KR20020053242A - Swirl chamber type combustion chamber for diesel engine - Google Patents

Abstract

PURPOSE: A swirl chamber type diesel engine combustion chamber is provided to restrict harmful material among exhaust gas, and to prevent irregular combustion from partial load by modifying a main combustion chamber and a swirl chamber. CONSTITUTION: A combustion chamber of a swirl chamber diesel engine is composed of a sub combustion chamber assembly(20) having a sub combustion chamber(22) with a fuel collision part(26), a vortex guide part(28) and an inclined connecting passage; and a piston(30) having a main combustion chamber(32) including a trench part(34) and a clover part(36) connected to the connecting passage. The linear section is formed in the vortex guide part to reduce vortex. The squareness of the corner between the trench part and the clover part is reduced to decrease the volume ratio of the sub combustion chamber, and the squareness of the corner between the clover part and the upper part of the piston is decreased. Discharge of harmful material is prevented with improving combustion efficiency.

Description

Vortex chamber type diesel engine combustion chamber {SWIRL CHAMBER TYPE COMBUSTION CHAMBER FOR DIESEL ENGINE}

The present invention relates to a vortex chamber type diesel engine combustion chamber, and more particularly, a vortex chamber type which can suppress the generation of harmful substances contained in the exhaust gas by reducing the shape of the sub-combustion chamber and the main combustion chamber and reduce the phenomena at partial load. Relates to a diesel engine combustion chamber.

In general, in the case of medium and large diesel engines, the time required for the formation of the mixer is increased, and thus, fuel injection alone allows sufficient contact with air. However, in the small and high-speed diesel engines, combustion may be completed in a short time without the help of air vortex. Can't. There are several types of combustion chambers of such diesel engines, which are classified into direct injection chamber type, preburn chamber type, vortex chamber type, air chamber type, etc., except for the direct combustion chamber type, the remaining combustion chamber is required. In particular, the vortex chamber combustion chamber injects and combusts fuel in an air vortex generated in the subcombustion chamber (vortex chamber) by a compression stroke. Hereinafter, in this specification, a swirl chamber combustion chamber is described.

1 is a view showing the internal structure of a conventional vortex chamber diesel engine combustion chamber. Here, the structure of the subcombustion chamber (vortex chamber) is shown mainly.

In FIG. 1, the subcombustion chamber assembly 2 is separately assembled to the cylinder head 1 to provide the subcombustion chamber 2a, and the main combustion chamber 3a is formed on the upper surface side of the piston 3. In the upper cylinder head 1 of the subcombustion chamber 2a, an injection nozzle 4 is inclined so as to inject fuel into one wall surface of the subcombustion chamber 2a so as to be inclined. (5) is mounted. This glow plug 5 is provided because the temperature of the starting or low-speed combustion chamber is low. At the lower end of the subcombustion chamber 2a, a connecting passage 2b through which air is introduced from the main combustion chamber 3a is inclined. This connecting passage 2b is mainly provided in the tangential direction of the subcombustion chamber 2a. The coolant passage 1a is formed around the subcombustion chamber 2a.

The vortex chamber type combustion chamber provided as described above forms a strong vortex like an arrow when the compressed air flowing from the main combustion chamber 3a flows to the subcombustion chamber 2a through the connection passage 2b during the compression stroke. At this time, fuel is injected from the injection nozzle 4, and almost combustion is performed in the subcombustion chamber 2a.

The conventional vortex chamber combustion chamber is Ricardo's Comet type, in particular the shape of the subcombustion chamber assembly 2, as shown in Fig. 2, in a straight cross section where the fuel injected from the injection nozzle 4 collides. It may be divided into a fuel impingement part 2 of the form and the eddy current induction part 2d having a curved shape.

Since the vortex induction part 2d of the sub-combustion chamber assembly 2 having such a structure has a curved shape, it can generate strong air vortices, but there is a problem that it is not easy to process and quality control is not easy during mass production. Due to the strong vortex generation, it is the cause of increasing the emission of nitrogen oxides (NO _x ) among the harmful components of the exhaust gas.

