JPH1144227A - Structure of combustion chamber in engine - Google Patents

Abstract

[PROBLEMS] To reduce friction by accumulating a part of compressed air pressure in a main chamber as a spring force of a spring, and apply the spring force to a piston in an expansion stroke to use the work as work. To provide a structure of a combustion chamber in an engine that reduces fuel consumption. According to the present invention, a pressure adjusting ring and a spring are slidably inserted into an intake port, and a valve seat is formed on the pressure adjusting ring to seat an intake valve. During the compression stroke, the pressure adjusting ring 11 is slid by the compressed air in the main chamber 1 against the spring force of the spring 12 to reduce the air pressure in the main chamber 1. Next, the pressure adjusting ring 11 is moved to the spring 1 during the expansion stroke.
The work is returned by the spring force of No. 2 and the spring force of the spring 12 is applied to the piston 15 through the combustion gas to perform work.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a combustion chamber in an engine, and more particularly, to supplying gas fuel such as natural gas to a sub-chamber, supplying intake air to a main chamber, and near a top dead center of a compression stroke. The present invention relates to a structure of a combustion chamber that can be applied to a gas engine that mixes compressed air and gaseous fuel and ignites and burns.

[0002]

2. Description of the Related Art Conventionally, a gas engine using a gas fuel such as natural gas as a main fuel has been developed as a cogeneration system or an automobile engine. In the cogeneration system, engine torque is extracted as electric energy by a generator, and water is heated by a heat exchanger using heat energy of exhaust gas to make hot water, and the hot water is used for hot water supply. The cogeneration system is expected to be used as an electric supply system in hotels, hospitals, offices, and the like. When a gas engine is used for an automobile engine, it is expected to be a low-emission vehicle.

[0003] As a gas engine using natural gas or the like as a fuel, for example, there is one disclosed in Japanese Patent Application Laid-Open No. Hei 7-158448. In the gas engine, a sub-chamber formed in a cylinder head and a main chamber formed in a cylinder side communicate with each other through a communication hole, and a control valve is arranged in the communication hole. In addition, the gas chamber and the sub-chamber communicate with the head portion through a constricted portion, a gas inlet is formed in the gas chamber to supply natural gas to the sub-chamber through the gas passage, and a communication hole is formed near the end of the compression stroke. A control valve that opens is provided, and a gas introduction valve that opens when the communication hole is closed is provided at a gas introduction port formed in the gas chamber.

Conventional engines using natural gas as fuel are:
Since the ignitability is poor when the gas fuel is compressed and ignited, it is considered that the combustion chamber has a heat shielding structure. In a gas engine, if the combustion chamber is configured as a heat shield structure, the mixture of gas and air is sucked in during the suction stroke, and then compressed, the temperature inside the highly compressed cylinder increases, and the self-ignition phenomenon, ie, knocking, occurs. It is easy to occur. In addition, it has been theoretically clarified that the thermal efficiency of the engine decreases as the compression ratio decreases. Further, in the conventional engine, the gas fuel can be injected into the combustion chamber at a high pressure to perform the diesel combustion, thereby increasing the thermal efficiency. However, increasing the pressure in the combustion chamber and the fuel injection device increases the cost and increases the pressure. The problem that NO _X increases due to the injection occurs.

Therefore, in a gas engine, the combustion chamber is separated into a main chamber and a sub-chamber in order to send the gas fuel into the combustion chamber without excessively increasing the pressure of the gas fuel such as natural gas and perform diesel combustion. A control valve is disposed in a communication hole communicating the main chamber and the sub-chamber, gas fuel is supplied to the sub-chamber, air is introduced into the main chamber in a state where no gas fuel is present, and the air is compressed. Near the top dead center, gas fuel and compressed air are mixed and burned, enabling good operation.

[0006]

However, in the gas engine, the sub-chamber is arranged in the center of the cylinder, the control valve is arranged in the communication hole between the main chamber and the sub-chamber, and gas fuel is supplied to the sub-chamber. When the air is supplied to the main chamber and the control valve is opened near the top dead center of the compression stroke to mix the compressed air and gaseous fuel and ignite and burn, the communication hole is the crank angle before the top dead center of the compression stroke. If the control valve is opened at 25 ° or more, the ignition timing of the gas engine will be too early, and this will cause deterioration of fuel efficiency. If the opening time of the communication hole by the control valve is too late, the pressure of the main chamber until the opening of the communication hole increases, which increases the amount of work and reduces thermal efficiency.

