WO2021161554A1

WO2021161554A1 - Auxiliary chamber-type engine

Info

Publication number: WO2021161554A1
Application number: PCT/JP2020/025901
Authority: WO
Inventors: 浜程; 晃弘津田; 欣也井上
Original assignee: 三菱自動車工業株式会社
Priority date: 2020-02-10
Filing date: 2020-07-01
Publication date: 2021-08-19

Abstract

This auxiliary chamber-type engine comprises: a main chamber (21); an auxiliary chamber (22) partitioned from the main chamber (21) by a separation wall (23); and a plurality of communication paths (24) provided to the separation wall (23), wherein flame that is formed inside the auxiliary chamber (22) by the ignition of a mixed gas inside the auxiliary chamber (22) is jetted inside the main chamber (21) via the communication paths (24) and ignites a mixed gas inside the main chamber (21). The engine is provided with, on a main chamber (21) side of the separation wall (23), a protruding section (40) protruding to the main chamber (21) side, and the communication paths (24) are provided to the protruding section (40).

Description

Sub-chamber engine

The present invention relates to a sub-chamber engine provided with a system for igniting the air-fuel mixture in the main chamber by ejecting a flame formed by igniting the air-fuel mixture in the sub-chamber into the main chamber.

In the engine, an auxiliary combustion chamber (also referred to as a sub chamber) separated from the main combustion chamber (also referred to as a main chamber) by a partition is provided, and a communication passage connecting these main chamber and the sub chamber to each other is formed in the partition. It is equipped with a system (also called a jet ignition system) that ignites the air-fuel mixture in the sub-chamber so that the flame formed in the sub-chamber at this time is ejected into the main room through the communication passage to ignite the air-fuel mixture in the main room. In addition, a sub-chamber engine is known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2004-204835

By the way, in a sub-chamber engine equipped with a jet ignition system as described above, jet ignition can promote leaning of the air-fuel mixture, suppress the generation of NOx due to combustion in the main chamber, and improve fuel efficiency. It becomes possible to make it. However, if leaning is further promoted, combustion will slow down even with jet ignition. In order to further improve the thermal efficiency, it is an issue to make it possible to further promote combustion in the main chamber.

This case was created by paying attention to such issues, and one of the purposes is to make it possible to improve the thermal efficiency of a sub-chamber engine equipped with a jet ignition system. Not limited to this purpose, it is also an action and effect derived by each configuration shown in the embodiment for carrying out the invention described later, and it is also for another purpose of this case to exert an action and effect that cannot be obtained by the conventional technique. be.

The sub-chamber engine of the present invention includes a main chamber, a sub-chamber partitioned by the main chamber and a partition wall, and a plurality of passages provided in the partition wall and communicating the main chamber and the sub-chamber. A sub-chamber engine that ignites the air-fuel mixture in the main chamber by ejecting a flame formed in the sub-chamber by igniting the air-fuel mixture in the sub-chamber into the main chamber through the communication passage. A surface of the partition wall on the main chamber side is provided with a protrusion protruding toward the main chamber, and the protrusion is provided with the communication passage.

It is preferable that the communication passage provided in the protrusion is bent in the protrusion.
It is preferable that the communication passage includes a branch communication passage that is branched in a plurality of directions in the direction in which the flame is ejected.
The branch passage is branched into two, a side in the first direction along the axial direction of the cylinder in which the main chamber and the sub chamber are formed, and a side in the second direction opposite to the first direction. It is preferable that the axial dichotomized passage is included.
It is preferable that the communication passage includes a bending communication passage that is bent without branching in the direction in which the flame is ejected.
It is preferable that at least two of the passages are oriented so that the ejected flames collide with each other.
It is preferable that the flow path cross-sectional area S2 on the outlet side in the direction in which the flame is ejected from the communication passage is set to be equal to or less than the flow path cross-sectional area S1 on the inlet side in the direction in which the flame is ejected.
The communication passage includes a bending communication passage that is bent without branching in the direction in which the flame is ejected, and the outlet side of the plurality of bending communication passages from which the flame is ejected is from the clothing room to the main chamber. It is preferable that all of them are oriented in the same direction as the radial direction toward.
A fuel injection valve that injects fuel into the main chamber and a fuel inflow communication passage that is a part of the plurality of passages and introduces fuel injected from the fuel injection valve into the sub-chamber. It is preferable that at least two of the protrusions are arranged at positions sandwiching the opening of the fuel inflow communication passage.
It is preferable that a recess having a receiving surface on which the direct injection fuel from the fuel injection valve collides is formed around the opening of the fuel inflow communication passage.

