JPH05321689A - Method of scavenge of gaseous fuel engine and device therefor - Google Patents

Abstract

PURPOSE:To prevent afterburn by replacing at least residual gaseous fuel in an exhaust system by non-combustible gas in a condition where supply of the gaseous fuel is disconnected before enging starting operation and/or when an engine is stopped. CONSTITUTION:Hydrogen flow regulation valves 12, 13 and a closed type solenoid valve 14 are provided in a hydrogen supply line 9b downstream of a pressure regulator 10, and hydrogen gas is injected from a hydrogen injection valve 15 through hydrogen supply lines 9c, 9d downstream of it. A controller 70 closes the solenoid valve 14 to disconnect supply of hydrogen gas when an ignition switch is at an OFF position, and when an engine rotation speed becomes a specified value or less, a changing valve 73 is opened to actuate a power-driven air pump 71 to supply air to an intake passage 39. When the engine rotation speed becomes zero, a changing valve 75 is opened to supply air to an exhaust passage 46. When time is up, the power-driven air pump 71 is stopped, and the changing valves 73, 75 are closed. Afterburn is thus prevented.

Description

Detailed Description of the Invention

[0001]

The present invention relates to, for example, hydrogen, methane,
The present invention relates to a scavenging method and an apparatus for a gas fuel engine in which a combustible gas such as ethane is driven as a fuel.

[0002]

2. Description of the Related Art Recently, various gas fuel engines using combustible gases such as hydrogen, methane and ethane as fuel have been proposed. In particular, hydrogen is expected as a pollution-free engine because it does not generate carbon dioxide gas by combustion and does not discharge harmful unburned components.

By the way, in a vehicle equipped with a gas fuel engine using hydrogen gas as a fuel, as shown in a skeleton diagram in FIG. 9, a fuel tank 100 containing a hydrogen storage alloy as a hydrogen fuel source is used. After communicating with the engine 101 through the pipe line 102, the hydrogen storage alloy is heated to adjust the pressure of the generated hydrogen gas, and then the hydrogen gas is sent to the combustion chamber of the engine 101, where it is exploded by ignition of the spark plug. Is configured to start.

When stopping the engine 101,
The ignition of the spark plug is stopped and the supply of hydrogen gas to the engine 101 is cut off.

Exhaust gas discharged from the engine 101 to the exhaust pipe 103 is discharged into the atmosphere through the silencer 104.

However, when the ignition switch is turned off by the driver to stop the engine 101, or when the engine 101 itself stops due to a start failure, engine stall, etc., unburned hydrogen gas remains in the silencer 104. , When the engine 101 is restarted, the hydrogen mixture is generated by static electricity generated by the flow of hydrogen gas remaining in the silencer 104.
There was a problem of burning within 4 (afterburn). Especially when the silencer 104 is at a high temperature, the hydrogen gas tends to be ionized and the afterburn tends to occur.

Further, in an engine employing a fuel premixing system in which hydrogen gas and air are premixed using a vaporizer and then supplied to the engine, hydrogen gas remains in the carburetor and the intake passage when the engine is stopped. However, when restarting the engine, new hydrogen gas is added to the above-mentioned remaining hydrogen gas to increase the hydrogen concentration of the air-fuel mixture, and static electricity generated by the flow of this hydrogen gas causes There was a problem that was burned in the intake passage (backfire).

In order to avoid such backfire, for example, in the "hydrogen engine stop method" disclosed in Japanese Patent Laid-Open No. 2-86921, the engine ignition operation is performed when the engine is stopped. In the state where is maintained, by shutting off the gas flow passage that connects the hydrogen tank and the engine, and burning the hydrogen gas in the path from the shutoff point to the combustion chamber of the engine in the engine,
It is intended that no hydrogen gas be left in the path.

