JP2002266645A - Engine, its operating method and auxiliary combustion chamber mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the technique capable of providing high compression ratio and high efficiency by injecting the fuel to a main combustion chamber 1 with high pressure without using a complex and expensive fuel injection device, in an engine 100 provided with the main combustion chamber 1 and the auxiliary combustion chamber 10 communicated through a communication passage 23, and a fuel supply means 30 and an ignition means 32 mounted in the auxiliary chamber 10. SOLUTION: This engine is provided with a control valve 14 for closing the communicating passage 21 in a compression stroke, and opening the communicating passage 23 in a combustion stroke, a supply passage 40 for connecting the main combustion chamber 1 and an ignition means 32 side of the auxiliary combustion chamber 10, and a supply valve 41 for opening the supply passage 40 in the compression stroke and closing the supply passage 40 in the combustion stroke, the fresh air I is supplied to the auxiliary chamber 10 to which the fuel G is supplied, through the supply passage 40 in the compression stroke to form a combustible zone X at an ignition means 32 side of the auxiliary chamber 10, and an over-rich zone Y on the communicating passage 23 side of the auxiliary chamber 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a main chamber formed in a cylinder, a sub-chamber communicating with the main chamber via a communication passage, fuel supply means for supplying fuel to the sub-chamber, The present invention relates to an engine having an ignition means for igniting the fuel in a sub-chamber and an operation method thereof, and more particularly to a sub-chamber mechanism constituted by the sub-chamber.

[0002]

2. Description of the Related Art In general, such engines can be broadly classified into spark ignition engines (hereinafter referred to as SI engines) and diesel engines.

[0003] In an SI engine, a mixture of air and fuel, which is an example of an oxygen-containing gas, is sucked into a combustion chamber and compressed, and then ignited by a spark plug as ignition means and burned. The ideal cycle of such an SI engine is considered to be an Otto cycle (constant volume heating cycle), and the thermal efficiency can be improved by increasing the compression ratio and performing lean combustion. Further, in the case of the SI engine, there is a stratified air supply system as a lean combustion system which is effective in reducing exhaust gas and improving fuel efficiency due to a decrease in flame temperature, an improvement in cycle efficiency, a decrease in pumping loss, etc., particularly at a partial load. With the stratified charge system, a mixture that has an equivalence ratio within the combustion range where ignition is easy is created around the ignition plug, and a lean region where a mixture that is thinner than the mixture around the ignition plug exists outside the mixture. Then, first, an air-fuel mixture whose equivalence ratio is within the combustion range is ignited and burned, and the air-fuel mixture in the lean region is burned by the flame, thereby burning the lean air-fuel mixture as a whole. As an example of the stratified charge type combustion chamber structure, there is provided a fuel injection valve that directly injects fuel into the combustion chamber, and forms a combustible air-fuel mixture particularly near an ignition plug to stably burn by jetting the fuel into the combustion chamber. is there.

Further, in a diesel engine, fuel is injected by a fuel injection device into a high-temperature and high-pressure combustion chamber having a piston position near a top dead center position and self-ignited.
Ideally, it is configured to operate on a diesel cycle (constant pressure cycle). In the diesel cycle, as in the case of the SI engine, there is no occurrence of pressure oscillation, which is called knocking, caused by self-ignition of the final combustion portion (end gas) in the flame propagation in the combustion chamber, and the compression ratio is relatively high. As a result, the thermal efficiency can be improved.

[0005]

However, in the case where the efficiency is to be improved by directly injecting fuel into the combustion chamber as in the case of an SI engine or a diesel engine employing the above-described stratified charge system, the compression stroke is not sufficient. It is necessary to provide a complicated fuel injection device or the like for injecting fuel into a relatively high pressure combustion chamber. In particular, when the fuel is a gaseous fuel such as natural gas, it is difficult to sufficiently pressurize the gaseous fuel and directly inject it into the high-pressure combustion chamber, which requires a complicated and expensive fuel injection device.

Accordingly, the present invention has been made in view of the above circumstances,
It aims to realize a highly efficient engine with a high compression ratio by injecting fuel into the combustion chamber at high pressure without the need for complicated and expensive fuel injection equipment. It is an object of the present invention to provide a high-efficiency engine applicable to an engine to be used.

