WO2020196208A1

WO2020196208A1 - Auxiliary chamber-type internal combustion engine

Info

Publication number: WO2020196208A1
Application number: PCT/JP2020/012158
Authority: WO
Inventors: 晃弘津田; 田中　大; 貴之城田; 欣也井上; 佳博菅田; 一成野中; 遼太朝倉; 捷飯塚
Original assignee: 三菱自動車工業株式会社
Priority date: 2019-03-27
Filing date: 2020-03-18
Publication date: 2020-10-01
Also published as: JP2022081705A

Abstract

This auxiliary chamber-type internal combustion engine is provided with a main chamber, an auxiliary chamber, a communication channel, and an ignition part. The main chamber is defined by a cylinder head, a cylinder, and a piston. The auxiliary chamber protrudes from the cylinder head toward the main chamber, and is separated from the main chamber by a partition wall. The communication channel penetrates the partition wall inside out so as to connect the main chamber and the auxiliary chamber. The ignition part is disposed inside the auxiliary chamber, and ignites an air-fuel mixture that is introduced into the auxiliary chamber from the main chamber via the communication channel. The partition wall has a protruding section that protrudes toward the ignition part. The protruding section includes a sloping surface formed in a truncated conical shape, the diameter of which becomes increasingly smaller toward the ignition part.

Description

Sub-chamber internal combustion engine

The present disclosure relates to a sub-chamber type internal combustion engine having a main chamber and a sub-chamber provided adjacent to the main chamber.

Conventionally, a sub-chamber type internal combustion engine having a main chamber (main combustion chamber) and a sub-chamber (sub-combustion chamber) provided adjacent to the main chamber has been proposed (for example, Japanese Patent Application Laid-Open No. 2006-144648). See Gazette). In such a sub-chamber internal combustion engine, an air-fuel mixture is formed from the fuel injected into the main chamber. The formed air-fuel mixture is supplied to the sub-chamber via the communication passage, and is ignited by the spark plug in the sub-chamber. As a result, a flame is formed. The flame formed in the sub-chamber is jetted into the main chamber through the continuous passage and ignites the air-fuel mixture in the main chamber. By injecting the flame formed in the sub chamber into the main chamber in this way, the combustion speed of the main chamber is increased. This enables operation with a leaner air-fuel ratio and improves fuel efficiency.

Further, in the sub-chamber internal combustion engine described in Japanese Patent Application Laid-Open No. 2006-144648, a plate-shaped barrier is provided on the inner wall surrounding the spark plug in the sub-chamber, whereby the swirling flow of the air-fuel mixture is attenuated. Attenuation of the swirling flow guides the air-fuel mixture near the spark plug, resulting in an increase in the lean limit.

However, in the sub-chamber internal combustion engine described in Japanese Patent Application Laid-Open No. 2006-144648, the swirling flow of the air-fuel mixture in the sub-chamber is easily disturbed. Therefore, it cannot be said that the air-fuel mixture reaches the spark plug in a stable manner, and the lean limit is not sufficiently expanded.

The embodiment of the present invention relates to a sub-chamber internal combustion engine having a sufficiently expanded lean limit.

According to the first embodiment of the present invention, the sub-chamber internal combustion engine includes a main chamber, a sub-chamber, a communication passage, and an ignition unit. The main chamber is defined by a cylinder head, a cylinder, and a piston. The sub-chamber projects from the cylinder head toward the main chamber and is separated from the main chamber by a partition wall. The communication passage penetrates the partition wall inside and outside to communicate the main room and the sub room. The ignition unit is provided in the sub-chamber and ignites the air-fuel mixture introduced from the main room to the sub-chamber via the communication passage. The partition wall has a convex portion that protrudes toward the ignition portion, and the convex portion includes a frustum-shaped inclined surface whose diameter decreases toward the ignition portion.

This sub-chamber type internal combustion engine has a convex portion protruding from the partition wall toward the ignition portion, and the convex portion includes a frustum-shaped inclined surface whose diameter decreases toward the ignition portion. As a result, the air-fuel mixture introduced from the main chamber to the sub-chamber via the communication passage is guided to the ignition portion along the inclined surface. Therefore, the air-fuel mixture reaches the vicinity of the ignition portion in a stable manner, and the lean limit is sufficiently expanded.

