Auxiliary chamber type internal combustion engine

Abstract

To provide an auxiliary chamber type internal combustion engine which can enhance the momentum of jet flame.SOLUTION: An auxiliary chamber type internal combustion engine includes a piston sliding within a cylinder, an ignition device, a main combustion chamber, and a sub-combustion chamber separated from the main combustion chamber via a partition wall. The sub-combustion chamber has a first sub-combustion chamber, and a second sub-combustion chamber separated from the first sub-combustion chamber via an inner wall and disposed closer to the main combustion chamber than the first sub-combustion chamber. The ignition device is disposed in the first sub-combustion chamber. In the inner wall, A first communication passage communicating with the first sub-combustion chamber and the second sub-combustion chamber is provided. In the second sub-combustion chamber, a second communication passage directed toward the piston and communicating with the main combustion chamber is provided. A center line of the first communication passage is provided off-set with respect to a center line of 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 comprises a main combustion chamber and a pre-combustion chamber, with an ignition device and a fuel injection valve disposed in the pre-combustion chamber. The pre-combustion chamber type internal combustion engine of Patent Document 1 generates an air-fuel mixture in the pre-combustion chamber and ignites this air-fuel mixture 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] Japanese Patent Application Laid-Open No. 2007-85181 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, passive-type pre-chamber internal combustion engines have been developed, in which a fuel injection valve is placed in the main combustion chamber or intake port, and an air-fuel mixture is supplied from the main combustion chamber to the pre-chamber, where it is burned. In such passive-type pre-chamber internal combustion engines, uneven flames are likely to occur due to the richness of the air-fuel mixture near the ignition device. Flame unevenness can weaken the intensity of the jet flame injected from the connecting passage. Weak jet flame intensity can also result in slow combustion near the center of the cylinder. Slow combustion can lead to issues such as a longer combustion period and increased emissions of unburned hydrocarbons.

[0005] An object of the present disclosure is to provide a pre-chamber internal combustion engine that can increase the intensity of a jet flame. [Means for solving the problem]

[0006] The auxiliary combustion chamber type internal combustion engine according to the present disclosure comprises a piston that slides within a cylinder, an ignition device, a main combustion chamber, and an auxiliary combustion chamber arranged via a partition wall from the main combustion chamber, the auxiliary combustion chamber having a first auxiliary combustion chamber and a second auxiliary combustion chamber arranged separated from the first auxiliary combustion chamber via an inner wall and arranged closer to the main combustion chamber than the first auxiliary combustion chamber, the ignition device is arranged in the first auxiliary combustion chamber, the inner wall is provided with a first communication passage connecting the first auxiliary combustion chamber and the second auxiliary combustion chamber, the second auxiliary combustion chamber is provided with a second communication passage that connects with the main combustion chamber towards the piston, and the center line of the first communication passage is offset from the center line of the second communication passage. [Effects of the Invention]

[0007] According to this configuration, first, the ignition device ignites the air-fuel mixture supplied to the first auxiliary combustion chamber to form a flame. The flame formed in the first auxiliary combustion chamber is injected as a jet flame from the first communication passage into the second auxiliary combustion chamber. The air-fuel mixture in the second auxiliary combustion chamber is ignited by the jet flame injected from the first communication passage. The flame in the second auxiliary combustion chamber is injected from the second communication passage. At this time, because the first communication passage and the second communication passage are offset, the flame injected from the first communication passage is prevented from passing through the second communication passage. This makes it easier to ignite the air-fuel mixture in the second auxiliary combustion chamber. The second auxiliary combustion chamber is ignited by a jet flame with higher energy than that of the ignition device. As a result, the momentum of the flame injected from the second communication passage is higher than that of an auxiliary combustion chamber-type internal combustion engine having only a first auxiliary combustion chamber. [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 an enlarged view of a portion of a pre-combustion chamber according to an embodiment of the present disclosure. [Figure 3] 1 is a diagram showing an injection pattern of an internal combustion engine with a pre-chamber according to an embodiment of the present disclosure; [Figure 4] FIG. 10 is an enlarged view of a portion of the auxiliary combustion chamber according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings.

