JP3334472B2 - Fuel injection nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection nozzle used for a vehicle diesel engine.

[0002]

2. Description of the Related Art A fuel injection nozzle used in a diesel engine for a vehicle has a plurality of fuel injection holes at the tip of a nozzle body, and sprays fuel from these fuel injection holes into a combustion chamber of the diesel engine. It is configured as follows.

Accordingly, the performance of a diesel engine of such a fuel injection nozzle is greatly affected by the diameter of the fuel injection hole. When the diameter of the fuel injection hole is reduced, fuel having a fine particle diameter is sprayed into the combustion chamber of the diesel engine. As a result, the air and the fuel are well mixed, thereby suppressing the generation of flue gas. However, on the other hand, increasing the number of orifices will increase nitrogen oxides, and reducing the number of orifices will lengthen the fuel injection period more than necessary, increasing fuel efficiency in high load areas with a large amount of fuel supply. (Getting worse.

[0004] In order to solve such a problem, a fuel injection nozzle has been devised in which small-diameter fuel injection holes and large-diameter fuel injection holes are alternately arranged at the tip end of the nozzle body (particularly). See Japanese Unexamined Patent Publication No. Hei 6-307311).

According to such a fuel injection nozzle, the fuel injection period does not become unnecessarily long unlike the above-mentioned conventional fuel injection nozzle, so that an increase in fuel consumption can be avoided. Had.

[0006]

That is, in the above-described fuel injection nozzle, the fuel particles sprayed from the fuel ejection hole having a small diameter are finer, but the fuel particles sprayed from the fuel ejection hole having a large diameter are fine. Therefore, there is a problem that the time until ignition becomes longer, the fuel burns independently of each other, the initial combustion amount increases, nitrogen oxides are easily generated, and the combustion noise increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to prevent the fuel injection period from becoming unnecessarily long even in a high load region where a large amount of fuel is supplied. It is an object of the present invention to provide a fuel injection nozzle capable of suppressing generation of fuel and reducing combustion noise.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 has a plurality of fuel ejection holes at a tip end portion of a nozzle body, and the fuel ejection holes are provided from these fuel ejection holes. a fuel injection nozzle for spraying fuel into said fuel ejection hole, consists of a main ejection hole and the small diameter of the secondary ejection holes of a large diameter, the main jet holes is the its central axis nozzle
Provided at a point passing through the center of the reel body, said secondary fuel jets is the
The main jet that is displaced from the main jet in the circumferential direction of the nozzle body
At a point close to the hole, it is installed as a pair with the main ejection hole.
In order to ignite the fuel from the main orifice using the fuel from the sub orifice as an ignition source, the sub orifice is
The central axis of the main ejection hole is paired with the sub ejection hole.
Of the center axis, the main
Intersects with the central axis extending to the side opposite to the side where the vent is located
It is characterized by being provided .

According to a second aspect of the present invention, in the first aspect of the present invention, the angle at which the central axis of the main ejection hole intersects with the central axis of the sub ejection hole is set to 10 ° to 30 °. Is what you do. According to a third aspect of the present invention, in the first aspect, the ratio of the diameter of the main ejection hole to the diameter of the sub ejection hole is set to 0.3 to 0.6.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a fuel injection nozzle according to an embodiment of the present invention. As shown in FIG. 1, a needle valve 2 is accommodated in a nozzle body 1 of the fuel injection nozzle. The needle valve 2 is movable in the axial direction of the nozzle body 1 by a predetermined distance, and the lower end of the pressure rod 3 is in contact with the upper end thereof.

The pressure rod 3 has a tip portion (valve portion) 2a of the needle valve 2 and a valve seat 4 formed on the nozzle body 1.
And is urged downward from the pressure springs 5 and 6 housed in the nozzle body 1.

The nozzle body 1 has a fuel supply port 7 for supplying high-pressure fuel from a fuel injection pump into the nozzle body 1, and high-pressure fuel is supplied from the fuel supply port 7 into the nozzle body 1. Then, the needle valve 2 is pushed upward by the liquid pressure of the high-pressure fuel, and the tip 2 a of the needle valve 2 is separated from the valve seat 4. And
When the distal end portion 2a of the needle valve 2 is separated from the valve seat 4, high-pressure fuel flows into the distal end portion 1a of the nozzle main body 1, and a plurality of fuel ejection holes 8 provided in the distal end portion 1a of the nozzle main body 1.
(See FIG. 2), the fuel is sprayed into the combustion chamber of the diesel engine.

