JP2001248524A - Fuel injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection nozzle capable of realizing a desired spray shape according to an operating condition of an engine, and purifying engine discharge gas. SOLUTION: Injection holes opened to an inner circumferential surface of a guide hole are formed on a nozzle body 2. The injection holes are composed of a first injection hole 7 positioned on a lower side in a lift direction of a needle 4 and a second injection hole 8 positioned on an upper side. When he injection hole length of the first injection hole 7 is set as L1, an injection hole diameter is set as D1, the injection hole length of the second injection hole 8 is set as L2, and an injection hole diameter is set as D2, the relation of the formula L1/D1<L2/D2 is satisfied. In the needle 4, only the first injection hole 7 is opened when fuel pressure in a vertical hole 9 is larger than first opening valve pressure. Both of first and second injection holes 7, 8 are opened when the fuel pressure in the vertical hole 9 is larger than second opening valve pressure.

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 high-pressure fuel into an internal combustion engine such as a diesel engine.

[0002]

2. Description of the Related Art In a direct injection engine, the shape and amount of fuel spray injected from a fuel injection nozzle into a combustion chamber of the engine are optimal depending on the operating state of the engine and the injection timing (early and late injections). is there. Conventional techniques for realizing this are disclosed in JP-A-62-103458 and JP-A-11-193766. The former is
By changing the number of injection nozzles in two stages according to the engine speed, an appropriate injection amount is realized. In the latter, the penetration force is improved by reducing the diameter of the injection hole and promoting atomization, by bringing the injection hole closer.

[0003]

However, in the former prior art, since the form of spray sprayed from the injection hole cannot be changed in accordance with the number of revolutions, if the design is made to give priority to the penetration force, the penetration force in the low-speed region will be reduced. Is too strong, the emission HC and smoke increase, and if the design is made with priority on the spray angle, there is a possibility that the penetration force is insufficient at a high speed range and the output is reduced. Also,
In the latter prior art, similarly to the former, there is a problem that the penetration force is too strong in a low-speed region, and further, there is a possibility that the ignition delay cannot be shortened due to insufficient atomization due to insufficient atomization. The present invention has been made based on the above circumstances, and an object of the present invention is to provide a fuel injection nozzle capable of achieving a desired spray shape according to an operating state of an engine and purifying engine exhaust gas.

[0004]

According to a first aspect of the present invention, the nozzle body has a first injection hole and a second injection hole which are opened on an inner peripheral surface of a guide hole with which the outer peripheral surface of the needle slides when the needle is lifted. A first injection hole is provided below the second injection hole in the lift direction of the needle, and only the first injection hole is opened when the needle is lifted in the first stage; A fuel injection nozzle configured to open both a first injection hole and a second injection hole when a stage lift is performed.
When the injection hole length of the injection hole is L1 and the injection hole diameter is D1, and the injection hole length of the second injection hole is L2 and the injection hole diameter is D2, the following expression is satisfied. L1 / D1 <L2 / D2 ............

According to this configuration, when the needle lifts to the first stage and only the first injection hole is opened, the L of the first injection hole is reduced.
Since 1 / D1 is smaller than L2 / D2 of the second injection hole, the contraction generated at the inlet of the first injection hole is continuously injected to the outlet of the injection hole. That is, the contracted flow generated at the inlet is less likely to re-adhere to the outlet of the injection hole, and is directly injected from the first injection hole. As a result, a spray having a wide spray angle is ejected, and mixing with air is promoted.
Combustion can be improved. When the needle lifts to the second stage to open both the first injection hole and the second injection hole, L2 / D2 of the second injection hole is larger than L1 / D1 of the first injection hole. After that, the contracted flow generated at the injection hole inlet portion adheres again to the injection hole outlet portion, and is rectified and injected. as a result,
A spray with a strong penetration force is injected, and the spray can be dispersed throughout the engine cylinder.

(2) The nozzle body has a first injection hole and a second injection hole which are opened on the inner peripheral surface of the guide hole with which the outer peripheral surface of the needle slides when the needle is lifted, The first injection hole is provided below the second injection hole in the lift direction of the needle, and only the first injection hole is opened when the needle is lifted at the first stage, and when the needle is lifted at the second stage. A fuel injection nozzle configured to open both a first injection hole and a second injection hole, wherein a chamfer R1 is applied to an entrance periphery of the first injection hole, and an entrance of the second injection hole is formed. When the chamfer R2 is provided on the periphery, the chamfer R2 of the second injection hole is larger than the chamfer R1 of the first injection hole.

According to this structure, the chamfer R of the second injection hole is provided.
By setting 2 large, even if the injection hole length is short, fuel can flow smoothly into the second injection hole.
In this case, since the contraction is not generated in the second injection hole and the injection is performed in a rectified state, the spray having a strong penetration force is injected. Therefore, even if the spray angle is prioritized, it is possible to inject a spray having a strong penetration force in a high speed range.