[0010] As shown in FIG. 1, the auxiliary combustion chamber type internal combustion engine 1 includes a main combustion chamber 2, an auxiliary combustion chamber 4, an ignition device 6, a piston 8, and a fuel injection valve 9.

[0011] The main combustion chamber 2 is a space surrounded by the cylinder 10a of the cylinder block 10, 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 intake port 12a in this embodiment forms a tumble flow or a swirl flow in the main combustion chamber 2. 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 4 protrudes from the cylinder head 12 toward the main combustion chamber 2, and is separated from the main combustion chamber 2 by an auxiliary combustion chamber wall (an example of a partition wall) 5. The auxiliary combustion chamber 4 of this embodiment is located adjacent to the main combustion chamber 2 at the top of the pent roof shape, and has a space surrounded by the auxiliary combustion chamber wall 5.

[0013] As shown in Fig. 2, the auxiliary combustion chamber 4 has a first auxiliary combustion chamber 4a and a second auxiliary combustion chamber 4b. The auxiliary combustion chamber wall 5 has a first auxiliary combustion chamber wall 5a and a second auxiliary combustion chamber wall 5b. In this embodiment, the first auxiliary combustion chamber 4a is a space surrounded by the first auxiliary combustion chamber wall 5a. The second auxiliary combustion chamber 4b is a space surrounded by the second auxiliary combustion chamber wall 5b. The second auxiliary combustion chamber 4b is separated from the first auxiliary combustion chamber 4a by an inner wall formed as a first bottom wall 52 of the first auxiliary combustion chamber wall 5a. The second auxiliary combustion chamber 4b is located closer to the main combustion chamber 2 (closer to the piston 8 in the sliding direction) than the first auxiliary combustion chamber 4a.

[0014] The first auxiliary combustion chamber wall 5a has a first side wall 51 and a first bottom wall 52. The second auxiliary combustion chamber wall 5b has a second side wall 53 and a second bottom wall 54. In this embodiment, the first side wall 51 and the second side wall 53 are formed in a cylindrical shape. However, the first side wall 51 and the second side wall 53 do not necessarily have to be cylindrical and may have another cylindrical shape. The first side wall 51 is disposed in close contact with the inner circumferential surface of the second side wall 53. The first bottom wall 52 is disposed at the portion where the first side wall 51 and the second side wall 53 overlap. In this embodiment, the first bottom wall 52 is formed in a cylindrical shape. The second bottom wall 54 is formed in a hemispherical shape. However, the first bottom wall 52 may be formed in a hemispherical shape, for example. The second bottom wall 54 may be formed in a cylindrical shape, for example.

[0015] In this way, by making the auxiliary combustion chamber 4 a double structure with the first auxiliary combustion chamber wall 5a and the second auxiliary combustion chamber wall 5b, it is easy to manufacture a structure in which the auxiliary combustion chamber 4 is divided in the sliding direction of the piston 8 (see arrow P in Figure 1).

[0016] The first auxiliary combustion chamber 4a is provided with a first communication passage 18 that connects the first auxiliary combustion chamber 4a and the second auxiliary combustion chamber 4b. In this embodiment, the first communication passage 18 is provided in the first bottom wall (an example of an inner wall) 52, penetrating the first bottom wall 52 and connecting the first auxiliary combustion chamber 4a and the second auxiliary combustion chamber 4b.

[0017] The second auxiliary combustion chamber 4b is provided with a second communication passage 20 and a third communication passage 22. The second communication passage 20 connects the second auxiliary combustion chamber 4b to the main combustion chamber 2 toward the piston 8. In this embodiment, the second communication passage 20 passes straight through the hemispherical second bottom wall 54 in the sliding direction of the piston 8, and connects the second auxiliary combustion chamber 4b to the main combustion chamber 2.