Further, in the above gas engine, the control valve is operated in the latter half of the compression stroke to open the communication hole, and the main chamber and the sub-chamber are communicated. In this case, the compressed air pressure in the main chamber rises too much and the friction increases, and the compressed air flows from the main chamber to the sub-chamber near the top dead center of the compression stroke. Regardless, since the compressed air pressure drops sharply, the amount of work on the piston decreases, which leads to a corresponding decrease in fuel efficiency. Therefore, in a gas engine, if the air pressure compressed in the main chamber during the compression stroke can be stored without being consumed by friction, heat, etc., and the stored energy can be consumed as work by the piston during the expansion stroke, the thermal efficiency can be reduced. You can be up.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems. In order to prevent the pressure in the main chamber from becoming too large, a spring is provided at an intake port having little thermal influence. A pressure adjusting cylinder to which a force is applied is slidably disposed, and the pressure adjusting cylinder is slidably moved through an intake valve by air pressure compressed in the main chamber in a compression stroke to expand the volume of the main chamber; The air pressure in the main chamber is reduced, the excessive increase in the compressed air pressure in the main chamber is prevented to reduce the increase in friction during the compression stroke, and then the spring force accumulated in the spring during the expansion stroke is consumed to consume the main chamber. It is an object of the present invention to provide a structure of a combustion chamber in an engine in which the amount of work is returned to the combustion gas of the engine and the fuel efficiency is reduced and the thermal efficiency is improved.

According to the present invention, there is provided a combustion chamber member constituting a main chamber disposed in a cylinder head having a port formed therein, a piston reciprocating in a cylinder constituting the main chamber, and the port formed in the cylinder head. And an intake port opened and closed by an intake valve formed in the combustion chamber member and an exhaust port opened and closed by an exhaust valve, and a valve seat on which the intake valve is seated are formed and slide in the intake port. A pressure adjusting cylinder movably inserted therein, wherein the pressure adjusting cylinder is slid against the spring force of the spring by compressed air in the main chamber during a compression stroke to reduce the air pressure in the main chamber, thereby expanding the cylinder; The present invention relates to a structure of a combustion chamber in an engine, comprising returning the pressure adjusting cylinder by a spring force of the spring during a stroke.

The intake valve comprises a valve head seated on the valve seat of the pressure adjusting cylinder and a valve stem integral with the valve head. A valve stem is provided between an end of the valve stem and a cam for opening and closing the intake valve. Is provided with a head spring that expands and contracts according to the amount of movement of the intake valve by the pressure adjustment cylinder.

The spring is disposed between a flange provided on an outer surface of the pressure adjusting cylinder and a lower surface of the cylinder head. A seal ring for gas sealing is arranged on the outer periphery of the pressure adjusting cylinder, and a gap between the pressure adjusting cylinder and the intake port is sealed.

The structure of the combustion chamber in this engine is a sub-chamber member disposed in the cylinder head and having a sub-chamber communicating with the main chamber, and a fuel supply passage for supplying gaseous fuel to the sub-chamber. The present invention is applied to a gas engine having a control valve for opening and closing a communication port for communicating the main chamber and the sub chamber, and a fuel valve for opening and closing the fuel supply path for supplying gas fuel to the sub chamber. is there.

The control valve is set so as to open the communication hole near the end of the compression stroke and close the communication hole near the end of the exhaust stroke. The fuel valve opens when the communication hole is closed to open the fuel valve. The gaseous fuel is supplied to the sub-chamber from a supply path.

The sub-chamber is formed of a heat-shielding structure by the sub-chamber member made of ceramics or heat-resistant alloy. In addition, the main chamber is configured as a heat shielding structure by the combustion chamber member made of ceramics or heat-resistant alloy. Further, the pressure adjusting cylinder is made of ceramics made of Si ₃ N ₄ or SiC.

