Auxiliary chamber type internal combustion engine

Abstract

To provide an auxiliary chamber type internal combustion engine which can reduce unburned hydrocarbon while suppressing cooling loss.SOLUTION: An auxiliary chamber type internal combustion engine includes a main combustion chamber, a sub-combustion chamber disposed across a partition wall from the main combustion chamber, and a communication passage disposed in the partition wall. The communication passage has a first communication passage disposed in a lean side of the main combustion chamber in which air-fuel mixture becomes lean, and a second communication passage disposed in a rich side of the main combustion chamber in which the air-fuel mixture becomes rich. A length of the first communication passage is longer than a length 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 has a main combustion chamber and a pre-combustion chamber, and ignites the air-fuel mixture in the main combustion chamber by injecting a jet flame from the pre-combustion chamber toward the main combustion chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-319961 A Summary of the Invention [Problem to be solved by the invention]

[0004] In such pre-chamber internal combustion engines, the mixture may become rich or lean in the main combustion chamber. In the lean region, the flame does not advance completely, and unburned hydrocarbons are likely to be produced. In the lean region, unburned hydrocarbons can be reduced by strengthening the jet flame penetration power. However, if the jet flame penetration power is strengthened in all regions outside the lean region, the jet flame impingement on the cylinder will also be strengthened, resulting in increased cooling loss.

[0005] An object of the present disclosure is to provide a pre-chamber internal combustion engine that can reduce unburned hydrocarbons while suppressing cooling loss. [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 arranged with a partition wall between it and the main combustion chamber, and a communication passage arranged in the partition wall, the communication passage having a first communication passage arranged on the lean side of the main combustion chamber where the mixture becomes lean, and a second communication passage arranged on the rich side of the main combustion chamber where the mixture becomes rich, and the length of the first communication passage is longer than the length of the second communication passage.

[0007] With this pre-chamber internal combustion engine, a jet flame with strong penetration power can be injected from the first communication passage. This reduces unburned hydrocarbons in the lean region. Meanwhile, a jet flame with weaker penetration power than the jet flame injected from the first communication passage is injected from the second communication passage. This reduces cooling loss in regions other than the lean region.

[0008] Another auxiliary combustion chamber type internal combustion engine according to the present disclosure includes a main combustion chamber, an auxiliary combustion chamber arranged with a partition wall between it and the main combustion chamber, a communication passage arranged in the partition wall, and a piston that slides within a cylinder surrounding the main combustion chamber, and there are multiple communication passages, and the distance of the communication passage on the side where a protrusion is arranged on the top surface of the piston is longer than the communication passage on the side where no protrusion is arranged.

[0009] In this pre-chamber internal combustion engine, the jet flame injected from the communication passage on the side with the protruding portion has strong penetration power. This reduces unburned hydrocarbons in the gap between the protruding portion and the cylinder. Meanwhile, the jet flame with weaker penetration power is injected from the other communication passage. This suppresses the collision of the jet flame with the cylinder. As a result, this pre-chamber internal combustion engine can reduce cooling loss.

[0010] Yet another auxiliary combustion chamber type internal combustion engine according to the present disclosure comprises a main combustion chamber, an auxiliary combustion chamber arranged with a partition wall between it and the main combustion chamber, a communication passage arranged in the partition wall, and a piston that slides within a cylinder surrounding the main combustion chamber, and there are a plurality of communication passages, and the farther a communication passage from the cylinder is, the longer the distance of the communication passage.

[0011] In this pre-chamber internal combustion engine, the farther the connecting passage is from the cylinder, the stronger the penetration power of the jet flame injected from the connecting passage. This promotes combustion with the jet flame having stronger penetration power, reducing unburned hydrocarbons. Furthermore, the closer the connecting passage is from the cylinder, the less the jet flame impinges on the cylinder. As a result, this pre-chamber internal combustion engine can reduce cooling loss. [Effects of the Invention]

[0012] According to the above-described pre-chamber internal combustion engine, it is possible to reduce unburned hydrocarbons while suppressing cooling loss. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing a pre-combustion chamber type internal combustion engine according to a first embodiment of the present disclosure; [Figure 2] FIG. 2 is an enlarged cross-sectional view of an auxiliary combustion chamber according to the first embodiment of the present disclosure. [Figure 3] 1 is a diagram showing an injection pattern of an internal combustion engine with a pre-combustion chamber according to a first embodiment of the present disclosure; [Figure 4] FIG. 6 is a cross-sectional view of an auxiliary combustion chamber according to a second embodiment of the present disclosure. [Figure 5] FIG. 10 is a cross-sectional view of an auxiliary combustion chamber according to a third embodiment of the present disclosure. [Figure 6] FIG. 10 is a cross-sectional view of a pre-combustion chamber according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] First Embodiment Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings.

