JPH0720340Y2 - Direct injection combustion chamber of diesel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a direct injection combustion chamber of a diesel engine.

(Prior Art) Conventionally, the type of combustion chamber of a diesel engine is roughly divided into two types, that is, a single chamber type and a sub chamber type. This combustion chamber single chamber type supplies fuel to a single combustion chamber. It is called a direct injection type because it is directly injected and burned. This direct injection type combustion chamber is shown in FIGS. 3 and 4, and as shown in FIG. 3, the direct injection type combustion chamber 1 is formed by notching in a concave shape at the top of the piston 2. The side wall surface 1a of the direct injection type combustion chamber 1 is perpendicular to the axial center 2a of the piston 2 and, when cut along a plane including the combustion chamber 1, the outline of the side wall surface 1a is a circle. It is shaped like an eggplant. A multi-injection fuel injection nozzle 3 whose axis coincides with the axis 2a of the piston 2 is arranged above the combustion chamber 1, and each of the nozzles 3a, 3b, 3c, 3d (first In Figure 4, 3a and 3b
(Only shown), the fuel is injected toward the side wall surface 1a in the combustion chamber 1. Here, the number of nozzles of the nozzle 3 shown in FIGS. 3 and 4 is four, and the nozzles 3a, 3b, 3c, 3d are arranged counterclockwise in that order.

Next, the flow of each fuel injected from the respective nozzle holes 3a, 3b, 3c, 3d of the nozzle 3 toward the side wall surface 1a in the combustion chamber 1 will be described with reference to FIG. As shown in the figure, the respective fuels injected from the respective nozzles 3a, 3b, 3c, 3d toward the side wall surface 1a collide head-on with the site X of the side wall surface 1a of the combustion chamber 1 and bifurcate. Each of the sprays divided into two branches comes to flow along the side wall surface 1a. Then, the spray that has flowed along the side wall surface 1a is sprayed from the adjacent side and separated from one of the spray and the side wall surface.
Frontal collisions occur at the portions Y of 1a, and the sprays that have caused the collisions then flow toward the axial center 2a of the combustion chamber 1, respectively.

(Problems to be Solved by the Invention) As described above, each fuel injected from each of the injection ports 3a, 3b, 3c, 3d toward the side wall surface 1a is first in the portion X of the side wall surface 1a of the combustion chamber 1. Since a head-on collision and then a head-on collision at one portion Y of the side wall surface 1a with one of the sprays injected from the adjacent side and separated, the momentum of the spray is greatly reduced. Therefore, almost no spray momentum remains in the fuel spray after head-on collision at the part Y, and in reality, the spray colliding at the part Y hardly flows toward the axial center 2a of the combustion chamber 1. . Then, since the air-fuel mixture due to the spray is hardly formed in the portion Z where the fuel spray does not pass, smoke and NO, CO, HC and other exhaust gas emission factors greatly increase. However, there is a problem that fuel efficiency is deteriorated.

The purpose of the present invention is to reduce the damping of the spray momentum to promote the formation of an air-fuel mixture, reduce the emission factors such as smoke and NO, CO, HC, etc., and improve the fuel efficiency of a diesel engine. It is to provide a direct injection type combustion chamber.

(Means for Solving the Problem) In order to achieve the above object, the direct injection type combustion chamber of the diesel engine of the present invention has a side wall surface of the combustion chamber, which has a semicircle of twice the number of nozzle nozzles. Notches are formed in the axial direction of the piston so as to be continuous on the circumference, and are formed in the outer shape of the petals of the sunflower, and the intersection of the outer shape of each of the substantially semicircular cutout portions and the outer shape of the adjacent cutout portion. Are configured so as to face each other in the spray direction of the nozzle.

(Operation) According to the present invention, the fuel spray injected from each nozzle nozzle is directed toward the intersection of the outer contour of the substantially semi-circular cutout portion and the outer contour of the adjacent cutout portion, and the point of intersection is sharp. In, the spray momentum is bifurcated so that the momentum of the spray is hardly attenuated, and the spray flows along the outline of the cutout having a substantially semicircular cross section.
And, the tip of the spray that has flowed along the outline of the cutout having a substantially semicircular cross section is, at the next intersection, one of the sprays injected from the next injection port and separated at the next two intersections,
The sprays contact and abut at an acute angle so that the momentum of the spray is hardly attenuated, and the abutted sprays together forcefully flow toward the axial center of the combustion chamber.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a top view of a direct injection type fuel chamber of a diesel engine showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA in FIG. 1, which is the same as the above-mentioned prior art. Functions and functions have the same reference numerals, and the description thereof will be omitted to avoid duplication. As shown in FIG. 1 and FIG. 2, the direct injection type combustion chamber 11 of the diesel engine of the present embodiment is different from that of the prior art in that the side wall surface of the combustion chamber 11 is a semicircle. It is cut out in the axial direction 2a of the piston 2 so as to be connected to the upper side and is formed in the outer shape of the petals of the sunflower. And the intersection 16 with the outer contour 15 of the adjacent notch portion are configured so as to coincide with and face the spray direction of the nozzle 3. Here, the number of cutouts having a substantially semicircular cross section, that is, the number of sunflower petals is twice the number of nozzles of the nozzle 3. That is, in the present embodiment, since the number of injection holes is four, the number of cutouts is twice that, which is eight. Further, the outer contour of the cutout portion of the combustion chamber 11 and the outer contour of the adjacent notch portion.
The angle θ between the tangent 12 to the outer shell 14 and the tangent 13 to the outer shell 15 at the adjacent notch at the intersection 16 with 15 is an acute angle (θ = 0.
℃ is included). Further, the reference numerals 14 and 15 of the outer contour of the cutout portion and the outer contour of the adjacent cutout portion of the combustion chamber 11 are different for easy understanding, but the shape of each notch portion is exactly the same. The shapes of the notches of the combustion chamber 11 are all the same.

