WO2005050005A1

WO2005050005A1 - Fuel injection valve

Info

Publication number: WO2005050005A1
Application number: PCT/JP2003/014684
Authority: WO
Inventors: Noriyuki Maekawa; Motoyuki Abe; Yoshio Okamoto; Masaya Horino; Masatoshi Kanamaru; Yoshiyuki Tanabe; Takeshi Harada; Kiyotaka Ogura
Original assignee: Hitachi, Ltd.
Priority date: 2003-11-18
Filing date: 2003-11-18
Publication date: 2005-06-02
Also published as: JPWO2005050005A1; JP4283275B2; AU2003280861A1

Abstract

A revolvable element (12) made of single-crystal silicon is held in a revolvable element holding section (22) and is fixed between a nozzle (11) and an orifice plate (1) through an elastic member (21). A central flow channel in the revolvable element (12) is provided with a ridge to narrow the annular clearance between the outer diameter of a revolvable element (7) and the inner diameter of the revolvable element. The flow rate of the fuel flowing through the annular clearance is suppressed and a strong revolving force is imparted to the fuel.

Description

Specification

Fuel injection valve technical field

The present invention relates to a fuel injection valve, and more particularly to a fuel injection valve mounted on an internal combustion engine for supplying fuel. The present invention relates to a fuel injection valve for an internal combustion engine having a swirl element (swirler structure) formed of a brittle material such as single crystal silicon. Background art

In general, a fuel injection valve for an internal combustion engine includes a fuel injection hole, a valve seat disposed near the fuel injection hole, a swirling element (swirler structure) for applying a swirling force to the supplied fuel, and a valve. A valve body slidably supported in the axial direction at a position facing the seat, a driving force generating unit for driving the valve body in the axial direction, and a spring for pressing the valve body against the valve seat are provided. .

The fuel supplied to the fuel injection valve passes through the fuel passage inside the fuel injection valve and is guided to the vicinity of the fuel injection hole. When the valve is pressed against the valve seat by the spring pressing force, fuel is not injected because the fuel injection hole is closed. When the driving force generating section generates a force on the valve body in a direction opposite to the pressing force of the spring, the valve body is separated from the valve seat. In this state, the fuel injection hole is opened, so that the fuel is injected. At this time, the swirling force is applied to the fuel by the action of the fuel swirl flow path provided in the swirl element arranged near the fuel injection hole. The fuel injected from the fuel injection hole with the swirling force forms a thin liquid film, which can be broken up into small droplets.

In order to stabilize combustion of the internal combustion engine or reduce harmful components contained in exhaust gas discharged from the internal combustion engine, a fuel injection valve capable of supplying a fuel spray having a small particle size is required.

Patent documents (FIGS. 2, 4, 5, and 7 of Japanese Patent Application Laid-Open No. 10-122,955) are cited as prior art for this purpose. In this patent document, the orientation of the fuel injection valve is described. The swirl chamber and the orifice are formed in the orifice plate made of single crystal silicon by using a single crystal silicon as the plate.

In the above prior art, a single crystal silicon orifice plate of a fuel injection valve is provided with a swirling chamber as a concave portion and an orifice as a through hole.

However, in the above prior art, no consideration is given to the shape of the orifice, which is a through-hole, and the molding method.

In the orifice plate of the fuel injection valve according to the prior art, the swirl chamber is formed of single-crystal silicon, but only a small-diameter orifice is provided at the center of the swirl chamber. Since the swirl chamber is provided downstream of the valve seat, it does not have a configuration in which the valve element is inserted into a single-crystal silicon orifice plate.

Therefore, in order to improve the atomization performance of a fuel injection valve of the type in which the swirling element is located upstream of the valve seat, that is, the upstream swirling type fuel injection valve, the swirling element is formed of a brittle material such as single crystal silicon and has a strong swirling force. To form a swirl channel, the following issues must be solved.

The upstream swirl type fuel injection valve has a configuration in which a valve body is inserted into a through hole provided in the center of the swirl element. Therefore, a central flow path (through hole) for inserting the valve element is required in the center of the turning element. It is necessary to provide a slight gap between the central channel formed in the swirl element and the outer peripheral portion of the valve element, and this gap needs to be as small as possible.

If the gap is large, the flow rate of the fuel passing through the gap, that is, the fuel that does not pass through the swirl flow path of the swirl element and does not receive a swirling force increases, which may deteriorate the atomization characteristics of the fuel injection valve. Because there is. Therefore, when the swirling element of the fuel injection valve is formed of single crystal silicon, it is an issue to reduce the flow rate of the fuel that does not exert swirling force.