Since the structure of the combustion chamber in this engine is configured as described above, the pressure in the main chamber can be prevented from excessively increasing due to the presence of the pressure adjusting cylinder, and the compression of the pressure in the main chamber is reduced by the spring force of the spring pressing the pressure adjusting cylinder. The air pressure is accumulated, the friction consumed by the piston does not increase, and the spring force stored in the spring during the expansion stroke is consumed in the expansion stroke and returned as work, thereby improving the thermal efficiency. That is, it is possible to prevent the pressure in the main chamber from increasing excessively, to eliminate the peak pressure, and to eliminate the compression work indicated by the symbol A in FIG. Therefore, the present invention can improve the thermal efficiency as compared with the conventional engine.

The pressure adjusting cylinder is arranged at the intake port, but the intake port always cools the intake port area during the intake stroke because a large amount of intake air flows between the pressure adjusting cylinder and the intake valve. As a result, the sliding motion of the pressure adjusting cylinder is not adversely affected by heat, seizure does not occur, and the pressure adjusting cylinder can always operate smoothly. Even if the compressed air in the main chamber leaks to the intake port, the leaked compressed air is returned to the main chamber again,
There is no waste. During the compression stroke, no air is present in the sub-chamber, so that the gas fuel does not self-ignite and knocking does not occur. Can be compressed to air pressure.

The structure of the combustion chamber in this engine is such that the fuel valve is opened to supply gaseous fuel to the sub-chamber while the communication hole communicating the main chamber and the sub-chamber is closed by the control valve. The air introduced into the main chamber during the intake stroke is compressed during the compression stroke, and a part of the air is accumulated as the spring force of the spring that presses the pressure adjusting cylinder, preventing the compressed air pressure in the main chamber from rising too much as a whole. The increase in friction, heat, etc. is reduced, and the control valve is opened to introduce compressed air from the main chamber to the sub-chamber, where the compressed air and gaseous fuel are mixed and ignited in the sub-chamber, A gas such as a flame or an unburned mixture is blown into the chamber to cause the piston to work, and then, in an expansion stroke, the spring force of the spring is returned to the piston via the combustion gas as work to improve fuel efficiency.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the structure of a combustion chamber in an engine according to the present invention will be described below with reference to the drawings. The structure of the combustion chamber in this engine can be applied as a cogeneration system or an automobile engine. FIG. 1 is a sectional view showing an embodiment of the structure of a combustion chamber in an engine according to the present invention, and FIG. 2 is a diagram explaining the operation of the engine of FIG.

The gas engine incorporating the structure of the combustion chamber has a cylinder block 14, a cylinder head 7 mounted and fixed on the upper surface of the cylinder block 14 via a gasket 38, and a hole 3 formed in the cylinder block 14.
Cylinder liner 2 constituting cylinder 28 fitted to 7
7. Combustion chamber member 10 arranged in cavity 9 of cylinder head 7, Cylinder 2 formed in cylinder liner 27
8, a piston 15 reciprocating in the combustion chamber member 8,
And a sub-chamber member 3 for forming the sub-chamber 2 disposed in the cavity 6 formed in the cavity. The combustion chamber member 10 includes an intake valve 1
An intake port 20 in which an exhaust valve 8 is arranged and an exhaust port 30 in which an exhaust valve 16 is arranged are formed. The intake port 20 communicates with an intake port 19 formed in the cylinder head 7, and the exhaust port 30 communicates with an exhaust port 17 formed in the cylinder head 7. The main chamber 1 is a combustion chamber member 1
It is formed by a region surrounded by the cylinder 28 formed at 0, the cylinder 28 formed by the cylinder liner 27, and the top surface 35 of the piston 15.

The combustion chamber member 10 arranged in the cavity 9 of the cylinder head 7 comprises a head liner composed of a head lower surface 46 and a liner upper 47 integrally formed with the head lower surface 46. On the lower surface 46 of the head,
An intake port 20 and an exhaust port 30 are formed, and an intake valve 18 is disposed in the intake port 20.
At 0, an exhaust valve 16 is arranged. The sub-chamber member 3 arranged on the head lower surface portion 46 of the combustion chamber member 10 includes the main chamber 1
A communication hole 13 that communicates with the sub-chamber 2 is formed. The sub-chamber member 3 is formed with a valve seat 31 on which the control valve 4 is seated for opening and closing the communication hole 13 between the main chamber 1 and the sub-chamber 2.

