JPH06101479A - Two-stroke gas engine - Google Patents

Abstract

PURPOSE:To provide by two-stroke gas engine which is designed to use natural gas, served to promote mixture of flame injected from an auxiliary chamber to a main chamber and air in the main chamber, as fuel. CONSTITUTION:A communicating hole 30 and a fuel inlet 23 are formed in an auxiliary chamber 2 arranged to a cylinder head 7 and gas fuel is fed to the auxiliary chamber 2 in a state to close the communicating hole 30 by a communicating hole valve 4. Further, in a state to close the communicating hole 30, intake air is fed through an intake air port 25 to a cylinder 18 to effect high compression thereof. Since gas fuel is not present in a main chamber 1 even when intake air is forced into a high compression state in the main chamber 1, gas fuel is prevented from self-ignition and knocking is prevented from occurring. The communicating hole 30 is released, compressed air is caused to flow in the auxiliary chamber 2 for ignition combustion and thereafter, an injection flame enlarged in an annular conical shape crosses a squish flow in the main chamber 1 to promote mixture and a combustion period is shortened to complete secondary combustion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supplies natural gas from a gas fuel supply source to a sub-chamber and supplies intake air to the main chamber in a state where communication with the sub-chamber is closed. The present invention relates to a two-stroke gas engine that mixes and burns gas fuel.

[0002]

2. Description of the Related Art Conventionally, an engine using natural gas as a main fuel has been developed as a cogeneration engine. In this cogeneration engine, power is taken out as electric energy by a generator, and heat of exhaust gas energy is heated by a heat exchanger to make hot water, which is used for hot water supply. It is expected that this cogeneration engine will be used as an urban electricity supply system in the future.

Examples of engines using natural gas as fuel include those disclosed in JP-A-54-156911 and JP-A-1-232119.

The internal combustion engine disclosed in Japanese Patent Laid-Open No. 54-156911 compresses intake air and supplies it to the main combustion chamber, and a part of the intake air is supplied into the jet cell ignition chamber.
The paraffinic hydrocarbon fuel is injected into the jet cell ignition chamber to produce a rich mixture, the intake air and the mixture are further compressed, and the paraffinic hydrocarbon fuel is injected into the main combustion chamber, while Further compressing the intake air and mixture to produce a lean mixture in the main combustion chamber, igniting the mixture in the jet cell ignition chamber before full compression of both mixtures is achieved producing a hot gas stream, the flow of the heat had gas was charged to the mixture in the main combustion chamber to ignite the mixture of the main combustion chamber, thereby reducing the production of NO _X.

Further, the engine for hydrogen / liquefied natural gas disclosed in JP-A-1-232119 supplies either one of hydrogen and liquefied natural gas as fuel in a low load operation state of the engine. A control means for supplying liquefied natural gas as fuel is provided in a high load operation state of the engine.

[0006]

However, in a gas engine that uses natural gas as fuel, since the fuel is a gas body, the fuel gas is sucked from the intake port by opening and closing the intake valve, and compressed, as with gasoline. Since it is ignited, the compression ratio cannot be increased and the theoretical thermal efficiency (η
= Work heat conversion / fuel heat quantity) is not necessarily high. The gas engine that is normally used has a compression ratio of about 9 to 13 and a theoretical thermal efficiency of only 48%.
When the gas engine is powered by electrical energy,
The net thermal efficiency is 34-35%, in some cases less than 30%. Therefore, as cooling water loss and exhaust gas energy, 65 to 70% of the fuel is released, and this heat energy is used for hot water supply by using a heat exchanger, and the hot water is too much. The current situation is that general equipment cannot be fully used.

