JP2002349393A - Fuel injection nozzle and its processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection nozzle capable of materializing an injection according to the operation condition of an engine, reducing NOx, black smoke and HC, and further improving fuel economy and output. SOLUTION: A method for processing the fuel injection nozzle comprises processing the inner wall of an inlet 31a of an injection hole 31 using a processing needle 10 fittingly insertable into a nozzle body 3 while supplying a grinding fluid from the upstream of a turning flow forming part 11 for generating the turning flow of the grinding fluid to provide a circumferential component to the fluid flow and then flowing the fluid out of the injection hole 31. Thereby, the inlet 31a can be formed in an asymmetric form in which a fuel can easily flow in the injection hole 31. By this method, the fuel flow rate from the side ready to flow in the injection hole 31 can be made higher than that hard to flow therein to enable the generation of turning flow in the hole 31. Therefore, a fuel atomization can be promoted in a simple construction without increasing the number of components, and fuel economy and output can be improved while reducing NOx, black smoke and HC.

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 and a processing method thereof, and more particularly to a fuel injection nozzle of a fuel injection valve for an internal combustion engine (hereinafter referred to as an "internal combustion engine") and a processing method thereof.

[0002]

2. Description of the Related Art Conventionally, a valve needle is accommodated in a nozzle body so as to be reciprocally movable, and a contact portion of the valve needle is seated on a valve seat formed on the nozzle body and is separated from the valve seat, thereby injecting. 2. Description of the Related Art There is known a fuel injection nozzle of an engine fuel injection valve for intermitting fuel injected from a hole.

[0003] In such a fuel injection nozzle, from the viewpoints of reduction of fuel consumption, improvement of exhaust emission, stable operation of the engine, and the like, "fine atomization of fuel" injected from an injection hole is an important factor. In particular, in the case of a fuel injection nozzle of a fuel injection valve for an in-cylinder direct injection engine, "atomization of fuel" is one of the most important factors. As a fuel injection nozzle of a fuel injection valve for an in-cylinder direct injection engine, for example, as disclosed in Japanese Patent Application Laid-Open No. H8-247000, an end of a fuel inlet side of an injection passage has a roundness with respect to an inner wall. There is known a fuel injection nozzle in which a large radius is formed in an inlet area closer to a round upper pressure chamber and a relatively small radius is formed in an inlet area farther from the lower pressure chamber. Further, as disclosed in JP-A-11-324866, there is known a fuel injection nozzle in which a swirl chamber for generating a swirling flow is formed in a nozzle needle or a nozzle body.

[0004] In the fuel injection nozzle disclosed in Japanese Patent Application Laid-Open No. 8-247000, the flow of fuel in the injection hole is increased as the uniform flow parallel to the injection hole axis to increase the spray penetration force. Further, in the fuel injection nozzle disclosed in Japanese Patent Application Laid-Open No. H11-324866, by changing the strength of the swirl flow supplied to the injection hole inlet according to the lift amount of the nozzle needle, the spray injected from the injection hole is changed. The angle is made variable to control the spray characteristics.

[0005]

However, in the fuel injection nozzle disclosed in Japanese Patent Application Laid-Open No. Hei 8-247000, no specific processing technique is disclosed, and the edge of the injection hole inlet is moved upward and downward. The method of rounding to a different radius is not known, and further, there is a problem that the spray and the flow rate are constant regardless of the operating conditions of the engine. Also, Japanese Patent Application Laid-Open
In the fuel injection nozzle disclosed in Japanese Patent Application Laid-Open No. 1-324866, since a swirl chamber that generates a swirl flow is formed in the nozzle needle or the nozzle body, the swirl flow forming part is complicated, the number of parts increases, and the manufacturing cost increases. There was a problem of rising.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a fuel for supplying a spray corresponding to an operating state of an engine to reduce NOx, black smoke and HC to improve fuel efficiency and output. It is an object to provide an injection nozzle. Another object of the present invention is to provide a fuel injection nozzle capable of promoting atomization of fuel and controlling spray characteristics with a simple configuration without increasing the number of parts. It is another object of the present invention to provide a method of processing a fuel injection nozzle in which an injection hole inlet can be easily formed in a shape in which fuel can easily flow into the injection hole.

