JP7255673B2 - pre-chamber internal combustion engine - Google Patents

Description

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

Conventionally, there has been proposed a pre-combustion engine having a main chamber (main combustion chamber) and a sub-combustion chamber connected to the main chamber via a communication passage (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 during compression and is ignited by the spark 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. By injecting the flame formed in the pre-chamber into the main chamber in this way, the combustion speed in the main chamber increases. This allows operation at leaner air-fuel ratios and improves fuel efficiency.

The pre-chamber internal combustion engine described in Japanese Patent No. 4561522 is a direct-injection pre-chamber internal combustion engine that directly injects fuel into the main chamber. In this pre-chamber internal combustion engine, the fuel injected from the fuel injection valve hits the crown surface of the piston, promoting the atomization of the sprayed fuel. After that, the air-fuel mixture is supplied to the pre-chamber.

A direct-injection internal combustion engine that directly injects fuel into the main chamber has the advantage of improving ignition stability in the pre-chamber by efficiently supplying vaporized fuel to the pre-chamber. However, it is difficult to realize the ignition stability, and it is difficult to stably ignite even when the fuel is rich (rich) or lean (lean) than the ideal air-fuel ratio.

Embodiments of the present disclosure relate to a pre-chamber internal combustion engine with improved ignition stability in the pre-chamber.

According to an embodiment of the present disclosure, a pre-chamber internal combustion engine includes a main chamber, a pre-chamber, a communication passage, and an injection section. A main chamber is defined by the cylinder, the cylinder head, 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. The injection part has a plurality of first injection ports that inject fuel into the main chamber. The communication passage has a second injection port for injecting the flame generated in the auxiliary chamber into the main chamber. The second injection port is positioned between sprays respectively injected from two adjacent first injection ports of the injection part.

In this pre-chamber type internal combustion engine, the second injection port of the communication passage facing the injection portion is positioned between the sprays injected from the two adjacent first injection ports arranged with an interval of the injection portion. This makes it difficult for the spray that is injected from the injection part toward the pre-chamber to hit the second injection port of the communication passage directly. Therefore, large fuel droplets contained in the spray are prevented from entering the pre-chamber through the communication passage. Also, the second injection port of this communication passage is located in the region between the sprays. In the area between the sprays, the fuel penetration is weaker than that of the main part of the spray, and large fuel droplets are less likely to be included, and the fuel atomization is advanced. The atomized fuel is supplied to the pre-chamber through the communication passage. Further, the spray injected from the injection part toward the pre-chamber flows along the outer periphery of the partition wall of the pre-chamber. After the injection, the spray flows downstream in the direction opposite to the injection part while drawing in the surrounding fluid, that is, the air in the pre-chamber through the communication passage, due to the Coanda effect. Then, an air-fuel mixture between the sprays having a weaker penetration force than the main part of the spray and in which the fuel atomization has progressed is newly introduced into the pre-chamber through the communication passage. This makes the air-fuel mixture in the pre-chamber homogeneous. Therefore, the efficiency of fuel supply by fuel injection toward the pre-chamber is improved. Also, stable ignition and flame injection in the pre-chamber are realized. As a result, ignition stability in the pre-chamber is improved.

The second injection port of the communication passage may be separated from the central axis of the spray injected from the first injection port of the injection section.

According to this configuration, since the second injection port of the communication passage is spaced from the central axis of the injected spray, the spray with strong penetrating force does not go toward the communication passage. As a result, the supply of atomized fuel into the pre-chamber is promoted, and the homogenization of the air-fuel mixture in the pre-chamber is promoted.

The auxiliary chamber may be separated from the main combustion chamber by being defined by a partition wall, and the partition wall has an inwardly recessed recess at a position through which the spray injected from the first injection port of the injection unit passes. good too.

According to this configuration, since the injected spray does not directly hit the pre-chamber, a better Coanda effect can be expected. As a result, the supply of atomized fuel into the pre-chamber is promoted, and the homogenization of the air-fuel mixture in the pre-chamber is promoted.