In the case of an upstream-swirl type fuel injection valve, the inner wall of the central passage of the swirling element is often used as a sliding guide for the valve element. When the swivel element is formed of single crystal silicon, there is a possibility that the inner wall of the central flow path of the swivel element cannot be used as a sliding guide due to durability problems. Therefore, the swirl element of the fuel injection valve is a single crystal silicon In the case of using a brittle material such as a rotating element, it is a problem to provide an appropriate sliding guide on the inner side wall of the central flow path of the turning element.

Furthermore, when the swivel element is formed from a brittle material such as single crystal silicon, it is an issue to prevent the swivel element from being damaged by the stress applied during assembly.

Furthermore, when the swirling element is formed only of single-crystal silicon, the structure is such that the fuel directly contacts the silicon. For this reason, if a small amount of silicon dissolves into the fuel, the silicon may adhere to the auxiliary components of the internal combustion engine and deteriorate the performance of the auxiliary components. Therefore, it is an issue to prevent the fuel from directly contacting the single crystal silicon swirl element. Disclosure of the invention

An object of the present invention is to solve the above-mentioned problems, to enable mounting of a swirl element made of a brittle material, to improve the degree of freedom in shaping the swirl flow path, and to obtain a fuel injection valve having good atomization characteristics. It is in.

Therefore, in the present invention, the fuel injection valve includes a swirl element for imparting a swirl force to fuel, and the swirl element is formed of a brittle material. It is formed by a combination of a step of forming a central flow path from the upstream side and a step of forming a central flow path from the downstream side of the swirling element.

Further, according to the present invention, the fuel injection valve includes a swirl element that applies a swirl force to the fuel, and the swirl element is formed of a brittle material. A convex portion is formed substantially at the center.

Further, according to the present invention, there is provided a fuel injection valve comprising a swirl element for imparting a swirl force to fuel, wherein the swirl element is formed of a brittle material, and has a substantially circular central flow path at the center of the swirl element. The flow path diameter of the central flow path on the surface side of the swirl element having the swirl flow path is smaller than the flow path diameter of the swirl element on the side opposite to the surface of the swirl element having the swirl flow path. Further, according to the present invention, in a fuel injection valve provided with a swirl element for applying a swirl force to fuel, a side wall of a swirl flow path of the swirl element and a side wall of a central flow path provided at an inner diameter portion of the swirl element The angle of the tip of the acute angle portion formed by the above is set to be in the range of 0 to 0.01 mm.

Further, according to the present invention, there is provided a fuel injection valve including a swirl element for imparting a swirl force to fuel, and a valve body for controlling a fuel injection amount. A turning element holding member is provided, and the valve element is slidably guided at an inner diameter portion of the turning element holding member.

Further, according to the present invention, in a fuel injection valve provided with a swirling element for applying a swirling force to fuel, a sliding member for slidingly guiding the valve element is provided at an inner diameter portion of the swirling element.

Further, according to the present invention, in a fuel injection valve provided with a swirling element for applying a swirling force to fuel, an end surface of the swirling element on a side having a swirling flow path, and a fixing member in contact with the swirling element, At least one of the end faces that are in contact with the end face of the turning element, in the vicinity of the central flow path provided in the inner diameter portion of the turning element, a tape for preventing the turning element from contacting with the fixed member. One or a step is provided. Further, according to the present invention, in the fuel injection valve including a swirl element that applies a swirl force to the fuel, and the swirl element is formed of single-crystal silicon, the single-crystal silicon that is a base material of the swirl element directly contacts the fuel. In order to prevent this, a surface layer is provided on the surface of the turning element.

Further, in the present invention, the surface layer is a silicon oxide film. Brief Description of Drawings

FIG. 1 is a sectional view showing an embodiment of the fuel injection valve of the present invention. FIG. 2A is a plan view showing a swirl element of the fuel injection valve of the present invention. FIG. 2B is a cross-sectional view showing the swirl element of the fuel injection valve of the present invention. FIG. 3 is an enlarged partial cross-sectional view of the structure near the swirl element of the fuel injection valve of the present invention. FIG. 4 is an enlarged sectional view of the swirling element and the rod of the fuel injection valve of the present invention. FIG. 5A shows the fuel injection valve of the present invention. It is a top view which shows a rotation element holding member. FIG. 5B is a cross-sectional view showing a turning element holding member of the fuel injection valve of the present invention. FIG. 6 is an enlarged sectional view of the swirling element and the rod of the fuel injection valve of the present invention. FIG. 7 is a cross-sectional view showing the swirl element of the fuel injection valve of the present invention and its surface layer. FIG. 8 is a plan view showing a swirl element of the fuel injection valve of the present invention and a sliding member provided on an inner peripheral portion of the swirl element. FIG. 9A is a plan view showing a swirl element according to another embodiment of the fuel injection valve of the present invention. FIG. 9B is a sectional view showing a swirl element according to another embodiment of the fuel injection valve of the present invention. FIG. 9C is a rear view showing a swirl element according to another embodiment of the fuel injection valve of the present invention. FIG. 10A is a plan view showing the nozzle of the fuel injection valve of the present invention. FIG. 10B is a sectional view showing the nozzle of the fuel injection valve of the present invention. FIG. 11A is a plan view showing a swirl element (swirler structure) of another embodiment of the fuel injection valve of the present invention. FIG. 11B is a cross-sectional view showing a swirling element (swirler structure) of another embodiment of the fuel injection valve of the present invention, and is a cross-sectional view taken along the line A_B of FIG. 11A. Fig. 12 is a diagram showing the method of processing the swivel element (swirler structure), and shows the processing processes (a)-(g). BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the fuel injection valve of the present invention will be described with reference to FIGS.

