JPH06108874A - Six-stroke gas engine - Google Patents

Abstract

PURPOSE:To provide a six-stroke gas engine, with which high heat efficiency is achieved by using a gas fuel and by increasing the compression ratio, and by which self ignition is prevented. CONSTITUTION:A gas fuel chamber 2 is formed on a cylinder head 3, and a combustion chamber 1 and the gas fuel chamber 2 are communicated to one another by a connection hole 9, while an intake port 6, an exhaust port 7, and a fuel feeding port 8 are formed on the cylinder head 3. A fuel valve 11 provided on the fuel feeding port 8, is released during an fuel intake process, to feed a gas fuel to the combustion chamber 1. A connection hole valve 10 provided on the connection hole 9 is released during a fuel compression process, to accumulate the pressure of a compressed gas fuel in the gas fuel chamber 2. An inlet valve 12 provided on the inlet port 6 is released during an air intake process, to feed the intake air to the combustion chamber 1, and the air is highly compressed under a condition that no gas fuel exists. The exhaust gas in the combustion chamber 1 is exhausted by releasing an exhaust valve 13 provided on the exhaust port 7 during an exhausting stroke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a 6-stroke gas engine having a gas fuel chamber for accumulating gas fuel such as natural gas in a cylinder head.

[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. Then, this cogeneration engine is expected to be used as an urban electricity supply system.

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]

Generally, in a conventional gas engine that uses a gas such as natural gas as a fuel, the means for supplying the gas fuel to the combustion chamber in the cylinder supplies the gas fuel into the intake cylinder, The premixed gas is supplied into the cylinder, or a high-pressure gas fuel supply device is provided, and the gas fuel supply device injects the gas fuel into the cylinder near the compression top dead center TDC.

However, in a gas engine which supplies gas fuel into the intake cylinder and supplies it as a premixed gas into the cylinder,
To prevent knocking, the compression ratio cannot be set high, theoretical thermal efficiency (η = heat conversion of work / heat quantity of fuel) is low, and ignition plugs, glow plugs, etc. are required for ignition, ensuring durability. Is difficult. Further, the gas engine provided with the high-pressure gas fuel supply device requires a large scale of equipment and has the same problem with respect to the compression ratio as described above.

However, in a gas engine using natural gas as a fuel, since the fuel is a gas body, the fuel gas is sucked from the intake valve, compressed, and ignited in the same manner as gasoline, so the compression ratio should be increased. The theoretical thermal efficiency is not necessarily high. A gas engine that is normally used has a compression ratio of about 12 to 13 and a theoretical thermal efficiency of only 48%. When the gas engine is powered by electric energy, the thermal efficiency is 34 to 35%.
In some cases, the efficiency is 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. Therefore, it has been considered to improve the thermal efficiency by incorporating a heat shield type gas engine into the gas engine. The gas engine uses natural gas as fuel, and the fuel is gas. Therefore, when the gas is sucked in the suction stroke and then compressed, the compression becomes high and the temperature rises, and the phenomenon of self-ignition, that is, knocking occurs. However, the gas fuel of natural gas will self-ignite unless the compression ratio is 12 or less.
Regarding the thermal efficiency of the engine, there is a phenomenon that the thermal efficiency decreases when the compression ratio is small. Therefore, the gas engine has a problem of how to increase the compression ratio while avoiding self-ignition of the gas fuel.

Therefore, an object of the present invention is to solve the above-mentioned problems, and a gas fuel chamber is provided in the cylinder head without using a high-pressure gas supply device for highly compressing the gas fuel, and the gas fuel chamber is provided. Only the compressed gas fuel is temporarily stored in the engine, the intake air is highly compressed in the next cycle, and then the highly compressed intake air and the compressed gas fuel are mixed and ignited and burned to achieve a high compression ratio and high thermal efficiency. It is to provide a 6-stroke gas engine that achieves the above, prevents self-ignition of gas fuel to prevent knocking, reduces space, and enables weight reduction.

