Auxiliary chamber type internal combustion engine

Abstract

To provide an auxiliary chamber type internal combustion engine that can form an air-fuel mixture around an auxiliary combustion chamber while taking into consideration the flow inside a cylinder.SOLUTION: An auxiliary chamber type internal combustion engine comprises a main combustion chamber, an auxiliary combustion chamber that is disposed separatedly from the main combustion chamber by a partition wall, a fuel injection valve having a first injection and a second injection that is injected in a direction different from the first injection, a first communication passage that is provided in the partition wall and connects the main combustion chamber and the auxiliary combustion chamber, and a second communication passage that connects the main combustion chamber and the auxiliary combustion chamber in a direction different from the first communication passage. The first injection is injected in a direction intersecting with the first communication passage, and the second injection is injected in a direction intersecting with the second communication passage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a pre-chamber internal combustion engine. [Background technology]

[0002] Conventionally, a pre-combustion chamber type internal combustion engine has been known (see, for example, Patent Document 1). The pre-combustion chamber type internal combustion engine of Patent Document 1 has a main combustion chamber and a pre-combustion chamber, an ignition device disposed in the pre-combustion chamber, and a fuel injection valve disposed in the main combustion chamber. The pre-combustion chamber type internal combustion engine of Patent Document 1 is a pre-combustion chamber type internal combustion engine in which an air-fuel mixture is formed in the pre-combustion chamber by supplying fuel injected from the main combustion chamber to the pre-combustion chamber. The air-fuel mixture formed in the pre-combustion chamber is ignited by an ignition device to form a flame. The flame formed in the pre-combustion chamber is injected into the main combustion chamber via a communication passage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 7255673 Summary of the Invention [Problem to be solved by the invention]

[0004] In such a pre-combustion chamber internal combustion engine, it is preferable to form a fuel-rich mixture around the pre-combustion chamber and supply the mixture to the pre-combustion chamber. The pre-combustion chamber internal combustion engine of Patent Document 1 supplies fuel spray from the fuel injection valve to the outside of the pre-combustion chamber, forming a fuel-rich mixture around the pre-combustion chamber. The pre-combustion chamber internal combustion engine of Patent Document 1 takes into account that the fuel spray will be blown away by the flow in the cylinder, and does not disclose how fuel should be injected.

[0005] An object of the present disclosure is to provide an auxiliary combustion chamber type internal combustion engine that can form an air-fuel mixture around the auxiliary combustion chamber while taking into account the flow inside the cylinder. [Means for solving the problem]

[0006] The auxiliary combustion chamber type internal combustion engine according to the present disclosure comprises a main combustion chamber, an auxiliary combustion chamber separated from the main combustion chamber by a partition wall, a fuel injection valve having a first injection and a second injection that is injected in a direction different from that of the first injection, a first communication passage provided in the partition wall that connects the main combustion chamber and the auxiliary combustion chamber, and a second communication passage that connects the main combustion chamber and the auxiliary combustion chamber in a direction different from that of the first communication passage, wherein the first injection is injected in a direction intersecting the first communication passage and the second injection is injected in a direction intersecting the second communication passage. [Effects of the Invention]

[0007] In this auxiliary combustion chamber type internal combustion engine, the first injection is made in a direction intersecting the first communication passage, and the second injection is made in a direction intersecting the second communication passage. As a result, even if in-cylinder flow occurs, at least one of the first injection and the second injection is made toward the first communication passage or the second communication passage. As a result, a fuel-rich mixture is supplied to the auxiliary combustion chamber from the first communication passage or the second communication passage. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an internal combustion engine with a pre-chamber according to an embodiment of the present disclosure; [Figure 2] FIG. 2 is a side view of a pre-combustion chamber wall according to an embodiment of the present disclosure. [Figure 3] FIG. 2 is a bottom view of the vicinity of the auxiliary combustion chamber according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a bottom view illustrating a state of fuel spray according to an embodiment of the present disclosure. [Figure 5] FIG. 10 is a bottom view illustrating a state of fuel spray when an in-cylinder flow occurs according to an embodiment of the present disclosure. [Figure 6] FIG. 2 is a side view illustrating a fuel spray according to an embodiment of the present disclosure. [Figure 7] FIG. 10 is a side view of the auxiliary combustion chamber wall according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the sliding direction of the piston 8 is indicated as P, the side where the intake valve 14 is located is indicated as the intake side IN, and the side where the exhaust valve 16 is located is indicated as the exhaust side EX.