With this configuration, the fuel spray injected from the injection port 3a of the nozzle 3, as shown in FIG. 1, has a substantially semi-circular cutout portion outer contour 14 and an adjacent notch portion outer contour. To the respective intersections 16 with 15, the bifurcated so that the momentum of the spray is hardly attenuated at the sharp intersections 16, so as to flow in the direction of the arrow along the notch outlines 14 and 15 each having a substantially semicircular cross section. become. Then, at the intersection 16 next to the tip of each spray flowing along the outlines 14 and 15 of the cutout having a substantially semicircular cross section, at the intersection 16 next to the spray nozzle 3b, 3d, at the intersection 16 next to the two spray nozzles. One of the separated sprays comes into contact with and comes into contact with each other at an acute angle so that the momentum of the spray is hardly attenuated, and the abutting sprays together are directed toward the axis 2a of the combustion chamber 11 as shown by arrows. It begins to flow vigorously. Similarly, the fuel sprays injected from the other injection ports 3b, 3c, 3d also flow vigorously toward the axial center 2a of the combustion chamber 11 without their momentum being attenuated.

As described above, according to the present embodiment, the injection ports 3a, 3 of the nozzle 3 are
The fuel spray injected from b, 3c, 3d is prevented from head-on collision with the side wall surface of the combustion chamber 11 and the spray tip separated and injected from the adjacent injection port. Attenuation is reduced, the formation of air-fuel mixture by spraying is promoted, and exhaust gas emission factors such as smoke, NO, CO, and HC are reduced, and fuel consumption is improved.

The present invention is not limited to the above embodiment,
Various modifications can be made without departing from the spirit of the invention. For example, in the above-described embodiment, the number of nozzles of the nozzle 3 is four.
However, the number is not limited to four, and any number may be used as long as it is two or more. If the number of the nozzles is n (n is an integer of 2 or more), it is approximately a semicircle. Since the number of notches forming the cross section is twice the number of nozzles,
It goes without saying that the number of the cutouts is 2n.

(Effect of the Invention) As described above, according to the present invention, the side wall surface of the direct injection type combustion chamber of the diesel engine is arranged so that the semicircle of twice the number of the nozzle orifices is continuous on the circumference. Notched in the axial direction and formed in the outer shape of the petals of the sunflower, and the intersections of the outer contours of the respective substantially semicircular cutout portions and the outer contours of the adjacent cutout portions match and face the spray direction of the nozzle. Therefore, it is possible to prevent the fuel spray injected from each injection port from colliding head-on with the side wall surface of the combustion chamber and the spray tip separated from the injection port adjacent to the injection port. The decrease in the momentum possessed is reduced, the formation of the air-fuel mixture by spraying is promoted, the emission factors of smoke and NO, CO, HC, etc. are reduced, and the fuel consumption is improved.

[Brief description of drawings]

FIG. 1 is a top view of a direct injection type combustion chamber of a diesel engine showing an embodiment of the present invention, and FIG. 2 is AA in FIG.
A sectional view, FIG. 3 is a top view of a direct injection type combustion chamber of a diesel engine showing a conventional technique, and FIG. 4 is BB in FIG.
FIG. 1,11 …… Direct injection combustion chamber of diesel engine, 1a, 1
4,15 ... Side wall of combustion chamber, 2 ... Piston, 2a ... Piston axis (fuel injection nozzle axis), 3 ... Multiple nozzle fuel injection nozzle, 3a, 3b ... Nozzle, 16 ... The intersection of the outline of the cutout and the outline of the adjacent cutout.

Claims (1)

[Scope of utility model registration request] 1. A multi-injection fuel injection nozzle, which is arranged above a piston and whose axis coincides with the axis of the piston, is directly sprayed with fuel from the nozzle and is formed in a concave shape at the top of the piston. In a combustion chamber of a diesel engine in which the outline of the side wall of the recess is a circle when cut by a plane perpendicular to the axial center of the piston, the side wall surface of the combustion chamber is twice as many as the injection port of the nozzle. Is formed by cutting out in the axial direction of the piston so that substantially semicircles of the semicircle are continuous on the circumference, and is formed in the outer shape of the petals of the sunflower. A direct injection combustion chamber for a diesel engine, characterized in that the intersection with the outer contour of the portion is configured to face and coincide with the spray direction of the nozzle.