(3) The nozzle body has a first injection hole and a second injection hole which are opened on the inner peripheral surface of the guide hole with which the outer peripheral surface of the needle slides when the needle is lifted, The first injection hole is provided below the second injection hole in the lift direction of the needle, and only the first injection hole is opened when the needle is lifted at the first stage, and when the needle is lifted at the second stage. A fuel injection nozzle configured to open both a first injection hole and a second injection hole, wherein the first injection hole is provided such that the diameter of the injection hole gradually increases from an inlet to an outlet. Have been. According to this configuration, even if the injection hole length is set to be large, it is difficult for the contraction flow generated at the injection hole entrance to be reattached in the first injection hole. Further, since the fuel injected from the first injection hole expands in the outer diameter direction from the inlet to the outlet in the first injection hole, injection with a large spray angle is possible. Therefore, it is possible to spray a spray having a wide spray angle in a low speed range even if the design is made to give priority to the penetration force.

(4) The nozzle body has a first injection hole and a second injection hole which are opened on the inner peripheral surface of the guide hole with which the outer peripheral surface of the needle slides when the needle is lifted, The first injection hole is provided below the second injection hole in the lift direction of the needle, and only the first injection hole is opened when the needle is lifted at the first stage, and when the needle is lifted at the second stage. A fuel injection nozzle configured to open both a first injection hole and a second injection hole, wherein the second injection hole is provided such that the diameter of the injection hole gradually decreases from an inlet to an outlet. Have been. According to this configuration, the contracted flow generated at the inlet of the second injection hole is easily re-adhered in the second injection hole, and is rectified. Further, the fuel injected from the second injection hole is
In the nozzle hole, the diameter decreases in the inner diameter direction from the inlet to the outlet, so that the injection with a strong penetration force is possible. Therefore, even if the spray angle is prioritized, it is possible to inject a spray having a strong penetration force in a high speed range.

(5) The nozzle body has a first injection hole and a second injection hole which are opened on the inner peripheral surface of the guide hole with which the outer peripheral surface of the needle slides when the needle is lifted, The first injection hole is provided below the second injection hole in the lift direction of the needle, and only the first injection hole is opened when the needle is lifted at the first stage, and when the needle is lifted at the second stage. A fuel injection nozzle configured to open both a first injection hole and a second injection hole, wherein the first injection hole has an injection hole central axis passing through a center of an inlet and a center of an outlet. The second injection hole is provided eccentrically with respect to the nozzle center axis, and the injection hole center axis passing through the center of the inlet and the center of the outlet crosses the nozzle center axis.

According to this configuration, since the first injection hole is provided eccentrically with respect to the center axis of the nozzle, the flow direction of the fuel flowing into the first injection hole is particularly large on both sides of the injection hole inlet. In contrast, a large contraction occurs on one side of the first injection hole. For this reason, even when the injection hole length is large, the injection is performed without re-adhering in the first injection hole, so that a spray having a wide spray angle can be sprayed. Further, since the second injection hole is provided so as to intersect the central axis of the nozzle, a large contraction does not occur, and a spray having a strong penetration force can be ejected from the second injection hole.

(Claim 6) When the needle is lifted in the first stage, the gap between the sheet portion and the sheet surface becomes the minimum flow path area.
A fuel injection nozzle configured such that the total inlet opening area of the nozzle hole and the second nozzle hole is a minimum flow passage area, wherein the nozzle hole length of the first nozzle hole is L1 and the nozzle hole diameter is D1. When the injection hole length of the second injection hole is L2 and the injection hole diameter is D2, the following relationship is satisfied: L1 / D1 <L2 / D2.

[0013] The fuel injection nozzle of the present invention has one needle.
When the stage is lifted, a narrowed portion is formed in which a gap between the sheet portion and the sheet surface has a minimum flow passage area. In this case, the fuel pressure is higher at the inlet of the first injection hole that opens upstream from the inlet of the second injection hole on the downstream side of the throttle portion. Is done. In this case, since the ratio L1 / D1 of the first injection hole is smaller than the ratio L2 / D2 of the second injection hole, the contraction generated at the inlet of the first injection hole is continuously injected to the outlet of the injection hole. Is done. That is, the contracted flow generated at the inlet portion is less likely to re-adhere to the injection hole outlet portion,
It is injected from the first injection hole as it is. Thereby, a spray having a wide spray angle is injected, and mixing with air is promoted, so that combustion can be improved.

When the needle is lifted to the second stage, the total inlet opening area of the first injection hole and the second injection hole becomes the minimum flow passage area. Equally second
The pressure at the inlet of the nozzle hole also increases. As a result, the fuel is injected from both the first injection hole and the second injection hole. In this case, since L2 / D2 of the second injection hole is larger than L1 / D1 of the first injection hole, the contraction generated at the injection hole entrance portion is reattached to the injection hole exit portion and rectified. And is injected. As a result, a spray having a strong penetration force is injected, and the spray can be dispersed throughout the engine cylinder.

(Means of Claim 7) When the needle is lifted in the first step, the gap between the sheet portion and the sheet surface becomes the minimum flow path area.
A fuel injection nozzle configured such that the total inlet opening area of the injection hole of the first injection hole and the second injection hole becomes the minimum flow path area, wherein the inlet edge of the first injection hole is chamfered R1, When the chamfer R2 is formed on the periphery of the entrance of the nozzle hole, the chamfer R2 of the second nozzle hole is larger than the chamfer R1 of the first nozzle hole. In the fuel injection nozzle of the present invention, when the needle is lifted at the first stage, the gap between the seat portion and the seat surface forms a throttle portion having a minimum flow passage area. in this case,
On the downstream side of the throttle section, the fuel pressure is higher at the inlet of the first injection hole, which is opened more upstream than the inlet of the second injection hole, so that the fuel is mainly injected from the first injection hole.