[0015] As shown in FIG. 1, the auxiliary combustion chamber type internal combustion engine 1 includes a main combustion chamber 2, an auxiliary combustion chamber 3, a communication passage 4, an ignition device 6, a piston 8, and a fuel injection valve 9.

[0016] 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 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).

[0017] The auxiliary combustion chamber 3 is located adjacent to the main combustion chamber 2 at the top of the pent roof shape, and has a space surrounded by an auxiliary combustion chamber wall 5. The auxiliary combustion chamber 3 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. In this embodiment, the auxiliary combustion chamber 3 is positioned offset toward the exhaust side with respect to the center line C1 of the cylinder 10a. Therefore, a first distance D1 from the center line C2 of the auxiliary combustion chamber 3 to the intake-side cylinder 10a is longer than a second distance D2 from the center line C2 of the auxiliary combustion chamber 3 to the exhaust-side cylinder 10a.

[0018] The auxiliary combustion chamber wall 5 has a side wall 51 and a bottom wall 52. In this embodiment, the side wall 51 has a cylindrical shape. The bottom wall 52 has a hollow hemispherical shape. The side wall 51 may be molded integrally with the cylinder head 12.

[0019] The communication passage 4 is disposed in the auxiliary combustion chamber wall 5. In this embodiment, the communication passage 4 is disposed in the bottom wall 52. As shown in FIG. 2, the communication passage 4 has a first communication passage 4a, a second communication passage 4b, and a third communication passage 4c.

[0020] The first communication passage 4a is arranged on the side of the main combustion chamber 2 where the fuel concentration of the mixture becomes lean. In this embodiment, the fuel injection valve 9 is arranged on the intake side. For this reason, the mixture in the space on the intake side of the main combustion chamber 2 tends to become lean. Therefore, in this embodiment, the first communication passage 4a is arranged on the intake side of the bottom wall 52. The bottom wall 52 has a protrusion 53 on its outer periphery that protrudes toward the main combustion chamber 2, and the first communication passage 4a passes through the protrusion 53. The length of the multiple communication passages 4 in this embodiment can be changed by changing the height of the protrusion 53. Three first communication passages 4a are provided on the intake side of the bottom wall 52.

[0021] The second communication passages 4b are arranged on the side of the main combustion chamber 2 where the fuel concentration of the mixture becomes rich. The mixture in the space on the exhaust side of the main combustion chamber 2 tends to become rich. For this reason, in this embodiment, the second communication passages 4b are arranged on the exhaust side of the bottom wall 52. A protrusion 54 is provided on the outer periphery of the bottom wall 52, and the second communication passages 4b pass through the protrusion 54. Three second communication passages 4b are provided on the exhaust side of the bottom wall 52.

[0022] The third communication passage 4c is arranged facing the piston 8. More specifically, the third communication passage 4c is arranged along the center line C2 of the auxiliary combustion chamber 3 from the bottom wall 52 toward the bottom dead center in the sliding direction P.

[0023] The length L1 of the first communication passage 4a is longer than the length L2 of the second communication passage 4b. The length L3 of the third communication passage 4c is shorter than the length L1 of the first communication passage 4a and the length L2 of the second communication passage 4b.

[0024] As shown in Fig. 2, the ignition device 6 is disposed in the auxiliary combustion chamber 3. 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 auxiliary combustion chamber 3. In this embodiment, the center electrode 6b is disposed on the center line C2 of the auxiliary combustion chamber 3. However, the center electrode 6b may be disposed offset from the center line C2 of the auxiliary combustion chamber 3.

[0025] As shown in Fig. 1, the piston 8 is housed in the cylinder 10a and slides within the cylinder 10a. The piston 8 surrounds the main combustion chamber 2 from below. The piston 8 has protrusions 8a. In this embodiment, the protrusions 8a are provided on the intake side and the exhaust side around the top surface of the piston 8.

