JP2001200774A - Variable injection hole type fuel injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable injection hole type fuel injection nozzle, capable of suppressing change of an injection angle as well as reducing swirl flow in an injection hole 15 by preventing generation of turbulence on flow of fuel, which flows from a fuel passage 11 to the injection hole 15, as well as varying an injection hole cross sectional area and improving engine combustion characteristics. SOLUTION: In the variable injection type fuel injection nozzle notice is made on changing of the injection angle, of a length L of the injection hole 15, or of the shape of parts such as a rotary valve 21 in an injection hole variable mechanism, and which is provided with a nozzle body 8 on which the injection hole 15 and a seat surface 17 connected to the injection hole 15 are formed, and the injection hole variable mechanism 10 capable of changing the opening cross sectional area of the injection hole 15 a flow passage angle θ, formed by the injection hole 15 and the seat surface 17, is set to a nearly right angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable injection hole type fuel injection nozzle, and more particularly to a fuel injection nozzle for supplying fuel to a diesel engine or other internal combustion engine in an atomized state. The present invention relates to a variable injection hole type fuel injection nozzle whose cross-sectional area can be changed.

[0002]

2. Description of the Related Art Conventionally, for the purpose of improving engine performance, reducing exhaust gas such as nitrogen oxides (NOx) and smoke, and reducing combustion noise, the diameter of the injection nozzle of a diesel injection nozzle has been optimized. I have been. However, if the nozzle hole diameter remains constant regardless of changes in the operating range of the engine as in the past, there is a problem in improving exhaust gas performance.Therefore, the nozzle hole diameter is changed according to the engine load and rotation speed. Research reports and patent applications on a variable injection hole type fuel injection nozzle having an injection hole variable mechanism have been made. For example, Japanese Patent Application Laid-Open No. 10-196490
And Japanese Patent Application No. Hei 10-375881.

[0003] Japanese Patent Application No. 10-375881 employs a rotary valve or the like as an injection hole variable mechanism. An outline will be given based on FIG. 11 to FIG. FIG. 11 is a schematic view of, for example, a jerk type fuel injection device 1 employing a conventional variable injection hole type fuel injection nozzle. The fuel injection device 1 includes a fuel injection pump 2 and a variable injection hole type fuel injection nozzle. It has a nozzle 3, an injection amount sensor 4, and a control unit 5.

[0004] The fuel injection pump 2 pressurizes fuel from a fuel tank (not shown) and supplies the fuel to a fuel introduction section 6 of a fuel injection nozzle 3.

The fuel injection nozzle 3 includes a nozzle housing 7 having a fuel introduction portion 6 formed therein, a nozzle body 8 attached to the nozzle housing 7, a needle valve 9 reciprocatingly sliding within the nozzle body 8, and an injection hole variable mechanism. And 10.
A fuel passage 11 is formed in the nozzle housing 7 from the fuel introduction section 6 to the nozzle body 3, and a fuel reservoir chamber 12 is formed.
In the above, pressure can be applied to the pressure receiving portion 13 of the needle valve 9.

FIG. 12 is an enlarged sectional view taken along the line XII of FIG. 11 when the needle valve 9 is seated. FIG. 13 is an enlarged sectional view taken along the line XIII-XIII of FIG. A hole 14 is formed at the tip of the nozzle body 8, and a plurality of (for example, five) injection holes 15 are formed on the peripheral wall of the hole 14 at equal angular intervals.

[0007] When the seat is in the seat, the seat portion 16 of the needle valve 9 seats on the seat surface 17 on the upstream side of the injection hole 15 of the nozzle body 8, so that the fuel passage 11 and the fuel passage 11 from the fuel introduction portion 6 are connected. The injection hole 15 is blocked. The needle valve 9 in the fuel storage chamber 12 (FIG. 11)
When the pressure receiving portion 13 receives the fuel pressure from the fuel injection pump 2, the needle valve 9 lifts up against the urging force of the valve spring 18 and injects fuel from the injection hole 15.

The control means 5 drives an actuator 19 (for example, a rotary solenoid or a stepping motor) of the injection hole variable mechanism 10 in response to a fuel pressure detection signal from the injection amount sensor 4, and the fuel injection nozzle 3
Is controlled in the injection hole variable mechanism 10 in FIG.