The combustion chamber member 10 is made of a heat-resistant material such as a ceramic such as Si ₃ N ₄ or a heat-resistant alloy, and has a heat shield between the outer peripheral surface of the combustion chamber member 10 and the cavity 9 formed in the cylinder head 7. The main chamber 1 is configured as a heat shield structure, and is disposed in the cavity 9 of the cylinder head 7 with a gasket 34 interposed therebetween so as to form an air layer 36. Furthermore,
The sub-chamber member 3 is formed of a heat-resistant material such as ceramics such as Si ₃ N ₄ or a heat-resistant alloy, and a gasket 33 is interposed between the sub-chamber member 3 and the cavity 6 formed in the combustion chamber member 10 so as to form a heat shielding air layer 39. The sub-chamber 2 is arranged in the cavity 6 of the combustion chamber member 10 and has a heat-shielding structure.

The piston 15 includes a piston head 25 formed of a heat-resistant material such as ceramics such as Si ₃ N ₄ or a heat-resistant alloy, and a piston skirt fixed to the piston head 25 formed of a metal material such as an Al alloy. 26. A gasket 41 is interposed between the piston head 25 and the piston skirt 26 to form a heat shield air layer 44, and the piston head 25 and the piston skirt 26 are fixed by a connecting ring 29 by metal flow or the like.

In this gas engine, the control valve 4 is disposed in the communication hole 13 formed in the sub-chamber member 3 through the insertion hole 32 formed in the cylinder head 7 and the sub-chamber member 3. Further, in order to supply gas fuel to the sub-chamber 2 through the gas fuel supply passage 8 formed in the cylinder head 7,
The sub-chamber member 3 has a gas fuel inlet in which the fuel valve 5 is arranged. The control valve 4 reciprocates to open the communication hole 13 near the end of the compression stroke, to make the sub chamber 2 and the main chamber 1 in communication, and to close at the end of the exhaust stroke at the latest to close the main chamber 1 and the sub chamber 2. It is set to operate so as to shut off. The fuel valve 5 is set so as to open when the communication hole 13 is closed and supply gaseous fuel from the fuel supply passage 8 to the sub-chamber 2. The fuel valve 5 is operated so as to open the gas fuel inlet when the control valve 4 closes the communication hole 13. Therefore, when the fuel valve 5 opens the gas fuel inlet from the intake stroke to the compression stroke, the gas fuel is supplied to the sub-chamber 2 through the gas fuel supply passage 8.

The structure of the combustion chamber in this engine is, in particular, a pressure adjusting cylinder in which a valve seat 51 on which the intake valve 18 is seated is formed and which is slidably inserted into an intake port 20 formed in the combustion chamber member 10. 11 and pressure adjusting cylinder 1
It is characterized in that it has a spring 12 which presses the lower part 1. The spring 12 is disposed between a flange portion 48 provided on the outer surface of the pressure adjusting cylinder 11 and the lower surface of the cylinder head 7. Pressure adjusting cylinder 11
Is slidably disposed in the intake port 20, and the gap between the outer surface of the pressure adjusting cylinder 11 and the inner surface of the intake port 20 is sealed by a seal ring 50. Pressure adjusting cylinder 1
Reference numeral 1 denotes the volume of the main chamber 1 which is slid upward by the compressed air in the main chamber 1 against the spring force of the spring 12 during the compression stroke, so that the pressure adjusting cylinder 11 is pushed into the intake port 20. Is expanded, and the air pressure in the main chamber 1 is reduced. Next, during the expansion stroke, the pressure adjusting cylinder 11 causes the spring 1 to fall due to a decrease in the combustion gas pressure in the main chamber 1.
It is returned downward by the spring force of 2.