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 the relationship between the pre-chamber of the pre-chamber internal combustion engine of FIG. 1 and the spray injected from the fuel injection valve; FIG. 2 is a longitudinal sectional view perpendicular to the direction of the crankshaft, showing the relationship between the pre-chamber of the pre-chamber internal combustion engine of FIG. 1 and the spray injected from the fuel injection valve; FIG. 2 is a longitudinal cross-sectional view perpendicular to the left-right direction, showing the relationship between the pre-chamber of the pre-chamber internal combustion engine of FIG. 1 and the spray injected from the fuel injection valve; FIG. 4 is a transverse cross-sectional view showing the relationship between a pre-chamber of a pre-chamber internal combustion engine of another embodiment of the present disclosure and spray injected from a fuel injection valve; FIG. 4B is a vertical cross-sectional view perpendicular to the crankshaft direction, showing the relationship between the pre-chamber of the pre-chamber internal combustion engine of FIG. 4A and the spray injected from the fuel injection valve; FIG. 10 is a longitudinal cross-sectional view perpendicular to the left-right direction, showing the relationship between the pre-chamber of the pre-chamber internal combustion engine of another embodiment of the present disclosure and the spray injected from the fuel injection valve;

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. The vertical direction refers to the cylinder axial direction Q, with the cylinder head side being "up" and the piston side being "down". The left-right direction R is orthogonal 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 sub-chamber 6 adjacent to the main chamber 4, a plurality of communication passages 8 communicating between the main chamber 4 and the sub-chamber 6, an ignition A plug 10 and a fuel injection valve (an example of an injection portion) 12 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 an intake valve 104 driven by an intake cam (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 also connected to an exhaust port 110, an exhaust passage (not shown), and an air purification catalyst (not shown) via an exhaust valve 109 driven by an exhaust cam (not shown). be. The auxiliary chamber internal combustion engine 1 transmits power to a power transmission device such as a transmission through a crankshaft (not shown). 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 of the main chamber 4 and adjoins the main chamber 4 . The sub-chamber 6 is a space defined by a sub-chamber wall (partition 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 by being defined by 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 . In this embodiment, the subchamber 6 has the same center X1 as the main chamber 4 . However, the auxiliary chamber 6 may be provided offset from the approximate center of the main chamber 4 . The auxiliary chamber wall 61 includes a side wall portion having a circular cross section and a bottom portion 61 a facing the main chamber 4 . The bottom portion 61a is formed, for example, in a hemispherical shape. However, the shape of the bottom portion 61a is not limited to a hemispherical shape. A communicating passage 8 is provided in the bottom portion 61a.

As shown in FIG. 2A, the plurality of communicating passages 8 are radially provided in the bottom portion 61a (see FIG. 2B) of the auxiliary chamber wall 61. As shown in FIG. 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 . Also, the communication passage 8 sends out the flame ignited in the auxiliary chamber 6 to the main chamber 4 . As shown enlarged in FIG. 3, the communication passage 8 has an injection port (second injection port) 8a facing the main chamber 4 and an introduction port 8b facing the auxiliary chamber 6. As shown in FIG. In this embodiment, for example, six communication paths 8 are provided as shown in FIG. 2A.

As shown in FIG. 3, of the communicating passages 8, two communicating passages 8 arranged opposite to the fuel injection valve 12 (the communicating passage 8 arranged on the intake side) have injection openings 8a connected to the fuel injection valves. It is positioned between sprays (spray bodies) S respectively injected from two adjacent injection openings (first injection openings) 12a arranged at intervals in the crankshaft direction P of 12. More specifically, in the present embodiment, of the eight injection ports 12a of the fuel injection valve 12, the spray is injected from two injection ports 12a that are located at the top in the vertical direction and are adjacent to each other in the crankshaft direction P. Between S, the injection port 8a of the communication passage 8 is positioned. As a result, the spray S does not directly hit the injection port 8a, and the fuel injected from the fuel injection valve 12 is less likely to enter directly into the pre-chamber 6 through the communication passage 8. - 特許庁Note that the injection port 8a of at least one communication passage 8 among the plurality of communication passages 8 is positioned between the sprays S respectively injected from two injection ports 12a adjacent to each other in the crankshaft direction P of the fuel injection valve 12. It is good if there is According to this configuration, the atomized fuel with weak fuel penetration force in the region between the sprays S is introduced into the pre-chamber 6 via the communication passage 8 .