According to this case, it is possible to increase the degree of freedom in the direction in which the flame formed in the sub-chamber is ejected into the main chamber and the position in which the flame is supplied to the main chamber.

1A to 1C are views showing the configuration of a combustion chamber of one cylinder of the sub-chamber engine according to the first embodiment, FIG. 1A is a vertical sectional view thereof, FIG. 1B is a top view thereof, and FIG. 1C is a top view thereof. It is a vertical cross-sectional view which shows the partition wall enlarged. 2A and 2B are views showing the second configuration of the partition wall shown in FIGS. 1A to 1C, FIG. 2A is a side view thereof, and FIG. 2B is a bottom view (viewed from below) thereof. FIG. 3 is a schematic plan view of the partition wall showing the orientation state of the communication passages formed in the partition wall shown in FIGS. 2A and 2B. FIG. 4 is a schematic perspective view of the partition wall showing the orientation state of the communication passages formed in the partition wall shown in FIGS. 2A and 2B. FIG. 5 is a schematic bottom view showing the orientation state of the communication passage in one protrusion of the partition wall shown in FIGS. 2A and 2B. FIG. 6 is a schematic bottom view showing the orientation state of the communication passage in one protrusion of the partition wall shown in FIGS. 2A and 2B. 7A and 7B are cross-sectional views of a main part of a partition wall (sub-chamber) in the combustion chamber of one cylinder of the sub-chamber engine according to the second embodiment, and FIG. 7A shows the flow of fluid in the combustion stroke. FIG. 7B shows the flow of fluid during the compression stroke. FIG. 8 is a cross-sectional view of a partition wall (sub chamber) in the combustion chamber of one cylinder of the sub chamber engine according to the third embodiment. FIG. 9 is a cross-sectional view of a partition wall (sub chamber) in the combustion chamber of one cylinder of the sub chamber engine according to the fourth embodiment. FIG. 10 is a vertical cross-sectional view of a main part of a partition wall in the combustion chamber of one cylinder of the sub-chamber engine according to the fifth embodiment.

Hereinafter, the sub-chamber engine as an embodiment will be described with reference to the drawings. The embodiments shown below are merely examples, and there is no intention of excluding the application of various modifications and techniques not specified in the following embodiments. Each configuration of the present embodiment can be variously modified and implemented without departing from the gist thereof. In addition, it can be selected as needed, or can be combined as appropriate.

[First Embodiment]
[overall structure]
The sub-chamber engine (internal combustion engine, including a gasoline engine and a diesel engine; hereinafter, also simply referred to as “engine”) 1 according to the present embodiment is a multi-cylinder engine, and each cylinder is shown in FIG. 1A. As described above, the cylinder 11 formed in the cylinder block 2, the piston 12 reciprocating in the cylinder 11, the intake port 13 and the exhaust port 14 formed in the cylinder head 3, and the intake valve provided in the intake port 13 The exhaust valve 16 provided in the 15 and the exhaust port 14 is provided.
In the present embodiment, as shown in FIG. 1B, two intake ports 13 (15 intake valves) and two exhaust ports 14 (exhaust valves 16) are provided, but the number of intake ports (number of intake valves). ) And the number of exhaust ports (the number of exhaust valves) are not limited to this.

On the cylinder head 2 side (upper middle of FIG. 1A) in the cylinder 11, the combustion chamber 20 is partitioned by the inner wall of the cylinder 11, the top surface 12a of the piston 12, and the cylinder head 2. An intake port 13 opened and closed by an intake valve 15 and an exhaust port 14 opened and closed by an exhaust valve 16 are connected to the combustion chamber 20 so as to communicate with each other. Here, the top of the combustion chamber 20 is formed in a pent roof shape having an intake slope provided with the intake valve 15 and an exhaust slope provided with the exhaust valve 16.