First, the configuration and basic operation of an embodiment of the fuel injection valve of the present invention will be described with reference to FIG.

FIG. 1 is a sectional view showing an embodiment of the fuel injection valve of the present invention. At the lower end of the nozzle 11, a turning element holding member 22 is provided via an elastic member 21. A turning element 12 made of single-crystal silicon for applying a turning force to the fuel is provided inside the turning element holding member 22. Insert the stainless steel orifice plate 1 into the lower end of the nozzle 11 and fix it by welding or the like. The orifice plate 1 is provided with a fuel injection hole 2 and a valve seat 3.

The valve body 4 is slidably guided by a hole provided at the center of the guide plate 13 and the inner diameter of the turning element holding member 22.

The valve element 4 connects the movable iron core 5, the cylindrical member 6, and the rod 7 by welding or the like. It is configured. The outer peripheral portion of the damper plate 8 provided inside the movable iron core 5 is supported in the vertical direction by the upper end surface of the tubular member 6. The interlocking member 10 is supported inside the inner fixed iron core 9 so as to be slidable in the axial direction. The tip of the interlocking member 10 is in contact with the inner periphery of the damper plate 8. The outer peripheral portion of the damper plate 8 is supported, and the inner peripheral portion bends in the axial direction, thereby functioning as a leaf spring.

The nozzle 11 is fixed inside the nozzle housing 14. A ring 15 for adjusting the stroke of the valve body 4 is provided at the upper end of the nozzle 11. Inside fixed A spring pin 19 is fixed inside the iron core 9. The spring 20 is provided in a compressed state with the lower end of the spring pin 19 as a fixed end. The spring force of the spring 20 is transmitted to the valve body 4 via the interlocking member 10 and the damper plate 8, and the valve body 4 is pressed against the valve seat 3. In this closed state, the fuel passage is closed, so that the fuel supplied from the fuel supply port 23 remains inside the fuel injection valve, and the fuel injection from the fuel injection hole 2 is not performed.

Nozzle housing 1 4, moveable iron core 5, inner fixed iron core 9, plate housing 1

6. The outer fixed iron core 17 forms a magnetic circuit that loops around the coil 50.

When the injection command pulse is turned on, a current flows through the coil 50, the movable iron core 5 is attracted to the inner fixed iron core 9 by electromagnetic force, and the upper end surface of the valve body 4 has the lower end surface of the inner fixed iron core 9. Move to the position where it touches. In this open state, a gap is formed between the valve element 4 and the valve seat 3, so that the fuel passage is opened, and the fuel supplied from the fuel supply port 23 is provided with a swirling force by the swirl element 12 to rotate. The fuel is injected from the fuel injection hole 2.

When the injection command pulse is turned off, no current flows through the coil 50, and the electromagnetic force disappears. Therefore, the valve body 4 returns to the valve-closed state by the spring force of the spring 20, and the fuel injection ends.

The function of the fuel injection valve is to control the fuel supply amount by switching the position of the valve element 4 between the open state and the closed state according to the injection command pulse as described above. The Further, by injecting the fuel imparted with the swirling force by the swirling element 1 2 from the fuel injection holes 2, it is possible to form a fuel spray having a small fuel particle diameter, that is, excellent atomization characteristics. .

A fuel injection valve capable of supplying a fuel spray having a small particle diameter, that is, excellent atomization characteristics, in order to stabilize combustion of an internal combustion engine or reduce harmful components contained in exhaust gas discharged from the internal combustion engine. Is needed.

Here, with reference to FIGS. 2 to 5, the details, functions and effects of the means used for obtaining good atomization characteristics in one embodiment of the fuel injection valve of the present invention will be described in detail.