In addition, since the volume ratio (relative to the total combustion chamber volume) of the subcombustion chamber 2a is relatively large, the air utilization rate can be increased and the vortex generation can be helped, but the heat dissipation increases, so that the combustion is irregular for the partial load. Is generated to increase the emissions of hydrocarbons (HC).

In addition, since the air hole ratio (ratio of the cross-sectional area of the upper surface of the piston 3 to the nozzle cross section of the injection nozzle 4 of the subcombustion chamber 2a) is relatively high, it is connected when the combustion gas moves from the subcombustion chamber 2a to the main combustion chamber 3a. Since the loss of kinetic energy of the passage 2b is increased, the efficiency is reduced and the emission of carbon monoxide (CO) in the exhaust gas is increased.

Therefore, the present invention was created to solve the above-mentioned problems, an object of the present invention is to modify the shape of the sub-combustion chamber and the main combustion chamber to suppress the generation of harmful substances contained in the exhaust gas and to prevent the relief phenomenon of the partial load section. It is to provide a vortex chamber diesel engine combustion chamber that can be reduced.

1 is a cross-sectional view showing the internal structure of a typical vortex chamber diesel engine combustion chamber.

Figure 2 is a cross-sectional view showing the sub-combustion chamber portion of the vortex chamber diesel engine combustion chamber according to a conventional embodiment.

3 is a cross-sectional view showing a vortex chamber diesel engine combustion chamber according to an embodiment of the present invention.

4 is a cross-sectional view showing the top shape of the piston shown in FIG.

5 is a cross-sectional view taken along the line A-A of FIG.

※ Explanation of codes for main parts of drawing

20: combustion chamber assembly 22: combustion chamber

24: connecting passage 26: fuel collision

28: vortex induction part 30: piston

32: main combustion chamber 34: trench

36: clover

In the vortex chamber diesel engine combustion chamber according to the present invention for achieving the above object, the inner wall surface is composed of a fuel impingement portion and the vortex induction portion of the air, the sub-combustion chamber assembly is formed by the connecting passage inclined to the lower end to form a sub-combustion chamber In the vortex chamber diesel engine combustion chamber comprising a piston consisting of a trench portion and a clover portion in communication with the connecting passage forming a main combustion chamber, the vortex induction portion of the sub-combustion chamber assembly has a straight cross-sectional shape to reduce air vortex, In order to reduce the volume ratio of the subcombustion chamber, the corner portion R1 of the corner portion facing the trench portion and the clover portion may be reduced, and the squareness portion R2 of the edge portion facing the clover portion and the piston upper surface portion may be reduced.

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

3 is a cross-sectional view showing a vortex chamber diesel engine combustion chamber according to an embodiment of the present invention. FIG. 4 is a cross-sectional view illustrating a top surface of the piston illustrated in FIG. 3, and FIG. 5 is a cross-sectional view taken along line AA of FIG. 3.

In Fig. 3, reference numeral 20 denotes a sub-combustion chamber assembly, which is composed of an open cylindrical body that is narrowed in width and is combined with a hemispherical cylinder head 10 located thereon to form the sub-combustion chamber 22. That is, the connection passage 24 communicating with the main combustion chamber 32 of the piston 30 to be described later is formed on the bottom surface of the sub-combustion chamber assembly 20 to be inclined. The inner wall surface of the assembly 20 is a fuel impingement part 26 which is a portion where fuel injected from an injection nozzle not shown collides, and a vortex induction part for inducing vortices of air flowing through the fuel passage 24 ( 28). The shapes of the fuel impingement part 26 and the vortex induction part 28 are the same in the form of a straight cross section, and the whole forms a cylindrical shape whose width is narrowed downward. In particular, the shape change of the vortex induction part 28 makes it possible to relatively reduce the induction of air vortex compared to the conventional curved shape.