[0010] As shown in Figures 1 and 2, the auxiliary combustion chamber type internal combustion engine 1 includes a main combustion chamber 2, an auxiliary combustion chamber 3, a first communication passage 4, a second communication passage 6, a third communication passage 7, a piston 8, a fuel injection valve 9, and an ignition device 10.

[0011] The main combustion chamber 2 is a space surrounded by the cylinder 11a of the cylinder block 11, the cylinder head 12, and the piston 8. In this embodiment, the main combustion chamber 2 has a pent roof shape, with two slopes formed toward the intake port 12a side and the exhaust port 12b side of the cylinder head 12. The main combustion chamber 2 is connected to the intake port 12a via an intake valve 14. The intake port 12a is connected, for example, to an intake passage (not shown). The main combustion chamber 2 is connected to the exhaust port 12b via an exhaust valve 16. The exhaust port 12b is connected, for example, to an exhaust passage (not shown).

[0012] The auxiliary combustion chamber 3 protrudes from the cylinder head 12 toward the main combustion chamber 2, straddling a ridgeline X (see FIG. 3) formed at the top of the pent roof shape. The auxiliary combustion chamber 3 is disposed separated from the main combustion chamber 2 by an auxiliary combustion chamber wall (an example of a partition wall) 5. The auxiliary combustion chamber 3 is disposed adjacent to the main combustion chamber 2, and has a space surrounded by the auxiliary combustion chamber wall 5.

[0013] 2 and 3, in this embodiment, the auxiliary combustion chamber wall 5 has a side wall 51 and a bottom wall 52. In this embodiment, the side wall 51 is formed in a cylindrical shape, and the bottom wall 52 is formed in a hollow hemispherical shape.

[0014] The bottom wall 52 has a first protrusion 52a (an example of a guide portion) and a second protrusion 52b (an example of a guide portion). The first protrusion 52a is disposed on the exhaust side of the third communication passage 7 and extends closer to the piston 8 than the third communication passage 7 formed in the bottom wall 52. The second protrusion 52b is disposed closer to the cylinder head 12 than the first communication passage 4 (see FIG. 3) and the second communication passage 6 and extends closer to the fuel injection valve 9 (intake side) than the first communication passage 4 (see FIG. 3) and the second communication passage 6.

[0015] In this embodiment, the bottom wall 52 has a thin portion 52c and a thick portion 52d. The thin portion 52c is disposed on the intake side of the bottom wall 52. The thick portion 52d is disposed on the exhaust side of the bottom wall 52. A step surface 52e is formed at the boundary between the thin portion 52c and the thick portion 52d. This step surface 52e connects the first protrusion 52a and the second protrusion 52b, and the first protrusion 52a and the second protrusion 52b are continuous with each other.

[0016] As shown in FIG. 3 , the first communication passage 4 and the second communication passage 6 are arranged in the auxiliary combustion chamber wall 5. The first communication passage 4 connects the main combustion chamber 2 and the auxiliary combustion chamber 3 toward the intake-side cylinder 11a. In this embodiment, the first communication passage 4 and the second communication passage 6 are arranged in the thin-walled portion 52c. The second communication passage 6 is arranged adjacent to the first communication passage 4 and connects the main combustion chamber 2 and the auxiliary combustion chamber 3 in a direction different from that of the first communication passage 4. In this embodiment, the auxiliary combustion chamber internal combustion engine 1 further includes a first intake-side communication passage 4a arranged closer to the ridgeline X than the first communication passage 4, and a second intake-side communication passage 6a arranged closer to the ridgeline X than the second communication passage 6. That is, the auxiliary combustion chamber internal combustion engine 1 of this embodiment has four communication passages on the intake side.

[0017] As shown in FIG. 2, the third communication passage 7 connects the main combustion chamber 2 and the auxiliary combustion chamber 3 toward the piston 8 (see FIG. 1). In this embodiment, the third communication passage 7 is disposed in the thin-walled portion 52c. The third communication passage 7 is disposed so that the center line C3 of the third communication passage 7 overlaps with the center line Cs of the auxiliary combustion chamber 3. As shown in FIG. 1, in this embodiment, the center line Cs of the auxiliary combustion chamber 3 coincides with the center line Cc of the cylinder 11a (the center line of the main combustion chamber 2). Therefore, as shown in FIG. 2, the center line C3 of the third communication passage 7 is formed along the center line Cc of the cylinder 11a toward the bottom dead center side (toward the piston 8) in the sliding direction P.