Further, when the needle is lifted to the second stage, the total inlet opening area of the first injection hole and the second injection hole becomes the minimum flow passage area. Equally second
The pressure at the inlet of the nozzle hole also increases. As a result, the fuel is injected from both the first injection hole and the second injection hole. According to this configuration,
By making the chamfer R2 of the second injection hole large, fuel can smoothly flow into the second injection hole even when the injection hole length is short. As a result, no contraction occurs in the second injection hole, and the jet is injected in a rectified state.
A spray with strong penetration is sprayed. Therefore, even if the spray angle is prioritized, it is possible to inject a spray having a strong penetration force in a high speed range.

(8) When the needle is lifted in the first stage, the gap between the sheet portion and the sheet surface becomes the minimum flow path area, and when the needle is lifted in the second stage, the first passage is lifted.
A fuel injection nozzle configured such that the total inlet opening area of the injection hole and the second injection hole is a minimum flow passage area, wherein the diameter of the injection hole of the first injection hole gradually increases from the inlet to the outlet. It is provided to be large. In the fuel injection nozzle of the present invention, when the needle is lifted at the first stage, the gap between the seat portion and the seat surface forms a throttle portion having a minimum flow passage area. In this case, the fuel pressure is higher at the inlet of the first injection hole that opens upstream from the inlet of the second injection hole on the downstream side of the throttle portion. Is done.

When the needle is lifted to the second stage, the total inlet opening area of the first injection hole and the second injection hole becomes the minimum flow passage area. Equally second
The pressure at the inlet of the nozzle hole also increases. As a result, the fuel is injected from both the first injection hole and the second injection hole. According to this configuration,
Even if the injection hole length of the first injection hole is set to be large, it is difficult for the contraction flow generated at the injection hole entrance to adhere again in the first injection hole.
Further, since the fuel injected from the first injection hole expands in the outer diameter direction from the inlet to the outlet in the first injection hole, injection with a large spray angle is possible. Therefore, it is possible to spray a spray having a wide spray angle in a low speed range even if the design is made to give priority to the penetration force.

(Claim 9) When the needle is lifted in the first stage, the gap between the sheet portion and the sheet surface becomes the minimum flow passage area.
A fuel injection nozzle configured such that the total inlet opening area of the nozzle hole and the second nozzle hole is the minimum flow passage area, and the diameter of the nozzle hole of the second nozzle hole gradually increases from the inlet to the outlet. It is provided to be small. In the fuel injection nozzle of the present invention, when the needle is lifted at the first stage, the gap between the seat portion and the seat surface forms a throttle portion having a minimum flow passage area. In this case, the fuel pressure is higher at the inlet of the first injection hole that opens upstream from the inlet of the second injection hole on the downstream side of the throttle portion. Is done.

When the needle is lifted to the second stage, the total inlet opening area of the first injection hole and the second injection hole becomes the minimum flow passage area. Equally second
The pressure at the inlet of the nozzle hole also increases. As a result, the fuel is injected from both the first injection hole and the second injection hole. According to this configuration,
The contraction generated at the inlet of the second injection hole is easily re-adhered in the second injection hole and is rectified. Further, since the fuel injected from the second injection hole narrows in the inner diameter direction from the inlet to the outlet in the second injection hole, injection with a strong penetration force is possible. Therefore, even if the spray angle is prioritized, it is possible to inject a spray having a strong penetration force in a high speed range.

According to a tenth aspect of the present invention, when the needle is lifted in the first stage, the gap between the sheet portion and the sheet surface has a minimum flow passage area. When the needle is lifted in the second stage, the first injection hole is formed. And a fuel injection nozzle configured such that the total inlet opening area of the second injection hole is a minimum flow path area.
The nozzle hole is provided such that the central axis of the nozzle hole passing through the center of the inlet and the center of the outlet is eccentric with respect to the central axis of the nozzle, and the second nozzle hole defines the center of the inlet and the center of the outlet. The central axis of the orifice that passes
It is provided to cross the nozzle center axis. In the fuel injection nozzle of the present invention, when the needle is lifted at the first stage, the gap between the seat portion and the seat surface forms a throttle portion having a minimum flow passage area. In this case, on the downstream side of the throttle section, the second
Since the fuel pressure is higher at the inlet of the first injection hole, which is open on the upstream side than the inlet of the injection hole, the fuel is mainly injected from the first injection hole.

Further, when the needle is lifted to the second stage, the total inlet opening area of the first injection hole and the second injection hole becomes the minimum flow passage area. Equally second
The pressure at the inlet of the nozzle hole also increases. As a result, the fuel is injected from both the first injection hole and the second injection hole. According to this configuration,
Since the first injection hole is provided eccentrically with respect to the center axis of the nozzle, the flow direction of the fuel flowing into the first injection hole is greatly different particularly on both sides of the injection hole entrance, and one side of the first injection hole is provided. Causes a large contraction. For this reason, even when the injection hole length is large,
Since the fuel is injected without re-adhering in the first injection hole, a spray having a wide spray angle can be sprayed. Further, since the second injection hole is provided so as to intersect the central axis of the nozzle, a large contraction does not occur, and a spray having a strong penetration force can be ejected from the second injection hole.

