Auxiliary chamber type internal combustion engine

Abstract

To provide an auxiliary chamber type internal combustion engine capable of suppressing shock caused by a jet flame.SOLUTION: An auxiliary chamber type internal combustion engine includes an ignition device, a main combustion chamber, and an auxiliary combustion chamber disposed to separate from the main combustion chamber via an inner wall. The auxiliary combustion chamber includes a first auxiliary combustion chamber and a second auxiliary combustion chamber disposed to separate from the first auxiliary combustion chamber via a wall. The ignition device is disposed in the first auxiliary combustion chamber, and the inner wall includes a communication passage that communicates the first auxiliary combustion chamber and the second auxiliary combustion chamber.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a prechamber internal combustion engine.

Background Art

[0002] Conventionally, a prechamber internal combustion engine has been known (see, for example, Patent Document 1). The prechamber internal combustion engine includes a main combustion chamber and a prechamber, and ignites the air-fuel mixture in the main combustion chamber by injecting a jet flame from the prechamber toward the main combustion chamber. In such a prechamber internal combustion engine, the column vibration generated by the flame propagation in the main combustion chamber may be amplified by the column vibration generated by the jet flame injected from the prechamber, generating a shock. Such a shock may also be referred to as a jet shock.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The air-fuel mixture in the main combustion chamber may have a difference in concentration due to the flow in the main combustion chamber. When a difference in concentration occurs in the main combustion chamber, a difference in the flame propagation speed in the main combustion chamber occurs according to the difference in concentration. When variation occurs in the jet flame injected from the prechamber, the difference in the flame propagation speed in the main combustion chamber is more likely to increase. When the difference in the flame propagation speed increases, the shock is more likely to increase.

[0005] An object of the present disclosure is to provide a prechamber internal combustion engine capable of suppressing the shock caused by the jet flame.

Means for Solving the Problems

[0006] The auxiliary chamber type internal combustion engine according to the present disclosure includes an ignition device, a main combustion chamber, and an auxiliary combustion chamber disposed separately from the main combustion chamber via an inner wall. The auxiliary combustion chamber has a first auxiliary combustion chamber and a second auxiliary combustion chamber disposed separately from the first auxiliary combustion chamber via a wall. The ignition device is disposed in the first auxiliary combustion chamber, and a communication passage communicating the first auxiliary combustion chamber and the second auxiliary combustion chamber is provided in the inner wall.

Advantages of the Invention

[0007] According to this configuration, the air-fuel mixture in the first auxiliary combustion chamber where the ignition device is disposed first is ignited, and a jet flame is injected from the first auxiliary combustion chamber into the main combustion chamber. The jet flame in the first auxiliary combustion chamber is injected into the second auxiliary combustion chamber through the communication passage provided in the inner wall to ignite the air-fuel mixture in the second auxiliary combustion chamber, and a jet flame is injected from the second auxiliary combustion chamber toward the main combustion chamber with a delay from the jet flame in the first auxiliary combustion chamber. That is, an intentional phase difference can be provided between the jet flame injected from the first auxiliary combustion chamber and the jet flame injected from the second auxiliary combustion chamber. Thereby, for example, by arranging the first auxiliary combustion chamber and the second auxiliary combustion chamber according to the air-fuel ratio of the air-fuel mixture in the main combustion chamber, the difference in flame propagation speed in the main combustion chamber can be reduced. As a result, the shock caused by the jet flame can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

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

[0010] As shown in FIG. 1, the auxiliary 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 the present embodiment, the main combustion chamber 2 has a pentroof shape in which two slopes are 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 to, for example, 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 to, for example, an exhaust passage (not shown).

[0012] The auxiliary combustion chamber 4 is disposed adjacent to the main combustion chamber 2 at the top of the pentroof shape and has a space surrounded by an auxiliary combustion chamber wall 4a. The auxiliary combustion chamber 4 protrudes from the cylinder head 12 toward the main combustion chamber 2 and is disposed at a distance from the main combustion chamber 2 via the auxiliary combustion chamber wall 4a. The auxiliary combustion chamber wall 4a has a side wall 41, a bottom wall 42, and an upper wall 43. The side wall 41 is a wall that separates the cylinder 10a side of the auxiliary combustion chamber 4 from the main combustion chamber 2. The bottom wall 42 is a wall that separates the piston 8 side of the auxiliary combustion chamber 4 from the main combustion chamber 2. In the present embodiment, the bottom wall 42 is formed in an arc shape or a straight line shape in cross section. However, the shape of the bottom wall 42 is not limited to this, and any shape may be used. The upper wall 43 is a wall that separates the auxiliary combustion chamber 4 from the cylinder head 12. The upper wall 43 may be formed integrally with the cylinder head 12.