[0007]

According to the fuel injection nozzle of the present invention, the shape of the opening at the inlet of the injection hole is as follows:
It has a shape that is easy to flow fuel from a predetermined direction to the injection hole and is asymmetric with respect to the axial direction of the injection hole, and the predetermined direction is formed so as to be different from the fuel flow direction. For this reason, the flow rate of the fuel from the side where the fuel easily flows at the injection hole inlet portion can be made larger than the flow amount of the fuel from the side where the fuel flow is difficult at the injection hole inlet portion, and the fuel flow swirls into the injection hole. It is possible to generate a flow. Since the swirling flow has momentum at the nozzle hole outlet in the tangential direction of the nozzle hole diameter, the spray angle can be increased. Thus, it is possible to promote the atomization of the fuel with a simple configuration without increasing the number of parts. Therefore, NOx, black smoke, and HC can be reduced, and fuel efficiency and output can be improved. Furthermore, since it is not necessary to provide a sliding portion for generating a swirling flow in the valve needle, seizure of the valve needle can be prevented, and the durability of the fuel injection nozzle is improved.

According to the fuel injection nozzle of the second aspect of the present invention, the opening shape of the injection hole inlet is formed in a circle or an ellipse eccentric with respect to the axis of the injection hole. A swirling flow of the fuel flow can be easily generated in the injection hole. According to the fuel injection nozzle according to the third aspect of the present invention, since the opening shape of the injection hole inlet portion is formed asymmetrically with respect to the generatrix of the valve seat portion, it can be easily formed in the injection hole with a simple configuration. A swirling flow of the fuel flow can be generated. According to the fuel injection nozzle of the fourth aspect of the present invention, the injection hole inlet portion has a simple configuration because the inner wall on the side where fuel easily flows has a larger radius than the inner wall on the side where fuel does not easily flow. A swirling flow of the fuel flow can be easily generated in the injection hole.

According to the fuel injection nozzle of the fifth aspect of the present invention, the distance between the valve needle and the inlet of the injection hole changes in accordance with the lift amount of the valve needle. Since the first region has a second region that does not change regardless of the amount, the distance between the valve needle and the inlet of the injection hole changes in accordance with the lift of the valve needle. The component of the fuel flow flowing around the circumference is adjusted, and the ratio of the component of the fuel flow along the seat surface of the nozzle body to the component of the fuel flow from the axis of the injection hole is adjusted. Then, the spray angle of the fuel is adjusted according to the lift of the valve needle. In the second region, the fuel spray angle is maintained at a predetermined value.
Therefore, it is possible to obtain a desired spray angle and a spray reaching distance in accordance with the load state of the engine, to promote the atomization of fuel with a simple configuration without increasing the number of parts, and to control the spray characteristics. It can be carried out. As described above, the fuel consumption can be reduced, the exhaust emission can be improved, and the stable drivability of the engine can be obtained. Further, by arbitrarily setting the first region and the second region, the spray angle can be arbitrarily selected from the early stage to the late stage of the injection. Therefore, it is possible to easily cope with various types of engine fuel injection valves.

According to the fuel injection nozzle of the present invention, the distance between the valve needle and the inlet of the injection hole is a predetermined value set when a swirl flow is generated in the fuel flow in the injection hole. Therefore, when the distance between the valve needle and the inlet of the injection hole is at the above-mentioned predetermined value, by generating a swirling flow of the fuel flow in the injection hole, the engine speed is reduced.
At the time of medium to low load, an optimal state in which the combustible air-fuel mixture is stratified by atomization of the mixture of fuel and air is formed, and the fuel consumption rate, exhaust emission, and noise can be improved.

According to the fuel injection nozzle of the present invention, the distance between the valve needle and the inlet of the injection hole is such that a swirl flow is not generated in the fuel flow in the injection hole when the valve needle is fully lifted. Since the swirling flow is not generated at the maximum lift of the valve needle, a swirl flow is not generated in the fuel flow in the injection hole, and the spray angle can be reduced. Therefore, when the engine is operated under a high load, the reach of the spray is increased, and a high diffusion spray is formed, so that the output can be improved.

According to a method of processing a fuel injection nozzle according to claim 8 of the present invention, there is provided a method of processing a fuel injection nozzle according to any one of claims 1 to 5, wherein A swirl flow forming unit that generates a swirl flow is provided, and the inner wall of the inlet of the injection hole is machined using a machining needle that can be inserted into the nozzle body. For this reason, the fluid for fluid grinding is supplied from the upstream of the swirl flow forming section, and a circumferential component is given to the fluid flow to generate a swirl flow and flow out of the orifice, so that the swirl flow upstream of the orifice inlet is provided. The side inner wall is ground more than the downstream inner wall. Therefore, the shape of the injection hole inlet portion can be easily formed into an asymmetric shape in which fuel easily flows into the injection hole from a predetermined direction.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; (First Embodiment) FIGS. 1 to 13 show a first embodiment in which the fuel injection nozzle of the present invention is applied to a nozzle portion of a fuel injection valve for a diesel engine.