[0011]

In order to achieve the above object, the present invention is configured as follows. That is,
The present invention relates to a gas fuel chamber formed in a cylinder head, a combustion chamber formed on the cylinder side, a communication hole that connects the combustion chamber and the gas fuel chamber, an intake / exhaust port and a fuel supply port formed in the cylinder head, A fuel valve disposed in the fuel supply port for supplying gas fuel into the cylinder and opened during a fuel intake stroke, and a fuel valve disposed in the communication hole for accumulating compressed gas fuel in the gas fuel chamber. A communication hole valve that opens, an intake valve that is arranged in the intake port to supply intake air into the cylinder and that opens during an intake stroke, and an exhaust that is arranged in the exhaust port to discharge exhaust gas from the combustion chamber. It has an exhaust valve that opens during a stroke and is operated sequentially in 6 cycles of a fuel intake stroke, a fuel compression stroke, an intake stroke, an intake compression stroke, an expansion stroke and an exhaust stroke. About 6 stroke gas engine, wherein.

Further, in this 6-stroke gas engine, the gas fuel pressure at the fuel supply port is set to about 2 to 6 times the intake pressure at the intake port, and the gas fuel pressure is set at the top dead center of the intake compression stroke. Is set to a pressure higher than the intake pressure.

[0013]

The 6-stroke gas engine according to the present invention is
It is configured as described above and operates as follows. That is, this 6-stroke gas engine,
A fuel supply port for supplying gas fuel to a gas fuel chamber and a combustion chamber is sequentially formed in the cylinder head in six cycles of a fuel compression stroke, an intake stroke, an intake compression stroke, an expansion stroke and an exhaust stroke. Since the fuel valve which is opened during the fuel intake stroke is arranged in the communication hole, and the communication hole valve which is opened during the fuel compression stroke is arranged in the communication hole, it is possible to supply the gas fuel to the combustion chamber during the fuel intake stroke by opening the fuel valve. The gas fuel can be compressed in the fuel compression stroke and stored in the gas fuel chamber. Therefore, since the gas fuel can be compressed by the reciprocating motion of the piston, a high pressure gas fuel supply device or the like is unnecessary.
Next, since the intake air is introduced into the cylinder and compressed while the gas fuel is not present in the combustion chamber, self-ignition does not occur even if the intake air is highly compressed, and knocking does not occur. Therefore, this 6-stroke gas engine can have a high compression ratio, so that an engine with high thermal efficiency can be completed.

Further, in this 6-stroke gas engine, the gas fuel pressure at the fuel supply port is set to about 4 to 6 times the intake pressure at the intake port, and the gas fuel pressure is set at the top dead center of the intake compression stroke. Is set to a pressure higher than the intake pressure, for example, twice or more, so that the compressed gas fuel is surely ejected from the gas fuel chamber to the combustion chamber, the mixing of the gas fuel and air is promoted, and the ignition combustion is performed. To do.

In the gas engine, gas is used as fuel, but the gas fuel originally has a low ignition temperature and causes self-ignition. Therefore, in this 6-stroke gas engine, the gas fuel of about 2 to 6 atm accumulated in the pressure accumulating chamber or the like is compressed in a state where there is little air, and the compressed gas fuel is confined in the gas fuel chamber. Therefore, the work is stored in the piston as the gas fuel compressed in the gas fuel chamber, and the compressed gas fuel is ejected to the combustion chamber when the communication hole valve is opened, and the compression ratio is 18 to
The piston work for compressing the gas fuel does not become a negative work, that is, a waste work because it is ignited and burned by being mixed with compressed air compressed to about 20. Further, the intake air introduced into the combustion chamber from the intake port in the intake stroke has almost no gas fuel remaining in the combustion chamber, so that when the intake air enters, the gas fuel becomes thin immediately and residual gas fuel in the combustion chamber is reduced. It does not ignite and burn.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a 6-stroke gas engine according to the present invention will be described below with reference to the drawings. 1 to 6
Is an explanatory view showing each stroke of the 6-stroke gas engine, FIG. 1 is an explanatory view showing a fuel intake stroke in the 6-stroke gas engine, FIG. 2 is an explanatory view showing a fuel compression stroke in the 6-stroke gas engine, 3 is an explanatory view showing an intake stroke of the 6-stroke gas engine, FIG. 4 is an explanatory view showing an intake compression stroke of the 6-stroke gas engine, FIG. 5 is an explanatory view showing an expansion stroke of the 6-stroke gas engine, and FIG. 6 is an explanatory diagram showing an exhaust stroke in a 6-stroke gas engine. FIG. 7 is an explanatory diagram showing the valve timing of this 6-stroke gas engine.