The degree of inclination of the inclined surface of the convex portion may increase as it approaches the ignition portion.

The extension region when the continuous passage is extended to the sub-chamber along the penetrating direction of the side wall may reach the region of the inclined surface in the convex portion.

In these sub-chamber internal combustion engines, the degree of inclination of the inclined surface in the convex portion increases as it approaches the ignition portion. As a result, the angle difference between the introduction direction of the air-fuel mixture introduced from the main chamber to the sub chamber via the continuous passage and the inclined surface in the convex portion becomes small, and unnecessary turbulence is suppressed. Then, as the degree of inclination after that becomes large, this air-fuel mixture is surely guided to the ignition portion. Further, when the extension line of the continuous passage extending along the penetrating direction of the continuous passage reaches the region having the smallest degree of inclination in the convex portion, in the continuous passage of the jet flame ejected from the sub chamber to the main chamber. The contraction loss is suppressed. This enhances the penetration of the jet flame and promotes combustion in the main chamber.

The outer surface of the convex portion located on the main chamber side may be flat or convex toward the main chamber.

In this sub-chamber type internal combustion engine, the outer surface of the convex portion located on the main chamber side is provided in a flat shape or is provided in a convex shape toward the main chamber. Due to the structure of the sub-chamber internal combustion engine, the outer surface of the convex portion located on the main chamber side is less likely to be struck by the flame that is ignited by the ignition portion and injected from the communication passage. However, since the convex portion is provided as described above, there is no region where the flame is difficult to wrap around, and there is no loss due to unburned air-fuel mixture.

The ignition unit may be composed of a pair of electrodes. Then, one of the pair of electrodes of the electrode pair protrudes from the inner wall of the sub chamber, and the other electrode of the pair of electrodes is arranged at a position separated from the one electrode, and is a frustum of the convex portion. It may be attached to the apex region protruding in a shape.

In this sub-chamber internal combustion engine, since the other electrode in the electrode pair is attached to the convex portion, it is straight from the inner wall of the sub-chamber toward the convex portion without arranging a conduction path around each electrode. Each electrode is arranged on the line. As a result, the flame spreads properly.

Schematic diagram showing a schematic configuration of a sub-chamber internal combustion engine according to an embodiment of the present disclosure. Enlarged view (1/4) showing the vicinity of the sub chamber of the sub chamber type internal combustion engine of FIG. Enlarged view (2/4) showing the vicinity of the sub-chamber of the sub-chamber type internal combustion engine of FIG. Enlarged view (3/4) showing the vicinity of the sub-chamber of the sub-chamber type internal combustion engine of FIG. Enlarged view (4/4) showing the vicinity of the sub-chamber of the sub-chamber type internal combustion engine of FIG.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

(1) Overall Configuration As shown in FIG. 1, the sub-chamber internal combustion engine 1 has a main chamber 10 including a structure surrounding a combustion space 100 extending in a tubular shape, and a sub-chamber extending in a tubular shape toward the combustion space 100. 20 and an ignition plug 30 protruding from the inner wall of the sub chamber 20 are provided. The sub-chamber internal combustion engine 1 repeats intake, compression, expansion, and exhaust strokes.

The main chamber 10 has a cylinder 11 extending in a predetermined direction (vertical direction in FIG. 1), a cylinder head 13 that closes one end (upper end of the cylinder 11 in FIG. 1) side of the cylinder 11, and a direction extending inside the cylinder 11. Includes a piston 15 that reciprocates along. The combustion space 100 is defined by the cylinder 11, the cylinder head 13, and the piston 15. The intake port 120 opened and closed by the intake valve 110 and the exhaust port 140 opened and closed by the exhaust valve 130 are connected to the combustion space 100, respectively. The intake valve 110 and the exhaust valve 130 are driven by an intake cam and an exhaust cam (not shown).