Therefore, in the present situation, it is desired to improve the thermal efficiency when the electric energy is taken out from the gas engine. Gas engines are generally
It uses natural gas as fuel, and the fuel is gas. Therefore, when the gas is sucked in the suction stroke and then compressed, the temperature becomes high in the highly compressed state, and the phenomenon of self-ignition, that is, knocking occurs. Therefore, if the compression ratio of natural gas fuel is 12 or less,
It self-ignites. Also, regarding the thermal efficiency of the engine, it has been theoretically and experimentally confirmed that the thermal efficiency decreases as the compression ratio decreases. Therefore, the gas engine has a problem of how to increase the compression ratio while avoiding self-ignition of the gas fuel.

Further, since the natural gas is mainly used as the fuel for the gas engine, if an excellent engine capable of burning at a high compression ratio can be produced by using this natural gas, the natural gas which is said to exist infinitely exists. A gas engine for fuel can be completed.

Therefore, in the gas engine, in order to increase the compression ratio, the sub-chamber is filled with gas fuel and the compression top dead center TD is reached.
It is conceivable that a valve for opening and closing the communication hole is opened near C to communicate the sub chamber and the main chamber, and the highly compressed air in the main chamber and the gas fuel in the sub chamber are mixed and ignited. In this type of gas engine, good mixing of the gas fuel and air is a major problem.

Therefore, an object of the present invention is to solve the above-mentioned problems, and communication between the main chamber and the sub chamber is cut off by a communication hole, natural gas is introduced into the sub chamber, and the main chamber is inhaled. Only the air is compressed to increase the compression ratio, the communication hole valve of the communication hole is opened while the air in the main chamber is raised to a high temperature, and the highly compressed air in the main chamber flows into the sub chamber. Air and gas fuel are rapidly mixed in the sub-chamber due to the flow velocity of the air flowing in from the gap between the communication hole valve and the communication hole, but in this state the fuel equivalence ratio is large and the mixture is in a rich mixture state. The finished fuel becomes an expansion flame and is ejected from the communication hole into the main chamber, and the expansion flame mixes with the air in the main chamber, so the state of ejection of the flame from the sub-chamber to the air in the main chamber is improved. The shape of the main chamber is configured to achieve mixing and the flame is transferred from the sub chamber to the main chamber. Causes blown out air, to complete in a short time as much as possible uniform mixture was in secondary combustion promoting mixing of the squish flow to the main chamber and the flame, NO
2-stroke gas fueled with gas fuel that can reduce the generation of _X , HC, etc., especially improve thermal efficiency, prevent self-ignition of gas fuel to prevent knocking, and improve thermal efficiency as electric energy. To provide the engine.

[0011]

In order to achieve the above object, the present invention is configured as follows. That is,
The present invention relates to a cylinder block having a cylinder, a cylinder head fixed to the cylinder block, an intake / exhaust port provided in the lower portion of the cylinder, a piston reciprocating in the cylinder, a sub chamber formed in the cylinder head, A fuel passage formed in the cylinder head for supplying gas fuel from a gas fuel supply source to the sub chamber, a fuel valve for opening and closing a communication state between the fuel passage and the sub chamber, and an opening at the center of the lower surface of the head of the cylinder head. A communication hole that communicates between the sub chamber and the inside of the cylinder, a conical shape that is arranged in a valve seat provided in the communication hole, and a flame that is ejected from the sub chamber side to the cylinder side forms an expanded ring shape. A connecting hole valve having a valve face, and a shape that deepens from the central portion to the peripheral portion along the streamline pattern of the flame ejected from the sub chamber. Main chamber formed in the top surface of the piston,
A two-stroke gas engine having

Further, in this two-stroke gas engine, the communication hole valve opens near the compression top dead center to allow compressed air to flow into the sub chamber from the cylinder side, and the compressed air and the gas fuel inside the sub chamber. It is to ignite mixed with.

Further, in this two-stroke gas engine, the outer peripheral tip of the annular opening of the main chamber has a lip which is pointed radially inward in order to promote the squish flow to the main chamber near the end of the compression stroke. It is formed in.

