JPH0433991B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fuel injection nozzles for diesel engines, and more particularly to improvements in pinto-type injection nozzles.

In a swirl chamber type diesel engine or a direct injection type diesel engine in which a hemispherical combustion chamber is formed in the piston crown and the air introduced from the swirl port forms a swirl within the combustion chamber. In this case, the temperature distribution within the chamber increases toward the center due to the cooling effect of the inner wall of the swirl chamber or combustion chamber and the buoyancy effect due to centrifugal force. When the engine is operated under a light load, if fuel is injected into the high-temperature part at the center of the swirl, ignition occurs quickly, so noise can be reduced or starting can be facilitated. When the load is high, injecting the fuel along the periphery of the swirl can promote mixing of the fuel and air. In order to change the fuel injection direction according to the load in this way, a pinto nozzle has been used conventionally.

A conventional pinto nozzle has a main nozzle hole that extends parallel to the injection nozzle axis and a sub nozzle hole that is inclined with respect to the axis. It is installed to face the center. When the load is light, the lift amount of the needle valve is small, so the opening area of the main injection hole is small, and the fuel is mainly injected from the sub injection hole toward the high temperature part at the center of the swirl. When the load is high, the lift amount of the needle valve becomes large, so the fuel is mainly injected from the main injection hole toward the area around the swirl.

However, in the conventional pinto nozzle, since the sub-nozzle hole is always open, fuel is injected into the center of the swirl through the sub-nozzle even under high load. For this reason, under high load conditions, fuel gathers in the center of the swirl, resulting in insufficient mixing with air, resulting in a decrease in output and an increase in smoke.

The present invention aims to eliminate the above-mentioned inconveniences of conventional pinto nozzles, and provides an improved pinto nozzle in which fuel is not substantially injected toward the swirl center during high loads. The purpose is to

For this reason, the present invention has a main nozzle hole oriented parallel to the injection nozzle axis and a sub-nozzle hole extending obliquely with respect to the axis, so that the fuel injected from the main nozzle hole and the sub-nozzle hole are connected to each other. In a pinto-type injection nozzle in which the proportion of fuel to be injected can be changed according to the lift amount of the needle valve, a blocking means is provided to substantially block the main nozzle hole when the needle valve has a large lift. The nozzle hole and the sub nozzle hole are injected from the main nozzle hole into the center of the intake swirl formed in the engine when the needle valve lifts small, and when the needle valve lifts large, fuel is injected from the sub nozzle hole around the swirl. It is characterized by being arranged so that it is sprayed at

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

FIG. 1 is a partial view of one embodiment of a pinto nozzle improved in accordance with the present invention, the pinto nozzle 10 having a nozzle body 12 and a needle valve 14 slidably and precision fitted within its bore. Similar to conventional nozzles, the nozzle body 12 is formed with a fuel introduction passage 16 and a pressure chamber 18, and a needle pin 2 is provided at the tip of the needle valve 14.
0 is set. A main nozzle hole 22 and a sub nozzle hole 24 are provided in the lower part of the nozzle body 12. As shown, the main nozzle hole 22 extends parallel to the axis of the nozzle 10, and the axis of the sub nozzle hole 24 is inclined with respect to the nozzle axis. The secondary nozzle hole 24 has a diameter that ensures the maximum flow rate of this nozzle 10 when the main nozzle hole 22 is blocked. Further, the opening area of the main nozzle hole 22 is considerably larger than that of the sub nozzle hole 24. 2
6 is a valve seat, and 28 is a valve contact portion. At the lower part of the needle pin 20, an enlarged diameter portion 32 is formed following a tapered portion 30 that widens toward the end. The diameter of the enlarged diameter portion 32 is equal to or slightly smaller than the diameter of the main nozzle hole 22.

Therefore, when the engine is under light load, and therefore when the lift amount of the needle valve 14 is small as shown in FIG. 1, fuel is mainly injected from the main injection hole 22 having a large opening area. Although the jet of fuel passing through the main nozzle hole 22 is slightly diffused by the enlarged diameter portion 32, since the tapered portion 30 is provided, the spread angle of the fuel can be minimized.

