JP7143935B2 - pre-chamber internal combustion engine - Google Patents

Description

The present disclosure relates to pre-chamber internal combustion engines.

BACKGROUND ART Conventionally, a pre-chamber type internal combustion engine having a main chamber and a pre-chamber provided adjacent to the main chamber has been proposed (see, for example, Japanese Patent No. 4561522). In such a pre-chamber internal combustion engine, an air-fuel mixture is formed from fuel injected into the main chamber. The formed air-fuel mixture is supplied into the pre-chamber through the communication passage and ignited by the ignition plug in the pre-chamber. This creates a flame. The flame formed in the auxiliary chamber is jetted into the main chamber through the communication passage and ignites the air-fuel mixture in the main chamber. In this way, the flame formed in the pre-chamber is injected into the main chamber, thereby increasing the combustion speed of the main chamber. This allows operation at leaner air-fuel ratios and improves fuel efficiency.

In the pre-chamber type internal combustion engine described in Japanese Patent No. 4561522, when the piston is near the top dead center of compression, the center axis of the first injection port is within the cylinder without colliding with the piston crown surface. Aim at the wall. Further, the central axis of the second injection port is oriented toward the bottom outer peripheral portion of the cavity of the crown surface of the piston when the piston is in the vicinity of the compression top dead center.

However, in the pre-chamber internal combustion engine disclosed in Japanese Patent No. 4561522, the injection port faces the inner wall surface of the cylinder. Therefore, the flame collides with the inner wall surface of the cylinder, and the heat of the flame is taken away by the inner wall surface of the cylinder. As a result, cooling loss occurs and the combustion rate in the main chamber slows down.

An embodiment of the present disclosure relates to a pre-chamber internal combustion engine in which a flame injected from a pre-chamber toward a main chamber is suppressed from colliding with a cylinder, thereby reducing cooling loss.

According to an embodiment of the present disclosure, a pre-chamber internal combustion engine includes a main chamber, a pre-chamber, and a communication passage. A main chamber is defined by the cylinder head, the cylinder, and the piston. The auxiliary chamber protrudes from the cylinder head toward the main chamber and is separated from the main chamber. The communication passage communicates the main chamber and the sub chamber, and has an injection port for injecting the flame generated in the sub chamber into the main chamber. The injection port is configured to guide the flame in the direction opposite to the direction of rotation of the swirling flow generated in the main chamber.

Generally, it is widely known that intake air introduced into a combustion chamber generates a swirling flow called swirl. Various techniques are also widely known for promoting the generation of a swirling flow in order to improve combustion efficiency. In the internal combustion engine according to the embodiment of the present disclosure, the injection port of the communication passage is configured to guide the flame in the direction opposite to the direction of rotation of this swirling flow. As a result, the injection direction of the flame injected into the main chamber from the injection port is opposite to the rotation direction of the swirl flow. As a result, the flame injected into the main chamber from the injection port is disturbed and diffused by the swirling flow. As a result, the collision of the flame with the cylinder is suppressed, and the loss of heat from the flame is reduced. Therefore, the occurrence of cooling loss is reduced.

The injection port may extend in a direction opposite to the direction of rotation of the swirling flow toward the main chamber.

According to this configuration, the flame injected into the main chamber from the injection port is easily diffused by the swirling flow.

The inner diameter of the injection port may increase as it approaches the main chamber.

The larger the area of the injection port of the communication passage for injecting the flame into the main chamber, the wider the injected flame and the larger the diameter of the flame. If the injection port area is small, the flame is throttled and the amount of flame injection is reduced. According to this configuration, the inner diameter of the injection port increases as it approaches the main chamber, thereby increasing the area of the injection port. This prevents the diameter of the flame injected from the communication passage from increasing and the amount of flame passing through the communication passage from decreasing.

The communication path may have an inner wall surface formed along a tangential line to the inner wall of the pre-chamber when viewed in the rotation axis direction of the swirling flow.

