JPS602491B2 - direct injection diesel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a direct injection diesel engine.

More specifically, the formation of a mixture of fuel and air in the combustion chamber and the development of a combustion flame are controlled to be uniform;
Therefore, the present invention relates to a direct injection diesel engine that can contribute to increased output and reduced smoke. [Sub-chassis technology] The deep-dish combustion chamber of a direct injection diesel engine has a combustion chamber diameter 4 mm larger than the piston diameter, so at the end of the piston compression stroke there is a gap between the combustion chamber and the air gap. A strong forced air flow, or squish, is created, and after top dead center, a reverse squish is created, where the flow is in the opposite direction.

Furthermore, if an intake air swirl is provided, it will be magnified several times when the piston is at top dead center. The swirl given at this initial stage is called cylinder swirl.
The latter enhanced swirl is called a bowl swirl.
These air flows such as squish, reverse squish, and swirl have an important influence on the formation and combustion of air-fuel mixture, and ideal combustion can be achieved by appropriately controlling and balancing these. However, in combustion in a deep-dish combustion chamber whose shape is circular when viewed from the top of the subordinate piston, these air flows are not ideally controlled, resulting in uneven fuel distribution and insufficient combustion performance. The disadvantage is that it is not fully developed. In other words, in a conventional direct injection diesel engine with a deep-dish combustion chamber, the fuel distribution within the combustion chamber is relatively uniform, but the fuel distribution in the top gap is not uniform and may be incomplete. This causes smoke generation due to combustion and a decrease in output. The problem of swirl in combustion is to form a mixture from the fuel injected from the injection nozzle and air, and to distribute it uniformly in the circumferential direction within the combustion chamber.

The role of the reverse squish in combustion is to forcefully send the burnt to unburned mixed gas in the combustion chamber to the top gap when the piston begins its downward stroke, where it comes into contact with fresh air and burns. In other words, the fuel within the combustion chamber is distributed to the top gap. However, in conventional deep-dish combustion chambers with a circular shape when viewed from the top of the piston, a portion of the spray from the injection nozzle adheres to the circumferential wall of the combustion chamber in the form of a film, which evaporates and burns. Since fuel cannot be deposited uniformly in the circumferential direction of the combustion chamber wall, the distribution of the fuel carried out to the top gap by the reverse squish will inevitably not be uniform. Additionally, if the combustion chamber is eccentric from the center of the injection nozzle, the spray distance from each injection nozzle with multiple inlets to the combustion chamber wall will be slightly different, resulting in a change in the amount of adhering fuel, resulting in the opposite effect. The distribution of fuel carried out by the squish is also not uniform.In this way, in the case of a secondary deep-dish combustion chamber, the fuel distribution within the combustion chamber is not uniform because the bowl swirl inside the chamber is amplified. Even if it were possible to achieve this, it would not be possible to make the top gap uniform in the circumferential direction because the cylinder wall would be widened and there would be no cylinder swirl. A combustion chamber is known in which the upper closed diameter is smaller than the lower closed diameter.

Compared to conventional deep-dish combustion chambers, this combustion chamber has a stronger reverse squish that flows out from the combustion chamber toward the top surface of the piston, which improves the mixing of fuel and air to some extent. It is not possible to change the cylinder swirl and bowl swirl, and therefore the problems of the conventional deep-dish combustion chamber have not been solved. Furthermore, the upper shape of the combustion chamber is made circular or square,
The combustion chamber with a rectangular lower part is manufactured by Tokusaki Showa 49-72508.
proposed by No.

This method injects the fuel mist from the nozzle into the square section at the bottom of the combustion chamber. In this case, small vortices are created at the corners of the lower square combustion chamber, concentrating the fuel spray at the corners. Although it is possible to promote mixture formation by
On the other hand, if the lower part of this system is square, there is a problem in that the bowl swirl, which plays an important role in mixing fuel and air, is attenuated. As a result, the mixture formation was only slightly better than in the conventional deep-dish combustion chamber. Furthermore, with this method, the air-fuel mixture concentrated in the corners of the lower rectangular combustion chamber becomes stagnant in the corners, preventing it from encountering new air necessary for combustion, which prevents sufficient combustion performance. The disadvantage is that it cannot be fully demonstrated.・[Objective of the Invention] The object of the present invention is to eliminate the above-mentioned conventional drawbacks, make it possible to equalize fuel distribution in both the combustion chamber and the top gap, and reduce smoke and improve output. The objective is to provide a direct injection diesel engine that makes it possible.