Further, in the main chamber 10, an injection valve 150 for injecting fuel into the combustion space 100 is arranged in the vicinity of the intake port 120 in the cylinder 11. The injection valve 150 sprays and supplies fuel. As a result, an air-fuel mixture is formed in the combustion space 100.

The main chamber 10 in the present embodiment has a pent roof shape, and the cylinder head 13 has two slopes inclined toward the intake port 120 and the exhaust port 140, respectively.

The sub chamber 20 is separated from the main chamber 10 by a partition wall, and the partition wall includes the side wall 21 and the end wall 23. As shown in FIG. 2, the side wall 21 projects from the cylinder head 13 toward the combustion space 100 and extends in a tubular shape. The end wall 23 closes the tip of the side wall 21 (the lower end of the side wall 21 in FIG. 1). That is, the sub chamber 20 is defined by the side wall 21 and the end wall 23. In the present embodiment, the sub chamber 20 is provided at a position straddling the intersection (ridge line) of two pent roof-shaped slopes in the main chamber 10.

Further, the sub chamber 20 includes one or more connected passages 40 that penetrate the side wall 21 in and out and communicate the sub chamber 20 and the main chamber 10, and a convex portion of the end wall 23 that protrudes from the sub chamber 20 side. With 50. The convex portion 50 includes a truncated cone-shaped (conical truncated cone shape in the present embodiment) inclined surface whose diameter becomes smaller toward the electrode pair (

electrodes

31 and 33 described later) of the spark plug 30.

The inclination angle of the frustum-shaped inclined surface with respect to the plane orthogonal to the protruding direction of the sub chamber 20 increases as it approaches the electrode pair, in other words, the inclination degree of the inclined surface increases as it approaches the electrode pair. In addition, the convex portion 50 may be formed. Specifically, as shown in FIG. 3, the closer to the electrode pair, the greater the inclination angle of the frustum-shaped inclined surface with respect to the plane orthogonal to the protruding direction of the sub chamber 20 stepwise (two steps in FIG. 3). As such, the convex portion 50 may be formed. Further, the convex portion 50 may be formed so that the inclination angle is continuously increased.

Further, the connecting passages 40 are provided at one or more places on the side wall 21, and perform intake air from the main room 10 to the sub room 20 or scavenging from the sub room 20 to the main room 10. Further, the extension region when the communication passage 40 is extended into the sub chamber 20 along the penetrating direction of the side wall 21 reaches the inclined surface of the convex portion 50.

Here, when the inclination angle of the frustum-shaped inclined surface of the convex portion 50 is formed to be large stepwise, as shown in FIG. 3, the extension region has the smallest degree of inclination in the convex portion 50. Reach the area. That is, the extension region of the communication passage 40 reaches the outermost circumference on the frustum-shaped inclined surface.

In the present embodiment, the communication passage 40 penetrates the side wall 21 portion located in the main chamber 10 inside and outside, but is embedded in the structure (specifically, the cylinder head 13) side of the main chamber 10. The side wall 21 portion may be penetrated inside and outside together with the structure of the main chamber 10 to communicate the sub chamber 20 and the main chamber 10.

Further, as shown in FIG. 4, the main chamber 10 side of the end wall 23 may be provided in a plane shape that intersects the protruding direction of the sub chamber 20, and a plane that intersects the protruding direction of the sub chamber 20. It may be provided in a convex shape toward the main room 10. At this time, the main chamber 10 side of the end wall 23 and the sub chamber 20 side of the convex portion 50 are formed of the same member, and there does not have to be a space between them. Further, the main chamber 10 side of the end wall 23 and the sub chamber 20 side of the convex portion 50 are formed of different plate-shaped members, and a space may exist between them.

The spark plug 30 is provided with a pair of electrodes, and the pair of electrodes is arranged at a position protruding from the inner wall on the end (upper end in FIG. 1) side in the sub chamber 20. The electrode pair includes a pair of

electrodes

31 and 33, and the spark plug 30 ignites the air-fuel mixture in the sub chamber 20 by energizing between the pair of

electrodes

31 and 33.

