JPS6032929A - Combustion chamber of direct-injection type internal- combustion engine - Google Patents

Abstract

PURPOSE:To improve the blue and white smoke and the irritating odor of exhaust gas at a low speed and a low output and improve the engine performance by forming a recess in a purse-like rotor shape in a direct-injection type internal-combustion engine having a recessed main combustion chamber at the top of a piston. CONSTITUTION:A main combustion chamber made with a recess 2 is provided at the top of a piston 1. This recess 2 is formed in a purse-like rotor shape with the diameter d2 of the upper portion made smaller than the diameter d3 of the bottom. A number of small recesses 4, corresponding to individual injection ports, having a semi-columnar shape with its upper portion expanded so as to be hit by the fuel spray F at a nearly right angle when the spray F is injected into this recess 2. Accordingly, the blue and white smoke and the irritating odor of exhaust gas at a low speed and a low output can be eliminated, and also the combustion performance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion chamber for a direct injection internal combustion engine having four main fuel chambers at the top of the piston.

Conventionally, the combustion chamber of a general direct-injection internal combustion engine has been of a toroidal type, which has a main combustion chamber of four parts 2 at the top of a piston 1, as shown in the side cross-sectional view of Fig. 1 and the plan view of Fig. 2. Then, for the same cylinder inner diameter, the ratio of the valley diameter, where the diameter of these four parts 2 is dl, is dz/D=0.45.
The inner wall surface of the four parts 2 is set to be inclined at about dθ=θ° to 7° with respect to the vertical direction.

However, even at low speed and low power of this internal combustion engine, the fuel spray F from each nozzle of the fuel injection valve 6 collides with the inner wall surface of the four parts 2 of the piston 1 even under compression conditions at the end of the compression stroke. At this time, since the wall surface temperature is low, fuel evaporation is delayed, and combustion is not completed completely, resulting in the generation of blue-white smoke and a pungent odor from the exhaust.

SUMMARY OF THE INVENTION Therefore, the present invention has been made to solve the above-mentioned conventional problems and to improve the performance of direct injection internal combustion engines by improving the blue-white smoke and irritating exhaust odor at low speeds and low power. It is something.

That is, the present invention provides a direct-injection internal combustion engine having a main combustion chamber with a concave portion at the top of the piston, in which the four parts are formed into the shape of an acrylic rotating body whose diameter at the top is smaller than the diameter at the bottom, and at which the fuel injection The fuel spray of the fuel injected from each nozzle of the valve is strange; each of the fuel sprays collides with the walls of the four colliding parts at almost right angles, forming a semi-cylindrical shape, and a small concave part with a widened top. It is characterized by this.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a side sectional view showing a combustion chamber of a direct injection internal combustion engine in an embodiment of the present invention, and FIG. 4 is a plan view of FIG. 3. It is.

First, as shown in Fig. 3, this direct injection internal combustion engine has a main combustion chamber of four parts 2 at the top of a piston 1, and these four parts 2 have a diameter d3 at the bottom and a diameter d2 at the top d3.
) It is formed in the shape of a revolving body centered on the center of the four parts 2 which have become smaller like dz.

Next, as shown in FIG. 4, when the fuel spray indicated by the arrow F injected from each nozzle of the fuel injection valve 6 is injected into this recess 2, it forms a semi-cylindrical shape such that it collides at approximately right angles, and A number of small recesses 4 whose upper portions are widened are formed in the four parts 2 in a number corresponding to each nozzle.

When providing the above-mentioned small recess 4, the injection angle θ4 of the fuel spray F injected at low speed and low power of the internal combustion engine is 10 to 20 degrees.
While forming a slightly larger small mouth portion 4, the fuel spray F
An appropriate distance 4 = 0.25 to 0.35 x D is maintained for complete combustion without adhering to the wall surface of the small recess 4.

To do this, we need to connect the point at distance l on the top surface of piston 1 and the fourth part 2.
A small semi-cylindrical recess 4 is formed by a cutting tool with a radius R4 between the bottom and a point with a diameter d3, and the wall surface of this small opening 4 shown in FIG. ,
For example, θ3 is formed at 90° to 95°.