[Structure of the invention]

A direct injection diesel engine of the present invention which achieves the above object is a direct injection diesel engine which has a combustion chamber at the top of the piston and faces a fuel injection nozzle having a plurality of warm ports corresponding to the combustion chamber. The lower part of the combustion chamber is circular, the upper entrance part is polygonal, and each side of the upper polygonal opening □ is located inward than the green part of the lower circular part. The corner portion of the opening □ portion of the upper polygonal shape is at least flush with the edge of the lower circular portion, or if it is located inward than the tread portion, and the intake boat of the cylinder head is arranged so that the corner portion of the opening □ portion of the upper polygonal shape is at least flush with the edge of the lower circular portion. While giving a swirl to the intake air, the fuel mist from the fuel injection nozzle is injected toward the circular part at the bottom of the combustion chamber near the corner of the upper polygonal opening, so that the false fuel is removed. This is characterized in that each side of the upper opening is located above the portion where the fluid flows due to the swirl and reaches the combustion chamber wall.

[Example] Hereinafter, embodiments of the present invention shown in the drawings will be specifically explained.

FIG. 1 is a longitudinal sectional view of a direct injection diesel engine showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line 1-1 in FIG.

Moreover, FIG. 3 is a cross-sectional view showing the fuel concentration distribution of the air-fuel mixture in a conventional diesel engine. Figures 1 and 2
In the figure, 1 is a cylinder, and a piston 2 is iron-coupled to this cylinder 1 and reciprocates up and down.

A combustion chamber 3 is provided at the top of the piston 2. The combustion chamber 3 has a circular lower part and a polygonal upper opening.

In the embodiment, the combustion chamber 3 is constructed by fixing a squish control plate 4 having a polygonal opening □ to the upper part of a lower circular part. Reference numeral 5 denotes an injection nozzle mounted on the upper part of the cylinder. This injection nozzle 5 has four holes for fuel injection, and injects fuel in all directions within the combustion chamber 3.

Further, the injection nozzle 5 is provided eccentrically by a distance X with respect to the combustion chamber 3. In the illustrated example, as shown in FIG. 2, the squish control plate 4 has a rectangular closed part corresponding to the temperature of the injection nozzle 5, and each side of the open part is aligned with the lower circular part. Located inward from the edge and its opening □
The corners of the squish control plate 4 are formed such that the corner portions thereof are at least flush with the edge of the lower circular portion or located inward from the twill portion, and the lower combustion chamber is located on each side of the closed portion of the squish control plate 4 and at each corner portion. The distance L from the side wall and its dimensions are set to be different from each other.

Further, 6 in FIG. 1 is the top gap. Next, the effects of the present invention will be described.

The piston 2, which has the combustion chamber at the top, enters the upward stroke, and before the top dead center, fuel mist is ejected from the injection nozzle 5 into the upper polygonal shape □
The fuel is injected toward the lower circular part of the combustion chamber 3 near the corner of the combustion chamber 3. Here, the swirl generated by the intake boat of the cylinder head is slightly attenuated by the upper square part on the way to the lower circular part of the combustion chamber 3;
In the process of meeting the fuel injection and forming an air-fuel mixture in the lower circular part of the combustion chamber 3, there is little swirl attenuation (because the lower part is circular).
Moreover, when the swirl encounters resistance at the upper square part, a small vortex is generated at the corner, and this vortex is further sent to the lower part of the combustion chamber by the forward squish, so the swirl further promotes mixture formation. become. That is, in the present invention, the formation of air-fuel mixture is promoted by reducing swirl attenuation in the lower circular portion of the combustion chamber and by generating small vortices at the corners of the upper polygonal portion. Next, when the piston 2 completes its compression stroke and enters its downward stroke from top dead center, a reverse squish as shown by arrow A in FIG. 1 is created, and the shilling swirl shown by arrow B in FIG. A bowl swirl shown by arrow C is formed. Therefore, the fuel sprayed from the four mouths of the injection nozzle 5 flows in the swirl direction by the bowl swirl C in the combustion chamber 3, but in this case, the squish control plate 4 is not provided as in the present invention. In the case of a conventional deep-dish combustion chamber, the fuel atomized from the four lights □ of the injection nozzle 5 flows in the swirl direction by the bowl swirl C in the combustion chamber 3, as shown in FIG. From there, it is ejected as it is toward the top gap 6 by the reverse squish A.

