JPH11200998A - Fluid injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid injection nozzle which can accelerate atomization of fluid due to the disturbance caused by the collision of fluid flows, has excellent directivity, and can form fluid spray. SOLUTION: A plate member 1 is provided on the counter-spacer side of a valve body 30 in the downstream of fuel of a needle valve 25 and has a plurality of opening parts 2 which penetrate through in the direction of plate thickness. An orifice plate 32 has a recessed face 33 and a projecting face 34 in the upstream and in the downstream of fuel respectively, and is attached to the valve body 30 in the downstream of fuel of the plate member 1, and has a plurality of orifices 32a penetrating through in the direction of plate thickness. The orifices 32a are positioned on the inner peripheral side of the opening parts 2. Consequently, it is possible to make fuel flow into a narrow clearance between a face in the downstream of fuel 3 of the plate member 1 and the recessed face 33 of the orifice plate 32 and induce the collision of fuel flows along the recessed face 33 mutually. As a result, it is possible to increase energy of mutual collision of fuel and accelerate atomization of fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid injection nozzle, and more particularly to an injection nozzle portion of a fuel injection valve for injecting and supplying fuel to an internal combustion engine for an automobile (hereinafter referred to as an internal combustion engine). It is.

[0002]

2. Description of the Related Art In such a fuel injection valve, "fine atomization of fuel" injected from an injection hole is important from the viewpoints of reduction of fuel consumption, improvement of exhaust emission, stable operation of an engine, and the like. One of the elements. As a method of promoting the atomization of the injected fuel, there are auxiliary atomizing means such as collision of air with the injected fuel, heating near the injection hole, etc., but all these atomizing means are expensive. There is a problem.

[0003] On the other hand, an orifice plate having an orifice formed at the tip of a fuel injection valve is provided to promote atomization.
2. Description of the Related Art There is known a fuel injection valve having a configuration in which a needle tip is formed flat at right angles to a needle axis direction.

[0004]

However, in the above-described fluid injection nozzle having a configuration in which a recess is formed at the tip of the needle, the fuel flows in the direction opposite to the injection direction along the recess at the tip of the needle before the fuel reaches the orifice. Since the flow and the vortex were generated and the fuel did not flow smoothly, the internal energy of the fuel was lost, and sufficient atomization could not be obtained.

On the other hand, in a fluid injection nozzle having a configuration in which the tip of the needle is formed flat at right angles to the needle axis direction, the orifice plate is recessed with respect to the needle valve. Since fuel flows while spreading in the axial direction, the internal energy is lost, and sufficient atomization cannot be obtained.

In the fuel injection valve disclosed in Japanese Patent Application Laid-Open No. 9-14090, a flow toward the orifice is induced in a flattened flow path between the flat surface of the needle tip and the inlet surface of the orifice plate. Further, the fuel flows are ejected from the orifice after colliding with each other immediately above the orifice, so that the internal energy of the fuel is effectively extracted in the form of a collision, and the fuel is effectively atomized. However, if the diameter of the orifice is further reduced for further atomization, the gap immediately above the orifice relative to the diameter of the orifice becomes relatively large, and the collision speed of the fuel decreases, which causes a problem that the atomization of the fuel is rather deteriorated. . This is because a flat flow path is formed by the gap between the flat surface at the tip of the needle and the inlet face of the orifice plate, and this gap cannot be made smaller than the distance in the needle axis direction when the needle is opened. is there.

When the orifice plate is bent to form a concave conical shape in order to increase the fuel spray angle, when the fuel flows from the inner wall surface of the flow path to the orifice plate, the degree of the flow colliding with the orifice plate is reduced. There is a problem that turbulence due to fuel collision cannot be increased. The present invention has been made in order to solve such a problem, and a fluid injection nozzle capable of forming a fluid spray having excellent directionality while promoting atomization of a fluid due to turbulence due to collision of a fluid flow. The purpose is to provide.

[0008]

According to the fluid ejecting nozzle of the present invention, a substantially disk-shaped fluid chamber is formed between the fluid downstream surface of the plate member and the concave surface of the orifice plate. Therefore, when the valve member capable of contacting the valve seat is separated from the valve seat and the fluid flows into the fluid chamber through the opening of the plate member, the main flow of this flow is changed by the orifice plate. The flow directly between the orifice and the flow passing between the orifices and facing the flow at the center of the orifice plate makes a U-turn to generate a flow toward the orifice. As a result, a flow uniformly toward the orifice can be generated.