The variable injection hole mechanism 10 includes an actuator 19
And a drive shaft 20 attached to the actuator 19, and a rotary valve 21 integrally formed at the tip of the drive shaft 20. The drive shaft 20 is inserted into the inside of the needle valve 9 from the top of the nozzle housing 7 and reaches the lower part thereof. The drive shaft 20 uses a rotary valve 21
Can be transmitted to FIG. 14 is a perspective view of the rotary valve 21. The rotary valve 21 has a substantially conical shape tapered downstream, which is located below the needle valve 9 and can be engaged with the inside of the hole 14. A sheet arc portion 22 capable of closing the injection hole 15, and a variable groove portion 23 having a predetermined volume between the sheet arc portion 22 and communicating with the injection hole 15.
(Introduction fuel passage) (five in the example shown).

When the needle valve 9 is seated, the rotary valve 21 is rotatable around its axis.
When the seat arc portion 22 of the rotary valve 21 is opposed to the injection hole 15, the injection hole 15 is closed, and when the variable groove portion 23 faces the injection hole 15, the fuel passage 1 is lifted by the needle valve 9.
1 and the injection hole 15 can be communicated via the variable groove 23.

In FIG. 13, by rotating the rotary valve 21 clockwise or counterclockwise, the relative position of the variable groove 23 of the rotary valve 21 with respect to the injection hole 15 in the nozzle body 8 (hole 14) is made variable. In addition, the sheet arc portion 22 blocks a predetermined ratio of the opening cross-sectional area at the inlet portion of the injection hole 15 and can change the opening degree of the injection hole 15.

In the variable injection hole type fuel injection nozzle 3 or the injection hole variable mechanism 10 having such a configuration, the injection hole variable mechanism 10
Thus, the opening cross-sectional area of the injection hole 15 can be made variable, so that it becomes possible to obtain injection characteristics according to the load state or the rotation state of the engine.

However, if the opening cross-sectional area (injection hole diameter) of the injection hole 15 is reduced according to the rotation of the rotary valve 21, that is, if the injection hole opening degree is reduced, the seat surface 17 of the nozzle body 8 and the rotary valve 21 can be changed. The fuel that reaches the injection hole 15 from the space between the nozzle hole 23 and the injection hole 15 does not pass through the opening that is not shielded by the sheet arc 22 at the entrance of the injection hole 15 (that is, the opening that is offset from the axis of the injection hole 15). Therefore, a swirling flow around the axis is generated inside the injection hole 15, and the actual injection angle (spray angle) is smaller than the actual injection angle α (FIG. 12) between the injection holes 15 in the axial direction of the nozzle body 8. Angle) may be large. Alternatively, the spread angle (injection angle) of the fuel injected from each injection hole 15 may be larger than a predetermined angle.

If the injection direction or the injection angle is larger than the injection hole angle α, it is considered that this may cause deterioration of the combustion characteristics during engine combustion.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and provides a variable injection hole type fuel injection nozzle capable of improving the engine combustion characteristics by changing the injection hole cross-sectional area. As an issue.

Another object of the present invention is to provide a variable injection hole type fuel injection nozzle capable of reducing a swirling flow inside the injection hole and suppressing a change in injection angle.

It is another object of the present invention to provide a variable injection hole type fuel injection nozzle capable of suppressing the occurrence of a swirling flow inside the injection hole by minimizing the flow of fuel from the fuel passage toward the injection hole. Make it an issue.

[0018]

That is, the present invention focuses on changing the injection hole angle, changing the injection hole length, or changing the shape of a component such as a rotary valve in the injection hole variable mechanism. In the first invention,
A variable injection hole type fuel injection nozzle, comprising: a nozzle body having an injection hole and a sheet surface connected to the injection hole; and an injection hole variable mechanism capable of changing an opening cross-sectional area of the injection hole. A variable injection hole type fuel injection nozzle, characterized in that a flow passage angle formed between the injection hole and the seat surface is substantially perpendicular.

The shape of the sheet surface can be changed so as to be orthogonal to the injection hole.

The injection hole angle of the injection hole can be changed so as to be orthogonal to the sheet surface.

The injection hole variable mechanism has a rotary valve capable of seating on the seat surface, and a drive shaft for driving the rotary valve. The rotary valve is rotated to open the opening of the injection hole. The cross-sectional area can be varied.

A second invention has a nozzle body having an injection hole and a hole formed with a sheet surface connected to the injection hole, and an injection hole variable mechanism capable of changing an opening sectional area of the injection hole. A variable injection hole type fuel injection nozzle, wherein a length of the injection hole is 4.8 times or more of a diameter of the injection hole.
It is a variable injection hole type fuel injection nozzle characterized by having a ratio of 5.8.