When the engine is under high load, the lift amount of the needle valve 14 increases as shown in FIG. Therefore, as the needle valve lifts, the enlarged diameter portion 32 enters the main nozzle hole 22 and closes the main nozzle hole. Therefore, at this position, fuel is injected only from the sub injection hole 24.

The injection nozzle of the present invention is positioned in the engine so that the positional relationship of the main and sub injection holes with respect to the swirl is opposite to that of a conventional pinto nozzle. FIGS. 3 to 5 show examples of the arrangement of the improved pinto nozzle of the present invention.

Figures 3 and 4 schematically show an example in which the injection nozzle of the present invention is applied to a direct injection diesel engine equipped with a piston with a hemispherical combustion chamber, and Figure 3 shows a part of the engine. A vertical cross-sectional view, FIG. 4 is a horizontal cross-sectional view taken along the - arrow direction in FIG. In the figure, 10 represents an injection nozzle, 40 a cylinder head, 42 a cylinder block, 44 a piston, and 46 a combustion chamber. The injection nozzle of the present invention is arranged so that the spray 48 from the main nozzle hole is directed toward the center of the combustion chamber, and the spray 50 from the auxiliary nozzle hole is directed toward the periphery.

FIG. 5 schematically shows an example of application to a swirl chamber type engine, where 10 is an injection nozzle, 52 is a cylinder head, 54 is a swirl chamber, 56 is a piston, and 5 is a cylinder head.
3 represents a cylinder block. Also in this arrangement example, the arrangement is such that the spray 60 from the main nozzle hole is injected at the center of the vortex chamber, and the spray 62 from the auxiliary nozzle hole is injected at the periphery.

If the fuel is installed in this direction, the fuel is mainly injected from the main nozzle hole 22 toward the high temperature area at the center of the swirl when the load is light, so that ignition occurs quickly. During high-load operation, the main nozzle hole 22 is blocked,
Since the fuel is injected only from the sub-nozzle hole 24 to the surrounding area of the swirl, the fuel is not concentrated in the center and is sufficiently mixed with the air.

As described above, the pinto nozzle of the present invention is equipped with a means for substantially blocking the main nozzle hole when the needle valve lifts large, and this nozzle has a means for substantially blocking the main nozzle hole when the needle valve is lifted large. Since the secondary nozzle holes are arranged so as to be oriented toward the surrounding area of the swirl, the fuel is injected into the high temperature area at the center of the swirl during light loads, that is, when the needle valve has a small lift, improving ignition performance. Furthermore, when the load is high, that is, when the needle valve has a large lift, the fuel is injected around the swirl, so that sufficient mixing of fuel and air can be achieved, which has the effect of improving output and reducing smoke.

[Brief explanation of drawings]

FIGS. 1 and 2 are partial cross-sectional side views of a portion of the improved pinto nozzle of the present invention, corresponding to the needle valve positions at small lift and large lift, respectively, and FIGS. FIG. 2 is a schematic diagram showing an example of arrangement of the injection nozzle of the invention in an engine. 10... Injection nozzle, 12... Nozzle body, 14
...Needle valve, 20...Needle pin, 22...Main nozzle hole, 24...Sub-nozzle hole, 30...Tapered part, 32...Diameter enlarged part.

Claims (1)

[Claims] 1. A main nozzle hole oriented parallel to the injection nozzle axis and a sub nozzle hole extending obliquely to the axis,
In a pinto type injection nozzle in which the ratio of fuel injected from the main injection hole and fuel injected from the sub injection hole can be changed according to the lift amount of the needle valve, the main injection A blocking means is provided to substantially block the holes, and the main nozzle hole and the sub nozzle hole are injected from the main nozzle hole into the center of the intake swirl formed in the engine during a small lift of the needle valve. 1. A pinto-type injection nozzle for a diesel engine, characterized in that the fuel is injected from a sub-nozzle hole to the periphery of the swirl during a large lift. 2. The injection nozzle according to claim 1, wherein the closing means comprises an enlarged diameter portion formed at the tip of the needle pin of the needle valve and having an outer diameter approximately equal to the inner diameter of the main injection hole. 3. The injection nozzle according to claim 2, wherein the enlarged diameter portion and the needle pin are connected by a tapered portion that widens toward the end.