JPH09166024A - Prechamber type gasoline engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the staying of non-burnt gas in a prechamber by first supplying highly compressed air to the upper part of the prechamber and starting ignition from the upper part of the prechamber in a prechamber type gasoline engine. SOLUTION: This prechamber gasoline engine is provided with a prechamber structure 3 for forming a prechamber in a cylinder head 13, a sublinking passage 9 communicated through a through-hole 9A with a main linking port 7 communicated with a prechamber lower part 2B and a prechamber upper part 2A. A prechamber opening/closing valve 4 is arranged in a linking port 6, the prechamber linking passage 9 is first opened according to the lifting amount of the prechamber opening/closing valve 4, then the main linking port 7 is opened, the prechamber upper part 2A in the prechamber 2 is ignited, the long- time staying of the non-burnt gas in the prechamber 2 is prevented and thus thermal efficiency is increased by controlling the generation of non-burnt HC.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sub-chamber type gas engine having a sub chamber in a cylinder head and a main chamber on the cylinder side.

[0002]

2. Description of the Related Art Heretofore, as a gas engine, there has been considered a method in which a sub-chamber is provided in a cylinder head, the sub-chamber is made rich in fuel, ignitability is ensured in a lean region, and combustion is stabilized. However, the gas engine uses natural gas, that is, natural gas as fuel, and the fuel is gas. Therefore, when gas is sucked in the suction stroke and then compressed, the air-fuel mixture is highly compressed and its temperature rises, causing a phenomenon of self-ignition, that is, knocking. However, if the compression ratio of natural gas fuel is not less than 12,
It self-ignites. Regarding the thermal efficiency of the engine, there is a phenomenon that the thermal efficiency decreases when the compression ratio is small.

Therefore, in a sub-chamber gas engine, in order to further stabilize the lean combustion, a sub-chamber opening / closing valve is installed in a communication hole that communicates the sub-chamber with the main chamber, and the sub-chamber opening / closing valve is provided during the intake stroke. Keep it closed and inhale only air into the main chamber and introduce natural gas into the sub chamber. Then, the sub-chamber opening / closing valve is opened just before the top dead center of the compression stroke, and air is instantaneously introduced into the sub-chamber due to the pressure difference between the main chamber and the sub-chamber, and the natural gas and air are rapidly mixed and ignited and burned. Then, the lean burn is completed in a short time while flowing from the sub chamber to the main chamber through the communication hole.

[0004]

By the way, the applicant of the present invention has developed a gas engine that solves the above-mentioned problems, and has previously filed as Japanese Patent Application No. 6-124678. The gas engine introduces a gas fuel such as natural gas into the sub chamber,
In addition to increasing the compression ratio by compressing only the intake air in the main chamber,
The cylinder pressure in the sub chamber is detected by a sensor such as a piezoelectric element, and based on this information, the fuel supply valve is operated to control the proper fuel supply amount that matches the load and the rotational speed, and the air in the main chamber is controlled. Ignite in a short period of time by opening the communication hole valve of the communication hole while raising the temperature to high temperature to allow the highly compressed air in the main chamber to flow into the sub chamber and mixing the gas fuel and highly compressed air in the sub chamber all at once. To burn. Moreover, since the auxiliary combustion chamber fuel is rich state is combusted suppressing state generation of NO _X, flame short as much as possible uniform mixture of secondary combustion by causing sprayed once in the main chamber from the auxiliary chamber It is completed in a short time to reduce the generation of NO _x , HC, etc., particularly to improve the thermal efficiency, prevent self-ignition of gas fuel, and prevent knocking.

By the way, in the sub-chamber gas engine, when the sub-chamber opening / closing valve is opened, air flows from the main chamber into the sub-chamber, is rapidly mixed with gas fuel, and is self-ignited to start combustion. ing. In order to perform active combustion with a high air utilization rate in the main chamber, ignition occurs in the region farthest from the main chamber of the sub chamber, combustion progresses, and an unburned mixture or flame is ejected from the sub chamber to the main chamber. Is considered ideal.