2A and 2B show a swirl element 12 used in an embodiment of the fuel injection valve of the present invention, FIG. 2A is a plan view of the swirl element 12, and FIG. It is sectional drawing.

The material of the turning element 12 is formed of single crystal silicon. In the center of the swivel element 12, a center passage 108 that is a through hole for inserting the opening 7 of the valve element 4 is formed. On the lower end surface of the swirl element 12, a swirl flow path 101 as a plurality of recesses for applying a swirl force to the fuel is formed.

The side wall of each swirl flow path 101 is formed on the convex part 102. The central passage 108 and the swirl passage 101 formed in the swirl element 12 made of single crystal silicon are formed by etching.

By using the etching force, it becomes possible to make the shapes of the central flow path 108 and the swirl flow path 101 of the swirl element 12 made of single crystal silicon highly accurate. In addition, the tip of the acute angle portion 107 which is a portion surrounded by the side wall of the adjacent swirling flow path 101 and the side wall of the central flow path 108 has a sharp edge. In other words, the acute angle portion 107 is a tip portion where the inner diameter of the convex portion 102 is in contact with the central flow path 108.

When the swirling flow path 101 is formed by cutting or sintering using a mold, the tip of the acute-angled portion 107 needs to be rounded to some extent. By using the etching process, the rounded corner (rounded corner) ) Can be set to about 0 to 0.01 mm.

If the corner radius of the tip of the acute angle portion 107 is large, there is a possibility that the swirling force of the fuel may be weakened by the vortex of the fuel generated there. If the corner radius of the tip of the acute-angled portion 107 can be reduced to about 0 to 0.01 mm by etching, the generation of fuel vortex can be suppressed, and a strong fuel swirling force can be obtained. As a result, the atomization characteristics of the fuel injection valve can be improved.

Second, the side wall of the swirling flow path 101 can be made substantially perpendicular to the end face of the swirling element 12. When the swirling flow path 101 is formed by cutting or sintering using a mold, it is necessary to provide a relatively large inclination or a square radius on the side wall of the swirling flow path 101.

By making the side wall of the swirling channel 101 substantially vertical by etching, the width of the swirling channel 101 can be made uniform in the depth direction. Therefore, the flow velocity distribution of the fuel can be made substantially uniform in the above-described depth direction, so that it is difficult to generate a non-uniform swirl force, and a uniform and strong fuel swirl force is obtained, thereby improving the atomization characteristics of the fuel injection valve. It becomes possible.

Although FIG. 2A illustrates an example in which the number of swirling channels 101 is six, the effect of the present invention can be obtained regardless of the number of swirling channels (two or more). Is not impaired. For example, the number of swirling channels 101 may be four.

Further, in FIG. 2A, the case where the side wall of the swirling channel 101 is straight is described as an example, but the present invention is applied even if the side wall of the swirling channel is curved. It is possible.

Further, in FIG. 2, the case where the side wall of the swirling flow path 101 is in the tangential direction of the central flow path 108 is described as an example, but the side wall of the swirling flow path 101 is not necessarily required. It does not need to be in the tangential direction of the central channel 108.

FIG. 3 is an enlarged partial sectional view of the vicinity of the fuel injection hole 2 in one embodiment of the fuel injection valve of the present invention.

A swivel element holding member 22 is provided, and the swivel element 12 is held at its inner diameter. The material of the turning element holding member 22 is preferably stainless steel, but is not limited to this. Not something. The inner diameter of the turning element holding member 22 is slightly smaller than the inner diameter of the turning element 12. The inner diameter of the swivel element holding member 22 is used as a slide for the rod 7.

This eliminates the need to use the inner diameter portion of the turning element 12 as a sliding guide, so that single crystal silicon can be selected as the material of the turning element 12. Further, an elastic member 21 made of a material having a smaller longitudinal elastic coefficient than single crystal silicon is provided on the upper surface of the turning element holding member 22. As the material of the elastic member 21, it is desirable to use a synthetic resin such as rubber or an alloy containing copper as a main component. . According to such a configuration, the orifice plate made of stainless steel or the like is used.

Since the elastic member 21 deforms and absorbs the axial force generated in the process of inserting and fixing the nozzle 1 into the nozzle 11, excessive compressive stress acts on the single crystal silicon swivel element 12. Can be prevented. Therefore, it becomes possible to use a brittle material such as single crystal silicon as the material of the turning element 12. Further, it is desirable to provide a minute taper portion 109 inside the end face of the orifice plate 1 facing the turning element 12.

According to this, the acute angle portion 107 of the inner diameter portion of the turning element 12 does not contact the orifice plate 1. Therefore, an excessive stress is not applied to the acute angled portion 107, so that the acute angled portion 107 can be prevented from being damaged.

