JPH1089229A - Laser irradiation window fouling preventing device for laser ignition type engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser irradiation window fouling preventing device for a laser ignition type engine to prevent a laser irradiation window from being positioned directly facing a combustion chamber, improve the laser irradiation window, improve ignition of fuel by laser beams, and hold stable ignition performance for a long time. SOLUTION: In a laser ignition type engine wherein through collection of laser beams to the internal part of a cylinder and and irradiation of the interior of the cylinder with laser beams, plasma is generated and fuel is ignited for combustion, a small hole 11 having a small bore diameter is formed on the laser beam passage 2 of the inner wall of a combustion chamber 23 positioned above the top dead center of a piston 6 and a laser irradiation window 5 is disposed on the deep side of the small hole 11 through a small room 4a opened and closed by on-off members 13a and 13b. The on-off members 13a and 13b are constituted in a manner to be openable by a pressure in the vicinity of the top dead center of the piston 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser ignition type engine for converging and irradiating a laser beam in a cylinder to generate plasma and ignite and burn fuel, and to a device for preventing contamination of an irradiation window for irradiating the laser.

[0002]

2. Description of the Related Art An engine using a liquid fuel such as methanol condenses a laser beam in an injected fuel to generate a plasma, thereby igniting and burning. An apparatus shown in FIG. 4 as a conventional example is one of them.

In FIG. 1, a piston 6 is disposed in a cylinder so as to be movable up and down, and a fuel injection nozzle 8 is provided in a cylinder head 4, and a condenser lens 3 and a glass window 5 are arranged alongside the fuel injection nozzle 8. The configured laser light path is provided so that the laser light from the laser device 1 is focused on the piston 6 near the top dead center of the piston 6.

The laser light 2 emitted from the laser device 1 is condensed by a lens 3, passes through a glass window 5 provided in a cylinder head 4 of the engine, focuses on a piston 6, and generates a plasma 7. Then, the methanol 9 injected from the fuel injection nozzle 8 is ignited and burned. The laser light can be ignited even if it is directly focused on the injected methanol. The generation timing of the laser beam 2 is controlled by an engine rotation detector (not shown), and is synchronized with the methanol injection.

[0005]

In the laser ignition type engine according to the prior art described above, the glass window 5 for preventing the leakage of the combustion gas to the outside is directly opposed to the combustion chamber and directly in contact with the combustion gas. It is arranged to be. For this reason, the surface of the glass window 5 on the combustion chamber side is easily contaminated with combustion gas and the like, and the transmittance of laser light passing through the window decreases over time, and the energy of the laser applied to methanol decreases, igniting methanol. It becomes difficult to operate the engine stably for a long time.

In view of the above-mentioned circumstances, the present invention has a structure in which a laser irradiation window does not directly face a combustion chamber, or introduces gas into a small room facing the irradiation window, so that the explosion and expansion of the combustion chamber may occur. A laser irradiation window of a laser ignition type engine configured to discharge the gas into a combustion chamber, in which contamination of the irradiation window is improved, ignition of fuel by laser light is good, and stable ignition performance is maintained for a long time. An object of the present invention is to provide a stain prevention device.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a laser ignition type engine for converging and irradiating a laser beam in a cylinder to generate plasma and ignite and burn fuel, wherein a combustion chamber wall located above a piston top dead center is provided. A small-diameter hole is provided on the laser beam path, and a laser irradiation window is provided via a small room opened and closed by an opening and closing member on the back side of the small hole,
The opening and closing member is configured to be openable by a pressure near a piston top dead center.

The gas is introduced into the small chamber in synchronization with the rotation of the engine, the opening / closing member is opened during the expansion process after combustion, and the gas is discharged into the cylinder through the small hole. Is also an effective means of the present invention.

According to the present invention, as shown in FIG. 1, a piston 6 in a cylinder of a laser ignition type engine for generating plasma by condensing and irradiating a laser beam 2 in a cylinder and igniting and burning a fuel 9 is used. A small hole 11 having a small diameter is provided on the laser beam path on the inner wall of the combustion chamber 23 located above the point.

A laser irradiation window (glass window) is provided through a small room 4a opened and closed by an opening / closing member 13 at the back side of the small hole 11.
5 are provided. That is, a laser light path is provided between the small hole 11 and the laser light source (laser device) 1.
A glass window 5 that keeps the airtight with the outside of the cylinder and passes the laser is disposed, and the combustion chamber 23 is provided between the glass window 5 and the small hole 11 through a communication hole 20 formed in the combustion chamber wall. There is provided a space 21 that communicates with.

An opening / closing member 13 for opening and closing the small hole 11 according to the pressure P in the cylinder is provided in the space 21 by a spring 12.
Urged in the right direction, and can be moved left and right. This opening / closing member 13 is provided in the space 2 as shown in FIG.
1 is formed in a plate shape or a block shape to be fitted with the internal dimensions of the first hole, and an opening hole 14 having a diameter slightly larger than the small hole 11
Has been established.

