KR20030012603A - Injector nozzle of diesel engine for premixed combustion - Google Patents

Abstract

PURPOSE: A structure of an injector nozzle for pre-mixing combustion is provided to reduce the droplet size of fuel and hydrocarbon caused by the unburnt fuel by changing the shape of a nozzle into the shape of an airfoil. CONSTITUTION: An injector(20) is formed at the lower part of a cylinder head. A piston compresses and ignites the fuel injected from the injector in a combustion chamber. A plurality of nozzles(21) formed at the lower part of the injector and injecting fuel into the combustion chamber has the shape of an airfoil, and reduces the droplet size of injected fuel.

Description

Injector nozzle of diesel engine for premixed combustion

The present invention relates to an injector nozzle structure of a diesel engine for premixed combustion, and more particularly, due to the injection pressure and the droplet size of the fuel, more fuel collides with the combustion chamber wall, thereby reducing the generation of hydrocarbons due to unburned fuel. It relates to an injector nozzle structure of a diesel engine for premixed combustion.

In general, gasoline engines mix air and fuel uniformly before commencement of combustion, and ignite the mixture by ignition plugs to combust them.Diesel engines inhale only air and compress it at a high compression ratio to inject fuel at high pressure. The principle is to reach self-ignition combustion.

However, in the current gasoline engine, the compression ratio is considerably increased, but also the principle of spark ignition is injected into the cylinder in one or two stages as it is. The combustion is performed in a state.

On the other hand, in diesel engines, the combustion ignition method of increasing the ignition delay time of the fuel and taking the time from the start of the fuel injection to the ignition on purpose, the ignition of the self ignition after the homogenization of the mixture is actively conducted. While diesel engines are self-ignition and gasoline engines are spark plug ignition, they are rapidly becoming similar in the method of mixing fuel and air.

Recently, a general diesel engine is mainly used to burn fuel injected from an injector by swirling a bowl formed in a piston so that fuel and air are mixed well.

3 shows a combustion chamber of a conventional diesel engine, and an intake port 1 for intake of intake air and an exhaust port 2 for exhaust of exhaust gas are connected to an upper side of the combustion chamber 3, In the upper center portion of 3), an injector 4 for injection of fuel is formed. In particular, the injector 4 is usually formed to be inclined downward 5 to 6 nozzles 8 as shown in FIG.

And the combustion chamber 3 is provided with a piston (6) for air compression, the upper surface of the piston (6) as shown in the figure for the swirl for the fuel injected from the nozzle (8) of the injector (4) (7) is formed.

Therefore, when high pressure fuel is injected from the injector 1 while the air sucked through the intake port 1 is compressed by the rise of the piston 6, the fuel injected from the injector 4 is the piston 6. In the bowl (7) formed on the upper surface of the) it is mixed with the air forming turbulence whilst swirling.

However, in the case of a general premixed combustion chamber, the combustion chamber bowl diameter is enlarged, and the ignition delay effect is shown by the high injection pressure and EEG cooling, but the hydrocarbon emission is low due to the low compression ratio and the EG cooling. The tendency to increase is shown. Therefore, in order to solve this problem, it is possible to avoid fuel wall interaction by applying a small nozzle hole, and to reduce the hydrocarbon by increasing the diameter of the combustion chamber bowl. However, the above solution has a problem that may adversely affect the output delay and the maximum torque portion, not the pre-mixing region.

In addition, when the high-pressure fuel is sprayed into the combustion chamber in the part load (premixed combustion region), because of the spray pressure and droplet size, there is a problem that a lot of fuel that collides with the wall of the combustion chamber is generated a lot of unburned hydrocarbons. .

Therefore, the present invention has been made to solve the above problems, the fuel pressure and the droplet size of the fuel due to the collision of the combustion chamber wall with a lot of fuel for premixed combustion for reducing the generation of hydrocarbons due to unburned fuel The purpose is to provide an injector nozzle structure for a diesel engine.