[0013] As shown in Fig. 2(a), the secondary combustion chamber 4 has a first secondary combustion chamber 4b, a second secondary combustion chamber 4c, and an inner wall 4d. The second secondary combustion chamber 4c is disposed at a distance from the first secondary combustion chamber 4b with the inner wall 4d in between. The inner wall 4d has a secondary combustion chamber internal communication passage (an example of a communication passage) 4h that communicates the first secondary combustion chamber 4b and the second secondary combustion chamber 4c. In the present embodiment, the secondary combustion chamber internal communication passage 4h is disposed between the upper end 4e of the inner wall 4d and the upper wall 43. However, the secondary combustion chamber internal communication passage 4h may be, for example, extended to the upper wall 43 along the inner wall 4d and disposed in the middle of the inner wall 4d. When the secondary combustion chamber internal communication passage 4h is disposed in this way, a gas pocket is formed above the secondary combustion chamber internal communication passage 4h in the second secondary combustion chamber 4c. The gas pocket holds the un-scavenged pre-cycle burned gas and promotes the induction of the air-fuel mixture to the vicinity of the spark plug.

[0014] As shown in Figs. 2(a) and 2(b), in the present embodiment, the first secondary combustion chamber 4b is disposed on the intake side, and the second secondary combustion chamber 4c is disposed on the exhaust side. The volume of the second secondary combustion chamber 4c is larger than the volume of the first secondary combustion chamber 4b. As shown in Fig. 2(b), in the present embodiment, the first secondary combustion chamber 4b has a side wall 41 on the intake side formed in a semi-circular cross-section or an arcuate cross-section. The second secondary combustion chamber 4c has a side wall 41 on the exhaust side formed in an arcuate cross-section. However, the cross-sectional shapes of the first secondary combustion chamber 4b and the second secondary combustion chamber 4c may be changed as appropriate.

[0015] As shown in Figs. 2(a) and 2(b), the first communication passage 4f is disposed in the first secondary combustion chamber 4b and communicates with the intake side of the main combustion chamber 2. In the present embodiment, three first communication passages 4f directed in different directions are disposed on the side wall 41 of the first secondary combustion chamber 4b. However, the number of the first communication passages 4f may be changed as appropriate.

[0016] The second communication passage 4g is disposed in the second secondary combustion chamber 4c and communicates with the exhaust side of the main combustion chamber 2. In the present embodiment, three second communication passages 4g directed in different directions are disposed on the side wall 41 of the second secondary combustion chamber 4c. However, the number of the second communication passages 4g may be changed as appropriate.

[0017] As shown in Fig. 2(a), the ignition device 6 is arranged in the first sub-combustion chamber 4b. The ignition device 6 has an ignition coil (not shown) and an ignition plug 6a. The center electrode 6b and the side electrode 6c of the ignition plug 6a project into the first sub-combustion chamber 4b. In this embodiment, the center electrode 6b is arranged at approximately the center of the first sub-combustion chamber 4b. However, the center electrode 6b may be arranged offset from approximately the center of the first sub-combustion chamber 4b.

[0018] As shown in Fig. 1, the piston 8 is accommodated in the cylinder 10a and slides within the cylinder 10a. The piston 8 surrounds the main combustion chamber 2 from below. The fuel injection valve 9 injects fuel toward the main combustion chamber 2 and the sub-combustion chamber 4, and forms an air-fuel mixture of air and fuel in the main combustion chamber 2 and the sub-combustion chamber 4. In this embodiment, the fuel injection valve 9 is a direct injection type that injects fuel directly into the cylinder 10a. However, the fuel injection valve 9 may be of a port injection type.

[0019] As shown in Fig. 3(a), in the sub-chamber type internal combustion engine 1 configured as described above, fuel is injected by the fuel injection valve 9 to form an air-fuel mixture in the main combustion chamber 2 and the sub-combustion chamber 4. At this time, the fuel is injected toward the exhaust side, and the air-fuel ratio of the air-fuel mixture on the exhaust side tends to become rich due to the in-cylinder flow.

[0020] As shown in Fig. 3(b), when the ignition device 6 ignites the ignition plug 6a, first, the air-fuel mixture in the first sub-combustion chamber 4b ignites, and a jet flame is injected from the first communication passage 4f. Further, the flame in the first sub-combustion chamber 4b injects a jet flame into the second sub-combustion chamber 4c through the sub-combustion chamber internal communication passage 4h.

[0021] As shown in Fig. 3(c), when the air-fuel mixture in the second sub-combustion chamber 4c ignites, a flame is injected from the second communication passage 4g.