The opening / closing member 13 is configured to be openable by a pressure near the top dead center of the piston 6, and a pressure P in the combustion chamber.
1 and 2 correspond to the elastic pressure of the spring 12.
The opening hole 14 communicates with the small hole 11 as shown in FIG.
Concentrates on the piston 6, ignites the fuel and causes a combustion explosion. At this time, since the explosive gas has a small diameter in the small hole 11, it becomes a resistance and is prevented from flowing into the small room 4a.

When the pressure in the combustion chamber expands and the pressure P
2A, the small holes 11 are closed at the rear portion 13b as shown in FIG.
It does not flow into a. And the pressure in the combustion chamber drops,
When the elastic pressure of the spring 12 exceeds the pressure P, the small hole 11 is closed by the front portion 13a as shown in FIG.

As described above, since the laser irradiation window does not directly face the combustion chamber and the small hole 11 through which the laser beam passes has a diameter small enough to allow the condensed laser beam to pass therethrough, The flow resistance of the gas in the combustion chamber into the small chamber is extremely small due to the fluid resistance of the hole 11, and the communication time between the small hole 11 and the opening hole 14 is extremely short during the compression and expansion steps of the piston 6. Very little gas flows from the combustion chamber into the chamber, so that the ignition of the fuel by the laser beam is good and stable ignition performance can be maintained for a long time.

As shown in FIG. 1, when gas is introduced from the air source 18 into the small chamber 4a in synchronization with the rotation of the engine, during the expansion process after combustion,
The opening / closing member 13 temporarily assumes the position shown in FIG. 3A, but as the pressure P in the combustion chamber decreases, the opening / closing member 13 moves rightward, and the small hole 11 and the opening hole 14 again communicate with each other.
Since the gas is discharged into the cylinder through the small hole 11, even if the combustion gas is flowing into the small chamber at that time, the combustion gas is discharged into the combustion chamber together with the gas.

Accordingly, by introducing the gas from the air source 18 into the small chamber 4a in synchronization with the rotation of the engine, the risk of obstructing the passage of the laser beam due to contamination of the laser irradiation window is improved. Thus, the ignition of the fuel by the laser beam is good, and the ignition performance can be maintained for a long time.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. It's just

FIG. 1 shows a configuration diagram according to an embodiment of the present invention. The same members as those in the conventional example are denoted by the same reference numerals. In the figure, a piston 6 is disposed in a cylinder so as to be movable up and down, and a fuel injection nozzle 8 is provided in a cylinder head 4. A condenser lens 3, a glass window 5, an opening / closing member 13 are arranged alongside the fuel injection nozzle 8. Opening 14 and combustion chamber 23
The laser light path composed of the small holes 11 opened on the wall is
The laser beam from the laser device 1 is arranged so as to be focused on the piston 6 near the top dead center of the piston 6.

Glass window 5 provided in the laser beam path
Is made of a transparent member that passes a laser while keeping the airtight state with the outside of the cylinder, and a small room 4a is provided below the glass window 5 so as to face the glass window. A space 2 communicating with the combustion chamber 23 through a communication hole 20 formed in the combustion chamber wall between the small hole 11 and the small hole 11.
1 is provided.

An opening / closing member 13 for opening and closing the small hole 11 according to the pressure P in the cylinder is provided in the space 21 by a spring 12.
Urged in the right direction, and can be moved left and right. This opening / closing member 13 is provided in the space 2 as shown in FIG.
1 is formed in a plate shape or a block shape to be fitted with the internal dimensions of the first hole, and an opening hole 14 having a diameter slightly larger than the small hole 11
Has been established.

One end of the spring 21 is located inside the space 21.
The opening / closing member 13 pressed by 2 is installed, and the other end receives the pressure of the combustion chamber from the communication hole 20, so that it can move according to the pressure P of the combustion chamber 23. The opening 14 of the opening / closing member 13 is adjusted so as to communicate with the small hole 11 on the wall surface of the combustion chamber 23 when the piston 6 reaches near the top dead center.

As shown in FIG. 1, the small room 4a
Are provided with pipes 19 and 15 for blowing air 22 (FIG. 3) into the small room 4a. The engine rotation detecting device 16 detects the rotation of the engine, controls the opening and closing of the valve 17, and controls the expansion of the engine. Small room 4a from air source 18 during the process
When the small holes 11 and the opening holes 14 coincide with each other, the air mixed with a small amount of the combustion gas inside the small room 4a is discharged into the combustion chamber.

The operation of the present embodiment configured as described above will be described. When the piston 6 reaches the vicinity of the top dead center, the pressure P in the combustion chamber 23 coincides with the resilient pressure of the spring 12, and as shown in FIGS. The opening holes 14 coincide with each other, and both communicate with each other.

At this time, methanol is injected from the fuel injection nozzle 8. In synchronization with the fuel injection, the laser light 2 emitted from the laser device 1 is condensed by the lens 3, and is condensed on the cylinder head 4 of the engine. After passing through the provided glass window 5, it is focused on the piston 6, generates plasma 7, and ignites the methanol 9 injected from the fuel injection nozzle 8 to burn and explode.