Further, as shown in FIGS. 2A and 3, the spray S injected from the fuel injection valve 12 is injected along the spray center axis Cs. The auxiliary chamber wall 61 is located between the spray center axis Cs of the spray S injected from the uppermost injection port 12a in the vertical direction of the fuel injection valve 12 when viewed from the crankshaft direction P. That is, the injection port 8a of the communication passage 8 facing the fuel injection valve 12 is arranged so as to be separated from the spray center axis Cs of the spray S injected from the uppermost injection port 12a of the fuel injection valve 12. . According to this configuration, the distance between the injection port 8a of the communication passage 8 arranged facing the fuel injection valve 12 and the spray S is ensured, so that large fuel droplets are less likely to enter the pre-chamber 6. Further, the injected spray S flows around the outer circumference of the bottom portion 61 a of the auxiliary chamber wall 61 . At this time, the spray S draws in the air-fuel mixture in the pre-chamber 6 from the communication passage 8 arranged in the crankshaft direction P and the communication passage 8 arranged on the exhaust side due to the Coanda effect. As a result, the fuel, which has a weak penetration force and is highly atomized, is easily drawn into the pre-chamber 6 from the communication passage 8 on the intake side. As a result, ignition in the pre-chamber 6 is further stabilized.

As shown in FIGS. 1, 2A and 2B, the spark plug 10 is arranged substantially in the center of the pre-chamber 6. As shown in FIG. A spark plug 10 ignites the air-fuel mixture in the pre-chamber 6 .

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 . The auxiliary chamber 6 injects the flame generated in the auxiliary chamber 6 into the main chamber 4 through the communication passage 8. - 特許庁The flame injected into the main chamber 4 ignites and burns the air-fuel mixture in the main chamber 4 .

As shown in FIGS. 1, 2A and 2B, the fuel injection valve 12 is provided toward the main chamber 4. As shown in FIG. Also, the fuel injection valve 12 is provided outside the auxiliary chamber 6 . In this embodiment, as enlarged in FIG. 3, the fuel injection valve 12 has, for example, eight injection ports 12a. Further, the fuel injection valve 12 injects fuel toward both sides of the auxiliary chamber wall 61 in the crankshaft direction P. As shown in FIG. Two sets of four injection ports 12a are provided, and the two sets of injection ports 12a are provided along a circle having the center of the fuel injection valve 12 as a center. The two sets of injection ports 12a are spaced apart in the crankshaft direction P. As shown in FIG. In this embodiment, the injection port 12 a 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 by a control unit (not shown). The fuel injection valve 12 is also connected to a fuel injection pump (not shown) and a fuel tank. In this embodiment, the fuel injection valve 12 is arranged on the intake valve 104 side of the cylinder head 102 . The fuel injection valve 12 forms an air-fuel mixture in the main chamber 4 by supplying fuel in the form of atomization. Further, the fuel injection valve 12 supplies fuel to the auxiliary chamber 6 via the communication passage 8 by injecting fuel into the main chamber 4 .

As shown in FIG. 2B, the injection port 8a of the communication passage 8 may be separated from the spray center axis Cs of the spray S in the left-right direction R. As shown in FIG. More specifically, the angle between the central axis C of the communication passage 8 and the central axis Cs of the spray S may be set to increase as the distance from the fuel injection valve 12 increases. This configuration makes it more difficult for large fuel droplets to enter the pre-chamber 6 . As a result, ignition in the pre-chamber 6 is further stabilized.