[0026] The fuel injection valve 9 injects fuel toward the main combustion chamber 2 and the auxiliary combustion chamber 3, forming a mixture of air and fuel in the main combustion chamber 2 and the auxiliary combustion chamber 3. In this embodiment, the fuel injection valve 9 is of a direct injection type that injects fuel directly into the main combustion chamber 2. However, the fuel injection valve 9 may also be of a port injection type.

[0027] In the auxiliary combustion chamber type internal combustion engine 1 configured as above, fuel is injected by the fuel injection valve 9 to form an air-fuel mixture in the main combustion chamber 2 and the auxiliary combustion chamber 3. At this time, the fuel is injected toward the exhaust side, and the flow inside the cylinder tends to make the air-fuel ratio of the mixture on the exhaust side rich. The ignition device 6 ignites the air-fuel mixture in the auxiliary combustion chamber 3, forming a flame in the auxiliary combustion chamber 3. The flame formed in the auxiliary combustion chamber 3 becomes a jet flame and is injected from the connecting passage 4.

[0028] The length L1 of the first communication passage 4a is longer than the length L2 of the second communication passage 4b ​​(see FIG. 3). As a result, the jet flame F1 injected from the first communication passage 4a has stronger penetration power than the jet flame F2 injected from the second communication passage 4b. In other words, the jet flame F1 is thinner and reaches farther than the jet flame F2. The jet flame F2 diffuses to a closer position than the jet flame F1.

[0029] The jet flame F1 has a strong penetration force. Therefore, the jet flame F1 promotes the combustion of a lean mixture in the lean region and reduces unburned hydrocarbons. The jet flame F2 spreads more than the jet flame F1. This reduces the collision of the jet flame F2 with the cylinder 10a, which is located at a second distance D2 (see FIG. 1) that is shorter than the first distance D1. As a result, this pre-chamber internal combustion engine 1 can reduce cooling loss caused by the collision of the jet flame F2 with the cylinder 10a. The jet flame F2 is injected outside the lean region (i.e., the stoichiometric region or the rich region). Therefore, even though the jet flame F2 has a weaker penetration force than the jet flame F1, combustion is sufficiently promoted and the emission of unburned hydrocarbons is suppressed.

[0030] Furthermore, as shown in Fig. 2, the length L3 of the third communication passage 4c is shorter than the length L1 of the first communication passage 4a and the length L2 of the second communication passage 4b. As shown in Fig. 3, this causes the jet flame F3 to have weaker penetration power than the jet flames F1 and F2, and to diffuse. This reduces the impact of the jet flame F3 on the top surface of the piston 8. As a result, this pre-chamber internal combustion engine 1 can reduce cooling loss.

[0031] Furthermore, the jet flames F1 and F2 injected onto the side of the piston 8 where the protruding portion 8a is located have stronger penetration power than the jet flame F3 injected onto the side where the protruding portion 8a is not located. This makes it easier for the jet flames F1 and F2 to reach the gap between the protruding portion 8a and the cylinder 10a. As a result, this pre-chamber internal combustion engine 1 can promote combustion all the way to the gap between the protruding portion 8a and the cylinder 10a, reducing unburned hydrocarbons.

[0032] Second Embodiment Next, a second embodiment will be described with reference to Fig. 4. In the second embodiment, only the differences from the first embodiment will be described.

[0033] As shown in Fig. 4, in the auxiliary combustion chamber type internal combustion engine 201 of the second embodiment, of the multiple communication passages 204 provided in the auxiliary combustion chamber 203, the communication passage 204a on the side where the protruding portion 208a of the piston 208 is located has a long length L201. The other communication passages 204b of the auxiliary combustion chamber type internal combustion engine 201 have a length L202 that is shorter than the length L201. The center line C202 of the auxiliary combustion chamber 203 coincides with the center line C201 of the cylinder 210a. The other configuration of the second embodiment is similar to that of the first embodiment.

[0034] According to this pre-chamber internal combustion engine 201, the jet flame injected from the communication passage 204a on the side where the protrusion 208a is located has strong penetration power. This reduces unburned hydrocarbons in the gap between the protrusion 208a and the cylinder 210a. Meanwhile, a jet flame with weaker penetration power is injected from the other communication passage 204b. This suppresses the collision of the jet flame with the cylinder. As a result, this pre-chamber internal combustion engine 201 can reduce cooling loss.

[0035] Third Embodiment Next, a third embodiment will be described with reference to Fig. 5. In the third embodiment, only the differences from the first embodiment will be described.