According to this configuration, the air-fuel mixture introduced from the communication passage into the pre-chamber is led to the inner circumference of the wall. As a result, the air-fuel mixture tends to form a vortex in the pre-chamber. For this reason, unevenness in the air-fuel mixture in the pre-chamber and variation in the flow of the air-fuel mixture can be prevented. As a result, the air-fuel mixture in the pre-chamber is easily ignited.

The diameter of the inner circumference of the wall may increase from the main chamber towards the cylinder head.

According to this configuration, the flow velocity of the air-fuel mixture introduced into the pre-chamber from the communication passage weakens toward the cylinder head. That is, the velocity of the air-fuel mixture vortex weakens. This prevents misfiring due to too high flow velocity of the mixture.

1 is a longitudinal sectional view showing a schematic configuration of a pre-chamber internal combustion engine according to an embodiment of the present disclosure; FIG. FIG. 2 is a cross-sectional view showing a communication passage forming portion of the pre-chamber internal combustion engine of FIG. 1 ; FIG. 2 is a vertical cross-sectional view showing a communication passage formation portion of the pre-chamber internal combustion engine of FIG. 1 ; FIG. 2 is a schematic diagram for explaining the state of an air-fuel mixture during an intake stroke and a compression stroke of the auxiliary chamber type internal combustion engine of FIG. 1; FIG. 2 is a schematic diagram for explaining a state of a flame of an air-fuel mixture after ignition of the pre-chamber internal combustion engine of FIG. 1; FIG. 4 is a vertical cross-sectional view showing a schematic configuration of a pre-chamber according to another embodiment of the present disclosure;

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following specification, the cylinder axial direction Q indicates the direction in which the piston slides along the cylinder. When describing the vertical direction, the cylinder axial direction Q is indicated, and the cylinder head side is defined as "upper" and the piston side is defined as "lower". The left-right direction L is perpendicular to the cylinder axial direction Q and indicates the direction in which the intake port and the exhaust port are arranged. The crankshaft direction P is perpendicular to the cylinder shaft direction Q and indicates the direction in which the cylinders are arranged.

As shown in FIG. 1, a pre-chamber internal combustion engine 1 includes a main chamber 4, a pre-chamber 6, a plurality of communication passages 8 communicating between the main chamber 4 and the pre-chamber 6, and an ignition device provided in the pre-chamber 6. A plug 10 , a fuel injection valve 12 , and a swirling flow generator 14 are provided. In this embodiment, the sub-chamber internal combustion engine 1 is an in-line internal combustion engine in which a plurality of cylinders N including the main chamber 4 and the sub chamber 6 are arranged in series. That is, each cylinder N is provided with a main chamber 4 , a sub chamber 6 , a plurality of communication passages 8 , a spark plug 10 , and a fuel injection valve 12 . However, the arrangement of the cylinders N is not limited to this, and may be V-shaped or horizontally opposed.

The main chamber 4 is a space defined by the cylinders 101 a of the cylinder block 101 , the cylinder head 102 and the pistons 103 . In this embodiment, the main chamber 4 has a pent roof shape and has two slopes toward the intake port 105 side and the exhaust port 110 side of the cylinder head 102 . The main chamber 4 is connected to an intake port 105 via two intake valves 104a and 104b driven by intake cams (not shown). The intake port 105 is connected to an intake passage (not shown), a throttle valve, and an air cleaner. The main chamber 4 is connected to an exhaust port 110, an exhaust passage (not shown), and an exhaust purification catalyst (not shown) through two exhaust valves 109a and 109b driven by an exhaust cam (not shown). not shown). The auxiliary chamber type internal combustion engine 1 outputs power through a crankshaft (not shown) provided in the direction in which the cylinders N are arranged. Piston 103 drives the crankshaft via a connecting rod (not shown).

The auxiliary chamber 6 is provided at the top of the pent roof shape and adjoins the main chamber 4 . The sub-chamber 6 is a space defined by a sub-chamber wall 61 . The sub-chamber 6 protrudes from the cylinder head 102 toward the main chamber 4 and is separated from the main chamber 4 via a sub-chamber wall 61 . In this embodiment, the auxiliary chamber 6 is provided substantially at the center of the line of intersection (ridge line) of the two slopes of the pent roof shape of the main chamber 4 . However, the auxiliary chamber 6 may be provided offset from the approximate center of the main chamber 4 . In this embodiment, the subchamber 6 has the same center X1 as the main chamber 4 . The volume of the pre-chamber 6 is smaller than that of the main chamber 4 , and the flame of the air-fuel mixture ignited by the spark plug 10 quickly propagates into the pre-chamber 6 .