A fuel injection valve 17 is provided on the peripheral wall 11a of the top portion (upper part in FIG. 1A) in the cylinder 11, and the engine 1 of the present embodiment is an in-cylinder injection engine (in-cylinder injection engine) that injects fuel directly into the cylinder 11. It is configured as a direct injection engine). In the present embodiment, only the fuel injection valve 17 that injects fuel directly into the cylinder 11 is provided, but in addition to this, a fuel injection valve for port injection that injects fuel into the intake port 13 may be added. ..

Further, the engine 1 according to the present embodiment uses a passive system in which the fuel injected by the fuel injection valve 17 is supplied into the sub chamber 22 through the space in the main chamber 21. However, the engine 1 according to the present case may adopt an active method in which fuel is directly supplied to the sub-chamber 22.
In the present embodiment, a configuration example in the case of both the passive method and the active method will be described with respect to the fuel supply.

The engine 1 according to the present embodiment is a spark-ignition engine, and is located in the combustion chamber 20 at the top of the combustion chamber 20 (here, the top of the pent roof shape) 20a, in the vicinity of the bore center line CL or the bore center line CL. The spark plug 18 is equipped with the spark discharge unit 18a exposed. However, the engine 1 according to the present case also includes a compression ignition engine not provided with a spark plug 18. When the air-fuel mixture is ignited by the spark plug 18, it is usually referred to as "igniting", but here, it is referred to as "igniting" or "igniting" in the sense of including compression ignition.

[Composition of main room and sub room]
The top 20a of the combustion chamber 20 is provided with a partition wall 23 that divides the internal space of the combustion chamber 20 into a main chamber (main combustion chamber) 21 and a sub chamber (sub combustion chamber) 22. The partition 23 is arranged so as to cover the space where the spark discharge portion 18a of the spark plug 18 is exposed, and the internal space (the space including the spark discharge portion 18a) covered by the partition 23 in the combustion chamber 20 is the sub chamber 22. The external space of the partition wall 23 in the combustion chamber 20 is the main chamber 21.

As shown in FIG. 1C, the partition wall 23 is formed with a plurality of (six in this embodiment) communication passages (also referred to as “nozzles”) 24 that communicate the main chamber 21 and the sub chamber 22. These plurality of communication passages 24 serve as a flow path for introducing a part of the air-fuel mixture (air and fuel) in the main chamber 21 into the sub chamber 22 in the compression stroke, and are formed in the sub chamber 22 in the combustion stroke. It serves as a flow path for jet-injecting the generated flame toward the main chamber 21 side.

A part (one in this case) 24A of the plurality of communication passages 24 is configured as a linear communication passage, and a fuel inflow for introducing the fuel injected into the main chamber 21 from the fuel injection valve 17 into the sub chamber 22. It also functions as a continuous passage.
Further, the fuel injection valve 17 includes an injection port for supplying fuel into the main chamber 21 and an injection port for supplying fuel into the sub chamber 22.
[Composition of main room and sub room]

In the sub-chamber 22, in the compression stroke, the fuel (air-fuel mixture containing a large amount of fuel) introduced through the fuel inflow passage 24A is ignited by using the ignition plug 18 at a predetermined timing, and this ignition causes the inside of the sub-chamber 22 to ignite. The flame formed in the above is jetted from the sub-chamber 22 into the main chamber 21 through a plurality of communication passages 24 to ignite the air-fuel mixture in the main chamber 21 and burn it. Such an ignition system, also called a jet ignition system, is effective in igniting a dilute mixture and promoting combustion, and can be applied to lean burn in the main chamber 21 or a large amount of EGR, thereby improving fuel efficiency. Become.
However, the engine according to this case shall also include a compression ignition engine not provided with a spark plug 16. When the air-fuel mixture is ignited by the spark plug 18, it is usually referred to as "igniting", but here, it is referred to as "igniting" or "igniting" in the sense of including compression ignition.

[Structure of protrusions and passages]
By the way, on the outer surface of the sub chamber 22 (that is, the outer surface of the partition wall 23), where the communication passage 24 (excluding the fuel inflow communication passage 24A) is formed, as shown in FIGS. 2A and 2B, the outside A protruding portion 40 is provided (on the main chamber 21 side). Note that FIGS. 2A and 2B show configuration examples corresponding to the passive fuel supply. In the case of fuel supply by the active method, a configuration in which a protrusion 40 is provided at a position where the fuel inflow passage 24A is arranged is also suitable. In the present embodiment, the protrusion 40 is formed in a substantially hemispherical shape. The protruding shape of the protruding portion 40 is preferably a smooth curved surface shape such as a substantially hemispherical shape, but is not limited to a smooth curved surface shape such as a substantially hemispherical shape, and various shapes can be adopted.