[0018] As shown in FIG. 3 , in this embodiment, the auxiliary combustion chamber type internal combustion engine 1 further includes a fourth communication passage 17 on the exhaust side of the auxiliary combustion chamber wall 5. The fourth communication passage 17 connects the main combustion chamber 2 and the auxiliary combustion chamber 3 toward the exhaust side. In this embodiment, the fourth communication passage 17 is disposed in the thick-walled portion 52d. Four fourth communication passages 17 are provided, and each of the four fourth communication passages 17 is formed facing a different direction toward the exhaust side. Because the fourth communication passage 17 is formed in the thick-walled portion 52d, the overall length of the passage is longer than that of the first communication passage 4 formed in the thin-walled portion 52c. For this reason, a counterbore portion 18 is provided around the exhaust-side opening of the fourth communication passage 17 (see FIG. 4 or FIG. 6 ). This allows the contact length of the jet flame of the fourth communication passage 17 to be matched with that of the first communication passage 4. As a result, the jet flame ejected from the first communication passage 4 and the jet flame ejected from the fourth communication passage 17 can have the same momentum and spread.

[0019] 1, the piston 8 is housed in a cylinder 11a and slides within the cylinder 11a. The cylinder 11a surrounds the periphery of the main combustion chamber 2. The piston 8 surrounds the main combustion chamber 2 from below.

[0020] The ignition device 10 is disposed in the auxiliary combustion chamber 3. As shown in FIG. 6, the ignition device 10 has an ignition coil (not shown) and an ignition plug 10a. A center electrode 10b and a side electrode 10c of the ignition plug 10a protrude into the auxiliary combustion chamber 3. In this embodiment, the center electrode 10b is disposed on the center line Cs of the auxiliary combustion chamber 3. However, the center electrode 10b may be disposed offset from approximately the center of the auxiliary combustion chamber 3 toward the cylinder 11a.

[0021] The fuel injection valve 9 injects fuel toward the auxiliary combustion chamber 3, forming an air-fuel mixture in the main combustion chamber 2 and the auxiliary combustion chamber 3. In this embodiment, the fuel injection valve 9 is a direct injection type that injects fuel directly into the main combustion chamber 2. In this embodiment, the auxiliary combustion chamber internal combustion engine 1 further includes a port injection valve 19. The port injection valve 19 injects fuel into the intake port 12a, forming an air-fuel mixture in the main combustion chamber 2. However, the auxiliary combustion chamber internal combustion engine 1 may also include, instead of the port injection valve 19, an in-cylinder injection valve that injects fuel into the cylinder, separate from the fuel injection valve 9.

[0022] As shown in FIG. 4 , the fuel injector 9 has a first injection F1 and a second injection F2 that is injected in a direction different from the first injection F1. That is, the fuel injector 9 has at least two injection holes. The first injection F1 is injected in a direction intersecting the first communication passage 4. The second injection F2 is injected in a direction intersecting the second communication passage 6. More specifically, a first spray axis F1x of the first injection F1 and a second spray axis F2x of the second injection F2 intersect with the partition wall between the first communication passage 4 and the second communication passage 6. The first spray axis F1x is an axis positioned at the center of the first injection F1 injected from the fuel injector 9. The second spray axis F2x is an axis positioned at the center of the second injection F2 injected from the fuel injector 9.

[0023] The fuel injection valve 9 faces the auxiliary combustion chamber wall 5 between the first communication passage 4 and the second communication passage 6. More specifically, the central axis C5 of the fuel injection valve 9 is located on the auxiliary combustion chamber wall 5 between the first communication passage 4 and the second communication passage 6. In other words, the first communication passage 4 and the second communication passage 6 are not disposed in positions facing the fuel injection valve 9 when viewed in the direction from the intake side to the exhaust side. By arranging the first communication passage 4 and the second communication passage 6 in this manner, the jet flames injected from the first communication passage 4 and the second communication passage 6 are prevented from directly impinging on the fuel injection valve 9.

[0024] As shown enlarged in FIG. 4, in this embodiment, the first injection F1 is injected so that the angle α between the center line C1 of the first communication passage 4 and the first spray axis F1x of the first injection F1 is within 45 degrees. The second injection F2 is injected so that the angle β between the center line C2 of the second communication passage 6 and the second spray axis F2x of the second injection F2 is within 45 degrees. By injecting the first injection F1 and the second injection F2 in this manner, the fuel injection valve 9 supplies the fuel-rich mixture that collides with and diffuses against the auxiliary-combustion-chamber wall 5 to the first communication passage 4 and the second communication passage 6. Furthermore, in this embodiment, the second protrusion 52b guides the fuel spray to the first communication passage 4 and the first intake-side communication passage 4a. This makes it easier to supply a fuel-rich mixture to the auxiliary-combustion chamber 3.