FIG. 2 is a cross-sectional view of the auxiliary chamber 6 at the portion where the communicating passage 8 is formed, as viewed from the piston 103 side. As shown in the enlarged view of FIG. 1 and FIG. 2, the auxiliary chamber wall 61 has a circular cross section centered on the center X1, and the bottom portion 61a is hemispherical. FIG. 3 is a vertical cross-sectional view of the formation portion of the communication path 8 perpendicular to the left-right direction L. As shown in FIG. As shown in FIG. 3, the diameter Dr of the inner circumference 61c of the auxiliary chamber wall 61 increases from the main chamber 4 side toward the cylinder head 102 side. That is, the diameter Dr of the inner circumference 61c of the auxiliary chamber wall 61 increases from the bottom to the top when viewed in the vertical direction (same as the cylinder axial direction Q).

As shown in FIGS. 2 and 3 , a plurality of communication passages 8 are provided in the bottom portion 61 a of the auxiliary chamber wall 61 . The communication passage 8 communicates the main chamber 4 and the sub chamber 6 and guides the air-fuel mixture in the main chamber 4 to the sub chamber 6 . The air-fuel mixture introduced into the pre-chamber 6 is ignited in the pre-chamber 6 and pre-combusted. As shown in FIG. 2 , the communication passage 8 has an injection port 8 a on the surface of the outer circumference 61 b of the pre-combustion chamber wall 61 for injecting the flame preliminarily burned in the pre-combustion chamber 6 . The injection port 8 a is formed along the surface of the outer circumference 61 b of the sub chamber wall 61 . The communication passage 8 also has an inlet 8 b for introducing the air-fuel mixture into the pre-chamber 6 on the surface of the inner circumference 61 c of the pre-chamber wall 61 . The introduction port 8 b is formed along the surface of the inner circumference 61 c of the auxiliary chamber wall 61 . In this embodiment, for example, four communication paths 8 are provided.

The jet port 8a of the communication passage 8 guides the flame jetted from the jet port 8a along the outer circumference 61b of the auxiliary chamber wall 61 in a direction U opposite to the rotational direction F of the swirl flow SW generated in the main chamber 4. , and in this embodiment, the injection port 8 a extends in the opposite direction U toward the main chamber 4 . Here, the flame injected from the injection port 8a is injected along the center line C1 of the injection port 8a. Further, the swirling flow SW flows along the tangent line S1 at the intersection O1 between the center line C1 and the outer circumference 61b. That the communication path 8 extends along the direction U opposite to the rotation direction F of the swirling flow SW means that the center line C1 (including an extension of the center line C1) extends in the direction U opposite to the perpendicular R1 at the intersection O1. Say to incline. That is, an obtuse angle A is formed by the tangent line S1 and the center line C1. At least the injection port 8a should extend in the opposite direction U, and the communication passage 8 may extend, for example, in the radial direction of the pre-chamber 6 except for the injection port 8a.