A fuel injection valve 100 shown in FIG. 2 is a fuel injection valve that injects fuel into a combustion chamber of a diesel engine (not shown) in a stepwise manner. Is driven by high-pressure fuel from a high-pressure pump calculated and controlled by the ECU in accordance with the input of the temperature, pressure, and the like. The fuel injection valve 100 includes a first spring 115 as a first urging means for controlling the needle lift, a second spring 116 as a second urging means, an armature chamber 134, and a change in the spray angle or the opening injection. The nozzle unit 1 is configured as a fuel injection nozzle whose hole can be changed.

The fuel injection valve 100 has a structure in which the nozzle portion 1 is fastened to a holder 111 by a retaining nut 114. The needle 2 is slidably fitted into the inner diameter portion 34 of the nozzle body 3 of the nozzle portion 1. The needle 2 as a valve needle is pressed by a first spring 115 via a piston 120 against a seat surface 32 as a valve seat of the nozzle body 3. The first spring 115
It is fitted into a spring chamber 115a provided inside the core 133 of the magnetic drive unit 130. As shown in FIGS. 1 and 2, when the needle 2 is seated on the seat surface 32,
The shoulder portion 25 of the needle 2 is recessed from the upper end surface of the nozzle body 3 by a distance h1, that is, by the first lift amount h1 of the needle 2.

The holder 111 includes a magnetic drive unit 130.
Are fastened with a nut 112. Magnetic drive unit 130
Are a first spring 115, a piston 120, a coil 131,
It is composed of an armature 132, a core 133, a body 135, and a plate 136 having a fuel passage 137. The piston 120 is slidably fitted into the inner diameter portion 113 of the holder 111, and an armature 132 is provided on an upper portion. The piston 120 has the shoulder 125 on the plate 1
36 to make the maximum lift amount (h1 + h
It is specified to keep in 2). Therefore, the maximum lift that the needle 2 can lift upward is (h1 + h2)
Becomes The coil 131 is wound around the core 133, and forms a magnetic circuit with the core 133, the armature 132, and the body 135 when an external current is supplied to the coil 131, that is, when the coil 131 is energized. Also, as shown in FIG.
Faces the core 133 while keeping a distance obtained by adding the final gap to the maximum lift amount (h1 + h2) of the needle 2. The fuel passage 137 formed in the plate 136 is open to the above-described armature chamber 134.

As shown in FIG. 3, the piston 120 and the needle 2 have a spherical portion 149 of the needle held by a spherical portion 126 and a conical portion 127 of the piston 120 and a spherical portion 149.
Are connected to each other so as to be rotatable about the center of the ball.
As shown in FIG. 2, the second spring 116 is inserted into a spring chamber 116 a provided in the inner diameter portion of the holder 111 and presses the spring seat 4 against the nozzle body 3. Second spring 116
Acts on the shoulder 25 of the needle 2 when the needle 2 is lifted by the first lift amount h1.

Inner diameter portion 113 of holder 111 and piston 1
The high-pressure flow path 163 between the high-pressure fuel tank and the fuel tank 160 communicates with a common rail (not shown) storing high-pressure fuel through a filter 161 and a high-pressure passage 162 provided in the fuel connector 160. The fuel passage 163 communicates with the armature chamber 134 via the multifaceted cut portion 117 of the piston 120 and the fuel passage 137, and the spring chamber 116
a, the oil sump chamber 35 and the needle 2 through the multifaceted cut portion 24 formed in the guide portion 23 of the needle 2
It communicates with the seat 21 of the needle 2 via a fuel passage 36 between the nozzle body 3 and the inner diameter portion 33 of the nozzle body 3. Accordingly, the high-pressure fuel supplied from the high-pressure pump (not shown) is supplied to the common rail, the high-pressure flow path 163 and the fuel passage 3.
6, and supplied to the armature chamber 134 via the fuel passage 137.