[0018] The third communication passage 22 connects the second auxiliary combustion chamber 4b and the main combustion chamber 2 toward the cylinder 10a. In this embodiment, the third communication passage 22 penetrates the hemispherical second bottom wall 54 toward the cylinder 10a, connecting the second auxiliary combustion chamber 4b and the main combustion chamber 2. A plurality of third communication passages 22 are provided along the circumferential direction of the second bottom wall 54. In this embodiment, a total of six third communication passages 22 are provided: three on the intake side where the fuel injection valve 9 is located and three on the exhaust side. However, the number of third communication passages 22 may be changed as appropriate.

[0019] The center line C1 of the auxiliary combustion chamber 4 is inclined relative to the center line C2 of the cylinder 10a. That is, the center line C1 of the auxiliary combustion chamber 4 is inclined relative to the sliding direction of the piston 8. In this embodiment, the center line C1 of the auxiliary combustion chamber 4 is inclined relative to the center line C2 of the cylinder 10a toward the intake side where the fuel injection valve 9 is located.

[0020] The diameter D1 of the first communication passage 18 is larger than the diameter D2 of the second communication passage 20. The diameter D3 of the third communication passage 22 is the same as the diameter D2 of the second communication passage 20.

[0021] The center line C3 of the first communication passage 18 is offset from the center line C4 of the second communication passage 20. In this embodiment, the center line C3 of the first communication passage 18 is offset toward the exhaust side from the center line C4 of the second communication passage 20. The center line C3 of the first communication passage 18 extends in the sliding direction of the piston 8. That is, the first communication passage 18 penetrates in the sliding direction of the piston 8. Therefore, the center line C3 of the first communication passage 18 is inclined with respect to the center line C1 of the auxiliary combustion chamber 4. The first communication passage 18 is offset on the opposite side of the direction in which the center line C1 of the auxiliary combustion chamber 4 is inclined. The center line C4 of the second communication passage 20 extends in the sliding direction of the piston 8 and is the same as the center line C2 of the cylinder 10a. Therefore, the center line C3 of the first communication passage 18 is parallel to the center line C4 of the second communication passage 20.

[0022] The ignition device 6 is disposed in the first auxiliary combustion chamber 4a. The ignition device 6 has an ignition coil (not shown) and an ignition plug 6a. A center electrode 6b and a side electrode 6c of the ignition plug 6a protrude into the first auxiliary combustion chamber 4a. In this embodiment, the center electrode 6b is disposed approximately in the center of the first auxiliary combustion chamber 4a. However, the center electrode 6b may be disposed offset from the approximately center of the first auxiliary combustion chamber 4a toward the cylinder 10a.

[0023] As shown in FIG. 1, a piston 8 is housed in a cylinder 10a and slides within the cylinder 10a. The piston 8 surrounds the main combustion chamber 2 from below. A fuel injection valve 9 injects fuel toward the main combustion chamber 2 and the auxiliary combustion chamber 4, forming an air-fuel mixture in the main combustion chamber 2 and the auxiliary combustion chamber 4. In this embodiment, the fuel injection valve 9 is a direct injection type that injects fuel directly into the main combustion chamber 2. However, the fuel injection valve 9 may also be a port injection type.

[0024] As shown in FIG. 3(a), the auxiliary combustion chamber type internal combustion engine 1 configured as described above injects fuel using the fuel injection valve 9 to form an air-fuel mixture in the main combustion chamber 2 and the auxiliary combustion chamber 4. The air-fuel mixture passes through the second communication passage 20 and the third communication passage 22 and enters the second auxiliary combustion chamber 4b. The air-fuel mixture that has entered the second auxiliary combustion chamber 4b collides with the first bottom wall 52, promoting mixing within the second auxiliary combustion chamber 4b. The air-fuel mixture then passes through the first communication passage 18 and enters the first auxiliary combustion chamber 4a. Because the first communication passage 18 is offset to the opposite side of the inclination direction of the center line C1 of the auxiliary combustion chamber 4, a vertical vortex (tumble flow, see arrow F) of the mixture is likely to form in the first auxiliary combustion chamber 4a. As a result, a uniform air-fuel mixture is likely to be formed in the first auxiliary combustion chamber 4a.

