JPH08338343A - Fuel injection nozzle - Google Patents

Abstract

PURPOSE: To enhance a fuel efficiency by changing the direction of fuel injection during the period of one time injection. CONSTITUTION: The outer circumferential surface of a needle valve 8 to which a nozzle hole 8b is opened, is formed with a notch part 15. The notch part 15 is disposed as to be piled up over a part of the nozzle hole 8. The depth of the notch part 15 is gradually deepened as the notch part 15 goes up to its upper side from its lower side. The formation of the notch part 15 as mentioned above allows the length of the nozzle hole 8b from its end periphery at the inner side to its end periphery at the outer side to be made short in the side part at the upper side of the nozzle hole 8b, and long in the side part at the lower side of the nozzle.

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 in an internal combustion engine such as a diesel engine.

[0002]

2. Description of the Related Art Generally, in a fuel injection nozzle used in an internal combustion engine, a needle valve lifts from a valve seat and opens when the pressure of the fuel pumped to the fuel injection nozzle reaches a predetermined valve opening pressure. Is injected from the injection hole into the combustion chamber of the internal combustion engine (see Japanese Utility Model Publication No. 60-14932 and Japanese Patent Application Publication No. 62-20671).

When injecting fuel into the combustion chamber of an internal combustion engine, in order to improve the combustion efficiency of the fuel, the fuel is injected into each part of the combustion chamber so that the air in the combustion chamber can be used as much as possible. It is desirable to do. As one method for that purpose, changing the fuel injection direction during one injection period is conceivable.

[0004]

However, in the conventional fuel injection nozzle, the injection direction of fuel is constant, and the injection direction cannot be changed during one injection period. Therefore, it is difficult to improve the combustion efficiency of fuel.

[0005]

In order to solve the above-mentioned problems, the invention according to claim 1 is such that when the pressure of the fuel to be pumped reaches a predetermined pressure, the needle valve lifts from the valve seat and opens. Then, in the fuel injection nozzle that injects fuel from the injection hole, by notching the outer surface where the injection hole opens,
It is characterized in that the length from the inner edge of the injection hole to the outer edge is different between one side portion and the other side portion of the injection hole. In this case, the location where the length from the inner edge to the outer edge of the injection hole is different may be one side portion and the other side portion in the direction substantially along the lift direction of the needle valve. Alternatively, the one side portion and the other side portion in the direction substantially orthogonal to the lift direction of the needle valve may be provided.

[0006]

When the pressure of the fuel to be pumped reaches a predetermined valve opening pressure, the needle valve lifts from the valve seat and opens to inject fuel from the injection hole. Here, at the beginning of valve opening when the pressure of the fuel to be pumped is low, the fuel flows along the inner surface of each portion of the injection hole. Therefore, the fuel is injected substantially along the axis of the injection hole. On the other hand, when the pressure of the fuel to be pumped becomes high, the fuel flows along the inner surface of the injection hole at the side portion where the length from the inner edge to the outer edge of the injection hole is long. Therefore, the injection direction of the fuel injected from the side portion hardly changes. However, when the fuel flows through the injection hole in the side portion having a short length, the fuel gradually separates from the inner surface of the injection hole from the inner edge to almost the center of the length of the injection hole. Thereafter, the fuel gradually approaches the inner surface of the injection hole, contacts the inner surface at the outer edge of the injection hole, and is directly injected from the injection hole. As a result, the fuel is injected in the direction away from the axis of the injection hole on the short side portion. Such an operation is the same in the invention according to claim 2 or 3.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.
This will be described with reference to 0. The embodiment shown in FIGS. 1 to 3 is an application of the present invention to a poppet type fuel injection nozzle 1. Of course, the present invention can be applied to other fuel injection nozzles such as a suck type.

As shown in FIG. 2, the fuel injection nozzle 1 is
A nozzle holder 2 having a cylindrical shape is provided. A joint 3 is fixed to the upper end surface of the nozzle holder 2 by a nut 4. On the other hand, the nozzle body 5 is fixed to the lower end surface of the nozzle holder 2 by a nut 6.

Inside the nozzle body 5, there is formed a valve sliding hole 5a penetrating from the upper end surface to the lower end surface thereof. A fuel reservoir 5b is formed in the middle of the valve sliding hole 5a. Fuel is pumped to the fuel reservoir 5b from a fuel passage 7 formed over the joint 3, the nozzle holder 2, and the nozzle body 5. Further, a tapered valve seat 5c is formed on the lower end surface of the nozzle body 5 where the valve sliding hole 5a is opened.

A needle valve 8 is slidably provided in the valve sliding hole 5a. A valve portion 8a seated on the valve seat 5c is formed at a lower end portion of the needle valve 8 protruding from the valve sliding hole 5a. The outer end of the injection hole 8b is opened on the outer peripheral surface of the needle valve 8 adjacent to the valve portion 8a. The inner end of the injection hole 8b is open to the inner peripheral surface of the fuel hole 8c and communicates with the fuel reservoir 5b through the fuel hole 8c. Although three injection holes 8c are formed at equal intervals in the circumferential direction of the needle valve 8 in this embodiment, one, two, or four or more injection holes 8c may be formed.