The communication passage 8 has an inner wall surface 8c located outside the pre-chamber 6 (the inner wall surface on the far side from the center X1 when viewed in the crankshaft direction P or the left-right direction L) and an inner wall surface located inside the pre-chamber 6. 8d (the inner wall surface on the side closer to the center X1 when viewed in the crankshaft direction P or the left-right direction L). The inner wall surface 8c and the inner wall surface 8d of the communicating passage 8 face each other in a direction U opposite to the rotational direction F of the swirling flow SW. The inner wall surface 8d located on the upstream side in the opposite direction U and located inside the sub chamber 6 is located on the downstream side in the opposite direction U. As shown in FIG. The inner wall surface 8c positioned outside the sub-chamber 6 is formed along the tangent line S2 of the inner circumference 61c of the sub-chamber wall 61. As shown in FIG. Preferably, the inner wall surface 8c of the communication passage 8 is formed along the tangent line S2 from the introduction port 8b to the injection port 8a. As a result, there is no level difference between the injection port 8a and the introduction port 8b and between the introduction port 8b and the surface of the inner circumference 61c of the auxiliary chamber 6. FIG. Therefore, when the air-fuel mixture is introduced into the pre-chamber 6 during the compression stroke, the pressure loss caused by the step is suppressed. As a result, a spiral lateral vortex is smoothly formed in the pre-chamber 6 along a plane perpendicular to the projecting direction of the pre-chamber 6 . Further, the communicating passage 8 may be formed so as to be inclined in the vertical direction from the main chamber 4 as shown in FIG. 3 and be inclined in the radial direction as shown in FIG. As a result, the horizontal vortex rises inside the pre-chamber 6 .

Further, as shown in FIG. 2, the inner diameter of the injection port 8a of the communication passage 8 increases as the main chamber 4 is approached. More specifically, the inner diameter Da at the injection port 8a of the space formed by the outer inner wall surface 8c and the inner inner wall surface 8d of the communicating passage 8 is larger than the inner diameter Db at the introduction port 8b of the space, The inner diameter of the communication passage 8 gradually expands from the introduction port 8b to the injection port 8a. Therefore, the area along the outer periphery 61b of the injection port 8a becomes larger than the area along the inner periphery 61c of the introduction port 8b. As a result, the injection amount of flame passing through the communication passage 8 is prevented from decreasing. Furthermore, the inner diameter of the injection port 8a expands in the opposite direction U to the rotation direction F of the swirling flow SW. That is, the inner wall surface 8d is inclined in the opposite direction U (the direction in which the inner diameter of the injection port 8a expands) relative to the inner wall surface 8c. As a result, the flame injected from the injection port 8a is oriented in the direction U opposite to the rotational direction F of the swirling flow SW. As a result, the flame injected from the injection port 8a is more likely to be disturbed and diffused by the swirling flow SW. Note that at least the inner diameter of the injection port 8a should be enlarged in the opposite direction U, and the inner diameter of the communication passage 8 excluding the injection port 8a may be constant, for example. Moreover, it is sufficient that the inner wall surface 8d of at least the injection port 8a extends in the opposite direction U than the inner wall surface 8c.

As shown in FIGS. 1 and 2, the center electrode 10a of the spark plug 10 is arranged at a position overlapping the center X1 of the pre-chamber 6. As shown in FIG. As shown in FIG. 3, the center line C1 of the communication passage 8 intersects the wall surface of the inner periphery 61c of the pre-chamber wall 61 of the pre-chamber 6 at a position H. As shown in FIG. A tip portion 10c of the center electrode 10a of the spark plug 10 is arranged at a position higher than the position H.

A fuel injection valve 12 is provided toward the main chamber 4 . Also, the fuel injection valve 12 is provided outside the auxiliary chamber 6 . In this embodiment, the fuel injection valve 12 injects fuel directly into the main chamber 4 . That is, the auxiliary chamber internal combustion engine 1 is a direct injection internal combustion engine. The injection amount and injection timing of the fuel injection valve 12 are controlled. The fuel injection valve 12 is also connected to a fuel injection pump (not shown) and a fuel tank. The fuel injection valve 12 is arranged on the intake valve 104 side of the cylinder head 102 . In this embodiment, the air-fuel ratio of the auxiliary chamber type internal combustion engine 1 is set to a value leaner than the stoichiometric air-fuel ratio. That is, the pre-chamber internal combustion engine 1 is operated with lean combustion. This improves fuel efficiency.

As shown in FIG. 4 , the swirling flow generator 14 generates swirling flow SW swirling in the rotation direction F in the main chamber 4 . In this embodiment, the swirling flow generator 14 generates the swirling flow SW by changing the lift heights of the intake valves 104a and 104b. However, the swirling flow generating section 14 may generate the swirling flow SW depending on the shape of the intake port 105 . Further, in the present embodiment, the swirl flow SW is a swirl flow that swirls counterclockwise when viewed from the piston 103 side with respect to a plane perpendicular to the sliding direction of the piston 103 (cylinder axial direction Q). The swirl flow SW swirls along the inner wall surface of the cylinder 101 a and along the outer circumference 61 b of the auxiliary chamber wall 61 .