[0014]

The two-stroke gas engine according to the present invention,
It is configured as described above and operates as follows. That is, this two-stroke gas engine includes a fuel valve that opens and closes a fuel passage to the sub chamber, and a communication hole valve that opens and closes a communication hole that communicates with the sub chamber that opens in the center of the lower surface of the cylinder head. Since the intake and exhaust ports are formed in the lower part of the cylinder, the compression ratio ε can be increased to about 18, the engine performance can be improved, and the rich air-fuel mixture can be combusted in the sub-chamber. The generation of _X can be suppressed. However, when using natural gas as the fuel, the gas is injected into the combustion chamber, resulting in diffusion combustion, but it causes self-ignition before the compression ratio reaches 18 and causes knocking, and burns with lean fuel. the occurrence of NO _X increases with.

Further, it is not necessary to form an intake / exhaust port in the cylinder head, the degree of freedom in designing the combustion chamber formed in the cylinder head is increased, and the sub chamber can be arranged in the center of the cylinder and formed in the piston head. The shape of the main chamber can be formed to match the flame emitted from the sub chamber. When the connecting hole is formed in the center of the lower surface of the head and the connecting hole valve is arranged in the connecting hole, the cylinder central region becomes a shadow of the connecting hole valve, and the combustion chamber is formed in the piston head corresponding to the cylinder central region. Is not valid either. Therefore, the shape of the main chamber formed in the piston head is such that, when the communication hole valve is formed in the conical valve face, the flame ejected from the sub chamber side to the cylinder side forms an expanded ring shape. The main chamber formed in the head is formed in a shape that becomes deeper from the central portion to the peripheral portion along the streamline pattern of the flame ejected from the sub chamber.

Therefore, in this two-stroke gas engine, gas fuel is supplied to the sub-chamber by a predetermined gas mass with the communication hole valve closed, while the intake air is introduced into the main chamber and the intake air is introduced into the main chamber. To compress independently. Since the gas fuel does not exist in the main chamber even if the intake air has a high compression ratio, the gas fuel does not self-ignite and knocking does not occur. Further, when the communication hole is opened, highly compressed intake air flows into the sub chamber from the main chamber due to the flow velocity of the air flowing in from the gap between the communication hole and the communication hole valve, so that the gas fuel and the compressed air are discharged. And are rapidly mixed and ignited. In this state, the fuel equivalent ratio is large, and the fuel-rich state is ignited and burned to suppress the generation of NO _X.

Next, the gas fuel, which has been mixed in the sub chamber, becomes an expansion flame and is ejected from the sub chamber through the communication hole into the main chamber and mixed with the fresh air existing in the main chamber. At this time, the clearance between the communication hole valve and the communication hole is a circular cross-section clearance, in other words, an annular conical clearance, and the flame ejected from the sub chamber to the main chamber through the annular conical clearance has an expanded ring shape. In addition, the main chamber formed on the top surface of the piston is formed in a shape that becomes deeper from the central portion to the peripheral portion along the streamline pattern of the flame ejected from the sub chamber,
As the clearance between the top surface of the piston and the lower surface of the head decreases, the squish flow that flows into the main chamber intersects with the expanding ring-shaped jet flame, and promotes mixing of air and flame. it can.

[0018]

Embodiments of the two-stroke gas engine according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of a two-stroke gas engine according to the present invention, and FIG. 2 is a sectional view showing an open state of a communication hole valve of the two-stroke gas engine of FIG.

This two-stroke gas engine is fitted into a cylinder block 14 having a scavenging port, that is, an intake port 25 and an exhaust port 31, a cylinder head 7 fixed to the cylinder block 14, and a hole 21 formed in the cylinder block 14. And the intake port 2 formed in the cylinder block 14 and the cylinder liner 6 that form the cylinder 18.
The cylinder liner 6 communicating with the scavenging port, that is, the intake port 20 and the exhaust port 31 formed in the cylinder liner 6 communicating with
A sub chamber wall 3 made of ceramics forming the sub chamber 2 arranged in the hole 19 formed in the cylinder head 7, a piston 15 reciprocating in the cylinder 18 formed in the cylinder liner 6. It has a main chamber 1 formed in the piston head 16 of the piston 15 and a communication hole 30 that connects the main chamber 1 and the sub chamber 2 to each other.