However, in the conventional sub-chamber gas engine, the air flowing from the main chamber to the sub-chamber is mixed in the sub-chamber as a whole through the communication port of the sub-chamber opening / closing valve by opening the communication port. Since the ignition position in the room is not specified and ignition occurs in the sub-chamber during air inflow, the pressure in the sub-chamber rises and the amount of air introduced into the sub-chamber is limited.
Therefore, there is a problem that combustion cannot be performed in the sub chamber until the pressure rises enough to eject the gas fuel in the sub chamber into the main chamber. If the gas fuel in the sub-chamber does not burn sufficiently and the pressure does not rise sufficiently, unburned gas stays in the sub-chamber for a long period of time, which deteriorates the efficiency in the high load region. In order to solve this problem, a combustion method in which a part of the gas fuel is supplied to the main chamber in advance before the ignition of the gas fuel in the sub chamber is conceivable. However, if the gas fuel is simply supplied to the main chamber, Since the main chamber becomes a lean air-fuel mixture, there is a problem that the combustion speed becomes slow and the generation of HC, soot, etc., increases.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, in which a sub-chamber structure which constitutes a sub-chamber is arranged in a cylinder head, and a main chamber is constructed on the cylinder side. A sub-chamber opening / closing valve is arranged at a communication port that connects the main chamber and the sub chamber, and a sub-communicating passage opening to the sub chamber lower part and a sub communication chamber upper part is formed in the sub chamber structure to form a compression. Open the sub chamber on-off valve near the end of the stroke, and open the sub communication passage during valve lift to ignite from the upper part of the sub chamber to progress combustion, and from the upper part of the sub chamber to the combustion gas of unburned gas and flame Injecting unburned gas into the main chamber while pushing it out,
An object of the present invention is to provide a sub-chamber gas engine that prevents unburned gas from staying in the sub-chamber for a long period of time, prevents generation of HC and the like, and improves thermal efficiency particularly in a high load region.

According to the present invention, a sub-chamber structure is provided in the cylinder head and forms a sub-chamber arranged substantially at the center of the cylinder, the sub-chamber formed in the sub-chamber structure and the main chamber on the cylinder side. Communication port, a sub-chamber opening / closing valve for opening and closing the communication port, a main communication port opened to the communication port and formed at the lower end of the sub-chamber structure, the communication port and the sub-portion A sub-communicating passage extending from a lower end of the chamber structure to an upper portion of the sub-chamber and opening to an upper portion of the sub-chamber; and a gas fuel supply valve for supplying a gas fuel to the sub-chamber. The present invention relates to a sub-chamber gas engine which is set to open the main communication port after opening the passage.

In this sub-chamber gas engine,
The main chamber is composed of a combustion chamber structure arranged in a cavity formed in the cylinder head, the sub-chamber structure is arranged in a fitting hole formed substantially in the center of the combustion chamber structure, The communication port is formed in the combustion chamber structure, and the sub chamber opening / closing valve is arranged in the communication port of the combustion chamber structure.

Alternatively, in this sub-chamber gas engine,
The main chamber is composed of a combustion chamber structure arranged in a cavity formed in the cylinder head, the sub-chamber structure is arranged in a fitting hole formed substantially in the center of the combustion chamber structure, The communication port is formed in the sub chamber structure, and the combustion chamber structure is formed with a plurality of communication holes communicating with the communication port and circumferentially spaced from each other and extending in the cylinder peripheral direction. A valve is arranged at the communication port of the subchamber structure.

Alternatively, in this sub-chamber gas engine, the main chamber is formed on the cylinder side, the communication port is formed in the sub-chamber structure, and the sub-chamber opening / closing valve is the sub-chamber structure. It is located at the access port.

Further, in this sub-chamber gas engine,
The sub chamber opening / closing valve has a first valve face for opening / closing the communication port and a second valve face for opening / closing the main communication port, and the first valve face connects the first valve face when the sub chamber opening / closing valve is lifted. After opening the mouth, the second valve face opens the main communication port, and the sub communication passage opens between the first valve face and the second valve face. Therefore, according to the valve lift amount of the sub-chamber opening / closing valve, the sub-communication passage has a larger passage area than the main communication opening until the sub-chamber opening / closing valve reaches a predetermined lift amount. Ignition and combustion in the room will progress from the upper part of the sub chamber.

