JPS603311Y2 - Combustion chamber of direct injection diesel engine - Google Patents

Description

[Detailed description of the invention] This invention relates to improving the combustion chamber of a direct injection diesel engine.
Specifically, the present invention relates to a combustion chamber configuration in which a spiral guide vane is provided at the bottom of the combustion chamber to correct the rotation trajectory of the swirl and agitate the air-fuel mixture in order to completely burn the air-fuel mixture.

A direct-injection diesel engine uses a fuel injection valve to inject fuel into compressed, high-temperature, high-pressure air, and the temperature of this air causes spontaneous ignition, and the fuel is first atomized in the combustion chamber. It is mixed into the air, and the device is simple, but internal combustion types include those that have a carburetor and create a mixture of air and fuel in advance and inject it into the combustion chamber, and those that create the mixture in a pre-combustion chamber. It has been pointed out that the disadvantage is that the uniformity of the air-fuel mixture is inferior to that of engines.

The reason for this will be explained with reference to FIG. The particulate fuel ejected from the fuel injection valve 3 travels along the nozzle center line 4 and is injected toward the side wall 5, so that the concentration of fuel gas is very high near the side wall 5 and thin at the center. This results in so-called uneven distribution, which is the cause of non-uniformity of the air-fuel mixture.

As a known means for solving such problems, for example, an annular deflection section is stepped approximately midway between the peripheral wall defining the combustion chamber and the conical protrusion provided at the center of the combustion chamber. Combustion chamber of a diesel engine designed to deflect and disperse injected fuel (see Utility Model Publication No. 46-32961)
A combustion chamber is known that is equipped with a fuel collision plate that allows most of the fuel jet injected from the nozzle to collide with the fuel jet and change the direction of its diffusion (see Japanese Utility Model Publication No. 1864/1983). Since such known means directly collides the sprayed fuel with the annular deflector or the fuel collision plate, the collision delays the evaporation of the fuel and insufficient evaporation occurs, resulting in incomplete combustion, which is particularly noticeable during idling. It has the disadvantage of producing blue smoke, white smoke, and bad odors.

On the other hand, there is a combustion chamber in which a plurality of blades are provided extending radially from the approximate center of a cavity formed at the top of the piston, and each of the blades is provided with a slope portion that is inclined with respect to the plane of the top of the piston. 53-22907, the blade described in this publication has a smaller radius than the cavity, and there is a gap between it and the inner wall of the cavity that allows the swirl to pass through, so the outer periphery has the strongest swirl. It is not possible to use swirl or generate a three-dimensional stirring flow including the flow in the sliding direction of the piston.
There was a problem that the disturbing effect of the sprayed fuel was not sufficiently exerted, and there remained room for further improvement in this respect.

The purpose of the present invention is to eliminate the disadvantage of incomplete combustion inherent in the conventional technology as described above, and to provide a diesel engine that does not cause air pollution. A spiral guide vane is disposed on the bottom of the combustion chamber to be formed, and has the function of disturbing and attenuating the so-called swirl, and corrects the rotational trajectory of the swirl in a certain direction so that the swirl flowing at the bottom of the combustion chamber is directed toward the center or It is characterized by a structure that increases the uniformity of the air-fuel mixture by providing directionality toward the side wall, thereby generating upward or downward airflow within the combustion chamber, and thereby stirring the air within the combustion chamber. In the room, the piston only makes a rotational movement around the center,
Complete combustion is made possible by giving an active stirring function to the swirl, which did not contribute to stirring the air-fuel mixture.

Hereinafter, embodiments of the present invention will be described with further reference to the accompanying drawings starting from FIG.

Figure 2A is a plan view of one embodiment, and the opening in the figure is I-
It is an I sectional view.

In FIG. 2, the combustion chamber 7, which is recessed from the top plane 6 of the cylinder 1, has a side wall 5. A conical projection 1 defined by the bottom surface 9 and bulging upward from the bottom surface 9 at the center of the bottom surface 9.
6, and a bottom surface 9 centered on the conical protrusion 16.
It has a protruding guide vane 10 that bulges further upward.

The guide vane 10 has a spiral shape around the piston center line 2, and the twisting direction of the spiral is opposite to the direction of rotation of the swirl indicated by the arrow 11, and does not completely prevent the rotation of the swirl. , and a nozzle center line 4 indicating the fuel injection direction of the fuel injection valve 3 so that the fuel spray does not directly collide with the fuel spray.
and the combustion chamber side wall 5, including the intersection 12 of the piston center line 2
It is provided below a plane 13 perpendicular to .

Since the present embodiment is constructed as described above, the swirl that flows in from the intake port and flows above the combustion chamber is not inhibited from rotating separately, so it rotates at a constant speed on an orbit of a constant radius, but The swirl flowing at the bottom collides with the guide vane 10, corrects its trajectory according to its twisting direction, and moves along the guide vane 10 as shown by the arrow 14 to the side wall 5.
This creates an airflow that flows toward the center.

