JP2501299Y2 - Combustion chamber of diesel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a combustion chamber and a fuel injection valve of a diesel engine.

[Prior Art] FIGS. 3 and 4 show typical examples of the arrangement of a combustion chamber and a fuel injection valve of a conventional direct injection type diesel engine. It will be described with reference to the drawings.

As shown in FIG. 3, in the conventional combustion apparatus, one cylinder-shaped combustion chamber 101a is arranged substantially in the center of the piston 101, and the fuel injection valve 103 provided in the cylinder head 102 has several injection holes. ,
Radial fuel spray from the upper center of the cylindrical combustion chamber 101a
104 is injected and ignited and burned.

In the conventional combustion apparatus, since the diameter of the combustion chamber is relatively large, the fuel spray 104 ignites before it collides with the wall surface 101b of the combustion chamber. At this time, since there is sufficient air around the flame, the flame spreads rapidly.

Next, the spray flame diffuses left and right along the combustion chamber wall 101b, collides with the adjacent spray flame, and returns toward the center of the combustion chamber and diffuses throughout.

Conventionally, a swirl SW (circle) in the circumferential direction is generated in the combustion chamber to promote combustion, but in this case, most of the fuel spray is made to flow downstream of the swirl SW, and the spray flame also goes downstream. Diffuse and rotate in one direction in the combustion chamber. At this time, the interference between adjacent spray flames is relatively small,
Combustion proceeds and ends until there is almost no micro diffusion between them.

[Problems to be solved by the device]

The diameter of the combustion chamber of the conventional direct injection diesel engine is 0.5 to 0.6 or more relative to the piston diameter, which is relatively large. Therefore, there is sufficient space until the fuel spray injected from the fuel valve arranged in the center of the combustion chamber collides with the wall of the combustion chamber,
Due to the presence of air, a rapid flame spread occurs after ignition,
The high temperature combustion causes generation of a large amount of nitrogen oxides in the early stage of combustion.

Further, in the latter half of the combustion, the fuel and the air are not uniformly mixed in the combustion chamber, so that there is a problem that black smoke is generated due to the air shortage in the extreme part and the fuel consumption is deteriorated. This is because in the conventional simple cylindrical shape, even if the fuel is simply injected from the center of the combustion chamber, the microscopic mixing of the fuel and air cannot be completely made uniform both temporally and spatially. .

An object of the present invention is to provide a combustion chamber of a diesel engine capable of performing relatively uniform combustion from the early stage to the late stage of combustion of the injected fuel.

[Means for solving the problem]

As a combustion chamber formed on the top of the piston, one large combustion chamber is arranged in the center and one small combustion chamber is arranged on the left and right of the large combustion chamber. Each combustion chamber has a circular planar shape, and the large combustion chamber and the left and right small combustion chambers are connected by a notched guide passage. The guide passages of the large and small combustion spaces are oriented so as to swirl in the outer peripheral direction of the large combustion chamber and have a planar cross-section that expands toward the large combustion chamber side.

As for the vertical cross section, the large combustion chamber has a wedge shape, and the small combustion chamber has a spherical shape with the upper part cut off. The guide passage between the large and small combustion chambers is joined at the upper part of each combustion chamber.

One fuel injection valve is provided in the cylinder head above the center of each small combustion chamber so as to inject fuel toward the small combustion chamber.

[Action]

When injected toward the small combustion chamber from several or one injection holes of the fuel injection valves arranged above the center of the two small combustion chambers, the fuel spray is dispersed along the spherical wall surface, and inside the small combustion chamber Immediately filled with fuel spray. Ignition is performed in this rich mixture state, but the rapid combustion in the initial stage is suppressed due to lack of air.

Next, from the small combustion chamber filled with the spray flame, the spray flame which is not completely burned is ejected into the large combustion chamber through the guide passage. At this time, the spray flames from the left and right small combustion chambers are ejected in the same direction as the direction of the swirl (swirl) given to the large combustion chamber so that they do not collide with each other in the outer peripheral direction of the central large combustion chamber at the same time. .

