JPS6275020A - Combustion device for diesel engine - Google Patents

Abstract

PURPOSE:To increase combustion efficiency and reduce exhaust density by providing an annular projection which projects out from the upper inner face of a nearly spherical combustion chamber toward the center of a piston. CONSTITUTION:A nearly spherical combustion chamber 4 is provided on a piston 3. One fuel valve 5 having one jet for forming one spray 6, is provided on a cylinder head, in a position near the outer periphery of the combustion chamber 4. An annular projection 9 projects out from the upper inner face of the nearly spherical combustion chamber 4 toward the center of the piston 3. Thereby, a spray can be developed toward a space on the central part of the combustion chamber 4 due to the controlling action of the moving direction of the spray by means of the projection 9, preventing the spray from flowing at a time out of the combustion chamber 4. Thereby, the combustion with high combustion efficiency, with low exhaust density, and with low noise, can be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a combustion device for a diesel engine.

[Conventional technology]

FIG. 5 is a sectional view showing a conventional single side injection type diesel engine. In the figure, 01 is the cylinder head, 02 is the cylinder liner, 03 is the piston,
04 is the combustion chamber, 05 is the fuel valve, 06 is the fuel spray, 07 is the gap between the piston and the cylinder head, and Sw is the air swirl. FIG. 6 is an explanatory diagram showing the movement of fuel spray.

In the above configuration, when the piston 03 rises and approaches the top dead center, fuel is injected from the fuel valve 05.

A fuel spray 06 is formed. At this time, considering that there is only one fuel spray, a strong air swirl Sw is generated during the air intake stroke to promote mixing of fuel and air. In addition, the combustion chamber has a spherical surface to spread the fuel spray as much as possible to increase the contact area with the air and improve the air-fuel mixture. Normally, the aim is to utilize this effect, that is, to utilize strong swirl and to widely disperse the fuel on the combustion chamber wall.

Setting the direction of injection has been used to obtain good combustion. In addition, in such a device, slow combustion is performed using a single spray, so combustion with low noise can be obtained.

[Problem that the invention seeks to solve]

The above has the following drawbacks.

The injected fuel collides with the combustion chamber wall and spreads.

It develops while being carried away by air swirls. At this time, the strong air swirl is used to cause the spray to swirl horizontally within the combustion chamber, and the intention is to make full use of the air within the combustion chamber, but in actual equipment it is necessary to supply fuel within a specified period. The nozzle area of the fuel valve cannot be made small, so the penetration force of the spray is too strong relative to the air swirl. In addition, since there are structural restrictions on the fuel valve settings in the injection direction, it is difficult to achieve a completely horizontal injection direction, and the spray has a vertical (downward) component.

For these reasons, after the fuel spray collides with the wall, it is not sufficiently rotated in the horizontal direction by the air swirl, but is only controlled by the wall to maintain its direction of motion.)
2. Dispersion is also not sufficient, and the gas flows in clumps, and as shown in FIG. 6, the gas flows out of the combustion chamber. The spray that has flowed out of the combustion chamber enters the gap 07 between the cylinder head 01 and the piston 03 in FIG. 5, and air introduction is obstructed.

Also, quenching of the flame occurs.

As described above, conventional devices cannot sufficiently utilize the air stored in the combustion chamber, resulting in a decrease in air utilization rate, deterioration in combustion efficiency, and increase in exhaust gas concentration.

[Means for solving problems]

The purpose of the present invention is to improve the dispersion of fuel within the combustion chamber and control the movement of fuel spray, thereby increasing the air utilization rate and achieving combustion with high combustion efficiency and low exhaust gas concentration. The purpose of the present invention is to provide a combustion device capable of carrying out the above-mentioned combustion, and its features are that the piston has a substantially spherical combustion chamber, and the cylinder head has a single spray located near the outer periphery of the combustion chamber. In a direct injection diesel engine having one fuel valve with one nozzle opening, an annular protrusion protruding from the upper inner surface of the approximately spherical combustion chamber toward the center of the piston is provided. Melt.