Since the sub-chamber type gas engine is constructed as described above, the sub-chamber opening / closing valve opens the sub-communication passage at the initial stage of valve lift, and then opens the main communication port. It is possible to ignite and burn from the upper portion of the sub chamber to eject unburned gas or flame from the main communication port to the main chamber, and prevent unburned gas from staying in the sub chamber for a long period of time.

In this sub-chamber type gas engine, the gas fuel in the sub-chamber is rapidly mixed with the air flowing from the main chamber to the upper portion of the sub-chamber at high speed through the sub-communication passage to generate a rich air-fuel mixture. It ignites and burns at a rapid rate and primary combustion progresses rapidly to suppress the generation of NO _X. Then, fresh energy is generated in the main chamber by the jet energy of the combustion gas jetted from the main communication port in the lower part of the sub chamber to the main chamber. Entrapment improves the air utilization rate and rapidly burns as a lean mixture to secondary combustion, suppressing the emission of unburned HC and preventing residual gas from staying in the auxiliary chamber, thus improving thermal efficiency in the high load region. Can be made.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a sub-chamber gas engine according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing an embodiment of a sub-chamber gas engine according to the present invention, and FIG. 4 is a diagram showing a valve timing of a sub-chamber opening / closing valve in the sub-chamber gas engine according to the present invention.

This sub-chamber type gas engine is driven by a diesel cycle using a gas fuel such as natural gas as a fuel. For example, a cylinder head 13 fixed to a cylinder block 24 is provided with intake and exhaust ports. The intake and exhaust ports are respectively provided with intake and exhaust valves. This sub-chamber type gas engine includes, for example, a cylinder head 13 and an intermediate head member 1 fixed to a cylinder block 24 via a gasket 27 and an intermediate head member 16.
6, a combustion chamber structure forming the main chamber 1 arranged in the cylindrical portion 17 formed in 6, and a cavity 8 formed in the cylinder head 13.
A sub-chamber structure 3, which forms the sub-chamber 2 of the heat shield structure arranged in
It has a piston 15 that reciprocates in a cylinder 14 formed by a cylinder liner 23. Cylinder head 13
A gasket 28 is arranged between the wall surface of the cavity 8 and the outer peripheral surface of the sub-chamber structure 3 formed at the same time, and the heat-shielding air layer 12 is formed so that the sub-chamber 2 has a heat-shielding structure. There is. The combustion chamber structure includes a headliner 10 in which a liner upper wall portion 31 and a liner side wall portion 32 are integrated. The gasket 26 is provided between the liner upper wall portion 31 of the headliner 10 and the lower surface of the cylinder head 13, and between the outer peripheral surface of the liner side wall portion 32 of the headliner 10 and the inner wall surface of the tubular portion 17 of the intermediate head member 16. And heat shield air layer 11
The main chamber 1 has a heat shield structure.

In this sub-chamber type gas engine, the sub-chamber structure 3 is arranged in the cavity 8 formed in the cylinder head 13 so that the sub-chamber 2 is formed substantially at the center of the cylinder shaft. The lower end portion of the sub chamber structure 3 protruding from the lower surface 33 of the cylinder head has a head liner 10 that constitutes the main chamber 1.
Fitting hole 30 formed substantially in the center of the head lower surface portion 31 of
Are located in A sub chamber opening / closing valve 4 for opening / closing the communication port 6 is arranged at the communication port 6 formed in the headliner 10. Further, in this sub-chamber type gas engine, the headliner 10 forming the main chamber 1 and the sub-chamber structure 3 forming the sub-chamber 2 are made of, for example, ceramics such as silicon nitride, silicon carbide, sialon, etc. having excellent heat resistance. It is made in. Further, since the sub-chamber structure 3 and the headliner 10 become hot, the sub-chamber on-off valve 4 arranged at the communication port 6 is made of a heat-resistant metal having high temperature strength and excellent in heat resistance, ceramics such as silicon nitride, silicon carbide or the like. It is manufactured.