At this time, since the explosive gas has a small diameter in the small hole 11, it becomes a resistance and is prevented from flowing into the small room 4a.

When the gas in the combustion chamber 23 expands due to the explosion and the pressure P exceeds the elastic pressure of the spring 12, the small hole 11 is closed at the rear portion 13b as shown in FIG. It does not flow into the small room 4a. When the pressure in the combustion chamber decreases and the elastic pressure of the spring 12 exceeds the pressure P, the small hole 11 is closed by the front portion 13a as shown in FIG.

As described above, the small hole 11 through which the laser beam passes has a diameter small enough to allow the converged laser beam to pass therethrough. When the flow into the small chamber 4a is extremely small and the two small holes 11 and the opening hole 14 do not coincide with each other, the small chamber 4a is sealed by the opening / closing member 13, so that the gas in the combustion chamber 23 is released from the small chamber. The small hole 11 does not touch the glass window 5 and does not touch the glass window 5. Even when the small hole 11 and the opening hole 14 coincide with each other, the small hole 11 becomes a resistance and the gas is prevented from flowing.

Since the communication time between the small hole 11 and the opening hole 14 is extremely short during the compression and expansion steps of the piston 6, the gas flows from the combustion chamber into the small chamber 4a is extremely small, and The contamination of the laser irradiation window is improved, the ignition of the fuel by the laser light is good, and stable ignition performance can be maintained for a long time.

In this embodiment, as shown in FIG. 1, gas is introduced from the air source 18 into the small chamber 4a in synchronization with the rotation of the engine. Therefore, during the expansion process after combustion, the opening / closing member 13 temporarily assumes the position shown in FIG. 3A by receiving the increased pressure P from the communication hole 20, but as the pressure P in the combustion chamber decreases, the spring 13 12, the opening / closing member 13 moves rightward,
Again, the small hole 11 and the opening hole 14 communicate with each other.

At this time, the gas introduced into the small chamber 4a is discharged into the combustion chamber 23 through the small hole 11. Therefore, even if the combustion gas flows into the small room 4a, the combustion gas is discharged into the combustion chamber together with the gas.

Therefore, by introducing the gas from the air source 18 into the small chamber 4a in synchronization with the rotation of the engine, the possibility of obstructing the passage of the laser light due to contamination of the laser irradiation window is improved. Thus, the ignition of the fuel by the laser beam is good, and the ignition performance can be maintained for a long time.

In the present embodiment, the laser light is focused on the piston surface, but may be focused directly on the injected methanol. Further, the laser beam path can be configured to be focused on the injected fuel above the piston, and it is needless to say that the laser beam path is not limited to the embodiment disclosed above.

[0033]

As described above, according to the present invention, a small hole having a small diameter is provided on the laser beam path on the inner wall of the combustion chamber located above the top dead center of the piston, and the opening / closing member is provided on the back side of the small hole. A laser irradiation window is provided through a small room to be opened and closed, and the opening and closing member is configured to be openable by a pressure in a combustion chamber near a piston top dead center. Only when the small hole is opened, the laser beam passes and is radiated into the combustion chamber.At this time, the opening becomes a resistance and the gas in the combustion chamber is prevented from flowing into the small chamber. The opening and closing member is closed in the small hole so that gas in the combustion chamber does not flow.

When air is blown into the gap during the expansion process after combustion, the pressure in the combustion chamber is reduced by the expansion, and when the opening / closing member opens the small hole again, the small chamber is opened. The air inside can be discharged into the cylinder.

Therefore, according to the present invention, the laser irradiation window does not directly face the combustion chamber, the contamination of the irradiation window is improved, the ignition of the fuel by the laser beam is good, and the stable ignition performance is maintained for a long time. An apparatus for preventing contamination of a laser irradiation window of a laser ignition type engine can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an operation explanatory view of an opening / closing member.

FIG. 4 is a configuration diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser apparatus 2 Laser light 3 Lens 4 Cylinder head 5 Glass window (laser irradiation window) 6 Piston 7 Plasma 8 Injection nozzle 9 Methanol 11 Laser light transmission hole (small hole) 12 Spring 13 Opening / closing member 14 Laser light transmission hole ( Opening holes) 15, 19 Air piping 16 Engine rotation detector 17 Valve 18 Air source 20 Communication hole

Claims (2)

[Claims] 1. A laser ignition type engine for converging and irradiating a laser beam in a cylinder to generate plasma and ignite and burn fuel, wherein a small-diameter laser beam is formed on a laser beam path on a wall of a combustion chamber located above a piston top dead center. In addition to providing a small hole, a laser irradiation window is disposed through a small room opened and closed by an opening and closing member on the back side of the small hole, and the opening and closing member is configured to be openable by pressure near a piston top dead center. A contamination prevention device for a laser irradiation window of a laser ignition engine. 2. A gas is introduced into the small chamber in synchronization with the rotation of the engine, the opening / closing member is opened during an expansion process after combustion, and the gas is discharged into the cylinder through the small hole. The apparatus for preventing contamination of a laser irradiation window of a laser ignition type engine according to claim 1.