In the pre-chamber internal combustion engine 1 configured as described above, the intake valves 104a and 104b are opened in the intake stroke, and the piston 103 is lowered to introduce the intake air into the main chamber 4 and the pre-chamber 6. . At this time, a swirling flow SW is generated in the main chamber 4 due to the difference in lift height between the intake valves 104a and 104b. Further, in this embodiment, the intake air is pressurized by a supercharger (not shown). As a result, the pressures in the main chamber 4 and the sub chamber 6 become the same as the intake pressure. In the intake stroke, the fuel injection valve 12 mainly injects fuel to supply fuel to the main chamber 4 . The injected fuel mixes with intake air in the main chamber 4 to form an air-fuel mixture. The air-fuel mixture is supplied to the entire main chamber 4 as the piston 103 descends.

In the compression stroke, the intake valves 104a and 104b are closed, the piston 103 is raised, and the air-fuel mixture in the main chamber 4 is compressed. As shown in FIG. 4 , when the piston 103 rises in the compression stroke, the air-fuel mixture is introduced from the main chamber 4 through the communication passage 8 into the auxiliary chamber 6 . At this time, the air-fuel mixture introduced into the pre-chamber 6 becomes an ascending lateral vortex (see the arrow inside the pre-chamber 6 in FIG. 4) by the communication passage 8 .

In this embodiment, the inner wall surface 8c of the communicating passage 8 is formed along the tangent line S2 of the inner circumference 61c of the sub chamber wall 61. As shown in FIG. As a result, a rising horizontal vortex is generated along the inner circumference 61c in the pre-chamber 6, and the spark plug 10 ignites this horizontal vortex. On the other hand, the diameter Dr of the inner circumference 61c of the auxiliary chamber wall 61 expands from the main chamber 4 toward the cylinder head 102 (see FIG. 3). As a result, the flow velocity of the transverse vortex in the pre-chamber 6 is reduced. As a result, misfiring caused by the flow velocity of the transverse vortex in the pre-chamber 6 being too high is prevented.

The air-fuel mixture introduced into the pre-chamber 6 is ignited by the ignition plug 10 and burned. As shown in FIG. 5, at this time, the flame G is injected from the injection port 8a. Then, the air-fuel mixture in the main chamber 4 is combusted, and the combustion gas generated by the combustion increases the pressure. This causes the piston 103 to be pushed down and proceed to the expansion stroke.

In this embodiment, the injection port 8a of the communication passage 8 extends in the opposite direction U to the rotation direction F of the swirl flow SW generated in the main chamber 4 along the outer circumference 61b of the sub chamber wall 61. lead the flame G to . As a result, the flame G is opposed to the swirl flow SW after being injected. Therefore, the flame G is disturbed and diffused like the flame G1 by the swirling flow SW. As a result, the flame G1 diffuses into the space V in the main chamber 4 between the flame G and the flame injected from the adjacent communication passage 8. As shown in FIG. The space V does not reach the flame G, and combustion tends to be unbalanced. The flame G1 reaches the space V by the flame G facing the swirling flow SW, being disturbed and diffused by the swirling flow SW. As a result, the main chamber 4 burns homogeneously. In addition, the flame G is weakened in penetration force by the swirling flow SW, and the flame G is prevented from directly striking the cylinder 101a. This reduces the cooling loss that occurs when the flame G is cooled by the cylinder 101a.