In this two-stroke gas engine,
A head liner 10 made of ceramics is fitted in the hole 9 formed in the cylinder head 7. The headliner 10 includes a liner upper portion 2 which constitutes a part of the cylinder 18.
8 and a head lower surface portion 11. A sub-chamber wall body 3 forming the sub-chamber 2 is integrally formed on the upper surface of the head lower surface portion 11. The sub chamber wall body 3 includes the cylinder head 7
It is composed of an upper wall body 12 and a lower wall body 13 fitted in the hole portion 19 of the above. The communication hole 30 is formed in the central portion of the cylinder of the head lower surface portion 11. The piston 15 includes a piston head 16 made of ceramics such as silicon nitride having excellent heat resistance, and a coupling ring 29 on the piston head 16.
Piston skirt 17 fixed by metal flow with
It consists of

In this two-stroke gas engine, natural gas as a gas fuel is passed through the fuel passage 8 to the sub chamber 2
It has a gas fuel supply source for supplying to. Although not shown, the gas fuel supply source has, for example, a fuel tank containing natural gas as a gas fuel and a pressure accumulating chamber for accumulating the natural gas from the fuel tank. Cylinder head 7 through 8
The fuel is supplied to the sub chamber 2 from the fuel inlet 23 formed in the above. Further, the two-stroke gas engine is arranged in the fuel valve 5 arranged at the fuel inlet 23 for adjusting the gas fuel supply to the sub chamber 2 and the communication hole 30 connecting the main chamber 1 and the sub chamber 2 with each other. It has a communication hole valve 4.

Further, in the area of the communication hole 30, the temperature of the combustion gas becomes high, and therefore the communication hole valve 4 arranged in the communication hole 30.
Is manufactured from ceramics such as silicon nitride and silicon carbide that have high temperature strength and excellent heat resistance. The fuel valve 5 has, for example, an electromagnetic valve drive device that is opened and closed by an electromagnetic force, and the valve opening period is determined according to the engine load. When the fuel valve 5 opens the fuel inlet 23, the gas fuel, which is a natural gas, is supplied from the pressure accumulating chamber to the sub chamber 2 in a required amount. Further, the two-stroke gas engine is provided with a turbocharger 22, and the exhaust gas discharged from the exhaust port 31 is sent to the turbine of the turbocharger 22. The turbine driven by the exhaust gas energy operates the compressor, and the air compressed by the compressor is supplied from the intake port 25 into the cylinder 18.

In particular, this two-stroke gas engine
The intake / exhaust ports 25, 31 are formed in the lower portion of the cylinder, and the main chamber formed in the piston head 16 has a degree of freedom to form the main chamber 1 having an ideal shape in the piston head 16 and the fuel passage 8 It is characterized in that it has a fuel valve 5 for opening and closing a communication state between the sub chamber 2 and the sub chamber 2, and a communication hole valve 4 arranged in a communication hole 30 for communicating the sub chamber 2 and the inside of the cylinder 18. The communication hole valve 4 is arranged in a valve seat 24 formed in a communication hole 30 opened in the center of the head lower surface portion 11 of the cylinder head 7, and is connected to the cylinder 18 from the sub chamber 2 side.
The flame ejecting to the side has a conical valve face which forms a flared ring shape 33. The main chamber 1 formed in the piston head 16 has a communication hole 30 from the sub chamber 2 side.
It is formed in a shape that becomes deeper from the central portion to the peripheral portion along the streamline pattern of the expanding ring-shaped jet flame that is ejected toward the cylinder 18 side through. Also, the piston head 16
A flat surface 27 is formed at the center of the contact hole 4 so as to serve as a relief when the communication hole valve 4 is opened and reduce a waste volume. The main chamber 1 is formed in a shape that becomes deeper from the peripheral edge of the flat surface 27 toward the peripheral side of the piston head 16. The outer peripheral edge of the main chamber 1 is formed with a pointed lip 34 so that the squish flow S generated by the air flow into the main chamber 1 through the gap 26 is favorably formed.

