JP2519568Y2 - Fuel injection nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a fuel injection nozzle for injecting fuel from a nozzle into a combustion chamber or the like.

[Conventional technology]

Conventionally, a fuel injection nozzle for spraying fuel into a combustion chamber has, for example, a structure shown in FIG. The fuel injection nozzle mainly includes a nozzle body 20, a plurality of injection holes 22 formed at the tip of the nozzle body 20, and a needle valve 21 for opening and closing the injection hole 22. The nozzle body 20 is made of a metal material, and is composed of a tubular body upper portion 24 and a tubular body tip portion 25 whose tip is sealed. A fuel passage 23 is formed between the inner peripheral surface of the cylindrical upper portion 24 and the outer peripheral surface of the needle valve 21. Also, the tip of the cylinder
A plurality of injection holes 22 are formed in 25. These holes
The needle valve 21 is opened and closed by the reciprocating movement of the needle valve 21 so that the tapered surface 26 at the tip of the needle valve 21 comes into contact with and separates from the valve seat portion 27 of the tubular body tip portion 25.

In addition, as a fuel injection nozzle for an internal combustion engine, Japanese Patent Laid-Open No. 2-67
There is one disclosed in Japanese Patent No. 458. In the fuel injection nozzle of the internal combustion engine, the hole of the nozzle has a shape in which the cross section of the inner end is larger than the cross section of the outer end of the hole, and the taper or step in which the holes are uniformly converged. And the two or more cylindrical parts have different cross-sections.

Further, as a nozzle injection hole in a fuel injection nozzle of an internal combustion engine, there is one disclosed in JP-A-51-101629. The nozzle nozzle hole removes the edge portion between the flow path of the nozzle hole and the wall surface of the suck hole, and connects between them with a smooth curvature.
It is more than twice and less than 1.5 times, and the length of the straight part not included in the curvature in the flow channel is 0.3 of the above diameter.
It is formed so as to remain in the range of not less than 3.5 times and not more than 3.5 times.

[Problems to be solved by the device]

By the way, in the fuel injection nozzle, the shape, the injection hole angle, the injection hole diameter, and the injection hole number of the injection hole 22 formed in the cylindrical tip portion 25 are conditions that have a great influence on the combustion state. The determination of these various conditions is an important factor for improving engine performance in relation to engine performance. In particular, it is a well-known element that the injection hole shape such as the shape and the injection hole angle has a great influence on combustion, but it is necessary to manufacture injection holes of a fine shape other than a circle, that is, an irregular shape. Was difficult. For example, by changing the shape of the injection hole of the fuel injection nozzle from a conventional circular shape to a deformed shape such as a quadrangle, it is possible to change the velocity distribution of the spray particles and improve the air intake.

However, in the fuel injection nozzle, it is not possible to increase the pressure of the injected fuel and atomize the injected fuel simply by forming the injection hole in the shape of a deformed injection hole, and also to expand the spray pattern. Therefore, it is impossible to improve the air introduction rate, that is, the air utilization rate.

Further, regarding the injection hole shape of the fuel injection nozzle disclosed in the above-mentioned JP-A-2-67458, the nozzle hole has a shape in which the cross section of the inner end is larger than the cross section of the outer end, and The holes are formed in a tapered shape that converges uniformly, but even if they are simply converged into a taper, it is not always possible to raise the fuel pressure to achieve atomization and to improve air introduction. is there.

An object of the present invention is to solve the above-mentioned problems, and in a fuel injection nozzle that injects fuel into the combustion chamber from the injection hole exposed in the combustion chamber, the injection hole is not increased without increasing the capacity of the fuel injection pump. Is changed from the inlet side to the outlet side, the input pressure to the inlet of the injection hole passes through the injection hole to increase the fuel pressure and flow velocity injected from the outlet to the combustion chamber, and To provide a fuel injection nozzle that achieves the atomization of the spray and diffuses the injection shape to improve the air utilization rate.

[Means for solving the problem]

The present invention is configured as follows to achieve the above object. That is, the present invention provides a nozzle main body having a fuel passage and an injection hole, and a needle valve that reciprocates in the nozzle main body and opens and closes the injection hole by contacting and separating from a valve seat portion formed in the nozzle main body. In the fuel injection nozzle, the injection hole cross-sectional area is gradually reduced from the inlet side on the fuel passage side to the outlet side to the outside, and the injection hole shape is changed from a circular shape on the inlet side to a flat shape on the outlet side. It relates to a modified fuel injection nozzle.