Note that the taper angle of the small taper section 1◦9 should be sufficiently small. Desirably, it is about 1 to 3 degrees, but it is not limited to this.

It is needless to say that a similar effect can be obtained by providing a step-shaped relief in place of the minute taper portion 109. Further, the same effect can be obtained by providing the minute taper portion 109 or the step-shaped relief on the lower end surface of the swivel element 12 instead of providing it on the orifice plate 1 side.

Further, when the compressive stress acting on the single crystal silicon turning element 12 is not a problem, the elastic member 21 may not be provided. In FIG. 3, the fuel flows as shown in 104. The fuel supplied from the upstream of the nozzle 11 passes through the through hole 106 of the swirl element holding member 22, and from the outer periphery of the swirl element 12, passes through the swirl flow path 101 and the fuel injection hole 2 So that it flows to

FIG. 4 is an enlarged partial cross-sectional view of a part of the low door and a part of the swivel element 12 in one embodiment of the fuel injection valve of the present invention.

The inner wall 10 3 of the swivel element 12 facing the central flow path 108 of the single-crystal silicon swivel element 12 has a convex portion 10 protruding from the swirl element 12 toward the inner diameter side. 0 is provided. The method of forming the central flow path 108 includes a step of forming the central flow path 108 by etching from the upper end face of the swirl element 12, and a method of forming the central flow path by etching from the lower end face of the swirl element 12. It is preferable that the method be combined with the step of forming the path 108. By adopting such a method of forming the rotating element 12 made of single crystal silicon, it is possible to easily provide the convex portion 100 as a joint between the hole shape processed from the upper end surface and the hole shape processed from the lower end surface. Becomes possible.

The operation and effect of providing the above-described protrusion 100 on the turning element 12 made of single crystal silicon will be described.

In order to improve the atomization characteristics of the fuel injection valve, as shown in Fig. 3, the flow of the fuel should flow from the outer periphery of the swirl element 12 through the swirl flow path to the fuel injection hole 2. It is necessary. However, in configuring the fuel injection valve, the annular gap 115 must be provided also between the outer peripheral portion of the rod 7 and the inner diameter portion of the swirl element 12.

Since no swirling force acts on the fuel flowing directly to the fuel injection holes 2 through the annular gap 1 15, the atomization characteristics may be deteriorated. Therefore, it is necessary to minimize the flow rate of the fuel flowing through the annular gap 115.

For this reason, in one embodiment of the present invention, a protrusion 100 for blocking fuel flow is provided in the middle of the annular gap 115. According to this, the flow resistance when fuel passes through the annular gap 115 increases, so that the fuel flow rate flowing through the annular gap 115 can be reduced, and the atomization characteristics of the fuel are improved. It is possible Become.

Further, another operation and effect obtained by processing the central flow path 108 from the upper and lower end surfaces of the swirl element 12 will be described. For example, if the central flow path 108, which is a through hole, is etched only from the upper end face of the swivel element 12 to make it penetrate, the center formed at the lower end face of the swivel element 12 is formed. In the vicinity of the internal flow path 108, the roundness of the hole shape may be deteriorated, and the surface roughness of the lower end surface may be deteriorated. By combining the step of etching the central flow passage 108 from the upper and lower end surfaces, it is possible to prevent the above-described shape deterioration.

Note that this processing method and the function and effect can be applied to any case where a fuel flow path penetrating through a material made of single crystal silicon is to be provided. For example, the same operation and effect can be obtained when only a penetrating fuel flow path is provided without providing a swirl flow path.

FIG. 5A is a plan view showing a swirl element holding member 22 of one embodiment of the fuel injection valve of the present invention. FIG. 5B is a cross-sectional view showing the swirl element holding member 22 of one embodiment of the fuel injection valve of the present invention.

A through hole 106 is provided in the turning element holding member 22. A recess 114 is provided as a fuel passage so that the fuel passing through the through hole 106 is guided to the outer peripheral portion of the swirl element 12. At this time, the cross-sectional area of the through hole 106 on a plane perpendicular to the fuel flow is sufficiently larger than the cross-sectional area of the annular gap 115 shown in FIG. Further, the cross-sectional area of the concave portion 114 on the plane perpendicular to the fuel flow should be sufficiently larger than the cross-sectional area of the annular gap 115 shown in FIG.

With such a configuration, most of the fuel passes through the swirling flow path 101 of the swirling element 12, so that it is possible to enhance the fuel swirling force and improve the atomization characteristics. .

FIG. 6 is an enlarged partial cross-sectional view of a rod 7 and a swivel element 12 of another embodiment of the fuel injection valve of the present invention.