[0036] 5, in an auxiliary combustion chamber type internal combustion engine 301 according to the third embodiment, of the multiple communication passages 304 provided in an auxiliary combustion chamber 303, the longer the communication passage 304 is in the direction of the distance D301 from the center line C302 of the auxiliary combustion chamber 303 to the cylinder 310a, the longer the length of the communication passage 304. The piston 308 is a flat piston without a protrusion 308a. The other configurations of the third embodiment are the same as those of the first embodiment.

[0037] In this pre-chamber internal combustion engine 301, the farther the communicating passage 304 is from the cylinder 310a, the stronger the penetration force of the jet flame injected from the communicating passage 304. This promotes combustion by the jet flame with stronger penetration force, and reduces unburned hydrocarbons. Also, the closer the communicating passage 304 is in the direction of the distance D301, the more the jet flame is suppressed from impinging on the cylinder. As a result, this pre-chamber internal combustion engine 301 can reduce cooling loss.

[0038] As described above, according to the present disclosure, it is possible to provide a pre-chamber internal combustion engine 1, 201, 301 that can reduce unburned hydrocarbons while suppressing cooling loss.

[0039] <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.

[0040] (a) Regarding the length L1 of the first communication passage 4a in the first embodiment, as in the third embodiment, the length L1 of the first communication passage 4a may be longer as the distance from the center line C2 of the auxiliary combustion chamber 3 to the cylinder 10a increases.

[0041] (b) Furthermore, in the second and third embodiments, a communication passage facing the piston side (the third communication passage 4c in the first embodiment) is not disclosed, but the second and third embodiments may also be provided with a third communication passage 4c, as in the first embodiment. In this case, the length of the third communication passage 4c may be shorter than the length of each communication passage.

[0042] (c) Furthermore, in the first and second embodiments, the protrusions 8a are provided on the intake and exhaust sides around the top surface of the piston 8, but the present disclosure is not limited to this. As shown in Fig. 6, the protrusions 8a may be provided in the longitudinal direction of the internal combustion engine (the direction in which the crankshaft extends). In this case, the length L1 of the first communication passage 4a on the side where the protrusions 8a are located may be longer than the length L2 of the second communication passage. [Explanation of symbols]

[0043] 1, 201, 301: Pre-chamber internal combustion engine 3,203,303: Pre-combustion chamber 4: Communication path, 4a: First communication path, 4b: Second communication path, 4c: Third communication path 5: Pre-combustion chamber wall, 6: Ignition device 8,208,308: Piston 8a,208a,308a: Protrusion 9: Fuel injection valve 10a, 210a, 310a: Cylinder

Claims

1. A main combustion chamber; an auxiliary combustion chamber disposed between the main combustion chamber and the auxiliary combustion chamber via a partition wall; a communication passage disposed in the partition wall; Equipped with The communication passage is a first communication passage disposed on a lean side of the main combustion chamber where the air-fuel mixture becomes lean; a second communication passage disposed on a rich side of the main combustion chamber where the air-fuel mixture becomes rich; and The length of the first communication passage is longer than the length of the second communication passage. Pre-chamber internal combustion engine.

2. Further provided is a fuel injection valve for injecting fuel, The first communication passage is disposed on the side where the fuel injection valve is disposed.

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

3. a cylinder surrounding the main combustion chamber; Further comprising a piston that slides within the cylinder, the communication passage includes a third communication passage directed toward the piston, the third communication passage is shorter than the first communication passage and the second communication passage; 3. The pre-chamber internal combustion engine according to claim 1 or 2.

4. A main combustion chamber; an auxiliary combustion chamber disposed between the main combustion chamber and the auxiliary combustion chamber via a partition wall; a communication passage disposed in the partition wall; a piston that slides within a cylinder that surrounds the main combustion chamber; Equipped with There are a plurality of communication paths, Among the plurality of communication passages, a communication passage on a side where a protrusion is arranged on the top surface of the piston is set to have a longer distance than a communication passage on a side where no protrusion is arranged. Pre-chamber internal combustion engine.

5. A main combustion chamber; an auxiliary combustion chamber disposed between the main combustion chamber and the auxiliary combustion chamber via a partition wall; a communication passage disposed in the partition wall; a cylinder surrounding the main combustion chamber; Equipped with There are a plurality of communication paths, Among the plurality of communication passages, the farther the communication passage is from the cylinder, the longer the distance of the communication passage. Pre-chamber internal combustion engine.

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