As shown in FIG. 3, the fuel outlets 8 (hereinafter referred to as main outlets) are formed at equal intervals in the circumferential direction of the nozzle body 1, and the vicinity of each of the main outlets 8 is formed. Are provided with fuel sub-injection holes 9 (hereinafter referred to as sub-injection holes). These sub-ejection holes 9 have a diameter of 0.3 × d to 0.6 × d, where d is the diameter of the main ejection hole 8 (= 0.2 mm to 0.4 mm). The axis 9a is θ = 10 ° with the center axis 8a of the main ejection hole 8.
They cross at an angle of 30 °.

The main ejection hole 8 is formed so that its center axis 8a passes through the center O of the nozzle body 1. The center axis 8a of the main ejection hole 8 and the center axis 9a of the sub-ejection hole 9 are aligned with the center of the nozzle body 1. It is intersect at a position deviated from O.

In such a configuration, when high-pressure fuel is supplied from the fuel supply port 7 into the nozzle body 1, the needle valve 2 is pushed upward by the liquid pressure of the high-pressure fuel, whereby the tip of the needle valve 2 2 a is separated from the valve seat 4. When the distal end portion 2a of the needle valve 2 is separated from the valve seat 4, high-pressure fuel flows into the distal end portion 1a of the nozzle body 1 and a plurality of main ejection holes 8 provided in the distal end portion 1a of the nozzle body 1. The fuel is sprayed into the combustion chamber of the diesel engine from the sub-injection holes 9 provided near the main injection holes 8.

At this time, the fuel particles sprayed from the sub-injection holes 9 into the combustion chamber of the diesel engine have a particle diameter that is reduced to the particle diameter of the fuel particles sprayed from the main injection holes 8 into the combustion chamber of the diesel engine. Because it is finer than
The fuel is ignited before the fuel particles sprayed from the main ejection holes 8 into the combustion chamber of the diesel engine. As a result, the fuel particles sprayed from the sub-jet holes 9 form a combustion flame near the fuel particles sprayed from the main jet holes 8. This becomes the kind of fire and the fuel particles sprayed from the main jet holes 8. Will ignite.

Therefore, in one embodiment of the present invention, the time until ignition can be shortened, and the initial combustion amount does not increase, thereby suppressing the generation of nitrogen oxides and the increase in combustion noise. be able to. Further, in one embodiment of the present invention, since the fuel is sprayed from both the main ejection hole 8 and the sub-ejection hole 9, the fuel injection period becomes longer than necessary even in a high load region where the fuel supply amount is large. Not even.

FIG. 4 shows that the angle θ at which the center axis 8a of the main ejection hole 8 and the center axis 9a of the sub ejection hole 9 intersect is 10 °, 20 °.
FIG. 5 is a diagram showing the relationship between the generation amount of nitrogen oxides (NOx) and fuel consumption (be) when the angle is set to 0 ° and 30 °, and as shown in FIG. Orifice 9
Is set at θ = 10 °, the generation amount of nitrogen oxides is minimized, but disadvantageous in terms of fuel efficiency. When the angle θ is set to θ = 30 °, fuel efficiency is improved as compared with the case where θ = 10 °, but the amount of generated nitrogen oxides is increased. Therefore, in consideration of fuel efficiency, it is preferable to set the angle θ at which the center axis 8a of the main ejection hole 8 intersects with the center axis 9a of the sub ejection hole 9 to θ = 10 ° to 30 °.

FIGS. 5 and 6 show the main ejection port 8 and the sub ejection port 9.
Of Nitrogen Oxide, Fuel Efficiency and Exhaust Gas (R) when the Pore Size Ratio with
In the figure, the white circles in the figure show the experimental results when fuel was sprayed only from the main ejection holes 8, and the black squares in the figure show the results from the main ejection holes 8 and the sub-ejections. The experimental result when the hole diameter ratio with the hole 9 is set to 0.27 is shown.
The black circles in the figure indicate the main ejection holes 8 and the sub ejection holes 9.
The experimental results when the hole diameter ratio between the main ejection holes 8 and the sub ejection holes 9 are set to 0.67 are shown by black triangles in the figure. The results are shown.
As is clear from FIGS. 5 and 6, when the hole diameter ratio between the main ejection hole 8 and the sub ejection hole 9 is set to 0.67, the main ejection hole 8
The fuel consumption (be) is deteriorated and the exhaust gas (smoke emission) is increased as compared with the case where the hole diameter ratio of the gas and the sub-injection hole 9 is set to 0.27 and 0.4. Therefore, in consideration of fuel efficiency and exhaust gas, the hole diameter ratio between the main ejection hole 8 and the sub ejection hole 9 is set to 0.3.
Preferably, it is set to 0.6.