Further, in the "method for starting a hydrogen engine" disclosed in Japanese Patent Laid-Open No. 2-86923, a starter is cut off in a state where a gas flow passage communicating between a hydrogen tank and the engine is cut off before starting the engine. The (starting motor) is operated to idle the engine, whereby the hydrogen gas remaining in the path from the communication passage cutoff portion to the combustion chamber of the engine is exhausted.

[0010]

However, in the above-described "method for stopping the hydrogen engine", when the engine is stopped, the hydrogen gas is not supplied even if the ignition operation is maintained with the supply of the hydrogen gas interrupted. When shut off, the air-fuel ratio becomes extremely lean, causing misfire and stopping the engine.Therefore, hydrogen gas remains in the exhaust system, and this residual hydrogen gas flows at restart and static electricity is generated. There was a risk of causing afterburn.

Further, in the above-mentioned "method for starting the hydrogen engine", the engine is made to idle prior to starting. However, due to this idling, the hydrogen gas remaining in the intake system and the exhaust system flows and static electricity is generated. However, backfire and afterburn may occur.

In view of the above problems, the present invention avoids the occurrence of backfire and afterburn when the engine is restarted by completely exhausting the gaseous fuel before starting the engine and / or when stopping the engine. It is an object of the present invention to provide a scavenging method for a gas fuel engine and a device therefor.

[0013]

In order to achieve the above object, the method for scavenging a gas fuel engine according to the invention of claim 1 interrupts the supply of the gas fuel before the engine starting operation and / or when the engine is stopped. In this state, at least the gaseous fuel remaining in the exhaust system is replaced with an incombustible gas. Air or EGR gas is used as the non-combustible gas.

According to a second aspect of the present invention, there is provided a scavenging method for a gas fuel engine, wherein the replacement of the gaseous fuel with the incombustible gas in the method according to the first aspect interrupts the supply of the gaseous fuel at the time of engine stop operation, and then the incombustibility. It is characterized in that it is performed by supplying gas to the engine.

According to a third aspect of the present invention, there is provided a scavenging method for a gas fuel engine, wherein the supply of the non-combustible gas in the second aspect is started before the engine speed reaches zero and for a predetermined period after the engine is stopped. It is characterized by continuing until.

According to a fourth aspect of the present invention, there is provided a gas fuel engine scavenging method, wherein the replacement of the gaseous fuel with the incombustible gas in the first method is carried out prior to cranking the engine during engine starting operation. Is performed by supplying non-combustible gas to the intake system and the exhaust system in a state where the supply of the gas is cut off.

According to a fifth aspect of the present invention, there is provided a gas fuel engine scavenging device for detecting a state before an engine starting operation and / or an engine stop state, and shutting off the supply of the gaseous fuel based on the detection by the detecting means. Means to do
In a state where the supply of the gaseous fuel is shut off by the shutoff means,
At least a means for replacing the gaseous fuel remaining in the exhaust system with an incombustible gas is provided.

According to a sixth aspect of the present invention, there is provided a scavenging device for a gas fuel engine, wherein the means for replacing the gaseous fuel and the incombustible gas in the device according to the fifth aspect shuts off the supply of the gaseous fuel by the shutoff means when the engine is stopped. It is characterized in that it comprises means for supplying the above-mentioned incombustible gas to the engine after being discharged.

According to a seventh aspect of the present invention, there is provided a scavenging device for a gas fuel engine, wherein in the device according to the sixth aspect, means for detecting that the engine speed has become equal to or lower than the engine rotational speed and means for detecting that the engine has stopped. And a means for timing a predetermined period after the engine is stopped, the supply of the non-combustible gas by the non-combustible gas supply means is started by detecting that the engine speed has become equal to or lower than a predetermined speed, and after the engine is stopped. It is characterized by being continued until a predetermined period of time elapses.

According to the eighth aspect of the present invention, there is provided a scavenging apparatus for a gas fuel engine, wherein the means for replacing the gaseous fuel with the non-combustible gas in the apparatus according to the fifth aspect prior to starting cranking at the time of engine starting operation, It is characterized in that it comprises means for supplying the non-combustible gas to the exhaust system.