The diameter of the swirling element 12 on the downstream side of the central fuel flow path is smaller than the diameter on the upstream side. Even with such a configuration, when fuel passes through the annular gap 1 15 Since the flow path resistance is increased, the flow rate of the fuel flowing through the annular gap 115 can be reduced, and the characteristics of finely divided fuel can be improved.

The effect of reducing the diameter on the downstream side is to reduce the volume of fuel remaining in the portion near the fuel injection hole 2. This prevents the retained fuel from being injected from the fuel injection holes 2 without imparting the swirling force, thereby improving the atomization characteristics.

FIG. 5 is a cross-sectional view of a swirl element 12 used in another embodiment of the fuel injection valve of the present invention.

The swirl element 12 is a member that directly contacts the fuel. When the swirl element 12 is formed of single-crystal silicon, a small amount of silicon may be dissolved in the fuel. A small amount of silicon may degrade the performance of mechanical components, electronic components, sensors, and auxiliary equipment such as catalysts provided in internal combustion engines. So, the turning element

To prevent direct contact between the single crystal silicon as the base material of 12 and the fuel, the outer periphery of the orbiting element 12 has a surface made of silicon oxide film that does not dissolve in the fuel. Layer 110 is provided. As a result, a small amount of silicon can be prevented from dissolving into the fuel, so that the swirl element 12 can be formed of single-crystal silicon without worrying about adverse effects on accessories.

Preferably, the surface layer 110 is a silicon oxide film. Silicon oxide is chemically stable and does not dissolve into the fuel.

The method of providing a surface layer 110 on the swivel element 12 to prevent the material components of the swivel element 12 from dissolving in the fuel is based on the case where the swivel element 12 is formed of a material other than single crystal silicon. Can also be used.

FIG. 8 is a cross-sectional view of a swirl element 12 used in another embodiment of the fuel injection valve of the present invention.

A ring-shaped sliding member 111 made of a material different from the material of the turning element 12 is provided on the inner diameter of the turning element 12. The material of the sliding member 111 is preferably stainless steel, but is not limited thereto.

According to the configuration of the swivel element 12 having such a sliding member 111, fuel injection The sliding guide of the rod 7 can be performed without using the swivel element holding member 22 for the valve, and the component configuration of the fuel injection valve can be simplified.

FIG. 9A is a plan view of a swirl element 12 used in another embodiment of the fuel injection valve of the present invention. FIG. 9B is a cross-sectional view of a swirl element 12 used in another embodiment of the fuel injection valve of the present invention. FIG. 9C is a rear view of the swirl element 12 used in another embodiment of the fuel injection valve of the present invention.

A fuel flow path 112 is provided on the upper end face of the swirling element 112. The fuel flow channel 112 is preferably formed by etching, but is not limited to this.

According to such a configuration, it is possible to guide the fuel to the outer peripheral portion of the swirl element 12 via the fuel flow path 112 without using the swirl element holding member 22. Can be easy.

FIG. 10A is a plan view of a nozzle 11 used in another embodiment of the fuel injection valve of the present invention. FIG. 10B is a cross-sectional view of a nozzle 11 used in another embodiment of the fuel injection valve of the present invention.

Near the lower end of the nozzle 11, a radial fuel flow path 113 is provided.

Even with such a configuration, it is possible to guide the fuel to the outer peripheral portion of the swirl element 12 through the fuel flow path 113 without using the swirl element holding member 22. Can be easy.

The embodiment of the present invention described with reference to FIGS. 1 to 10 may be applied to a fuel injection valve provided with a swirl element made of a material other than single crystal silicon.

Further, in FIG. 1, the fuel injection valve of the type in which the valve body is driven by the electromagnetic attraction force has been described as an example, but the embodiment of the present invention described with reference to FIG. 1 to FIG. You may apply to an injection valve. For example, the present invention can be applied to a case where a valve element is driven using a piezo element / a giant magnetostrictive element, or a case where a valve element is driven using fuel pressure.

Further, a case in which a swirling flow path penetrating through the plate-shaped member and a central flow path penetrating through the plate-shaped member are provided, and plate-shaped members stacked above and below the plate-shaped member are provided to form a turning element There is. Also in this case, the present invention described with reference to FIGS. 1 to 10 can be applied.

FIGS. 11A and 11B show another embodiment of the swirler (swirl element) structure of the present invention, and FIGS. FIG. 11A is a plan view of a swirler (swirl element) structure, and FIG. 11B is a cross-sectional view taken along a broken line AB of FIG. 11A.