Next, the structure of the nozzle unit 1 will be described with reference to FIGS. FIG. 4 shows the needle 2
5 shows a closed state in which the seat 21 as a contact portion of the nozzle body 3 is seated on the seat surface 31 of the nozzle body 3. FIG. FIG. 6 shows a state in which the needle 2 has been lifted by the first lift amount h1.

The nozzle unit 1 shown in FIGS. 4, 5 and 6
Is composed of a nozzle body 3 and a needle 2 housed inside the nozzle body 2 so as to be reciprocally slidable in the axial direction. The needle 2 is provided on the seat surface 32 of the nozzle body 3.
And a conical portion 25, a cylindrical portion 26, and a conical portion 27 formed downstream of the sheet 21. The seat 21 of the needle 2 is closed by a first spring 115 shown in FIG. 2 and abuts against a seat surface 32 of the nozzle body 3.
It is pushed up against 15 and opens. The wall surfaces of the conical portion 25 and the conical portion 27 have a larger cone angle than the seat surface 32 of the nozzle body 3 and constitute a flow path. As shown in FIGS. 5 and 6, the surface facing the injection hole 31 moves to the wall surface of the conical portion 25, the wall surface of the cylindrical portion 26, and the wall surface of the conical portion 27 according to the lift of the needle 2.

The inlet 31a of the injection hole 31 formed on the downstream side of the sheet surface 32 of the nozzle body 3 is
Is formed in an asymmetric shape in which fuel easily flows into the injection hole 31 from a predetermined direction inclined with respect to the axis of the seat surface 32.
The shape is asymmetrical with respect to the generating line. That is, as shown in FIGS. 7 and 8, the opening shape of the inlet 31 a of the injection hole 31 is asymmetric with respect to the axial direction of the injection hole 31.
The predetermined direction is formed so as to be different from the direction of the fuel flow. In addition, the opening shape of the inlet 31a of the injection hole 31 is formed in an elliptical shape eccentric with respect to the axis of the injection hole 31, so that the upstream inner wall 31b where the fuel easily flows is lower than the downstream inner wall 31c where the fuel hardly flows. Are also formed with a large radius. Thereby, the flow rate of the fuel from the side where the fuel easily flows in the inlet portion 31a can be made larger than the flow rate of the fuel from the side where the flow of the fuel is difficult, so that the fuel passing through the injection hole 31 exerts a circumferential turning force. It is possible to add Here, the upstream side inner wall 31b and the downstream side inner wall 31c of the inlet 31a constitute a fuel flow path.

Next, a method of processing the nozzle portion 1 will be described with reference to FIGS. 9, 10 and 11. FIG. Note that FIG.
Shows a state in which the swirling flow forming portion 11 of the processing needle 10 is fitted into the inner diameter portion 33 of the nozzle body 3. As shown in FIG. 9, the processing needle 10 includes a swirling flow forming unit 11, and the swirling flow forming unit 11 has an oblique groove 12 formed therein. On the downstream side of the swirling flow forming section 11, a swirling chamber 14 is formed between the seat surface 32 of the nozzle body 3 and the wall surface of the conical section 13. The seat portion 15 of the processing needle 10 is attached to the seat surface 32 of the nozzle body 3.
At the downstream side of the injection hole 31. When the grinding fluid mixed with the abrasive grains is supplied from the upstream side of the swirling flow forming unit 11,
The grinding fluid is given a velocity component in the circumferential direction by the oblique groove 12, and becomes a swirling flow in the swirling chamber 14 and flows toward the injection hole 31. As shown in FIG. 10, abrasive grains flow into the inlet 31 a of the injection hole 31 at an angle inclined with respect to the axis of the nozzle body 3, and are injected from the upstream inner wall 31 b of the inlet 31 a on the swirl flow inflow side. It flows into the hole 31 in a larger amount than from the downstream inner wall 31. As a result, as shown in FIG. 11, the upstream side inner wall 31b of the inlet portion 31a is ground more than the downstream side inner wall 31, the radius of the upstream side inner wall 31b becomes larger than the radius of the downstream side inner wall 31, and the injection hole 31 The inlet portion 31a is formed in an asymmetric shape into which fuel easily flows.

Next, regarding the operation of the fuel injection valve 100,
This will be described with reference to FIGS. Note that the comparative example shown by a dotted line in FIGS. 12 and 13 is a cylindrical portion 26 of the needle 2 of the first embodiment, as shown by a dotted line in FIGS.
And the conical portion 27 is eliminated.