Furthermore, by making the fluid chamber flat,
The flow along the opposing surface of the orifice plate can be created to induce mutual collision of the fluid flows just above the orifice, and the fluid ejected from the orifice plate promotes atomization due to the turbulence due to the collision and the direction A spray having a characteristic can be formed. Furthermore, since the fluid chamber can be flattened irrespective of the distance from the valve seat when the valve member is opened, the diameter of the orifice can be reduced for further atomization. By setting a small diameter orifice diameter, a large number of orifices are provided to inject a predetermined amount of injection, so that the area of the fuel injected from the orifice in contact with air is increased to further promote atomization. be able to.

According to the fluid ejecting nozzle of the present invention, in the fluid chamber defined by the surface of the plate member on the fluid downstream side and the concave surface of the orifice plate, the surface of the plate member on the fluid downstream side is And the distance from the concave surface of the orifice plate is substantially equal. For this reason, when the valve member separates from the valve seat and the fluid flows into the fluid chamber through the opening of the plate member, the main flow of the flow is changed by the orifice plate to flow directly toward the orifice. The flow that passes between the orifice and the orifice plate at the center of the orifice plate makes a U-turn to generate a flow toward the orifice, and as a result, a flow uniformly toward the orifice can be created.

Further, by flattening the fluid chamber,
The flow along the opposing surface of the orifice plate can be created to induce mutual collision of the fluid flows just above the orifice, and the fluid ejected from the orifice plate promotes atomization due to the turbulence due to the collision and the direction A spray having a characteristic can be formed. Furthermore, since the fluid chamber can be flattened irrespective of the distance from the valve seat when the valve member is opened, the diameter of the orifice can be reduced for further atomization.

Further, for example, if the surface on the fluid downstream side of the plate member is formed in a convex shape, the fluid upstream side of the orifice plate is recessed toward the fluid downstream side in accordance with the shape of the plate member, and the fluid of the orifice plate is By forming the upstream surface in a concave shape, the distance between the fluid downstream surface of the plate member and the fluid upstream surface of the orifice plate can be made substantially equal. Thus, before being recessed, the orifice provided in the orifice plate is tilted away from the center axis of the plate member toward the downstream side of the fluid. Therefore, since an orifice having a large inclination angle, which is difficult to process with a flat plate, can be easily formed, the fluid spray angle of the orifice can be easily widened, and a fluid can be ejected over a wide range.

According to the third aspect of the present invention, since the opening of the plate member is formed radially outside the orifice, the orifice is located at a position where the fluid flow from the opening does not directly flow into the orifice. Is formed, it is possible to secure an area where the spray injected from each orifice is equal. Therefore, since the atomized spray injected from each orifice is suppressed from overlapping at the injection destination, the atomized spray can be uniformly supplied.

According to the fourth aspect of the present invention, since the opening and the orifice are formed on a double concentric circle, an area where the spray injected from each orifice through the opening is equal is secured. it can. Therefore, since the atomized spray injected from each orifice is suppressed from overlapping at the injection destination, the atomized spray can be uniformly supplied.

According to the fuel supply device of the fifth aspect of the present invention, the opening is formed so as to be in contact with the intersection line between the fluid upstream surface of the plate member and the inner wall surface. For this reason, the fluid flow from the opening collides while suppressing the decrease in internal energy, so that atomized spray can be supplied uniformly. According to the fluid ejecting nozzle according to the sixth aspect of the present invention, the inner wall surface has an inclined surface whose diameter decreases in the fluid flow direction. For this reason, the flow direction along the orifice plate can be formed in the fluid flow flowing toward the orifice plate from the opening, so that the fluid does not directly flow into the orifice, and the fluids that collide with the orifice plate are separated from each other. The reduction in collision energy can be reduced. Therefore, the fluids collide with each other immediately above the orifice, and the atomization of the fluid can be promoted.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1 to 4 show a first embodiment in which the present invention is applied to a fuel injection valve of a fuel supply device for a gasoline engine.

As shown in FIG. 4, a fixed core 21 made of a ferromagnetic material is accommodated in a resin housing mold 11 of a fuel injection valve 10 as a fuel injection device. The movable core 22 made of a magnetic material is formed in a cylindrical shape, and is disposed in the internal space of the non-magnetic pipe 23 and the magnetic pipe 24. The outer diameter of the movable core 22 is set slightly smaller than the inner diameter of the nonmagnetic pipe 23,
Are slidably supported by the non-magnetic pipe 23. The movable core 22 faces the fixed core 21 in the axial direction, and is disposed so as to form a predetermined gap with the lower end surface of the fixed core 21.

