JPH084562A - Multi-fuel engine - Google Patents

Abstract

(57) [Summary] [Objective] This multi-fuel engine is configured so that the fuel supply of natural gas or liquid fuel can be switched, and is driven by gas fuel during normal operation and by liquid fuel during emergency operation. [Structure] In this multi-fuel engine, a main chamber 1 and a sub chamber 2 communicate with each other through a communication hole 9, and a sub chamber 2 and a gas chamber 6 communicate with each other through a through hole 7. The gas fuel supply valve 5 opens and closes the gas inlet 26, and the sub chamber control valve 4 opens and closes the through hole 7. A fuel injection nozzle 3 for supplying liquid fuel is provided in the sub chamber. The controller 10 deactivates the fuel injection nozzle 3 during normal operation and opens and closes the sub-chamber control valve 4 and the gas fuel supply valve 5 to drive the engine with gas fuel. Control is performed to maintain the gas fuel supply valve 5 closed and to inject the liquid fuel from the fuel injection nozzle 3 into the sub chamber 2 to drive the engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-fuel engine which can be operated with either natural gas fuel or liquid fuel.

[0002]

2. Description of the Related Art Conventionally, a natural gas, that is, a gas engine using natural gas as a main fuel has been developed as a cogeneration engine or an automobile 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. The cogeneration engine is expected to be used as an electricity supply system in hotels, hospitals, offices and the like. Further, when a natural gas engine is used as an automobile engine, it is expected to be a low-pollution vehicle.

Further, Japanese Laid-Open Patent Publication No. 1-104930 discloses a multi-fuel engine. The multi-fuel engine is a combustion chamber to which air and gas fuel or air and liquid fuel are supplied,
An ignition plug for igniting a mixed gas of air and a gaseous fuel, a liquid fuel injection valve for injecting a liquid fuel into the combustion chamber are provided, and it is configured to be able to switch between a gas fuel operation and a liquid fuel operation. , The spark plug is arranged in the center of the cylinder head, the liquid fuel injection valve is arranged on the side of the cylinder, and the combustion ratio of the engine is set to a value suitable for the liquid fuel by lean-burning the gaseous fuel. Is.

Further, Japanese Patent Laid-Open No. 63-5152 discloses L
A PG fuel supply control device is disclosed. The LPG fuel supply control device includes a gas-phase fuel supply means, an operating state detection means, and an internal combustion engine fuel control means, and a liquid-phase fuel supply means for directly supplying the LPG fuel in a liquid phase state to a fuel chamber of the internal combustion engine. The internal combustion engine fuel control means is provided with liquid phase fuel control means for controlling the liquid phase fuel supply means based on the operating state of the internal combustion engine detected by the operating state detecting means. Further, the LPG fuel supply control device controls the liquid phase fuel supply means by the liquid phase fuel control means to control the internal combustion engine by the liquid phase fuel control means when the load or the rotational speed of the internal combustion engine detected by the operating state detection means is larger than a predetermined value. LPG fuel to be supplied to the LPG fuel in the liquid phase from the LPG fuel in the gas phase
It switches to G fuel.

[0005]

However, the conventional general gas engine that uses natural gas as a fuel is
Since the fuel is a gas, the fuel gas is sucked in from the intake valve, compressed, and ignited in the same way as gasoline,
The compression ratio cannot be increased, and the theoretical thermal efficiency (η = heat conversion of work / heat quantity of fuel) is not necessarily high. Therefore, at present, it is desired to improve the thermal efficiency of 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 natural gas engine uses natural gas as fuel, and the fuel is gas. Therefore, in a natural gas engine, when a mixture of gas and air is sucked in the intake stroke and then compressed, the compression becomes high and the temperature rises, causing a phenomenon of self-ignition, that is, knocking.
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.

