JP2012122441A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a hollow-cone shaped spray that is stabilized in a spray state by a simple constitution.SOLUTION: Injection oles 27-1, 27-6 are arranged at equal intervals on a concentric circle whose center coincides with the center of an orifice plate 23, at the same time, the injection holes 27-1, 27-6 are formed so as to incline with respect to a Z-axis direction which passes through the center of the orifice plate 23 and coincides with an axis of an injection valve at a prescribed injection-hole angle θINC, a line obtained by projecting the center axis of each injection hole 27-1, 27-6 on the orifice plate 23 is formed at a prescribed circumferential inclination angle θcir with respect to a line for connecting a point at which the center axis of each injection hole 27-1, 27-6 crosses a flat face at which the orifice plate 23 is located and the center of the concentric circle, and thus the stable hollow-cone shaped spray can be obtained.

Description

  The present invention relates to a fuel injection valve, and more particularly to a fuel injection valve suitable for a port injection type internal combustion engine, which is intended to stabilize a spray shape in a holocone spray.

As this type of fuel injection valve, for example, a fuel injection valve has been proposed in which a roughly cone-shaped spray can be separately formed from one fuel injection valve to two ports (for example, Patent Document 1). reference).
In addition, a fuel injection valve configured to add a swirl to a holo-cone-shaped spray for atomization of the spray has been proposed (see, for example, Patent Document 2).

JP 2004-225598 A (page 5-8, FIGS. 1 to 8) JP 2000-509462 A (page 6-9, FIG. 1 to FIG. 5)

However, in the fuel injection valve disclosed in the former publication, since the spray shape is not a holo-cone shape, the penetration force of the spray is still strong and does not necessarily meet the demand for reduction of the penetration force. There is a problem.
Further, in the fuel injection valve disclosed in the latter publication, in order to generate a strong swirl flow (swirl) at the periphery of the spray, it is necessary to provide a swirl generator upstream of the nozzle hole. There is a problem that the number of points increases, the structure becomes complicated, and the price increases.

  The present invention has been made in view of the above circumstances, and provides a fuel injection valve capable of forming a holocone-shaped spray with a simple structure and a stable spray state.

In order to achieve the above object of the present invention, a fuel injection valve according to the present invention comprises:
A fuel injection valve for a port injection internal combustion engine,
On the inside surface of the fuel injection valve of the orifice plate in which a plurality of injection holes are formed, one axis along the diameter direction of the orifice plate is the X axis, and the diameter direction of the orifice plate is orthogonal to the X axis. One axis along the axis is defined as the Y axis, and the central axis of the fuel injection valve orthogonal to the X axis and the Y axis is defined as the Z axis.
The plurality of nozzle holes are concentric circles centered on an intersection of the X, Y, and Z axes or an arbitrary point on the Y axis within a range that allows fuel to flow into the plurality of nozzle holes. Three or more nozzle holes are arranged at equal intervals on the top, and the plurality of nozzle holes are formed such that a central axis of each nozzle hole is inclined with a predetermined nozzle hole angle with respect to the Z-axis direction. A line obtained by projecting the central axis of each nozzle hole onto the orifice plate is a line connecting a point where the central axis of each nozzle hole intersects the plane where the orifice plate is located and the center of the concentric circle. It is formed with a predetermined circumferential inclination angle.

  According to the present invention, it is possible to form a holocone-shaped spray with a more stable spray state as compared with the conventional one without increasing the number of new components, so that the fuel consumption can be reduced and the spray by atomization of the spray can be formed. As a result, it is possible to reduce the hydrocarbons in the exhaust gas and contribute to the downsizing of the catalyst of the exhaust gas treatment device. is there.

