WO2014050266A1

WO2014050266A1 - Fuel injection valve

Info

Publication number: WO2014050266A1
Application number: PCT/JP2013/069547
Authority: WO
Inventors: 洋史大野; 小林　信章; 貴博齋藤; 敦士中井; 岡本　良雄
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2012-09-26
Filing date: 2013-07-18
Publication date: 2014-04-03
Also published as: DE112013004715T5; IN2015DN01578A; JP2014066175A; CN104471235A

Abstract

The purpose of the invention is to provide a fuel injection valve capable of reducing dead volume. The cross-sectional shape of a corner between a side surface part (45b) and a bottom part (45a) of a swirl-creating chamber (46) and a communication passage (45) is formed into a bent shape; and with (r1) denoting the radius of the cross-sectional shape of a corner (45d) between a side surface (8a) of a valve seat member (7) of a nozzle plate (8) and the side surface part of the swirl-creating chamber and the communication passage, (r2) denoting the radius of the cross-sectional shape of a corner (45c) between the side surface part and the bottom part of the swirl-creating chamber and the communication passage, and (W) denoting the width of the swirl-creating chamber and the communication passage, the swirl-creating chamber and the communication passage are formed so as to fulfill the relationship r1 < r2 < W/2.

Description

Fuel injection valve

The present invention relates to a fuel injection valve used for fuel injection of an engine.

This type of fuel injection valve is described in Patent Document 1 below. This patent document 1 discloses a fuel injection valve having a swirl chamber in which the corners of the bottom of the swirl chamber are formed in an edge shape.

US Pat. No. 6,783,855

In the technique described in Patent Document 1, the flow rate of the fuel flowing through the swirl chamber becomes slower as it approaches the wall of the swirl chamber, and in particular, the corner at the bottom of the swirl chamber is a place where it is difficult for the fuel to flow.
When the fuel injection valve is closed, it is desirable that the volume of fuel remaining (dead volume) is small, but the bottom corner of the swirl chamber is less likely to flow fuel, contributing to the promotion of fuel miniaturization when the valve is opened. Despite this small amount, there was a risk of increasing the dead volume.
The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a fuel injection valve capable of reducing the dead volume.

In order to achieve the above object, in the present invention, the cross-sectional shape of the corner portion between the side portion and the bottom portion of the swirl application chamber and the communication passage is a curved shape.

According to the present invention, it is possible to cut the volume of the portion where the fuel that contributes to the promotion of miniaturization is small, and to reduce the dead volume without affecting the fuel miniaturization.

It is an axial sectional view of the fuel injection valve of Embodiment 1. It is an expanded sectional view near the nozzle plate of the fuel injection valve of Embodiment 1. 2 is a perspective view of a nozzle plate according to Embodiment 1. FIG. It is the top view and sectional view of the nozzle plate of Embodiment 1. It is a schematic cross section of the communicating path of Embodiment 1, and a swirl grant chamber. It is the figure which described the flow of the fuel in the perspective view of the swirl chamber of Embodiment 1, and a fuel injection hole. It is a perspective view of the nozzle plate of Embodiment 2. It is a perspective view of the nozzle plate of Embodiment 3.

[Embodiment 1]
The fuel injection valve 1 of Embodiment 1 is demonstrated.
[Configuration of fuel injection valve]
FIG. 1 is an axial sectional view of the fuel injection valve 1. The fuel injection valve 1 is a so-called low pressure fuel injection valve that is used in a gasoline engine for automobiles and injects fuel into an intake manifold.
The fuel injection valve 1 is formed integrally with a magnetic cylinder 2, a core cylinder 3 accommodated in the magnetic cylinder 2, a valve element 4 slidable in the axial direction, and the valve element 4. A valve shaft 5; a valve seat member 7 having a valve seat 6 closed by the valve body 4 when the valve is closed; and a nozzle plate 8 having a fuel injection hole through which fuel is injected when the valve is opened. The electromagnetic coil 9 slides the valve body 4 in the valve opening direction when energized, and the yoke 10 induces magnetic flux lines.

The magnetic cylinder 2 is made of a metal pipe made of a magnetic metal material such as electromagnetic stainless steel, for example, and is stepped as shown in FIG. 1 by using means such as deep drawing or press working or grinding. It is formed integrally with a cylinder. The magnetic cylinder 2 has a large-diameter portion 11 formed on one end side and a small-diameter portion 12 having a smaller diameter than the large-diameter portion 11 and formed on the other end side.
The small diameter portion 12 is formed with a thin portion 13 that is partially thinned. The small-diameter portion 12 includes a core tube housing portion 14 for housing the core tube body 3 on one end side from the thin wall portion 13 and a valve member 15 (the valve body 4, the valve shaft 5, the valve seat on the other end side from the thin wall portion 13. It is divided into a valve member accommodating portion 16 for accommodating the member 7). The thin portion 13 is formed so as to surround a gap portion between the core cylinder 3 and the valve shaft 5 in a state where the core cylinder 3 and the valve shaft 5 described later are accommodated in the magnetic cylinder 2. . The thin-walled portion 13 increases the magnetic resistance between the core tube housing portion 14 and the valve member housing portion 16 and magnetically blocks between the core tube housing portion 14 and the valve member housing portion 16.

The inner diameter of the large diameter portion 11 constitutes a fuel passage 17 that sends fuel to the valve member 15, and a fuel filter 18 that filters the fuel is provided at one end of the large diameter portion 11. A pump 47 is connected to the fuel passage 17. The pump 47 is controlled by a pump control device 54.
The core cylinder 3 is formed in a cylindrical shape having a hollow part 19 and is press-fitted into the core cylinder housing part 14 of the magnetic cylinder 2. The hollow portion 19 accommodates a spring receiver 20 fixed by means such as press fitting. A fuel passage 43 penetrating in the axial direction is formed at the center of the spring receiver 20.
The outer shape of the valve body 4 is formed in a substantially spherical shape, and has a fuel passage surface 21 cut in parallel with the axial direction of the fuel injection valve 1 on the circumference. The valve shaft 5 has a large-diameter portion 22 and a small-diameter portion 23 whose outer shape is smaller than the large-diameter portion 22.

The valve body 4 is integrally fixed to the tip of the small diameter portion 23 by welding. In addition, the black semicircle and black triangle in a figure have shown the welding location. A spring insertion hole 24 is formed at the end of the large diameter portion 22. A spring seat 25 having a smaller diameter than the spring insertion hole 24 is formed at the bottom of the spring insertion hole 24, and a stepped spring receiving portion 26 is formed. A fuel passage hole 27 is formed at the end of the small diameter portion 23. The fuel passage hole 27 communicates with the spring insertion hole 24. A fuel outflow hole 28 penetrating the outer periphery of the small diameter portion 23 and the fuel passage hole 27 is formed.
The valve seat member 7 includes a substantially conical valve seat 6, a valve body holding hole 30 formed on the one end side of the valve seat 6 so as to be substantially the same as the diameter of the valve body 4, and one end from the valve body holding hole 30. An upstream opening 31 formed with a larger diameter toward the opening side and a downstream opening 48 opened to the other end side of the valve seat 6 are formed.

The valve shaft 5 and the valve body 4 are accommodated in the magnetic cylinder 2 so as to be slidable in the axial direction. A coil spring 29 is provided between the spring receiving portion 26 of the valve shaft 5 and the spring receiver 20 to urge the valve shaft 5 and the valve body 4 to the other end side. The valve seat member 7 is inserted into the magnetic cylinder 2 and fixed to the magnetic cylinder 2 by welding. The valve seat 6 is formed so that the diameter decreases from the valve body holding hole 30 toward the downstream opening 48 at an angle of about 45 °, and the valve body 4 is seated on the valve seat 6 when the valve is closed. Yes.
An electromagnetic coil 9 is inserted into the outer periphery of the core cylinder 3 of the magnetic cylinder 2. That is, the electromagnetic coil 9 is arranged on the outer periphery of the core cylinder 3. The electromagnetic coil 9 includes a bobbin 32 formed of a resin material and a coil 33 wound around the bobbin 32. The coil 33 is connected to the electromagnetic coil control device 55 via the connector pin 34.
The electromagnetic coil control device 55 energizes the coil 33 of the electromagnetic coil 9 in accordance with the timing of injecting fuel into the combustion chamber calculated based on the information from the crank angle sensor that detects the crank angle. Open the valve.

The yoke 10 has a hollow through-hole, and is formed with a large-diameter portion 35 formed on one end opening side, a medium-diameter portion 36 formed with a smaller diameter than the large-diameter portion 35, and a diameter smaller than the medium-diameter portion 36. It is comprised from the small diameter part 37 formed in the other end opening side. The small diameter portion 37 is fitted to the outer periphery of the valve member housing portion 16. An electromagnetic coil 9 is accommodated on the inner periphery of the medium diameter portion 36. A connecting core 38 is disposed on the inner periphery of the large diameter portion 35.
The connecting core 38 is formed in a substantially C shape by a magnetic metal material or the like. The yoke 10 is connected to the magnetic cylinder 2 at the large diameter portion 35 via the small diameter portion 37 and the connecting core 38, that is, magnetically connected to the magnetic cylinder 2 at both ends of the electromagnetic coil 9. It will be. A protector 52 for holding the O-ring 40 for connecting the fuel injection valve 1 to the intake port of the engine and protecting the tip of the magnetic cylinder is attached to the tip of the yoke 10 on the other end side.

When power is supplied to the electromagnetic coil 9 through the connector pin 34, a magnetic field is generated, and the valve body 4 and the valve shaft 5 are opened against the biasing force of the coil spring 29 by the magnetic force of the magnetic field.
As shown in FIG. 1, most of the fuel injection valve 1 is covered with a resin cover 53. The portion covered with the resin cover 53 is a portion of the magnetic cylindrical body 2 excluding one end portion of the large diameter portion 11 to the electromagnetic coil 9 installation position of the small diameter portion 12 and the medium diameter portion 36 of the electromagnetic coil 9 and the yoke 10. Between the outer periphery of the connecting core 38 and the large diameter portion 35, the outer periphery of the large diameter portion 35, the outer periphery of the medium diameter portion 36, and the outer periphery of the connector pin 34. The front end portion of the connector pin 34 is formed by opening a resin cover 53 so that the connector of the control unit can be inserted.
An O-ring 39 is provided on the outer periphery of one end of the magnetic cylinder 2, and an O-ring 40 is provided on the outer periphery of the small diameter portion 37 of the yoke 10.
A nozzle plate 8 is welded to the other end side of the valve seat member 7. The nozzle plate 8 is injected with a plurality of swirl chambers 41 that give a swirl (swirl flow) to the fuel, a central chamber 42 that distributes the fuel to each swirl chamber 41, and fuel that has been swirled in the swirl chamber 41. A fuel injection hole 44 is formed.

[Configuration of nozzle plate]
FIG. 2 is an enlarged cross-sectional view of the vicinity of the nozzle plate 8 of the fuel injection valve 1. FIG. 3 is a perspective view of the nozzle plate 8. FIG. 4 is a view (FIG. 4A) of the nozzle plate viewed from one end side in the axial direction (the side in contact with the valve seat member 7), and a cross-sectional view taken along the line AA (FIG. 4B). 1 is a cross-sectional view taken along a line BB in FIG. 4A.
A swirl chamber 41 is formed on one side surface of the nozzle plate 8. Four swirl chambers 41 are formed, each including a communication path 45 and a swirl application chamber 46. Each communication path 45 is connected near the center of the nozzle plate 8. The communication path 45 is formed by a groove extending radially from the vicinity of the center of the nozzle plate 8. That is, the communication path 45 has a bottom portion 45a that becomes the bottom of the groove and a side surface portion 45b that stands up with respect to the bottom portion 45a. A swirl application chamber 46 is formed at the tip of the communication passage 45. The swirl application chamber 46 is formed in a bottomed concave shape. That is, the swirl imparting chamber 46 has a bottom portion 46a serving as a bottom and a side surface portion 46b erected on the bottom portion 46a. A fuel injection hole 44 penetrating the other end side of the nozzle plate 8 is formed in the bottom 46 a of the swirl application chamber 46.
The side surface portion 46 b of the swirl application chamber 46 is formed in a spiral shape when viewed from one end side of the nozzle plate 8. One side surface 45 b of the communication path 45 is connected to the side surface 46 b of the swirl application chamber 46 in the tangential direction.

The corner 45c between the bottom 45a and the side surface 45b of the communication passage 45 and the corner 46c between the bottom 46a and the side surface 46b of the swirl application chamber 46 are in a cross section parallel to the axial direction of the nozzle plate 8. It is formed to have an R shape (curved shape).
FIG. 5 is a schematic cross-sectional view of the communication passage 45 and the swirl application chamber 46. The radius of the corner 45d (corner portion 46d) between the side surface 8a on one end side of the nozzle plate 8 and the side surface portion 45b of the communication passage 45 (side surface portion 46b of the swirl application chamber 46) is r1, and the bottom portion 45a of the communication passage 45 is. When the depth to (the bottom 46b of the swirl imparting chamber 46) is L, the size of the radius r2 of the corner 45c of the communication passage 45 (the corner 46c of the communication passage 45) is defined by the following equation.
r1 <r2 <L / 2
The nozzle plate 8 is formed by cutting, pressing, etching, or the like, and the swirl chamber 41 and the fuel injection hole 44 are integrally formed on a single plate.

[Action]
(Fuel flow when the valve is closed)
When the coil 33 of the electromagnetic coil 9 is not energized, the valve shaft 5 is biased to the other end side by the coil spring 29 so that the valve body 4 is seated on the valve seat 6. Therefore, the space between the valve body 4 and the valve seat 6 is closed, so that fuel is not supplied to the nozzle plate 8 side.
(Fuel flow when the valve opens)
FIG. 6 is a perspective view of the swirl chamber 41 and the fuel injection hole 44 in which the fuel flow is described.
When the coil 33 of the electromagnetic coil 9 is energized, the valve shaft 5 is pulled up to one end side by the electromagnetic force against the biasing force of the coil spring 29. Therefore, the space between the valve body 4 and the valve seat 6 is released, and fuel is supplied to the nozzle plate 8 side.
The fuel supplied to the nozzle plate 8 first enters the central chamber 42, collides with the bottom surface of the central chamber 42, thereby converting the axial flow into the radial flow and flows into each communication passage 45. Since the communication path 45 is connected in the tangential direction of the swirl application chamber 46, the fuel that has passed through the communication path 45 swirls along the inner surface of the swirl application chamber 46.
A swirl force (swirl force) is applied to the fuel in the swirl imparting chamber 46, and the fuel having the swirl force is injected while swirling along the side wall portion of the fuel injection hole 44. Therefore, the fuel injected from the fuel injection hole 44 is scattered in the tangential direction of the fuel injection hole 44. The fuel spray immediately after being injected from the fuel injection hole 44 becomes a liquid film state in which the fuel is formed into a film shape on the spray surface of a substantially hollow cone shape by the edge portion of the opening of the fuel injection hole 44. Thereafter, the fuel spray that has been in the form of a film gradually starts to split and enters a liquid yarn state. Further, the splitting further proceeds, and the fuel is in a droplet state split into particles.

(Dead volume reduction)
The dead volume refers to a volume in which fuel remains in the downstream opening 48, the swirl chamber 41, and the fuel injection hole 44 when the fuel injection valve 1 is closed. When the inside of the intake manifold into which the fuel injection valve 1 injects fuel becomes negative pressure, the remaining fuel boils under reduced pressure, causing the flow rate to vary with respect to the target fuel flow rate. Note that in the case of a high-pressure fuel injection valve that directly injects fuel into the engine cylinder, there is no negative pressure in the cylinder because there is no negative pressure inside the cylinder.
By the way, the fluid generally has the highest flow velocity near the center of the flow channel, and the flow velocity is slower as it is closer to the wall of the flow channel. That is, when the corner 45c of the communication passage 45 and the corner 46c of the swirl application chamber 46 are formed in an edge shape, the

corners

45c and 46c are surrounded by walls, so that the fuel flow rate is particularly slow. That is, the fuel flowing in the vicinity of the corner portion 45c of the communication passage 45 and in the vicinity of the corner portion 46c of the swirl imparting chamber 46 has little contribution to the promotion of fuel miniaturization, but the vicinity of the corner portion 45c of the communication passage 45 and the swirl. The vicinity of the corner 46c of the applying chamber 46 was a cause of an increase in dead volume.
Therefore, in the present embodiment, the corner 45c between the bottom 45a and the side surface 45b of the communication passage 45 and the corner 46c between the bottom 46a and the side surface 46b of the swirl application chamber 46 are connected to the nozzle plate 8 with each other. It was formed to have an R shape (curved shape) in a cross section parallel to the axial direction.
As a result, the volume of the portion of the communication passage 45 and the swirl imparting chamber 46 where the fuel that contributes to the miniaturization promotion is small can be reduced, and the dead volume can be reduced without affecting the fuel miniaturization. it can.

[effect]
Hereinafter, the effect of the fuel injection valve 1 of Embodiment 1 is demonstrated.
A valve body 4 provided so as to be capable of opening and closing, a valve seat 6 on which the valve body 4 sits when the valve is closed, and a valve seat member 7 having a downstream opening 48 on the downstream side, and a valve seat member 7, a nozzle plate 8 provided downstream of the nozzle plate 8, a swirl imparting chamber 46 that is formed in a concave shape on the valve seat member 7 side of the nozzle plate 8 and that imparts a swirling force by swirling fuel therein, and a swirl imparting chamber 46. A fuel injection hole 44 formed at the bottom and penetrating to the outside, and a communication passage 45 formed in a concave shape on the valve seat member 7 side of the nozzle plate 8 and communicating the swirl chamber 46 and the downstream opening 48 of the valve seat member 7. The cross-sectional shapes of the corner portion 46c of the swirl imparting chamber 46 and the corner portion 45c of the communication passage 45 are curved, the side surface of the valve seat member 7 of the nozzle plate 8, and the swirl imparting chamber. 46 corners 46d and communication passage 4 The radius of the cross-sectional shape of the corner 45d is r1, the radius of the cross-section of the corner 46c of the swirling chamber 46 and the corner 45c of the communication passage 45 is r2, and the width of the swirling chamber 46 and the communication passage 45 is W. Sometimes r2 <W / 2
The swirl imparting chamber 46 and the communication path 45 were formed so as to satisfy the following formula.
As another example, when the depths of the swirl chamber 46 and the communication passage 45 are L,
r1 <r2 <L / 2
The swirl imparting chamber 46 and the communication path 45 were formed so as to satisfy the following formula.
Therefore, the volume of the portion of the communication passage 45 and the swirl imparting chamber 46 where the fuel that contributes to the miniaturization promotion is small can be reduced, and the dead volume can be reduced without affecting the fuel miniaturization. .

As mentioned above, although this invention was demonstrated based on Embodiment 1, the concrete structure of each invention is not limited to Embodiment 1, Even if there is a design change etc. in the range which does not deviate from the summary of invention. Are included in the present invention.

(Change in number of swirl rooms)
In the fuel injection valve 1 of the first embodiment, four swirl chambers 41 are formed. However, the number of the swirl chambers 41 may be appropriately changed according to the design of the fuel injection amount.
[Embodiment 2]
FIG. 7 is a perspective view of the nozzle plate 8 used in the fuel injection valve of the second embodiment. For example, two swirl chambers 41 may be formed as shown in this figure.
[Embodiment 3]
FIG. 8 is a view showing the nozzle plate 8 provided for the fuel injection valve of the third embodiment. For example, six swirl chambers 41 may be formed as shown in FIG.

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 4 Valve body 6 Valve seat 7 Valve seat member 8 Nozzle plate 44 Fuel injection hole (injection hole)
45 communication path 45a bottom 45b side 45c corner 45d corner 46 swirl application chamber 46b side 46c corner 46d corner 48 downstream opening (opening)

Claims

A valve body provided to be capable of opening and closing; and
A valve seat on which the valve body is seated when the valve is closed, and a valve seat member having an opening on the downstream side;
A nozzle plate provided downstream of the valve seat member;
A swirl imparting chamber that is formed in a concave shape on the valve seat member side of the nozzle plate and that swirls fuel inside to impart a swirling force;
An injection hole formed at the bottom of the swirl application chamber and penetrating to the outside;
A communication path formed in a concave shape on the valve seat member side of the nozzle plate, and communicating the swirl application chamber and the opening of the valve seat member;
In a fuel injection valve equipped with
Forming a cross-sectional shape of a corner portion between a side surface portion and a bottom portion of the swirl application chamber and the communication path into a curved surface shape;
When the radius of the cross-sectional shape of the corner portion between the side surface portion and the bottom portion of the swirl application chamber and the communication path is r2, and the width of the swirl application chamber and the communication path is W,
r2 <W / 2
A fuel injection valve characterized in that the swirl application chamber and the communication passage are formed so as to satisfy the following formula.
The fuel injection valve according to claim 1, wherein
The radius of the cross-sectional shape of the corner between the side surface of the valve seat member of the nozzle plate and the side portion of the swirl application chamber and the communication path is r1, and the width of the swirl application chamber and the communication path is W. When r1 <r2 <W / 2
A fuel injection valve characterized in that the swirl application chamber and the communication passage are formed so as to satisfy the following formula.
The fuel injection valve according to claim 1, wherein
The fuel injection valve according to claim 1, wherein the swirling chamber and the communication path are processed by cutting, pressing or etching.
The fuel injection valve according to claim 2,
The fuel injection valve according to claim 1, wherein the swirling chamber and the communication path are processed by cutting, pressing or etching.
The fuel injection valve according to claim 1, wherein
2. A fuel injection valve comprising two swirl application chambers.
The fuel injection valve according to claim 1, wherein
6. A fuel injection valve comprising six swirl application chambers.
The fuel injection valve according to claim 2,
2. A fuel injection valve comprising two swirl application chambers.
The fuel injection valve according to claim 2,
6. A fuel injection valve comprising six swirl application chambers.