According to a ninth aspect of the present invention, there is provided a scavenging apparatus for a gas fuel engine according to the fifth to eighth aspects, wherein the non-combustible gas is a tank in which exhaust gas obtained in a combustion state at an air-fuel ratio substantially equal to a theoretical air-fuel ratio is used. It is characterized by consisting of those stored in.

[0022]

Action and effect The method according to claim 1 and claim 5
According to the device described above, since the gaseous fuel remaining in the exhaust system is replaced with the non-combustible gas before the engine starting operation and / or when the engine is stopped, it is caused by the generation of static electricity accompanying the flow of the residual gaseous fuel at the time of restart. Afterburn can be reliably prevented.

According to the method of the second aspect and the apparatus of the sixth aspect, the gas fuel remaining in the intake system and the exhaust system is exhausted at the pressure of the non-combustible gas by supplying the non-combustible gas to the engine when the engine is stopped. Since it is extruded from the system to the outside, the occurrence of backfire and / or afterburn at the time of restart can be reliably prevented.

According to the method of the third aspect and the device of the seventh aspect, the non-combustible gas is supplied to the engine for a predetermined period even after the engine is stopped. Therefore, the engine idling is prolonged and the driver feels strange. Backfire and / or afterburn at the time of restart can be further reliably prevented without giving the above.

According to the method described in claim 4 and the device described in claim 8, since the non-combustible gas is supplied to the intake system and the exhaust system prior to the cranking of the engine during the engine starting operation, the intake system and the exhaust system. The gaseous fuel remaining in the system is completely discharged, and backfire and / or afterburn can be prevented from occurring.

According to the apparatus of the ninth aspect, as the non-combustible gas, the exhaust gas stored in the tank in the combustion state substantially equal to the stoichiometric air-fuel ratio, that is, the combustion gas containing less oxygen and hydrogen is used. The effect can be enhanced.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual configuration diagram showing a rotary piston engine to which the present invention is applied and which uses hydrogen gas as a fuel, and a rotary piston engine having two rotors is developed in the left and right directions. It is a thing.

In FIG. 1, the rotary piston engine is provided with a triangular rotor 2 in a rotor housing 1 having a peritrochoidal curve as an inner peripheral surface. Rotor 2 3
The two ridges are in contact with the inner peripheral surface of the rotor housing 1 via the apex seals, and the inner peripheral surface of the rotor housing 1, the outer peripheral surface of the rotor 2, and the rotor housing 1
Side housings attached to both sides of the (not shown)
Also, three working chambers 4 are defined by the intermediate housing 3, and the working chambers 4 change their volumes in accordance with the eccentric rotation of the rotor 2 to perform the Otto cycle operation. Then, the eccentric shaft 5 is rotationally driven with the eccentric rotation of the rotor 2.

The intermediate housing 3
1 is a wall member interposed between a cylinder F on the right side (front side) and a cylinder R on the left side (rear side) in FIG. 1, and the rotors 2 of the cylinders F and R are provided on both front and rear surfaces thereof. It comes in contact with and slides through a side seal. Also, the rotors 2 of both cylinders F and R operate with a phase difference of 180 °.

An intake port 6 is opened at a predetermined position of the side housing and the intermediate housing 3 facing the working chamber 4 in the intake stroke of each cylinder F, R, and the intake port 6 is associated with the rotation of the rotor 2. The hydrogen injection port 7 is opened on the inner peripheral surface of the rotor housing on the leading side of the above (see FIG. 2).

The hydrogen supply source (not shown) is, for example, a metal halide tank equipped with a hydrogen storage alloy capable of storing and releasing hydrogen, and between the hydrogen supply source and each hydrogen injection port 7. Is provided with a hydrogen supply line 9, and a pressure regulator 10 for reducing the pressure of the hydrogen gas to a constant pressure is provided in the hydrogen supply line 9.