This 6-stroke gas engine includes a cylinder block 4 forming a cylinder 5, a cylinder head 3 fixed to the cylinder block 4, a gas fuel chamber 2 formed in the cylinder head 3, and a combustion chamber formed in the cylinder 5. 1, a communication hole 9 that connects the combustion chamber 1 and the gas fuel chamber 2 to each other, an intake port 6 formed in the cylinder head 3, an exhaust port 7 and a fuel supply port 8, a piston 15 that reciprocates in the cylinder 5, and It has a coating rod 16 which converts the reciprocating motion of the piston 15 into the rotary motion of the crankshaft 14.

This 6-stroke gas engine is operated sequentially in 6 cycles of a fuel intake stroke, a fuel compression stroke, an intake stroke, an intake compression stroke, an expansion stroke and an exhaust stroke, and the piston 15 has six strokes, that is, a crankshaft. 14
Is completed in three rotations, among which power is generated in the expansion stroke to give a rotational force to the crankshaft 14.

Further, this 6-stroke gas engine is
The fuel valve 11 is arranged in the fuel supply port 8 for supplying the gas fuel to the combustion chamber 1 and is opened during the fuel intake stroke, and the piston 15 is arranged in the communication hole 9 for accumulating the compressed gas fuel in the gas fuel chamber 2 by the rise of the piston 15. And a communication hole valve 10 that is opened during the fuel compression stroke, an intake valve 12 that is arranged in the intake port 6 to supply intake air to the combustion chamber 1 and that is opened during the intake stroke, and exhaust gas from the combustion chamber 1 is discharged. It has an exhaust valve 13 arranged in the exhaust port 7 and opened during the exhaust stroke.
The fuel valve 11, the communication hole valve 10, the intake valve 12, and the exhaust valve 13 may be operated by a valve operating mechanism by a cam or an electromagnetic valve driving device driven by an electromagnetic force.

Further, in this 6-stroke gas engine, the gas fuel pressure in the fuel supply port 8 is set to be about 4 to 6 times as high as the intake pressure in the intake port 6, and the top dead of the intake compression stroke. At the point, the gas fuel pressure is set to be higher than the intake pressure. Therefore, when the communication hole valve 10 is actuated and the communication hole 9 is opened, the compressed gas fuel in the gas fuel chamber 2 is ejected into the combustion chamber 1 and ignition combustion can be performed in the combustion chamber 1. Although not shown, the gas fuel pressure can be easily adjusted to a desired pressure by, for example, accumulating the gas fuel from the gas fuel tank in the pressure accumulating chamber using a pressure pump. A 6-stroke gas engine does not require a high pressure gas supply.

This 6-stroke gas engine has the above-mentioned structure and operates as follows. This 6
In the stroke gas engine, after the exhaust stroke is completed, that is, after the exhaust stroke top dead center TDC, as shown in FIG. 1, the fuel intake stroke is entered and the piston 15 descends, but a negative pressure is generated in the cylinder. When the fuel valve 11 is operated to open the fuel supply port 8 to the combustion chamber 1, the gas fuel which is not so high in pressure from the gas fuel supply source is supplied to the combustion chamber 1 through the fuel supply port 8. The opening period of the fuel valve 11, that is, the valve timing can be set as shown in FIG. 7, for example. The piston 15 reaches the bottom dead center BDC to complete the fuel intake stroke, and then, as shown in FIG.
Starts to rise, and shifts to a fuel compression stroke in which the gas fuel supplied into the combustion chamber 1 is compressed.