Further, as shown by arrows L1 and L2 of the alternate long and short dash line in FIGS. 3, 4, 5, and 6, the

communication passages

24B and 24C formed in the protrusion 40 are bent in the protrusion 40. The direction in which the flame enters the communication passage 24 from the sub chamber 22 side (see arrow L1) and the direction in which the flame jets out from the communication passage 24 into the main chamber 21 (see arrow L2) are different.

In the case of the present embodiment, as shown in FIG. 5, there are a plurality of passages 24B formed in the protrusion 40 (here, in the direction from the sub chamber 22 toward the main chamber 21) in the direction in which the flame is ejected. It is configured as a branch passage that branches into two). Further, as shown in FIG. 6, the communication passage 24C formed in the protrusion 40 is bent in the direction in which the flame is ejected (the direction from the sub chamber 22 toward the main chamber 21) without branching. It is configured as a bent passage.

That is, the portion 241 on the incident side (sub chamber 22 side) of the flame in the branch passage 24B (hereinafter referred to as the incident side portion) 241 is in the vicinity of the spark discharge portion 18a of the spark plug 18 (indicated by reference numeral P in FIG. 4). ) Toward the branch passage 24B, and the portion (hereinafter referred to as the ejection side portion) 242 of the passage 24 on the ejection side (main chamber 21 side) branched at the branch portion indicated by reference numeral B in FIG. 4 is The flames ejected from the adjacent branch passages 24B and the bent passages 24C are bent and formed on the side of the adjacent passages 24 with respect to the incident side portion 241 so that the flames ejected from each other collide with each other.

Similarly, the portion (hereinafter referred to as the incident side portion) 241 of the flame incident side (sub chamber 22 side) in the branch passage 24C is in the vicinity of the spark discharge portion 18a of the spark plug 18 (reference numeral P in FIG. 4). 242, which is oriented in the direction from the bent passageway 24C (shown) and bent at the bent portion indicated by reference numeral B'in FIG. 4, on the ejection side (main chamber 21 side) (hereinafter referred to as the ejection side portion) Is bent and formed on the side of the communication passage 24 adjacent to the incident side portion 241 so that the flames ejected from the adjacent branch communication passages 24B collide with each other.

Since the protrusion 40 is formed, the degree of freedom of orientation of the ejection side portion 241 of the communication passage 24 is high, and the flame ejected from the adjacent communication passage 24 is located near the outer surface of the partition wall 23 (inner wall surface of the cylinder 11). Can be oriented to collide with each other (before reaching).
Further, as shown by arrows L1 and L2, each part of the communication passage 24 is formed in a straight line with one end side open, so that it can be easily processed by using a drill or the like.

In the present embodiment, since the passive method is used, the fuel injected by the fuel injection valve 17 is introduced from the space in the main chamber 21 into the sub chamber 22 via one fuel inflow passage 24A. 3, As shown by the alternate long and short dash line L3 in FIG. 4, the fuel inflow passage 24A related to the fuel supply is not provided with the protrusion 40 and is not bent, and the passage 24 also faces the inner wall of the sub chamber 22. It is preferable to form the fuel linearly. In this case, as shown in FIG. 6, the bent passage 24C adjacent to the fuel inflow passage 24A is a bent passage in which the ejection side portion 242 is not branched into a plurality of the incident side portion 241 and is only bent. It is composed. Here, of the ejection side portion 242 of the branch passage 24, the passage portion facing the fuel inflow passage 24A is omitted.

When the fuel supply is an active system, the protrusion 40 may be provided at a position where the fuel inflow passage 24A is formed. Further, a branch passage 24B is formed in any of the protrusion 40 of the fuel inflow passage 24A and the protrusion 40 adjacent thereto (the protrusion 40 in which the bending passage 24C is formed in FIGS. 3 and 4). Then, the flames injected from the respective communication passages 24B may collide with each other.