FIG. 7 shows that the angle θ at which the central axis 8a of the fuel ejection hole 8 and the central axis 9a of the fuel sub-ejection hole 9 intersect is 10 degrees.
°, 15 °, 20 °, is a diagram showing the combustion noise when set to 30 °, respectively, as is clear from the figure,
By setting the angle θ at which the central axis 8a of the fuel ejection hole 8 intersects with the central axis 9a of the fuel sub-ejection hole 9 to 10 ° to 30 °, combustion is performed as compared to when fuel is sprayed only from the fuel ejection hole 8. Noise is reduced.

Accordingly, in one embodiment of the present invention, the fuel injection period does not become unnecessarily long, the generation of nitrogen oxides can be suppressed, and the combustion noise can be reduced.

Further, in one embodiment of the present invention, the center axis 8a of the fuel ejection hole 8 and the center axis 9a of the fuel sub-ejection hole 9 intersect at a position deviated from the center O of the nozzle body 1, so that the fuel It is also possible to prevent adverse effects due to the molten base material generated when the ejection holes 9 are formed by laser processing.

In the above-described embodiment of the present invention, the fuel sub-ejection hole 9 is provided on the same horizontal plane as the fuel ejection hole 8, but the fuel sub-ejection hole 9 is located near the upper portion or the lower portion of the fuel ejection hole 8. , The same effect can be obtained.

[0024]

As described above, according to the first aspect of the present invention, the fine particles ejected from the small-diameter sub-ejection hole first burn and become a fire, and the main ejection hole and the sub-ejection hole are formed. Are brought close to each other, so that the ignitability of the fuel injected from the main ejection hole by the flame of the fire is improved, and as a result, the generation of nitrogen oxides is suppressed and the combustion noise can be reduced. In addition, since the central axis of the main ejection hole and the central axis of the sub ejection hole intersect inside the nozzle body, fuel injection from the sub ejection hole does not hinder fuel injection from the main ejection hole. Smoke emission can be reduced by effectively using indoor air.

According to the second aspect of the present invention, the above-mentioned effects can be obtained remarkably, the generation of nitrogen oxides can be further suppressed, and the combustion noise can be reduced. According to the third aspect of the invention, by setting the ratio of the diameter of the main ejection hole to the diameter of the sub-ejection hole to 0.3 to 0.6, it is possible to more reliably suppress the generation of nitrogen oxides and combust. Noise can be more reliably reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a fuel injection nozzle according to one embodiment of the present invention.

FIG. 2 is a detailed view of a portion A shown in FIG.

FIG. 3 is a sectional view taken along the line BB of FIG. 2;

FIG. 4 is a diagram showing experimental results when the angles at which the central axis of the main ejection port and the central axis of the sub ejection port intersect are set to 10 °, 20 °, and 30 °.

FIG. 5 is a diagram showing experimental results when a hole diameter ratio between a main ejection hole and a sub ejection hole is set to 0.27.

FIG. 6 is a diagram showing experimental results when the hole diameter ratio between the main ejection hole and the sub ejection hole is set to 0.4 and 0.67.

FIG. 7 is a diagram showing combustion noise when the angles at which the center axis of the main ejection hole and the center axis of the sub ejection hole intersect are set to 10 °, 20 °, and 30 °.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Nozzle body 2 ... Needle valve 3 ... Pressure rod 4 ... Valve seat 5, 6 ... Pressure spring 7 ... Fuel injection port 8 ... Main ejection hole 9 ... Sub ejection hole

────────────────────────────────────────────────── ─── Continued on the front page Examiner Shoji Iwase (56) References JP-A-7-208303 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02M 61/18 320

Claims (3)

(57) [Claims] 1. A fuel injection nozzle having a plurality of fuel ejection holes at a tip end of a nozzle body and spraying fuel from these fuel ejection holes into a combustion chamber of a diesel engine, wherein the fuel ejection hole has a large diameter. It consists of a main ejection hole and the small diameter of the secondary fuel jets, said main ejection hole has its central axis the nozzle present
Provided at a point passing through the center of the body, the secondary fuel jets are main injection
The main ejection hole which is displaced from the ejection hole in the circumferential direction of the nozzle body;
At a point close to the main outlet, a pair is provided.
In order to ignite the fuel from the main orifice with the fuel from the sub orifice as a fire, the sub orifice is formed therein.
The center axis of the main outlet is paired with the sub outlet.
Of the axis, the main jets sandwich the center of the nozzle body.
Cross the center axis extending to the opposite side of the hole
A fuel injection nozzle characterized in that it is provided with a fuel injection nozzle. 2. The fuel injection nozzle according to claim 1, wherein an angle at which a center axis of the main ejection hole and a center axis of the sub ejection hole intersect is set to 10 ° to 30 °. 3. The fuel injection nozzle according to claim 1, wherein a ratio of a diameter of the main ejection hole to a diameter of the sub ejection hole is set to 0.3 to 0.6.