JPH10318092A - Fuel injection nozzle - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide a fuel injection nozzle for suppressing eccentricity of a needle valve which repeats contact and separation with a seat portion of a nozzle body. A large-diameter cylindrical portion (32) having the same outer diameter extends from one end to the other end of the needle valve (31) in the axial direction, and the large-diameter cylindrical portion (32) extends in the axial direction through a clearance on the outer periphery. Long straight guide hole 12 with inner diameter
Slidable on the inner wall. Therefore, the needle valve 3
The amount of eccentricity of the needle valve 31 is regulated during the repetitive operation of contacting and separating the nozzle body 11 with the valve seat 13. For this reason, the fuel injected from the injection hole of the nozzle body 11 ensures a uniform spray state in both quantity and quality. Further, the processing of the fuel injection nozzle is easy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel injection nozzle for an internal combustion engine.

[0002]

2. Description of the Related Art One of the generation factors of a soluble organic component SOF contained in particulates contained in exhaust gas of a diesel engine is that fuel leaked from a suck hole of a fuel injection nozzle after fuel injection ends is an unburned component. It is known to be discharged as. It is known that reducing the volume of the suck hole of the fuel injection nozzle is effective in reducing the soluble organic component SOF.

[0003] A valve covered orifice nozzle (VCO nozzle) known as a well-known technique in which the volume of the suck hole is reduced as much as possible has an injection hole in a valve seat portion which contacts a needle valve when the valve is closed. This prevents the fuel from leaking from the suck hole formed at the tip of the nozzle body after the end of fuel injection.

[0004]

However, in such a conventional fuel injection nozzle, when the needle valve abuts and the nozzle body valve seat come into contact with each other when the valve is closed, an oil-tightness is ensured. Because of the injection hole, the needle valve abutment is located very close to the injection hole at the beginning of injection, that is, when the needle valve abutment is separated from the nozzle body valve seat, and the part that guides the needle valve is separated. Position, the axis of the needle valve and the axis of the nozzle body tend to be eccentric. Then, since the shape and volume of the space in the vicinity of the injection hole differ between the injection holes, the spray form of the fuel injected from the injection hole becomes non-uniform.

[0005] In order to equalize the fuel spray injected from the plurality of injection holes of the fuel injection nozzle, a guide portion of the nozzle body in which the needle valve is loosely fitted, and a valve seat portion in which the contact portion of the needle valve is seated. In addition, it is necessary to improve the accuracy of the coaxiality of the three axes with the sliding portion of the needle valve loosely fitted to the guide portion.

However, it is difficult to maintain the basic structure of a conventional fuel injection nozzle and improve the accuracy of the above-described three-axis coaxiality by machining. If the needle valve accommodated in the guide hole of the nozzle body is eccentric, the amount of fuel injected from the injection hole at the tip of the nozzle, the shape of the spray, the quality of the spray, and the like become uneven among the injection holes. Due to the non-uniformity of the fuel spray injected from the holes, it is difficult for the desired combustion to be performed in the combustion chamber, resulting in an increase in black smoke emission.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection nozzle which suppresses eccentricity of a needle valve which repeatedly contacts and separates from a seat portion of a nozzle body. It is another object of the present invention to provide a fuel injection nozzle that makes the quantity and quality of the fuel sprayed from the fuel injection nozzle uniform. Still another object of the present invention is to provide a fuel injection nozzle for an internal combustion engine which is easy to process and reduces the soluble organic component SOF.

[0008]

According to the fuel injection nozzle of the first aspect of the present invention, a large-diameter cylindrical portion having the same outer diameter from one end to the other end of the needle valve extends in the axial direction, Since this large-diameter cylindrical portion can slide on the inner wall of a straight guide hole that extends long with the same inner diameter in the axial direction through a clearance on the outer periphery, the needle valve comes into contact with and separates from the valve seat portion of the nozzle body. The eccentric amount of the needle valve is regulated during the repetitive operation. For this reason, the fuel injected from the injection hole of the nozzle body ensures a uniform spray state in both quantity and quality.