[0023]

Next, an embodiment of the present invention will be described with reference to the drawings. (First Embodiment) FIG. 1 is a cross-sectional view of a nozzle tip at a low lift, FIG. 2 is a cross-sectional view of a nozzle tip at a high lift, and FIG. 3 is an overall cross-sectional view of a fuel injection nozzle. The fuel injection nozzle 1 according to the present embodiment injects high-pressure fuel into a cylinder of a diesel engine, and includes a nozzle body 2, a seat member 3, and a needle 4, as shown in FIG. It is mounted on a nozzle holder (not shown) for setting the pressure (first valve opening pressure and second valve opening pressure).

The nozzle body 2 has a guide hole 5 into which the needle 4 is slidably inserted, a fuel passage 6 communicating with the guide hole 5, and an injection hole (a first hole) for injecting high-pressure fuel into the engine cylinder. The first injection hole 7 and the second injection hole 8) are formed. The guide hole 5 has its upper end opened at the upper end surface of the nozzle body 2 and its lower end closed without penetrating the bottom of the nozzle body 2. The injection holes 7 and 8 are composed of a first injection hole 7 located on the lower side in the lift direction of the needle 4 (the vertical direction in FIG. 3) and a second injection hole 8 located on the upper side. From the inner peripheral surface of the nozzle body 2 to the outer peripheral surface of the nozzle body 2 in a substantially radial direction through the annular wall portion 2a of the nozzle body 2.
A plurality of the first injection holes 7 and the second injection holes 8 are respectively provided in the circumferential direction.

Here, as shown in FIG. 1, the nozzle body 2 has an injection hole length L1 and an injection hole diameter D1 of the first injection hole 7 and an injection hole length L2 and an injection hole diameter of the second injection hole 8 as shown in FIG. When the diameter of the injection hole is D2, the following relationship is established between the first injection hole 7 and the second injection hole 8. L1 / D1 <L2 / D2 In particular, in this embodiment, in order to shorten the injection hole length L1 of the first injection hole 7, the annular wall of the nozzle body 2 through which the first injection hole 7 penetrates. The thickness of the portion 2a is reduced.

The sheet member 3 is inserted into the guide hole 5 with a small clearance, and is housed at the bottom of the guide hole 5. The seat member 3 has a truncated cone-shaped seat surface 3a formed on an upper side thereof, and an outer diameter end 3b of the seat surface 3a.
Is provided at a position lower than the lower end 7a of the entrance opening edge of the first injection hole 7 (see FIG. 1). Needle 4
Is slidably fitted into the guide hole 5 with a clearance of several μm, and is provided so as to be lifted in two stages by a nozzle holder. In the following description, the first-stage needle lift is referred to as a low lift, and the second-stage needle lift is referred to as a high lift.

As shown in FIG. 3, the needle 4 has
A fuel passage including a vertical hole 9, a fuel reservoir 10, and a horizontal hole 11 is formed. The vertical hole 9 is formed to extend in the longitudinal direction at the center of the needle 4, the lower end is opened at the lower end surface of the needle 4, and the upper end is closed. The fuel reservoir 10 is formed in an annular shape around the vertical hole 9 above the needle 4 and communicates with the fuel conduit 6 of the nozzle body 2. The lateral hole 11 is
The vertical hole 9 penetrates in the radial direction to communicate the vertical hole 9 with the fuel reservoir 10. On the lower end surface of the needle 4, an inner conical surface 4a and an outer conical surface 4b which are tapered from the periphery of the opening of the vertical hole 9 are formed, and an intersection (ridge) of the inner conical surface 4a and the outer conical surface 4b is formed. The protruding portion constitutes the seat portion 4c.

When the fuel pressure in the vertical hole 9 is smaller than the first valve opening pressure, the needle 4
a. At this time, the outer peripheral edge of the outer conical surface 4b (the outer peripheral edge 4d of the needle 4) is located below the lower end 7a of the entrance opening edge of the first injection hole 7, and the outer peripheral surface of the needle 4 is in the first injection position. The entrance opening surfaces of the hole 7 and the second injection hole 8 are closed. When the fuel pressure in the vertical hole 9 becomes larger than the first valve opening pressure, the outer peripheral edge 4d of the needle 4 is lifted by the maximum lift amount HD1 at the time of low lift shown in FIG.
And the second nozzle hole 8 is moved to open only the first nozzle hole 7. Further, when the fuel pressure in the vertical hole 9 becomes larger than the second valve opening pressure, the outer peripheral edge 4d of the needle 4 is lifted by the maximum lift amount HD2 at the time of high lift shown in FIG. It moves upward to open both the first injection hole 7 and the second injection hole 8.

Next, the operation and effect of the fuel injection nozzle 1 will be described. When high-pressure fuel pressure-fed from a fuel injection pump (not shown) is supplied to the vertical hole 9 in the needle 4 via the fuel conduit 6 and the fuel pressure becomes higher than the first valve opening pressure,
When the needle 4 is pushed up, the maximum lift amount shown in FIG.
Lift only HD1. Accordingly, only the first injection hole 7 is opened, and the high-pressure fuel supplied into the needle 4 is injected from the first injection hole 7 into the engine cylinder.

