toward the outer opening 511 of the gap-opposed nozzle 510. This makes it easier for a high-fuel-density mixture to be introduced from the gap-opposed nozzle 510 into the auxiliary combustion chamber 50. As a result, the high-fuel-density mixture can more easily reach the discharge gap G, improving ignition performance.

In addition, for example, when the internal combustion engine performs a catalyst warm-up operation, the spark plug 1 may be ignited during the expansion stroke. During the expansion stroke, an airflow is generated from the auxiliary combustion chamber 50 to the main combustion chamber 11 through the nozzle hole 51. In this case, in the spark plug 1 of this embodiment, the discharge or initial flame generated in the discharge gap G is easily carried by this airflow toward the gap-opposed nozzle hole 510. Therefore, ignition is easily achieved near the gap-opposed nozzle hole 510, and cold loss can also be suppressed. As a result, the flame jet to the main combustion chamber 11 can be strengthened. Furthermore, the discharge or discharge plasma, or the initial flame generated in the discharge gap G is easily ejected from the adjacent gap-opposed nozzle hole 510 into the main combustion chamber 11. From this perspective as well, ignition performance can be improved.

The center electrode 4 also has a lateral protrusion 42. The protruding end of the lateral protrusion 42 faces the ground electrode 6 in the plug radial direction via a discharge gap G. Therefore, the discharge gap G exists at a position sufficiently offset from the plug central axis PC. This makes it easier for a strong swirl flow to pass through the discharge gap G. This makes it easier for the discharge to be extended, further improving ignition performance.

In addition, as shown in Figures 1 and 2, the distance L2 from the gap opposed injection hole 510 to the discharge gap G is less than half the distance L1 from the gap opposed injection hole 510 to point A1. This allows the gap opposed injection hole 510 and the discharge gap G to be closer together. As a result, ignition performance can be further improved in both the compression stroke and the expansion stroke.

The discharge gap G is also positioned closer to the tip of the housing 2 than the tip. This also allows the gap-facing injection hole 510 and the discharge gap G to be closer together. As a result, ignition performance can be further improved during both the compression stroke and the expansion stroke.

Even when the fuel injection timing is the intake stroke, the same effect as described above can be achieved with this embodiment in that the discharge in the discharge gap G can be easily extended. That is, for example, when EGR combustion (i.e., exhaust gas recirculation combustion) is used, fuel is injected during the intake stroke and ignited during the compression stroke. In this case, too, the spark plug 1 of this embodiment can easily extend the discharge, improving ignition performance.

As described above, this embodiment can provide a spark plug for an internal combustion engine with excellent ignition properties, and an internal combustion engine.

(Embodiment 2)
In this embodiment, as shown in FIG. 6, the ground electrode 6 is provided upright on the base end side of the plug cover 5.
That is, one end of the ground electrode 6 is joined to a part of the plug cover 5 on the tip side of the auxiliary combustion chamber 50. The side surface of the other end of the ground electrode 6 faces the tip protrusion 41 of the center electrode 4 in the plug radial direction. This forms a discharge gap G between the side surface of the ground electrode 6 and the side surface of the tip protrusion 41. The nozzle axis 51L of the gap opposing nozzle 510 passes through this discharge gap G.

The rest is the same as in the first embodiment.
This embodiment also has the same effects as the first embodiment.
In addition, among the symbols used in the second and subsequent embodiments, the same symbols as those used in the previous embodiments represent the same components, etc. as those in the previous embodiments, unless otherwise specified.

(Embodiment 3)
In this embodiment, as shown in FIG. 7, a part of the housing 2 serves as a ground electrode 6 .
In other words, no electrode member for forming the ground electrode 6 is particularly joined to either the housing 2 or the plug cover 5. The lateral protrusion 42 of the center electrode 4 faces a part of the housing 2. A discharge gap G is formed between this lateral protrusion 42 and a part of the housing 2. As a result, the part of the housing 2 facing the lateral protrusion 42 across the discharge gap G becomes the ground electrode 6.