According to the fuel injection nozzle of the present invention, one end of the axially extending groove in the inner wall of the guide hole of the nozzle body is located in the fuel reservoir space, and the other end is the valve seat. This groove functions as a fuel passage because it is located near the portion. According to the fuel injection nozzle according to the third aspect of the present invention, one end of the groove extending in the axial direction on the outer periphery of the needle valve is located in the fuel reservoir space, and the other end of the groove is located near the valve seat. And the large-diameter cylindrical portion excluding the groove portion slides on the inner wall of the guide hole via a clearance. The groove extending in the axial direction functions as a fuel passage.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) A first embodiment of the present invention is shown in FIGS. As shown in FIGS. 1, 2 and 3, the fuel injection nozzle 10 includes a nozzle body 11 and the nozzle body 11.
And a needle valve 31 which can slide back and forth in the axial direction.

The nozzle body 11 is a hollow cylinder having a basic shape with a bottom, and has a guide hole 12, a valve seat 13, and an injection hole 2 therein.
2, 23, 24, 25, sack part 15, fuel pool 16,
The fuel supply hole 17 and the grooves 18, 19, 20, 21 are formed. The guide hole 12 extends in the axial direction inside the nozzle body 11, and has one end connected to the open end 26 of the nozzle body 11 and the other end connected to the valve seat 13. . The inner wall of the guide hole 12 has the same inner diameter from the open end 26 of the nozzle body 11 to the vicinity of the valve seat 13 on the bottom side.

The valve seat 13 has a truncated conical surface, one end on the large diameter side is continuous with the guide hole 12, and the other end on the small diameter side is connected to the sack portion 15. The contact portion 36 of the needle valve 31 can contact the valve seat 13. The contact portion 36 has a circular shape in theory. The sack portion 15 is a sack hole formed in a bag-like shape with a small space volume at the tip end side of the nozzle body 11. The opening side of the suck hole is the valve seat 1
3 is continued on the small diameter side.

The injection holes 22, 23, 24, 25 communicate with the inside and outside of the nozzle body 11, and in this embodiment, as shown in FIG.
They are provided at equal intervals of 0 degrees. Each injection hole 22, 2
3, 24 and 25 have the same inner diameter. As the present invention,
The position, number, inclination angle, inner diameter, shape, and the like of these injection holes are not limited to the above. Injection holes 22, 23, 24, 2
The inside opening of 5 is located at a part of the frusto-conical surface of the valve seat 13, and is located on the tip side of the contact portion 36 of the needle valve 31.

The fuel reservoir 16 is formed in an annular shape in the middle of the inner wall where the guide hole 12 of the nozzle body 11 is formed.
A fuel supply hole 17 for supplying fuel from outside is connected to the fuel reservoir 16. Grooves 18, 19, 20, 21
Extends straight in the axial direction on the inner wall of the nozzle body 11 and has a substantially semicircular cross-sectional shape. Groove 18, 1
Most of 9, 20, 21 face a part of the outer periphery of the large-diameter cylindrical portion 32 of the needle valve 31, which is loosely fitted in the guide hole 12. One end of each of the grooves 18, 19, 20, and 21 communicates with the fuel reservoir 16, and the other end thereof is located at a position exceeding the small-diameter cylindrical portion 34. The grooves 18, 1
The volumes of 9, 20, and 21 near the injection-hole-side end are positions where the small-diameter cylindrical portion 34 of the needle valve 31 faces when the needle valve 31 is seated.

The needle valve 31 has a solid cylindrical shape as its basic shape. As shown in FIG. 8, a large-diameter cylindrical portion 32, an inclined portion 33, a small-diameter cylindrical portion 34, a truncated cone portion 35, a contact portion 36,
And a conical portion 37. The large-diameter cylindrical portion 32 has the same outer diameter and has a guide hole 1 from the opening end 26 side of the nozzle body 11.
2 to the vicinity of the terminal end 121. An intermediate portion of the large-diameter cylindrical portion 32 faces the fuel reservoir 16. The large-diameter cylindrical portion 32 is loosely fitted into the guide hole 12 via a clearance from the portion beyond the open end 26 to the vicinity of the terminal end 121 of the guide hole 12. When the needle valve 31 reciprocates in the axial direction with respect to the nozzle body 11 because the inner wall of the guide hole 12 of the nozzle body 11 extends in the axial direction, the eccentricity of the axis of the needle valve 31 with respect to the nozzle body 11 is reduced. Is slight. There is no substantial eccentricity of the needle valve 31 with respect to the nozzle body 11. Therefore, in the present embodiment, since there is no eccentric deflection of the needle valve 31, good injection characteristics with uniform quality and quantity of injection from the injection holes 22, 23, 24, 25 can be obtained.