(1) A predetermined amount of fuel is pressure-fed from a high-pressure pump via a common rail at a predetermined time, and the high-pressure fuel is supplied to the fuel connector 160 via a fuel pipe. This high-pressure fuel is supplied into the nozzle unit 1 through the high-pressure passage 162 and the high-pressure passage 163, and is filled up to the sheet 21 of the needle 2 through the multifaceted cut portion 24 and the fuel passage 36. At this time, the fuel pressure acts on the area of the seat 21 and the nozzle 21
Is applied to the sheet surface 32. Further, the set load of the first spring 115 is applied, and the needle 2 is pushed down in FIG.

(2) When a coil 131 of the magnetic drive unit 130 is supplied with a first current value by the ECU (not shown),
The suction force that overcomes the hydraulic pressure applied to the seat 21 to the needle 2 and the set load of the first spring 115 is applied to the core 133.
In the magnetic circuit between the armature 132 and the armature 132. As a result, the armature 132 rises integrally with the piston 120 and the needle 2, and the seat 21 is separated from the seat surface 32 of the nozzle body 3 to supply fuel to the injection hole 31.
At the first current value at this time, the second spring 1 acting when the shoulder 25 of the needle 2 comes into contact with the second spring 116
The needle 2 stops at the first lift h1 because a magnetic force sufficient to attract the armature 132 by overcoming the set load of 16 is not generated. As shown in FIGS. 5 and 6, as the needle 2 rises, the wall surface of the needle 2 facing the inlet 31a of the injection hole 31 moves, and at the first lift h1, the inlet 31a of the injection hole 31 becomes a cylindrical portion. 26 wall surface. The distances L1 and L3 between the wall surfaces of the conical portions 25 and 27 and the inlet 31a of the injection hole 31 change according to the lift of the needle 2 (first region). However, cylindrical part 2
The distance L2 between the wall surface of No. 6 and the inlet 31a of the injection hole 31 does not change due to the lift of the needle 2 (second region). This distance L2 corresponds to the time when the fuel flowing into the injection hole 31 is
Is set to a small value so that the flow along the sheet surface 32 becomes the main flow. Here, FIG. 5 corresponds to FIG. 12 and FIG.
3 shows a state in which the needle lift is between (0-a), and FIG. 6 shows a state in which the needle lift shown in FIGS. 12 and 13 is h1. When the needle lift is h1, as shown in FIG. 7, the fuel linearly flows from the upstream into the injection hole 31 in parallel with the axial direction of the nozzle body 3. At this time, the inlet 31a of the injection hole 31 is formed such that the upstream inner wall 31b has a larger radius than the downstream inner wall 31c,
Since the opening of the inlet 31a is formed in an elliptical shape eccentric with respect to the axis of the injection hole 31, the flow rate of the fuel from the side of the inlet 31a where the fuel easily flows is reduced. And the swirling flow is generated in the fuel passing through the injection hole 31. This swirling flow reduces the velocity coefficient of the flow in the injection hole 31, and as a result, as shown in FIG. 12, keeps the flow coefficient small. However, since the swirling flow has momentum at the outlet of the injection hole 31 in the tangential direction of the injection hole diameter, the spray angle θ increases as shown in FIGS. 8 and 13. Thus, the first lift h1 of the needle 2
At times, an injection spray characteristic with a low injection rate and a large spray angle θ is obtained. Therefore, the first lift h1 is used when the engine is at a low speed and a medium to low load, and forms an optimal state in which the combustible air-fuel mixture is stratified by atomization of the mixture of the fuel and the air. Improve emissions and noise. On the other hand, in the comparative examples shown by dotted lines in FIGS. 12 and 13, when the needle lift is h1, the distance between the wall surface of the needle and the injection hole inlet portion greatly varies depending on h1, so that the predetermined value can be maintained. Therefore, it is difficult to control the spray characteristics when the engine is at a low speed and a low load.