At this time, since only the first injection hole 7 is open, the injection hole area is smaller than the whole (the total opening area of the first injection hole 7 and the second injection hole 8). For this reason, since high-pressure fuel is injected with a small injection hole diameter, atomization of spray is promoted. Further, since L1 / D1 of the first injection hole 7 is smaller than L2 / D2 of the second injection hole 8, the contraction generated at the inlet of the first injection hole 7 continues to the outlet of the injection hole. Is injected.
In other words, the contracted flow generated at the entrance of the first injection hole 7 is less likely to re-adhere to the exit of the injection hole, and is injected from the first injection hole 7 as it is. Thereby, a spray having a wide spray angle is injected, and mixing with air is promoted, so that combustion can be improved.

Further, the fuel pressure in the vertical hole 9 increases and the second
When the pressure becomes larger than the valve opening pressure, the needle 4 is further pushed up and lifted by the maximum lift amount HD2 shown in FIG. Thereby, both the first injection hole 7 and the second injection hole 8 are opened, and the high-pressure fuel supplied into the needle 4 is supplied to the first injection hole 7.
And the second injection hole 8 is injected into the engine cylinder. At this time, since the injection hole area becomes larger than at the time of low lift, an appropriate injection rate can be realized. Also, since L2 / D2 of the second injection hole 8 is larger than L1 / D1 of the first injection hole 7, the contraction generated at the injection hole entrance of the second injection hole 8 reaches the injection hole exit. Redistributes between and is rectified and injected.
As a result, a spray having a strong penetration force is injected, and the spray can be dispersed in the engine cylinder, so that combustion can be improved. Thereafter, when the fuel pressure in the vertical hole 9 becomes smaller than the first valve opening pressure, the needle 4 descends, the seat portion 4c sits on the seat surface 3a, and the outer peripheral surface of the needle 4 is in the first injection hole 7 and The fuel injection is terminated by closing the entrance opening surface of the second injection hole 8.

(Second Embodiment) FIGS. 4A and 4B are a sectional view of the nozzle tip at the time of low lift and a sectional view of the nozzle tip at the time of high lift. FIG. 4 shows a fuel injection nozzle according to this embodiment.
As shown in the figure, the nozzle body 2 through which the first injection hole 7 penetrates
The counterbore hole 12 is formed in the annular wall portion 2a of
This is an example in which the injection hole length L1 of the injection hole 7 is shortened. The counterbore 12 has a diameter larger than the diameter D1 of the first injection hole 7 and is formed concentrically with the first injection hole 7 and downstream of the first injection hole 7. Depending on the depth of the counterbore 12, a desired injection hole length L1 can be realized. Thereby, the same effect as in the first embodiment can be obtained.

(Third Embodiment) FIGS. 5A and 5B are a sectional view of the nozzle tip at the time of low lift and a sectional view of the nozzle tip at the time of high lift. The fuel injection nozzle according to the present embodiment is an example in which a chamfer is provided at an injection hole inlet portion and a spray shape is changed according to the size of the chamfer. In this embodiment, as shown in FIG. 5, when the chamfer R1 is formed at the entrance periphery of the first injection hole 7 and the chamfer R2 is formed at the entrance periphery of the second injection hole 8, the first The chamfer R2 of the second injection hole 8 is larger than the chamfer R1 of the injection hole 7. According to this configuration, by making the chamfer R2 of the second injection hole 8 large, fuel can flow into the second injection hole 8 smoothly even when the injection hole length is short. In this case, the second
The nozzles are jetted in a rectified state without causing contraction in the injection holes 8 of the nozzles, so that a spray having a strong penetration force is jetted. Therefore, even if the spray angle is prioritized, it is possible to inject a spray having a strong penetration force in a high speed range.

(Fourth Embodiment) FIGS. 6A and 6B are a sectional view of the nozzle tip at the time of low lift and a sectional view of the nozzle tip at the time of high lift, respectively. The fuel injection nozzle of the present embodiment is shown in FIG.
This is an example in which the injection hole diameter is changed from the inlet to the outlet as shown in FIG. The first nozzle hole 7 is provided such that the nozzle hole diameter D1o at the outlet is larger than the nozzle hole diameter D1i at the inlet, and the nozzle hole diameter gradually increases from the inlet to the outlet.
The nozzle hole 8 is provided such that the nozzle hole diameter D2o at the outlet is smaller than the nozzle hole diameter D2i at the inlet, and the nozzle hole diameter gradually decreases from the inlet toward the outlet.

According to this configuration, as shown in FIG. 6A, even if the injection hole length L1 of the first injection hole 7 is set to be as large as the injection hole length of the second injection hole 8. In addition, the contracted flow generated at the inlet of the injection hole is less likely to adhere again in the first injection hole 7. Also, the first
Since the fuel injected from the nozzle hole 7 of the first nozzle hole 7 spreads in the outer diameter direction from the inlet to the outlet in the first nozzle hole 7, the injection with a large spray angle is possible. Therefore, even if the design is made to give priority to the penetration force, it is possible to spray a spray having a wide spray angle in a low speed range. In the second injection hole 8, as shown in FIG. 6B, the contraction flow generated at the inlet easily adheres again in the second injection hole 8 and is rectified and injected. Further, the second injection hole 8
Since the fuel injected from the inside of the second injection hole 8 narrows in the radial direction from the inlet to the outlet in the second injection hole 8, injection with a strong penetration force is possible. Therefore, even if the spray angle is prioritized, it is possible to jet a spray having a strong penetration force in a high-speed range.