In the conventional gas engine, the high pressure air in the latter half of the compression stroke is supplied into the sub chamber to rapidly and uniformly mix it to realize the primary combustion, and then the main chamber by the gas jet flow from the sub chamber to the main chamber. It is intended to realize lean combustion and is used as a cogeneration gas engine to obtain electric power and hot water. However, in a natural gas engine, the amount of gas to the sub chamber is reduced at the time of partial load. Therefore, if the natural gas supplied to the sub chamber is dispersed in the sub chamber, the sub chamber becomes a gas fuel that is too lean. It becomes a mixture of air and it becomes difficult to ignite, resulting in an ignition mistake. Further, when the control valve provided in the communication hole is formed as a poppet valve, the air flow is introduced in a thin film form, so that a phenomenon occurs in which the flame does not propagate even when dispersed and ignited in the sub chamber. Therefore, the gas engine has a problem of how to secure an emergency power supply.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems. In normal operation, an engine is driven by using natural gas as a fuel, and the supply flow rate of the natural gas is a predetermined value due to a trouble of the gas fuel supply system. In an emergency such as when the following occurs, the engine is driven in a diesel cycle using liquid fuel as fuel, and it is possible to operate the engine satisfactorily during both normal time and emergency to secure electric energy, When using natural gas as a fuel, natural gas is supplied to the gas chamber provided in the upper part of the sub-chamber by opening the gas fuel supply valve, and the sub-chamber control valve is provided in the through hole that connects the gas chamber and the sub-chamber. Arranged, forming a rich mixture in the gas chamber, compressing only the intake air between the main chamber and the sub chamber to increase the compression ratio, and controlling the sub chamber with the air in the main chamber and the sub chamber raised to a high temperature Open the valve to raise the subchamber The compressed air to flow into the gas chamber, then ignited and combusted in a short period of time by which once mixed with natural gas and highly compressed air of the gas chamber, suppressing state generation of the NO _X as rich state fuel gas chamber by burning, flame and to complete the combustion in a short time to realize by making blown into the main chamber uniform lean combustion through antechamber from the gas chamber, NO _X, HC
Etc., increase thermal efficiency, prevent self-ignition of gas fuel to prevent knocking, and in an emergency, inject liquid fuel from the fuel injection nozzle provided in the sub chamber to fuel the sub chamber. rich in burned suppressing state generation of NO _X, the flame and to achieve a uniform lean combustion by making blown into the main chamber from the auxiliary chamber to complete combustion in a short period of time, NO _X,
It is to provide a multi-fuel engine capable of reducing the generation of HC and the like.

[0008]

In order to achieve the above object, the present invention is constructed as follows. That is, according to the present invention, the sub chamber formed in the cylinder head, the main chamber formed on the cylinder side communicating with the sub chamber through the communication hole, the natural gas fuel is supplied through the gas fuel supply passage, and the sub chamber is provided. A gas chamber formed in the cylinder head that communicates with the upper part of the cylinder head through a through hole, a gas fuel supply valve for opening and closing a gas introduction port that communicates the gas chamber and the gas fuel supply passage, the gas chamber and the A sub-chamber control valve for opening and closing the through hole that communicates with the sub-chamber, a fuel injection nozzle for supplying liquid fuel to the sub-chamber, and the sub-chamber control valve for deactivating the fuel injection nozzle during normal operation And the gas fuel supply valve are operated to open and close by operating the gas fuel, and the sub-chamber control valve and the gas fuel supply valve are maintained in a closed state during an emergency operation. It said controller for performing control in the sub-chamber operated by injecting a liquid fuel, to a multi-Hugh el engine which is characterized by being configured from.

Further, in this multi-fuel engine, a glow plug is provided in the sub-chamber to assist starting in an emergency operation in which liquid fuel is injected from the fuel injection nozzle into the sub-chamber. An opening / closing valve and a flow rate sensor are provided in the gas fuel supply passage. Further, the controller closes the on-off valve to perform an emergency operation in response to the gas fuel flow rate value by the flow rate sensor being less than or equal to a specified value, and opens the on-off valve to respond to the gas fuel flow rate value above the specified value to perform normal operation. The control is performed. Further, the engine for switching between natural gas fuel and liquid fuel has an electromagnetic valve drive device that operates the gas fuel supply valve and the sub chamber control valve with electromagnetic force.