It is a longitudinal cross-sectional view of the internal combustion engine in which the fuel injection valve in embodiment of this invention is used. It is the schematic diagram which showed typically the cross section of the horizontal direction of the upper part of the internal combustion engine shown by FIG. It is the schematic diagram which showed typically the injection state by the fuel injection valve in embodiment of this invention from the side surface side. It is the schematic diagram which showed typically the injection state by the fuel injection valve in embodiment of this invention from the side which faces a nozzle part to the front. It is a longitudinal cross-sectional view of the nozzle part of the fuel injection valve in embodiment of this invention. It is a top view of the orifice plate used for the fuel injection valve in embodiment of this invention. It is the sectional view on the AA line of FIG. FIG. 8A is a longitudinal sectional view of FIG. 6, FIG. 8A is a sectional view taken along the line BB of FIG. 6, and FIG. 8B is an enlarged longitudinal sectional view of the vicinity of the injection hole. In the fuel injection valve in the embodiment of the present invention, it is a schematic diagram schematically showing a simulation result in which θ CIR is set to 90 and only the interference portion between the sprays is extracted. FIG. 6 is a schematic diagram schematically showing a simulation result in which θCIR is set to 0 and only an interference portion between sprays is extracted in the fuel injection valve according to the embodiment of the present invention. FIG. 11 is a schematic diagram schematically showing a simulation result in which, in the fuel injection valve in the embodiment of the present invention, θCIR is set to 0, the spray is set to be thicker than that in FIG. 10, and only the interference portion between the sprays is extracted. It is the schematic diagram which showed typically the measurement result of the spray state of the front-end | tip part of the holoconical spray by the fuel injection valve in embodiment of this invention. It is the schematic diagram which showed typically the measurement result of the spray state of the front-end | tip part of the holoconical spray by the conventional fuel injection valve.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 13.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, an internal combustion engine in which a fuel injection valve according to an embodiment of the present invention is used will be described with reference to FIGS. 1 and 2.
The internal combustion engine 1 shown in FIG. 1 is of a so-called port injection type, and its configuration is basically the same as that of the prior art.
The internal combustion engine 1 has a cylinder block 2, a cylinder head 3, and a piston 4. The piston 4 is slidably housed in the cylinder block 2 and a combustion chamber 5 is formed. (See FIG. 1).
An intake pipe 6 and an exhaust pipe 7 formed in the cylinder head 3 communicate with the combustion chamber 5. The cylinder head 3 includes two intake valves 8A and 8B that control the communication between the intake pipe 6 and the combustion chamber 5, and two exhaust valves 9A and 9B that control the communication between the exhaust pipe 7 and the combustion chamber 5. Are provided (see FIGS. 1 and 2).

  A fuel injection valve 20 according to the embodiment of the present invention is disposed upstream of the intake pipe 6. Such a fuel injection valve 20 has a hollow cone spray as described later toward the intake valves 8A and 8B (two-dot chain line portion in FIG. 1, two-dot chain line portion in FIG. 3, and two-dot chain line portion in FIG. 4). Is disposed at an appropriate position. Further, the cylinder head 3 is provided with a spark plug 10 so as to face the upper center portion of the combustion chamber 5 (see FIG. 1).

Next, the configuration of the nozzle portion 21 of the fuel injection valve 20 will be described with reference to FIGS.
At the end portion of the nozzle portion 21 of the fuel injection valve 20 of the present invention, an orifice plate 23 is fixed to the end portion of the valve body 22, and the ball valve 24 housed in the valve body 22 includes: By being separated from the valve seat 25 formed in the valve body 22, the fuel passes through the gap between the ball valve 24 and the valve body 22, reaches the outflow opening 26, and can flow into the injection hole 27. (See FIG. 5).
FIG. 5 is a vertical cross-sectional view of a portion where the two nozzle holes 27 are located in the diameter direction of the orifice plate 23 (see FIG. 6).

  The orifice plate 23 according to the embodiment of the present invention is formed in a lid shape, that is, a flat bottomed cylindrical shape in other words (see FIGS. 6 and 7), and its circular shape. A plurality of nozzle holes, that is, in the embodiment of the present invention, six nozzle holes 27-1 to 27-6 are formed in the bottom portion 23 a formed in a plate shape as described below. (See FIG. 6). In the following description, the description common to the nozzle holes 27-1 to 27-6 will be described as the nozzle hole 27 as appropriate.

First, for convenience of the following description, three-dimensional linear orthogonal coordinates based on the X axis, the Y axis, and the Z axis are defined. That is, for example, on the inner surface of the fuel injection valve 20 at the bottom 23a of the orifice plate 23 shown in FIG. 6, one axis along the radial direction of the orifice plate 23 is the X axis, and is orthogonal to the X axis. One axis along the radial direction of the orifice plate 23 is defined as a Y axis, and the X axis and the central axis of the fuel injection valve 20 orthogonal to the Y axis are defined as a Z axis.
In FIG. 6, it is assumed that the X axis is the left-right direction of the paper, the Y axis is the vertical direction of the paper, the Z axis is the front / back direction of the paper, and the Z axis passes through the center of the orifice plate 23. That is, in the embodiment of the present invention, the center of the orifice plate 23 coincides with the central axis of the fuel injection valve 20.

  Under such a premise, the nozzle holes 27-1 to 27-6 in the embodiment of the present invention have virtual concentric circles centered on the intersections of the X-axis, Y-axis, and Z-axis (the circles shown by alternate long and short dashed lines in FIG. (See FIG. 6). In the embodiment of the present invention, the center of the imaginary concentric circle described above coincides with the center of the orifice plate 23, but it does not necessarily need to coincide with the center of the orifice plate 23. That is, the center of the imaginary concentric circle is arbitrary on the Y axis as long as the fuel flows through the gap between the ball valve 24 and the valve body 22 and surely flows into the nozzle holes 27-1 to 27-6. It is also a good point.

