JPS6210432Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to improving the combustion chamber of a swirl chamber type diesel engine. Specifically, in addition to the main injection hole that connects the swirl chamber and the main chamber, a sub-nozzle hole is provided to improve combustion. Regarding improvements to combustion chambers.

The swirl chamber type is known as a combustion chamber suitable for high-speed diesel engines, but in order to further improve its combustion properties, the ones shown in Figures 1 and 2 have been proposed (for example, 1971-
No. 105509).

To explain this, the swirl chamber 1 is formed in a substantially spherical shape between a cylinder head 2 and a mouthpiece 3 fitted from the bottom surface thereof, and is connected to the main chamber 6 via a main nozzle 4 and a sub-nozzle 5 having a relatively small diameter. It's communicating.

The main nozzle 4 is formed tangentially to the swirl chamber 1,
The gas jet from the swirl chamber 1 during combustion is ejected toward the center of the main chamber 6. On the other hand, the small-diameter sub-nozzle 5 is formed to substantially coincide with the injection center axis of the fuel injection valve 7 facing the swirl chamber 1, so that a part of the injected fuel flows out into the main chamber 6 during the ignition delay. It is designed to let you do so.

According to such a combustion chamber, not only the vortex chamber 1 but also the main chamber 6 in which gas flows gently through the sub-nozzle 5
Since fuel is supplied to both chambers and combustion proceeds in both chambers, the air utilization rate increases compared to the case where the entire amount of injected fuel is supplied only to the swirl chamber 1 for combustion, which has the advantage of improving combustion properties. be.

By the way, in such a combustion chamber, just before the end of the compression stroke, the jet of high-temperature gas combusted in the swirl chamber 1 passes through the main nozzle 4, as described above.
Since unburned fuel vapor or unevaporated fuel liquid with relatively low temperature flows through the sub-nozzle 5, a significant temperature difference occurs between the main nozzle 4 and the sub-nozzle 5, and thermal stress is concentrated in this part. There is a problem that cracks (see Fig. 2) and damage occur due to this.

This idea was devised by focusing on these conventional problems, and in a swirl chamber type diesel engine that has a main nozzle hole and a sub nozzle hole, the inner wall surfaces of the two nozzle holes that are closest to each other The purpose of the present invention is to solve the above-mentioned problem by forming the curvature of the curvature of the curvature of the curvature of the curvature of the wafer.

This invention will be explained below based on the drawings.

3, 4 and 5 show an embodiment of this invention. First, the configuration will be explained.

In FIG. 3, the cylinder head 11 is fixed on the cylinder block 12, closes the cylinder hole 13, and defines a main combustion chamber 15 between the cylinder hole 13 and the piston 14. are doing. A base member 16 is fitted into and fixed to the cylinder head 11, and a substantially spherical swirl chamber 17 is formed between the base member 16 and the cylinder head 11. Further, 18 is a fuel injection nozzle attached to the cylinder head 11, and the tip of this fuel injection nozzle 18 is connected to the swirl chamber 1.
It is arranged so that it faces 7. A main nozzle hole 19 is formed in the mouthpiece member 16 and extends in the tangential direction of the inner wall of the swirl chamber 17.The upper end of this main nozzle hole 19 is connected to the swirl chamber 17, and the lower end is connected to the main combustion chamber 15 (particularly the main nozzle hole 19). (towards the center), each opening is open. Further, 20 is a sub-nozzle hole formed in the mouthpiece member 16, and this sub-nozzle hole 20 is formed on an extension of the axis of the fuel injection nozzle 18, and its upper end is connected to the swirl chamber 1.
7, its lower end is connected to the main combustion chamber 15 of the main injection hole 19.
Each side has an opening. Further, the sub-nozzle hole 20 has a substantially circular cross section as shown in FIG.
The cross-sectional area of the passage is smaller than that of the main nozzle hole 19. Here, as shown in FIGS. 4 and 5, the main nozzle hole 19 has a substantially heart-shaped cross section. That is, the inner wall surface 19a of the main nozzle hole 19 on the side of the sub nozzle hole 20 (the side close to the sub nozzle hole 20) is connected to the main nozzle hole 19 of the sub nozzle hole 20.
The inner wall surface 20a of the main nozzle hole 19 and the inner wall surface 20a of the sub nozzle hole 20 are curved with the same curvature as the inner wall surface 20a of the side, and as a result, as shown in detail in FIG.
The distance l between the inner wall surfaces 19a and 20a is the same at all positions in the circumferential direction.
In addition, at the opening of the main nozzle hole 19 on the swirl chamber 17 side,
As shown in FIG. 3, the shoulder portion 19b of the inner wall surface 19a is rounded with a predetermined curvature in the longitudinal section of the mouthpiece member 16 (the section taken in a plane including the respective axes of the main and auxiliary nozzle holes 19, 20). is formed, and furthermore,
The merging portion 21 between the main nozzle hole 19 and the sub nozzle hole 20 is similarly rounded with a predetermined curvature.