The intake valve 18 and the exhaust valve 16 are connected to a valve head 42.
And a valve stem 43 integral with the valve head 42. The intake valve 18 and the exhaust valve 16 are biased in a direction to close the intake port 20 and the exhaust port 30 by a return spring 40 disposed between the valve seat 24 fixed to the valve stem 43 by a cotter and the cylinder head 7. Have been. The intake valve 18 is driven by a cam 22 of the valve operating mechanism, and the exhaust valve 16 is driven by a cam 49 of the valve operating mechanism.

Further, the valve head 42 of the intake valve 18 is configured to be seated on the valve seat 51 of the pressure adjusting cylinder 11. Between the end of the valve stem 43 and the cam 22 that drives the intake valve 18 to open and close, a head spring 21 that expands and contracts according to the amount of movement of the intake valve 18 by the pressure adjusting cylinder 11 via a tappet 23 is interposed. I have.

In this gas engine, the spring 12 is compressed by the compressed air pressure of the main chamber 1 during the compression stroke of the piston 15.
The pressure adjusting cylinder 11 is slid upward to oppose the spring force to expand the volume of the main chamber 1 to depressurize the main chamber 1, and then the spring force accumulated in the spring 12 during the expansion stroke of the piston 15. The configuration is such that the pressure adjusting cylinder 11 is pushed down to cause the piston 15 to work through the combustion gas. The pressure adjusting cylinder 11 is made of Si ₃ N ₄
A seal ring 50 seals the space between the wall surface of the intake port 20 and the outer peripheral surface of the pressure adjusting cylinder 11.
Backflow of compressed air to 0,19 is prevented.

The gas fuel of natural gas is accommodated in a gas fuel supply source such as a gas fuel tank or a gas fuel accumulator (not shown) for accumulating gas fuel. Since the temperature of the communication hole 13 becomes high due to the combustion gas, the control valve 4 disposed in the communication hole 13 is preferably made of ceramics such as silicon nitride and silicon carbide having high temperature strength and excellent heat resistance. The fuel valve 5 may be operated by a normal valve operating mechanism, but is configured to be operated by an electromagnetic valve driving device 45 that is opened and closed by an electromagnetic force, and the valve opening period of the fuel valve 5 is controlled according to the engine load. May be configured to be controlled.
The fuel valve 5 is configured to introduce a required amount of gas fuel from the gas fuel supply source into the sub-chamber 2 by opening the gas inlet.

Next, the operation of the engine having the combustion chamber structure according to the present invention will be described with reference to FIG. This gas engine is operated by sequentially repeating four strokes of an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke. First, in the intake stroke, the intake valve 18 opens the intake ports 19 and 20. When the intake air is supplied to the main chamber 1 and the control valve 4 closes the communication hole 13, the fuel valve 5
Opens the gas fuel supply passage 8, and gas fuel is supplied to the sub chamber 2 from the gas fuel inlet through the gas fuel supply passage 8.
At this time, since the combustion gas after combustion slightly remains 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.

Next, the engine shifts to a compression stroke. In the compression stroke, the communication hole 13 is closed by the control valve 4, and the intake air in the main chamber 1 is compressed as the piston 15 rises. As the compressed air pressure rises as indicated by the line N, the compressed air pressure N in the main chamber 1 slides and moves the pressure adjusting cylinder 11 upward against the spring force of the spring 12, and the volume in the main chamber 1 increases. Then, the compressed air pressure is reduced. For comparison with a conventional gas engine which does not have a pressure adjusting cylinder, the compressed air pressure in the main chamber of the conventional gas engine is indicated by the symbol M. Thereafter, as a spring force of the spring 12 pushed up by the pressure adjusting cylinder 11, the compressed air is accumulated in a state where a part of the compressed air pressure is maintained. Is further compressed according to During the compression stroke, the gas fuel in the sub-chamber 2 is activated and a slight pressure rise occurs, as shown in the line S.