(3) When a high voltage is applied to the coil 131 of the magnetic drive unit 130 so that the second current value flows, the force of the core 133 to attract the armature 132 is applied to the second spring 11.
6, the needle 2 is further pulled up, and the needle 2 is raised until the shoulder 125 of the 120 comes into contact with the plate 136, so that the maximum lift amount (h1 + h2) is reached. As shown in FIGS. 12 and 13, the needle lift changes from h1 to b, c, (h1 + h2). Second
In the lift (h1 + h2), the inlet portion 31a of the injection hole 31 faces the wall surface of the conical portion 27 of the needle 2, and the distance between the inlet portion 31a of the injection hole 31 and the wall surface of the conical portion 27 is equal to the cylindrical portion 26.
Is smaller than the minimum distance L2. The distance L3 when the needle lift is (h1 + h2) is
A sufficient distance is formed upstream of the inlet 31a of the
1 flows into the seat surface 32 of the nozzle body 3.
The flow from on the axis of the injection hole 31 becomes the main flow rather than the flow along. As a result, the swirling flow along the injection hole wall surface is reduced in the injection hole 31 and the axial flow becomes dominant, so that the spray angle decreases, the flow coefficient increases, and the injection rate increases. Therefore, the spread distance of the spray is increased to form a high-diffusion spray, thereby improving the combustion under high load operation and improving the output.

(4) When the power supply to the coil 131 is stopped, the magnetic force disappears, the core 133 cannot continue to suck the armature 132, and the piston 120 is attached with the first and second springs 115 and 116. The needle 21 is moved downward by the force, and the seat 21 of the needle 2 is seated on the seat surface 32 of the nozzle body 3 to terminate the fuel injection.

In the above-described first embodiment of the present invention, the fuel injection valve 100 can control the valve lift in two stages of the first lift h1 and the second lift (h1 + h2).
, The inlet portion 31a of the injection hole 31 is
Is formed in an asymmetric shape in which fuel easily flows into the injection hole 31 from a predetermined direction inclined with respect to the axis of the seat surface 32.
The opening shape of the inlet 31a of the injection hole 31 is asymmetrical with respect to the axial direction of the injection hole 31, and the predetermined direction is different from the direction of the fuel flow. It is formed to be. In addition, the opening shape of the inlet 31a of the injection hole 31 is formed in an elliptical shape eccentric with respect to the axis of the injection hole 31, so that the upstream inner wall 31b where the fuel easily flows is lower than the downstream inner wall 31c where the fuel hardly flows. Are also formed with a large radius. For this reason, the flow rate of the fuel from the upstream inlet of the injection hole 31 can be made larger than the flow rate of the fuel from the downstream inlet, and a swirling flow of the fuel flow can be generated in the injection hole 31. . Since the swirling flow has a momentum at the exit of the injection hole 31 in the tangential direction of the injection hole diameter, the spray angle θ can be increased, so that the fuel atomization can be promoted with a simple configuration without increasing the number of parts. Can be planned. Therefore, NOx, black smoke, and HC can be reduced, and fuel efficiency and output can be improved. In addition, since it is not necessary to provide a sliding portion for generating a swirling flow in the needle 2, seizure of the needle 2 can be prevented,
The durability of the nozzle unit 1 is improved. Further, since the needle 2 is closed when the sac provided at the tip of the nozzle body 3 is closed, it is possible to prevent the occurrence of deposits due to fuel after the end of the injection.

In the first embodiment, the needle 2
A first region in which the distance between the wall surface of the nozzle and the inlet portion 31a of the injection hole 31 changes according to the lift amount of the needle 2, and a second region in which the distance does not change regardless of the lift amount of the needle 2. Therefore, in the first region, the distance between the wall surface of the needle 2 and the inlet 31a of the injection hole 31 changes according to the lift of the needle 2, and the component of the fuel flow flowing through the inner periphery of the nozzle body 3 is adjusted. The ratio of the component of the fuel flow along the seat surface 32 of the nozzle body 3 to the component of the fuel flow from the axis of the injection hole 31 is adjusted. Then, the spray angle of the fuel is adjusted according to the lift of the valve needle. In the second region, the fuel spray angle is maintained at a predetermined value. Therefore, it is possible to obtain a desired spray angle and a spray reaching distance in accordance with the load state of the engine, to promote the atomization of fuel with a simple configuration without increasing the number of parts, and to control the spray characteristics. It can be carried out. As described above, the fuel consumption can be reduced, the exhaust emission can be improved, and the stable drivability of the engine can be obtained. Further, by arbitrarily setting the first region and the second region, the spray angle can be arbitrarily selected from the early stage to the late stage of the injection. Therefore, it is possible to easily cope with various types of engine fuel injection valves.

Further, in the first embodiment, the distance between the wall surface of the needle 2 and the inlet 31a of the injection hole 31 is
Needle lift amount h in which swirling flow is generated in fuel flow in 1
When the needle lift amount h1 is L2, the distance between the wall surface of the cylindrical portion 26 of the needle 2 and the inlet 31a of the injection hole 31 is L2. By generating a swirling flow of the fuel flow inside the engine, at the time of medium to low speed and medium to low load of the engine, the optimal state is obtained in which the combustible air-fuel mixture is stratified by atomization of the mixture of fuel and air. It can improve consumption rate, exhaust emissions and noise.