[0022] In this way, in the auxiliary chamber type internal combustion engine 1, the jet flame injected from the second auxiliary combustion chamber 4c is injected with a phase delay with respect to the jet flame injected from the first auxiliary combustion chamber 4b. In the present embodiment, since the air-fuel ratio on the intake side is lean, the flame propagation speed is slower on the intake side than on the exhaust side. However, in this auxiliary chamber type internal combustion engine 1, the air-fuel mixture on the intake side receives the jet flame for a longer time than the air-fuel mixture on the exhaust side, so that the flame propagation speed on the intake side is promoted. On the other hand, since the air-fuel ratio on the exhaust side is rich, the flame propagation speed is suppressed by receiving the jet flame later than on the intake side. Thereby, the difference in the flame propagation speed between the intake side and the exhaust side can be reduced. As a result, the shock caused by the jet flame is suppressed.

[0023] Furthermore, in the present embodiment, the volume of the second auxiliary combustion chamber 4c is smaller than the volume of the first auxiliary combustion chamber 4b. For this reason, the flame propagation speed in the second auxiliary combustion chamber 4c is slower than that in the first auxiliary combustion chamber 4b. Thereby, the momentum of the jet flame injected from the second communication passage 4g is weaker than that from the first communication passage 4f. As a result, the flame propagation speed on the exhaust side can be further suppressed.

[0024] <Second Embodiment> Next, the second embodiment will be described. Only the differences from the first embodiment will be described in the second embodiment.

[0025] As shown in FIG. 4, the auxiliary chamber type internal combustion engine 201 includes a main combustion chamber 202, an auxiliary combustion chamber 204, an ignition device 206, a piston 208, and a fuel injection valve 209. Since the parts other than the auxiliary combustion chamber 204 are the same as those in the first embodiment, the description thereof will be omitted.

[0026] As shown in Fig. 5(a), the sub-combustion chamber 204 has a first sub-combustion chamber 204b and a second sub-combustion chamber 204c. The second sub-combustion chamber 204c is disposed at a distance from the first sub-combustion chamber 204b via an inner wall 204d. The inner wall 204d of the present embodiment is formed in an annular shape. Therefore, the second sub-combustion chamber 204c is formed to surround the first sub-combustion chamber 204b. A sub-combustion chamber internal communication passage (an example of a communication passage) 204i that communicates the first sub-combustion chamber 204b and the second sub-combustion chamber 204c is formed in an annular shape. In the present embodiment, the sub-combustion chamber internal communication passage 204i is located on the cylinder head 12 side rather than on the side electrode 206c of the ignition device 6. As a result, after the air-fuel mixture around the ignition device 206 in the first sub-combustion chamber 204b is ignited, the flame easily propagates to the sub-combustion chamber internal communication passage 204i.

[0027] As shown in Fig. 5(b), in the present embodiment, the first sub-combustion chamber 204b is formed with a circular cross-section. The second sub-combustion chamber 204c is formed with an elliptical cross-section. The center of the first sub-combustion chamber 204b is offset toward the intake side compared to the center of the second sub-combustion chamber 204c.

[0028] The first communication passage 204f is disposed in the second sub-combustion chamber 204c and communicates with the intake side of the main combustion chamber 2. In the present embodiment, three first communication passages 204f directed in different directions are disposed on the side wall 241 of the second sub-combustion chamber 204c.

[0029] The second communication passage 204g is disposed in the second sub-combustion chamber 204c and communicates with the exhaust side of the main combustion chamber 2. In the present embodiment, three second communication passages 204g directed in different directions are disposed on the side wall 241 of the second sub-combustion chamber 204c.

[0030] As shown in Figs. 5(a) and 5(b), the third communication passage 204h is disposed in the first sub-combustion chamber 204b and communicates with the piston 8 side (see Fig. 1) of the main combustion chamber 202. In the present embodiment, the third communication passage 204h is disposed on the bottom wall 242 of the first sub-combustion chamber 204b.

[0031] The auxiliary chamber type internal combustion engine 201 configured as described above injects fuel by the fuel injection valve 209 to form an air-fuel mixture in the main combustion chamber 202 and the auxiliary combustion chamber 204. At this time, the fuel is injected toward the exhaust side, and the air-fuel ratio of the air-fuel mixture on the exhaust side tends to become rich due to the in-cylinder flow. As shown in FIG. 6(a), when the ignition device 206 ignites the spark plug 206a, first, the air-fuel mixture in the first auxiliary combustion chamber 204b ignites, and a jet flame is injected from the third communication passage 204h. Further, the flame in the first auxiliary combustion chamber 204b injects a jet flame into the second auxiliary combustion chamber 204c through the auxiliary combustion chamber internal communication passage 204i.