[0025] As shown in FIG. 5, when the auxiliary combustion chamber type internal combustion engine 1 is in a high-load operating state, an in-cylinder flow occurs. In this embodiment, for example, a counterclockwise in-cylinder flow (see arrow R in FIG. 5) occurs. In such a case, the first injection F1 and the second injection F2 are swept away by the in-cylinder flow. At this time, the first injection F1 is directed toward the first intake-side communicating passage 4a, and the second injection F2 is directed toward the first communicating passage 4. As a result, a fuel-rich mixture is supplied to the first communicating passage 4 and the first intake-side communicating passage 4a. As a result, a fuel-rich mixture is likely to be supplied to the auxiliary combustion chamber 3. That is, as described above, by injecting the first injection F1 and the second injection F2, the fuel injection valve 9 can at least introduce the mixture into the first communicating passage 4 even when an in-cylinder flow occurs. This makes it possible to prevent the fuel concentration in the auxiliary combustion chamber 3 from becoming lean.

[0026] In this embodiment, the first communication passage 4, the second communication passage 6, the first intake-side communication passage 4a, the second intake-side communication passage 6a, and the four fourth communication passages 17 (hereinafter sometimes referred to as "each communication passage" in the specification) are arranged at equal intervals. That is, the communication passages are arranged at 45-degree intervals. However, the communication passages may be arranged at any intervals as long as the angle α is within 45 degrees and the angle β is within 45 degrees.

[0027] As shown in FIG. 6, the first spray axis F1x of the first spray F1 intersects the auxiliary combustion chamber wall 5 between the first communication passage 4 and the third communication passage 7. The second spray axis F2x of the second spray F2 intersects the auxiliary combustion chamber wall 5 between the second communication passage 6 and the third communication passage 7. The cross section of the auxiliary combustion chamber wall 5 in FIG. 6 is cross section II in FIG. 3. As shown in FIG. 6, the second spray F2 is directed between the second communication passage 6 and the third communication passage 7 and is inclined toward the second communication passage 6. More specifically, the second spray axis F2x is located between the center line C2 of the second communication passage 6 and the center line C3 of the third communication passage 7 and intersects the outer peripheral surface of the thin-walled portion 52c between the second communication passage 6 and the third communication passage 7. The second spray axis F2x is formed inclined toward the center line C2 of the second communication passage 6 and intersects the center line C2 of the second communication passage 6 on the intake side. That is, the fuel injector 9 injects the second injection so that the angle γ formed by the second spray axis F2x and the tangent line S1 at the position of the center line C2 of the second communication passage 6 is within 90 degrees. Although not shown, the first injection F1 is also injected in the same manner as the second injection F2.

[0028] Furthermore, the fuel spray of the second injection F2 is closer to the second communication passage 6 than to the third communication passage 7. More specifically, the second spray axis F2x intersects with the outer peripheral surface of the thin-walled portion 52c between the second communication passage 6 and the third communication passage 7 at a position where the center line C2 of the second communication passage 6 is closer than to the center line C3 of the third communication passage 7. Although not shown, the first injection F1 is also injected in the same manner as the second injection F2.

[0029] By forming the first injection F1 and the second injection F2 in this manner, the fuel sprays of the first injection F1 and the second injection F2 collide with the thin-walled portion 52c of the auxiliary-combustion-chamber wall 5 and diffuse. The diffused fuel spray flows toward the third communication passage 7. The fuel spray that flows into the third communication passage 7 collide with the first protrusion 52a and forms an air-fuel mixture around the third communication passage 7. Meanwhile, part of the fuel spray that collided with the thin-walled portion 52c flows toward the first communication passage 4 and the second communication passage 6. The fuel spray that flows into the first communication passage 4 and the second communication passage 6 collide with the second protrusion 52b and diffuses. As a result, a fuel-rich mixture is also formed around the first communication passage 4 and the second communication passage 6, and is supplied to the first communication passage 4 and the second communication passage 6. In this way, the fuel diffuses throughout the thin-walled portion 52c of the auxiliary-combustion-chamber wall 5.