When such a flow occurs, the air near the side wall 5 flows toward the center, and to compensate for this flow, a downward air current shown by an arrow 17 is generated near the side wall.

Due to this air flow, the concentrated fuel gas near the side wall 5 is mixed with the lean gas in the center, making the mixture uniform and achieving complete combustion.

Also, among the swirls that rotate in the combustion chamber that flow in from the intake port, those that rotate at the top of the combustion chamber maintain a constant rotational speed, but the swirls that rotate at the bottom of the combustion chamber collide with the swirl stirring protrusions and are attenuated. Due to the difference in swirl rotational speed between the upper and lower layers, countless small air vortices are generated at the boundary between the upper and lower layers, further promoting homogenization of the air-fuel mixture.

In FIG. 3 A9 showing another embodiment, the guide vane 101
The direction of the twist is determined to be the same direction as the direction of the arrow 11 indicating the direction of rotation of the swirl.

Therefore, the swirl swirling around the bottom of the combustion chamber collides with the guide vane 101 and is converted into a flow from the center toward the side wall 5 as shown by the arrow 141.

This flow 141 hits the side wall 5 and becomes an ascending air flow 171, so that the fuel gas existing in the center is mixed with the lean gas in the side wall, and the air-fuel mixture becomes homogenized.

In this case as well, the stirring of the air-fuel mixture caused by the speed difference of the swirl in the upper part of the combustion chamber is the same as in the case of FIG. 2.

Furthermore, since the airflow from the center of the combustion chamber toward the side wall 5 or from the vicinity of the side wall 5 toward the center of the combustion chamber as described above circulates within the combustion chamber, it naturally causes a downward or upward airflow in the center, and the air-fuel mixture uniformity is promoted.

The direction of twisting of the guide vanes 10, 101 as described above can be selected to be optimal depending on the penetration force of the spray, etc. in combination with the injection system, and the number of guide vanes makes the vortex state for each spray the same. In order to achieve this, it is desirable to match the number of nozzles of the combustion injection valve, but if it is necessary to vary the state of the vortex for each spray, the number may be different from the number of nozzles.

As described above, the present invention modifies the rotational trajectory of the swirl flowing at the bottom of the combustion chamber using guide vanes to generate airflow from the center of the combustion chamber to the side wall or from the side wall to the center, and further from the upper layer of the combustion chamber. Combustion in direct-injection diesel engines with the same function as the pre-combustion chamber, which aims to homogenize the air-fuel mixture by creating airflow toward the lower layer or from the lower layer to the upper layer, and uses a powerful vortex to homogenize the mixture. This is what I gave to Muro.

Therefore, it is fundamentally different from the method in which the sprayed fuel is directly collided with the combustion chamber wall etc. to disperse the spray, so it does not cause deterioration of the exhaust concentration due to poor combustion vaporization, and therefore blue smoke, blue smoke, etc.
It can prevent the generation of pollution sources such as white smoke and bad odors.
While maintaining the advantages of a direct injection internal combustion engine, such as ease of manufacturing the cylinder head, no need for an electromagnetic coil, and high thermal efficiency, it is a low-pollution and inexpensive fuel due to complete combustion similar to when a carburetor or pre-combustion chamber is installed. However, it has advantages such as economy, which makes it possible to use it even in the same environment.

In addition, since the swirl stirring protrusion is provided below the area where the atomized fuel is injected from the fuel injection valve and advances inside the combustion chamber, the atomized fuel is not directly injected onto the spiral guide vanes, thereby reducing the exhaust concentration. Inconveniences that may lead to deterioration are avoided.

Furthermore, experiments have shown that in the present invention, the active vortices generated by the spiral guide vanes are particularly effective in forming a mixture of air and fuel, and as a result, even if the injection timing is delayed, the exhaust concentration does not deteriorate. A reduction in NOx was observed by delaying the injection timing, and an improvement in combustion noise was also observed due to a reduction in the maximum in-cylinder noise.

[Brief explanation of drawings]

Fig. 1 shows a conventional combustion chamber, A is a plan view thereof, the mouth is a central sectional view, and Figs. 2 and 3 each show an embodiment according to the present invention; It is each II sectional view. 3...Fuel injection valve, 4...Central line, 5...Combustion chamber side wall, 9...Combustion chamber bottom surface 10...・Spiral guide vane, 12...
Intersection, 13...plane, 18...bottom.

Claims (1)

[Scope of utility model registration request] In a direct injection diesel engine, a swirl stirring peak-shaped guide vane 10 extends radially upward from the bottom surface 9 of a combustion chamber 7 formed at the top of the piston, with the guide vane 10 centered on the piston. The guide blades 10 are curved in a certain direction from the side wall 5 to the side wall 5 of the combustion chamber, and extend in a spiral shape in plan so that the ridge line maintains a required height and continues to the side wall 5 of the combustion chamber. A combustion chamber for a direct injection diesel engine, characterized in that it is disposed below a plane 13 that includes an intersection 12 between a nozzle center line 4 of a fuel injection valve 3 and a combustion chamber side wall 5 and is perpendicular to a piston center line 2.