Further, in the first embodiment, the distance between the wall surface of the needle 2 and the inlet 31a of the injection hole 31 is such that the injection hole 31 is at the maximum needle lift (h1 + h2).
Since the swirl flow is formed so large that the swirl flow is not generated in the fuel flow therein, the swirl flow is not generated in the fuel flow in the injection hole 31 at the time of the maximum needle lift (h1 + h2), and the spray angle can be reduced. Therefore, when the engine is operated under a high load, the reach of the spray is increased, and a high diffusion spray is formed, so that the output can be improved.

Further, in the first embodiment, a swirl flow forming unit 11 for generating a swirl flow in the flow of the grinding fluid is provided, and the injection hole 31 is formed by using the machining needle 10 which can be inserted into the nozzle body 3. In order to process the inner wall of the entrance part 31a,
The grinding fluid is supplied from the upstream of the swirl flow forming section 11, and a circumferential component is given to the fluid flow to generate a swirl flow and flow out from the injection hole 31, so that the upstream inner wall 31 b of the inlet 31 a of the injection hole 31 is formed. Is ground more than the downstream inner wall 31c. Therefore, the inlet portion 31a can be easily formed in an asymmetric shape in which fuel easily flows into the injection hole 31.

In the first embodiment, a greater effect can be obtained by combining with a needle having a swirl chamber for generating a swirling flow in the fuel. In this case, the opening shape of the injection hole inlet portion is made more effective by forming an asymmetric shape in which fuel can easily flow to the injection hole from a predetermined direction different from the flow direction of the swirling flow. In the first embodiment, the fuel injection nozzle of the present invention is applied to the nozzle unit 1 of the fuel injection valve 100 that controls the valve lift in two stages of the first lift h1 and the second lift (h1 + h2). Needless to say, the present invention can be applied to a nozzle portion of a fuel injection valve that controls the valve lift to only one of the first lift and the second lift.

In the first embodiment, the inlet portion 31a of the injection hole 31 is formed on the conical surface on the downstream side of the seat surface 32 of the nozzle body 3.
However, in the present invention, the inlet of the injection hole may be formed on the inner wall surface of the sack at the tip of the nozzle body. Furthermore, in the first embodiment, the fuel injection nozzle of the present invention is applied to the nozzle portion 1 of the fuel injection valve 100 for a diesel engine, but the present invention is applied to the nozzle portion of a fuel injection valve for a gasoline engine. Is also good.

(Second Embodiment) A method of processing a nozzle portion according to a second embodiment will be described with reference to FIG. Components that are substantially the same as those in the method for processing the nozzle portion 1 of the first embodiment shown in FIG. FIG. 14 shows a state in which the swirling flow forming portion 51 of the processing needle 50 is fitted into the inner diameter portion 33 of the nozzle body 3.

As shown in FIG.
Is provided with a swirl flow forming unit 51, and the swirl flow forming unit 5
A plurality of outflow holes 52 communicating with the outer wall are formed on the bottom surface of one inner diameter portion 51a. On the downstream side of the swirling flow forming section 51, a swirling chamber 54 is formed between the seat surface 32 of the nozzle body 3 and the wall surface of the conical section 53. The seat portion 55 of the processing needle 50 is attached to the seat surface 32 of the nozzle body 3.
At the downstream side of the injection hole 31. When the grinding fluid mixed with the abrasive grains is supplied to the inner diameter portion 51 a of the swirling flow forming section 51, the grinding fluid is given a circumferential velocity component at the outflow hole 52, and becomes a swirling flow at the swirling chamber 54 toward the injection hole 31. It flows. Then, abrasive grains flow into the inlet 31 a of the injection hole 31 at an angle inclined with respect to the axis of the nozzle body 3,
Similarly to the first embodiment, the upstream inner wall of the inlet 31a of the injection hole 31 is ground more than the downstream inner wall, and the inlet 31a is formed in an asymmetric shape in which fuel easily flows into the injection hole 31.