A solenoid valve 11 is provided in the hydrogen supply line 9a upstream of the pressure regulator 10, and an accelerator pedal depressed by the driver is provided in the hydrogen supply line 9b downstream of the pressure regulator 10. Hydrogen flow control valve 12 that works with 8
Further, a hydrogen flow rate adjusting valve 13 which is opened and closed by a step motor 16 as an actuator and a normally closed solenoid valve 14 are interposed. Further, in the hydrogen supply line 9b, pressure sensors 29 and 29 are provided at positions between the pressure regulator 10 and the hydrogen flow rate adjusting valve 12 and between the hydrogen flow rate adjusting valves 12 and 13, respectively.
30 are arranged.

Hydrogen supply lines 9c and 9d branched into two are connected to the downstream end of the hydrogen supply line 9b, and the hydrogen gas supplied to the hydrogen supply lines 9c and 9d is attached to the rotor housing 1. The hydrogen injection valve 15 is used to inject from the hydrogen injection port 7 into the working chamber at the beginning of the compression stroke.

As shown in FIG. 2, the hydrogen injection valve 15 is provided with a valve passage 18 for communicating the hydrogen supply lines 9c and 9d with the hydrogen injection port 7 in a casing 17 thereof.
A poppet valve 19 is provided at the opening of the.

The poppet valve 19 has a stem 19a slidably inserted in a guide 20 fixed to a casing 17, and a valve face 19b at the tip is pressed and biased toward the seat 22 by a spring 21. There is. When the valve face 19b of the poppet valve 19 comes into close contact with the seat 22 by the urging force of the spring 21, the valve passage 18 is closed and shut off, and the poppet valve 19 slides against the urging force of the spring 21 to cause the valve passage to move. 18 is configured to open.

A cam shaft 23 is rotatably supported by the casing 17 at an obliquely upper side of the stem 19a of the poppet valve 19, and a cam 24 provided on the cam shaft 23 serves as a spring for the poppet valve 19. The valve passage 18 is opened and closed by a pressing operation against the biasing force of 21. As shown in FIG. 1, the camshaft 23 is linked to the eccentric shaft 5 by a timing belt or chain indicated by 25 in the drawing so as to be rotatable in synchronization therewith,
The poppet valve 19 is opened and closed at a predetermined timing in synchronization with the rotation of the eccentric shaft 5. The cams 24, 24 for driving the poppet valves 19, 19 of both cylinders F, R, respectively, are provided with a phase difference of 180 °, which is equal to the phase difference of the rotor 2 of the corresponding cylinders F, R.

A hydrogen flow rate adjusting valve 12 provided in the middle of the hydrogen supply line 9b and interlocking with the accelerator pedal 8 has a hydrogen introducing port 27 and a hydrogen introducing port 27 provided in a casing 26 thereof as shown in FIGS. 3 and 4. A valve passage 31 communicating with the outlet 28 is provided in the casing 26, and a poppet valve 32 for opening and closing the valve passage 31 is arranged in the valve passage 31.

The poppet valve 32 is a stem 32a connected to the end of an accelerator wire 33 connected to the accelerator pedal 8.
The stem 32a is inserted into the position sensor 40 provided in the casing 26. The poppet valve 32 is held in a manner that its valve face 32b is pressed and urged toward the valve seat 34 by a spring SP that is compressed inside the casing 26.

Further, the casing 26 of the hydrogen flow rate adjusting valve 12
A bypass passage 35 that bypasses the poppet valve 32 is provided therein, and a bypass passage valve 36 that is a needle valve is provided in the bypass passage 35. The bypass passage valve 36 is configured to open and close the bypass passage 35 by a diaphragm type actuator 37 that operates by negative intake pressure.