[Effect]

In this case, the movement direction control effect of the spray by the protrusion allows the spray to develop toward the center of the combustion chamber, thereby preventing the spray from flowing out of the combustion chamber all at once.

〔Example〕

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

FIG. 1 is a plan view showing a combustion chamber of one embodiment according to the present invention;
Figure 2 is a cross-sectional view taken along the ■-■ arrow in Figure 1, Figure 3 is an explanatory diagram showing the development of spray when it collides with a protrusion, and Figure 4 is an explanatory diagram showing the movement of spray within the combustion chamber. be.

4 in FIGS. 1 and 2 indicates a substantially spherical combustion chamber.

Reference numeral 9 in FIGS. 2 and 3 indicates a projection shaped like an eave at the upper part of the combustion chamber 4 at right angles to the axis. 6 in FIG. 3 indicates the spray, and the solid arrow indicates the direction of its movement.

In Fig. 4, 3 is a piston, 4 is a combustion chamber, and 5 is a fuel valve.

Reference numeral 6 indicates a fuel spray, and reference numeral 9 indicates a protrusion according to the present invention.

The operation in the case of the above configuration will be described.

The protrusion 9 according to the present invention allows the spray to develop toward the central space of the combustion chamber by controlling the movement direction of the spray as shown in FIG.

It is possible to prevent the spray from flowing out of the combustion chamber all at once.

〔Effect of the invention〕

In conventional devices, the penetration force of the spray is strong compared to the strength of the air swirl, and the injection direction has a vertically downward component, so the spray travels in the direction of injection in a lump, and - air is combusted. The air flowing outside and stored in the combustion chamber cannot be fully utilized, which may lead to deterioration in combustion efficiency and increase in exhaust gas concentration. To improve this, it is necessary to keep the spray inside the combustion chamber for as long as possible.

By providing a protrusion on the inner surface of the upper half of the combustion chamber as in the present invention, the spray that has developed while drawing in air on the wall surface collides with the protrusion. When the spray collides with the protrusion, as shown in Figure 3, the spray is rolled up into space and moves in the direction shown by the solid arrow, and the spray continues to develop in the direction in which it had developed up to that point, as shown in the direction of the dashed arrow. do not.

The present invention attempts to change the direction of spray movement by utilizing this characteristic, and as shown in Figure 4, the spray changes its movement toward the spatial direction of the center of the combustion chamber by colliding with the protrusion, and is caused by a strong air swirl. Perform a swirling motion within the combustion chamber while thoroughly mixing.

This prevents the spray from flowing out of the combustion chamber all at once and extends the time it stays in the combustion chamber, improving air utilization. Furthermore, the time at which the spray flows out of the combustion chamber can be delayed, and the spray can flow out after the gap between the piston and the cylinder head has become sufficiently wide, so that quenching of the flame can also be prevented.

As described above, according to the present invention, combustion with high combustion efficiency, low exhaust gas concentration, and low noise can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a combustion chamber of one embodiment according to the present invention;
Fig. 2 is a sectional view taken along the arrow ■-■ in Fig. 1, Fig. 3 is an explanatory diagram showing the development of the spray when it collides with a protrusion, Fig. 4 is an explanatory diagram showing the movement of the spray in the combustion chamber, FIG. 5 is a sectional view showing a conventional single side injection type diesel engine, and FIG. 6 is an explanatory diagram showing the movement of fuel spray. 3...Piston, 4...Substantially spherical combustion chamber, 5...
Fuel valve, 6...Fuel spray, 9...Protrusion. Figure 3 3111. Piston 4...Combustion chamber 5...Fuel valve 9...Protrusion No. 4 Figure 5

Claims (1)

[Claims] 1. Direct-injection diesel having a piston having a substantially spherical combustion chamber and a cylinder head having one fuel valve with one nozzle located near the outer periphery of the combustion chamber to form one spray. A combustion device for a diesel engine, characterized in that the engine is provided with an annular projection projecting from the upper inner surface of the substantially spherical combustion chamber toward the center of the piston.