(Fifth Embodiment) FIGS. 7A and 7B are a sectional view of the tip of the nozzle at the time of high lift and a sectional view in the radial direction of the nozzle body 2. The fuel injection nozzle of the present embodiment is shown in FIG.
This is an example in which the first injection hole 7 is provided eccentrically with respect to the nozzle center axis O as shown in FIG. The first injection hole 7 is provided such that an injection hole center axis A passing through the center of the inlet and the center of the outlet is eccentric with respect to the nozzle center axis O, and the second injection hole 8 is
An injection hole center axis B passing through the center of the inlet and the center of the outlet is provided to cross the center axis of the nozzle.

According to this configuration, as shown in FIG. 7 (b), the flow direction of the fuel flowing into the first injection hole 7 is greatly different, especially on both sides in the circumferential direction of the injection hole inlet. 7 has a large contraction on one side. For this reason, even when the injection hole length L1 is large, the injection is performed without re-adhering in the first injection hole 7, so that a spray having a wide spray angle can be sprayed. Further, since the second injection hole 8 is provided to intersect with the nozzle center axis O, a large contraction does not occur, and a spray having a strong penetration force can be injected. Note that the two-dot chain line in FIG.
The position of the needle 4 during a low lift is shown.

(Sixth Embodiment) FIGS. 8A and 8B are a sectional view of the nozzle tip at a low lift and a sectional view of the nozzle tip at a high lift. The fuel injection nozzle of the present embodiment has a fuel passage 21 formed in a nozzle body 20, a conical seat surface 22 downstream of the fuel passage 21, and a first injection hole 23 and a second injection hole 23 formed in the seat surface 22. Two injection holes 24 are open. The first injection hole 23 is opened on the upstream side of the second injection hole 24 in the fuel flow direction on the seat surface 22.

The first injection hole 23 and the second injection hole 24
As in the above-described fourth embodiment, the diameter of each injection hole changes from the inlet to the outlet. The first injection hole 23 is provided such that the diameter of the injection hole at the outlet is larger than the diameter of the injection hole at the inlet, and the diameter of the injection hole gradually increases from the inlet to the outlet. The diameter of the injection hole at the outlet is smaller than the diameter of the injection hole, and the diameter of the injection hole is gradually reduced from the inlet to the outlet.

The needle 25 is slidably fitted into the nozzle body 20 and is provided so as to be liftable in two stages, and has a seat 26 at its lower end. This needle 2
5, when the fuel pressure is lower than the first valve opening pressure, the seat portion 26 sits on the seat surface 22 upstream of the first injection hole 23 to shut off the fuel passage 21. When the fuel pressure becomes larger than the first valve opening pressure, the lift is performed by the maximum lift amount at the time of the low lift shown in FIG. At this time, the annular gap formed between the sheet portion 26 and the sheet surface 22 becomes the minimum flow path area. When the fuel pressure becomes larger than the second valve opening pressure, FIG.
Lift by the maximum lift amount at the time of high lift shown in (b). At this time, the total inlet opening area of the first injection hole 23 and the second injection hole 24 becomes the minimum flow passage area.

FIG. 9 shows the results of simulation analysis of the pressure distribution in the nozzle during low lift and during high lift. According to this analysis result, the flow path area is most narrowed in the seat portion of the needle at the time of the low lift, and therefore, as shown in FIG. The pressure gradually decreases from the sheet portion toward the inlet of the injection hole, and further decreases in the injection hole. In addition, at the time of a high lift, the inlet of the injection hole has the minimum flow path area, and therefore, as shown in FIG. I have.

As can be seen from the above analysis results, at the time of a low lift, the first opening opening upstream of the second injection hole 24 is provided.
Since the inlet pressure of the nozzle hole 23 is higher, the fuel is mainly injected from the first nozzle hole 23. In this case, the first injection hole 23
Is provided such that the diameter of the injection hole gradually increases from the inlet to the outlet, so that the injection hole length of the first injection hole 23 is set to be equal to the injection hole length of the second injection hole 24. Also, it becomes difficult for the contraction flow generated at the injection hole inlet to adhere again in the injection hole. Further, the fuel injected from the first injection hole 23 is supplied to the first injection hole 2.
Because it expands in the outer diameter direction from the entrance to the exit in 3,
Injection with a large spray angle is possible. Therefore, even if the design is made to prioritize the penetration force, it is possible to inject a spray having a wide spray angle in a low-speed range, thereby improving combustion.

At the time of high lift, the total inlet opening area of the first injection hole 23 and the second injection hole 24 becomes the minimum flow passage area. Nozzle 2
The inlet pressure of 4 also increases. As a result, the fuel is injected from both the first injection hole 23 and the second injection hole 24. In this case, the second
The nozzle hole 24 is provided so that the diameter of the nozzle hole gradually decreases from the inlet to the outlet, so that the contraction flow generated at the inlet of the nozzle hole is easily reattached in the nozzle hole, and is rectified and injected. Is done. Furthermore, since the fuel injected from the second injection hole 24 narrows in the inner diameter direction from the inlet to the outlet in the second injection hole 24, injection with a strong penetration force is possible. Therefore,
Even if the spray angle is prioritized, a spray with a strong penetration force can be injected in a high-speed range, and combustion can be improved.