The gas fuel from the gas fuel supply source 60 is transferred from the gas fuel passage 25 formed in the cylinder head 13 to the gas fuel passage by the valve body 51 of the gas fuel supply valve 5 opening the gas fuel supply port 22. The gas is supplied to the sub chamber upper portion 2A of the sub chamber 2 through the through hole 9A and the gas fuel supply port 22. A fuel supply source 60 containing natural gas as a fuel, that is, a gas fuel, is provided at an appropriate place, and the gas fuel from the fuel supply source 60 is sent to the gas fuel passage 25 through the fuel supply pipe 61.

The gas fuel of the gas fuel supply source 60 is pressurized to ⁵ to 7 kg / cm ² in, for example, a pressure boosting chamber, and the pressurized gas fuel is supplied through the fuel supply pipe 61 to the gas fuel supply passage 25. Is supplied to. Gas fuel supply valve 5
Is operated by an electromagnetic force by an electromagnetic drive unit which is unitized in the upper portion of the gas fuel supply valve 5 according to a command from the controller 70. When the gas fuel supply valve 5 operates in response to a command from the controller 70, the gas fuel is quickly supplied from the fuel supply pipe 61 through the gas fuel supply passage 25 through the gas fuel supply valve 5 into the sub chamber 2 at a low pressure. Further, for example, the pressure sensor 71 installed in the sub-chamber 2 detects that the gas fuel pressure in the sub-chamber 2 has reached the gas fuel pressure necessary for the load and the rotation speed of the engine, and outputs the detection signal. When the gas is supplied to the controller 70 and a predetermined amount of gas fuel is supplied to the sub chamber 2, the controller 70 issues a command to close the gas fuel supply valve 5, and the supply of gas fuel to the sub chamber 2 ends.

Further, in this sub-chamber type gas engine, in the controller 70, the gas fuel supply valve 5 supplies the sub-chamber 2 with an appropriate flow rate of the gas fuel corresponding to the engine load and the engine speed to improve fuel economy. At the same time, control for improving thermal efficiency can be performed. The controller 70 includes a load sensor 72 for detecting the engine load, a rotation sensor 73 for detecting the engine speed, a position sensor 74 for detecting the open / closed state of the sub chamber opening / closing valve 4, and a pressure sensor 71 for detecting the in-cylinder pressure of the sub chamber 2. And the like so that the flow rate of the gas fuel supplied into the sub chamber 2 becomes a preset fuel gas pressure that is optimum for the engine load and the engine speed based on these detection signals. The fuel supply valve 5 may be operated to supply the gas fuel to the sub chamber 2. In addition,
In this embodiment, the gas fuel supply valve 5 is configured to be operated by the electromagnetic drive device, but it may be operated by a valve operating device using a cam that operates in synchronization with engine rotation.

In this sub-chamber type gas engine, in particular, the sub-chamber structure 3 arranged substantially in the center of the cylinder is formed in a double structure, and the sub-chamber 2 has an inner structure 3A and an inner structure 3A. The outer structure 3B is arranged so as to surround the. A main communication port 7 is formed at the lower end of the inner structure 3A, and a sub communication passage 9 is formed in the gap between the inner structure 3A and the outer structure 3B. The main communication port 7 and the sub-communication passage 9 communicate with the communication port 6 formed at substantially the center of the head lower surface portion 31 of the head liner 10.
The sub communication passage 9 particularly extends from the lower end to the upper end of the sub chamber structure 3. The upper end opening of the sub communication passage 9 opens to the sub chamber upper portion 2A through the through hole 9A formed in the upper portion of the inner structure 3A.

Further, in this sub-chamber gas engine,
The sub chamber opening / closing valve 4 includes a first valve face 21 for opening / closing the communication port 6 and a second valve face 20 for opening / closing the main communication port 7.
And Further, the lower end opening of the sub communication passage 9 is opened between the first valve face 21 and the second valve face 20. Further, the first valve face 21 that opens and closes the communication port 6 has the head lower surface portion 31 of the head liner 10.
Contacting the lower end surface of the communication port 6 formed in the
Simultaneously with the lift of 1, the communication port 6 is separated and the communication port 6 is immediately opened. The second valve face 20 that opens and closes the main communication port 7 is fitted into the main communication port 7 of the inner structure 3A, and the sub chamber opening / closing valve 4 is lifted by a predetermined lift amount and then separated from the main communication port 7. Open the main communication port 7. Therefore, according to the valve lift amount of the sub-chamber on-off valve 4, as shown in FIG. 4, the sub-communicating passage 9 extends from the main communication port 7 until the sub-chamber opening / closing valve 4 reaches a predetermined lift amount L _1. Also, the passage area becomes wider, and the ignition and combustion in the sub chamber 2 progresses from the upper portion 2A of the sub chamber.