Further, the flow path cross-sectional area S1 on the inlet side (incident side portion 241) and the flow path cross-sectional area S2 on the outlet side (spout side portion 242) in the direction in which the flame of the communication passage 24 is ejected are cut off from the flow path on the outlet side. The area S2 is set so as to be equal to or less than the flow path cross-sectional area S1 on the inlet side (S1 ≧ S2). When the outlet side (spout side portion 242) of the branch passage 24B is branched into a plurality of (here, two), the flow path cross-sectional area S2 on the outlet side is the total of the branched flow path cross-sectional areas. And.
At this time, for example, when the flow path cross-sectional area S2 on the outlet side is set smaller than the flow path cross-sectional area S1 on the inlet side (S1> S2), the flow path cross-sectional area of the incident side portion 241 is set to Sa, and the flow path cross-sectional area on the ejection side portion is set to Sa. Assuming that the cross-sectional area of the flow path of 242 is Sb, S1 = Sa and S2 = 2Sb, so Sa> 2Sb.
Thereby, the ejection intensity of the flame of the communication passage 24 can be improved.

[Fuel injection and combustion]
In the present embodiment, fuel is injected from the fuel injection valve 17 into the main chamber 21 at the beginning of the intake stroke, and fuel is injected from the fuel injection valve 17 into the sub chamber 22 via the main chamber 21 at the end of the subsequent compression stroke. NS. When port injection is adopted, port injection is performed in the exhaust stroke, and fuel is supplied into the main chamber 21 together with the intake air in the intake stroke. Then, the air-fuel mixture formed in the sub-chamber 22 is ignited at the end of the compression stroke, and the flame formed in the sub-chamber 22 due to this ignition is jet-sprayed into the main chamber 21 via the plurality of communication passages 24. The air-fuel mixture in the main chamber 21 is ignited and burned.

[Action and effect]
According to the sub-chamber engine according to the present embodiment, in the case of passive fuel supply, when fuel is injected into the sub-chamber 22 from the fuel injection valve 17 via the main chamber 21 at the end of the compression stroke, The injected fuel is introduced into the sub chamber 22 via one fuel inflow communication passage 24A. In the case of active fuel supply, the fuel is introduced directly into the sub chamber 22.
Then, at the end of the compression stroke, the air-fuel mixture formed in the sub chamber 22 is ignited, and the flame formed in the sub chamber 22 due to this ignition is jetted into the main chamber 21 via the plurality of communication passages 24. It is ejected to ignite the air-fuel mixture in the main chamber 21 and burn it.

At this time, the jet flames ejected from the respective passages 24 branch and collide with the jet flames ejected from the adjacent passages 24. By causing the jet flames to interfere with each other at a plurality of locations around the sub chamber 22, it is possible to evenly enhance the turbulence of the flames around the sub chamber 22. As a result, the turbulence of the flame in the main chamber 21 becomes stronger, the combustion in the main chamber 21 is promoted, and the thermal efficiency of the engine 1 is enhanced.

Further, since the two jet flames collide with each other, the penetration force of the jet flames can be suppressed, the jet flames can be suppressed from reaching the wall surface of the combustion chamber 20, the heat loss can be reduced, and the thermal efficiency can be improved. ..

Further, if the communication passage 24 adjacent to the fuel inflow communication passage 24A is the branch communication passage 24B and the ejection side portion 242 faces on the extension line on the main chamber 21 side of the fuel inflow communication passage 24A, the fuel inflow communication A part of the fuel that should go to the passage 24A goes to the ejection side portion 242 of the branch passage 24, and the fuel is sent from the fuel inflow passage 24A to the key point (spark plug 18 spark discharge portion 18a) in the sub chamber 22. May not be able to be supplied intensively.

However, in the present embodiment, the communication passage adjacent to the fuel inflow communication passage 24A is a bending communication passage 24C in which the flow path portion facing the fuel inflow communication passage 24A is omitted and is bent without branching. It is possible to prevent the fuel toward the passage 24A from being dispersed in the adjacent bent passage 24C. As a result, fuel can be supplied to the vicinity of the spark discharge unit 18a to generate a rich air-fuel mixture having good ignitability.

Further, the flow path cross-sectional area S2 on the outlet side (spouting side portion 242) is smaller than the flow path cross-sectional area S1 on the inlet side (incident side portion 241) in the direction in which the flame of the communication passage 24 is ejected (S1> S2). ) Since it is set, the effect of improving the ejection intensity of the flame of the communication passage 24 can also be obtained.