The non-magnetic pipe 23 is fitted around the outer periphery of the movable core side end of the fixed core 21 and is fixed by laser welding or the like. A magnetic pipe 24 made of a magnetic material and formed in a stepped pipe shape is connected to an end of the non-magnetic pipe 23 opposite to the fixed core. The non-fixed core side of the non-magnetic pipe 23 forms a guide for the movable core 22. FIG.
As shown in FIG. 2, the tip surface 25a on the fuel injection side of the needle valve 25 as a valve member is formed in a planar shape, and the contact portion 25b is formed in a circular shape on a valve seat 31b provided on the inner wall surface 31 of the valve body 30. It can be seated annularly. At the other end of the needle valve 25, a joint 25d is formed as shown in FIG. Then, the joint 25d and the movable core 22 are laser-welded, and the needle valve 25 and the movable core 22 are integrally connected. A double chamfer as a fuel passage is provided on the outer periphery of the joint 25d.

The valve body 30 is inserted into the magnetic pipe 24 via a spacer 28, and is fixed to the magnetic pipe 24 by laser welding or the like. The thickness of the spacer 28 is adjusted so that the air gap between the fixed core 21 and the movable core 22 has a predetermined value. A plate member 1 made of stainless steel is provided on the fuel downstream side of the needle valve 25 and on the side opposite to the spacer of the valve body 30. The plate member 1 has a plate shape and has a plurality of openings 2 penetrating in the plate thickness direction.

Stainless steel orifice plate 32
Has a concave surface 33 on the fuel upstream side and a convex surface 3 on the fuel downstream side.
4 and a plate member 1
Is welded to the tip of the valve body 30 on the fuel downstream side, for example, by full circumference welding. Orifice plate 3
2 has a plurality of orifices 32a penetrating in the thickness direction.

The sleeve 40 is made of resin and is pressed into the outer periphery of the valve body 30 and the orifice plate 32 to protect the orifice plate 32. Orifices 32a, 32b formed in orifice plate 32
Is injected from the opening 40a of the sleeve 40 into the engine. One end of the compression coil spring 26 is in contact with a spring seat 22 a provided on the movable core 22, and the other end of the compression coil spring 26 is in contact with the bottom of the adjusting pipe 27. The compression coil spring 26 urges the movable core 22 and the needle valve 25 downward in FIG. 3, that is, in a direction in which the contact portion 25b is seated on the valve seat 31b of the valve body 30.

As shown in FIG. 4, the adjusting pipe 27 is pressed into the inner periphery of the fixed core 21. By adjusting the press-fitting position of the adjusting pipe 27 at the time of assembly, the urging force of the compression coil spring 26 can be adjusted. The electromagnetic coil 50 is wound around the outer periphery of a spool 51 made of resin, and the spool 51 is arranged around the fixed core 21, the non-magnetic pipe 23, and the magnetic pipe 24. A housing mold 11 is resin-molded around the outer periphery of the electromagnetic coil 50 and the spool 51, and the housing mold 11 surrounds the electromagnetic coil 50. When an exciting current flows from the terminal 52 to the electromagnetic coil 50 via a lead wire by an electronic control unit (not shown), the needle valve 25 and the movable core 22 are compressed by a compression coil spring 26.
Is sucked in the direction of the fixed core 21 against the urging force of the above, and the contact portion 25b is separated from the valve seat 31b.

The terminal 52 is a housing mold 11
And is electrically connected to the electromagnetic coil 50. The terminal 52 is connected to an electronic control unit (not shown) via a wire harness. The two metal plates 61 and 62 are provided such that one upper end is in contact with the outer periphery of the fixed core 21 and the other lower end is in contact with the outer periphery of the magnetic pipe 24. It is a member that forms a road. These two metal plates 6
The electromagnetic coil 50 is protected by 1 and 62.