In the fuel compression stroke, the communication hole valve 10 operates to open the communication hole 9, and the gas fuel in the combustion chamber 1 is introduced into the gas fuel chamber 2 while being compressed. The opening period of the communication hole valve 10, that is, the valve timing can be set as shown in FIG. 7, for example. At this time, even if the gas fuel in the combustion chamber 1 is compressed, since there is almost no air in the combustion chamber 1, it is compressed by unignition and becomes highly compressed gas fuel. Piston 1
5 reaches the top dead center TDC and the fuel compression stroke ends, but at this time, the communication hole valve 10 operates to close the communication hole 9. Therefore, most of the gas fuel existing in the combustion chamber 1 is highly compressed and accumulated in the gas fuel chamber 2.

Next, as shown in FIG.
Starts to descend and the intake stroke starts. At this time, the intake valve 12 is operated to open the intake port 8 and, for example, intake air sent from a turbocharger or the like is supplied to the combustion chamber 1. The opening period of the intake valve 12, that is, the valve timing can be set as shown in FIG. 7, for example. At this time, since the communication hole valve 12 closes the communication hole 9, gas fuel and intake air do not mix. The piston 15 reaches the bottom dead center BDC and the intake stroke ends, and then the piston 1
5 starts to rise and shifts to the intake compression stroke.

As shown in FIG. 4, in the intake compression stroke, all the valves, that is, the fuel valve 11, the communication hole valve 10, and the intake valve 12 are included.
Since the exhaust valve 13 and the exhaust valve 13 are closed, the intake air introduced into the combustion chamber 1 is highly compressed as the piston 15 rises, and the combustion chamber 1 contains gas fuel. Since no gas fuel is ignited and burned, a high compression ratio of the engine can be achieved. The piston 15 reaches the top dead center TDC, and the intake compression stroke ends.
At this time, the gas fuel pressure is set to be higher than the intake pressure at the top dead center of the intake stroke.

Then, as shown in FIG. 5, the combustion process, that is, the expansion process is started. From the vicinity of the top dead center TDC of the intake stroke to the beginning of the expansion stroke, the communication hole valve 10 operates to connect the communication hole 9
When is opened, the compressed gas fuel accumulated in the gas fuel chamber 2 is ejected into the combustion chamber 1 at a stroke, and the gas fuel is compressed in the combustion chamber 1 and becomes a high temperature and high pressure intake air at a stroke. It mixes, burns, burns, and does work. The opening period of the communication hole valve 10, that is, the valve timing can be set as shown in FIG. 7, for example. Also, the communication hole valve 10
The combustion timing can be controlled by controlling the valve timing of opening the valve.

In the expansion stroke, the combustion gas is the piston 1
The piston 15 reaches the bottom dead center BDC by working on 5,
The expansion stroke ends, and then the exhaust stroke is entered, as shown in FIG. In the exhaust stroke, the exhaust valve 13 operates to open the exhaust port 7, and exhaust gas is exhausted through the exhaust port 7. The opening period of the exhaust valve 13, that is, the valve timing can be set as shown in FIG. 7, for example. Although not shown, the exhaust gas discharged through the exhaust port 7 can be configured to recover the exhaust gas energy of the exhaust gas by a turbocharger, an energy recovery device, or the like.

Therefore, in this 6-stroke gas engine, in the intake compression stroke, the communication hole 9 is provided by the communication hole valve 10.
Can be closed and the intake air can be highly compressed in the combustion chamber 1 to increase the compression ratio. Next, at the end of the intake compression stroke, the communication hole valve 10 opens the communication hole 9, and the high pressure gas fuel in the gas fuel chamber 2 is highly compressed through the communication hole 9 and becomes high temperature (for example, 650 ° C.) compressed air. The existing fuel gas is jetted out into the existing combustion chamber 1 at once, and the jetted gas fuel promotes the mixing with the highly compressed intake air to be ignited and burned, and the combustion in the combustion chamber 1 is completed in a short period of time. Therefore, even if the intake air is highly compressed in the combustion chamber 1, the gas fuel supplied into the gas fuel chamber 2 is cut off from the combustion chamber 1 by the communication hole valve 10, so that self-ignition does not occur. No knocking will occur.