The inclined portion 33 is a portion which is formed on the frustoconical surface and is continuous with the distal end of the large-diameter cylindrical portion 32. The large-diameter cylindrical portion 32 side of the inclined portion 33 is continuous with the small-diameter cylindrical portion 34. The small-diameter cylindrical portion 34 has an axial length of the large-diameter cylindrical portion 3.
2 is considerably shorter than the axial length. This is to eliminate the substantial eccentricity of the needle valve 31 by increasing the axial length of the large-diameter cylindrical portion 32 as much as possible, and to further restrict the flow of fuel through the grooves 18, 19, 20, 21. This is to form the fuel passage 38 which is sufficiently ensured. The distal end side of the small-diameter cylindrical portion 34 is continuous with the truncated cone portion 35.

The frusto-conical portion 35 has one end continuous with the small-diameter cylindrical portion 34 and the other end circular contact portion 36.
Through the conical portion 37. This truncated cone 35
The side surface of the truncated cone has a smaller inclination angle than the inclination angle of the valve seat 13 as shown in FIG. The connecting portion between the truncated conical portion 35 and the conical portion 37 is a circle, and this circular portion becomes the contact portion 36. FIG. 5 shows that the needle valve 31 is
Indicates a state in which the contact has occurred. The contact portion 36 is in contact with the valve seat 13. When the contact portion 36 is separated from the valve seat portion 13 in the axial direction, as shown in FIG. 6, the fuel flows from the fuel passage 39 to the injection hole side.

The conical portion 37 has a larger inclination angle than the inclination angle of the valve seat 13. This is the contact portion 36 when the valve is closed.
And the valve seat 13 so that the oil tightness can be secured. The tip of the conical portion 37 is at a position facing the sack portion 15 when the valve is closed. When the fuel is cut off, the contact portion 36 of the needle valve 31 is in contact with the valve seat 13 as shown in FIG. Therefore, no fuel is injected from the injection holes 22, 23, 24, 25.

At the time of fuel injection, the needle valve 31 is separated from the nozzle body 11 in the axial direction. In this separated state, the fuel is supplied from the fuel supply hole 17, the fuel reservoir 16, the grooves 18, 19, 20, 21, the guide hole 12, the valve seat 13,
It is injected to the outside through the injection holes 22, 23, 24, 25. According to the first embodiment, since the eccentricity of the needle valve 31 with respect to the nozzle body 11 does not substantially occur, the axis of the needle valve 31 and the axis of the valve seat 13 coincide on the same axis. Holes 21, 22, 23, 24, 2
The quantity and quality of the fuel injected from 5 becomes uniform.

(Second Embodiment) FIG. 7 shows a second embodiment of the present invention.
And FIG. In the second embodiment shown in FIGS. 7 and 8, the guide hole 12 formed in the nozzle body 11 has an open end 2.
6 are formed to have the same inner diameter from the vicinity of the valve seat 13. On the other hand, the needle valve 31 has a large-diameter cylindrical portion 32 that extends long in the axial direction. One end of the large-diameter cylindrical portion 32 is located outside beyond the open end 26, and the other end 323
Is continuous with the truncated cone 35. At the terminal end 322 connected to the truncated cone 35, the same inner diameter of the large-diameter cylinder ends.

On the outer periphery of the needle valve 31, grooves 51, 52, 53 and 54 having a semicircular cross section are formed. One end of these grooves 51, 52, 53, 54 ends inside the fuel reservoir 16, and the other end penetrates to the truncated cone of the truncated cone 35. Thereby, the fuel passage 58 is secured. According to this second embodiment,
A state in which the portion of the large-diameter cylindrical portion 32 of the needle valve 31 where the groove is not formed is loosely fitted to the inside of the nozzle body 11 through the clearance of the inner wall of the guide hole 12 for a long distance. Therefore, the eccentricity of the needle valve 31 with respect to the nozzle body 11 is eliminated.