Further, in the case of passive fuel supply, if the protrusion 40 is not provided, the fuel inflow passage 24A collides with the outer surface of the partition wall 23 around the fuel inflow passage 24A and is not introduced into the sub chamber 22 from the fuel inflow passage 24A. The fuel flows along the outer surface of the partition wall 23, reaches the side opposite to the injector across the bore center line CL, and forms a rich air-fuel mixture. When this rich mixture is close to the stoichiometric mixture ratio, a large amount of NOx is generated.

In the present embodiment, since the two protrusions 40 are arranged at positions sandwiching the opening of the fuel inflow passage 24A, the fuel inflow passage 24A collides with the outer surface of the partition wall 23 around the fuel inflow passage 24A. Although the fuel that has not been introduced into the sub-chamber 22 flows along the outer surface of the partition wall 23, it may collide with the outer surface of the protrusion 40 and disperse at the periphery of the protrusion 40 to form a rich air-fuel mixture. It is suppressed. Therefore, the generation of NOx can be suppressed.

Further, when the protrusion 40 is present, the jet flame jetted from the sub chamber 22 to the main chamber 21 through the communication passage 24 can be supplied to a position farther from the sub chamber 22 than when the protrusion 40 is not present. During combustion in the main chamber 21, the influence of the partition wall 23 is reduced and combustion is promoted. Furthermore, since the protrusion 40 is made solid and the jet flame passage (continuous passage) is lengthened, the kinetic energy is consumed by that amount, which leads to the suppression of the penetration force of the jet flame, and the combustion chamber of the jet flame. It is possible to suppress the arrival at the wall surface of 20 and reduce the heat loss, and the thermal efficiency is improved.

As shown in FIG. 1C, on the outer surface of the sub chamber 22 (that is, the outer surface of the partition wall 23), the direct injection fuel from the fuel injection valve 17 is formed around the opening through which the fuel inflow passage 24A opens. It is also preferable that the recess 30 having the receiving surface 30a that collides is formed. As a result, the fuel injected into the main chamber 21 collides with the receiving surface 30a of the recess 30 on the outer surface of the sub chamber 22, so that fuel splitting and vaporization can be promoted. The introduction of fuel into the sub-chamber 22 can be promoted. As a result, fuel with promoted splitting and vaporization can be supplied to the vicinity of the spark discharge portion 18a, the combustibility in the sub chamber 22 is improved, and then from the sub chamber 22 to the main chamber 21. The eruption of flame can be stabilized.

[Second Embodiment]
The sub-chamber engine according to the second embodiment has a different passage configuration from the first embodiment.
In the present embodiment, as shown in FIG. 6, the bent passages 24C that are bent and formed without branching are arranged side by side in an annular shape as shown in FIGS. 7A and 7B. The incident side portion 241 of each bending passage 24C is oriented on the line passing through the bore center line CL (radiation direction), and the ejection side portion 242 is oriented in a direction inclined in the same direction with respect to the radiation direction. ..

The outside of the sub-chamber 22 in the portion where the bent passages 24C are arranged in an annular shape is an annular space in the main chamber 21, and as shown in FIG. 7A, the flame injected into the annular space is generated in the combustion stroke. Work together to create a swirl flow in the annular space.

According to the present embodiment, in the combustion stroke, a strong swirl flow is formed in the annular space in the main chamber 21 by the jet flame injected from each bending passage 24C. Therefore, this strong swirl flow causes the main chamber 21 to have a strong swirl flow. Combustion is promoted.

Further, since the incident side portion 241 of each bending passage 24C is oriented on the line passing through the bore center line CL (radiation direction), the fluid (air or air-fuel mixture) in the main chamber 21 enters the sub chamber 22. In the compression step, as shown in FIG. 7B, a swirl flow is not formed in the sub chamber 22, and the spark plug 18 has an effect of facilitating spark ignition.

When the communication passage 24 is not bent, if the ejection side portion of the communication passage 24 is oriented in a direction in which it is inclined with respect to the radiation direction, the incident side portion of the communication passage 24 is also inclined with respect to the radiation direction. By bending the communication passage 24, the direction of the incident side portion 241 and the direction of the ejection side portion 242 can be set in different directions.