In the combustion chamber of the present invention having the above configuration, the fuel spray F injected into the four parts 2 of the piston 1 is
When the force is low, as shown in Fig. 5, the swirl speed indicated by the arrow S is small, so it travels almost straight, but in the present invention, the small recess 4
is formed, the fuel will burn by the time it reaches the inner wall surface 4A of the small recess 4, and the flame at the tip of the fuel spray F will touch a little, but it will burn completely and will not emit blue-white smoke or irritating exhaust odor. .

Furthermore, when the engine is at high speed and under high load, the fuel spray F injected into the recess 2 is bent by the strong swirl indicated by the arrow S flowing into the recess 2, as shown in FIG. As shown in the figure, most of it collides with the groove-shaped portion on the inner wall surface of the edge portion 4.

Therefore, even during the above fuel injection, the piston 1 moves toward the top dead center, generating a stronger squish force than before on the upper surface of the piston 1, and the airflow combined with the swirl S is as shown in FIG. As shown in FIG. 6 and FIG.
Flows strongly diagonally downward to improve vaporization or mixing of air and particulate fuel.

Furthermore, a step 4B on the wall surface on the upstream side of the swirl S of the edge portion 4
gives turbulence to the air, and while giving strong turbulence to the fuel, air, and unburned gas at the step 4C on the downstream wall, it rotates within the cinquette-shaped four parts 2 formed on the rotating body, making it good. combustion.

Here, by forming the toroidal-shaped four parts 2 in which the diameter d2 of the opening is smaller than the diameter d1 of the conventional example shown in FIG.
The combustion chamber will be larger than the combustion chamber consisting of

Furthermore, when the piston 1 begins to descend from the top dead center, some of the unburned gas or the combustion gas containing carbon in the four parts 2 is reversed, so that it flows from the mouth part 4 to the upper surface of the piston 1 as shown in FIG. It leaks out.

In this case, for example, in the case of the fuel injection valve 6 having four nozzles as in this embodiment, the combustion gas spreads out in a fan shape through the four small recesses 4, causing mutual turbulence and causing the piston 1
The air utilization rate on the upper surface is improved, resulting in better combustion, and carbon generation is improved, resulting in better combustion even when the injection timing is delayed and the maximum pressure in the cylinder is lowered. The joint between the wall and the wall formed by d2+a3 may be slightly chamfered to reduce the heat load.

Therefore, in the combustion chamber of a direct injection internal combustion engine to which the present invention is applied, it is effective in eliminating blue-white smoke and irritating exhaust odor at low speeds and low power, and it also expands the squish force in the combustion chamber and improves fuel spray. It has the effect of improving combustion performance by improving mixing of air and the like.

In particular, the present invention can be effectively applied to direct injection diesel engines and the like.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a combustion chamber of a conventional direct injection internal combustion engine, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is a side view showing a combustion chamber of a direct injection internal combustion engine in Embodiment 1 of the present invention 4 is a plan view of FIG. 3, FIGS. 5 and 6 are enlarged plan views of the main part of the small recess shown in FIG. 4, and FIG. 7 is a perspective side view of the main part of the small recess shown in FIG. 6. 8 is a plan view showing the airflow on the top surface of the piston in FIG. 4 when the piston moves toward the top dead center, and FIG. 9 is a plan view showing the combustion gas on the top surface of the piston in FIG. 4 after the piston starts to descend. be. DESCRIPTION OF SYMBOLS 1... Piston, 2... Recessed part, 6... Fuel injection valve 14... Small recessed part, F... Fuel spray. Agent Patent Attorney Shin Ogawa - Patent Attorney Masaru Noguchi Patent Attorney Kazuhiko Saishita Figure 1 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] In a direct-injection internal combustion engine that has four main combustion chambers at the top of the piston, the concave part is formed in the shape of a rotating body with a smaller diameter at the top than at the bottom, and the fuel is injected from each nozzle of the fuel injection valve. A direct-injection internal combustion engine characterized in that each of the four wall surfaces on which the fuel spray collides is formed with a semi-cylindrical shape such that each fuel spray collides at a nearly right angle, and a small concave part with a widened upper part. combustion chamber of the engine.