In the second embodiment, since the grinding fluid mixed with the abrasive grains does not flow out to the outer wall of the swirling flow forming portion 51 of the machining needle 50, the abrasive grains after the grinding process are washed with the sheet of the nozzle body 3. The cleaning step can be simplified and the number of processing steps can be reduced. Further, since the processing of the outflow hole 52 of the processing needle 50 is easier than the processing of the oblique groove 12 of the processing needle 10 of the first embodiment shown in FIG.
The increase in the number of processing steps a can be offset, and the processing needle 50 can be processed at low cost.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a first embodiment in which the fuel injection nozzle of the present invention is applied to a nozzle portion of a fuel injection valve for a diesel engine.

FIG. 3 is an enlarged view of a part III in FIG. 2;

FIG. 4 is a longitudinal sectional view showing a main part of the fuel injection nozzle according to the first embodiment of the present invention.

FIG. 5 is a longitudinal sectional view illustrating the operation of the fuel injection nozzle according to the first embodiment of the present invention.

FIG. 6 is a longitudinal sectional view for explaining the operation of the fuel injection nozzle according to the first embodiment of the present invention.

FIG. 7 is a view in the direction of arrows VII in FIG. 5;

8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a longitudinal sectional view for explaining a method of processing the fuel injection nozzle according to the first embodiment of the present invention.

FIG. 10 is a view in the direction of the arrow X in FIG. 9;

11 is a sectional view taken along line XI-XI in FIG.

FIG. 12 is a characteristic diagram showing a relationship between a needle lift of a fuel injection nozzle, an injection hole upstream flow path area, and a flow coefficient according to the first embodiment of the present invention.

FIG. 13 is a characteristic diagram showing a relationship between a needle lift of a fuel injection nozzle and a spray angle according to the first embodiment of the present invention.

FIG. 14 is a longitudinal sectional view illustrating a method of processing a fuel injection nozzle according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle part (fuel injection nozzle) 2 Needle (valve needle) 3 Nozzle body 10 Processing needle 11 Swirl flow forming part 12 Slant groove 14 Swirl chamber 21 Sheet (contact part) 31 Injection hole 31a Inlet part 31b Upstream inner wall 31c Downstream inner wall 32 Seat surface (valve seat) 50 Processing needle 51 Swirling flow forming unit 52 Outflow hole 54 Swirling chamber 100 Fuel injection valve

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenji Date 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside Denso Corporation (72) Inventor Eiji Ito 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Denso Corporation F term (reference) 3G066 AA07 AB02 BA03 BA11 BA14 BA16 BA25 BA26 BA55 BA61 CC14 CC27 CC43 CE22

Claims (8)

[Claims] A nozzle body provided with a valve seat upstream of an injection hole; and a contact portion supported reciprocally slidable by the nozzle body and seatable on the valve seat. A valve needle that separates from the valve seat and seats and shuts off fuel by sitting on the valve seat, wherein the opening shape of the inlet of the injection hole is: It is easy to flow fuel from a predetermined direction to the injection hole, and has an asymmetric shape with respect to the axial direction of the injection hole, and the predetermined direction is formed to be different from the direction of fuel flow. Fuel injection nozzle. 2. The fuel injection nozzle according to claim 1, wherein the opening of the inlet portion is formed in a circular or elliptical shape eccentric to the axis of the injection hole. 3. The fuel injection nozzle according to claim 1, wherein the shape of the opening of the inlet is asymmetric with respect to the generatrix of the valve seat. 4. The fuel injection nozzle according to claim 1, wherein the inlet has an inner wall on a side where fuel easily flows has a larger radius than an inner wall on a side where fuel does not easily flow. 5. A distance between the valve needle and an inlet of the injection hole, wherein the first region changes according to the lift amount of the valve needle, and a second region which does not change regardless of the lift amount of the valve needle. The fuel injection nozzle according to any one of claims 1 to 4, further comprising: 6. A distance between the valve needle and an inlet of the injection hole is maintained at a predetermined value when a swirl flow is generated in a fuel flow in the injection hole. The fuel injection nozzle according to claim 1. 7. The distance between the valve needle and the inlet of the injection hole is formed so large that a swirl flow is not generated in the fuel flow in the injection hole during the maximum lift of the valve needle. 7. The method according to claim 1, wherein
A fuel injection nozzle according to any one of the preceding claims. 8. A method for processing a fuel injection nozzle according to claim 1, further comprising: a swirl flow forming unit that generates a swirl flow in a fluid flow for fluid grinding, wherein the nozzle body is provided. Processing the inner wall of the inlet of the injection hole using a processing needle that can be inserted into the fuel injection nozzle.