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 4 separated from the main combustion chamber via a partition wall. The sub-combustion chamber has a first sub-combustion chamber 4a, and a second sub-combustion chamber 4b 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 18 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 20 directed toward the piston and communicating with the main combustion chamber is provided. A diameter of the first communication passage is larger than a diameter of the second communication passage.SELECTED DRAWING: Figure 2

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 separated from the main combustion chamber by a wall, the auxiliary combustion chamber having a first auxiliary combustion chamber and a second auxiliary combustion chamber separated from the first auxiliary combustion chamber by an inner wall and located closer to the main combustion chamber than the first auxiliary combustion chamber, the ignition device being located in the first auxiliary combustion chamber, the inner wall being provided with a first communication passage connecting the first auxiliary combustion chamber and the second auxiliary combustion chamber, and the second auxiliary combustion chamber being provided with a second communication passage connecting with the main combustion chamber towards the piston, the diameter of the first communication passage being larger than the diameter of the second communication passage. [Effects of the Invention]

[0007] According to this configuration, the air-fuel mixture is supplied from the second auxiliary combustion chamber to the first auxiliary combustion chamber. Because the diameter of the first communication passage is larger than the diameter of the second communication passage, it is easy to supply the air-fuel mixture to the first auxiliary combustion chamber. The air-fuel mixture supplied to the first auxiliary combustion chamber is ignited by an ignition device 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. In this way, 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, embodiments 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 first auxiliary combustion chamber 4a is provided in the cylinder head 12. The auxiliary combustion chamber wall 5 has an inner wall 51, a first wall 52, and a second wall 53. The second auxiliary combustion chamber 4b is arranged separated by the inner wall 51 and is located closer to the main combustion chamber 2 than the first auxiliary combustion chamber 4a. The first wall 52 is located on the cylinder head side (top dead center side) in the sliding direction P of the piston 8 and protrudes from the inner wall 51 toward the main combustion chamber 2. The second wall 53 is located adjacent to the first wall 52 on the piston 8 side (bottom dead center side) in the sliding direction P of the first wall 52 (see FIG. 1). In this embodiment, the inner wall 51 and the first wall 52 are integrally formed.

[0014] The first wall 52 includes a first flange 52a. The second wall 53 includes a second flange 53a. The first flange 52a and the second flange 53a are fixed by bolts or the like, connecting the first wall 52 and the second wall 53. The first wall 52 of this embodiment has a hollow hemispherical shape that is open on the bottom dead center side in the sliding direction P. The first flange 52a is formed around the opening. The second wall 53 has a hollow hemispherical shape that is open on the top dead center side in the sliding direction P. The second flange 53a is formed around the opening.

[0015] The auxiliary combustion chamber 4 is provided with a first communication passage 18, a second communication passage 20, a third communication passage 22, and a fourth communication passage 24. The first communication passage 18 is provided in the inner wall 51 and connects the first auxiliary combustion chamber 4a and the second auxiliary combustion chamber 4b. The second communication passage 20 is provided in the second auxiliary combustion chamber 4b and connects the second auxiliary combustion chamber 4b and the main combustion chamber 2 toward the piston 8. The third communication passage 22 is provided in the second auxiliary combustion chamber 4b and connects the second auxiliary combustion chamber 4b and the main combustion chamber 2 toward the cylinder head 12. The fourth communication passage 24 is provided in the second auxiliary combustion chamber 4b and connects the second auxiliary combustion chamber 4b and the main combustion chamber 2 toward the cylinder 10a.

[0016] The diameter D1 of the first communication passage 18 is larger than the diameter D2 of the second communication passage 20. The diameter D4 of the fourth communication passage 24 is larger than the diameter D3 of the third communication passage 22.

[0017] In this embodiment, the center line C1 of the first communication passage 18 overlaps with the center line C2 of the second communication passage when viewed in the sliding direction P. Furthermore, the center line C1 of the first communication passage 18 and the center line C2 of the second communication passage overlap with the center line (not shown) of the cylinder 10a. That is, the second communication passage 20 is disposed on the center line of the cylinder 10a.

[0018] The second auxiliary combustion chamber 4b has a largest diameter D5 at the center in the sliding direction P of the piston 8. In this embodiment, the diameter D5 is the same as the diameter of the openings of the first wall 52 and the second wall 53. The diameter D5 is larger than the diameter D1 of the first communication passage 18.

[0019] 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.

[0020] 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.