[0007]

Means for Solving the Problems [Structure 1] In an engine according to the present invention, as described in claim 1, a main chamber formed in a cylinder and a sub-chamber communicating with the main chamber via a communication passage. A fuel supply means for supplying fuel to the sub-chamber, and an ignition means for igniting the fuel in the sub-chamber, wherein the communication path is closed during a compression stroke, and the combustion path is closed during a combustion stroke. A control valve for opening a communication passage, a supply path connecting the main chamber and the sub-chamber with the ignition means side, and a supply path for opening the supply path in the compression stroke, and connecting the supply path in the combustion stroke. And a supply valve that closes.

[Effects] That is, in an engine having a main chamber and a sub-chamber in which the combustion chambers are communicated with each other by a communication passage, the fuel supply means is provided by providing the fuel supply means as in this configuration. Thus, for example, when the pressure in the main chamber and the sub chamber is still in a low pressure state, in other words, in the case of a four-stroke engine, at the beginning of the intake stroke or the compression stroke, or in the case of a two-stroke engine, the scavenging stroke or At the beginning of the compression stroke, a so-called fuel supply step of supplying fuel to the sub-chamber and forming an air-fuel mixture in the sub-chamber can be performed.
The equivalence ratio of the air-fuel mixture formed in the sub-chamber in this way depends on the combustion until the air sucked into the main chamber or the fresh air which is a lean air-fuel mixture is supplied from the main chamber to the sub-chamber in the compression stroke. It is kept above the limit, that is, in a fuel rich state.

Then, in the next compression stroke, the main chamber is compressed by the piston, and the fresh air sucked into the main chamber is supplied to the sub-chamber by this compression. The fresh air is supplied to the sub-chamber through the communication passage for ejecting the flame torch or the air-fuel mixture into the main chamber from the main chamber. However, in the engine of the present invention, the fresh air is supplied to the sub-chamber instead of the communication passage. Can supply fresh air from the main chamber to the ignition plug side of the sub chamber. Therefore, in the compression stroke, when fresh air sucked into the main chamber is supplied to the sub-chamber, the fresh air can be supplied to a preferable portion on the side of the ignition plug, and the equivalent amount of the flammable range around the ignition plug is favorably obtained. A mixture, which is a ratio, can be formed.

According to a second aspect of the present invention, in addition to the configuration of the engine according to the first aspect, the engine according to the present invention further comprises the sub-chamber to which the fuel is supplied by the fuel supply means. In the compression stroke, the fresh air sucked into the main chamber is supplied through the supply path, and a combustible region where an air-fuel mixture having an equivalence ratio within a combustion range exists is located on the ignition means side of the sub chamber. In addition to the above, a rich region in which an air-fuel mixture having an equivalence ratio equal to or higher than the upper limit of combustion exists is formed on the side of the communication passage of the sub-chamber.

[Function and Effect] In addition, fuel is supplied to the sub-chamber by the supply passage provided with the supply valve and the control valve provided in the communication passage, and the equivalent ratio of the equivalent ratio which is equal to or higher than the upper combustion limit is supplied to the sub-chamber. For example, at the beginning of the compression stroke after forming the air-fuel mixture, the communication passage is closed by the control valve, and fresh air sucked into the main chamber is supplied to the ignition plug side of the sub-chamber through the supply path, and is supplied to the sub-chamber. A so-called fresh air supply step of forming the combustible region and the rich region can be performed.

After the fuel supply step and the fresh air supply step are sequentially performed, the engine of the present invention activates the ignition means provided in the sub-chamber in the latter half of the compression stroke to cause combustion of the sub-chamber. The mixture in the possible region is ignited and burned. Then, the pressure wave generated by the combustion in the combustible region of the sub-chamber is propagated to the rich region formed on the communication passage side, and the mixture having an equivalent ratio equal to or higher than the upper combustion limit of the rich region is ignited. Instead, the high pressure is injected into the main chamber through the communication passage.

Therefore, the engine of the present invention having the above-mentioned unique sub-chamber mechanism has a complicated and expensive fuel injection device such as a conventional diesel engine, and a stratified charge system for directly injecting fuel into the combustion chamber. The fuel-rich mixture formed in the sub-chamber is injected at high pressure into the main chamber by utilizing the pressure rise due to combustion in the combustible region of the sub-chamber without the need for a fuel injection device or the like. Driving method can be performed. The engine of the present invention is a diesel engine that injects air-fuel mixture into the main chamber at a high pressure and self-ignites even if the fuel is gaseous fuel, or an air-fuel mixture near the spark plug provided in the main chamber. And injects the mixture to ignite the mixture to burn the surrounding lean mixture, thereby enabling a stratified charge type SI engine to be constructed, thereby achieving higher efficiency.