In the above structure, when the pressure of the fuel pumped to the fuel reservoir 5b reaches a predetermined initial valve opening pressure, the needle valve 8 lifts against the first nozzle spring 9. Then, when lifted by a predetermined initial lift amount, the upper spring receiver 10 hits the second nozzle spring 12 via the lift restricting member 11, and the needle valve 8 temporarily stops. At this initial lift position, the injection hole 8b is not exposed from the valve sliding hole 5a, but the fuel pressure-fed to the injection hole 8b is transferred to the inner peripheral surface of the valve sliding hole 5a and the outer peripheral surface of the needle valve 8. Between the valve seat 5c and the valve portion 8a.

When the fuel pressure further rises and reaches a predetermined main valve opening pressure, the needle valve 8 begins to lift again against the first nozzle spring 9 and the second nozzle spring 12. Then, when the lift restricting member 11 abuts the lower spring receiver 14 via the shim 13 by lifting a predetermined total lift amount, the needle valve 8 stops. In this full lift position,
As shown in (A), the injection hole 8b is exposed from the valve sliding hole 5a, and the fuel is directly injected from the injection hole 8b to the outside.

The above structure is similar to that of the conventional fuel injection nozzle. Therefore, after the needle valve 8 is fully lifted, the fuel is only injected substantially along the axis of the injection hole 8b, and the injection direction does not change.

Therefore, in the fuel injection nozzle 1, the notch 15 is formed on the outer peripheral surface of the needle valve 8.
The cutout portion 15 extends in the left-right direction along an imaginary tangent line that is in contact with the outer peripheral surface of the needle valve 8 at the opening of the injection hole 8b, and except for a portion below the opening of the injection hole 8b. It is arranged so that it overlaps the part. In addition, the depth of the cutout portion 15 is upward (the direction opposite to the lift direction, that is, the seating direction).
It is getting deeper as you go to. By forming the cutout portion 15, the length along the axis L from the inner edge of the injection hole 8b to the outer edge is
If the length of the upper side portion is L ₁ and the length of the lower side portion is L ₂ , then L ₁ <L ₂ .

The lengths L ₁ and L ₂ are determined as follows. That is, it is assumed that the fuel pressure immediately after the needle valve 8 is fully lifted is P ₀ and then rises to the maximum pressure P _max . In such a pressure change range, until the fuel pressure reaches P ₁ (P ₀ <P ₁ <P _max ), FIG.
As shown in, the fuel flows along the entire inner surface of the injection hole 8b. When the fuel pressure exceeds P ₁ , as shown in FIG. 3 (B), the fuel flows along the inner surface of the injection hole 8b at the lower side portion of the injection hole 8b, but at the upper side of the injection hole 8b. In the portion, the fuel is gradually separated from the inner surface of the injection hole 8b up to the central portion of the injection hole 8b, and when it exceeds the central portion, the separated flow gradually approaches the inner surface of the injection hole 8b and contacts the inner surface at the outer edge. It flows. In this way, the lengths L ₁ and L ₂ are determined so that the fuel flow in the injection hole 8b changes according to the fuel pressure. This determination is based on fuel pressures P ₀ , P _max ,
The experiment is performed based on the viscosity and the like.

In the fuel injection nozzle 1 having the above structure,
After the needle valve 8 is fully lifted, the fuel flows along the entire inner surface in the injection hole 8b until the fuel pressure reaches the pressure P ₁ .
Therefore, the fuel is injected from the injection hole 8b substantially along the axis L (actually, it spreads slightly). However, when the fuel pressure exceeds the pressure P ₁ , the fuel is injected along the axis L on the lower side portion of the injection hole 8b, but the fuel flows as a separated flow on the upper side portion, The fuel injected from the upper side portion is injected in a direction away from the axis L upward as the fuel advances. As a result, the entire fuel is injected upward as compared to the beginning of the entire lift, and the injection direction changes.

Next, another embodiment of the present invention will be described. In the following embodiments, only the structure different from the above embodiments will be described.

In the embodiment shown in FIG. 4, the notch 15
Are arranged so as to overlap the entire opening of the injection hole 8b. Further, the depth of the notch 15 is constant on the upper side portion of the injection hole 8b. A small recess 16 is formed below the notch 15 so as to be continuous therewith. The small recess 16 is arranged so as to be exposed from the valve sliding hole 5a when the needle valve 8 is initially lifted. Therefore,
When the initial lift is performed, the fuel is injected from the small recessed portion 16, whereby the initial injection is performed.

In the embodiment shown in FIG. 5, the depth of the notch 15 is gradually increased from the upper side to the lower side. In the case of this embodiment, the fuel injection direction changes downward. In addition, the embodiment shown in FIG.
It is a modification of the embodiment shown in FIG. 11, in which the depth of the notch 15 changes stepwise. This point is also applicable to the embodiment shown in FIGS. 1 to 3 or the embodiment shown in FIG.