The above-described injection hole variable mechanism is not limited to the one using a rotary valve, and any injection hole variable mechanism that can partially block the inlet portion of the injection hole at a predetermined ratio, for example, Other arbitrary ones can be adopted, such as using a member that slides with respect to the inlet portion of the injection hole.

In the variable injection hole type fuel injection nozzle according to the present invention, particularly in the first invention, the angle of the angle changing portion of the fuel passage from the sheet surface in the hole at the tip end portion of the nozzle body to the injection hole (flow path angle) ) Is made almost perpendicular, so that the swirl flow component is not easily generated in the fuel flowing into the injection hole from the seat surface at the tip of the nozzle body, and the swirl flow inside the injection hole is suppressed. The injection angle (spray angle) of the injected fuel can be maintained substantially constant in accordance with the injection hole angle of the injection hole without expanding.

In the second invention, the ratio of the injection hole length to the injection hole diameter is 4.8 to 5.
Since the length is about 8, the period or length of the fuel flowing inside the injection hole is made longer than before, and the swirl flow that may occur is eliminated when reaching the outlet of the injection hole, and the swirl flow is generated. The expansion of the spray angle can also be suppressed.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a variable injection hole type fuel injection nozzle according to the present invention will be described. In order to make a comparison with the conventional variable injection hole type fuel injection nozzle 3 described in FIGS. 11 to 14, the conventional variable injection hole type fuel injection nozzle 3 is used as a model 1 and the variable injection hole type fuel injection nozzle according to the present invention is used. 3
Are model 2 (variable hole type fuel injection nozzle 30), model 3 (variable hole type fuel injection nozzle 31), model 4 (variable hole type fuel injection nozzle 32), and model 5 (variable hole type fuel injection nozzle 30). 33). However, the same parts as those in FIGS. 11 to 14 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 1 is a sectional view of a main part of a conventional variable injection hole type fuel injection nozzle 3 (model 1), and FIG. 2 is a variable injection hole type fuel injection nozzle 30 according to the present invention (second invention).
FIG. 3 is a sectional view of a main part of (model 2), and FIG. 3 is a variable injection hole type fuel injection nozzle 31 (model 3) according to the present invention (second invention).
FIG. 4 is a sectional view of a main part of a variable injection hole type fuel injection nozzle 32 (model 4) according to the present invention (first invention), and FIG. 5 is a sectional view of the main part of the present invention (first invention). It is principal part sectional drawing of the variable injection hole type fuel injection nozzle 33 (model 5).

FIG. 6 shows each model 1, 2, 3,
4 and 5, namely, the injection hole angle α, the angle of の of the injection hole angle α, the cone angle β of the rotary valve 21 with respect to the axis of the seat arc portion 22, and the seat arc portion 22 of the rotary valve 21. (That is, the seat surface 17 of the nozzle body 8) and the flow path angle θ formed by the injection hole 15 and the ratio L / L of the length L to the diameter D of the injection hole 15.
It is the chart which summarized D. That is, in the model 1 (conventional variable injection hole type fuel injection nozzle 3), the injection hole angle α is 145.
, 1/2 of α is 72.5 degrees, the cone angle β of the rotary valve 21 is 30 degrees, the flow path angle θ between the rotary valve 21 and the injection hole 15 is 77.5 degrees, and the ratio L / D is the same as before. 3.9. The same applies to other models 2, 3, 4, and 5 according to the present invention. That is, Model 2 (variable injection hole type fuel injection nozzle 30) (FIG. 2) is the same as the conventional one except that the ratio L / D is 4.8. Model 3 (variable injection hole type fuel injection nozzle 31) (FIG. 3) is the same as the conventional one except that the ratio L / D is 5.8. Model 4 (variable injection hole type fuel injection nozzle 32) (FIG. 4) has a ratio L / D of 3.9 and an injection hole angle α of 145.
The angle is the same as the conventional one, but the flow path angle θ between the rotary valve 21 and the injection hole 15 is set to 90 degrees, and the cone angle β of the rotary valve 21 is set to 17.5 degrees so as to match this. Model 5 (variable injection hole type fuel injection nozzle 3
3) (FIG. 5) shows that the ratio L / D is 3.9, and the cone angle β of the rotary valve 21 is 30 degrees, which is the same as the conventional one. The flow path angle θ between the rotary valve 21 and the injection hole 15 is set to 8
It is 7.5 degrees (almost right angle).