Therefore, it is possible to achieve both the formation of a strong swirl flow by the jet flame in the combustion stroke and the inflow of gas into the sub chamber 22 suitable for spark ignition in the compression step.
Moreover, by providing the protrusion 40 and forming the communication passage 24 in the protrusion 40, the degree of freedom in the direction of the ejection side portion 242 is increased, and a strong swirl flow can be easily formed in the main chamber 21 in the combustion stroke. Become.

[Third Embodiment]
The sub-chamber engine according to the third embodiment has a different passage configuration from the first and second embodiments.
In the present embodiment, as shown in FIG. 8, each of the six bending passages 24 is composed of the bending passages 24C, and the six bending passages 24C are divided into three sets so as to form two adjacent pairs. ing. In each pair of bending communication passages 24C, the direction of the incident side portion 241 is oriented on the line passing through the bore center line CL (radiation direction), and the direction of the ejection side portion 242 is such that the jet flames collide with each other. It is oriented in a direction that locks in the opposite direction to the radial direction.

In this way, even if the communication passage 24 is bent without branching, it can collide with the jet flame ejected from the adjacent communication passage 24, and the jet flames interfere with each other as in the first embodiment. By doing so, it is possible to equalize the strengthening of the turbulence of the flame around the sub-chamber 22. As a result, the turbulence of the flame in the main chamber 21 becomes stronger, the combustion in the main chamber 21 is promoted, and the thermal efficiency of the engine 1 is enhanced.
Further, the penetration force of the jet flame can be suppressed, the reach of the jet flame to the wall surface of the combustion chamber 20 can be suppressed, the heat loss can be reduced, and the thermal efficiency can be improved.

[Fourth Embodiment]
The sub-chamber engine according to the fourth embodiment has a different passage configuration from the first to third embodiments.
In the present embodiment, as shown in FIG. 9, six communication passages 24 are composed of two linear communication passages 24A and four bending communication passages 24C. Two sets of these are provided in a combination in which two bent passages 24C are arranged so as to sandwich the linear passage 24A. In the case of passive fuel supply, one of the two linear passages 24A is a fuel inflow passage.

The linear communication passage 24A is oriented on a line (radial direction) passing through the bore center line CL, and the direction of the ejection side portion 242 of the two bending communication passages 24C arranged so as to sandwich the linear communication passage 24A is The jet flames are oriented in a direction in which they are locked in opposite directions to the radial direction so that the jet flames collide with each other on the path of the jet flames from the linear communication passage 24A.

Even with such a configuration, as in the first and third embodiments, the jet flames interfere with each other, so that the reinforcement of the turbulence of the flames around the sub chamber 22 can be equalized, and the reinforcement in the main chamber 21 can be equalized. The turbulence of the flame becomes stronger, the combustion in the main chamber 21 is promoted, and the thermal efficiency of the engine 1 is enhanced.
Further, the penetration force of the jet flame can be suppressed, the reach of the jet flame to the wall surface of the combustion chamber 20 can be suppressed, the heat loss can be reduced, and the thermal efficiency can be improved.

[Fifth Embodiment]
The sub-chamber engine according to the fifth embodiment has a different passage configuration from the first to fourth embodiments.
In the present embodiment, as shown in FIG. 10, a branch passage is applied to all of the six passages 24. However, the

ejection side portions

242 and 242 that branch into two branch into an upper (first direction) side and a lower (second direction) side along the axial direction of the cylinder (direction of the bore center line CL). It is configured as an axial dichotomous passage 24D.

By branching the flame passage into two or more vertically in this way, the flame quickly hits the wall surface of the combustion chamber 20 (the top surface of the cylinder head 3 and the piston 12), and the flame flow can be disturbed. Combustion can be promoted and the air-fuel mixture in the main chamber 21 can be ignited quickly.

[others]
The configuration of the sub-chamber engine described above is an example. For example, the arrangement of the sub chamber 22, that is, the partition wall 23 for partitioning the sub chamber 22, is not necessarily limited to the vicinity of the bore center line CL or the bore center line CL of the top 20a of the combustion chamber 20.
Further, the direction of the central axis of the sub chamber 22 and the direction of the bore central axis CL do not necessarily have to be the same, and even if the central axis of the sub chamber is provided so as to be inclined with respect to the bore central axis CL. good.

In any case, by bending the communication passage 24 at the protrusion 40, the ejection direction of the jet flame from the communication passage 24 can be set with a high degree of freedom, and the jet flames not only collide with each other but also improve combustion. The ejection direction of the jet flame can be appropriately set for various purposes.