As described above, the vortex induction part 28 of the present embodiment has a straight cross-sectional shape unlike the conventional curved shape, so that the structure is simple and easy to manufacture, thereby facilitating quality control in mass production. In addition, since the low vortex is induced, the emission of nitrogen oxides (NO _x ) among the harmful components of the exhaust gas can be suppressed.

In addition, in this embodiment, the volume ratio of the sub-combustion chamber 22 to the total combustion chamber area is slightly reduced compared with the prior art. For example, when the conventional sub-combustion chamber volume ratio is 56.9%, it is preferable to reduce it to about 55.5%. This is to reduce the heat loss to the sub-combustion chamber (22). Therefore, the relief (shake) caused by the irregular combustion at the partial load is reduced, so the emission of hydrocarbon (HC) is reduced.

Reference numeral 30 denotes a piston, which communicates with the connection passage 24 of the subcombustion chamber assembly 20 to form a space forming the main combustion chamber 32. That is, as shown in FIG. 4, a trench 34 for directly guiding combustion gas from the sub-combustion chamber 22 through the connecting passage 24 is formed on the upper surface of the piston 30. A clover portion 36 for diffusing the combustion gas around the 34 is formed.

In the present embodiment, instead of slightly reducing the volume ratio of the sub-combustion chamber 22, the volume of the main combustion chamber 32 is increased. As shown in FIGS. 3 and 5, the trench part 34 and the clover part 36 are first shown. Expect the effect of increasing the depth of the trench 34 by reducing the squareness (R1) of the corner facing. This is to improve the guide action of the combustion gas of the trench 34. In addition, the depth of the clover portion 36 is increased by reducing the squareness R2 of the corners facing the clover 36 portion and the piston 30 upper surface portion. For example, it is preferable to reduce the volume ratio of the subcombustion chamber 22 as described above to 4.5 when R1 is 5 and 0.9 when R2 is 1.

Such deformations require that the total volume of the combustion chamber always be constant, so that a substantial deformation of the main combustion chamber 32 configuration, i.e. the dimensions of the diameter of the clover portion 36 or the total depth of the trench portion 34, is achieved in order to reduce the volume ratio of the subcombustion chamber. You should not make any changes that actually increase.

This embodiment increases the pore ratio, that is, the ratio of the top surface cross-sectional area of the piston 30 to the jet cross section of the injection nozzle (not shown) of the subcombustion chamber 22. This serves to reduce the kinetic energy loss of the connecting passage 24 when the combustion gas moves from the sub-combustion chamber 22 to the main combustion chamber 32 to increase efficiency and to reduce the emission of carbon monoxide (CO) contained in the exhaust gas.

Furthermore, increasing the compression ratio can solve the low combustion efficiency due to low vortices at low speed and low load.

According to the present invention described above, since particulate matter (C) contained in the exhaust gas, and carbon (CO) and hydrocarbon (HC) can be greatly reduced, the exhaust gas recirculation apparatus is used to recover the recycle gas that does not contain these harmful substances. In addition to increasing their utilization, they can also reduce the emissions of nitrogen oxides. In addition, the reduction of hydrocarbons can greatly improve the relief phenomenon in the low speed low load section.

Claims (1)

The inner wall surface is composed of a fuel impingement part and an air vortex induction part, and a connecting passage inclined at the lower end thereof is formed to form a subcombustion chamber, and a trench part and a clover part communicating with the connecting passage form a main combustion chamber. In the vortex chamber diesel engine combustion chamber including a piston, The vortex induction part of the subcombustion chamber assembly has a straight cross-sectional shape to reduce air vortex, and reduces the squareness (R1) of the corners facing the trench and the clover part so as to reduce the volume ratio of the subcombustion chamber, and Vortex chamber diesel engine combustion chamber, characterized in that to reduce the squareness (R2) of the edge facing the piston upper surface.