Therefore, in the top gap 6, there are four ○ portions where the air-fuel mixture is highly concentrated (the blown out fuel is in the bowl swirl C).
The part that was flowed in the swirl direction by
In either case, uneven distribution of fuel will occur. In FIG. 3, the dotted line indicates the direction of the fuel lamp, and the dashed line indicates the upper entrance in the present invention. In the present invention, as shown in FIGS. 1 and 2, and as shown in FIG. 3, the squish control plate 4 is provided at the upper part of the lower circular part of the combustion chamber 3. In this squish control plate 4, the distance between the part corresponding to the E part where the fuel distribution becomes thinner and the inner wall of the lower circular part is reduced by 4 mm to make it easier for the fuel to blow out, and also to make the fuel distribution more concentrated. The distance L between the portion corresponding to the portion D and the inner wall of the lower circular portion is increased to suppress the outflow of fuel.

In this way, the fuel can be easily ejected from the part where the distance is short, and the fuel can be easily ejected from the part where the distance is long.
By suppressing the discharge of fuel from the portion due to reverse squish, the fuel distribution in the top gap 6 can be made uniform. In addition, since the injection nozzle 5 is located at an angle of x with respect to the lower combustion chamber 3, the dimensions of each side L and each corner throat of the upper quadrangular entrance part are changed, and the fuel distribution in the top gap part 6 is changed. It is designed to equalize the In the above embodiments, the squish control plate has a rectangular shape as the upper part of the combustion chamber, but it can be arbitrarily set to any shape such as triangular, pentagonal, hexagonal, etc. depending on the temperature of the injection nozzle.

〔Effect of the invention〕

As mentioned above, the direct injection diesel engine of the present invention has the following features:
In a direct injection diesel engine, a combustion chamber is provided at the top of the piston, and a fuel injection nozzle with a plurality of openings faces the combustion chamber. is configured in a polygonal shape, each side of the entrance part of the upper polygonal shape is located inward than the twilling part of the lower circular part, and the corner part of the closing part of the upper polygonal shape is
The lower circular part is at least flush with the crest of the lower circular part, and is located inward from the rim of the lower circular part, and the intake boat of the cylinder head gives a swirl to the intake air in the combustion chamber, and the fuel light mist from the fuel injection nozzle is , the fuel is injected toward the circular part at the bottom of the combustion chamber near the corner of the upper polygonal entrance part, and an upper closure is provided at the upper part of the part where the fuel mist is flowed by the swirl and reaches the wall of the combustion chamber. Since each side of the upper polygonal Sekiguchi part is positioned inwardly, the fuel can easily be ejected by reverse squish from near the corner where the green part of the upper polygonal Sekiguchi part is small. It is possible to suppress the discharge of fuel due to reverse squish from each side of the portion where the edge of the closed portion is located largely inward.

Therefore, each side is positioned above the part where the mist fuel is flowed by the swirl and reaches the combustion chamber wall to suppress the removal of fuel from that part, and the area near the corner is placed between these parts. By positioning the fuel to make it easier to eject fuel, it is possible to control the fuel distribution in the gap due to reverse squish to be uniform, and ideal air usage for complete combustion can be achieved. It's about being able to do something.

Therefore, according to the present invention, it is possible to provide a direct injection diesel engine that can reduce smoke due to incomplete combustion and improve output.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a direct injection diesel engine showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line 1-1 of FIG. FIG. 3 is a cross-sectional view showing the fuel concentration distribution of the air-fuel mixture in the subordinate diesel engine. 1...Cylinder, 2...
Piston, 3... Lower combustion chamber, 4... Squish control plate, 5
...Injection nozzle, 6...Top gap, A...Reverse squish, B...Cylinder swirl, C...Ball swirl. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a direct injection diesel engine that has a combustion chamber provided at the top of the piston and faces a fuel injection nozzle having a plurality of injection ports corresponding to the combustion chamber, the lower part of the combustion chamber is circular and the upper opening is is configured to have a polygonal shape, each side of the upper polygonal opening is located inward from an edge of the lower circular part, and a corner of the upper polygonal opening has at least the The cylinder head is positioned flush with or inward from the edge of the lower circular part, and the intake port of the cylinder head gives a swirl to the intake air in the combustion chamber, and the fuel spray from the fuel injection nozzle is directed to the upper part. The injection is made toward the circular part at the bottom of the combustion chamber near the corners of the polygonal opening, and each side of the upper opening is placed above the area where the atomized fuel is flowed by the swirl and reaches the wall of the combustion chamber. A direct injection diesel engine characterized by the fact that it is located at