Furthermore, in the present embodiment, the inner diameter of the communicating passage 8 increases from the inner diameter Db of the communicating passage 8 at the inlet 8b to the inner diameter Da of the communicating passage 8 at the injection port 8a. As the inner diameter Da of the injection port 8a increases, the area of the injection port 8a increases. This also increases the diameter of the flame injected from the injection port 8a. Therefore, a large flame G1 is ejected into the space V in the main chamber 4 between the flame G ejected from the communicating passage 8 and the flame G ejected from the adjacent communicating passage 8. As shown in FIG. As a result, combustion in space V is promoted. In addition, the diameter of the injection port 8a increases in the opposite direction U to the rotation direction F of the swirling flow SW. As a result, more flame G faces the swirling flow SW. That is, the number of flames facing the swirling flow SW increases. Therefore, the space V is supplied with more flames G1. As a result, combustion in space V is promoted.

In the exhaust stroke, the exhaust valve 109 opens, the piston 103 rises from the bottom dead center, and combustion gas (exhaust gas) in the cylinder is discharged to the exhaust port 110 . Then, when the piston 103 reaches the top dead center, the intake stroke begins again. Thus, when the piston 103 reciprocates twice, four strokes are completed.

As described above, in the auxiliary chamber type internal combustion engine 1 of the present embodiment, the injection port 8a of the communication passage 8 is positioned along the outer circumference 61b of the auxiliary chamber wall 61 in the rotational direction F of the swirl flow SW generated in the main chamber 4. directs the flame G in the opposite direction U of . As a result, cooling loss of the flame G injected from the auxiliary chamber 6 toward the main chamber 4 is prevented, and combustion in the main chamber 4 is promoted.

<Other embodiments>
Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from the gist of the invention. In particular, multiple modifications described herein can be arbitrarily combined as required.

In the above embodiment, the auxiliary chamber type internal combustion engine 1 is a direct injection internal combustion engine, but the present disclosure is not limited to this. For example, it may be a sub-chamber internal combustion engine having an intake port injector provided in the intake port 105 .

In the above embodiment, four communicating paths 8 are provided in the auxiliary chamber wall 61, but the present disclosure is not limited to this. One or a plurality of communication paths 8 may be provided.

In the above embodiment, the inner diameter of the communication passage 8 expands toward the outer circumference 61b of the sub chamber wall 61, but the present disclosure is not limited to this. For example, the inner diameter of the communication passage 8 may be constant. That is, the inner diameter Da at the injection port 8a in FIG. 2 and the inner diameter Db at the introduction port 8b may be the same.

In the above embodiment, the communication path 8 is provided at one position in the direction in which the auxiliary chamber 6 protrudes, but the present disclosure is not limited to this. As shown in FIG. 6, the first communication path 208 and the second communication path 209 may be provided at different positions in which the auxiliary chamber 6 protrudes. In this case, the inner diameter of either one of the first communication path 208 and the second communication path 209 may be constant. Also, the inner diameter of the other communicating passage may be expanded toward the outer circumference 261 b of the sub chamber wall 261 . For example, when the first communication path 208 is provided at a distance closer to the tip portion 210 c of the spark plug 210 than the second communication path 209 is, the inner diameter of the first communication path 208 extends toward the outer circumference 261 b of the auxiliary chamber wall 261 . can be expanded by On the other hand, the inner diameter of the second communication path 209 may be constant. As a result, the amount of flame injected from the first communication passage 208 near the tip 210c of the spark plug 210 increases.

In the above embodiment, the bottom portion 61a has a hemispherical shape, but the present disclosure is not limited to this. As shown in FIG. 6, the shape of the bottom portion 261a may be a truncated cone shape. Moreover, various shapes such as a conical shape may be used.

In the above embodiment, the swirl flow generator 14 generates a swirl flow, but the present disclosure is not limited to this. The swirl flow generator 14 may generate a vertical vortex swirling in one direction along a plane parallel to the cylinder axial direction Q, that is, may generate a tumble flow. In this case, the communication path 8 may be formed along the direction opposite to the direction of rotation of the tumble flow.

In the above embodiment, the shape of the pre-chamber is exemplified by a circular cross-section (hemispherical, cylindrical, etc.) taken along a plane perpendicular to the axial direction of the cylinder. However, the shape of the sub chamber is not limited to this. The shape may be an ellipse or a regular polygon in cross section. A symmetrical shape is preferable from the viewpoint of flame propagation, but it is not limited to this. Geometric expressions such as “diameter direction”, “radial direction”, and “tangent line” in the present disclosure can be appropriately understood by those skilled in the art even if the cross section is not circular. In other words, those skilled in the art will be able to appropriately apply the features of the present disclosure to achieve the same effects as the present disclosure even in embodiments in which the cross section of the pre-chamber is other than circular.