Next, when the piston 15 further rises and reaches the vicinity of the end of the compression stroke in which the compressed air in the main chamber 1 is compressed (reference OP), the control valve 4 opens the communication hole 13 and the communication hole 13 is opened. High temperature (eg, 650 ° C) compressed through
The compressed air flows into the sub-chamber 2 from the main chamber 1, and the main chamber 1 is depressurized at once and the pressure in the sub-chamber 2 is rapidly increased. The compressed air introduced into the sub-chamber 2 is mixed with the gaseous fuel and reliably ignites and burns, and the inside of the sub-chamber 2 has the maximum pressure Smax.
Reach The state at the time of general rapid combustion is shown by a dotted curve for reference. Since this gas engine is provided with the pressure adjusting cylinder 11 and the spring 12, the pressure line M of the main chamber 1 is smaller than the pressure line M of the main chamber without the pressure adjusting cylinder 11 and the spring 12. As a result, the pressure can be suppressed to a low level by the amount of energy stored in the area, and the friction and heat are not consumed in the area indicated by the oblique line A.

The ignition combustion in the sub-chamber 2 propagates the flame, and the combustion of the activated air-fuel mixture in the sub-chamber 2 proceeds smoothly.
Combustion in the auxiliary chamber 2 is burned in a state of reduced NO _X in rapid progress to fuel-rich. Next, the process proceeds to the expansion stroke, and gases such as the flame in the sub-chamber 2 and the unburned air-fuel mixture are blown out to the main chamber 1 through the communication hole 13 to entrain the air existing in the main chamber 1 to promote combustion, and the piston 15 works and the pressure in the main chamber 1 drops according to line NE. At this time, the pressure adjusting cylinder 11 is slid downward by the spring force of the spring 12, and the spring force accumulated in the spring 12 acts on the piston 15 to perform work. For comparison with a conventional gas engine without a pressure adjusting cylinder, the compressed air pressure of the main chamber during the expansion stroke of the conventional gas engine is indicated by the symbol ME. Therefore, this gas engine
The pressure line ME of the main chamber without the pressure adjusting cylinder 11
, The work in the area indicated by the oblique line B increases.

As described above, in the engine having the combustion chamber structure according to the present invention, a part of the compressed air pressure in the main chamber 1 is temporarily accumulated as the spring force of the spring 12 in the compression stroke, and Is not compressed, the compressed air pressure in the main chamber 1 can be kept low, energy is not consumed for friction, heat, etc. in the area indicated by the oblique line A, and the spring 12 is not compressed during the expansion stroke.
Compressed air accumulated as the spring force of
Since the fuel gas is returned to the combustion gas again with the spring force of 2, the thermal efficiency in the region indicated by the oblique line B can be improved and the fuel efficiency can be reduced. In this engine, a communication hole 13 and a gas fuel inlet are provided in the sub-chamber 2, and the gas fuel from the gas fuel supply source is supplied to the sub-chamber 2 through the gas fuel supply passage 8 with the communication hole 13 closed by the control valve 4. In addition to the supply to the chamber 2, the intake air sucked from the intake ports 19 and 20 into the main chamber 1 is closed by the control valve 4 so that the communication hole 13 is closed and the intake air is not supplied to the sub-chamber 2.
5, the gas fuel supplied into the sub-chamber 2 is shut off from the main chamber 1 by the control valve 4 even if the intake air is highly compressed in the main chamber 1. Therefore, the gas fuel does not self-ignite and knocking does not occur. Further, when the control valve 4 opens the communication hole 13, the intake air with a high compression ratio flows from the main chamber 1 into the sub-chamber 2, where the fuel gas and the intake air are mixed and ignited, and the equivalence ratio is large. NO _X and fast burning fuel-rich conditions, the generation of HC and the like can be suppressed.

Next, another embodiment of the structure of the combustion chamber in the engine according to the present invention will be described with reference to FIG.
This embodiment has the same structure as the above embodiment except that the sub-chamber 2 is not provided. Therefore, the same reference numerals are given to the same parts, and the duplicate description will be omitted. This type of combustion chamber structure uses, for example, a direct injection diesel engine or gasoline engine in which fuel is directly supplied to the main chamber 1 by a fuel injection nozzle or the like, or a high-pressure fuel injection nozzle having no sub chamber. The present invention can be applied to a gas engine that supplies gas fuel to a combustion chamber.