Each nozzle hole 27-1 to 27-6 has a nozzle hole angle θINC and a circumferential inclination angle θCIR.
First, the nozzle hole angle θINC will be described. The nozzle hole angle θINC is an imaginary axis passing through the centers of the nozzle holes 27-1 to 27-6, that is, the center axis (the one-dot chain line in FIG. 8B). The inclination angle with respect to the Z-axis (refer to FIGS. 8A and 8B).
The nozzle hole angle θINC mainly affects the mutual distance of the sprays from the nozzle holes 27-1 to 27-6. As the nozzle hole angle θINC increases, the nozzle holes 27-1 to 27-27. Since the mutual interval between the sprays from −6 increases and interference between the sprays decreases, it is necessary to select a size that can ensure an appropriate spread of each spray.

The mutual spread of the sprays from the respective nozzle holes 27-1 to 27-6 by the nozzle hole angle θINC is finally an element for determining the spread of the entire holoconical spray in the Y-axis direction. .
Note that the diameter of the injection hole 27 varies depending on specific conditions such as the maximum injection amount of the fuel injection valve 20, and therefore an appropriate value should be selected based on tests, simulations, and the like. It is.

Next, the circumferential inclination angle θCIR will be described. The circumferential inclination angle θCIR is concentric with the point where the central axis of the nozzle holes 27-1 to 27-6 intersects the plane where the orifice plate 23 is located (FIG. 6). Is defined as an angle formed by a line formed by projecting the central axis of the nozzle holes 27-1 to 27-6 onto the orifice plate 23 with respect to a line connecting with the center of the dot-and-dash line circle) (see FIG. 6). .
The circumferential inclination angle θCIR is an element for stabilizing the holoconical spray.

  That is, the nozzle hole angle θINC is not always ensured to be formed with a stable accuracy depending on variations in the processing accuracy of the nozzle holes. In order to make the spray from each nozzle hole 27-1 to 27-6 reliably interfere for the formation of the holoconical spray, the upstream side of the spray that is unlikely to cause spray variation due to the variation of the nozzle hole angle θINC, that is, It is necessary to cause the sprays from the nozzle holes 27-1 to 27-6 to interfere with each other at a position closer to the fuel injection valve 20. Therefore, if the nozzle hole angle θINC is reduced, the spray from each nozzle hole 27-1 to 27-6 can interfere with the upstream portion, but the interference between the sprays generated from each nozzle hole 27-1 to 27-6. The area becomes large, and it becomes difficult to obtain a holoconical spray, and the spray particle size cannot be reduced.

  Therefore, the inventors of the present application, as a result of various tests and researches, added the circumferential inclination angle θCIR, and thereby increased the spray from each of the nozzle holes 27-1 to 27-6 without reducing the nozzle hole angle θINC. It has been found that a stable holoconical spray can be obtained without causing an interference area between sprays to be unnecessarily large, while causing interference in portions.

For example, FIGS. 9 to 11 schematically show the simulation results of the spray state from each injection hole in the fuel injection valve 20 in the embodiment of the present invention and the conventional fuel injection valve. The significance of providing the circumferential inclination angle θCIR will be described with reference to these drawings.
First, as a premise, in any of FIGS. 9 to 11, it is assumed that the number of nozzle holes is six and are arranged on a concentric circle at equal intervals.

  Further, in the case of FIG. 9 showing the simulation result in the fuel injection valve 20 in the embodiment of the present invention, the circumferential inclination angle θCIR is set to 90 degrees. In the conventional fuel injection valve shown in FIGS. 10 and 11, of course, unlike the embodiment of the present invention, the circumferential inclination angle θCIR is not given to the nozzle hole, and a holocone is formed only by adjusting the nozzle hole angle. It is possible.

Under such a premise, in the case of the fuel injection valve 20 according to the embodiment of the present invention in consideration of the circumferential inclination angle θCIR, the spray from each of the injection holes 27-1 to 27-6 (see FIG. 9) Compared to the case of the injection valve (see FIG. 10), it can be confirmed that the interference region of each spray extends to the upstream side (fuel injection valve side).
It is possible to widen the interference area of each spray to the upstream by making the spray from each injection hole thick without giving the circumferential inclination angle θCIR (see FIG. 11), but the volume of the interference area becomes large. (See FIG. 11) As a result, the penetration becomes large and the particle size in spraying becomes large.

By giving the circumferential inclination angle θCIR as in the fuel injection valve 20 in the embodiment of the present invention, the fuel injection valve 20 and the upstream end of the spray from each nozzle hole 27-1 to 27-6 are provided. The distance Lp (see FIG. 9) is certainly smaller than the distance LCONV1 between the upstream end of the spray from each nozzle hole and the fuel injection valve in the conventional fuel injection valve having no circumferential inclination angle θCIR. The value can be secured.
In the case of a conventional fuel injection valve (see FIG. 11) in which the spray from each nozzle hole is thick, the distance LCONV2 between the fuel injection valve and the upstream end of each spray is slightly longer than Lp. However, as described above, the volume of the interference region is increased, and a holo-cone spray cannot be obtained (see FIG. 11).