In the pre-chamber internal combustion engine 1 configured as described above, the intake valve 104 is opened and the piston 103 is lowered to allow intake air to flow into the main chamber 4 and the pre-chamber 6 during the intake stroke. In this embodiment, intake air is pressurized by a supercharger (not shown). The pressures in the main chamber 4 and the sub chamber 6 will be the same as the intake pressure. In the intake stroke, the fuel injection valve 12 is controlled so as to perform the first injection for supplying fuel mainly to the main chamber 4 . The fuel injected by the first injection mixes with intake air in the main chamber 4 to form an air-fuel mixture. As the piston 103 descends, the air-fuel mixture is supplied to the entire main chamber 4 . In this embodiment, the target air-fuel ratio 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.

In the compression stroke, the intake valve 104 is closed, the piston 103 is raised, and the air-fuel mixture in the main chamber 4 is compressed. At this time, the pressure in the main chamber 4 rises. Further, the air-fuel mixture flowing into the pre-chamber 6 through the communication passage 8 is throttled by the communication passage 8 and pressure loss occurs. As a result, the pressure in the auxiliary chamber 6 rises with a delay with respect to the pressure in the main chamber 4 . That is, the pressure in the auxiliary chamber 6 becomes lower than the pressure in the main chamber 4 .

When the pressure in the auxiliary chamber 6 becomes lower than the pressure in the main chamber 4, the fuel injection valve 12 is controlled to perform the second injection. The second injection is performed to supply fuel to the pre-chamber 6 via the communication passage 8 .

During the compression stroke, when the piston 103 rises, the air-fuel mixture is introduced from the main chamber 4 into the auxiliary chamber 6 via the communication passage 8 . At this time, the air-fuel mixture is introduced into the auxiliary chamber 6 through the communication passage 8 .

In this embodiment, the pre-chamber 6 and the fuel injection valve 12 have the arrangement relationship described above. That is, when the spray S that is secondly injected from the fuel injection valve 12 toward the pre-chamber 6 does not hit the pre-chamber wall 61 but reaches the side, the spray S is a viscous fluid containing fuel. The later spray S is attracted to the pre-chamber wall 61 by the Coanda effect. Then, the spray S flows along the bottom portion 61a of the auxiliary chamber wall 61 from the direction along the central spray axis Cs. At this time, the spray S draws in the surrounding fluid, that is, the air in the pre-chamber 6 via the communication passage 8 arranged in the crankshaft direction P and the communication passage 8 arranged on the exhaust side, and flows downstream (center). X1 on the opposite side of the fuel injection valve 12). Then, the air-fuel mixture in the region between the sprays S, in which the fuel penetration is weaker than that of the sprays S and in which large fuel droplets are less likely to be included, and in which the fuel atomization has progressed, is newly added to the intake side. It is drawn into the auxiliary chamber 6 via the communicating passage 8 (the communicating passage 8 facing the fuel injection valve 12). As a result, the air-fuel mixture in the pre-chamber 6 becomes homogeneous. Thus, the atomized fuel is supplied to the auxiliary chamber 6 through the communication passage 8 by the second injection. This prevents large droplets of fuel from entering the pre-chamber 6 and destabilizing the ignition in the pre-chamber 6 . Furthermore, in the second injection directed to the pre-chamber 6, the atomized fuel is supplied into the pre-chamber 6, so that the air-fuel mixture in the pre-chamber 6 is stably ignited. As a result, the flame is reliably injected from the injection port 8a, and fuel supply is made more efficient. Also, in the first injection, part of the fuel is introduced into the pre-chamber 6 via the communication passage 8, so that the same effect as in the second injection is obtained.

