JPH05202755A - Diesel engine - Google Patents

Abstract

PURPOSE:To reduce the production quantity and exhaust quantity of black smoke by radially arranging the groove-like auxiliary combustion chamber, which is connected to the upper section of the combustion chamber formed on the top of a piston, so as to be positioned between the injection holes of a fuel injection nozzle installed on a cylinder head. CONSTITUTION:A piston 3, whose top is opened and in which a recessed combustion chamber is formed, is liftably fitted in a cylinder block 1. A fuel injection nozzle 8, to which a plurality of injection holes formed in a specified spaced relation in the peripheral direction, is arranged to the cylinder head 5 installed on the upper section of the cylinder block 1 so as to be positioned directly above the combustion chamber 9 in the piston 3. In addition, a groove-like auxiliary combustion chamber 10, whose top is opened and which is connected to the upper section of the combustion chamber 9, is radially arranged so as to be positioned between the injection holes 11 of the fuel injection nozzle 8 in a plane. By this constitution, air and fuel spray are properly mixed, and combustion temperature is increased, reducing the production quantity and exhaust quantity of black smoke are reduced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a diesel engine.

[0002]

2. Description of the Related Art An example of a piston portion of a diesel engine is shown in FIGS.

In FIGS. 6 and 7, 1 is a cylinder block,
Reference numeral 2 is a hollow cylinder liner fitted in the cylinder block 1, 3 is a piston fitted in the cylinder liner 2 so as to be able to move up and down, 4 is fitted on the outer circumference of the piston 3, and when the piston 3 is raised and lowered, A piston ring 5 which is slidable with respect to 2 is a cylinder head mounted on the upper surface of the cylinder block 1, 6 is an intake port formed in the cylinder head 5, and 7 is an intake port 6
A liftable intake valve for opening and closing the outlet of the fuel injection nozzle 8 is a fuel injection nozzle attached to the cylinder head 5.

The piston 3 is provided with a combustion chamber 9 whose upper surface is open and which is recessed. Thus, in the combustion chamber 9 shown in FIG. 6, the wall surface 9a is vertical and the bottom surface 9b is
Is flat, and the inner circumference 9c of the upper inlet is narrowed so that the inner diameter is slightly smaller than the wall surface 9a, and is formed as a wide-mouthed bottle as a whole. Further, the combustion chamber 9 shown in FIG.
When viewed in cross section, the wall surface 9a and the bottom surface 9b have a curved shape with a required curvature, and the protrusion 9 is formed at the center of the bottom surface 9b.
d is provided to form a heart shape.

In the diesel engine of FIGS. 6 and 7 described above, in the intake stroke, the intake valve 7 is opened, air is swirled from the intake port 6 and enters the cylinder liner 2, and from the cylinder liner 2 to the combustion chamber 9. In the compression process, the fuel is injected from the fuel injection nozzle 8 into the combustion chamber 9 near the top dead center of the piston 3, and the air and the fuel spray are mixed and burned.

[0006]

However, in any of the above-mentioned engines, there is a limit to the reduction of the amount of black smoke emitted, and it is difficult to respond when exhaust gas regulations become stricter than the current situation. was there.

In view of the above-mentioned circumstances, the present invention has an object to reduce the amount of black smoke emitted so as to be able to comply with strict exhaust gas regulations.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a cylinder head is provided with a piston having a combustion chamber having an open upper surface and a recessed shape, which is vertically movable in a cylinder block and is attached to the upper portion of the cylinder block. A fuel injection nozzle in which a plurality of injection holes are formed at required intervals in the circumferential direction is arranged so as to be located immediately above the combustion chamber of the piston, and the upper surface of the piston has an upper surface opened. A groove-shaped auxiliary combustion chamber connected to the upper portion of the combustion chamber is radially provided so as to be located between the injection holes of the fuel injection nozzle in plan view.

[0009]

In the suction process, the air taken in from the outside is swirled to be introduced into the combustion chamber and is also introduced into the combustion chamber as a vertical flow through the auxiliary combustion chamber. Therefore, both airs collide with each other in the combustion chamber, and the air flow in the combustion chamber is promoted.

The fuel is injected from the fuel injection nozzle when the piston is in the vicinity of the top dead center. However, since the air flow in the combustion chamber is promoted, the mixture of the air and the fuel is well mixed. As a result, the combustion temperature rises, and as a result, the amount of black smoke generated and the amount of emission thereof decrease.

In the explosion process, the flame in the cylinder liner is rapidly propagated to the combustion chamber through the auxiliary combustion chamber, so that the air in the combustion chamber can be effectively used, and as a result, the amount of black smoke generated can be increased. Emissions are reduced.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 to 5 show an embodiment of the diesel engine of the present invention.

