JP2565470Y2 - 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 for injecting fuel into an internal combustion engine such as a diesel engine.

[0002]

2. Description of the Related Art In general, a fuel injection nozzle includes a nozzle body 1 and a valve body 2 as shown in FIG. Inside the nozzle body 1, a hole 11 extending on the axis L is formed. The rear end (upper end in FIG. 3) of the hole 11 is connected to a fuel pool (not shown), and the front end is connected to a tapered valve seat 12. Further, the nozzle body 1 is formed with an injection hole 13 having one end opened to the valve seat 12 and the other end opened to the outer surface of the nozzle body 1. A tapered portion 14 is formed on the outer peripheral surface of the nozzle body 1 where the injection hole 13 opens.

The valve body 2 is movably inserted into the hole 11, and a tapered valve portion 21 corresponding to the valve seat 12 is formed at the tip (lower end in FIG. 3). I have. The valve body 2 is seated on the valve seat 12 by a nozzle spring (not shown). And the valve body 2
The injection hole 13 is closed by sitting on the valve seat 12. At this time, the valve portion 21 covers the valve seat 12. On the other hand, when the pressure of the fuel fed to the fuel reservoir becomes equal to or higher than a predetermined pressure, the valve body 2 lifts against the urging force of the nozzle spring and opens the injection hole 13. When the injection hole 13 is opened, fuel is injected from there into the combustion chamber of the engine.

In the conventional fuel injection nozzle, the tapered portion 14 near the position A (hereinafter referred to as the rear end position) located at the rearmost end in the axial direction of the nozzle body 1 in the opening edge of the injection hole 13. There was a problem that carbon was deposited on the steel. In order to solve such a problem, Japanese Unexamined Utility Model Publication No. Sho 59-139578 has been proposed. The fuel injection nozzle described in this publication has an injection hole 1
In view of the fact that carbon is deposited near the rear end point A because the angle θ ₁ formed between the tapered portion 3 and the tapered portion 14 is an obtuse angle, as shown by the imaginary line in FIG. A surrounding tapered recess 15 is formed, and the angle θ ₂ between the tapered surface of the recess 15 and the injection hole 13 is made an acute angle.

[0005]

However, even in the above-mentioned publication, it was not possible to sufficiently prevent carbon from adhering to the tapered portion 14 near the rear end portion A.

Accordingly, the inventor of the present application has conducted intensive studies to solve the above-mentioned problems. There was found.

That is, in a normal fuel injection nozzle, the angle θ ₁ between the injection hole 13 and the tapered portion 14 is an obtuse angle. When the angle θ ₁ is an obtuse angle, the rear end portion A of the opening edge of the injection hole 13 in the tapered portion 14 is located on the most forward side with respect to the injection direction of the injection hole 13, and in the axial direction of the nozzle body 1. The position B located at the most distal end (hereinafter referred to as the distal end position) is located at the most rearward position. In such a positional relationship, when the fuel is injected from the injection hole 13, the fuel first separates from the front end point B of the opening edge of the injection hole 13 and finally separates from the rear end point A. In addition, when the fuel is separated from the tip portion A, the fuel is blown up by the combustion gas from the combustion chamber. Therefore, the fuel adheres to the tapered portion 14 near the rear end portion A.
In this case, there is no problem if the attached fuel is completely burned,
The vicinity of the rear end location A is blocked by the injected fuel against the heat of the combustion chamber. For this reason, the attached fuel was incompletely burned to become carbon, and was deposited near the rear end portion A.

The present invention has been made based on the above findings, and reduces the deposition of carbon in the vicinity of the most rear end side of the opening edge of the injection hole in the axial direction of the nozzle body. It is an object of the present invention to provide a fuel injection nozzle capable of performing the above.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, a valve seat is formed inside a distal end portion, and an injection hole extending from the valve seat to an outer peripheral surface is provided. A nozzle body formed, and a valve body movably provided inside the nozzle body, which opens and closes the injection hole by being seated and lifted on the valve seat, wherein the valve body is provided with the valve seat. In a fuel injection nozzle configured to inject fuel from the injection hole when lifted from, the valve seat is formed so as to be tapered from a rear end side of the nozzle body toward a front end side, and the valve body includes: The nozzle portion has a tapered shape corresponding to the valve seat, forms a valve portion that covers the injection hole when seated on the valve seat, and includes the nozzle of the outer peripheral surface of the nozzle body at the outer opening edge of the injection hole. Body The position located on the rearmost end side in the linear direction (hereinafter, referred to as the rear end position) is located rearward in the injection direction from the position located on the most distal end side in the axial direction of the nozzle body (hereinafter, referred to as the distal end position). And the distance from the axis of the nozzle body to the rear end is set equal to or less than the distance from the axis of the nozzle body to the front end. According to the second aspect of the present invention, a valve body is formed inside a distal end portion and an injection hole extending from the valve seat to an outer peripheral surface is formed. And a valve element that opens and closes the injection hole by seating and lifting on the valve seat, and injects fuel from the injection hole when the valve element lifts from the valve seat. In the fuel injection nozzle, a portion (hereinafter, referred to as the rearmost end in the axial direction of the nozzle body) of the outer opening edge of the injection hole on the outer peripheral surface of the nozzle body.
It is called the trailing edge. ) Is located on the rear side in the injection direction from a position located at the most distal end side in the axial direction of the nozzle body (hereinafter, referred to as a distal end position), and
The distance from the axis of the nozzle body to the rear end portion is shorter than the distance from the axis of the nozzle body to the front end portion.