[0028]

The 6-stroke gas engine according to the present invention is constructed as described above and has the following effects. That is, in this 6-stroke gas engine, a cylinder head is provided with a gas fuel chamber and a fuel supply port for supplying gas fuel into the cylinder, and a fuel valve which is opened during a fuel intake stroke is arranged in the fuel supply port. A communication hole valve that opens during the fuel compression stroke is arranged in the hole, an intake valve that opens during the intake stroke is arranged in the intake port, and an exhaust valve that opens during the exhaust stroke is arranged in the exhaust port. The gas fuel can be supplied into the cylinder in the fuel intake stroke by opening the valve, and the gas fuel can be compressed in the fuel compression stroke to be stored in the gas fuel chamber, and the intake air can be stored in the cylinder with the gas fuel sealed in the gas fuel chamber. Can be introduced and compressed.

Therefore, since the gas fuel can be compressed by the reciprocating motion of the piston, even if the gas fuel is introduced into the cylinder at a low pressure without using a high pressure gas fuel supply device or the like, the gas fuel having a desired pressure can be obtained. Can be accumulated in. Therefore, since a high-pressure gas fuel supply device or the like is not required, the required space can be reduced, the engine can be made compact, and the weight of the engine can be reduced. Furthermore, since the intake air is introduced into the cylinder and compressed while the gas fuel is not present in the cylinder, self-ignition does not occur even if the intake air is highly compressed, and knocking does not occur.
Therefore, since this 6-stroke gas engine can achieve a high compression ratio, an engine with high thermal efficiency can be completed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a fuel intake stroke in a 6-stroke gas engine according to the present invention.

FIG. 2 is an explanatory view showing a fuel compression stroke of this 6-stroke gas engine.

FIG. 3 is an explanatory view showing the intake stroke of this 6-stroke gas engine.

FIG. 4 is an explanatory diagram showing the intake compression stroke of this 6-stroke gas engine.

FIG. 5 is an explanatory view showing the expansion stroke of this 6-stroke gas engine.

FIG. 6 is an explanatory diagram showing an exhaust stroke in this 6-stroke gas engine.

FIG. 7 is an explanatory diagram showing valve timing of this 6-stroke gas engine.

[Explanation of symbols]

 1 Combustion chamber (cylinder) 2 Gas fuel chamber 3 Cylinder head 4 Cylinder block 5 Cylinder 6 Intake port 7 Exhaust port 8 Gas fuel supply port 9 Communication hole 10 Communication hole valve 11 Fuel valve 12 Intake valve 13 Exhaust valve 15 Piston

Claims (2)

[Claims] 1. A gas fuel chamber formed in a cylinder head,
A combustion chamber formed on the cylinder side, a communication hole connecting the combustion chamber and the gas fuel chamber, an intake / exhaust port and a fuel supply port formed on the cylinder head, the fuel supply for supplying gas fuel into the cylinder A fuel valve arranged in the port for opening during a fuel intake stroke, a communication hole valve arranged in the communication hole for accumulating compressed gas fuel in the gas fuel chamber, for opening intake air in the cylinder An intake valve disposed in the intake port for supplying and opening during an intake stroke; and an exhaust valve disposed in the exhaust port for discharging exhaust gas in the combustion chamber, which opens during an exhaust stroke, and a fuel intake stroke A six-stroke gas engine which is sequentially operated in six cycles of a fuel compression stroke, an intake stroke, an intake compression stroke, an expansion stroke and an exhaust stroke. 2. The gas fuel pressure at the fuel supply port is set to about 2 to 6 times the intake pressure at the intake port, and the gas fuel pressure is higher than the intake pressure at the top dead center of the intake compression stroke. The 6-stroke gas engine according to claim 1, wherein the 6-stroke gas engine is set.