The effect of reducing the dispersion of the spray by the circumferential inclination angle θCIR as described above can be confirmed also by the measurement result of the tip portion of the holoconical spray shown in FIGS. 12 and 13.
FIG. 12 shows the spray state of the tip of the hollow cone spray by the fuel injection valve 20 in the embodiment of the present invention, and FIG. 13 shows the spray state of the tip of the hollow cone spray by the conventional fuel injection valve, respectively. An example is shown.
In both cases, the size of the nozzle hole and the size of the nozzle hole angle are the same.
In any of the drawings, the hatched portion indicates the region where the spray level (the amount of spraying) is the strongest, and the black portion indicates the region where the spray level is lower than the hatched portion. The white portion represents a portion where there is almost no spray.

In the case of a conventional fuel injection valve that does not have a circumferential inclination angle θCIR and concentrically arranges injection holes provided with only injection hole angles, as shown in FIG. There may be a state in which a plurality of portions having higher spray levels (shaded portions) are scattered in a substantially annular spray portion having a slightly lower level.
On the other hand, in the fuel injection valve 20 according to the embodiment of the present invention, as shown in FIG. 12, the tip of the holocon spray is a substantially annular spray with a high spray level represented by hatching. It can be confirmed that a part is generated. In the case of the example of FIG. 12, the spray level is lower in the inner and outer peripheral portions of the annular spray than in the hatched portion.
The above-described measurement of the spray state is generally preferable when, for example, the fuel pressure is set to 300 kPa, the internal pressure in the measurement chamber is set to a normal atmospheric pressure or lower, the temperature in the measurement chamber is set to 20 degC, and the fuel temperature is set to 20 degC. Of course, it is not necessarily limited to this condition.

As described above, in the fuel injection valve 20 according to the embodiment of the present invention, the circumferential inclination angle θCIR is given to the nozzle holes 27-1 to 27-6, as schematically shown in FIG. In the vicinity of the two intake valves 8A and 8B, a hollow cone-like spray state in which the dispersion of spray is reduced is formed.
Such a hollow cone spray is an annular spray portion at the tip thereof, and is sized so that the intake valves 8A and 8B are positioned in the vicinity of a portion approximately 180 degrees away from each other, whereby two intake valves 8A and 8B are provided. The sprayed fuel can be supplied via the.

In the above-described embodiment of the present invention, six nozzle holes 27 are provided. However, the present invention is not limited to this, and if at least three nozzle holes 27 are provided, the formation of a holoconical spray is possible. .
In the above-described embodiment of the present invention, it is assumed that the circumferential inclination angle θCIR is set to 90 degrees. However, it is not necessary to be limited to this, and for example, it is preferable to set it to 45 degrees. is there.

  Compared to the prior art, it is suitable for a fuel injection valve in which a holoconical spray with a more stable spray state is desired.

20 ... Fuel injection valve 23 ... Orifice plate 27-1 to 27-6 ... Injection hole

Claims (4)

A fuel injection valve for a port injection internal combustion engine,
On the inside surface of the fuel injection valve of the orifice plate in which a plurality of injection holes are formed, one axis along the diameter direction of the orifice plate is the X axis, and the diameter direction of the orifice plate is orthogonal to the X axis. One axis along the axis is defined as the Y axis, and the central axis of the fuel injection valve orthogonal to the X axis and the Y axis is defined as the Z axis.
The plurality of nozzle holes are concentric circles centered on an intersection of the X, Y, and Z axes or an arbitrary point on the Y axis within a range that allows fuel to flow into the plurality of nozzle holes. Three or more nozzle holes are arranged at equal intervals on the top, and the plurality of nozzle holes are formed such that a central axis of each nozzle hole is inclined with a predetermined nozzle hole angle with respect to the Z-axis direction. A line obtained by projecting the central axis of each nozzle hole onto the orifice plate is a line connecting a point where the central axis of each nozzle hole intersects the plane where the orifice plate is located and the center of the concentric circle. A fuel injection valve formed with a predetermined circumferential inclination angle.   2. The fuel injection valve according to claim 1, wherein a holocone-shaped spray can be stopped and formed at a position facing the orifice plate on a downstream side of the plurality of injection holes.   3. The spread in the Y-axis direction of a holocone-shaped spray formed at a position facing the orifice plate on the downstream side of the plurality of nozzle holes can be adjusted by the nozzle hole angle. Fuel injection valve.   The fuel injection valve according to claim 3, wherein variation in a holoconical spray formed at a position facing the orifice plate can be reduced by a circumferential inclination angle.

Images