In this fuel injection nozzle, the injection hole cross-sectional area A
(X) is changed from the inlet side sectional area A to the outlet side sectional area according to the following exponential function.

A (x) = A / e ^{2bx / L} where b is a constant, L is the distance from the inlet to the outlet of the nozzle body, and x is an arbitrary distance from the inlet to the outlet of the nozzle body.

[Action]

The fuel injection nozzle according to the present invention is configured as described above and operates as follows. That is, this fuel injection nozzle has a needle body that forms a fuel passage and an injection hole, and a needle that reciprocates in the nozzle body and that opens and closes the injection hole by contacting with and separating from a valve seat portion formed in the nozzle body. In the fuel injection nozzle having the valve, the injection hole cross-sectional area is formed so as to gradually decrease from the inlet side of the fuel passage side to the outlet side to the outside, so that the fuel from the fuel passage of the nozzle main body passes from the injection hole inlet portion. The pressure is increased by passing through the injection hole having a narrowed cross-sectional area, the flow velocity is increased, and the fuel injected from the outlet into the combustion chamber becomes high-pressure injection, and atomization of the spray is promoted. Moreover, since the shape of the injection hole is changed from the circular shape on the inlet side to the flat shape on the outlet side, the injection pattern is diffused and the air utilization rate is improved.

〔Example〕

An embodiment of a fuel injection nozzle according to the present invention will be described below with reference to the drawings.

One embodiment of the fuel injection nozzle according to the present invention is
A description will be given with reference to FIGS. 2, 3 and 4. FIG. 1 is a schematic explanatory view showing this fuel injection nozzle, FIG. 2 is an enlarged explanatory view of the injection hole portion of FIG. 1, and FIG. 3 is an explanatory view showing the injection hole shape.

This fuel injection nozzle reciprocates in the nozzle body 1 in which the fuel passages 3 and 4 and the plurality of injection holes 5 are formed, and moves toward and away from the valve seat portion 9 formed in the nozzle body 1. And a needle valve 2 for opening and closing the injection hole 5, and in particular, the injection valve is formed in a shape in which the cross-sectional area of the injection hole is gradually reduced from the inlet 7 on the fuel passage 4 side to the outlet 8 to the outside. Is. The needle valve 2 that moves up and down in the nozzle body 1 moves upward with respect to the nozzle body 1 when fuel pressure is applied to the needle valve 2, and the tapered surface 10 of the needle valve 2 causes the valve seat portion of the nozzle body 1 to move. 9, the fuel passage 4 and the suck hole 6 communicate with each other, and the fuel supplied from the fuel injection pump to the fuel passage 3 is sent from the fuel passage 3 to the fuel passage 4 and the suck hole 6, and then from the injection hole 5 to the outside. That is, it is injected into the combustion chamber.

Regarding the shape of the injection hole 5 in this fuel injection nozzle, the injection hole cross-sectional area A (x) is defined as the cross-sectional area A from the inlet 7 side to the outlet 8
The cross-sectional area was changed according to the following exponential function. That is, if the distance from the inlet 7 to the outlet 8 of the nozzle body 1 is L and the arbitrary distance from the inlet 7 to the outlet 8 of the nozzle body 1 is x, then A (x) = A / e ^{2bx / L}
[However, b is a constant.

In this fuel injection nozzle, the cross-sectional area A of the injection hole 5
By changing (x) with the above exponential function, the fuel injected smoothly from the inlet 7 to the outlet 8 is caused to flow smoothly in the injection hole, and the fuel pressure and flow velocity are most effectively increased. I found out that

Furthermore, the shape of the injection hole 5 in this fuel injection nozzle is
As shown in FIG. 4 or FIG. 5, it is formed in an irregular shape.

In FIG. 4, the injection hole 5 has a circular shape 5C on the inlet 7 side.
In this example, the flat shape is changed to the flat shape 5F as it goes to the outlet 8 side, and the degree of the flat shape is increased from the intermediate portion toward the outlet 8.

Further, FIG. 5 shows an example in which the shape of the injection hole 5 is formed in a circular shape 5C on the inlet 7 side and is changed to a star-shaped flat shape 5S as it advances to the outlet 8 side.