The gap-facing nozzle hole 510 is formed so that its nozzle hole axis 51 L passes through the discharge gap G between the lateral protrusion 42 and a part of the housing 2 .
The rest is the same as in the first embodiment. This embodiment also has the same effects as the first embodiment.
It should be noted that a part of the plug cover 5 may be used as the ground electrode 6 in a configuration substantially similar to that described above.

(Embodiment 4)
In this embodiment, as shown in FIG. 8, the center electrode 4 does not have a lateral protrusion 42 .
In this embodiment, one end of the ground electrode 6 joined to the housing 2 or the plug cover 5 faces a side surface of the center electrode 4. A discharge gap G is formed between the side surface of the center electrode 4 and the one end of the ground electrode 6. The nozzle hole axis 51L of the gap opposing nozzle hole 510 passes through this discharge gap G.
The rest is the same as in the first embodiment. This embodiment also has the same effects as the first embodiment.

(Embodiment 5)
In this embodiment, as shown in FIG. 9, a center electrode 4 and a ground electrode 6 are opposed to each other in the axial direction Z to form a discharge gap G.
In this embodiment, the ground electrode 6 is disposed opposite the tip end of the center electrode 4 having the lateral protrusion 42. This provides a discharge gap G at the tip end of the center electrode 4. The discharge gap G is formed at a position offset from the plug central axis PC. The nozzle hole axis 51L of the gap opposing nozzle hole 510 passes through this discharge gap G.
The rest is the same as in the first embodiment. This embodiment also has the same effects as the first embodiment.

In each of the above-described embodiments, for example, a precious metal tip may be joined to at least one of the center electrode 4 and the ground electrode 6. The plug cover 5 and the housing 2 may also be configured as an integrated part. In addition, the above-described embodiments may be appropriately combined.

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

1...spark plug, 2...housing, 3...insulator, 4...center electrode, 5...plug cover, 50...auxiliary combustion chamber, 51...nozzle, 51L...extension of central axis of gap-opposed nozzle, 510...gap-opposed nozzle, 6...ground electrode, G...discharge gap, Z...plug axial direction

Claims (4)

A cylindrical insulator (3);
a center electrode (4) held on the inner circumferential side of the insulator and protruding from the insulator toward the tip side;
a cylindrical housing (2) that holds the insulator on its inner periphery;
a ground electrode (6) forming a discharge gap (G) between itself and the center electrode;
a plug cover (5) provided at the tip of the housing so as to cover a sub-combustion chamber (50) in which the discharge gap is disposed,
The plug cover is formed with a nozzle hole (51) that communicates the auxiliary combustion chamber with the outside,
When viewed from the plug axial direction, the central axis of the injection hole is inclined with respect to the plug radial direction,
At least one of the nozzle holes is a gap-facing nozzle hole (510) in which an extension line (51L) of a central axis of the nozzle hole passes through the discharge gap,
a point where an extension of a central axis of the gap opposed injection hole intersects with an inner surface of the pre-combustion chamber at a position different from that of the gap opposed injection hole is defined as point A1, and a distance from the gap opposed injection hole to the point A1 is defined as L1, wherein a distance (L2) from the gap opposed injection hole to the discharge gap is less than half of distance L1 . The spark plug for an internal combustion engine according to claim 1, wherein the ground electrode is provided on the housing or the plug cover, the center electrode has a lateral protrusion (42) that protrudes outward in the plug radial direction, and the protruding end of the lateral protrusion faces the ground electrode in the plug radial direction via the discharge gap. 3. The spark plug for an internal combustion engine according to claim 1, wherein the discharge gap is formed on a tip side of the tip of the housing. An internal combustion engine (10) comprising the spark plug for an internal combustion engine according to any one of claims 1 to 3 ,
A main combustion chamber (11);
The spark plug is disposed so that an outer surface (52) of the plug cover faces the main combustion chamber;
an injector (71) for injecting fuel directly into the main combustion chamber;
The spark plug is arranged so that an injection flow (F) containing the fuel injected from the injector during a compression stroke of the internal combustion engine is directed toward an outer opening (511) of the gap opposing nozzle hole.

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