[0030] As described above, in the auxiliary combustion chamber type internal combustion engine 1, fuel is diffused over the entire thin-walled portion 52c of the auxiliary combustion chamber wall 5, making it easy to form a fuel-rich mixture on the intake side and piston 8 side of the auxiliary combustion chamber wall 5. This allows a fuel-rich mixture to be supplied to the auxiliary combustion chamber 3 from the first communication passage 4, the second communication passage 6, and the third communication passage 7. Furthermore, in this embodiment, even if in-cylinder flow occurs, a fuel-rich mixture can be supplied to at least the first communication passage 4. This prevents the fuel concentration of the mixture in the auxiliary combustion chamber 3 from becoming lean. As a result, ignition ability in the auxiliary combustion chamber 3 is improved. The mixture supplied to the auxiliary combustion chamber 3 is ignited by the ignition device 10 to form a flame. The flame in the auxiliary combustion chamber 3 passes through each communication passage and is injected into the main combustion chamber 2 as a jet flame. In this embodiment, because a fuel-rich mixture is supplied to the auxiliary combustion chamber 3, the jet flame becomes stronger. It should be noted that the rich mixture around the auxiliary combustion chamber 3 does not necessarily mean only a rich mixture that is richer than the stoichiometric air-fuel ratio, but it may be a mixture with a stoichiometric air-fuel ratio or a lean mixture that is leaner than the stoichiometric air-fuel ratio as long as it is a mixture richer than the air-fuel ratio of the main combustion chamber 2.

[0031] As described above, according to the present disclosure, it is possible to provide an auxiliary combustion chamber type internal combustion engine 1 that can form an air-fuel mixture around the auxiliary combustion chamber 3 while taking into consideration the flow inside the cylinder.

[0032] <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 within the scope of the gist of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

[0033] (a) In the above embodiment, an example was described in which the side wall 51 was provided on the auxiliary combustion chamber wall 5, but the present disclosure is not limited to this. For example, the side wall 51 may be formed integrally with the cylinder head 12.

[0034] (b) In the above embodiment, the side wall 51 is cylindrical, but the present disclosure is not limited to this. The side wall 51 may have another cylindrical shape.

[0035] (c) In the above embodiment, the auxiliary combustion chamber wall 5 has been described as having a thin portion 52c and a thick portion 52d, but the present disclosure is not limited to this. For example, as shown in FIG. 7, a first protrusion 52a and a second protrusion 52b may be disposed on a portion of the auxiliary combustion chamber wall 5.

[0036] (d) In the above embodiment, two injections, the first injection F1 and the second injection F2, have been described as an example, but the present disclosure is not limited to this. The fuel injection valve 9 may have two or more injection holes. For example, if the fuel injection valve 9 has four injection holes, the spray axis of the third injection may be arranged to intersect with the auxiliary combustion chamber wall 5 between the first communication passage 4 and the first intake side communication passage 4a. The spray axis of the fourth injection may be arranged to intersect with the auxiliary combustion chamber wall 5 between the second communication passage 6 and the second intake side communication passage 6a. [Explanation of symbols]

[0037] 1: Pre-chamber internal combustion engine, 2: Main combustion chamber, 3: Pre-combustion chamber 4: First communication passage, 5: Pre-combustion chamber wall, 6: Second communication passage, 7: Third communication passage 8: Piston, 9: Fuel injection valve, 11a: Cylinder 52a: first convex portion, 52b: second convex portion, C5: central axis F1: 1st jet, F1x: 1st spray axis, F2: 2nd jet, F2x: 2nd spray axis

Claims

1. A main combustion chamber; an auxiliary combustion chamber arranged separated from the main combustion chamber via a partition wall; a fuel injection valve having a first injection and a second injection that is injected in a direction different from that of the first injection; a first communication passage provided in the partition wall and communicating between the main combustion chamber and the auxiliary combustion chamber; a second communication passage that communicates the main combustion chamber with the auxiliary combustion chamber in a direction different from that of the first communication passage; Equipped with The first injection is injected in a direction intersecting the first communication passage, The second injection is injected in a direction intersecting the second communication passage. Pre-chamber internal combustion engine.

2. the first communication passage and the second communication passage are adjacent to each other, and a central axis of the fuel injection valve is positioned at a partition wall between the first communication passage and the second communication passage; 2. The pre-combustion chamber type internal combustion engine according to claim 1.

3. a first spray axis of the first jet and a second spray axis of the second jet intersect with the partition wall between the first communication passage and the second communication passage; 2. The pre-combustion chamber type internal combustion engine according to claim 1.

4. A piston that slides in a cylinder; a third communication passage that communicates the main combustion chamber with the auxiliary combustion chamber toward the piston; Furthermore, the first communication passage and the second communication passage are formed toward the cylinder, a first spray axis of the first jet intersects with the partition wall between the first communication passage and the third communication passage, a second spray axis of the second jet intersects with the partition wall between the second communication passage and the third communication passage; 2. The pre-combustion chamber type internal combustion engine according to claim 1.

5. The fuel injection valve further includes a guide portion for guiding the spray injected from the fuel injection valve.

5. The pre-combustion chamber type internal combustion engine according to claim 1.

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