According to a third aspect of the present invention, in the engine according to the third aspect, in addition to the configuration of the engine according to the second aspect, the air-fuel mixture ejected from the communication passage in the main chamber is self-ignited. It is characterized by being burned.

[Effects] That is, the engine of the present invention
For example, the compression ratio is set to a high compression ratio of about 16 to 18, and at the time when the piston position is near the top dead center position, the air-fuel mixture in the rich region of the sub-chamber is injected into the main chamber via the communication passage. It can be configured as a so-called diesel engine that self-ignites. Further, the fuel supply means of the engine configured as a diesel engine as described above includes:
Since the fuel can be configured to be supplied at a relatively low pressure, a gaseous fuel such as natural gas can be easily used as the fuel.

[Structure 4] In the engine according to the present invention, as described in claim 4, in addition to the structure of the engine according to any one of the above structures 1 to 3, the supply valve is provided in the main chamber in the supply path. The supply amount of the fresh air from the to the sub-chamber is configured to be adjustable.

[Function and Effect] As in the present configuration, the supply valve is
The means for supplying fresh air from the main chamber to the sub-chamber with the supply amount adjustment can adjust the equivalence ratio of the air-fuel mixture formed in the sub-chamber and the range of the combustible region formed in the sub-chamber Can be adjusted. Further, the engine of this configuration can increase the amount of fresh air supplied to the sub-chamber by the oxygen-containing gas supply means from the operation of injecting the air-fuel mixture into the main chamber from the communication passage described above, and combust the entire sub-chamber. It is also possible to form an area and switch to an operation in which a flame torch is ejected from the communication passage into the main chamber.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the engine of the present invention will be described with reference to the drawings. The engine 100 according to the present invention shown in FIGS.
And a cylinder 3 forming a main chamber 1 together with the top surface of the piston 2. The piston 2 is reciprocated in the cylinder 3, and the intake valve 4 and the exhaust valve 5 are opened and closed, so that fresh air is mainly discharged. The main chamber 1 takes in the intake, compression, combustion / expansion and exhaust strokes, and outputs the reciprocating motion of the piston 2 by a connecting rod (not shown) as a rotational motion of a crankshaft (not shown). Such a configuration is not different from a normal four-stroke internal combustion engine. Note that, in the engine 100 of the present embodiment,
When the bore diameter of the cylinder 3 is 110 mm, the stroke length of the piston 2 is 106 mm, and the position of the piston 2 is at the bottom dead center position with respect to the combustion chamber volume when the position of the piston 2 is at the top dead center position. The compression ratio, which is the ratio of the capacity of the combustion chamber, is 17. Further, the engine 1 of the present embodiment
The reference numeral 00 indicates that an output of about 15 kW can be obtained by operating the crankshaft at 1200 rpm.

The engine 100 is provided with a city gas (13
A) is used as fuel G. In the intake stroke, the intake valve 4 is opened, and only the air or fresh air I, which is a lean mixture of air and a small amount of fuel, is sucked into the main chamber 1,
In the compression stroke, the sucked fresh air I is compressed to produce fuel G
Is to burn.

Further, the cylinder head 9 of the engine 100 is provided with a sub-chamber 10 which is provided as a combustion chamber of the engine 100 like the main chamber 1 and communicates with the main chamber 1 through a communication passage 23. The structure of the sub chamber mechanism 20 having the sub chamber 10 will be described below. The sub chamber mechanism 20
The capacity of the sub-chamber 10 is 1/1 of the total combustion chamber capacity obtained by adding the capacity of the main chamber 1 when the position of the piston 2 is at the top dead center position.
It is about 0.

A fuel supply valve 30 (an example of a fuel supply means) is provided above the sub-chamber 10, and the fuel G is supplied by the fuel supply valve 30 at a supply pressure of 0.3 MPa (Gauge). 10.

Above the sub-chamber 10, an ignition plug 32 (an example of an ignition means) is provided.
Thus, the fuel G in the sub chamber 10 is ignited.

