JPS601266Y2 - Diesel engine fuel injection nozzle - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a fuel injection nozzle for a diesel engine.

Conventionally, fuel injection nozzles for diesel engines are
For example, there is one shown in FIG.

This is called a no-throttle type and is often used in swirl chamber diesel engines.

In this throttle type injection nozzle, fuel is pumped into a fuel passage 1 from a fuel injection pump (not shown) and enters an injection valve chamber 2.
When the pressure rises to the nozzle injection start pressure, an upward force acts on the conical portion 3a of the needle valve 3, lifting the needle valve 3.

At this early stage of injection, the annular area between the tip of the needle valve 3 and the injection port 4 is small, so the amount of fuel injected is small.

When the valve lift increases, the annular area increases and main injection is performed.

(See Kyokuyo Kendo 1978 N-Publisher 1 Lecture on Internal Combustion Engines, Volume 1, pages 250 and 251.

The one shown in Figures 2A and B is a pintaux nozzle with a cutting hole 5 that performs advance injection as a noise countermeasure for diesel engines, and has been attracting attention in recent years because it also improves starting performance in cold weather. .

This nozzle injects fuel in advance from the cutting hole 5 opened near the main nozzle 4 in the early stage of fuel injection, that is, in the region where the lift of the needle valve 3 is small, and when the valve lift increases and the annular area of the main nozzle 4 increases. The main injection is performed from the main nozzle 4, and in particular, in the one shown in FIG. The system is designed to actively perform injection.

In this way, in the case where the injection is performed in advance from the cutting hole 5, the air utilization rate near the main nozzle 4 increases, so the first
It has the advantage of improved ignition performance compared to the throttle type shown in the figure.

■Yokendo Published by Showa 4 Tsubo 1 Internal Combustion Engine Lecture Volume 1 Yo No. 30
See page 0.

However, due to the advance injection from the cutting port 5, the main nozzle 4
Even though the utilization rate of the surrounding air is increased, because the cutting hole 5 has a simple hole shape, the preceding jet stream does not become a sufficiently atomized spray, and it remains a jet stream and is not mixed with air. Since mixing is not carried out sufficiently and quickly, a significant improvement in air utilization cannot be expected, and therefore it does not lead to a reduction in smoke generation.

Furthermore, since the ignition delay cannot be sufficiently shortened, the occurrence of knocking cannot be effectively prevented, and therefore, there is a problem that it is not very effective in reducing noise.

This invention was made in order to eliminate such conventional drawbacks.A groove is formed near the main nozzle, a cutting hole is opened in the groove, and a porous member is placed in the groove to cover the cutting hole. This porous member sufficiently atomizes the pre-injected fuel and expands the injection angle, significantly improving air utilization.

Hereinafter, an embodiment of this invention will be described in detail with reference to the drawings, in which the same parts as those of the conventional structure are given the same reference numerals.

That is, in the present invention, as illustrated in FIG. 3, a cutting hole 5 is opened near the main injection port 4, and fuel is injected in advance from the cutting hole 5 at the initial stage of injection. , a groove 7 is formed in the vicinity of the main nozzle 4, the cutting port 5 is opened in the groove 7, and the cutting port 5 is covered in the groove 7 with foamed metal, steel wool, sintered alloy, ceramics, etc. A porous member 8 such as the above is attached.

The above-mentioned arrangement relationship of the cutting hole 5 and the groove 7 as well as the porous member 8 is such that the groove 7 is formed concentrically in the vicinity of the main injection hole 4 and the groove 7 is formed in the groove 7 as shown in FIG. 4A. A plurality of cutting holes 5 may be opened and a porous member 8 may be attached to the grooves 7 to cover the cutting holes 5, or the grooves 7 may be made semicircular and a plurality of cutting holes 5. Alternatively, the groove 1 can be formed linearly and a plurality of cutting holes 5 can be opened in the groove 7 as shown in FIG. It can be set arbitrarily.

FIG. 5 shows the installation state of the fuel injection nozzle N having the above structure, and 9 in the figure shows the cylinder head 1. , “0
is a swirl chamber, 11 is a glow plug for starting, 1 "2i",
13 is a cylinder block, 13 is a piston, and 14 is a main fuel chamber.

Next, to explain the operation of the fuel injection nozzle N having the above configuration, the fuel pumped under pressure from the fuel pump (not shown) is sent to the passage 1.
It enters the injection valve chamber 2 through it and pushes up the needle valve 3.

During the period when the lift of the needle valve 3 is small and the flange 6 is blocking the main nozzle 4, advance injection IA is performed in which fuel is injected from the cutting hole 5 into the O swirl chamber 10. According to the invention, the cutting hole 5 opens into a groove 7 formed near the main nozzle 4, and since the cutting hole 5 is covered with a porous member 8 installed in the groove 7, this pre-injected fuel The particles are sufficiently atomized by passing through the porous member 8, and the spray is spread out in a shower-like manner.

In addition, since the injected fuel is atomized in this way, and the pressure in the injection valve chamber 2 is not high at the beginning of injection, the spray remains near the main nozzle 4, and the air near the nozzle 4 is fully utilized. This makes it possible to significantly reduce smoke generation.

Furthermore, since the air utilization rate is improved and the ignition delay is shortened in this way, the noise reduction effect is large and starting performance can also be improved.

Subsequently, when the lift amount of the needle valve 3 increases and the flange 6 opens the main nozzle 4, the passage cross-sectional area of the main nozzle 4 becomes larger than that of the cut hole 5, so that the fuel mainly flows through the main nozzle. 4 and becomes the main jet IB.

The main jet stream IB injected in this way makes full use of the air near the center of the swirl chamber 2, and stable combustion is performed.

As described above, according to this invention, the cutting hole opens into the groove formed near the main nozzle, and since this cutting hole is covered with a porous member installed in the groove, the groove is formed with porous holes. The quality material allows the injected fuel to be sufficiently atomized during advance injection, and the spray angle can be expanded, so it is mixed with the air around Keishinaku sufficiently and quickly, greatly improving the air utilization rate and producing smoke. It has excellent practical effects in that it can reduce noise, reduce noise by shortening ignition delay, and improve startability.

[Brief explanation of drawings]

Figures 1 and 2 are cross-sectional explanatory diagrams showing conventional nozzles, respectively;
Figure 3 is a cross-sectional explanatory diagram showing an example of a nozzle designed with a grommet, □ Figure 4 A, B, and C are bottom views of the nozzle showing the relationship between the main nozzle, the cutting hole, the groove, and the porous member, and Figure 5. The figure is a cross-sectional view showing the installed state of the nozzle proposed by Kome. :'1...Fuel passage, 2...Injection valve chamber, 3...Needle valve, 4...Main injection port, 5...=
...Drilling hole, 7...Groove, 8...Porous member.

Claims (1)

[Scope of utility model registration request] In a fuel injection nozzle for a diesel engine that performs preliminary injection from a cutting hole that opens near the main nozzle of the fuel injection nozzle, and performs main injection from the main nozzle following this preliminary injection, a groove is formed near the main nozzle, and the groove is formed in the vicinity of the main nozzle. A fuel injection nozzle for a diesel engine, characterized in that the cut hole is opened in the groove, and a porous member is attached to the groove to cover the cut hole.