[0010]

The multi-fuel engine according to the present invention is
It is configured as described above and operates as follows. That is, this multi-fuel engine forms a gas chamber and a sub chamber in the cylinder head, communicates the main chamber on the cylinder side with the sub chamber through a communication hole, and allows natural gas fuel to pass through the gas fuel supply passage to the gas. Gas fuel supply valve for opening and closing a gas introduction port that supplies gas to the chamber and connects the gas chamber and the gas fuel supply passage, and a sub opening for opening and closing a through hole that connects the gas chamber and the sub chamber. A chamber control valve is provided, a fuel injection nozzle for supplying liquid fuel to the sub chamber is provided, and the controller deactivates the fuel injection nozzle during normal operation and opens and closes the sub chamber control valve and the gas fuel supply valve. Control to operate with gas fuel is performed, and during an emergency operation, the sub chamber control valve and the gas fuel supply valve are maintained in a closed state, and liquid fuel is injected from the fuel injection nozzle into the sub chamber to operate. Since it is configured to perform control, it is possible to supply gas fuel of natural gas during normal times to drive the engine, and to supply fuel to the engine immediately from the supply of natural gas fuel even in an emergency such as when gas fuel is not supplied. The engine can be driven by a diesel cycle by switching to fuel and supplying liquid fuel to the sub chamber from the fuel injection nozzle.

Further, by opening the gas fuel supply valve arranged in the gas chamber, natural gas is supplied to the gas chamber, and the natural gas can stay in the gas chamber and the through hole. Therefore, a rich mixture is formed in the region of the gas chamber and the through hole, and when hot air pressurized in this state is introduced into the gas chamber from the sub chamber through the through hole, the gas chamber and Ignition and combustion are reliably generated in the region of the through hole, flame propagation is well performed, and no ignition mistake occurs. In this phenomenon, at the time of partial load, the retention effect of the natural gas in the vicinity of the gas chamber outlet is exhibited, and the ignition and combustion proceeds smoothly.

Further, the sub-chamber control valve is provided in the through hole, and when the sub-chamber control valve is closed, natural gas is supplied to the gas chamber and the main chamber and the sub-chamber are supplied. Intake air is supplied to. Therefore, even if the intake air is highly compressed in the main chamber and the sub chamber, it is not introduced into the gas chamber unless the through hole is opened, and therefore the gas fuel supplied to the gas chamber is not supplied. Since it does not contain air, it does not self-ignite and knocking does not occur. Next, the sub-chamber control valve opens the through hole, whereby highly compressed intake air flows into the gas chamber from the main chamber and the sub-chamber, and gas fuel and intake air are mixed in the gas chamber. ignited by the occurrence of the NO _X is suppressed at high burn in large fuel-rich equivalence ratio. Further, the air-fuel mixture that is ignited and burned in the gas chamber is ejected into the sub-chamber through the sub-chamber control valve, the flame entrains the air in the sub-chamber to proceed with combustion, and then the flame and unburned mixture are generated. Gas such as air is diffused and ejected from the sub-chamber through the plurality of communication holes to the periphery of the cylinder of the main chamber, and the ejection energy of the gas is effectively used to improve the air utilization rate in the main chamber. Then, the mixture is promptly mixed with air, the lean combustion is promoted, the combustion period is shortened to complete the combustion, and the generation of HC, soot, etc. is suppressed.

Also, this multi-fuel engine is
When a trouble or the like occurs in the gas fuel supply system, the on-off valve, the gas fuel supply valve and the sub chamber control valve are closed, and the fuel injection nozzle is driven to spray liquid fuel into the sub chamber. After switching to operation, the engine is driven by a diesel cycle and the generator installed in the engine is operated to generate electricity. That is, this multi-fuel engine
It has a safety function when used as a single electricity supply system. At this time, the gas fuel, ie, natural gas, has a higher autoignition temperature and a longer ignition delay than the liquid fuel, ie, light oil, so that the diffusion combustion is slow and the combustion period is long. At this time, light oil is mixed and burned, but light oil has a characteristic of promoting ignition, the diffusion combustion region becomes active, and the combustion period is shortened. Therefore, in this multi-fuel engine, switching from natural gas to light oil can be performed smoothly.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a multi-fuel 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 the multi-fuel engine according to the present invention, FIG. 2 is a diagram showing the timing at the time of fuel switching of the multi-fuel engine, and FIG. 3 is a normal valve of this multi-fuel engine. A diagram showing the timing,
And FIG. 4 is a diagram showing the valve timing in an emergency of this multi-fuel engine.