The filter 63 is disposed above the fixed core 21 and is pumped from a fuel tank by a fuel pump or the like to remove foreign matter such as dust in the fuel flowing into the fuel injection valve 10. The fuel flowing into the fixed core 21 through the filter 63 flows from the adjusting pipe 27 to the gap between the two chamfers formed at the joint 25 d of the needle valve 25, and further, the sliding between the valve body 30 and the needle valve 25. It passes through the gap between the four chamfered portions formed in the portion and reaches a valve portion formed by the contact portion 25b of the needle valve 25 and the valve seat 31b. As shown in FIG. 1, the contact portion 25b is
When the seat is separated from b, fuel flows into the fuel chamber 35 via the opening 2 from the gap formed by the contact portion 25b and the valve seat 31b.

The fuel chamber 35 as a fluid chamber is defined by the fluid downstream side surface 3 of the plate member 1 and the concave surface 33 of the orifice plate 32 and is formed in a substantially disc shape. Hereinafter, the structures of the needle valve 25, the valve body 30, the plate member 1, and the orifice plate 32 will be sequentially described in detail. (1) Needle valve 25 As shown in FIG.
5a, the contact portion 25b, and the distal end surface 25a and the contact portion 25
and b. Tip surface 25
a is formed on the inner peripheral side of the contact portion 25b, and its center is located on the axis of the needle valve 25.

(2) Valve Body 30 The inside diameter of the valve body 30 is reduced toward the orifice plate 32 from the vicinity of the tip, and is conical with the inner wall surface 31 forming the fuel passage as the fluid passage on the orifice plate 32 side. A slope 31a is formed. The contact portion 25b of the needle valve 25 can be seated on a valve seat 31b formed on the conical slope 31a.

(3) Plate Member 1 As shown in FIG. 2A, the plate member 1 forming the inner wall of the fuel inlet to the fuel chamber 35 penetrates the plate member 1 in the plate thickness direction and has a diameter. 8 are formed in total. As shown in FIG. 1, the opening 2 is formed so as to be in contact with the intersection line between the fuel upstream side surface 6 of the plate member 1 and the conical slope 31a.

(4) Orifice Plate 32 The orifice plate 32 for controlling the flow direction of the spray is
As shown in FIG. 1, it is recessed at the fuel downstream side by the bent portions 36 and 37, has a concave surface 33 at the fuel upstream side, and has a convex surface 34 at the fuel downstream side. The orifice plate 32 has an orifice plate 32 as shown in FIG.
Are formed in the thickness direction to form a total of four orifices 32a having the same diameter. As shown in FIG. 1, the orifice 32a is inclined away from the central axis toward the fuel downstream side of the orifice plate 32.

As shown in FIG. 2A, the opening 2 and the orifice 32a are arranged concentrically, and the orifice 32a is located on the inner peripheral side of the opening 2. For this reason, when the needle valve 25 and the valve body 30 are separated from each other, the fuel flowing into the fuel chamber 35 from between the contact portion 25b and the valve seat 31b flows along the conical slope 31a, and then opens at the opening. After the direction is changed by the concave surface 33 of the orifice plate 32 without directly flowing through the orifice 32a through the orifice 32a, the plate member 1 advances a predetermined distance between the fuel downstream side surface 3 and the concave surface 33 of the plate member 1. Therefore, the fuel can be efficiently atomized without the main flow of the fuel flowing directly into the orifice 32a. In addition, the orifice 32a can be arranged in a range that does not approach the center of the orifice plate 32 too much and does not spread too much on the outer peripheral side of the orifice plate 32. Therefore, the strength of the fuel flow flowing into each orifice 32a can be made substantially uniform regardless of the flow direction. As a result, the internal energy of the fuel can be efficiently used in the form of turbulence due to collision between flows, and extremely ideal atomization can be realized.

Further, since a uniform collision can be obtained at the center of the entrance of the orifice 32a, it is possible to obtain an extremely directional spray along the inclination of the entire side wall forming the orifice 32a. Next, the operation of the fuel injection valve 10 will be described. (1) When the power to the electromagnetic coil 50 is turned off, the movable core 22 and the needle valve 25 are urged downward in FIG. 3 by the urging force of the compression coil spring 26, and the contact portion 25b of the needle valve 25 is moved to the valve seat 31b. To sit down. As a result, the fuel injection from the orifice 32a is shut off.