In the above embodiment, a spark ignition internal combustion engine in which an air-fuel mixture is ignited by a spark plug provided in the pre-chamber is taken as an example. Gasoline is used as the fuel in the internal combustion engine of the present disclosure, but it is of course not limited to this, and other fuels such as alcohol may be used. Also, the features of the present disclosure are not limited to spark ignition internal combustion engines, but are also applicable to compression ignition internal combustion engines such as diesel engines. In other words, it is not essential to provide a spark generating means such as a spark plug in the pre-chamber. A similar effect is expected for an internal combustion engine designed so that combustion (pre-combustion) occurs in the pre-chamber. It is well known that even in a compression ignition internal combustion engine, preliminary combustion can be generated in the pre-chamber by directly injecting fuel from an injector into the pre-chamber or by appropriately setting the compression ratio. Moreover, even in a compression ignition internal combustion engine, the fuel is not particularly limited to light oil, and may be gasoline, alcohol, or the like.

According to an embodiment of the present disclosure, the pre-chamber internal combustion engine (1) is
a main chamber (4) defined by a cylinder head (102), a cylinder (101a) and a piston (103);
a sub-chamber (6) projecting from the cylinder head (102) toward the main chamber (4) and separated from the main chamber (4);
a communication passage (8) for communicating the main chamber (4) and the sub chamber (6);
with
The communication passage (8) has an injection port (8a) for injecting the flame generated in the auxiliary chamber (6) into the main chamber (4),
The injection port (8a) is configured to guide the flame in the opposite direction (U) to the rotational direction (F) of the swirling flow (SW) generated in the main chamber (4).

Said injection port (8a) may extend in said opposite direction (U) towards said main chamber (4).

The inner diameter (Da) of the injection port (8a) may increase as it approaches the main chamber (4).

The communication passage (8) has an inner wall surface ( 8c).

An inner diameter (Dr) of the sub chamber (6) may expand from the main chamber (4) toward the cylinder head (102).

This application is based on Japanese Patent Application No. 2019-061137 filed on March 27, 2019, the contents of which are incorporated herein by reference.

1: Auxiliary chamber type internal combustion engine 4: Main chamber 6: Auxiliary chamber 8: Communication passage 8c: Inner wall surface 14: Swirling flow generating part 61: Auxiliary chamber wall 61b: Outer circumference 61c: Inner circumference 101a: Cylinder 102: Cylinder head 103: Piston Da: inner diameter Db: inner diameter Dr: diameter of inner circumference F: rotation direction of swirl flow U: direction opposite to rotation direction of swirl flow S2: tangential line of inner circumference SW: swirl flow

Claims (5)

a main chamber defined by the cylinder head, the cylinder, and the piston;
a sub chamber projecting from the cylinder head toward the main chamber and separated from the main chamber;
a communication passage that communicates the main chamber and the sub chamber;
a fuel injection valve that injects fuel into the main chamber;
with
The communicating passage has an injection port for injecting the flame generated in the auxiliary chamber into the main chamber,
The pre-chamber internal combustion engine, wherein the injection port is configured to guide the flame in a direction opposite to a rotating direction of a swirling flow generated in the main chamber. the injection port extends in the opposite direction toward the main chamber;
A pre-chamber internal combustion engine according to claim 1. The inner diameter of the injection port expands as it approaches the main chamber,
A pre-chamber internal combustion engine according to claim 1 or 2. The communication passage has an inner wall surface formed along a tangential line to the inner circumference of the pre-chamber when viewed in the rotation axis direction of the swirling flow.
A pre-chamber internal combustion engine according to any one of claims 1 to 3. An inner diameter of the sub chamber expands from the main chamber toward the cylinder head,
A pre-chamber internal combustion engine according to any one of claims 1 to 4.

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