JPS6014888Y2 - Diesel engine swirl chamber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a swirl chamber of a diesel engine, and in particular to a glow plug arrangement structure.

Conventionally, in a diesel engine with a swirl chamber, the cooling loss in the swirl chamber was large and the startability at low temperatures was poor.

For this reason, glow plugs were used in addition to controlling vortices and fuel spray, but improvements could not be easily achieved.

FIG. 1 shows the vortex chamber structure of a conventional diesel engine, in which a vortex chamber f is formed by a recess C provided in a mouthpiece member having a communication hole a and a substantially hemispherical recess e in a cylinder head d. A fuel injection nozzle g opens into this swirl chamber f, and a glow plug h projects therefrom.

The center lines of the injection nozzle g1, the glow plug h, and the communication hole a are all arranged on the same plane that includes the center line of the swirl chamber f.

In this structure, compressed air from the main combustion chamber (not shown) flows into the vortex chamber f through the communication hole a, and then becomes a vortex as shown by the arrow.

Then, this vortex collides with the glow plug h and mixes with the high-pressure fuel injection injected from the injection nozzle g.

In this case, the vortex is heated to some extent by the glow plug h, but on the other hand, the glow plug h is cooled by the strong vortex, and even if the fuel spray collides with or comes into contact with the glow plug h, it cannot be ignited, and the vortex Immediately after flowing in, the fuel collides with the glow plug h and separates or weakens the flow, making it difficult to form a good air-fuel mixture with the high-pressure fuel spray, resulting in poor starting.

For this reason, while completely retracting the plug h from the swirl chamber f or making the protrusion into the swirl chamber f extremely short,
A system has been proposed that reflects the fuel spray and hits the plug (for example, see Japanese Utility Model Application Publication No. 53-81704), but in the case of spraying, the preheating effect of the plug h may be reduced or the fuel may not be reflected properly. It was difficult to match the fuel injection, and the startability was poor, so it was not possible to find a satisfactory solution.

The present invention provides a structure that can eliminate the above-mentioned drawbacks, and an embodiment of the present invention is shown in FIGS. 2 and 3 below.

Figure 2 is a vertical sectional view showing the main parts of the present invention, and Figure 3 is a vertical cross-sectional view showing the main parts of the present invention.
FIG. 3 is a vertical cross-sectional view taken along the line ■-■ in the figure.

In FIGS. 2 and 3, 1 is a cylinder head, and 2 is a substantially hemispherical recess formed in the cylinder head 1 facing downward.

Reference numeral 3 denotes a base member inserted and fixed from below the cylinder head 1. The base member 3 has a truncated conical recess 4 opposite to the hemispherical recess 2 on the upper side, and a communication hole 5 on the lower side.

The hemispherical recess 2 and the truncated conical recess 4 constitute a swirl chamber 6.

Reference numeral 7 denotes a fuel injection nozzle that opens into the swirl chamber 6 so that the fuel spray directly impinges on the glow plug 8. The glow plug 8 has a tip portion 8a that protrudes into the swirl chamber 6 so as to come into contact with half of the mainstream of the swirl. have

Reference numeral 9 denotes a piston that reciprocates vertically on the cylinder wall 10a of the cylinder block 10. A suitable recess is provided at the upper end of the piston 9, and the lower end surface of the cylinder head is connected to the main combustion chamber 1.
1 is the structure.

The swirl chamber 6 and the main combustion chamber 11 communicate with each other through a communication hole 5.

Here, the attachment state of the communication hole 5, the injection nozzle 7, and the glow plug 8 will be described in detail.

The cross section shown in FIG. 2 is included in a plane that includes a center line that is perpendicular to the central axis of travel of the vortex and that bisects the width direction of the communication hole 5 in the same direction as the central axis of travel of the vortex. swirl chamber 6
The communication hole 5, injection nozzle 7, and glow plug 8 are all inclined with respect to the center line 6a of It will be done.

On the other hand, in the cross section of FIG. 3, the communication hole 5 and the injection nozzle 7 are not inclined with respect to the center line 6a, and only the glow plug 8 is inclined at an inclination angle θ of about 50 degrees and protrudes into the swirl chamber 6.
The leading edge 8b of the tip portion 8a is located in contact with or slightly apart from the center line 6a.