In this sub-chamber gas engine, first, when the valve lift of the sub-chamber opening / closing valve 4 is started, the first valve face 21 of the sub-chamber opening / closing valve 4 opens the communication port 6 and the sub-communication passage 9 communicates. It communicates with the mouth 6, whereby the compressed air from the main chamber 1 flows through the communication port 6 and the sub communication passage 9 into the sub chamber upper portion 2A from the through hole 9A of the inner structure 3A, as shown in FIG. At the same time, the effective channel area between the communication port 6 and the sub communication channel 9 gradually increases and reaches the maximum effective channel area S _F. When the compressed air flows into the sub chamber upper portion 2A, the sub chamber upper portion 2A
Ignition occurs at A and combustion is propagated toward the lower part 2B of the sub chamber.
Since the main communication port 7 in the meantime there is a gap between the auxiliary chamber off valve 4, the flow passage effective area M _C of the main communication port 7 will be communicated by a gap amount.

Next, the lift of the sub chamber on-off valve 4 is lifted by a predetermined amount L.
_1. For example, when the lift amount of 20 to 30% of the full lift amount is reached, the second valve face 20 starts to open the main communication port 7 and the effective flow passage area of the main communication port 7 is gradually increased. The compressed air from the main chamber 1 flows into the lower portion 2B of the sub chamber through the communication port 6 and the main communication port 7. Therefore, the production of the air-fuel mixture rapidly starts in the sub chamber lower part 2B, and the sub chamber on-off valve 4
Reach the full lift amount L _F , the maximum flow passage effective area M _F of the main communication port 7 is reached, and the primary combustion progresses in the rich mixture due to the combustion propagation from the upper portion 2A of the sub chamber, and NO _X
Suppress the occurrence of. Then, the pressure in the sub-chamber 2 rises, and the combustion gas of unburned air-fuel mixture or flame is jetted from the sub-chamber 2 to the main chamber through the main communication port, and the fresh air existing in the main chamber by the jetting energy. Are entrained to promote mixing, improve the air utilization rate, shorten the combustion period to complete the secondary combustion, suppress the generation of unburned HC and improve the thermal efficiency.

The sub-chamber gas engine is constructed as described above and is operated, for example, as follows. This sub-chamber gas engine is operated by sequentially repeating four strokes of an exhaust stroke, an intake stroke, a compression stroke and an expansion stroke, and when the sub-chamber on-off valve 4 starts to lift near the end of the compression stroke. First, the sub-chamber opening / closing valve 4 separates from the communication port 6 to open the communication port 6, and at the same time, the hot compressed air in the main chamber 1 passes through the sub-communication passage 9 from the through hole 9A to the sub-chamber upper part 2A. Inflow. The gas fuel supplied to the sub-chamber upper portion 2A immediately mixes with the gas fuel in the sub-chamber 2 immediately in the sub-chamber upper portion 2A and ignites and burns, and then the primary combustion is rapidly performed in the sub-chamber upper portion 2A and the sub-chamber 2 inside The pressure is increased, the process proceeds to the expansion stroke, and the unburned gas in the lower portion 2B of the sub chamber is pushed out so as to be ejected from the sub chamber 2 through the main communication port 7 to the main chamber 1 through the communication port 6.
The air present in the main chamber 1 is entrained by the jet energy of the unburned air-fuel mixture and flame from the sub chamber 2 to burn rapidly and completes the secondary combustion in a short time, causing the piston 15 to do work. The unburned gas is prevented from staying in the sub chamber 2,
Improves thermal efficiency.