A control valve 15 is operated in the communication passage 23 of the sub chamber 10 by a cam mechanism or the like. The control valve 15 closes the communication passage 23 during the compression stroke and opens the communication passage 23 during the combustion stroke, as will be described in detail later. Is provided.

In addition to the communication passage 23, the engine 100 is provided with a supply passage 40 for connecting the ignition plug 32 side of the sub-chamber 10 to the main chamber 1. A check valve 41 (an example of a supply valve) that allows only gas flow from the main chamber 1 to the sub-chamber 10 of the passage 40 is provided. The check valve 41 is opened when the pressure difference between the main chamber 1 and the sub-chamber 10 becomes equal to or more than a predetermined pressure difference in the compression stroke, and the fresh air sucked into the main chamber 1 in the previous intake stroke. The flow of I from the main chamber 1 to the sub-chamber 10 toward the spark plug 32 is permitted. Further, the check valve 41 will be described in detail later.
When the pressure of 0 rises, the supply passage 40 is closed. Further, an adjusting means 42 for adjusting the supply amount of fresh air I supplied from the main chamber 1 to the sub-chamber 10 in the compression stroke is provided, and the adjusting means 42 is added to the valve body of the check valve 41. The additional pressure is adjusted to adjust the timing at which the check valve 41 is opened during the compression stroke.

Next, as an operation method of the engine 100 of this embodiment, an operation state in one cycle will be described with reference to the drawings. FIG. 2 shows the engine 1 of the present embodiment.
6 is a flowchart showing an operation state in one cycle of 00.

First, as shown in FIG. 1, the engine 100 performs an intake stroke in which the intake valve 4 is opened, the piston 2 descends through the top dead center, and fresh air I is sucked into the main chamber 1. In this intake stroke, the control valve 15 and the check valve 41 are closed.

Then, when the sub-chamber 10 is still in the low pressure state in the latter stage of the intake stroke or the early stage of the compression stroke, a fuel supply step of supplying the fuel G to the sub-chamber 10 by the fuel supply valve 30 is performed as shown in FIG. Will be Also in this fuel supply step, the control valve 15 and the check valve 41 are in the closed state, and the sub-chamber 1
At 0, a mixture is formed in which the equivalent ratio is equal to or higher than the upper limit of combustion (for example, in the range of 5 to 6), that is, the fuel is kept in a rich state.

In the middle stage of the compression stroke, for example, when the crank angle is 60 ° BTDC, as shown in FIG. 4, when the pressure difference between the main chamber 1 and the sub chamber 10 becomes a predetermined pressure difference, The stop valve 41 is opened, and a fresh air supply step is performed in which fresh air sucked into the main chamber 1 is supplied to the ignition plug 32 side of the sub-chamber 10 via the intake path 40. In the fresh air supply step, the fresh air I is supplied to the sub-chamber 10 on the side of the ignition plug 32, so that the equivalent ratio within the combustion range (for example, 0.65
(Approximately 1.2) is formed in the sub-chamber 10 on the side of the ignition plug 32, and an air-fuel mixture having an equivalent ratio equal to or higher than the upper limit of combustion (for example, 1.2 or more) exists. The dense area Y is formed on the side of the communication passage 23 of the sub chamber 10.

The engine 100 of the present embodiment
As shown in FIG. 5, during the combustion stroke, 20 ° BTDC
In the vicinity, the ignition plug 32 is operated to spark-ignite the air-fuel mixture in the above-described combustible region X and burn it.
The control valve 15 is opened during the period from DC to BDC. Then, a pressure wave generated by combustion in the combustible region X of the sub-chamber 10 is propagated to the rich region Y formed on the communication passage 23 side, and the air-fuel mixture having an equivalent ratio equal to or higher than the upper combustion limit of the rich region Y Is injected into the high-pressure and high-temperature main chamber 1 in the latter half of the compression stroke through the communication passage 23 without ignition. When the pressure in the sub-chamber 10 becomes high, the check valve 41 acts to close the supply passage 40.