The structure of the swirler tip (pivot element chip) has a through hole 1108 formed in the center, and a flat portion 1106 and a protrusion are equally divided at an arbitrary angle on the circumference. I have. The tip of the projection is formed to be elongated so as to intersect with the tangent of the through-hole 111. On the other hand, the shape of the outer peripheral part is formed of a round part 1103 and a straight part 111.

Since the swirler is incorporated into another structure, high precision is required for the inner diameter of the through hole and the outer diameter between the outer radius and the radius.

An embodiment of the high-precision swirler processing method of the present invention will be described below.

Figure 12 shows the process of processing a slurry using silicon material and micromachining technology. First, as shown in FIG. 12 (a), a silicon wafer 1100 on which a thermal oxide film 1100 having a thickness of 100000zm (100) is formed is prepared. Next, using a photolitho process, resist coating, pattern exposure, development, and etching of the thermal oxide film were performed on one side of the thermal oxide film 1 101 formed on the surface of the silicon wafer 1101, As shown in FIG. 12 (b), a mask pattern 110a of the protrusion is formed.

Next, an aluminum thin film having a thickness of 0.3 zm is formed on the surface on which the pattern has been formed by a sputtering device. As a method of forming a thin film, a vapor deposition device, an electron beam vapor deposition device, or the like may be used. Thereafter, as shown in FIG. 12 (c), a resist is applied onto a thin aluminum film 1102 formed on the surface of the silicon wafer 110 using the photolithography process. · Etching of the aluminum thin film is performed from one side to form a rounded portion 1103 and a linear portion 1105 on the outer peripheral portion and a mask pattern 1104 of the through hole 111. In this way, a multilayer mask formed by overlapping different patterns is capable of simultaneously etching holes of different depths with a time difference. It was used to perform the machining process.

In a processing method to which this method is not applied, it is necessary to first process the outer peripheral portion and the step portion of the through-hole by etching, and then to perform the protruding portion patterning. However, when etching is performed individually, there is a problem that it is difficult to form a resist on the high step portion in the next photolithography step because a high step portion exists in the first etching.

Therefore, it is effective to apply the multilayer mask method to the swirling process of the invention. In the formation of a multi-layer mask, misalignment between the first mask and the second mask can be considered. For this reason, the second mask is formed to be smaller than the first mask by about 5 zm in consideration of the occurrence of the displacement, thereby absorbing the pattern error due to the displacement.

As shown in FIG. 12 (d), dry etching of silicon is performed to an arbitrary depth, for example, 200 zm, using the aluminum thin film as a mask. By this processing, the through-hole 1108, the round portion 1103 of the outer peripheral portion, and the straight portion 1105 are processed to a depth of 200 m. Then, after removing the aluminum thin film mask, dry etching of silicon is performed to an arbitrary depth, for example, 320 zm using the thermal oxide film as a mask, as shown in FIG. 12 (e).

By this processing, the through-hole 1108, the round part 1103 and the straight part 1105 of the outer peripheral part are processed to a depth of 520 zm, and the flat part 1106 is processed to a depth of 320 zm. Further, by this processing, processing can be performed with high accuracy up to the tip of the protrusion 1107 shown in FIG. 11B.

As described above, an inductively coupled plasma etching “ICP-RIE (Inductively Coupled Plasma-RIE)” apparatus is used as the dry etching apparatus to perform etching processing having vertical walls with an aspect ratio of about 20. I can do it.

In dry etching, there are cases where minute needles such as microglasses are formed on the etching surface, particularly on the processing bottom, depending on the processing conditions. Therefore, after the etching shown in Fig. 12 (e) is completed, the thermal oxide film is used as a mask material. The glass at the microphone opening can be removed by immersing it for a few minutes in an aqueous solution of aqueous hydration power at room temperature.

Other methods of removing micrograss include not only aqueous hydration aqueous solution, but also other wet etching solutions such as ethylenediamine pyrocatechol, tetramethylammonium hydroxide, and hydrazine. it can. Alternatively, a method of spraying and removing fine glass beads, or a method of pressing a rotating brush or the like to remove the beads may be used.

Next, after removing the thermal oxide film, a thermal oxide film 111 and an aluminum thin film 111 are formed on the entire surface of both sides of the silicon wafer 110. Then, as shown in (f) of Fig. 12, using a photolitho process, the pattern of the through-hole 1 1 108, the rounded portion 1 1 10 3 and the straight portion 1 1 5 Perform formation. The through hole 1108 and the outer shape are formed by performing the silicon dry etching. Next, after removing the mask in the order of the aluminum thin film and the thermal oxide film, dicing is performed to form a slurry. Finally, a thermal oxidation film is formed on the entire surface of the swirler to complete the process ((g) in FIG. 12).