When the piston 103 rises and compression further progresses, the spark plug 10 ignites the air-fuel mixture in the pre-chamber 6 . With combustion in the sub chamber 6 , flame is injected into the main chamber 4 through the communication passage 8 . 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 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 facing the fuel injection valve 12 is two injection ports 12a adjacent to each other in the crankshaft direction P of the fuel injection valve 12. are positioned between the sprays S respectively injected from . As a result, the spray S injected from the fuel injection valve 12 toward the pre-chamber 6 does not directly hit the injection port 8a of the communication passage 8, so that large fuel droplets contained in the spray S are dispersed through the communication passage 8. entry into the auxiliary chamber 6 is prevented. Further, in the region between the sprays S, the fuel penetration is weaker than that of the sprays S, and large fuel droplets are less likely to be contained therein, and the fuel atomization is progressing. Since the injection port 8 a of the communication passage 8 is located in the region between the sprays S, the atomized fuel is supplied to the auxiliary chamber 6 through the communication passage 8 . Further, the spray S injected from the fuel injection valve 12 toward the pre-chamber 6 flows along the nearby pre-chamber wall 61 due to the Coanda effect after being injected. After the injection, the spray S flows downstream in the direction opposite to the fuel injection valve 12 while drawing in surrounding fluid, that is, air in the pre-chamber 6 via the communication passage 8 . Then, an air-fuel mixture between the sprays S having a weaker penetration force than the sprays S and having advanced fuel atomization is newly introduced into the pre-chamber 6 via the communication passage 8 . As a result, the air-fuel mixture in the pre-chamber 6 becomes homogeneous. As a result, the air-fuel mixture in the pre-chamber 6 is stably ignited.

<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 pre-chamber internal combustion engine that includes an intake port injector provided in the intake port 105 and a direct injection injector provided in the main chamber 4 . The effects of the present disclosure can be obtained if the second injection described above is performed by a direct injector.

As shown in FIGS. 4A, 4B, and 5, in a pre-chamber internal combustion engine 201 of another embodiment, a bottom portion 161a of a pre-chamber 106 is formed into a shape in which a portion of a hemispherical shape is cut into an arc shape. be done. That is, the bottom portion 161a of the auxiliary chamber wall 161 has an arcuate notch portion (recess) 161b. The cutout portion 161b has a shape including a region through which the spray S injected from the fuel injection valve 12 into the main chamber 4 passes when the bottom portion 161a is hemispherical. As shown in FIGS. 4A and 4B, the bottom portion 161a has notches 161b on both sides in the circular crankshaft direction P when viewed in the vertical direction (the piston 103 side in the cylinder axial direction Q). Further, as shown in FIG. 4B, the bottom portion 161a has a notch portion 161b penetrating the semicircular lower portion to the exhaust port 110 side when viewed from the crankshaft direction P. As shown in FIG. As shown in FIG. 5, the bottom portion 161a has notches 161b on both sides of the semicircular center X1 when viewed from the side of the intake port 105 in the left-right direction R. As shown in FIG. Note that the cutout portion 161b may be provided only on the front side when viewed from the side of the intake port 105 in the left-right direction R. That is, the bottom portion 161a (notch portion 161b) should be formed so that the spray S does not directly hit the sub chamber wall 161 .

In addition, when the fuel injection valve 12 injects fuel toward both sides of the auxiliary chamber wall 161 in the crankshaft direction P, the auxiliary chamber 106 and the fuel injection valve 12 are two injection ports adjacent to each other in the crankshaft direction P. The layout relationship is such that the bottom 161a of the sub chamber 6 is positioned between the sprays S ejected from the respective nozzles 12a. If the bottom 161a (notch 161b) of the pre-chamber 106 is provided so that this relationship is established, and the injection direction of each injection port of the fuel injection valve 12 (that is, the spray center axis Cs of the spray S) is set, good.