The basic construction of the diesel engine of this embodiment is the same as that shown in FIG. Thus, on the upper surface of the piston 3, the auxiliary combustion chamber 10 in the shape of a semi-circular arc is arranged radially with respect to the outer periphery of the combustion chamber 9 when viewed in plan and is formed in a downward slope toward the combustion chamber 9. Is provided, and the end of the auxiliary combustion chamber 10 on the combustion chamber 9 side is connected to the upper inlet of the combustion chamber 9. Further, as shown in FIG. 4, the auxiliary combustion chamber 10 is located between the adjacent injection holes 11 provided in the fuel injection nozzle 8 in a plan view, and the circumference of the combustion chamber 9 of the auxiliary combustion chamber 10 is located. The width W in the direction is such that the spray 12 injected from the injection hole 11 does not enter, for example, W = (0.
1 to 0.3) × D (where D is the cylinder bore diameter), and the maximum depth of the auxiliary combustion chamber 10 is the inner circumference 9c of the upper inlet portion.
Is formed to have a thickness of approximately 1/2 (≈H / 2).

In the figure, 13 is a flame.

In the diesel engine described above, in the intake stroke, the intake valve 7 is opened as shown in FIG. 1, air is swirled from the intake port 6 to enter the cylinder liner 2, and the air is burned through the cylinder liner 2. It is introduced into the chamber 9 and, at the same time, is introduced into the combustion chamber 9 through the auxiliary combustion chamber 10 as a vertical flow as shown by the arrow A in FIG. For this reason, in the combustion chamber 9, the air introduced by being swirled and the air introduced through the auxiliary combustion chamber 10 are mixed with each other, and the air flow is promoted.

Further, in the compression process, as shown in FIG. 3, the fuel is injected from the fuel injection nozzle 8 in the vicinity of the top dead center of the piston 3 obliquely downward toward the inner periphery 9c of the upper inlet portion of the combustion chamber 9 and the wall surface 9a. Radially injected, spraying air and fuel 12
Are mixed and burned. In this case, in the combustion chamber 9,
Since the air flow is promoted as described above, the air and the spray 12 are mixed well, and as a result, the combustion temperature rises, the amount of black smoke generated decreases, and the amount of discharge thereof also decreases.

Further, in the explosion process, since the piston 3 starts descending, the fuel injected with a delay in the cylinder liner 2 is burned, but the flame 13 rapidly propagates from the auxiliary combustion chamber 10 to the combustion chamber 9. (See FIG. 5). Therefore, the air in the combustion chamber 9 can be effectively used, the amount of black smoke generated is reduced, and the amount of discharge thereof is also reduced. In particular, in the timing retard when the fuel injection is started at the time when the piston 3 starts to descend from the top dead center, in order to effectively use the air in the combustion chamber 9,
It is always necessary to provide the auxiliary combustion chamber 10.

In the embodiment of the present invention, the case where the auxiliary combustion chamber is provided in the piston of the diesel engine shown in FIG. 6 has been described, but the auxiliary combustion chamber may be provided in the piston of the diesel engine shown in FIG. Needless to say, various changes can be made without departing from the scope of the present invention.

[0020]

According to the diesel engine of the present invention,
It is possible to achieve the excellent effect of being able to reduce the amount of black smoke emitted and to comply with stricter exhaust gas regulations than at present.

[Brief description of drawings]

FIG. 1 is a front view of an inhalation process showing a part of the diesel engine of the present invention in a longitudinal section.

FIG. 2 is a view taken along the line II-II in FIG.

FIG. 3 is a front view of a compression process showing a part of the diesel engine according to an embodiment of the present invention in a longitudinal section.

FIG. 4 is an enlarged plan view of a piston viewed from the vicinity of a lower end portion of the fuel injection nozzle shown in FIG.

FIG. 5 is a front view of an explosion process shown in a longitudinal section of a part of an embodiment of the diesel engine of the present invention.

FIG. 6 is a front view of an inhalation process showing a part of the conventional diesel engine in a longitudinal section.

FIG. 7 is a front view of another example of the conventional diesel engine, showing a suction process in which a part is longitudinally cut.

[Explanation of symbols]

 1 Cylinder Block 3 Piston 5 Cylinder Head 8 Fuel Injection Nozzle 9 Combustion Chamber 10 Auxiliary Combustion Chamber 11 Injection Hole

Claims (1)

[Claims] 1. A piston having a combustion chamber having an open upper surface and a recessed shape is fitted in a cylinder block so as to be able to move up and down, and a cylinder head mounted on an upper portion of the cylinder block is provided with a required amount in a circumferential direction. A fuel injection nozzle having a plurality of injection holes formed at intervals is arranged so as to be located immediately above the combustion chamber of the piston, and a groove having an upper surface opened to the upper surface of the piston and connected to the upper portion of the combustion chamber. A diesel engine, characterized in that the auxiliary combustion chambers in the shape of a circle are radially provided so as to be located between the injection holes of the fuel injection nozzles in plan view.