Further, in this two-stroke gas engine, the communication hole valve 4 is opened near the compression top dead center to allow compressed air to flow into the sub chamber 2 from the cylinder 18 side. It is for ignition by mixing with gas fuel.

In this two-stroke gas engine,
Headliner 10, which is a wall forming main chamber 1, sub-chamber 2
The upper wall body 12 and the lower wall body 13, the cylinder liner 6 and the piston head 16 which form the sub chamber wall body 3 forming the
For example, it is preferably made of ceramics such as silicon nitride and silicon carbide having excellent heat resistance. As a result, even if the gas temperature in the latter half of combustion becomes high, sufficient heat resistance,
It has high-temperature strength, emits less unburned hydrocarbons HC, etc., and can send the thermal energy generated in the sub chamber 2 and the main chamber 1 to the turbocharger 22. If the turbocharger 22 is provided with a generator / motor or an energy recovery device is provided downstream of the turbocharger 22, the thermal energy generated by this two-stroke gas engine can be reliably recovered and a gas engine with high thermal efficiency is provided. can do.

This two-stroke gas engine is constructed as described above and is operated as follows. This 2
The stroke gas engine is operated by performing four strokes of a scavenging / intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke with one rotation of the crankshaft, that is, two strokes of the piston 15, and sequentially repeating this. . First, in the intake stroke, intake air is supplied into the cylinder 18 from the intake port 25 formed in the lower portion of the cylinder, and the fuel valve 5 is opened with the communication hole 30 closed by the communication hole valve 4. Through the gas fuel supply source, the natural gas fuel gas is supplied to the sub chamber 2. At this time, since a small amount of exhaust gas remains after combustion in the sub chamber 2, when the gas fuel is introduced into the sub chamber 2, the gas fuel receives heat and is activated in the sub chamber 2.

In this two-stroke gas engine, in the compression stroke, the communication hole 30 is closed by the communication hole valve 4, and the intake air is highly compressed in the main chamber 1 to increase the compression ratio. Next, at the end of the compression stroke, that is, near the compression top dead center TDC, the communication hole valve 4 opens the communication hole 30, and through the communication hole 30, compressed air that has been compressed to a high temperature (for example, 650 ° C.) is passed from the main chamber 1 to the sub chamber. 2, the intake air is promoted to be mixed with the activated gas fuel to be ignited and burned, and the combustion proceeds rapidly to burn in a fuel rich state with reduced NO _X. Therefore, even if the intake air has a high compression ratio in the main chamber 1, since the gas fuel does not contain the gas fuel, the gas fuel does not self-ignite and knocking does not occur. Moreover, since the communication hole 30 is opened, highly compressed intake air flows into the sub chamber 2 from the main chamber 1 due to the flow velocity of the air flowing in from the gap between the communication hole 30 and the communication hole valve 4, and the gas fuel and the compressed air are compressed. And are rapidly mixed and ignited. In this state, the fuel equivalent ratio is large, and the fuel is rich in combustion and NO _x
Is suppressed.