With this configuration, the accelerator pedal 8
When the pedal is not stepped on, the valve face 32b of the poppet valve 32 comes into close contact with the valve seat 34, and the valve passage 18 is hermetically shut off.At that time, the intake negative pressure activates the actuator 37 and the bypass passage valve 36. Has a bypass passage 35
Is opened, and a small amount of hydrogen gas is supplied to the hydrogen outlet 28 side through the bypass passage 35. On the other hand, when the accelerator pedal 8 is depressed, the poppet valve 32 is pulled upward against the biasing force of the spring SP to open the valve passage 31. And
Poppet valve detected by the position sensor 40
The opening degree of 32 is input to the controller (ECU) 70 as feedback information.

The hydrogen flow rate adjusting valve 13 is also provided on the downstream side of the hydrogen flow rate adjusting valve 12 whose opening and closing is controlled by the driver's will.
This hydrogen flow rate adjustment valve 13 is a flow rate adjustment valve that is driven to open and close by a controller 70 via a step motor 16 as an actuator, and has a predetermined air-fuel ratio depending on the operating state of the engine. Controlled to be obtained. Although detailed description of the configuration of the hydrogen flow rate adjusting valve 13 is omitted, as with the adjusting valve 12 described above, a poppet valve driven by a step motor 16 is provided inside and the opening degree of the poppet valve is set. A position sensor for outputting to the controller 70 as feedback information is provided.

The intake / exhaust system of the rotary piston engine is
It has a configuration as described below. That is, the venturi portion 41 is arranged in the intake passage 39 downstream of the air cleaner 38 in FIG. 1, and the air throttle valve 42 is provided downstream of the venturi portion 41. The air throttle valve 42 is opened and closed by a step motor 43 as an actuator, and is provided with a position sensor 44 for detecting its opening. The opening of the air throttle valve 42 detected by the position sensor 44 is also input to the controller 70 as feedback information.

The downstream side of the intake passage 39 has two intake passages 39.
The intake passages 39a and 39b are respectively branched to a and 39b, and are connected to the intake ports 6 and 6 of the cylinders F and R, respectively.

On the other hand, an exhaust passage 46 is connected to an exhaust port 45 formed in the rotor housing 1, and both cylinders F and R are connected.
The exhaust passages 46, 46 are joined to one exhaust passage 47, and an O ₂ sensor 48 for detecting the air-fuel ratio is arranged in the exhaust passage 47.

An air supply line 72 having an electric air pump 71 attached to one end is connected to the first intake passage 39, and a switching valve 73 is provided in the middle of the air supply line 72. Furthermore, the intake passage of the cylinder F on the front side
A communication passage 74 that connects the exhaust passage 46 to the exhaust passage 46, and a communication passage 74 that connects the intake passage 39b of the rear cylinder R to the exhaust passage 46.
Are provided, and a switching valve 75 is provided in each communication passage 74.

The electric air pump 71 and the switching valve 7
3 and 75 supply air to the intake passage 39 and the exhaust passage 46 before the engine start operation and / or at the time of stopping the engine, without stopping the flow of the mixture containing hydrogen gas remaining in the intake system and the exhaust system. It is provided for discharging to the outside, so that backfire and afterburn are reliably prevented from occurring during restart.

Here, the intermediate housing 3
Intake port 6 formed in the opening and rotor housing 1
The hydrogen injection port 7 opening to the inner peripheral surface of the above will open to the working chamber 4 as the rotor 2 moves, and its opening timing is set as shown in FIG. .. That is, the intake port 6 opens at a position where a crank angle of 32 ° has elapsed from the top dead center (TDC) at the end of the exhaust stroke, and the hydrogen injection port 7 is opened at 60 °, which is slightly delayed from this.
Opens. The intake port 6 closes at 50 ° from the bottom dead center (BDC) at the end of the intake stroke, and the hydrogen injection port 7
Will be closed about 100 degrees later and will close at 150 degrees. Therefore, the intake port 6 is 32 after TDC.
The hydrogen injection port 7 opens in the range of 288 ° with a crank angle from 0 ° to 50 ° after BDC, and the hydrogen injection port 7 is 60 ° after TDC to BDC.
It opens in the range of 370 ° with a crank angle of up to 150 °.
In addition, in the case of a rotary piston engine, from TDC to B
Up to DC, the crank angle is about 270 °.