[0010]

In the invention according to the first aspect, the rear end portion of the opening edge of the injection hole on the outer peripheral surface of the nozzle body is located on the rear side in the injection direction from the front end portion. Separate from the rear end and finally separate from the front end. Therefore, even if the fuel is blown up by the combustion gas, the fuel hardly adheres to the outer peripheral surface of the nozzle body near the rear end portion, and the carbon deposition is reduced. In addition, the distance from the rear end of the opening edge of the injection hole to the axis of the nozzle body is equal to or less than the distance from the front end to the axis of the nozzle body. The effect of the combustion gas blowing up is reduced. Therefore, carbon deposition near the rear end portion is further reduced. In the invention according to claim 2, since the distance from the rear end of the opening edge of the injection hole to the axis of the nozzle body is shorter than the distance from the front end to the axis of the nozzle body,
The effect of the combustion gas blowing up on the fuel injected from the rear end portion is further reduced. Therefore, carbon deposition near the rear end portion is further reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The same parts as those in the above-described conventional example are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 shows an embodiment of the present invention. In the fuel injection nozzle of this embodiment, a cylindrical portion 16 is formed at a portion where the injection hole 13 opens at the rear end of the tapered portion 14 in the axial direction of the nozzle body 1. The cylindrical portion 16 extends parallel to the axis L of the nozzle body 1.

Here, the cylindrical portion 16 is parallel to the axis L of the nozzle body 1, and the injection holes 13 are inclined so as to go toward the axial end of the nozzle body 1 from the inside to the outside. Therefore, of the opening edges of the injection holes 13 on the outer peripheral surface of the cylindrical portion 16, a position (hereinafter, referred to as a rear end position) C located at the rearmost end in the axial direction of the nozzle body 1 is the most in the fuel injection direction. A position D located on the rear side and located at the most distal end in the axial direction of the nozzle body 1 (hereinafter referred to as a distal end position) is located most forward in the ejection direction. Further, since the outer peripheral surface of the cylindrical portion 16 is parallel to the axis of the nozzle body 1, the distance from the axis L to the rear end point C and the distance to the front end point D are equal.

In the fuel injection nozzle having the above structure, when fuel is injected from the injection hole 13, the rear end portion C is located at the rearmost position in the injection direction, and the front end portion D is located at the most forward position in the injection direction. Therefore, the fuel injected from the injection hole 13 first separates from the rear end portion C, and finally separates from the front end portion D. Therefore, the fuel hardly adheres to the rear end portion C. Moreover, since the distance from the rear end portion C to the axis L is equal to the distance from the front end portion D to the axis L, the rear end portion of the combustion gas that blows up from the front end side to the rear end side of the nozzle body 1 The effect on fuel injected from near C is reduced. Therefore, carbon deposited on the outer peripheral surface of the cylindrical portion 16 near the rear end portion C can be reduced. In this case, instead of the cylindrical portion 16,
By forming a tapered portion having a gradually decreasing diameter from the front end side to the rear end side of the nozzle body 1, the influence of the combustion gas on the fuel injected from the vicinity of the rear end portion C is further reduced, and the carbon is deposited. Can be further reduced. Therefore, it is desirable to do so.

The fuel injected from the injection hole 13 is
Since it is finally separated from the tip D of the opening edge of the injection hole 13, if there is no combustion gas blowing up,
The fuel adheres near the tip D. However, the tip D
The fuel that is to be attached to the vicinity is injected together with other fuel without being attached to the vicinity of the front end portion D due to the rising of the fuel gas. Further, even if the fuel adheres to the vicinity of the tip portion D, the adhered fuel is completely burned by the heat of the combustion chamber. Therefore, the tip location D
No carbon is deposited in the vicinity.