Next, the gas fuel, which has been mixed in the sub chamber, is ignited and burned to form an expansion flame, which is ejected from the sub chamber 2 to the main chamber 1 through the communication hole 30 and the fresh air existing in the main chamber 1 is discharged. Mix with. At this time, the gap between the communication hole valve 4 and the communication hole 30 is a circular passage having a circular cross section, in other words, an annular conical passage, and the annular conical passage is a passage that expands toward the main chamber 1 side. The flame ejected from the sub-chamber 2 to the main chamber 1 through the sub-chamber 2 is blown in the expanding ring-like shape, and the main chamber 1 formed on the piston head 16 is
Since it is formed in a shape that becomes deeper from the central portion to the peripheral portion along the streamline pattern of the flame ejected from No. 6, it is mainly caused by a decrease in the gap 26 between the top surface of the piston head 16 and the head lower surface portion 11. The squish flow S flowing into the chamber 1 flows into the jet flame F having the expanding ring shape 33 so as to intersect with the jet flame F, and the mixing of the air and the jet flame in the main chamber 1 is promoted.

The flame in the sub chamber 2 is ejected to the main chamber 1 and shifts to the combustion process, that is, the expansion process, promotes mixing with the fresh air existing in the main chamber 1 and completes the secondary combustion in a short period of time. In this expansion process, the communication hole 30 is maintained in the open state and the sub chamber 2 to the main chamber 1
A flame is ejected to perform work, and the communication hole valve 4 is operated near the end of the exhaust stroke to close the communication hole 30.

As described above, this two-stroke gas engine is provided with the communication hole 30 and the fuel inlet 23 in the sub chamber 2 and stores the natural gas from the fuel tank in which the natural gas is stored in the pressure accumulating chamber. With the communication hole valve 4 closing the communication hole 30 of the natural gas, the control valve provided between the pressure accumulating chamber and the fuel passage 8 is opened to allow the gas fuel to flow from the fuel inlet 23 into the sub chamber 2 through the fuel passage 8. The intake air that is supplied and sucked into the main chamber 1 from the intake port 25 at the lower part of the cylinder is compressed in the upward compression stroke of the piston 15 while the communication hole 30 closes the communication hole 30 and is not supplied to the sub chamber 2. Therefore, even if the intake air is highly compressed in the main chamber 1, the gas fuel supplied into the sub chamber 2 is cut off from the main chamber 1 by the communication hole valve 4, so that it does not self-ignite. , Knocking There is no possibility to live.

Further, when the communication hole valve 4 opens the communication hole 30, highly compressed intake air flows into the sub chamber 2 from the main chamber 1 and the gas fuel and the intake air are mixed and ignited. High-speed combustion is performed in a fuel-rich state with a large ratio, and the generation of NO _X is suppressed. Furthermore, the sub-chamber 2 containing exhaust gas after combustion
Is introduced with a gas fuel from a gas fuel supply source, and the gas fuel receives heat in the sub chamber 2 and is activated. Also, this 2
In the stroke gas engine, if the fuel valve 5 is composed of an electromagnetically driven valve that is driven by electromagnetic force, the fuel valve 5 can be set to determine the valve opening period in response to the operating state of the engine load. An appropriate amount of gas fuel can be supplied to the sub chamber 2 according to the engine load.

[0032]

The two-stroke gas engine according to the present invention is constructed as described above and has the following effects. That is, this two-stroke gas engine includes a fuel valve that opens and closes a fuel passage to the sub chamber, and a communication hole valve that opens and closes a communication hole that communicates with the sub chamber that opens in the center of the lower surface of the cylinder head. Since the intake and exhaust ports are formed in the lower part of the cylinder and it is not necessary to form them in the cylinder head, the degree of freedom in designing the cylinder head is increased and it is possible to arrange an ideally shaped sub chamber in the center of the cylinder head. Therefore, the shape of the main chamber formed in the piston head can be formed to match the flame ejected from the sub chamber. That is, the main chamber formed in the piston head can be formed in a shape that becomes deeper from the central portion to the peripheral portion along the streamline pattern of the flame ejected from the sub chamber.

Therefore, the communication hole valve can be formed in the conical valve face so that the flame ejected from the sub chamber side to the cylinder side has an expanded ring shape. Then, the jet flame that expands into the expanded ring shape, that is, the annular cone shape, and the squish flow to the main chamber that occurs as the distance between the top surface of the piston head and the lower surface of the head in the compression stroke decreases. They can intersect to promote mixing of the air with the jet flame.