On the other hand, the opening and closing timings of the poppet valve 19 of the hydrogen injection valve 15 at the time of starting and in the high load operation range are the same as the closing of the intake port 6 (50 ° after BDC) and the closing timing of the hydrogen injection port 7. The valve is set to close at 140 ° after BDC approximately equal to. Therefore, the poppet valve 19 is from 50 ° after BDC to 140 ° after BDC.
It is configured to open in the range of 90 °.

Next, when the engine is stopped, the solenoid valve 14,
A control routine executed by the controller 70 for the electric air pump 71 and the switching valves 73, 75 will be described with reference to the flowchart of FIG.

First, in step S1, the switching valve
73 and 75 are reset to the closed state, and it is determined in step S2 whether or not the ignition switch is turned off. If the ignition switch is in the OFF position, the solenoid valve 14 is closed in step S3 to cut off the supply of hydrogen gas to the engine, and in step S4.
In step S5, the engine speed Ne is detected, and it is checked in step S5 whether the engine speed Ne has become equal to or lower than a set value CN1 (engine stop determination speed, eg 350 rpm). If it is determined that the engine speed Ne has become less than or equal to the set value, the switching valve 73 is opened in step S6, and the electric air pump 71 is operated in step S7 to supply air to the intake passage 39.

Next, in step S8, the engine speed N is again set.
When e is detected and it is determined in step S9 that the engine speed has become zero, that is, when the engine has stopped, the timer is activated in step S10 and the switching valve 75 is opened in step S11. , Air is supplied to the exhaust passage 46. In the next step S12, it is determined whether or not the timer set time CT1 has elapsed. When the timer times out, in step S13 the electric air pump
71 is stopped, and the switching valves 73 and 75 are closed in step S14 to end the control.

On the other hand, when it is determined in step S2 that the ignition switch has not been turned off, the routine proceeds to step S15, where the engine speed Ne is detected, and in the next step S16, the engine speed Ne is set to the set value CN2 ( It is determined whether or not the engine stall determination rotational speed is, for example, 400 to 500 rpm) or more, and the determination in step S16 is "N".
If it is "O", it is determined that the engine is stalled, and the processes in and after step S3 are performed.

The above is a description of the structure and operation when the present invention is applied to a direct fuel injection type rotary piston engine using hydrogen gas as a fuel. It goes without saying that it can also be applied to a rotary piston engine adopting the method.

Furthermore, the present invention is not limited to the rotary piston engine described above, but can be applied to a reciprocating engine. An example in which the present invention is applied to a reciprocating engine is shown in FIGS. 7 and 8. ..

FIG. 7 is a diagram showing a port arrangement of the reciprocating engine, and FIG. 8 is a schematic sectional view showing elements corresponding to those in FIG.

The cylinder head 51 has two intake ports.
52, one exhaust port 53, and one hydrogen port 54 are formed so as to open in the combustion chamber 55, and each port 52 to 54 is a poppet valve that is driven to open and close by cams 56 and 57, respectively. 58 and 59 are provided.

The hydrogen gas supplied from the hydrogen supply line 9b is supplied to the hydrogen port 54 via the hydrogen manifold 60 by opening the solenoid valve 14, and the poppet valve 59 for opening and closing the hydrogen port 54 at a predetermined timing. Is directly supplied to the combustion chamber 55 at a predetermined timing.

Also in FIG. 8, an electric air pump 71, an air supply line 72, and a communication passage having the same functions as those in FIG.
74 and switching valves 73 and 75 are provided.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram of a rotary piston engine to which the present invention is applied.