The present invention as a means for achieving the above object,

In the combustion chamber of the diesel engine is formed in the injector for the injection of fuel in the lower side of the cylinder head, the piston injected in the cylinder liner so that the fuel injected from the injector is compressed and ignited,

Since the inner circumferences of the nozzles formed in the lower part of the injector in order to inject fuel into the combustion chamber are formed in the shape of an airfoil such as an airplane wing surface, the droplet size of the sprayed fuel can be reduced. .

1 is an enlarged view of a nozzle unit of an injector according to the present invention.

2 is a view showing a structure of a combustion chamber of a diesel engine to which an injector according to the present invention is applied.

3 is a view showing the configuration of a conventional diesel engine.

4 is a view showing the shape of a conventional injector nozzle.

※ Explanation of code for main part of drawing

20: injector

21: nozzle

22: needle

30: combustion chamber

31: piston

32: bowl

33: cylinder head

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an enlarged view of a nozzle part of an injector according to the present invention, and FIG. 2 shows a structure of a combustion chamber of a diesel engine to which an injector according to the present invention is applied, and reference numeral 20 denotes an injector according to the present invention. will be.

The general configuration of the injector 20 is formed as in the prior art, but the inner circumferential shape of the nozzle 21 formed below the injector 20 is not conventionally formed as a penetrating circle, and the inner circumferential surface of the plane It consists of an airfoil (Airfoil) shape such as.

That is, as shown in FIG. 1, the cross-sectional shape is gradually reduced and then expanded into a streamline shape, which is to reduce the droplet size of the fuel injected at high pressure. Further, this is to achieve effective premixed combustion by preventing the wall surface of the combustion chamber from being wetted by the injected fuel by making the spraying reach of the injected fuel small.

The lower end of the injector 20 formed as described above is fitted to the lower side of the cylinder head 33, and the nozzle 21 of the injector 20 is positioned above the combustion chamber 30 of the cylinder head 33. It protrudes slightly from the bottom surface. And the upper surface of the piston 31 is formed with a bowl 32 as in the prior art.

The operating state of the injector in which the nozzle is improved in shape as described above is as follows.

When the engine is started, the injector 20 is operated by the control of the electronic controller. That is, as the needle 22 reciprocates up and down in accordance with the fuel injection timing of the electronic controller, the nozzle 21 is opened and fuel is injected into the combustion chamber 30.

At this time, the nozzle 21 is formed in the air-foil streamline as described above, so that the droplet size of the fuel injected is smaller than in the case of the conventional cylindrical shape. As a result, the spraying distance of the injection fuel is reduced, and the phenomenon of wetting the wall surface of the combustion chamber by the fuel is prevented, and premixed combustion is effectively realized.

Therefore, when the high-pressure fuel is injected into the combustion chamber in the part load, which is a premixed combustion region, the spray pressure and the droplet size are reduced, and thus the generation of unburned hydrocarbons is significantly reduced compared with the conventional art.

According to the present invention configured as described above, the droplet size of the fuel injected into the combustion chamber at a high pressure is relatively reduced by changing the shape of the nozzle into the shape of an airfoil such as the wing surface of the plane, so that the amount of injection fuel that collides with the wall surface of the combustion chamber is increased. In addition to reducing the amount of unburned fuel has the advantage of reducing the generation of hydrocarbons.

Claims (1)

In the combustion chamber of the diesel engine is formed in the injector for the injection of fuel in the lower side of the cylinder head, the piston injected in the cylinder liner so that the fuel injected from the injector is compressed and ignited, Since the inner circumference of the nozzle 21 formed in the lower part of the injector 20 so that fuel is injected into the combustion chamber 30 is formed in the shape of an airfoil like an airplane wing surface, the droplets of fuel to be sprayed Injector nozzle structure of a diesel engine, characterized in that the size can be reduced.