(2) When energization of the electromagnetic coil 50 is turned on, the movable core 22 is attracted to the fixed core 21 against the urging force of the compression coil spring 26.
The fifth contact portion 25b is separated from the valve seat 31b. As a result, fuel flows into the fuel chamber 35 through the opening 2 from the gap between the contact portion 25b and the valve seat 31b. The fuel that has flowed into the fuel chamber 35 travels toward the center of the fuel chamber 35. The fuel toward the center collides with each other at the center to generate a radially outward flow, and the radially outward fuel and the central fuel flow collide on the orifice 32a.
Then, the atomized fuel is injected from the orifice 32a.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention. The second embodiment is a modification of the first embodiment,
The shape, area and number of openings 2 of the plate member 1 shown in FIG. 2 are changed. In the second embodiment, the opening 4 and the orifice 32a are respectively formed on concentric circles, and the opening 4 has an arc shape, and a total of three openings 4 are formed. A total of four orifices 32 a are formed, and are located on the inner peripheral side of the opening 4.

In the second embodiment, since the total area of the openings is larger than that in the first embodiment, the fuel flow from the openings 4 collides while suppressing the decrease in internal energy, and is injected from the orifice 32a. The atomization of the fuel spray is promoted, and the atomized spray can be supplied more uniformly. In the first and second embodiments described above, when the needle valve 25 is separated from the conical slope 31a of the valve body 30, the opening 2 of the plate member 1 is removed from the gap between the contact part 25b and the conical slope 31a. Through orifice plate 32
The fuel advances to the side and is bent toward the fuel chamber 35 by hitting the concave surface 33 of the orifice plate 32 to form a fuel flow along the concave surface 33. This fuel flow is divided into a flow directly toward the orifice 32a and a flow passing between the orifices 32a, and the flow passing between the orifices 32a makes a U-turn toward the orifice 32a by a flow facing the center of the orifice plate 32. Becomes The fuel flows from the radially opposite directions toward the orifice 32a collide with each other just above the orifice 32a,
Creates unstable flow conditions and promotes atomization of fuel. That is, the fuel can flow in a narrow gap between the fuel downstream side surface 3 of the plate member 1 and the concave surface 33 of the orifice plate 32, and the collision of the fuel flows along the concave surface 33 can be induced. This makes it possible to increase the energy of collision between fuels and promote atomization of the fuel.

Further, in the first embodiment and the second embodiment, the fuel chamber 35 can be flattened regardless of the distance between the contact portion 25b and the valve seat 31b when the needle valve 25 is separated from the conical slope 31a. By providing a large number of orifices with small diameter orifices, the injection amount can be increased.
By allowing a predetermined flow rate of fuel to pass through a large number of orifices, it is possible to increase the area of the fuel injected from the orifices in contact with air, thereby promoting atomization. Further, by making the orifice diameter small, it is easy to form a fuel passage between orifices in an orifice plate having a predetermined area.

(Third Embodiment) FIG. 6 shows a third embodiment of the present invention.
Shown in The substantially same parts as those in the first embodiment are denoted by the same reference numerals. In the third embodiment, the plate member 5 is formed in a conical shape projecting downstream of the fuel. The fuel upstream side surface 8 of the plate member 5 is recessed on the fuel downstream side, and the fuel downstream side surface 7 protrudes on the fuel downstream side. Plate member 5
Are formed with a total of eight openings 9 having the same diameter and penetrating the plate member 5 in the thickness direction.

The orifice plate 132 is
6 and 137, it is recessed on the fuel downstream side, has a concave surface 133 on the fuel upstream side, and has a convex surface 134 on the fuel downstream side. Further, the concave surface 133 of the orifice plate 132
Is formed in a concave conical shape so that the interval between the plate member 5 and the fuel downstream side surface 7 is substantially equal to the shape of the plate member 5. The convex surface 134 is formed in a convex conical shape similarly to the fuel downstream side surface 7 of the plate member 5. A fuel chamber 135 is formed by the fuel downstream side surface 7 of the plate member 5 and the concave surface 133 of the orifice plate 132. The orifice plate 132 has an orifice 1 having the same diameter and penetrating the orifice plate 132 in the thickness direction.
32a are formed in total of four. Orifice 132a
Is located on the inner peripheral side of the opening 9.

In the third embodiment, since the orifice plate 132 is recessed on the fuel downstream side in accordance with the shape of the plate member 5, the inclination angle of the orifice with respect to the center axis of the needle valve 25 is easily enlarged, and the fuel spray The angle can be enlarged. Therefore, a fuel injection valve that requires a large spray angle can be easily manufactured. Further, the fuel downstream side surface 7 of the plate member 5 and the orifice plate 132
The fuel flow that has flowed into the fuel chamber 135 as a fluid chamber defined by the concave surface 133 collides with the orifice plate 132 without being directly injected from each of the orifices 132a, and then changes direction and collides with each other immediately above the orifice 132a. Since the fuel is injected after that, the atomization of the fuel spray injected from the orifice 132a is promoted as in the first embodiment.