In another embodiment, the shape of the bottom portion 161a (notch portion 161b) and each injection direction of the fuel injection valve 12 (that is, the spray center axis Cs of the spray S) are adjusted so that the spray S does not directly hit the pre-chamber 6. set, the disclosure is not so limited. Regardless of the shape of the pre-chamber wall 161, the pre-chamber 6 is located between the sprays S injected from the two injection ports 12a adjacent to each other in the crankshaft direction P of the fuel injection valve 12. Each injection direction (that is, the spray central axis Cs of the spray S) may be provided. According to this configuration, the distance between the injection port 8a of the communication passage 8 facing the fuel injection valve 12 and the spray S is ensured, so that large fuel droplets are less likely to enter the pre-chamber 6. Further, the pre-chamber 6 is arranged in a region where the fuel penetration is weak and the fuel is highly atomized. As a result, ignition in the pre-chamber 6 is further stabilized.

Although the plurality of communication paths 8, 108 are arranged radially in this embodiment and other embodiments, the present disclosure is not limited to this. The communication passages 8, 108 may be arranged obliquely with respect to the diametrical direction of the sub chambers 6, 106. By arranging the communication passages 8 and 108 in this manner, a swirling flow is generated in the auxiliary chamber 6 .

In the above embodiment and other embodiments, the fuel injection valve 12 injects fuel toward both sides of the auxiliary chamber walls 61 and 161 in the crankshaft direction P, but the present disclosure is not limited to this. For example, when the fuel injection valve 12 injects fuel toward both sides of the sub chamber walls 61 and 161 in the left-right direction R, between the two injection ports 12a adjacent in the left-right direction R The injection port 8a may be provided so as to be positioned. In other words, two adjacent injection ports 12a may be spaced apart in one direction.

In the above embodiment and other embodiments, 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 and other embodiments, 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, a pre-chamber internal combustion engine (1) comprises a main chamber (4) defined by a cylinder (101a), a cylinder head (102) 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 communicating passage (8) communicating between the main chamber (4) and the sub chamber (6);
an injection part (12) having a plurality of first injection holes (12a) for injecting fuel into the main chamber (4);
with
The communication passage (8) has a second injection port (8a) for injecting the flame generated in the auxiliary chamber (6) into the main chamber (4),
The second injection port (8a) is located between the sprays respectively injected from the two adjacent first injection ports (12a) of the injection part (12).

The second injection port (8a) may be separated from the central axis Cs of the spray injected from the first injection port (12a).

the sub-chamber (106) is separated from the main chamber (4) by being defined by a partition wall (161);
The partition wall (161) may have an inward recess (161b) at a position through which the spray injected from the first injection port (12a) passes.

This application is based on Japanese Patent Application No. 2019-061133 filed on March 27, 2019, the contents of which are incorporated herein by reference.

1 201: Pre-chamber internal combustion engine 4: Main chamber 6 106: Pre-chamber 8 108: Communication passage 8a: Injection port (second injection port)
12: Fuel injection valve (injection part)
12a: injection port (first injection port)
61 161: pre-chamber wall (partition wall)
61a 161a: Bottom 161b: Notch (recess)
101a: Cylinder 102: Cylinder head 103: Piston X1: Center S: Spray

Claims (3)

a main chamber defined by a cylinder, a cylinder head, and a piston;
a sub-chamber protruding from the cylinder head toward the main chamber and separated from the main chamber;
a communicating passage communicating between the main chamber and the sub chamber;
an injection unit provided on the intake side of the main chamber and having a plurality of first injection ports for injecting fuel into the main chamber;
with
said subchamber having the same center as the center of said main chamber;
The communicating passage has a second injection port for injecting the flame generated in the auxiliary chamber into the main chamber,
The second injection ports are arranged in a direction along the crankshaft direction and on an exhaust side opposite to the injection section, and the spray is injected from each of the two adjacent first injection ports of the injection section. A sub-chamber internal combustion engine located between 2. The pre-chamber internal combustion engine according to claim 1, wherein said second injection port is spaced apart from the center axis of the spray injected from said first injection port. The auxiliary chamber is separated from the main chamber by being defined by a partition wall,
3. The partition wall according to claim 1, wherein the partition wall has an inwardly recessed recess at a position through which the spray injected from the first injection port passes , and the second injection port is located in the recess. Pre-chamber internal combustion engine.

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