In the engine 100, in the combustion / expansion stroke, the fuel-rich mixture injected into the main chamber 1 as described above is compressed into a main chamber having a compression ratio in the range of 16 to 18. Immediately after the fuel is injected into the main chamber 1, it self-ignites and burns using the oxygen of the fresh air I in the main chamber 1. Such a main room 1
The combustion state in the above becomes a state close to a so-called diesel cycle (constant pressure cycle), and the compression ratio of the engine can be set high, and the thermal efficiency can be improved to, for example, about 38%. Further, in one cycle, the equivalent ratio φ of the air-fuel mixture burned in the entire combustion chamber of the main chamber 1 and the sub chamber 1 is, for example, 0.3.
Since lean combustion can be realized at about 5 to 0.5, preferably about 0.4, emission of NOx and the like can be reduced.

In the above embodiment, the main room 1
Is provided with no spark plug, and a fuel-rich mixture formed in the sub-chamber 10 is ejected from the communication passage 23 to the main chamber 1 in a high pressure state, and reacts with the fresh air I in the main chamber 1 to burn. Although a configuration similar to a so-called diesel engine has been described, it is also possible to separately provide an ignition plug in the main chamber 1 and spark-ignite the air-fuel mixture ejected from the communication passage 23.

Further, since the valve seat of the control valve 15 is provided on the main chamber 1 side of the communication path 23, when the fuel G is supplied to the sub chamber 10 in the fuel supply step, the fuel G is connected. Even if the fuel G flows out to the main chamber 1 through the passage 23, the fuel G flowing out to the main chamber 1 can be retained above the main chamber 1, that is, near the communication path 23. Therefore, the fuel G flowing out into the main chamber 1 and staying upward is transferred from the main chamber 1 to the sub chamber 1 in the compression step.
It can be pushed back to the sub-chamber 10 by the new airflow flowing into the zero.

[Another Embodiment] <1> In the above embodiment, the supply amount of fresh air I supplied from the supply passage 40 to the sub-chamber 10 is fixed. To adjust the amount of fresh air I supplied from the main chamber 1 to the sub-chamber to adjust the equivalence ratio of the air-fuel mixture formed in the sub-chamber 10, The range of the formed combustible region X can be adjusted.

For example, when the engine is to be operated at a low load, the rich region Y is formed in the sub chamber 10 as described in the above embodiment, and the air-fuel mixture in the rich region Y is converted into the combustible region X. By using the pressure increase due to the combustion in the above, an operation close to a so-called diesel engine in which high-pressure injection is performed into the main chamber 1 through the communication passage 23 is performed. A relatively high-concentration air-fuel mixture is sucked in, the supply amount of fresh air I supplied to the sub-chamber 10 is increased to form a combustible region X in the entire sub-chamber 10, and the air-fuel mixture in the sub-chamber 10 is ignited. And burn it,
An operation can be performed in which a flame torch is injected into the main chamber 1 through the communication passage 23 to ignite the air-fuel mixture sucked into the main chamber 1. When performing such a high-load operation,
For the purpose of preventing knocking or the like during high-load operation, it is preferable that the compression ratio during high-load operation be lower than that during low-load operation. The compression ratio can be reduced by increasing the difference between the lower dead center position and the lower dead center position, in other words, by increasing the degree of late closing or early closing of the intake valve 4 with respect to the lower dead center position. Also, at the time of starting the engine, the same operation as the high-load operation can be performed, and the engine can be warmed up satisfactorily.

<2> In the above embodiment, an engine using city gas has been described. However, the engine of the present invention exhibits excellent effects by constituting an engine using city gas or the like of gaseous fuel. Such gaseous fuels include C such as hydrogen and propane.
The O or H ₂ is gaseous fuels other than hydrocarbons mainly. Further, it is needless to say that a fuel other than the gaseous fuel can be used. For example, gasoline, alcohol, methanol, ethanol, or any fuel can be used.

<3> In the above embodiment, when changing the rotation speed or load of the engine of the present invention, a rotary valve or the like is provided in the flow path of fresh air I sucked into the cylinder, The load or the rotation speed can be changed by changing the intake pressure according to the opening degree, changing the equivalence ratio of fresh air, the amount of fuel supplied to the sub chamber, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an engine according to the present invention.