As described above, the fuel injection nozzle has a shape in which the injection hole 5 is narrowed into an irregular shape from the inlet 7 to the outlet 8 so that the fuel supplied from the fuel passage 4 to the injection hole 5 through the suck hole 6 is formed. The fuel pressure is increased as it goes from the inlet 7 side of the injection hole 5 toward the outlet 8 side where the cross-sectional area is narrowed, and atomization is promoted by being injected from the outlet 8 of the injection hole 5. Moreover, by forming the injection hole 5 into a flat shape as shown in FIG. 4 or 5, the spray pattern is in a diffused state, and the air utilization rate in the combustion chamber is improved.

Further, the shape of the injection hole 5 is not limited to the above-mentioned shape, and for example, a deformed shape such as a quadrangle, a hole diameter, a shape change of the hole, an angle, and a size can be selected and formed in advance as desired. Is.

Therefore, this fuel injection nozzle does not need to use a high-capacity fuel injection pump, and the fuel pressure can be made high by the shape of the injection hole of the fuel injection nozzle. Therefore, use a low-pressure fuel injection pump. Thus, it is possible to secure the fuel pressure and the flow velocity equivalent to the high pressure pump.

[Effect of device]

The fuel injection nozzle according to the present invention is configured as described above and has the following effects. That is, this fuel injection nozzle has a needle body that forms a fuel passage and an injection hole, and a needle that reciprocates in the nozzle body and that opens and closes the injection hole by contacting with and separating from a valve seat portion formed in the nozzle body. In the fuel injection nozzle having the valve, since the injection hole cross-sectional area is formed so as to gradually decrease from the inlet side of the fuel passage side to the outlet side to the outside, the fuel from the fuel passage of the nozzle main body The pressure is increased by passing through the injection hole whose cross-sectional area is narrowed from the inlet, the flow velocity is increased, and the fuel injected from the outlet of the injection hole into the combustion chamber is high-pressure injection,
Atomization of the spray is promoted.

Moreover, since the shape of the injection hole is changed from the circular shape on the inlet side to the flat shape on the outlet side, the injection pattern is diffused and the air utilization rate in the combustion chamber is improved.

Therefore, if this fuel injection nozzle is used, it is possible to secure sufficient atomization and air utilization effects with a low capacity pump without increasing the capacity of the fuel injection pump.

Further, in this fuel injection nozzle, the injection hole sectional area A (x) is changed from the inlet side sectional area A to the outlet side sectional area A (x) = A / e ^{2bx / L} [where b is a constant, L The distance from the inlet to the outlet of the nozzle body, x; an arbitrary distance from the inlet to the outlet of the nozzle body], so that the fuel introduced into the injection hole smoothly flows, By making the injection holes flow, the fuel pressure and the flow velocity can be most effectively increased, and the fuel can be injected from the outlet of the injection holes into the combustion chamber.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an embodiment of the fuel injection nozzle according to the present invention, FIG. 2 is an enlarged explanatory view of the injection hole portion of FIG. 1, and FIG. 3 is an explanatory view showing an example of the injection hole shape, FIG. 4 is an explanatory view showing another example of the injection hole shape, FIG. 5 is an explanatory view showing another example of the injection hole shape, and FIG. 6 is a schematic explanatory view showing an example of a conventional fuel injection nozzle. Is. 1 ... Nozzle body, 2 ... Needle valve, 3, 4 ... Fuel passage, 5
…… Nozzle, 7 …… Nozzle entrance, 8 …… Nozzle exit, 9…
… Valve seat, 10… Tapered surface.

Claims (2)

(57) [Scope of utility model registration request] 1. A nozzle body having a fuel passage and an injection hole,
And a fuel injection nozzle having a needle valve that reciprocates in the nozzle body and opens and closes the injection hole by contacting and separating from a valve seat portion formed in the nozzle body. Fuel injection nozzle that is formed so that it gradually decreases from the side to the outside to the outlet side, and the shape of the injection hole is changed from a circular shape on the inlet side to a flat shape on the outlet side. 2. The injection hole cross-sectional area A (x) is defined as the inlet-side cross-sectional area A
2. The fuel injection nozzle according to claim 1, wherein the cross-sectional area from the outlet side to the outlet side is changed according to the following exponential function. A (x) = A / e ^{2bx / L} However, b; constant, L; distance from the inlet of the nozzle body to the outlet, x: arbitrary distance from the inlet of the nozzle body to the outlet.