At the initial stage of fuel injection, the axis of the frusto-conical portion 35 and the conical portion 37 of the needle valve 31 from the valve seat 13 is the same axis, so that the amount of fuel injected from the plurality of injection holes 22 and 24 is increased. And the shape and normality are uniform in both quantity and quality. Therefore, the soluble organic component SO in the particulates contained in the exhaust gas of the diesel engine
F can be reduced. In particular, in this example,
The volume of the sack portion 15 is sufficiently small, and the drooping is reduced.
Since the fuel is uniformly injected from the nozzles 23, 24, and 25, the fuel spray is made uniform and the combustion in the combustion chamber is effectively performed.

Comparative Example FIG. 9 shows a comparative example. In the comparative example shown in FIG. 9, a guide hole 71 is formed inside the nozzle body 11, and a needle valve 72 is loosely fitted into the guide hole 71. The needle valve 72 includes a large-diameter cylindrical portion 73 and a small-diameter cylindrical portion 74.

The large-diameter cylindrical portion 73 is loosely fitted to the inner wall of the guide hole 71. A sufficiently large cylindrical space 91 is formed between the small-diameter cylindrical portion 74 and the guide hole 71. This cylindrical space functions as a fuel passage. However, in the initial stage of fuel injection, eccentric deflection of the needle valve 72 separated from the valve seat 13 occurs. In particular, immediately after the contact portion 75 of the needle valve 72 is separated from the valve seat 13, the frustoconical portion 7
Since the axis of 6 is easily shifted from the axis of the valve seat 13, the volume of the injection holes 78 and 79 on the inlet side becomes non-uniform, so that the spray form of the injected fuel injected from the injection holes 78 and 79 is changed. It becomes uneven.

On the other hand, in the present invention, as described above, the large-diameter cylindrical portion of the needle valve extends in the axial direction with the same diameter from one end to the other end, and the large-diameter cylindrical portion is provided with the outer peripheral clearance. Slidable on the inner wall of a straight guide hole that extends long with the same inner diameter in the axial direction, thereby restricting the amount of eccentricity of the needle valve during repeated operation of contact and separation with the valve seat of the needle valve. You. For this reason, the fuel injected from the injection hole of the nozzle body ensures a uniform spray state in both quantity and quality.

[Brief description of the drawings]

FIG. 1 is a sectional view of a fuel injection nozzle according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II shown in FIG.

FIG. 3 is an enlarged sectional view of a tip of a fuel injection nozzle according to a first embodiment of the present invention.

FIG. 4 is a schematic explanatory view showing a fuel injection direction according to the first embodiment of the present invention.

FIG. 5 is a schematic explanatory diagram illustrating a valve closing state of a fuel injection nozzle according to the first embodiment of the present invention.

FIG. 6 is a schematic explanatory diagram illustrating a valve opening state of a fuel injection nozzle according to the first embodiment of the present invention.

FIG. 7 is a sectional view of a fuel injection nozzle according to a second embodiment of the present invention.

FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 7 of the second embodiment of the present invention.

FIG. 9 is a sectional view showing a fuel injection nozzle according to a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Nozzle body 12 Guide hole 13 Valve seat part 15 Suck part 16 Fuel reservoir 17 Fuel supply hole 18, 19, 20, 21 Groove part 22, 23, 24, 25 Injection hole 31 Needle valve 32 Large diameter cylindrical part 33 Inclined part 34 Small diameter Cylindrical part 35 Truncated cone part 36 Contact part 37 Conical part

Claims (3)

[Claims] 1. A nozzle body having a guide hole, a valve seat, and an injection hole having inner walls of the same diameter, a large-diameter cylindrical portion guided in a circumferential direction and an axial direction through a clearance on the guide hole inner wall, and A needle valve having a diameter smaller than the large-diameter cylindrical portion and having a contact portion capable of contacting the valve seat portion. 2. The nozzle body has a groove extending in the axial direction in the inner wall of the guide hole, and one end of the groove is located in a fuel reservoir space, and the other end is in the vicinity of the valve seat. The needle valve has a small-diameter cylindrical portion on the contact portion side of the large-diameter cylindrical portion, and a frustoconical portion on the large-diameter cylindrical portion side of the contact portion. A fuel injection nozzle as described. 3. The needle valve has a groove extending in the axial direction on the outer periphery, and one end of the groove is located in the fuel reservoir space, and the other end is located near the valve seat. ,
2. The fuel injection nozzle according to claim 1, wherein a portion excluding the groove is the large-diameter cylindrical portion that slides on the inner wall of the guide hole via a clearance. 3.