(Modification) In the sixth embodiment, similarly to the above-described fourth embodiment, the first injection holes 23 and the second injection holes 24 are provided.
Although the diameter of each injection hole is changed, the first injection hole 23
With respect to the relationship between
The configurations described in the second, third, and fifth embodiments may be applied. The fuel injection nozzle according to the present invention has a nozzle body 2, 20
And the needles 4 and 25, and the structure of the nozzle holder is not limited. For example, the present invention can be applied to an injector capable of arbitrarily varying a needle lift amount by driving a piezo element, or an injector capable of gradually varying a needle lift amount by driving an electromagnetic valve.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a nozzle tip at a low lift (first embodiment).

FIG. 2 is a cross-sectional view of a nozzle tip portion during a high lift (first embodiment).

FIG. 3 is an overall sectional view of a fuel injection nozzle. (First embodiment).

FIG. 4A is a cross-sectional view of the nozzle tip at the time of low lift and FIG. 4B is a cross-sectional view of the nozzle tip at the time of high lift (second embodiment).

FIG. 5A is a cross-sectional view of the nozzle tip at the time of low lift and FIG. 5B is a cross-sectional view of the nozzle tip at the time of high lift (third embodiment).

FIG. 6A is a cross-sectional view of the nozzle tip at the time of low lift and FIG. 6B is a cross-sectional view of the nozzle tip at the time of high lift (fourth embodiment).

FIG. 7A is a cross-sectional view of a nozzle tip portion at the time of a high lift, and FIG. 7B is a radial cross-sectional view of a nozzle body (fifth embodiment).

FIG. 8A is a cross-sectional view of the nozzle tip at the time of low lift and FIG. 8B is a cross-sectional view of the nozzle tip at the time of high lift (Sixth Embodiment).

FIG. 9 is a pressure distribution diagram in a nozzle (sixth embodiment).

[Explanation of symbols]

 (First to fifth embodiments) 1 fuel injection nozzle 2 nozzle body 4 needle 5 guide hole 7 first injection hole 8 second injection hole (sixth embodiment) 20 nozzle body 21 fuel passage 22 seat surface 23 first Injection hole 24 second injection hole 25 needle 26 seat part

Claims (10)