FIG. 2 is a chart showing operation timings of the engine shown in FIG. 1;

FIG. 3 is a schematic configuration diagram showing an operating state of the engine shown in FIG. 1;

FIG. 4 is a schematic configuration diagram showing an operating state of the engine shown in FIG. 1;

FIG. 5 is a schematic configuration diagram showing an operating state of the engine shown in FIG. 1;

[Explanation of symbols]

 Reference Signs List 1 main chamber 2 piston 3 cylinder 10 sub-chamber 15 control valve 20 sub-chamber mechanism 23 communication passage 30 fuel supply valve (fuel supply means) 32 ignition plug 40 supply path 41 check valve (supply valve) 42 adjustment means X combustible area Y Rich area A Air (oxygen-containing gas) G Fuel I Fresh air

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02B 23/08 F02B 23/08 A F02D 15/04 F02D 15/04 G F02M 21/02 F02M 21/02 Q (72) Inventor Koji Moriya 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka Gas Co., Ltd. (reference) 3G023 AA01 AB02 AB03 AB06 AC05 AC07 AD12 AD23 AD27 AD30 AG01 3G092 AA01 AA07 AA09 AB07 AB08 AB09 DA01 DA08 DE01S EA03 EA04 FA16 FA31 FA50 GA01 GA06

Claims (6)

[Claims] 1. A main chamber formed in a cylinder, a sub-chamber communicating with the main chamber via a communication passage, fuel supply means for supplying fuel to the sub-chamber, and a fuel supply device for supplying fuel to the sub-chamber. An ignition means for igniting, comprising: a control valve that closes the communication path in a compression stroke and opens the communication path in a combustion stroke; and a side of the main chamber and the sub chamber that is closer to the ignition means. And a supply valve that opens the supply path during the compression stroke and closes the supply path during the combustion stroke. 2. The fresh air sucked into the main chamber is supplied to the sub-chamber to which the fuel has been supplied by the fuel supply means during the compression stroke through the supply passage, so as to be in a combustion range. A combustible region in which an air-fuel mixture having an equivalence ratio exists is formed on the ignition means side of the sub-chamber, and a rich region in which an air-fuel mixture having an equivalence ratio equal to or higher than the upper combustion limit exists is provided in the communication passage of the sub-chamber The engine according to claim 1, wherein the engine is formed on a side. 3. The engine according to claim 2, wherein the air-fuel mixture ejected from the communication passage in the main chamber is self-ignited and burned. 4. The supply valve according to claim 1, wherein the supply valve is configured to adjust a supply amount of the fresh air from the main chamber to the sub-chamber in the supply path. engine. 5. A main chamber formed in a cylinder, a sub-chamber communicating with the main chamber via a communication passage, fuel supply means for supplying fuel to the sub-chamber, and a fuel supply means for supplying fuel to the sub-chamber. An operation method of an engine including an ignition unit for igniting, a control valve capable of opening and closing the communication path, a supply path connecting the main chamber and the sub chamber with the ignition unit. A supply valve capable of opening and closing the supply path, closing the communication path by the control valve, and performing a fuel supply step of supplying the fuel to the sub-chamber by the fuel supply means. In, while the communication path is closed by the control valve, the supply path is opened by the supply valve,
The fresh air sucked into the main chamber is supplied to the sub-chamber through the supply path, and a combustible region where an air-fuel mixture having an equivalence ratio within a combustion range exists is formed on the ignition means side of the sub-chamber. At the same time, a fresh air supply step of forming an enriched region in which an air-fuel mixture having an equivalence ratio equal to or higher than the upper limit of combustion exists on the side of the communication passage in the sub chamber is performed, and in the combustion stroke, the communication passage is controlled by the control valve. While being opened, the air-fuel mixture in the combustible region of the sub-chamber is ignited and burned by the ignition means, and the pressure wave obtained by the combustion in the combustible region causes the rich region of the sub-chamber to be compressed. The method of operating an engine, wherein the air-fuel mixture is jetted into the main chamber through the communication passage, and the air-fuel mixture jetted from the communication passage in the main chamber is burned. 6. A sub-chamber provided in an engine having a main chamber formed in a cylinder and communicating with the main chamber via a communication passage; fuel supply means for supplying fuel to the sub-chamber; A sub-chamber mechanism comprising an ignition means for igniting the fuel in the sub-chamber, comprising a control valve for closing the communication passage in a compression stroke and opening the communication passage in a combustion stroke. A sub-chamber mechanism, comprising: a supply path connecting the sub-chamber with the ignition means side; and a supply valve that opens the supply path in the compression stroke and closes the supply path in the combustion stroke.