In the above processing process, the processing of the through hole 1108 and the outer peripheral portion was performed from both sides using dry etching. This is because, in the processing from one side, as the etching depth increases, the amount of side etching on the wall surface increases, and for example, there is a possibility that the dimensions of the through hole 110 may not be within the precision.

In this case, a silicon wafer with a thickness of 1000 / m was used. However, when a silicon wafer with a thickness smaller than that, for example, a thickness of 500〃m, was used, the process shown in Fig. 12 (e) was used. After dicing, a process of forming a thermal oxide film on the entire surface can be used.

Furthermore, a particularly important part of the swirler structure is the shape of the tip of the protrusion 1107 shown in FIG. 11B, so the formation of the protrusion 1107 is processed using silicon dry etching. The through hole 1108 and the outer radius 11103 and the straight portion 1105 are processed by a combination of other processing methods such as micro blasting, ultrasonic processing, and diamond drilling. To reduce costs. A straw structure can also be provided.

The material used for the swirling element (swirler structure) of the present invention is not limited to silicon, and ceramics such as aluminum zirconia, ceramics excellent in cutting and grinding properties, or brittle materials such as glass can be used.

According to the present invention, since the turning element can be formed of a brittle material such as single crystal silicon, a turning channel having a strong turning force can be formed. Further, since the flow rate of fuel passing through the inner diameter of the swirl element can be reduced, a strong swirl force can be applied to the fuel. Therefore, a fuel injection valve having good atomization characteristics can be obtained. Industrial applicability

The present invention can be used for a fuel injection valve for an internal combustion engine. In particular, in a fuel injection valve, a swirl element made of single-crystal silicon is held in a swivel element holding part, and is fixed between a nozzle and an orifice plate via an elastic member. A convex portion is provided in the central flow path of the turning element to reduce an annular gap between the outer diameter of the turning element and the inner diameter of the turning element. The fuel flow rate flowing through the annular gap is suppressed, and a strong swirling force is applied to the fuel.

Claims

The scope of the claims

1. A fuel injection valve comprising a swirl element for imparting a swirl force to fuel, wherein the swirl element is formed of a brittle material.

The central flow path provided in the center of the turning element is a combination of a step of forming a central flow path from the upstream side of the turning element and a step of forming a central flow path from the downstream side of the turning element. A fuel injection valve formed by the following steps.

2. A fuel injection valve comprising a swirl element for imparting a swirl force to fuel, wherein the swirl element is formed of a brittle material.

A fuel injection valve, characterized in that a convex portion is formed at a substantially axially central portion of a side wall portion of a central channel provided at a central portion of the swirling element.

3. A fuel injection valve comprising: a swirl element for imparting a swirl force to fuel; wherein the swirl element is formed of a brittle material; and wherein the central part of the swirl element has a substantially circular central flow path. The fuel injection valve according to claim 1, wherein a diameter of the swirl element on a surface having a swirl flow path is smaller than a flow path diameter of the swirl element on a side opposite to the surface having the swirl flow path. 4. In a fuel injector having a swirl element for imparting swirl force to fuel,

The tip corner radius of the acute angle portion formed by the side wall of the swirl channel of the swirl element and the side wall of the central portion provided at the inner diameter portion of the swirl element is in the range of 0 to 0.01 mm. 5. A fuel injection valve comprising: a swirl element that applies a swirl force to fuel; and a valve body for controlling a fuel injection amount.

A swivel element holding member for holding the swivel element and fixing the swivel element to a nozzle is provided, and the valve body is slidably guided at an inner diameter portion of the swivel element holding member. And the fuel injection valve.

6. In a fuel injector having a swirl element for imparting swirl force to fuel,

A fuel injection valve, wherein a sliding member for slidingly guiding the valve element is provided at an inner diameter portion of the swirling element.

7. A fuel injection valve having a swirl element for imparting swirl force to fuel,

An end surface of the turning element on a side having a turning flow path;

Of the end surface of the fixed member contacting the turning element, the end surface contacting the end surface of the turning element,

A taper or a stepped portion for preventing the swirling element and the fixed member from coming into contact with each other is provided near at least one of the end surfaces near a central portion provided at an inner diameter portion of the swirling element. Fuel injection valve.

8. A fuel injection valve comprising a swirl element for imparting swirl force to fuel, wherein the swirl element is formed of single crystal silicon.

9. The fuel injection valve according to claim 9, wherein a surface layer is provided on a surface of the swirl element so that single crystal silicon as a base material of the swirl element does not come into direct contact with fuel. In the fuel injection valve of

The fuel injection valve according to claim 1, wherein the surface layer is a silicon oxide film.