The pair of

electrodes

31 and 33 are arranged at intervals on a straight line extending from the inner wall of the sub chamber 20 toward the convex portion 50. Of the pair of

electrodes

31 and 33, one electrode 31 is connected to a conduction path (not shown) provided at a position overlapping the axis of the spark plug 30, and the other electrode 33 is connected to the conduction path 35. There is. The conduction path 35 has a first path extending along the axis of the spark plug 30 from a position separated from one of the electrodes 31, and a second path extending in the direction from the tip end side of the first path toward the axis of the spark plug 30. Including the route of.

Here, as shown in FIG. 5, a part or the whole of the convex portion 50 is a conduction path 37, and the other electrode 33 is connected to the apex region protruding like a frustum in the convex portion 50. May be done.

In the sub-chamber internal combustion engine 1 configured in this way, the volume of the sub-chamber 20 is smaller than that of the main chamber 10, and the flame of the air-fuel mixture ignited by the spark plug 30 quickly propagates into the sub-chamber 20. The sub chamber 20 injects the flame generated in the sub chamber 20 into the main chamber 10 via the communication passage 40. The flame injected into the main chamber 10 ignites and burns the air-fuel mixture in the main chamber 10. In this way, the main chamber 10 and the sub chamber 20 form an integrated combustion chamber.

(2) Action and effect In the above-mentioned sub-chamber internal combustion engine 1, the convex portion 50 projects from the end wall 23 toward the electrode pair of the spark plug 30, and the convex portion 50 has a diameter toward the electrode pair. It has a small frustum-shaped inclined surface. As a result, the air-fuel mixture introduced from the main chamber 10 to the sub chamber 20 via the communication passage 40 is guided to the electrode pair along the inclined surface (see the broken line arrows in FIGS. 2 to 5). Therefore, the air-fuel mixture stably reaches the vicinity of the

electrodes

31 and 33, and the lean limit is sufficiently expanded.

Further, in the sub-chamber type internal combustion engine 1, when the degree of inclination of the inclined surface in the convex portion 50 increases as it approaches the electrode pair, it is introduced from the main chamber 10 to the sub-chamber 20 via the communication passage 40. The angle difference between the introduction direction of the air-fuel mixture and the inclined surface of the convex portion 50 is reduced, and unnecessary turbulence is suppressed. Then, as the degree of inclination after that becomes large, this air-fuel mixture is surely guided to the electrode pair. Further, when the extension line of the communication passage 40 extending along the penetrating direction of the communication passage 40 comes into line contact with the region having the smallest inclination degree in the convex portion 50 (FIGS. 4 and 5), the sub chamber 20 to the main chamber Since the contraction loss in the communication passage 40 of the jet flame ejected to 10 is suppressed, the penetration force of the jet flame is strengthened and the combustion in the main chamber 10 is promoted.

Further, in the above embodiment, when the main chamber 10 side of the end wall 23 is provided in a plane shape intersecting the protruding direction of the sub chamber 20, or is provided in a convex shape toward the main chamber 10, as follows. The effect is produced. That is, due to the structure of the sub-chamber internal combustion engine 1 at the end of the sub-chamber 20 on the main chamber 10 side, it is difficult for the flame injected from the communication passage 40 to ignite the electrode pair to wrap around. However, since the end wall 23 is provided as described above, there is no region where the flame is difficult to wrap around, and there is no loss due to unburned air-fuel mixture.

Further, in the sub-chamber type internal combustion engine 1, when the other electrode 33 in the electrode pair is attached to the convex portion 50, the sub-chamber 20 is not arranged around the conduction paths 35 around the

electrodes

31 and 33. The

electrodes

31 and 33 are arranged in a straight line from the inner wall of the surface toward the convex portion 50. Therefore, the flame spreads appropriately.

(3) 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 can be made without departing from the gist of the invention. In particular, the configurations described herein can be arbitrarily combined as needed.

For example, in the above embodiment, the convex portion 50 has an inclined surface extending in a truncated cone shape, and the convex portion 50 projects so as to have a smaller diameter from the sub-chamber side of the end wall toward the electrode pair. It may be in the shape of a truncated cone, and may be in the shape of a truncated cone.