[Claims] 1. A nozzle body having a guide hole formed at a central portion thereof, and a needle slidably fitted into the guide hole and provided in two stages so as to be liftable. A first injection hole and a second injection hole which are opened on an inner peripheral surface of the guide hole with which an outer peripheral surface of the needle slides when the needle is lifted, and wherein the first injection hole is provided in a lift direction of the needle; Is provided below the second injection hole, only the first injection hole is opened when the needle is lifted in the first stage, and the first injection hole is opened when the needle is lifted in the second stage. And a second injection hole, wherein the first injection hole has an injection hole length L1 and an injection hole diameter D1, and the second injection hole has an injection hole. When the hole length is L2 and the injection hole diameter is D2, L1 / D1 <L2 / D2... A fuel injection nozzle that satisfies the above relationship. 2. A nozzle body having a guide hole formed in a central portion, and a needle slidably fitted in the guide hole and provided in two stages so as to be liftable, wherein the nozzle body is A first injection hole and a second injection hole which are opened on an inner peripheral surface of the guide hole with which an outer peripheral surface of the needle slides when the needle is lifted, and wherein the first injection hole is provided in a lift direction of the needle; Is provided below the second injection hole, only the first injection hole is opened when the needle is lifted in the first stage, and the first injection hole is opened when the needle is lifted in the second stage. A fuel injection nozzle configured such that both the first and second injection holes are opened, wherein a chamfer R1 is applied to an entrance periphery of the first injection hole, and a chamfer is provided to an entrance periphery of the second injection hole. When R2 is applied, the chamfer R1 of the first injection hole Serial second fuel injection nozzles, characterized in that the larger chamfer R2 of the injection hole. 3. A nozzle body having a guide hole formed in a central portion thereof, and a needle slidably fitted into the guide hole and provided so as to be liftable in two stages. A first injection hole and a second injection hole which are opened on an inner peripheral surface of the guide hole with which an outer peripheral surface of the needle slides when the needle is lifted, and wherein the first injection hole is provided in a lift direction of the needle; Is provided below the second injection hole, only the first injection hole is opened when the needle is lifted in the first stage, and the first injection hole is opened when the needle is lifted in the second stage. A fuel injection nozzle configured to open both the first and second injection holes, wherein the first injection hole is provided such that the diameter of the injection hole gradually increases from an inlet to an outlet. A fuel injection nozzle. 4. A nozzle body having a guide hole formed at a central portion thereof, and a needle slidably fitted into the guide hole and provided in two stages so as to be liftable. A first injection hole and a second injection hole which are opened on an inner peripheral surface of the guide hole with which an outer peripheral surface of the needle slides when the needle is lifted, and wherein the first injection hole is provided in a lift direction of the needle; Is provided below the second injection hole, only the first injection hole is opened when the needle is lifted in the first stage, and the first injection hole is opened when the needle is lifted in the second stage. And a fuel injection nozzle configured to open both the second injection hole and the second injection hole, wherein the second injection hole is provided such that the diameter of the injection hole gradually decreases from the inlet to the outlet. A fuel injection nozzle. 5. A nozzle body having a guide hole formed at a central portion thereof, and a needle slidably fitted into the guide hole and provided in two stages so as to be liftable. A first injection hole and a second injection hole which are opened on an inner peripheral surface of the guide hole with which an outer peripheral surface of the needle slides when the needle is lifted, and wherein the first injection hole is provided in a lift direction of the needle; Is provided below the second injection hole, only the first injection hole is opened when the needle is lifted in the first stage, and the first injection hole is opened when the needle is lifted in the second stage. A fuel injection nozzle configured such that both the first and second injection holes are open, wherein the first injection hole has a nozzle center axis passing through a center of an inlet and a center of an outlet. The second injection hole is provided eccentrically with respect to the center of the inlet. A fuel injection nozzle, wherein a central axis of the injection hole passing through the center of the mouth is provided to cross the central axis of the nozzle. 6. A fuel passage for supplying high-pressure fuel, a seat surface downstream of the fuel passage, and a first injection hole and a second injection hole opened in the seat surface. A nozzle body having the first injection hole opening upstream of the second injection hole in the fuel flow direction; a nozzle body slidably fitted into the nozzle body and provided so as to be liftable in two stages; A needle having a seat portion at a lower end thereof, the seat portion being seated on the seat surface upstream of the first injection hole to shut off the fuel passage; and the needle lifted at a first stage. Sometimes, the gap between the sheet portion and the sheet surface becomes the minimum flow path area, and when the needle is lifted to the second stage, the total inlet opening area of the first injection hole and the second injection hole becomes the minimum flow area. A fuel injection nozzle configured to have a road area, wherein the first injection hole When the hole length is L1 and the injection hole diameter is D1, and the injection hole length of the second injection hole is L2 and the injection hole diameter is D2, the following relationship is satisfied: L1 / D1 <L2 / D2. A fuel injection nozzle. 7. A fuel passage for supplying high-pressure fuel, a seat surface downstream of the fuel passage, and a first injection hole and a second injection hole opened on the seat surface. A nozzle body having the first injection hole opening upstream of the second injection hole in the fuel flow direction; a nozzle body slidably fitted into the nozzle body and provided so as to be liftable in two stages; A needle having a seat portion at a lower end thereof, the seat portion being seated on the seat surface upstream of the first injection hole to shut off the fuel passage; and the needle lifted at a first stage. Sometimes, the gap between the sheet portion and the sheet surface becomes the minimum flow path area, and when the needle is lifted to the second stage, the total inlet opening area of the first injection hole and the second injection hole becomes the minimum flow area. A fuel injection nozzle configured to have a road area, wherein the first injection hole When the chamfer R1 is applied to the peripheral edge of the mouth and the chamfer R2 is applied to the peripheral edge of the entrance of the second injection hole, the chamfer R2 of the second injection hole is larger than the chamfer R1 of the first injection hole. A fuel injection nozzle characterized by being large. 8. A fuel passage for supplying high-pressure fuel, a seat surface downstream of the fuel passage, and a first injection hole and a second injection hole opened in the seat surface. A nozzle body having the first injection hole opening upstream of the second injection hole in the fuel flow direction; a nozzle body slidably fitted into the nozzle body and provided so as to be liftable in two stages; A needle having a seat portion at a lower end thereof, the seat portion being seated on the seat surface upstream of the first injection hole to shut off the fuel passage; and the needle lifted at a first stage. Sometimes, the gap between the sheet portion and the sheet surface becomes the minimum flow path area, and when the needle is lifted to the second stage, the total inlet opening area of the first injection hole and the second injection hole becomes the minimum flow area. A fuel injection nozzle configured to have a road area, wherein the first injection hole is A fuel injection nozzle, characterized in that the nozzle hole diameter from the inlet toward the outlet is provided so as gradually increases. 9. A fuel supply passage for supplying high-pressure fuel, a seat surface downstream of the fuel passage, a first injection hole and a second injection hole opened to the seat surface, A nozzle body having the first injection hole opening upstream of the second injection hole in the fuel flow direction; a nozzle body slidably fitted into the nozzle body and provided so as to be liftable in two stages; A needle having a seat portion at a lower end thereof, the seat portion being seated on the seat surface upstream of the first injection hole to shut off the fuel passage; and the needle lifted at a first stage. Sometimes, the gap between the sheet portion and the sheet surface becomes the minimum flow path area, and when the needle is lifted to the second stage, the total inlet opening area of the first injection hole and the second injection hole becomes the minimum flow area. A fuel injection nozzle configured to have a road area, wherein the second injection hole is A fuel injection nozzle, characterized in that the nozzle hole diameter from the inlet toward the outlet is provided so as gradually decreases. 10. A fuel supply system having a fuel passage through which high-pressure fuel is supplied,
A seat surface is provided downstream of the fuel passage, and a first injection hole and a second injection hole that are open to the seat surface are provided, and the first injection hole is a second injection hole in a fuel flow direction. A nozzle body that is open more upstream, is slidably fitted into the nozzle body, is provided so as to be liftable in two stages, has a seat portion at its lower end, and is upstream from the first injection hole. A needle that seats the seat portion on the seat surface and shuts off the fuel passage on the side. When the needle is lifted at the first stage, the gap between the seat portion and the seat surface has a minimum flow area. A fuel injection nozzle configured such that when the needle is lifted to the second stage, the total inlet opening area of the first injection hole and the second injection hole becomes a minimum flow path area, The first injection hole has an injection hole center axis passing through the center of the inlet and the center of the outlet, and The second injection hole is provided such that the injection hole central axis passing through the center of the inlet and the center of the outlet intersects with the central axis of the nozzle. Characteristic fuel injection nozzle.