Numerical analysis of the fuel flow was performed on the models 1, 2, 3, 4, and 5 as described above. FIG. 7 shows that for the models 1, 2, and 3, the rotary valve 21 is rotated at a predetermined angle around the axis, that is, at 10, 15, 20, and 2 degrees.
It is a chart showing the result of having calculated by numerical analysis the opening degree (for example, 100% is a full open state) of the injection hole 15 and the fuel injection angle (spray angle) at that time rotated by 25 degrees and 25 degrees. FIG. 8 is a graph showing the results of FIG. 7 with the horizontal axis representing the rotation angle of the rotary valve 21 and the vertical axis representing the spray angle.

As can be seen from FIGS. 7 and 8, the length of the injection hole 15 in the model 2 is 1.25 times (L / D = 4.8), and the length in the model 3 is 1.25. Although it is five times (L / D = 5.8), if the length of the injection hole 15 is increased so as to increase the ratio L / D, the rotation angle of the rotary valve 21 becomes 22.5 degrees, 25
In the case of the degree, the change of the injection angle is smaller than that of the model 1, that is, the deviation from the injection hole angle α (= 145 degrees) can be reduced.

When the opening of the injection hole 15 is reduced by rotating the rotary valve 21, a strong swirling flow is generated inside the injection hole 15.
5, the fuel injection angle at the outlet is upward as compared to the injection hole angle α.
It is considered that when the length of the nozzle 5 was increased, the flow further rotated inside the injection hole 15 and the injection angle became lower than that in the model 1.

Next, the model 4 is a rotary valve 21
The shape of the rotary valve 21 was changed so that the seat circular arc portion 22 was perpendicular to the axis of the injection hole 15, and numerical analysis of the flow was performed in the same manner as described above. Model 5
Is a model in which the injection hole angle is set to 125 degrees so that the flow path angle θ formed between the injection hole 15 and the rotary valve 21 approaches a right angle. FIG.
6 is a table showing the results of numerical analysis on models 1 and 4. FIG. 10 is a graph showing the result of FIG. 9 and the result of Model 5.

As shown in FIG. 9 and FIG.
It can be confirmed that even when the rotary valve 21 is rotated, the injection angle hardly changes. This is because the injection hole 15 and the rotary valve 21 are made orthogonal to each other at the inlet portion from the variable groove 23 of the rotary valve 21 to the injection hole 15, thereby forming the injection hole 1.
It is considered that the pressure generated on the left and right walls of the flow path at the inlet portion of the nozzle 5 becomes substantially equal, and the swirling flow that may be generated in the injection hole 15 can be reduced. Further, by setting the injection hole angle θ to 125 degrees, the flow path angle θ
Is approximately 90 degrees (87.5 degrees), the rotary valve 21 is also compared with the conventional model 1.
It can be confirmed that the change in the injection angle from the injection hole angle α (= 125 degrees) when rotating is small. This equalizes the flow at the inlet of the nozzle hole 15 as much as possible, as in the case of the model 4, and
It is considered that the swirl flow which may occur in the inside of the fuel cell was reduced.

[0033]

As described above, according to the present invention, by making the flow path angle between the injection hole and the rotary valve or the seat surface closer to a right angle, or by making the injection hole length longer than before, etc. It is possible to suppress the generation of the swirling flow inside the injection hole, prevent a large change in the injection angle, and contribute to the improvement of the engine combustion characteristics.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a conventional variable injection hole type fuel injection nozzle 3 (model 1).

FIG. 2 is a sectional view of a main part of a variable injection hole type fuel injection nozzle 30 (model 2) according to the present invention (second invention).

FIG. 3 is a sectional view of a main part of a variable injection hole type fuel injection nozzle 31 (model 3) according to the present invention (second invention).

FIG. 4 is a sectional view of a main part of a variable injection hole type fuel injection nozzle 32 (model 4) according to the present invention (first invention).

FIG. 5 is a sectional view of a main part of a variable injection hole type fuel injection nozzle 33 (model 5) according to the present invention (first invention).

FIG. 6 shows specifications for models 1, 2, 3, 4, and 5;
That is, the injection hole angle α, the angle of の of the injection hole angle α, the cone angle β with respect to the axis of the seat arc portion 22 in the rotary valve 21, the seat arc portion 22 of the rotary valve 21 (the seat surface 17 of the nozzle body 8). 5 is a table summarizing the flow path angle θ formed by the injection holes 15 and the ratio L / D of the length L to the diameter D of the injection holes 15.

