JPS5813072Y2 - Combustion chamber of direct injection diesel engine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a combustion chamber of a direct injection easel engine configured to actively generate swirl within the combustion chamber.

In a direct injection diesel engine, the intake passage is formed at a predetermined angle to create a swirl in the intake air flow taken into the cylinder.

This swirl enters the combustion chamber during the compression stroke and promotes evaporation and diffusion of the fuel injected into the combustion chamber.

In particular, an evaporative combustion easel engine injects fuel into the combustion chamber wall and evaporates it due to the temperature of the combustion chamber wall surface, which reduces the mixing of intake air and fuel within the combustion chamber and the propagation speed of the combustion flame. Swirl plays an important role in improvement.

However, the conventional combustion chamber structure of this method did not have a structure that actively mixed air and liquid fuel within the combustion chamber, so it was not sufficient in terms of combustion efficiency.

An object of the present invention is to provide a combustion chamber for a direct-injection easel engine that has a structure that actively swirls intake air that is forced into the combustion chamber during a compression stroke.

This will be explained in detail below using figures.

FIG. 1 is a schematic cross-sectional view showing a conventional combustion chamber structure, in which a combustion chamber 2 formed at the top of a cylinder 1 has an inner wall surface 3.
is approximately spherical.

The intake air taken in from the intake valve 4 causes a swirl S' in the cylinder 5.

When the piston 1 moves upward during the compression stroke, the swirl S' is forced into the combustion chamber 2 and maintains the swirl within the combustion chamber 2.

However, since the shape of the inner wall surface 3 is merely spherical, the evaporation and peeling effects, as well as the diffusion effect, of the fuel sprayed toward the inner wall surface 3 from the injection nozzle 6 are insufficient.

An embodiment of the present invention that improves the above drawbacks will be described below.

In FIG. 2, a cylinder 1 in which a piston 11 reciprocates
A cylinder head 13 is provided at the -L portion of 2, and an intake passage 14 is provided in the cylinder head 13.

An intake valve seat 15 is formed at the inner end of the cylinder 12 of the intake passage 14, and an intake valve 16 that controls opening and closing of the intake valve seat is provided.

A portion of the intake passage 14 near the intake valve seat 15 may be inclined with respect to the cylinder axis to create a swirl when intake air is drawn into the cylinder 12, or may be formed in a helical shape as shown in the figure. , the intake air is Shinonda 12
It is constructed along a substantially tangential direction of the inner wall surface of the.

A combustion chamber 17 is provided at the top of the piston, and a spiral groove 18 is formed on the inner wall of the side surface of the combustion chamber 17, and the depth direction of the groove 18 is the spiral radial direction.

The spiral radius of the groove 18 in the combustion chamber 17 is
The bottom 1 decreases toward the bottom 19 of the
It tapers towards 9.

Furthermore, the spiral direction of the groove] 8 is the same as that of the intake passage 14.
The direction is the same as the direction of the swirl of intake air caused by.

Furthermore, the cylinder head 13 is provided with a fuel injection nozzle 20 .

The operation of the present invention constructed as above will be explained below with reference to FIG.

Referring to FIG. 3A, first, when the piston 11 enters the intake stroke, the intake valve 16 separates from the intake valve seat 15, and intake air is drawn into the cylinder 12 through the intake passage 14.

The intake air causes a swirl S1 and rotates within the cylinder 12, and this swirl S1 is also transmitted into the combustion chamber 17.

Therefore, swirl S2 also occurs within the combustion chamber 17.

Next, referring to the port in FIG. 3, when the intake stroke ends and the piston 11 enters the compression stroke, the screws 1 to 11 move upward and the intake air in the cylinder 12 is forced into the combustion chamber. Ru.

In this case, the intake air in the cylinder 12 substantially maintains the swirl S1 during the intake stroke, and therefore is pumped into the combustion chamber 17 as a swirling flow.

The intake air forced into the combustion chamber 17 flows along the groove 18 to the bottom 1.
However, since the groove 18 is spiral and has the same spiral direction as the swirl S1, it is actively swirled within the combustion chamber 17 and a swirl is generated within the combustion chamber 17. S3 occurs.

This swirl S3 is stronger than the swirl S' in the known combustion chamber.

Next, when the fuel is injected from the fuel injection nozzle 20 and applied to the inner wall of the combustion chamber 17, the fuel is evaporated and separated by the high temperature of the inner wall of the combustion chamber 17 and the swirl S3, and is further spread to the entire area inside the combustion chamber 17. It will be spread.

As described above, according to the present invention, since a swirl is actively given to the intake air that is forced into the combustion chamber, it is possible to increase the combustion rate, and furthermore, to improve the air utilization efficiency by promoting the mixing of intake air and fuel. It is something that can be done.

In addition, according to the present invention, it is possible to obtain remarkable effects such as improved startability, reduced diesel black smoke, and increased output.

In addition, in the above-mentioned configuration, if the shape of the combustion chamber is tapered toward the bottom, not only will the swirl generated within the combustion chamber be made stronger, but also the air will be spread throughout the corners of the combustion chamber. This makes it possible to improve the utilization rate.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view showing an example of the combustion chamber of a conventional evaporative combustion diesel engine, Fig. 2 is a schematic cross-sectional view showing an embodiment of the present invention, and Fig. 3 A-9 shows the function of the present invention. It is a schematic diagram for explaining. 17: Combustion chamber, 18: Groove.

Claims (1)

[Scope of utility model registration request] This is an evaporative combustion type direct injection diesel engine, in which a spiral groove is formed on the inner side wall of the combustion chamber provided at the top of the piston, and the spiral radius of the spiral groove decreases toward the bottom of the combustion chamber. and a direction of the depth of the spiral groove is a spiral radial direction.