[0035]

As described above, the structure of the combustion chamber in the engine according to the present invention is such that the pressure adjusting cylinder and the spring are provided at the intake port and a part of the compressed air pressure is accumulated as the spring force of the spring during the compression stroke. In the expansion stroke, the spring force of the spring is returned to the work of the piston, which prevents the compressed air pressure in the main chamber from rising abnormally.
The amount of work during the compression stroke does not increase, and the pressure of the main chamber does not become too large, so that the durability of the combustion chamber member is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment in which the structure of a combustion chamber in an engine according to the present invention is applied to a gas engine.

FIG. 2 is a diagram illustrating the operation of the gas engine of FIG. 1;

FIG. 3 is a sectional view showing another embodiment of the structure of the combustion chamber in the engine according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main chamber 2 Sub chamber 3 Sub chamber member 4 Control valve 5 Fuel valve 6, 9 Cavity 7 Cylinder head 8 Fuel supply path 10 Combustion chamber member 11 Pressure adjustment cylinder 12 Spring 13 Communication hole 15 Piston 16 Exhaust valve 17, 30 Exhaust port 18 Intake valve 19, 20 Intake port 21 Head spring 22 Cam 28 Cylinder 31, 51 Valve seat 42 Valve head 43 Valve stem 50 Seal ring

Claims (9)

[Claims] 1. A combustion chamber member constituting a main chamber disposed in a cylinder head having a port formed therein, a piston reciprocating in a cylinder constituting the main chamber, and a port formed in the cylinder head, respectively. An intake port communicated with and opened and closed by an intake valve formed in the combustion chamber member, an exhaust port opened and closed by an exhaust valve, and a valve seat on which the intake valve is openably and closably formed are formed in the intake port. A pressure adjusting cylinder slidably inserted therein, wherein the pressure adjusting cylinder is slid against the spring force of a spring by compressed air in the main chamber during a compression stroke to increase the volume of the main chamber. A structure of a combustion chamber in an engine, comprising reducing air pressure in the main chamber and returning the pressure adjusting cylinder by a spring force of the spring during an expansion stroke. 2. The intake valve comprises a valve head seated on the valve seat of the pressure adjusting cylinder, and a valve stem integral with the valve head. An end of the valve stem and a cam for opening and closing the intake valve are provided. 2. The structure of a combustion chamber in an engine according to claim 1, wherein a head spring that expands and contracts in accordance with the amount of movement of the intake valve by the pressure adjusting cylinder is interposed between the two. 3. The structure of a combustion chamber in an engine according to claim 1, wherein said spring is disposed between a flange provided on an outer surface of said pressure adjusting cylinder and a lower surface of said cylinder head. 4. A sub-chamber member disposed in the combustion chamber member and formed with a sub-chamber communicating with the main chamber, a fuel supply passage for supplying gaseous fuel to the sub-chamber, the main chamber and the sub-chamber. 2. The engine according to claim 1, wherein the engine is applied to a gas engine having a control valve for opening and closing a communication port communicating with a sub-chamber, and a fuel valve for opening and closing the fuel supply path for supplying gas fuel to the sub-chamber. Combustion chamber structure. 5. The control valve is configured to open the communication hole near the end of the compression stroke and close the communication hole near the end of the exhaust stroke, and to open the fuel valve when the communication hole is closed. 5. The structure of a combustion chamber in an engine according to claim 4, comprising supplying the gaseous fuel to the sub-chamber from the fuel supply passage. 6. The sub-chamber is constituted by a sub-chamber member made of ceramics or a heat-resistant alloy to form a heat shielding structure.
Or a structure of a combustion chamber in the engine according to 5. 7. The structure of a combustion chamber in an engine according to claim 1, wherein the main chamber is formed of a heat shielding structure by the combustion chamber member made of ceramics or a heat-resistant alloy. 8. The pressure adjusting cylinder is made of Si ₃ N ₄ or Si ₃ N _4.
The structure of the combustion chamber in the engine according to claim 1, wherein the combustion chamber is made of ceramics made of C. 9. The combustion in the engine according to claim 1, wherein a seal ring for gas sealing is arranged on an outer periphery of the pressure adjusting cylinder, and a gap between the pressure adjusting cylinder and an intake port is sealed. The structure of the room.