FIG. 7 shows the rotation of the rotary valve 21 at a predetermined angle around the axis, ie, 10 degrees, 15 degrees, for models 1, 2, and 3.
, 20 degrees, 22.5 degrees, and 25 degrees, and the results of numerical analysis of the opening degree (for example, 100% is fully open) of the injection hole 15 and the fuel injection angle (spray angle) at that time are shown. FIG.

8 is a graph showing the results of FIG. 7 with the horizontal axis representing the rotation angle of the rotary valve 21 and the vertical axis representing the spray angle.

FIG. 9 is a table showing the results of the same numerical analysis as in FIG. 7 for models 1 and 4;

FIG. 10 is a graph showing the result of FIG. 9, and the result of Model 5, similarly to FIG.

FIG. 11 is a schematic view of, for example, a jerk type fuel injection device 1 employing a conventional variable injection hole type fuel injection nozzle.

12 is the same as FIG. 11 when the needle valve 9 is seated.
2 is an enlarged sectional view of a part XII of FIG.

FIG. 13 is an enlarged sectional view taken along line XIII-XIII of FIG.

14 is a perspective view of the rotary valve 21. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Jerk type fuel injection device (FIG. 11) 2 Fuel injection pump 3 Variable injection hole type fuel injection nozzle (FIG. 12, FIG. 1) (model 1) 4 Injection amount sensor 5 Control means 6 Fuel introduction part 7 Nozzle housing 8 Nozzle Body 9 Needle valve 10 Injection hole variable mechanism 11 Fuel passage 12 Fuel reservoir 13 Pressure receiving portion of needle valve 9 Hole at tip of nozzle body 8 15 Injection hole 16 Seat portion of needle valve 9 17 Seat surface of nozzle body 8 18 Valve spring 19 Actuator 20 Drive shaft 21 Rotary valve 22 Seat arc of rotary valve 21 Variable groove (introduction fuel passage) of rotary valve 21 Variable injection hole type fuel injection nozzle (model 2) (FIG. 2)
(Second Invention) 31 Variable Injection Hole Type Fuel Injection Nozzle (Model 3) (FIG. 3)
(Second Invention) 32 Variable Injection Hole Type Fuel Injection Nozzle (Model 4) (FIG. 4)
(First Invention) 33 Variable Injection Hole Type Fuel Injection Nozzle (Model 5) (FIG. 5)
(First Invention) α Injection hole angle formed between the injection holes 15 in the axial direction of the nozzle body 8 β Cone angle with respect to the axis of the seat arc portion 22 of the rotary valve 21 θ Seat arc portion 22 of the rotary valve 21 (that is, the nozzle body) 8) The flow path angle formed by the sheet surface 17) and the injection hole 15 L / D The ratio of the length L to the diameter D of the injection hole 15

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G066 AA07 AB02 AD12 BA01 CC05U CC06T CC14 CC20 CC23 CC26 CC48 CD30 CE13 CE21 CE22

Claims (5)

[Claims] 1. A variable injection hole type fuel injection nozzle comprising: a nozzle body having an injection hole and a sheet surface connected to the injection hole; and an injection hole variable mechanism capable of changing an opening cross-sectional area of the injection hole. A variable injection hole type fuel injection nozzle, wherein a flow path angle between the injection hole and the seat surface is substantially perpendicular. 2. The variable injection hole type fuel injection nozzle according to claim 1, wherein the shape of the seat surface is changed so as to be orthogonal to the injection hole. 3. The variable injection hole type fuel injection nozzle according to claim 1, wherein an injection hole angle of the injection hole is changed so as to be orthogonal to the seat surface. 4. The injection hole variable mechanism includes: a rotary valve capable of seating on the seat surface; a drive shaft for driving the rotary valve;
The variable injection hole type fuel injection nozzle according to claim 1, wherein the opening cross-sectional area of the injection hole is changed by rotating the rotary valve. 5. A variable injection hole type including: a nozzle body having an injection hole and a hole having a sheet surface connected to the injection hole; and an injection hole variable mechanism capable of changing an opening cross-sectional area of the injection hole. A fuel injection nozzle, wherein a length of the injection hole is 4.8 times to 5.8 times a diameter of the injection hole.
A variable injection hole type fuel injection nozzle characterized by being doubled.