Next, the effect will be explained.

When the swirl chamber type diesel engine starts, first, the piston 14 descends to draw outside air into the main combustion chamber 15. Next, when the piston 14 rises,
The air in the main combustion chamber 15 is compressed, and a portion of this compressed air flows into the swirl chamber 17 mainly through the main nozzle hole 19 and generates a swirl. At this time, when fuel is injected from the fuel injection nozzle 18 into the swirl chamber 17, a portion of the fuel is transferred to the sub-nozzle hole 2 during the ignition delay period.
The fuel flows into the main combustion chamber 15 through the main combustion chamber 15 and is ignited within the chamber 15, and the remaining fuel (most of the fuel) is ignited and combusted within the swirl chamber 17. The combustion gas (high temperature gas) in this swirl chamber 17 then flows back from the swirl chamber 17 into the main combustion chamber 15 through the main nozzle hole 19, mixes with compressed air in the main combustion chamber 15, and burns. In this way, high-temperature combustion gas passes through the main nozzle hole 19, whereas low-temperature unburned fuel or fuel vapor passes through the auxiliary nozzle hole 20. As a result, a temperature gradient occurs in the partition wall separating the nozzle holes 19 and 20. However, in this embodiment, the inner wall surfaces 19 of the main nozzle holes 19 that are adjacent to each other
Since the distance between a and the inner wall surface 20a of the sub-nozzle hole 20 is all the same in the circumferential direction, thermal stress does not concentrate on a part of the partition wall, and cracks occur in this part. This can be prevented. That is, the strength of the partition wall portion against thermal stress is improved. Further, as described above, since the shoulder portion 19b of the inner wall surface 19a and the merging portion 21 are rounded, it is possible to prevent cracks from occurring due to concentration of thermal stress. Note that since the passage cross-sectional area of the main nozzle hole 19 is the same as that of the conventional one, the throttling loss does not increase and the performance of the swirl chamber diesel engine as a whole does not deteriorate.

FIG. 6 shows another embodiment of this invention.
In this embodiment, the inner wall surface 19a of the main nozzle hole 19 is
It is curved to have a predetermined curvature centering on the opening of the sub-nozzle hole 20 on the swirl chamber 17 side in the longitudinal section. Therefore, the main nozzle hole 19
The inner wall surface 19a forms a part of a spherical surface (or a similar curved surface) as a whole. The other structures and functions are the same as those of the embodiment described above, and this embodiment can further improve the thermal and mechanical strength.

As explained above, according to this idea,
A main combustion chamber defined in a cylinder, a swirl chamber into which fuel is injected by a fuel injection nozzle, a main injection hole communicating these two chambers, and a main injection hole extending in the axial direction of the fuel injection nozzle. In a swirl chamber type diesel engine, the swirl chamber is provided with a sub nozzle hole that communicates the swirl chamber with an end of the main nozzle hole on the main combustion chamber side, and an inner wall surface of the main nozzle hole on the side of the sub nozzle hole is connected to the inner wall surface of the main nozzle hole on the side of the sub nozzle hole. Since it is curved so that it is equidistant from the inner wall surface on the main nozzle hole side, the strength (durability) of the member between the two nozzle holes is improved, and the occurrence of cracks can be suppressed. , deterioration of engine performance due to throttling loss of the main injection hole can also be prevented.

Furthermore, the embodiment shown in FIG. 6 can further improve the above effects.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing a conventional swirl chamber type diesel engine, Fig. 2 is a sectional view taken along the - arrow in Fig. 1, and Fig. 3 is an embodiment of the swirl chamber type diesel engine according to this invention. 4 is a diagram showing the shape of the main nozzle hole shown in FIG. 3, FIG. 5 is a sectional view taken along the - arrow in FIG. 3, and FIG. 6 is another embodiment of this invention. FIG. 2 is a vertical cross-sectional view showing the swirl chamber portion thereof. 13... Cylinder hole, 15... Main combustion chamber, 17
... Vortex chamber, 18 ... Fuel injection nozzle, 19 ...
Main nozzle hole, 19a... Inner wall surface, 20... Sub-nozzle hole, 2
0a...inner wall surface.

Claims (1)

[Scope of utility model registration request] A main combustion chamber defined in the cylinder, a swirl chamber formed in the cylinder head and having a fuel injection nozzle, a main injection hole communicating these two chambers, and a main combustion chamber extending in the axial direction of the fuel injection nozzle. In a swirl chamber type diesel engine, the swirl chamber is provided with a sub nozzle hole that communicates the swirl chamber with an end of the main nozzle hole on the main combustion chamber side, and an inner wall surface of the main nozzle hole on the side of the sub nozzle hole is connected to the inner wall surface of the main nozzle hole on the side of the sub nozzle hole. A swirl chamber type diesel engine characterized by being curved so as to be equidistant from the inner wall surface on the side of the main nozzle hole.