Moreover, since the intake air can be supplied to the main chamber and the gas fuel can be supplied to the sub-chamber while the communication hole valve closes the communication hole, self-ignition occurs even if the intake air is highly compressed in the main chamber. And no knocking occurs. Further, since the sub-chamber is compression-sealed in the absence of air and the mass of the gas fuel is increased and supplied to the sub-chamber, it is possible to control the fuel equivalence ratio to an appropriate value and improve the thermal efficiency. You can Further, a small amount of exhaust gas after combustion remains in the sub chamber, and when the gas fuel from the gas fuel supply source is introduced, the gas fuel receives heat and is activated in the sub chamber. Further, even if the intake air reaches a high compression pressure in the main chamber, the sub chamber is closed by the communication hole valve to shut off from the main chamber, and the activated gas fuel in the sub chamber self-ignites. Without, knocking does not occur.

Further, when the communication hole valve is actuated to open the communication hole, the air highly compressed and heated to a high temperature from the main chamber flows into the sub chamber all at once, and the gas fuel and the intake air are separated from each other. Mixing is accelerated at once and ignited, and in the sub-chamber, high-speed combustion is performed in a fuel-rich state with a large equivalence ratio.
The generation of _X is suppressed. Then, the pressure in the sub chamber rapidly rises due to the combustion, and the combustion is promoted, and at the same time, the flame blows from the sub chamber to the main chamber all at once through the communication hole, and the flame is fresh in the main chamber. Mixed with
The combustion is promoted to increase the combustion speed and complete the ideal secondary combustion. Therefore, this 2-stroke gas engine can greatly reduce the generation of NO _x , HC, etc., and if the combustion chambers of the main chamber and the sub chamber are made of ceramics, thermal energy is sufficient for the turbocharger and the energy recovery device. Therefore, a gas engine with high thermal efficiency can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a two-stroke gas engine according to the present invention.

FIG. 2 is a cross-sectional view illustrating a state when a communication hole valve of the two-stroke gas engine of FIG. 1 is opened.

[Explanation of symbols]

 1 Main chamber 2 Sub chamber 4 Communication hole valve 5 Fuel valve 7 Cylinder head 8 Fuel passage 11 Head lower surface part 14 Cylinder block 15 Piston 18 Cylinder 23 Fuel inlet 24 Valve seat 25 Intake port 30 Communication hole 31 Exhaust port

Claims (3)

[Claims] 1. A cylinder block in which a cylinder is formed,
A cylinder head fixed to the cylinder block, an intake / exhaust port provided in the lower portion of the cylinder, a piston reciprocating in the cylinder, a subchamber formed in the cylinder head, and a gas fuel from a gas fuel supply source in the subchamber. A fuel passage formed in the cylinder head, a fuel valve for opening and closing a communication state between the fuel passage and the sub chamber, and a communication between the sub chamber opened at the center of the lower surface of the head of the cylinder head and the inside of the cylinder. Communication hole, a communication hole valve having a conical valve face arranged in a valve seat provided in the communication hole and in which a flame ejected from the sub chamber side to the cylinder side forms an expanded ring shape, and the piston The piston has an annular opening on the top surface of the piston and has a shape that becomes deeper from the central side to the peripheral side along the streamline pattern of the flame ejected from the sub chamber. The formed main chamber, two-stroke gas engine having. 2. The communication hole valve opens near the compression top dead center to allow compressed air to flow into the sub chamber from the cylinder side, and to ignite the compressed air and gas fuel in the sub chamber. The two-stroke gas engine according to 1. 3. The outer peripheral tip of the annular opening of the main chamber is formed into a lip that is pointed radially inward in order to promote a squish flow to the main chamber near the end of the compression stroke. The two-stroke gas engine according to 1.