This multi-fuel engine can be applied as a cogeneration engine or an automobile engine as shown in the figure.
It is switched so that either the gas fuel or the liquid fuel is supplied by the command of 0, the gas fuel is supplied to the gas chamber 6 during the normal operation, and the gas chamber 6 is driven during the emergency operation.
It is driven by supplying liquid fuel to the sub chamber 2 in a state where the sub chamber 2 and the sub chamber 2 are cut off. Therefore, when this multi-fuel engine is applied to a cogeneration engine equipped with a generator, the engine is driven by liquid fuel even in an emergency such as when the gas fuel supply amount drops and The power source can be secured, and the power source can be always secured together with the regular power source when driven by gas fuel.

This multi-fuel engine includes a cylinder block 18, a cylinder head 17 fixed to the cylinder block 18 via a gasket, intake and exhaust ports 22 and 24 formed in the cylinder head 7, and intake and exhaust ports 22 and 24. Reciprocates in the cylinder 25 formed in the cylinder liner fitted in the hole formed in the cylinder block 18, the sub chamber 2 and the gas chamber 6 formed in the cylinder head 17, The piston 19, the main chamber 1 formed on the cylinder 25 side, and the main chamber 1
It has a communication hole 9 that communicates with the sub chamber 2. Communication hole 9
Are inclined in the peripheral direction of the cylinder 25 from the sub chamber 2 side toward the main chamber 1 side.

In this multi-fuel engine,
The sub-chamber 2 and the gas chamber 6 are communicated with the head portion, that is, the upper portion of the sub-chamber 2, through a through hole 7 in the throttle portion. A gas inlet 26 is formed in the gas chamber 6, and a gas fuel supply valve 5 is arranged in the gas inlet 26. Natural gas as fuel, that is, natural gas, is housed in a natural gas supply source such as a gas fuel tank or a gas fuel pressure accumulating chamber (not shown) for accumulating the natural gas. Natural gas is a gas fuel supply valve 5
When the gas inlet 26 is opened, the gas fuel supply passage 16
Is supplied to the gas chamber 6 through the gas introduction port 26. A sub-chamber control valve 4 is provided in a through hole 7 that connects the gas chamber 6 and the sub-chamber 2 to each other. The sub chamber control valve 4 is set to open the through hole 7 near the end of the compression stroke. Further, the gas fuel supply valve 5 is set to open the gas introduction port 26 in a state where the through hole 7 is closed by the sub chamber control valve 4. Further, a fuel injection pump 11 is provided to supply the liquid fuel to the sub chamber 2, and the injection port of the fuel injection nozzle 3 is opened in the sub chamber 2. Furthermore,
A glow plug 8 is provided in the sub chamber 2 for assisting the starting when the liquid fuel is injected from the fuel injection nozzle 3 into the sub chamber 2 by the operation of the fuel injection pump 11 to operate.

The multi-fuel engine is also provided with a controller 10 for issuing a command to switch the fuel supplied to the engine to either natural gas fuel or liquid fuel. The gas fuel supply passage 16 is provided with a solenoid opening / closing valve 14 and a flow rate sensor 15. The controller 10 is supplied with electric power from the battery 20, performs opening / closing operations of the sub chamber control valve 4, the gas fuel supply valve 5, and the solenoid opening / closing valve 14 by the electric power supplied from the battery 20, and the fuel injection pump 11 and The operation of the glow plug 8 can be controlled. The sub-chamber control valve 4 is operated by electromagnetic force by the electromagnetic valve drive device 12 according to a command from the controller 10, and the gas fuel supply valve 5
Is operated by electromagnetic force by the solenoid valve drive device 13 according to a command from the controller 10, and the solenoid opening / closing valve 14 is operated by a solenoid 27 according to a command from the controller 10.