Incidentally, the inclination angle θ of the glow plug 8 may be in the range of 40 to 60 degrees.

In FIG. 3, the width direction of the communication hole 5 is determined, and the width direction of the communication hole 5 is determined, and each side of the communication hole 5 has the same dimension on both sides of the center line 6a.

If the extension lines of both ends 5a and 5b of the width of the communication hole 5 to the swirl chamber 6 are respectively la and lb, then the area surrounded by the line 1a and the center line 6a is also surrounded by the line 1b and the center line 6a. A region R is assumed, and the tip portion 8a of the glow plug 8 is located in this region.

In other words, all the parts of the glow plug 8 that protrude into the swirl chamber 6 are located only to the left of the center line 6a of the swirl chamber 6 in FIG.

Next, the functions and effects of the above configuration will be explained.

During the compression stroke of the piston 9, compressed air flows from the main combustion chamber 11 through the communication hole 5 into the swirl chamber 6, whose width is shown in FIG.
As shown in , a vortex flow having a main stream with a high flow rate regulated by the width of the communication hole 5 flows in a counterclockwise direction as shown by an arrow Y.

The main stream of this vortex travels around more than half of the vortex chamber 6 and collides with the glow plug 8 or the fuel spray from the injection nozzle 7.

In this case, since the tip portion 8a of the glow plug 8 contacts only half of the mainstream of the vortex at most, it is maintained at a high temperature without being unnecessarily cooled, and furthermore,
The high-pressure fuel spray directly collides with the tip portion 8a of the glow plug 8, which is maintained at a high temperature, and the fuel becomes easily ignited.

On the other hand, since the remaining half of the main flow does not collide with the glow plug 8, a high flow velocity is maintained and the remaining half is sufficiently mixed with the high-pressure fuel spray.

Therefore, since fuel is ignited by the hot plug and a good air-fuel mixture existing near the ignited part is reliably combusted, starting can be achieved reliably even at low temperatures.

As described above, the present invention provides a diesel engine with a swirl chamber, in which a center line that is perpendicular to the central axis of travel of the whirlpool and that divides the width direction of the communicating hole into thirds in the same direction as the central axis of travel of the whirlpool. The glow plug is inclined with respect to a plane containing the plane, and extends from the side of the vortex chamber to the vicinity of the plane, and has its tip end in the spray direction of the fuel injection nozzle, and one side of the vortex chamber that is parted by the plane. Since the fuel injection nozzle is located only on the side, and the fuel injection nozzle is arranged so that the center line of the fuel spray and the above-mentioned plane coincide, an appropriate combination of the glow plug and the vortex can be obtained, which improves starting performance. It can bring about great effects.

[Brief explanation of drawings]

Figure 1 shows the swirl chamber of a conventional diesel engine.
FIG. 2 is a longitudinal cross-sectional view showing a main part of an embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along the line ■--■ in FIG. 5... Communication hole, 6... Vortex chamber, 6a.
... Center line of swirl chamber, 7 ... Fuel injection nozzle, 8 ... Glow plug, 8a ...
Tip of glow plug, 11... Main combustion chamber.

Claims (1)

[Scope of utility model registration request] A swirl chamber of a diesel engine, which is provided with a fuel injection nozzle and a glow plug and communicates with a main combustion chamber through a communication hole, the communication hole extending linearly from the main combustion chamber toward the swirl chamber,
In addition, the diesel engine has a structure that opens approximately tangentially to the swirl chamber to generate a swirl in the incoming intake air, and a communication hole opens at the center in the width direction of the swirl chamber in the same direction as the nodal central axis of the swirl. In the vortex chamber of the engine, the glow plug is inclined to a plane that includes a center line that bisects the width direction of the communication hole in the same direction as the nodal central axis of the vortex, and extends from the side of the vortex chamber to the vicinity of the plane. The fuel injection nozzle is located only on one side of the vortex chamber which extends in the spray direction of the fuel injection nozzle and is constructed on the plane, and the fuel injection nozzle is arranged so that the center line of the fuel spray and the plane are aligned. Swirl chambers of a diesel engine characterized in that they are arranged to match.