Further, in the above embodiment, the convex portion 50 has an inclined surface extending in a truncated cone shape, but even if a spiral groove or protrusion from the bottom of the truncated cone to the apex region is formed along the inclined surface. Good.

According to the embodiment of the present disclosure, the sub-chamber internal combustion engine (1) is
A main chamber (10) defined by a cylinder head (13), a cylinder (11), and a piston (15),
A sub-chamber (20) protruding from the cylinder head (13) toward the main chamber (10) and separated from the main chamber (10) by a partition wall (21, 23).
A communication passage (40) that penetrates the partition wall (21) in and out and communicates the main chamber (10) and the sub chamber (20).
An ignition unit (30) provided in the sub chamber (20) and igniting an air-fuel mixture introduced from the main chamber (10) to the sub chamber (20) via the communication passage (40).
With
The partition wall (23) has a convex portion (50) protruding toward the ignition portion (30).
The convex portion (50) includes a frustum-shaped inclined surface whose diameter decreases toward the ignition portion (30).

The degree of inclination of the inclined surface may increase as it approaches the ignition portion (30).

The extension region when the communication passage (40) is extended into the sub chamber (20) along the penetrating direction of the partition wall (21) may reach the region of the inclined surface.

The degree of inclination of the inclined surface may gradually increase as it approaches the ignition portion (30). Then, the extension region may reach the region having the smallest degree of inclination on the inclined surface.

The outer surface of the convex portion (50) located on the main chamber (10) side may be flat or convex toward the main chamber (10).

The ignition unit (30) may be composed of a pair of electrodes. Then, one of the pair of electrodes (31, 33) of the pair of electrodes protrudes from the inner wall of the sub chamber (20), and the other electrode of the pair of electrodes (31, 33) is the one. It is arranged at a position separated from the electrode of the above, and may be attached to the apex region of the convex portion (50) protruding like a frustum.

This application is based on Japanese Patent Application No. 2019-061128 filed on March 27, 2019, the contents of which are incorporated herein by reference.

1 Sub-chamber internal combustion engine 10 Main chamber 11 Cylinder 13 Cylinder head 15 Piston 20 Sub-chamber 21 Side wall 23 End wall 30 Spark plug 31 Electrode 33 Electrode 35 Conduction path 37 Conduction path 40 Continuity path 50 Convex part 100 Combustion space 110 Intake Valve 120 Intake port 130 Exhaust valve 140 Exhaust port 150 Injection valve

Claims

A main chamber defined by a cylinder head, a cylinder, and a piston,
A sub chamber that protrudes from the cylinder head toward the main chamber and is separated from the main chamber by a partition wall.
A communication passage that penetrates the partition wall in and out and connects the main chamber and the sub chamber,
An ignition unit provided in the sub-chamber and igniting an air-fuel mixture introduced into the sub-chamber from the main chamber via the communication passage.
With
The partition wall has a convex portion projecting toward the ignition portion and has a convex portion.
The convex portion is a sub-chamber type internal combustion engine including a frustum-shaped inclined surface whose diameter becomes smaller toward the ignition portion.
The degree of inclination of the inclined surface increases as it approaches the ignition portion.
The sub-chamber internal combustion engine according to claim 1.
The extension region when the communication passage is extended to the sub chamber along the penetrating direction of the partition wall reaches the region of the inclined surface.
The sub-chamber internal combustion engine according to claim 1 or 2.
The degree of inclination of the inclined surface gradually increases as it approaches the ignition portion.
The extension region reaches the region having the smallest degree of inclination on the inclined surface.
The sub-chamber internal combustion engine according to claim 3.
The outer surface of the convex portion located on the main chamber side is flat or convex toward the main chamber.
The sub-chamber internal combustion engine according to any one of claims 1 to 4.
The ignition unit is composed of a pair of electrodes.
One of the pair of electrodes of the pair of electrodes projects from the inner wall of the sub-chamber.
The other electrode of the pair of electrodes is arranged at a position separated from the one electrode, and is attached to the apex region of the convex portion protruding like a frustum.
The sub-chamber internal combustion engine according to any one of claims 1 to 5.