In this multi-fuel engine,
In particular, during normal operation, the controller 10 deactivates the fuel injection nozzle 3 and opens / closes the sub-chamber control valve 4 and the gas fuel supply valve 5 to perform control to operate with gas fuel, and to perform emergency operation. At times, the sub-chamber control valve 4 and the gas fuel supply valve 5 are maintained in a closed state, and the fuel injection pump 11 is operated to inject liquid fuel from the fuel injection nozzle 3 into the sub-chamber 2 to operate. is there. Also, the controller 1
As shown in FIG. 2, the 0 indicates that the solenoid 27 is responsive to the gas fuel flow rate value by the flow rate sensor 15 being less than the specified value Q _1.
The solenoid opening / closing valve 14 is closed to perform an emergency operation, and the solenoid 27 is opened to open the solenoid opening / closing valve 14 in response to the gas fuel flow rate value being equal to or more than the specified value Q _1. A command is issued to control the operation. At this time, when the gas fuel flow rate value is equal to or less than the specified value Q ₀ , the solenoid opening / closing valve 14 completely closes the gas fuel supply passage 16, and the liquid fuel supply amount from the fuel injection pump 11 becomes the total amount. Then, when the gas fuel flow rate value is between the specified value Q ₁ and the specified value Q ₀ , there is a state where the gas fuel is supplied and the liquid fuel is supplied, and the overlap period between the gas fuel and the liquid fuel is It does occur, but does not pose a problem because it burns on subsequent operation with different fuels.

The multi-fuel engine according to the present invention is constructed as described above and functions as follows. As shown in FIG. 3 or 4, this multi-fuel engine is operated by sequentially repeating four strokes of an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke.

In this multi-fuel engine,
During normal operation, the intake valve 21, the exhaust valve 23, the auxiliary chamber control valve 4, and the gas fuel supply valve 5 are operated at the valve timings shown in FIG. That is, this multi-fuel engine uses the intake valve 2 in the intake stroke.
1 opens the intake port 22 to supply the intake air to the main chamber 1, and the auxiliary chamber control valve 4 closes the through hole 7 to open the gas introduction port 26 with the gas fuel supply valve 5 to open the gas fuel passage. Natural gas is supplied from the natural gas supply source to the gas chamber 6 through 16. At this time, since a small amount of exhaust gas after combustion remains in the gas chamber 6, when natural gas is introduced into the gas chamber 2, the gas fuel receives heat and is activated in the gas chamber 2.

Next, in this multi-fuel engine, in the compression stroke, the through hole 7 is closed by the sub chamber control valve 4, and the intake air is highly compressed in the main chamber 1 and the sub chamber 2 to increase the compression ratio. Enlarge. Next, the sub-chamber control valve 4 opens the through hole 7 near the end of the compression stroke, and the compressed air having a high compression and high temperature (for example, 650 ° C.) is passed through the through hole 7 from the main chamber 1 through the sub chamber 2 to the gas chamber 6 Inflow to. The air introduced into the gas chamber 6 is mixed with the natural gas supplied to the gas chamber 6 and ignited and burned, and the rich air-fuel mixture remaining in the vicinity of the gas chamber 6 and the through hole 7 is the sub-chamber 2 Combustion is surely progressed while being pushed out. Moreover, the ignition combustion in the gas chamber 6 proceeds smoothly combustion involving air in to flame propagation subchamber within 2, the NO _X in the fuel-rich been a rapid combustion in the subchamber 2 It burns in a reduced state. Next, sub-chamber 2
Gas such as flame and unburned air-fuel mixture is ejected to the main chamber 1 and moves to the expansion stroke to promote mixing with the fresh air existing in the main chamber 1 to increase the combustion speed and burn in a short period of time. Complete. In the expansion stroke, the open state of the through hole 7 is maintained, a flame is jetted from the sub chamber 2 to the main chamber 1 to perform work, and the through hole 7 is closed by the sub chamber control valve 4 near the end of the exhaust stroke.