Next, in the exhaust stroke, the exhaust valve opens the exhaust port, and at the beginning of the exhaust stroke, the main chamber 1 and the sub chamber 2
Exhaust gas inside is exhausted through the exhaust port, the sub chamber opening / closing valve 4 closes the communication port 6 during the exhaust stroke, and then the main chamber 1
The exhaust gas therein is exhausted through the exhaust port. When the sub chamber opening / closing valve 4 closes the communication port 6, the gas fuel supply valve 5 operates to open the gas fuel supply port 22, and the gas fuel is supplied to the sub chamber 2 through the gas fuel supply port 19. 2 is filled with a proper flow rate of gas fuel.

Next, in the intake stroke, the auxiliary chamber opening / closing valve 4 closes the communication port 6, the intake valve opens the intake port, and intake air is supplied to the main chamber 1. The sub chamber 2 is filled with a predetermined amount of gas fuel through the suction stroke and the compression stroke after the sub chamber opening / closing valve 4 closes the communication port 6. In the compression stroke, the intake valve closes the intake port, and the auxiliary chamber opening / closing valve 4 closes the communication port 6, so that the intake air supplied into the main chamber 1 is highly compressed to a high pressure. Next, when the sub chamber opening / closing valve 4 opens the communication port 6 near the end of the compression stroke, high temperature compressed air is introduced into the sub chamber upper portion 2A through the sub communication passage 9 and the through hole 9A. In this sub-chamber gas engine, the engine is driven by repeating the above cycle.

Next, another embodiment of this sub-chamber type gas engine will be described with reference to FIG. This embodiment has the same configuration and the same as the above embodiment except that the communication port 6 is formed in the sub chamber structure 3 and a large number of communication holes 29 are formed in the head lower surface portion 31 of the head liner 10. Since they have a function, the same reference numerals are given to the same parts and duplicate explanations are omitted. In this embodiment, the main chamber 1 is the cylinder head 1
It is composed of the headliner 10 of the combustion chamber structure arranged in the cylindrical portion 17 formed in 3. The sub-chamber structure 3 is arranged in a fitting hole 30 formed substantially in the center of the headliner 10, and the headliner 10 communicates with the communication port 6 formed in the sub-chamber structure 3 and is circumferentially spaced. Then, a plurality of communication holes 29 extending in the cylinder peripheral direction are formed. The sub-chamber opening / closing valve 4 is arranged in the communication port 6 of the sub-chamber structure 3.
In addition, a cavity 34 that forms a part of the main chamber 1 is formed in the piston 15.

Still another embodiment of the sub-chamber type gas engine will be described with reference to FIG. In this embodiment, the communication port 6 is formed in the sub chamber structure 3, and the main chamber 1 is the cylinder 1.
4 has the same configuration and the same function as the above embodiment except that the method of forming the sub-communication passage 9 in the sub-chamber structure 3 is different. And redundant description will be omitted. In this embodiment, the sub-chamber opening / closing valve 4 is arranged in the communication port 6 formed in the sub-chamber structure 3. The sub communication passage 9 is formed so as to extend from the lower end to the upper part of the sub chamber structure 3. The sub communication passage 9 can be formed as one or a plurality of passages.

[0030]

The sub-chamber gas engine according to the present invention is
As described above, the sub-chamber of the sub-chamber structure located substantially in the center of the cylinder and the main chamber on the cylinder side are communicated with each other through the communication port, and the sub-chamber opening / closing valve is used to open and close the communication port. A main communication port is provided at the lower end of the structure, a sub-communication passage extending from the lower end of the sub-chamber structure to an upper portion is provided, the sub-communication passage is opened to the upper part of the sub-chamber, and the sub-chamber opening / closing valve is opened at the time of valve lift. Since it is set to open the main communication port after opening the sub communication passage, first, compressed air flows in from the upper part of the sub chamber of the sub chamber and is ignited and burned in the upper part of the sub chamber. The unburned air-fuel mixture existing in the lower portion can be jetted into the main chamber in a state of being pushed out from the upper portion of the sub-chamber, and the unburned air-fuel mixture is prevented from remaining in the sub-chamber for a long period of time.