Further, in each of the above embodiments, the protrusion 40 is formed solidly, but the protrusion 40 may be formed in a hollow shape by denting the sub chamber 22 side of the protrusion 40 in a concave shape. The passage 24 may be formed in a straight shape without bending or branching.
If at least the surface of the partition wall 23 on the main chamber 21 side is provided with the protrusion 40 protruding toward the main chamber 21, the fuel collides with the outer surface of the protrusion 40 (the surface on the main chamber 21 side) and the protrusion It is possible to suppress the formation of a rich air-fuel mixture in the main chamber 21 by dispersing at the periphery of 40, and to suppress the production of NOx.

Further, the jet flame injected from the sub chamber 22 to the main chamber 21 through the communication passage 24 can be supplied to a position farther from the sub chamber 22 than in the case where the protrusion 40 is absent, and the combustion in the main chamber 21 can be performed. At this time, the influence of the partition wall 23 is reduced and combustion is promoted, which is obtained.

1 Sub-chamber engine (engine)
2 Cylinder block 3 Cylinder head 11 Cylinder 12 Piston 13 Intake port 14 Exhaust port 15 Intake valve 16 Exhaust valve 17 Fuel injection valve 18 Spark plug 18a Spark discharge part 20 Combustion chamber 20a Top of combustion chamber 20 21 Main chamber (main combustion chamber)
22 Sub-chamber (sub-combustion chamber)
23 partition wall 24 continuous passage (nozzle)
24A straight passage (fuel inflow passage)

24B Branch passage

24C Bending passage 24D Axial bifurcation passage 241 Incoming side part of the connection 24 242 Ejection side part of the connection 24 40 Projection CL bore center line

Claims

A main room, a sub-chamber partitioned by the main room and a partition wall, and a plurality of communication passages provided in the partition wall and communicating the main room and the sub-chamber are provided.
A sub-chamber engine that ignites the air-fuel mixture in the main chamber by ejecting a flame formed in the sub-chamber by igniting the air-fuel mixture in the sub-chamber into the main chamber through the communication passage.
The surface of the partition wall on the main chamber side is provided with a protrusion protruding toward the main chamber.
A sub-chamber engine characterized in that the connecting passage is provided in the protrusion.
A sub-chamber engine characterized in that the communication passage provided in the protrusion is bent in the protrusion.
The sub-chamber engine according to claim 2, wherein the communication passage includes a branch communication passage that is branched in a plurality of directions in the direction in which the flame is ejected.
The branch passage is branched into two, a side in the first direction along the axial direction of the cylinder in which the main chamber and the sub chamber are formed, and a side in the second direction opposite to the first direction. The sub-chamber engine according to claim 3, wherein the sub-chamber engine includes a bifurcated passage in the axial direction.
The sub-chamber according to any one of claims 2 to 4, wherein the communication passage includes a bending communication passage that is bent without branching in the direction in which the flame is ejected. Formula engine.
The sub-chamber type according to any one of claims 1 to 5, wherein at least two of the passages are oriented so that the ejected flames collide with each other. engine.
Claims 1 to 6 are characterized in that the flow path cross-sectional area S2 on the outlet side in the direction in which the flame is ejected in the communication passage is set to be equal to or less than the flow path cross-sectional area S1 on the inlet side in the direction in which the flame is ejected. The sub-chamber engine according to any one of the above items.
The communication passage includes a bending communication passage that is bent without branching in the direction in which the flame is ejected.
The invention, wherein the outlet side of the plurality of bent passages from which the flame is ejected is oriented in a direction in which the flame is inclined in the same direction with respect to the radial direction from the clothing chamber to the main chamber. The sub-chamber engine described in 2.
A fuel injection valve that injects fuel into the main chamber and
It is provided with a fuel inflow communication passage which is a part of the plurality of communication passages and introduces the fuel injected from the fuel injection valve into the sub chamber.
The sub-chamber engine according to any one of claims 1 to 8, wherein at least two of the protrusions are arranged at positions sandwiching an opening of the fuel inflow communication passage.
The sub-chamber according to claim 9, wherein a recess having a receiving surface on which the direct-injection fuel from the fuel injection valve collides is formed around the opening of the fuel inflow communication passage. Formula engine.