In this multi-fuel engine, as described above, the gas chamber 6 is provided with the through hole 7 and the gas introduction port 26, and the natural gas from the natural gas supply source is closed by the sub chamber control valve 4. In this state, the air is supplied from the gas inlet 26 to the gas chamber 6, and the intake air sucked from the intake port 22 into the main chamber 1 and the sub chamber 2 is closed by the sub chamber control valve 4 to close the through hole 7. Since the piston 19 is compressed in the upward compression stroke while the intake air is not supplied to the natural gas 6, even if the intake air is highly compressed in the main chamber 1, the natural gas supplied in the gas chamber 6 remains in the main chamber. Since 1 and the sub chamber 2 are shut off by the sub chamber control valve 4, the natural gas does not self-ignite and knocking does not occur. Further, since the sub chamber control valve 4 opens the through hole 7, the intake air having a high compression ratio from the main chamber 1 and the sub chamber 2 flows into the gas chamber 6, and the fuel gas and the intake air are mixed and ignited. and, at high combustion with large fuel-rich equivalence ratio, NO _X, the generation of HC and the like can be suppressed.

In this multi-fuel engine,
Although not shown, the main chamber 1 and the sub chamber 2 are formed in a heat shield structure by a wall body made of ceramics having excellent heat resistance and a heat shield layer formed between the wall body and the cylinder head 17. In that case, the heat shield of the combustion chamber can be increased and the thermal efficiency can be improved. Further, the main chamber 1 can be constituted by a cavity formed in the piston head made of ceramics having excellent heat resistance, and similarly, the thermal efficiency can be improved.

In this multi-fuel engine,
When the flow rate sensor 15 detects that the flow rate of gas fuel has dropped below a predetermined flow rate, the controller 10 energizes the solenoid 27 in response to the detection signal and closes the gas fuel supply passage 16 with the solenoid opening / closing valve 14. Control to shut off the supply of gas fuel to the gas chamber 6. The valve timing at this time is, as shown in FIG.
Controls the gas fuel supply valve 5 to keep the gas inlet port 26 closed and the sub chamber control valve 4 to keep the through hole 7 closed. On the other hand, the controller 10 is the fuel injection pump 1
1 is activated, and the glow plug 8 is activated. Therefore, this multi-fuel engine comes to be driven in a diesel cycle with liquid fuel.

[0026]

The multi-fuel engine according to the present invention is constructed as described above and has the following effects. That is, in this multi-fuel engine, a gas chamber and a sub chamber are formed in a cylinder head, a main chamber on the cylinder side is formed, a gas fuel supply valve and a sub chamber control valve are provided, and a liquid fuel is provided in the sub chamber. A fuel injection nozzle for supplying the fuel is provided, and the controller inactivates the fuel injection nozzle during normal operation and controls the sub-chamber control valve and the gas fuel supply valve to open and close to operate with gas fuel. During operation, the sub-chamber control valve and the gas fuel supply valve are maintained in a closed state, and liquid fuel is injected from the fuel injection nozzle into the sub-chamber to control the operation. In addition to being driven by fuel, it is driven by liquid fuel even in an emergency, and when a generator is installed for a multi-fuel engine, it is normally used as a regular power source. Of course it can be secured, can be secured emergency power in an emergency, it is preferable to apply the cogeneration type engine.

Natural gas can be introduced into the gas chamber in a state where the through hole is closed, and intake air is introduced into the main chamber and the sub chamber in a state where there is no natural gas, and the intake air is introduced into the gas chamber. Can be highly compressed. Therefore, even if the air is highly compressed in the main chamber and the sub chamber, the natural gas does not self-ignite, and knocking does not occur. And
By opening the through hole by the sub-chamber control valve, high-temperature compressed air is introduced from the sub-chamber and the main chamber into the gas chamber, and rapidly mixed with the gas fuel existing in the gas chamber, Ignite and burn. In particular, since a rich air-fuel mixture exists in the vicinity of the through hole, it is ignited and satisfactorily ignited, and the combustion proceeds with smooth flame propagation.