FIG. 2 shows an embodiment of the second aspect of the present invention. In place of the tapered portion 14 and the cylindrical portion 16, a spherical portion 1 having a center O on the axis L of the nozzle body 1 is shown.
7 and the center O of the spherical portion 17 is
7 is located on the tip side in the axial direction of the nozzle main body 1 from the opening of the injection hole 13 on the outer peripheral surface of the nozzle body 7. Therefore, in this embodiment, similarly to the above-described embodiment, the spherical portion 17 is provided.
In the opening edge of the injection hole 13 at the rear end portion E located at the rearmost end in the axis main body of the nozzle main body 1 is positioned at the rearmost side in the fuel injection direction,
Is located at the most distal end side in the axial direction, and is located at the most forward side in the injection direction. In addition, the distance from the rear end to the axis L is shorter than the distance from the front end F to the axis L. Therefore, in this embodiment, the amount of carbon deposited near the rear end portion E can be further reduced.

Note that the present invention is not limited to the above-described embodiment, but may be made within the scope of the invention.
It can be changed as appropriate. For example, the above-described embodiment is applied to a fuel injection nozzle of a type in which the opening inside the injection hole 13 is directly closed by the valve body 2, but can be applied to other fuel injection nozzles. .

In the above embodiment, not only the portion of the outer peripheral surface of the nozzle body 1 where the injection hole 13 is opened but also a cylindrical surface or a spherical surface is formed over the entire circumference including the opening. End point C (E) to end point D
(F) Although it is located on the rear side in the injection direction, a new surface may be formed only in the portion including the opening of the injection hole 13 in order to do so.

[0019]

As described above, according to the first aspect of the present invention, the rear end portion of the opening edge of the injection hole is located on the rear side in the injection direction from the front end portion, and from the rear end portion. Since the distance to the axis of the nozzle body is equal to or less than the distance from the tip to the axis, the effect of reducing the amount of carbon deposited near the rear end of the opening edge of the injection hole can be reduced. can get. Also,
According to the second aspect of the invention, the distance from the rear end to the axis of the nozzle body is shorter than the distance from the front end to the axis, so that the amount of deposited carbon can be further reduced. Is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a main part of an example of a conventional fuel injection nozzle.

[Explanation of symbols]

Reference Signs List 1 Nozzle body 13 Injection hole 16 Cylindrical portion 17 Sphere portion C Rear end portion (the portion of the opening edge of the injection hole located at the rearmost end in the axial direction of the nozzle body) D Tip portion (the opening edge of the injection hole E A rear end portion (a portion located at the most rear end side in the axial direction of the nozzle body of the opening edge of the injection hole) F A front end portion (a portion located at the most front end side in the axial direction of the nozzle body) Of the opening edge of the nozzle located at the most distal end side in the axial direction of the nozzle body)

Claims (2)

(57) [Scope of request for utility model registration] 1. A valve seat is formed inside a distal end portion.
Formed an injection hole extending from this valve seat to the outer peripheral surface.
Nozzle body and movably provided inside this nozzle body
By sitting and lifting against the valve seat
A valve body for opening and closing the injection hole, wherein the valve body is
In a fuel injection nozzle configured to inject fuel from the injection hole when lifted from a seat, the valve seat is connected to the nozzle.
The tip of the chisel is tapered from the rear end to the front end.
And the valve body corresponds to the valve seat.
Tapered, and when the valve seats,
A valve portion is formed to cover the injection hole, and is provided on the outer peripheral surface of the nozzle body.
Of the outer opening edge of the injection hole at the most rear end side in the axial direction of the nozzle body (hereinafter, referred to as the
It is called the trailing edge. ) Is located on the rear side in the injection direction from a position located at the most distal end side in the axial direction of the nozzle body (hereinafter, referred to as a distal end position);
A fuel injection nozzle wherein the distance from the axis of the nozzle body to the rear end is equal to or less than the distance from the axis of the nozzle body to the front end. 2. A valve seat is formed inside the distal end portion.
Formed an injection hole extending from this valve seat to the outer peripheral surface.
Nozzle body and movably provided inside this nozzle body
By sitting and lifting against the valve seat
A valve body for opening and closing the injection hole, wherein the valve body is
A fuel injection nozzle configured to inject fuel from the injection hole when lifted from a seat ,
A portion (hereinafter, referred to as a rear end portion) located at the rearmost end in the axial direction of the nozzle main body in the outer opening edge of the injection hole on the outer peripheral surface is located at the most distal end side in the axial direction of the nozzle main body. It is located on the rear side in the injection direction from the location (hereinafter, referred to as the tip location),
A fuel injection nozzle characterized in that the distance from the axis of the nozzle body to the rear end is shorter than the distance from the axis of the nozzle body to the front end.