By doing so, the spray flame in the semi-combustion state ejected to the large combustion chamber is promoted to burn because there is sufficient air. Furthermore, by ejecting the swirl given to the large combustion chamber so as to utilize it, it becomes possible to continue and improve the mixing with air until the latter stage of combustion, and complete combustion can be measured.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view of the combustion chamber of the embodiment, and FIG. 2 is II-I of FIG.
It is I sectional drawing. In the figure, the combustion chamber provided at the top of the piston 1 has a large combustion chamber 1a at the center and spherical small combustion chambers 1b and 1c at the left and right sides thereof with the heads cut off. The large combustion chamber 1a and the small combustion chambers 1b, 1c have guide passages 1d, 1e
Are joined by. The guide passages 1d and 1e are joined to the outer peripheral portion of the large combustion chamber, and the guide passages 1d and 1e are joined in opposite directions so as not to interfere with each other.

Further, the vertical cross section has a wedge-shaped shape in which the bottom surface of the large combustion chamber 1a is flat and the side surfaces are inclined inward. The small combustion chambers 1b and 1c are spherical combustion chambers to facilitate the outflow of flame.

On the other hand, the fuel injection valves 3a, 3 mounted on the cylinder head 2
The b is arranged above the small combustion chambers 1b and 1c.

Now, the fuel injected from the fuel injection valves 3a and 3b collides with the wall surface in the small combustion chambers 1b and 1c, ignites, and the flame spreads along the wall surface. The small combustion chambers 1b and 1c have a short distance to the wall surface, a small volume, and are in a rich air-fuel mixture state, so that rapid combustion does not occur and the combustion is relatively gentle.

In the spray flame that ignited next, since the piston top clearance lc was extremely small at this time, the flame outflow toward the upper part of the piston was small, and most of the And flows into the large combustion chamber 1a.
In this inflow direction, since the guide passages 1d and 1e are connected to the outer peripheral direction of the large combustion chamber 1a, the inflow direction flows toward the outer periphery and the large combustion chamber 1a.
It makes a turning motion within 1a. Further, the swirling motion is further strengthened by arranging the air swirl flow SW provided in the large combustion chamber 1a in the same direction as the swirling motion direction.

The spray flame when flowing into the large combustion chamber 1a flows in a semi-combustion state due to lack of air, but after the inflow it is possible to secure a sufficient amount of air, so combustion is promoted, and further swirling motion is given Up to this point, air can be obtained sufficiently and combustion can be improved.

By the above, while suppressing the initial combustion moderately, medium,
It is possible to activate late combustion more actively than before, suppress the generation of nitrogen oxides, prevent the generation of black smoke, and improve fuel efficiency.

[Effect of device]

The present invention relates to a combustion chamber of a diesel engine having a combustion chamber at the top of the piston, and a large combustion chamber recessed at the center of the piston top and a plurality of small combustion chambers symmetrically arranged around the large combustion chamber. Chamber, a plurality of guide passages communicating between the large combustion chamber and the small combustion chamber and opening in the circumferential direction of the large combustion chamber in a direction coinciding with the swirl flow in the large combustion chamber, and the center of each small combustion chamber. And a fuel injection valve for injecting fuel toward each small combustion chamber, the swirl of the large combustion chamber arranged in the center of the cylinder is Is enhanced by the spray motion ejected from a plurality of small combustion chambers symmetrically arranged around the fuel cell, promotes diffusion with air in the large combustion chamber to improve combustion, and further fuels to a plurality of small combustion chambers. For injection, change the timing, amount, etc. freely. Timing for jetting to large combustion chamber because it, by an amount or the like is controlled to some extent, an effect such that the combustion in a large combustion chamber it is possible to better control.

[Brief description of drawings]

FIG. 1 is a plan view of a combustion chamber according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II of the same, FIG. 3 is a plan view showing a conventional combustion chamber, and FIG. It is a IV-IV sectional view. 1 ... Piston, 1a ... Large combustion chamber 1b, 1c ... Small combustion chamber, 1d, 1e ... Guide passage 2 ... Cylinder head, 3a, 3b ... Fuel injection valve

Claims (1)

(57) [Scope of utility model registration request] 1. A combustion chamber of a diesel engine having a combustion chamber at the top of a piston, wherein a large combustion chamber is provided at the center of the piston top and a plurality of small chambers symmetrically arranged around the large combustion chamber. A combustion chamber, a plurality of guide passages communicating with the small combustion chamber and the large combustion chamber and opening in the circumferential direction of the large combustion chamber in a direction coinciding with the swirl flow in the large combustion chamber, and of the small combustion chambers. A combustion chamber for a diesel engine, comprising: a fuel injection valve that is mounted on a cylinder head above a central portion and injects fuel toward each small combustion chamber.