In this multi-fuel engine, the intake air can be highly compressed in the main chamber and the sub-chamber, and the gas fuel is compressed and sealed in the gas chamber in a state where no air is present. Since the increased gas fuel is supplied, the gas fuel does not self-ignite, and a proper gas fuel can be supplied to the gas fuel. In addition, a small amount of exhaust gas after combustion remains in the gas fuel, and when the gas fuel is introduced into the gas chamber, the gas fuel receives heat and is activated in the gas chamber. Further, even if the intake air has a high compression pressure in the main chamber and the sub chamber, the gas chamber is closed by the sub chamber control valve to shut off the main chamber and the sub chamber from the gas chamber. The activated gas fuel in the gas chamber does not self-ignite, and knocking does not occur.

Further, since the sub-chamber control valve is actuated to open the through hole, the air that has been highly compressed and has a high temperature through the sub-chamber from the main chamber flows into the gas chamber all at once.
The mixture of the gas fuel and the intake air is accelerated at once and ignited,
Since the gas chamber burns at high speed in a fuel-rich state with a large equivalence ratio, the generation of NO _X is suppressed. Then, the pressure in the gas chamber increases at once due to the combustion, and the combustion is promoted. At the same time, while the air in the sub chamber is entrained from the gas chamber through the through hole, the flame blows into the main chamber at a stretch, The flame mixes with fresh air in the main chamber,
Accelerates lean combustion to increase combustion speed and completes ideal tertiary combustion in a short period of time. Therefore, this multi Hugh el engine, NO _X, can significantly reduce the generation of HC and the like, can provide a high efficiency of the engine.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a multi-fuel engine according to the present invention.

FIG. 2 is a diagram showing an example of switching timing at the time of fuel switching of this multi-fuel engine.

FIG. 3 is a diagram showing an example of valve timing in a normal state of this multi-fuel engine.

FIG. 4 is a diagram showing an example of an emergency valve timing of this multi-fuel engine.

[Explanation of symbols]

 1 Main Chamber 2 Sub Chamber 3 Fuel Injection Nozzle 4 Sub Chamber Control Valve 5 Gas Fuel Supply Valve 6 Gas Chamber 7 Through Hole 8 Glow Plug 9 Communication Hole 10 Controller 11 Fuel Injection Pump 12, 13 Solenoid Valve Drive Device 14 Solenoid Open / Close Valve 15 Flow meter 16 Gas fuel supply passage 17 Cylinder head 19 Piston 25 Cylinder 26 Gas inlet

Claims (5)

[Claims] 1. A sub chamber formed in a cylinder head,
A main chamber formed on the cylinder side that communicates with the sub chamber through a communication hole, and is formed in the cylinder head that is supplied with natural gas fuel through a gas fuel supply passage and communicates with an upper portion of the sub chamber through a through hole. A gas chamber, a gas fuel supply valve for opening and closing a gas inlet that connects the gas chamber and the gas fuel supply passage, and a sub chamber for opening and closing the through hole that connects the gas chamber and the sub chamber. Control valve, fuel injection nozzle for supplying liquid fuel to the sub-chamber, and deactivate the fuel injection nozzle during normal operation, and open and close the sub-chamber control valve and the gas fuel supply valve to operate on gas fuel Control for maintaining the sub-chamber control valve and the gas fuel supply valve in a closed state during an emergency operation and injecting liquid fuel into the sub-chamber from the fuel injection nozzle to operate. Over La, multi Hugh el engine which is characterized by being configured from. 2. The multi-chamber according to claim 1, wherein a glow plug is provided in the sub chamber to assist starting in an emergency operation in which liquid fuel is injected from the fuel injection nozzle into the sub chamber to operate. Fuel engine. 3. The multi-fuel engine according to claim 1, wherein an opening / closing valve and a flow rate sensor are provided in the gas fuel supply passage. 4. The controller closes the on-off valve in response to a gas fuel flow rate value by the flow rate sensor being below a specified value to perform an emergency operation, and opens the on-off valve in response to a value above the specified value. The multi-fuel engine according to claim 3, wherein control for performing normal operation is performed. 5. The multi-fuel engine according to claim 1, further comprising an electromagnetic valve driving device that operates the gas fuel supply valve and the sub chamber control valve with electromagnetic force.