FIG. 2 is an enlarged vertical cross-sectional view of a portion to which the hydrogen injection valve of FIG. 1 is attached.

FIG. 3 is an enlarged vertical cross-sectional view of a hydrogen flow rate control valve that works in conjunction with an accelerator pedal.

FIG. 4 is a vertical sectional view taken along line IV-IV in FIG.

FIG. 5 is a timing chart showing the opening period of each port and the hydrogen injection valve.

FIG. 6 is a flowchart of a control routine executed by the controller.

FIG. 7 is a diagram showing a port arrangement of a reciprocating engine to which the present invention is applied.

FIG. 8 is a schematic sectional view of a reciprocating engine to which the present invention is applied.

FIG. 9 is a skeleton diagram of a vehicle equipped with an engine that uses hydrogen gas as a fuel.

[Explanation of symbols]

 1 rotor housing 2 rotor 4 working chamber 6 intake port 7 hydrogen injection port 9 hydrogen supply line 12, 13 hydrogen flow control valve 14 solenoid valve 15 hydrogen injection valve 39 intake passage 70 controller 71 electric air pump 72 air supply line 73, 75 switching valve 74 passage

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takafumi Teramoto 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Motor Corporation

Claims (9)

[Claims] 1. A scavenging method for a gas fuel engine using a gas fuel containing at least hydrogen gas, the method comprising:
A scavenging method for a gas fuel engine, wherein at least the gas fuel remaining in the exhaust system is replaced with an incombustible gas in a state where the supply of the gas fuel is cut off. 2. The replacement of the gaseous fuel with the non-combustible gas is performed by supplying the non-combustible gas to the engine after shutting off the supply of the gaseous fuel at the time of engine stop operation. 1. A scavenging method for a gas fuel engine according to 1. 3. The gaseous fuel according to claim 2, wherein the supply of the non-combustible gas is started before the engine speed reaches zero and continues until a predetermined period after the engine is stopped. Engine scavenging method. 4. The replacement of the gaseous fuel with the non-combustible gas, in a state where the supply of the gaseous fuel is interrupted prior to cranking of the engine at the time of engine starting operation,
The scavenging method for a gas fuel engine according to claim 1, wherein the scavenging method is performed by supplying the non-combustible gas to an intake system and an exhaust system. 5. A scavenging device for a gas fuel engine using a gas fuel containing at least hydrogen gas, comprising means for detecting a state before an engine starting operation and / or an engine stop state, and detection based on the detection means. A means for cutting off the supply of the gaseous fuel, and a means for replacing at least the gaseous fuel remaining in the exhaust system with an incombustible gas in a state where the supply of the gaseous fuel is cut off by the cutting means. Characteristic gas fuel engine scavenging device. 6. The means for replacing the gaseous fuel with the incombustible gas comprises means for supplying the incombustible gas to the engine after the supply of the gaseous fuel is interrupted by the interrupting means at the time of engine stop operation. The scavenging device for a gas fuel engine according to claim 5. 7. A means for detecting that the engine speed has become equal to or lower than a predetermined speed when the engine is stopped, a means for detecting that the engine has stopped, and a means for measuring a predetermined period after the engine has stopped. The supply of the non-combustible gas by the non-combustible gas supply means is started by detecting that the engine speed becomes equal to or lower than a predetermined speed, and is continued until a predetermined period elapses after the engine is stopped. Item 6. A scavenging device for a gas fuel engine according to Item 6. 8. The means for replacing the gaseous fuel with the non-combustible gas comprises means for supplying the non-combustible gas to an intake system and an exhaust system prior to the start of engine cranking during an engine starting operation. The scavenging device for a gas fuel engine according to claim 5. 9. The gas fuel engine according to claim 5, wherein the non-combustible gas comprises exhaust gas obtained in a combustion state at an air-fuel ratio substantially equal to the stoichiometric air-fuel ratio and stored in a tank. Scavenging equipment.