In the above-described embodiments of the present invention, when the needle valve and the valve body are separated from each other,
A portion of the fuel flowing from the opening of the plate member toward the center of the orifice plate is changed in direction at the center of the orifice plate, and makes a U-turn toward each orifice. The fuel flow that makes a U-turn from the center of the orifice plate collides with the flow flowing from the outer periphery of the orifice plate to the orifice at the center of the orifice inlet.

The strength of the flow flowing into the orifice after making a U-turn at the center of the orifice plate is almost the same as the flow flowing into the orifice from the outer periphery of the orifice plate. Efficient atomization can be achieved. At the same time, fuel collides at the center of the inlet of the orifice, and uniform collision is obtained. Therefore, the directionality of the atomized fuel is well controlled by the orifice.

Since the atomization of the fuel spray injected from the orifice is promoted as described above, the fuel spray is easily mixed with air over a wide range, and the combustion efficiency of the fuel is increased. Harmful substances and fuel consumption can be reduced. Although the number of orifices is set to four in the above embodiments of the present invention, the number of orifices may be two or more in the present invention.

[Brief description of the drawings]

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

FIG. 2A is a plan view showing the arrangement of openings and orifices in the present embodiment, and FIG. 2B is a cross-sectional view taken along the line BB of FIG.

FIG. 3 shows a fuel injection valve according to a first embodiment of the present invention, and is an enlarged view of a main part of FIG. 4;

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

FIG. 5 is a plan view showing an arrangement of an opening of an injection nozzle and an orifice according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing an injection nozzle part of a fuel injection valve according to a third embodiment of the present invention.

[Explanation of symbols]

 1,5 Plate member 2,4,9 Opening 3,7 Fuel downstream side 6,8 Fuel upstream side 10 Fuel injection valve 21 Fixed core 22 Movable core 25 Needle valve (valve member) 25a Tip surface 25b Contact portion 30 Nozzle Body 31 Inner wall surface 31a Conical slope 31b Valve seat 32 Orifice plate 32a Orifice 33 Concave surface 34 Convex surface 35 Fuel chamber (fluid chamber)

Claims (6)

[Claims] 1. A valve body having a valve seat provided on an inner wall surface forming a fluid passage, and a contact portion which can be annularly seated on the valve seat, wherein the contact portion is separated from the valve seat. A valve member that opens and closes the fluid passage by sitting on the valve seat, a plate member that is provided in the valve body downstream of the valve member on the fluid side, and has a plurality of openings penetrating in a plate thickness direction; A concave surface which is attached to the valve body on the fluid downstream side of the plate member and forms a substantially disk-shaped fluid chamber between the plate member and the fluid downstream surface, and a plurality of holes penetrating in the plate thickness direction. A fluid ejection nozzle, comprising: an orifice plate having an orifice. 2. A valve body having a valve seat provided on an inner wall surface forming a fluid passage, and a contact portion which can be annularly seated on the valve seat, wherein the contact portion is separated from the valve seat, A valve member that opens and closes the fluid passage by sitting on the valve seat, a plate member that is provided in the valve body downstream of the valve member on the fluid side, and has a plurality of openings penetrating in a plate thickness direction; An orifice plate attached to the valve body downstream of the plate member and defining a fluid chamber between the valve member and a downstream surface of the plate member, and a plurality of orifices penetrating in a plate thickness direction; A fluid ejection nozzle, wherein in the fluid chamber, a distance between a fluid downstream surface of the plate member and the concave surface is substantially equal. 3. The fluid ejection nozzle according to claim 1, wherein the opening is formed radially outside the orifice. 4. The fluid ejection nozzle according to claim 3, wherein the opening and the orifice are formed on a double concentric circle. 5. The fluid ejecting nozzle according to claim 3, wherein the opening is formed so as to be in contact with a line of intersection between the fluid upstream surface of the plate member and the inner wall surface. 6. The fluid ejection nozzle according to claim 1, wherein the inner wall surface has an inclined surface whose diameter decreases in a flow direction of the fluid.