In the embodiment shown in FIG. 7, a circular recess 17 as a notch is formed so as to communicate with the left side portion of the injection hole 8b. In this embodiment, FIG.
As shown in, the length of the injection hole 8b is short on the left side portion and long on the right side portion in the direction orthogonal to the lift direction of the needle valve 8. Therefore, when the fuel pressure exceeds the pressure P ₁ , the injected fuel spreads toward the left side in the circumferential direction of the needle valve 8. The recess 17 may be formed on the right side of the injection hole 8b. In that case, the fuel will spread to the right.

Further, as in the embodiment shown in FIG. 7, the fuel injection nozzle in which the fuel injection direction is changed to the left and right, that is, the circumferential direction of the nozzle 1, generates a swirl (swirl flow) in the combustion chamber. By combining with the internal combustion engine configured to perform the above, the fuel can be burned more efficiently.

That is, in the swirl type internal combustion engine, as shown in FIG. 8, a swirl flowing in the direction of the arrow is formed in the combustion chamber 20. When the fuel is injected from the conventional fuel injection nozzle N in this state and the swirl is weak, the spread of the fuel due to the swirl is small, and therefore the air in the combustion chamber 20 cannot be effectively used. On the contrary, when the swirl is excessively strong, a part of the fuel spread by the swirl overlaps with the fuel injected from the injection hole on the downstream side of the swirl, as shown by an imaginary line in FIG. The fuel concentration becomes too high in the overlapping portion.

When the spread of the fuel due to the swirl is small, as shown in FIG. 9, the fuel injection nozzle 1 whose fuel injection direction changes in the same direction as the swirl is used. With this configuration, the fuel that spreads in the same direction as the swirl is injected from the fuel injection nozzle 1, so that the fuel can be spread further downstream of the swirl. Therefore, the air in the combustion chamber 20 can be used more effectively.

Further, as shown by an imaginary line in FIG.
When the swirls are too strong and the fuels overlap with each other, as shown in FIG. 10, the fuel injection nozzle 1 in which the fuel injection direction changes in the opposite direction to the swirl is used. In this way, the fuel injected in the opposite direction to the swirl weakens the swirl. Therefore, it is possible to prevent the fuel injected from different injection holes from overlapping each other.

[0025]

As described above, according to the fuel injection nozzle of the present invention, the injection direction of the fuel can be changed during the injection, whereby the air in each part in the combustion chamber can be effectively utilized. It is possible to obtain the effect that the can be burned in a good state. In particular, according to the invention of claim 3, by combining with the swirl type internal combustion engine, it is possible to more effectively use the air in the combustion chamber.

[Brief description of drawings]

FIG. 1 shows an essential part of an embodiment of the present invention,
1A is a front sectional view thereof, and FIG. 1B is an enlarged sectional view taken along the line BB of FIG. 1A.

FIG. 2 is a cross-sectional view showing the overall configuration of the same embodiment.

FIG. 3 is a view for explaining the operation of the embodiment,
FIG. 3A is a diagram showing an injection state when the fuel pressure is below a predetermined pressure, and FIG. 3B is a diagram showing an injection state when the fuel pressure exceeds a predetermined pressure.

FIG. 4 is a sectional view similar to FIG. 1B showing a second embodiment of the present invention.

FIG. 5 is a sectional view similar to FIG. 1B showing a third embodiment of the present invention.

FIG. 6 is a sectional view similar to FIG. 1B showing a fourth embodiment of the present invention.

FIG. 7 is a view showing a fifth embodiment of the present invention, and FIG. 7 (A) is a front view showing the vicinity of the injection hole of the needle valve;
7B is an enlarged cross-sectional view taken along the line BB of FIG. 7A.

FIG. 8 is a diagram showing a situation when fuel is injected from a conventional fuel injection nozzle into a combustion chamber of a swirl type internal combustion engine.

FIG. 9 is a diagram showing a situation where fuel is injected from a fuel injection nozzle according to the present invention, which injects fuel in the same direction as a swirl into a combustion chamber of a swirl type internal combustion engine.

FIG. 10 is a diagram showing a situation when fuel is injected from a fuel injection nozzle according to the present invention, which injects fuel in a direction opposite to the swirl into a combustion chamber of a swirl type internal combustion engine.

[Explanation of symbols]

 1 Fuel Injection Nozzle 5 Nozzle Main Body 5a Valve Sliding Hole 5c Valve Seat 8 Needle Valve 8a Valve 8b Injection Hole 15 Notch 17 Recess (Notch)

Claims (3)

[Claims] 1. In a fuel injection nozzle for injecting fuel from an injection hole, a needle valve lifts from a valve seat to open when the pressure of fuel to be pumped reaches a predetermined valve opening pressure, and the injection hole is opened. By notching the outer surface of the injection hole, the length from the inner edge to the outer edge of the injection hole is made different between one side portion and the other side portion of the injection hole. nozzle. 2. The length from the inner edge to the outer edge of the injection hole is different between one side portion and the other side portion in the direction substantially along the lift direction of the needle valve. The fuel injection nozzle according to claim 1, wherein: 3. The length from the inner edge to the outer edge of the injection hole is different between one side portion and the other side portion in a direction substantially orthogonal to the lift direction of the needle valve. The fuel injection nozzle according to claim 1, wherein: