JP2013185522A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection valve capable of setting a distribution of fuel injection in accordance with a target range of fuel injection.SOLUTION: A distribution of a liquid film thickness of a fuel at an outlet of a fuel injecting hole is set according to a shape of a target range of fuel injection.

Description

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

  As this type of technology, the technology described in Patent Document 1 below is disclosed. This publication discloses that a passage plate in which a swirl chamber is formed and an injector plate in which a fuel injection hole that opens in the swirl chamber is welded to a valve seat member.

JP 2003-336562 A

In the technique described in Patent Document 1, since the fuel injection hole outlet is formed in a circular shape, the fuel injected from the fuel injection hole spreads in a conical shape. Therefore, when the fuel injection target range is not circular, there is a possibility that fuel cannot be sufficiently injected into the range.
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 setting a fuel injection distribution in accordance with a fuel injection target range.

  In order to achieve the above object, in the present invention, the thickness distribution of the liquid film of the fuel at the outlet of the fuel injection hole is set according to the shape of the fuel injection target range.

  According to the present invention, the fuel spray shape can be other than circular.

It is an axial sectional view of the fuel injection valve of Example 1. It is an expanded sectional view near the nozzle plate of the fuel injection valve of Example 1. It is the top view which looked at the nozzle plate of Example 1 from the axial direction one end side (upstream side). It is an enlarged view of the swirl chamber and fuel injection hole part of Example 1. It is a figure which shows the mode of the fuel which turns in the fuel-injection hole of Example 1. FIG. FIG. 3 is a diagram illustrating a fuel liquid film at the fuel injection hole inlet according to the first embodiment. FIG. 3 is a diagram illustrating a fuel liquid film at a fuel injection hole outlet according to the first embodiment. It is an equivalence line which shows the distribution amount of the fuel of the injection destination of a comparative example. 2 is an equivalence line showing the fuel distribution amount of the injection destination of the first embodiment. It is a figure explaining the flow of the fuel in the cylinder of Example 1. FIG. It is a figure explaining the flow of the fuel in the cylinder of Example 1. FIG. It is the figure shown about the range which injects the fuel of Example 1. FIG. It is an expanded sectional view near the nozzle plate of the fuel injection valve of other examples. It is an expanded sectional view near the nozzle plate of the fuel injection valve of other examples.

[Example 1]
The fuel injection valve 1 according to the first embodiment will be described.
[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 an automobile gasoline engine and injects fuel into the intake port 49.
The fuel injection valve 1 includes a magnetic cylinder 2, a core cylinder 3 accommodated in the magnetic cylinder 2, a valve element 4 slidable in the axial direction, and a valve shaft formed integrally with the valve element 4. 5; a valve seat member 7 having a valve seat 6 that is closed by the valve body 4 when the valve is closed; a nozzle plate 8 having a fuel injection hole 44 through which fuel is injected when the valve is opened; and the valve body 4 is opened when energized. It has an electromagnetic coil 9 that slides in the valve direction and a yoke 10 that induces magnetic flux lines.

The magnetic cylinder 2 is made of a metal pipe or the like formed of a magnetic metal material such as electromagnetic stainless steel, and is stepped as shown in FIG. 1 by using means such as deep drawing or pressing or grinding. It is integrally formed in a cylindrical shape. 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 that houses the core tube body 3 on one end side from the thin wall portion 13, and a valve member 15 (valve body 4, valve shaft 5, valve seat member on the other end side from the thin wall portion 13 7) and is divided into a valve member accommodating portion 16 for accommodating. 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 wall 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 for sending fuel to the valve member 15, and a fuel filter 18 for filtering 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 portion 19 and is press-fitted into the core cylinder housing portion 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 from the valve seat 6 so as to be substantially the same as the diameter of the valve body 4, and one end opening side from the valve body holding hole 30. An upstream opening 31 having a larger diameter and a downstream opening 48 that opens to the other end 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 receiver 26 and the spring receiver 20 of the valve shaft 5 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 its diameter decreases from the valve body holding hole 30 toward the downstream opening 48, and the valve body 4 is seated on the valve seat 6 when the valve is closed.
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 disposed 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 to energize the fuel injection valve 1 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 has 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 composed of a small diameter portion 37 formed on the end opening side. The small diameter portion 37 is fitted on 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 via the small-diameter portion 37 and the connecting core 38, that is, is magnetically connected to the magnetic cylinder 2 at both ends of the electromagnetic coil 9. 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.
Most of the fuel injection valve 1 is covered with a resin cover 53. The portion covered with the resin cover 53 is from the portion excluding one end portion of the large-diameter portion 11 of the magnetic cylindrical body 2 to the electromagnetic coil 9 installation position of the small-diameter portion 12 to 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 tip 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.
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 a 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 plan view of the nozzle plate 8 as viewed from one end side (upstream side) in the axial direction. The configuration of the nozzle plate 8 will be described with reference to FIGS. The cross section of the nozzle plate 8 in FIG. 2 is the AA cross section shown in FIG.
A swirl chamber 41 and a central chamber 42 are formed on one side surface of the nozzle plate 8. Two swirl chambers 41 are formed, each including a communication path 45 and a swirl imparting chamber 46. Each communication path 45 is connected near the center of the nozzle plate 8, and a central chamber 42 is formed at the connection portion. A swirl application chamber 46 is formed at the tip of the communication path 45, and the communication path 45 is connected in the tangential direction of the swirl application chamber 46. The swirl imparting chamber 46 is formed in a bottomed circular concave shape having an inner surface and a bottom portion, and a fuel injection hole 44 that is a through hole is formed in the bottom portion.
Each fuel injection hole 44 is formed in an oblique direction with respect to the axial direction of the nozzle plate 8 by a tool that can be formed in a cylindrical shape. Thus, each fuel injection hole 44 has an elliptical shape in a cross section perpendicular to the axial direction of the nozzle plate 8.

[Action]
(Fuel flow when the valve opens)
FIG. 4 is an enlarged view of the swirl chamber 41 and the fuel injection hole 44, and shows how fuel is injected from the fuel injection hole 44.
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 urging 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 of the central chamber 42, is converted from an axial flow to a radial flow, and flows into each communication passage 45. Since the communication passage 45 is connected in the tangential direction of the swirl application chamber 46, the fuel that has passed through the communication passage 45 swirls along the inner surface of the swirl application chamber 46.
A swirl force (swirl force) is imparted 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 spreads conically in a thin liquid film state by the edge portion of the opening of the fuel injection hole 44. Thereafter, the fuel in the liquid film state is separated into droplets that are atomized.
As a result, fuel vaporization can be promoted, and in particular, generation of nitrogen oxides and the like during low temperature starting can be reduced.

(Fuel injection range)
FIG. 5 is a view showing the state of fuel swirling in the fuel injection hole 44. FIG. 6 is a view showing a fuel liquid film at the inlet 44 a of the fuel injection hole 44. FIG. 7 is a view showing a fuel liquid film at the outlet 44 b of the fuel injection hole 44.
A liquid film is formed on the fuel swirled in the swirl application chamber 46 along the peripheral wall of the fuel injection hole 44. Air enters the swirl center of the fuel to form a cavity. At this time, the fuel liquid film distribution at the fuel injection hole inlet 44a is different from the fuel liquid film distribution at the fuel injection hole outlet 44b. That is, the deviation in the thickness of the liquid film at the fuel injection hole outlet 44b shown in FIG. 7 is larger than the deviation in the thickness of the liquid film at the fuel injection hole inlet 44a shown in FIG. In other words, the difference between the liquid film thickness a and b at the fuel injection hole outlet 44b shown in FIG. 7 is different from the difference between the liquid film thickness a and b at the fuel injection hole inlet 44a shown in FIG. growing.
When the liquid film is ejected from the circular amount ejection outlet 44b, the liquid film in the range indicated by the alternate long and short dash line in FIG. 7 jumps out to the position indicated by the dotted line. That is, the deviation of the liquid film at the outlet 44b becomes the deviation of the fuel at the injection destination.

FIG. 8 and FIG. 9 are isolines showing the distribution amount of the fuel at the injection destination. FIG. 8 is an equivalence line when the thickness of the liquid film at the fuel injection hole outlet 44b is uniform on the circumference, and FIG. 9 is an equivalence line when fuel is injected by the fuel injection valve 1 of the first embodiment. .
As shown in FIG. 8, when the thickness of the liquid film at the fuel injection hole outlet 44b is uniform on the circumference, the fuel is distributed in a substantially circular shape, and the amount of fuel distribution is the largest in the vicinity of the center. On the other hand, as shown in FIG. 9, when the thickness of the liquid film at the fuel injection hole outlet 44b is uneven on the circumference by the fuel injection valve 1 of the first embodiment, the fuel is distributed in a crescent shape, and the fuel distribution The position with the largest amount is far from the center. That is, by making the thickness of the liquid film at the fuel injection hole outlet 44b non-uniform on the circumference, the fuel injection range can be made other than circular.

(Fuel injection target range)
Conventionally, the fuel injection hole is formed in parallel with the axial direction of the nozzle plate, and the fuel injection hole outlet is formed in a circular shape. Therefore, the fuel injected from the fuel injection hole spreads in a conical shape. However, when the target injection range of the fuel is not circular, there is a possibility that the fuel cannot be sufficiently injected into the range.
Here, an example in which the fuel injection target range is not circular is shown.
FIGS. 10 and 11 are views for explaining the flow of fuel in the cylinder 56 depending on the position at which fuel is injected from the fuel injection valve 1 into the intake manifold 49. FIG. 10 is a diagram showing the flow of fuel in the cylinder 56 when fuel is injected to the outside of the valve 50 (a position far from the spark plug 57), and FIG. 11 shows the fuel inside the valve 50 (a position close to the spark plug 57). FIG. 6 is a diagram showing the flow of fuel in a cylinder 56 when is injected.

As shown in FIG. 10, when fuel is injected to the outside of the valve 50, the fuel is injected toward the wall of the cylinder 56, so that the fuel easily adheres to the wall of the cylinder 56, and the attached fuel hardly contributes to combustion. Can't get good combustion.
On the other hand, as shown in FIG. 11, when fuel is injected inside the valve 50, the fuel is injected at a position away from the wall of the cylinder 56, so that it is difficult for the fuel to adhere to the wall of the cylinder 56, and the spark plug 57 Because it is easy to collect fuel in the vicinity, good combustion can be obtained.
That is, in order to obtain good combustion, it is desired to inject fuel inside the valve 50. FIG. 12 is a diagram showing a range in which fuel is injected. When fuel is injected into the inside of the valve 50, it is necessary to inject the fuel into a crescent-shaped range along the circumference of the valve 50 as shown by the range of dots in FIG.
Therefore, as in the fuel injection valve 1 of the first embodiment, the fuel is injected into the fuel crescent as shown in FIG. 9 by making the fuel injection holes 44 obliquely with respect to the axial direction of the nozzle plate 8 with a circular tool. The fuel can be sufficiently injected into the target injection range of the fuel.

〔effect〕
The effects of the fuel injection valve 1 of the first embodiment are listed below.
(1) A valve body 4 slidably provided, a valve seat 6 on which the valve body 4 sits when the valve is closed is formed on one end side, and is formed on the other end side of the valve seat member 7. A plurality of swirl imparting chambers 46 for imparting swirls to the fuel, and nozzle plates 8 having fuel injection holes 44 communicating with the respective swirl imparting chambers 46 for injecting the fuel to which the swirls have been imparted. The thickness distribution of the fuel liquid film at the fuel injection hole outlet 44b is set in accordance with the shape of the injection position.
Therefore, the fuel injection range can be other than circular.
(2) The fuel injection hole 44 has an elliptical cross section.
Therefore, the thickness distribution of the fuel liquid film at the fuel injection hole outlet 44b can be biased.

[Other Examples]
As described above, the present invention has been described based on the first embodiment. However, the specific configuration of each invention is not limited to the first embodiment, and even if there is a design change or the like without departing from the gist of the present invention. Are included in the present invention.
13 and 14 are enlarged sectional views of the vicinity of the nozzle plate 8 of the fuel injection valve 1.
In the fuel injection valve 1 of the first embodiment, two swirl chambers 41 are formed. However, as shown in FIGS. 13 and 14, four swirl chambers 41 may be formed or more. When four swirl chambers 41 are formed, the swirl application chambers 46 may face each other as shown in FIG. 13, or may face each other as shown in FIG. .
In the first embodiment, the fuel injection holes 44 are formed so as to be inclined with respect to the axial direction of the nozzle plate 8 so that the thickness distribution of the fuel liquid film at the fuel injection hole outlet 44b is biased. However, the thickness distribution of the fuel liquid film at the fuel injection hole outlet 44b may be biased by other configurations.
In the first embodiment, the fuel injection distribution is in a crescent shape, but may be set as appropriate in accordance with the fuel injection target range.

1 Fuel injection valve
4 Disc
6 Valve seat
7 Valve seat member
8 Nozzle plate
44 Fuel injection hole
44b Fuel injection hole outlet
46 Swirl grant room

Claims (2)

A valve body slidably provided;
A valve seat member formed on one end side of a valve seat on which the valve body sits when the valve is closed;
A plurality of swirl application chambers formed on the other end side of the valve seat member for applying a swirl to the fuel;
A nozzle plate formed with a fuel injection hole for injecting fuel to which the swirl is imparted in communication with each swirl imparting chamber;
Provided,
A fuel injection valve characterized in that a thickness distribution of a liquid film of fuel at an outlet of the fuel injection hole is set according to a shape of a fuel injection target range. The fuel injection valve according to claim 1, wherein
The fuel injection valve, wherein the fuel injection hole is formed in an ellipse.

Images