[0025] 3(b), when the ignition device 6 ignites the spark plug 6a, first, the air-fuel mixture in the first auxiliary combustion chamber 4a is ignited, and a jet flame is injected from the first communication passage 18. At this time, the center line C3 (see FIG. 2) of the first communication passage 18 is offset from the center line C4 (see FIG. 2) of the second communication passage 20, so that the jet flame is prevented from directly ejecting from the first communication passage 18 into the second communication passage 20. This makes it easier for the air-fuel mixture in the second auxiliary combustion chamber 4b to be ignited by the jet flame injected from the first communication passage 18.

[0026] As shown in FIG. 3(c), when the air-fuel mixture in the second auxiliary combustion chamber 4b is ignited, a jet flame is injected from the second communication passage 20 and the third communication passage 22. The air-fuel mixture in the second auxiliary combustion chamber 4b is ignited by the jet flame injected from the first communication passage 18. Therefore, the combustion energy is higher than when ignition is performed by the ignition device 6. As a result, the energy of the jet flame injected from the second communication passage 20 and the third communication passage 22 is also high. As a result, the momentum of the jet flame is stronger than when ignition is performed by the ignition device 6.

[0027] As described above, according to the present disclosure, it is possible to provide a pre-chamber internal combustion engine 1 that can increase the momentum of the jet flame.

[0028] <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.

[0029] (a) In the above embodiment, an example in which the first sub-combustion-chamber wall 5a is provided has been described, but the present disclosure is not limited to this. For example, the first side wall 51 may be formed integrally with the cylinder head 12. The first bottom wall 52 may be formed integrally with the second sub-combustion-chamber wall 5b.

[0030] (b) In the above embodiment, the center line C3 of the first communication passage 18 extends in the sliding direction of the piston 8, but the present disclosure is not limited to this. As shown in Fig. 4, the center line C3 of the first communication passage 18 may extend in a direction toward the center line C4 of the second communication passage 20. [Explanation of symbols]

[0031] 1: Pre-chamber internal combustion engine, 2: Main combustion chamber 4: auxiliary combustion chamber, 4a: first auxiliary combustion chamber, 4b: second auxiliary combustion chamber 5: auxiliary combustion chamber wall, 5a: first auxiliary combustion chamber wall, 5b: second auxiliary combustion chamber wall 6: Ignition device, 8: Piston, 9: Fuel injection valve 10a: cylinder, 18: first communication passage, 20: second communication passage C1: Center line of the auxiliary combustion chamber C2: Center line of the cylinder C3: Center line of the first connecting passage C4: Center line of the second connecting passage

Claims

1. A piston that slides in a cylinder; An ignition device; A main combustion chamber; an auxiliary combustion chamber disposed between the main combustion chamber and the auxiliary combustion chamber via a partition wall; Equipped with The auxiliary combustion chamber includes a first auxiliary combustion chamber, a second auxiliary combustion chamber disposed apart from the first auxiliary combustion chamber via an inner wall and closer to the main combustion chamber than the first auxiliary combustion chamber; and the ignition device is disposed in the first auxiliary combustion chamber, a first communication passage that communicates the first auxiliary combustion chamber with the second auxiliary combustion chamber is provided in the inner wall; The second auxiliary combustion chamber is provided with a second communication passage that communicates with the main combustion chamber toward the piston, a center line of the first communication passage is offset from a center line of the second communication passage; Pre-chamber internal combustion engine.

2. The diameter of the first communication passage is larger than the diameter of the second communication passage.

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

3. The centerline of the auxiliary combustion chamber is inclined with respect to the centerline of the cylinder.

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

4. The first communication passage is provided offset to the opposite side with respect to the direction in which the center line of the auxiliary combustion chamber inclines.

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

5. The center line of the first communication passage is inclined with respect to the center line of the auxiliary combustion chamber.

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

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