That is, in this sub-chamber type gas engine, since the unburned gas does not stay in the sub-chamber for a long period of time, it is possible to reduce the generation of unburned HC etc. and improve the thermal efficiency. There is no decrease in efficiency under high load.

Moreover, by supplying compressed air from the main chamber to the sub chamber, the gas fuel in the sub chamber uniformly and quickly produces a rich air-fuel mixture, and in the sub chamber, fuel rich with a large equivalence ratio is produced. suppressing generation of the NO _X at high speed primary combustion in a state. Then, unburned gas or combustion gas of flame is ejected from the sub-chamber into the main chamber through the main communication port, and fresh air in the main chamber is entrained by the ejected energy to rapidly perform secondary combustion in the main chamber. Progresses, the combustion period is shortened and combustion is completed. Further, in this sub-chamber gas engine, gas fuel is supplied to the sub-chamber with the communication port closed, and intake air supplied to the main chamber is compressed in the absence of gas fuel, Even if compressed air is highly compressed in the main chamber, self-ignition does not occur and knocking does not occur.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a sub-chamber gas engine according to the present invention.

FIG. 2 is a schematic sectional view showing another embodiment of the sub-chamber gas engine according to the present invention.

FIG. 3 is a schematic cross-sectional view showing another embodiment of the sub-chamber gas engine according to the present invention.

FIG. 4 is a diagram showing a valve timing of a sub chamber opening / closing valve in a sub chamber type gas engine according to the present invention.

[Explanation of symbols]

 1 Main chamber 2 Sub chamber 3 Sub chamber structure 4 Sub chamber opening / closing valve 5 Gas fuel supply valve 6 Communication port 7 Main communication port 8 Cavity 9 Sub communication passage 10 Headliner (combustion chamber structure) 13 Cylinder head 14 Cylinder 20th 2 valve face 21 first valve face 29 connecting hole 30 fitting hole

Claims (5)

[Claims] 1. A sub-chamber structure that is disposed in a cylinder head and forms a sub-chamber disposed substantially at the center of the cylinder, and the sub-chamber formed in the sub-chamber structure communicates with the main chamber on the cylinder side. Communication port, a sub-chamber opening / closing valve for opening and closing the communication port, a main communication port opened to the communication port and formed at a lower end of the sub-chamber structure, and the sub-chamber structure opening to the communication port A sub-communicating passage that extends from the lower end of the body to an upper portion of the sub-chamber, and a gas fuel supply valve that supplies gas fuel to the sub-chamber. A sub-chamber gas engine that is set to open the main communication port after opening. 2. The main chamber is composed of a combustion chamber structure arranged in a cavity formed in the cylinder head,
The sub-chamber structure is arranged in a fitting hole formed substantially in the center of the combustion chamber structure, the communication port is formed in the combustion chamber structure, and the sub-chamber opening / closing valve is provided in the combustion chamber structure. The sub-chamber gas engine according to claim 1, wherein the sub-chamber gas engine is disposed at the communication port. 3. The main chamber is composed of a combustion chamber structure arranged in a cavity formed in the cylinder head,
The sub-chamber structure is disposed in a fitting hole formed substantially in the center of the combustion chamber structure, the communication port is formed in the sub-chamber structure, and the combustion chamber structure communicates with the communication port. 2. The sub chamber according to claim 1, wherein a plurality of communication holes extending in the circumferential direction of the cylinder are formed so as to be spaced apart from each other in the circumferential direction, and the sub chamber opening / closing valve is arranged at the communication port of the sub chamber structure. Gas engine. 4. The main chamber is formed on the cylinder side,
The sub-chamber gas engine according to claim 1, wherein the communication port is formed in the sub-chamber structure, and the sub-chamber opening / closing valve is arranged in the communication port of the sub-chamber structure. 5. The sub chamber opening / closing valve has a first valve face for opening / closing the communication port and a second valve face for opening / closing the main communication port, and the first valve face is opened when the sub chamber opening / closing valve is lifted. The second valve face opens the main communication port after the valve face opens the communication port, and the auxiliary communication passage opens between the first valve face and the second valve face. The sub-chamber gas engine according to any one of 1 to 4.