[0021] As shown in FIG. 3(a), the auxiliary combustion chamber type internal combustion engine 1 configured as 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. At this time, the fuel injection valve 9 injects fuel so that the injection axis F is closer to the piston 8 in the sliding direction P than the second flange 53a. This makes it easier for fuel to be supplied to the fourth communication passage 24. As a result, an air-fuel mixture is easily formed in the second auxiliary combustion chamber 4b. Furthermore, the diameter D4 (see FIG. 2) of the fourth communication passage 24 is larger than the diameter D2 of the second communication passage 20. Therefore, fuel is easily supplied from the fourth communication passage 24 to the second auxiliary combustion chamber 4b. The air-fuel mixture that enters the second auxiliary combustion chamber 4b passes through the first communication passage 18 and enters the first auxiliary combustion chamber 4a.

[0022] 3(b), when the ignition device 6 ignites the spark plug 6a, the air-fuel mixture in the first auxiliary combustion chamber 4a is first ignited, and a jet flame is injected from the first communication passage 18. The air-fuel mixture in the second auxiliary combustion chamber 4b is ignited by the jet flame injected from the first communication passage 18. For this reason, the combustion energy is higher than when the air-fuel mixture is ignited by the ignition device 6.

[0023] As shown in Figure 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, the third communication passage 22, and the fourth communication passage 24. As shown in an enlarged view in Figure 3(c), the third communication passage 22 injects a jet flame toward the cylinder head 12. This allows the jet flame to be supplied to the vicinity of the ridgeline of the pent roof. As a result, combustion near the ridgeline of the pent roof, where combustion tends to be slow, can be promoted.

[0024] Furthermore, 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 flames injected from the second communication passage 20, the third communication passage 22, and the fourth communication passage 24 is high. As a result, the momentum of the jet flames is stronger than when ignition is performed by the ignition device 6.

[0025] 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.

[0026] <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.

[0027] (a) In the above embodiment, the auxiliary combustion chamber wall 5 is described as being made up of two hemispherical members, the first wall 52 and the second wall 53, but the present disclosure is not limited to this. The auxiliary combustion chamber wall 5 may be a single hollow spherical member. In this case, instead of the first flange 52a and the second flange 53a, a protrusion protruding from the auxiliary combustion chamber wall 5 toward the cylinder 10a may be provided.

[0028] (b) In the above embodiment, the auxiliary combustion chamber wall 5 has been described using an example in which the first wall 52 is formed in a hemispherical shape, but the present disclosure is not limited to this. As shown in FIG. 4, the auxiliary combustion chamber wall 5 may be cylindrical, for example. In this case, the third communication passage 22 may be provided in the first wall 52 so as to be inclined toward the piston 8 side in the sliding direction P (see FIG. 1) as it approaches the center of the cylinder 10a. By forming the third communication passage 22 in this manner, the third communication passage 22 can inject a jet flame toward the cylinder head 12. [Explanation of symbols]

[0029] 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: Pre-combustion chamber wall 6:Ignition system, 8: Piston, 10a: Cylinder, 12: Cylinder head 18: 1st communication passage, 20: 2nd communication passage, 22: 3rd communication passage, 24: 4th communication passage 51: inner wall, 52: first wall, 52a: first flange 53: second wall, 53a: second flange C1: Center line of the first connecting passage C2: Center line of second communication passage P: Sliding direction

Claims

1. A piston that slides in a cylinder; An ignition device; A main combustion chamber; an auxiliary combustion chamber disposed apart from the main combustion chamber via a 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, The diameter of the first communication passage is larger than the diameter of the second communication passage. Pre-chamber internal combustion engine.

2. Further comprising a cylinder head, The auxiliary combustion chamber is provided in the cylinder head, The second auxiliary combustion chamber has a third communication passage communicating with the main combustion chamber in a direction toward the cylinder head.

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

3. the second auxiliary combustion chamber has a fourth communication passage communicating with the main combustion chamber in a direction toward the cylinder, The fourth communication passage has a larger diameter than the third communication passage.

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

4. The second auxiliary combustion chamber has a diameter at a center portion in a sliding direction of the piston that is larger than a diameter of the first communication passage.

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

5. The second auxiliary combustion chamber has a first wall disposed on the cylinder head side in the sliding direction of the piston, a second wall disposed on the piston side of the first wall, and a flange connecting the first wall and the second wall and protruding beyond the first wall and the second wall toward the cylinder.

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

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