[0032] As shown in FIG. 6(b), when the air-fuel mixture in the second auxiliary combustion chamber 204c ignites, first, a jet flame is injected from the first communication passage 204f on the intake side with a small volume. As shown in FIG. 6(c), thereafter, a jet flame is injected from the second communication passage 204g on the exhaust side.

[0033] In this way, in the auxiliary chamber type internal combustion engine 201, the jet flame injected from the second auxiliary combustion chamber 204c is injected with a phase delay with respect to the jet flame injected from the first auxiliary combustion chamber 204b. By injecting the jet flame in the order of the third communication passage 204h on the piston side, the first communication passage 204f on the intake side, and the second communication passage 204g on the exhaust side, the difference in the flame propagation speed in the main combustion chamber 202 can be suppressed.

[0034] As described above, according to the present disclosure, it is possible to provide an auxiliary chamber type internal combustion engine 1, 201 that can suppress the shock caused by the jet flame.

[0035] <Other Embodiments> Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from the gist of the invention. In particular, a plurality of modifications described in this specification can be arbitrarily combined as needed.

[0036] (a) In the above-described first embodiment, an example in which the auxiliary combustion chamber 4 is divided into two chambers, the first auxiliary combustion chamber 4b and the second auxiliary combustion chamber 4c, has been described. However, the present disclosure is not limited to this. For example, the second auxiliary combustion chamber 4c may be further divided into finer chambers.

[0037] (b) Further, in the above-described first embodiment, an internal combustion engine in which the second auxiliary combustion chamber 4c is arranged on the exhaust side has been described. However, the second auxiliary combustion chamber may be arranged on the side where the air-fuel ratio is rich. For example, if the intake side becomes rich depending on the location and injection direction of the fuel injection valve 209, the second auxiliary combustion chamber 4c may be arranged on the intake side.

[0038] (c) In the above-described second embodiment, an example in which the second auxiliary combustion chamber 204c is arranged around the entire periphery of the first auxiliary combustion chamber 204b has been described. However, the present disclosure is not limited to this. For example, a plurality of second auxiliary combustion chambers 204c may be arranged on a part of the periphery of the first auxiliary combustion chamber 204b. Alternatively, the second auxiliary combustion chamber 204c may be divided into a plurality of chambers.

Explanation of Reference Numerals

[0039] 1, 201: Sub-chamber type internal combustion engine 2,202: Main combustion chamber 4,204: Auxiliary combustion chamber 4a: Auxiliary combustion chamber wall 4b,204b: First auxiliary combustion chamber 4c,204c: Second auxiliary combustion chamber 4d,204d: Inner wall 4f,204f: First communication passage 4g,204g: Second communication passage 204h: Third communication passage 4h,204i: Auxiliary combustion chamber internal communication passage 6,206: Ignition device 6a,206a: Spark plug 8,208: Piston

Claims

1. An ignition device, a main combustion chamber, a sub-combustion chamber disposed at a distance from the main combustion chamber via a wall, comprising: the sub-combustion chamber includes a first sub-combustion chamber, a second sub-combustion chamber disposed at a distance from the first sub-combustion chamber via an inner wall, having: the ignition device is disposed in the first sub-combustion chamber, a communication passage communicating the first sub-combustion chamber and the second sub-combustion chamber is provided in the inner wall, a sub-chamber type internal combustion engine.

2. the sub-combustion chamber has a first communication passage communicating with the intake side of the main combustion chamber and a second communication passage communicating with the exhaust side of the main combustion chamber, the first communication passage is disposed in the first sub-combustion chamber, the second communication passage is disposed in the second sub-combustion chamber, the flame injected from the second communication passage is injected later than the flame injected from the first communication passage, the sub-chamber type internal combustion engine according to Claim 1.

3. further comprising a piston surrounding the main combustion chamber, the sub-combustion chamber has a first communication passage communicating with the intake side of the main combustion chamber, a second communication passage communicating with the exhaust side of the main combustion chamber, and a third communication passage communicating with the piston side of the main combustion chamber, the third communication passage is disposed in the first sub-combustion chamber, the flame is injected in the order of the third communication passage, the first communication passage, and the second communication passage, the sub-chamber type internal combustion engine according to Claim 2.

4. the first sub-combustion chamber is disposed on the intake side and the second sub-combustion chamber is disposed on the exhaust side, the sub-chamber type internal combustion engine according to Claim 1.

5. the second sub-combustion chamber is disposed around the first sub-combustion chamber, the sub-chamber type internal combustion engine according to Claim 1.

6. the volume of the second sub-combustion chamber is smaller than the volume of the first sub-combustion chamber, the sub-chamber type internal combustion engine according to any one of Claims 1 to 5.

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