JPH08303321A - Fuel injector - Google Patents

Abstract

PURPOSE: To increase combustion efficiency of fuel to be jetted and reduce toxic component in exhaust gas by promoting the generation of minute particles of fuel and maintaining spray pattern in good condition. CONSTITUTION: Two large and small injection holes 32A, 32B (32A', 32B') are drilled on a surface of a nozzle plate 31 obliquely, and angles θ1, θ2 are given to these injection holes 32A, 32B (32A', 32B') so that they become constant inclination angles. Consequently, it is possible to jet fuel obliquely from the injection holes 32A, 32B (32A', 32B') of the nozzle plate 31, and an injection valve (fuel injector) of two-way injection type which collides these fuels each other externally is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injector suitable for use in a fuel injection device such as an automobile engine.

[0002]

2. Description of the Related Art FIGS. 9 to 11 show a conventional fuel injector.

In the figure, 1 is an injector main body formed in a stepped cylindrical shape, 2 is a casing that constitutes the injector main body 1, and the casing 2 is a hollow outer casing in which a fuel flow port 3 is formed in the radial direction. A tubular portion 2A, a lid portion 2B formed on the axially upper end side of the outer tubular portion 2A, and a hollow tubular core portion 2 formed so as to project through the center of the lid portion 2B.
It consists of C.

Reference numeral 4 denotes a stepped cylindrical holder which constitutes the injector main body 1 together with the casing 2.
The upper end side is fitted and fixed to the lower end side of the casing 2, and a substantially U-shaped or C-shaped plate stopper 5 for restricting the opening position of the needle valve 7 described later is provided on the inner periphery of the lower end side of the injection described later. It is fitted and fixed together with the nozzle 6.

Reference numeral 6 denotes an injection nozzle formed in the shape of a hollow cylinder which is fitted and fixed to the holder 4 with the upper end side in the axial direction sandwiching the plate stopper 5, and the injection nozzle 6 extends in the axial direction. A large-diameter guide hole 6A, an injection port 6B opening at the lower end side of the injection nozzle 6, and a concave conical valve seat 6C located between the injection port 6B and the guide hole 6A. A nozzle plate 14, which will be described later, is fixed to the lower end surface 6D of the injection nozzle 6 by laser welding.

Reference numeral 7 denotes a needle valve as a valve element provided slidably in the injection nozzle 6 in the axial direction. The needle valve 7 is a valve shaft 7A sliding in the guide hole 6A and the valve. A large-diameter portion 7B formed on the upper end side of the shaft 7A and fitted into an anchor 9 to be described later, and a collar-like member formed below the large-diameter portion 7B and formed in the middle of the valve shaft 7A. 5C, and a convex conical valve portion 7D that is formed on the lower end side of the valve shaft 7A and abuts on and off the valve seat 6C.
It consists of and. A fuel flow path 8 is formed between the needle valve 7 and the injection nozzle 6.

An anchor 9, 10 fixed to the large diameter portion 7B of the needle valve 7 by means such as laser welding in a state of facing 9 to the end surface of the core portion 2C of the casing 2, is in a state of facing the anchor 9. The adjustment rod as a spring receiving member inserted in the core portion 2C is shown, and a valve spring 11 is arranged between the adjustment rod 10 and the anchor 9, and the valve spring 11 closes the needle valve 7. Always urges in the valve direction.

Reference numeral 12 denotes a solenoid as an electromagnetic actuator fitted between the outer cylinder portion 2A of the casing 2 and the core portion 2C. The solenoid 12 is excited when an injection signal is input through a terminal pin 13. The needle valve 7 is opened by sucking the anchor 9 against the spring force of the valve spring 11.

Reference numeral 14 denotes a substantially disc-shaped nozzle plate,
The nozzle plate 14 is formed by the laser welding and the injection nozzle 6
Is fixed to the lower end surface 6D of the
Four injection holes 14 located below and communicating with the injection port 6B
A, 14A, ... Are drilled at predetermined intervals.

Here, each of the injection holes 14A is formed obliquely outward from the inner surface of the nozzle plate 14 toward the outer surface thereof, as shown in FIGS.
The fuel is injected from the respective injection holes 14A in four different directions so as to spread outward. Further, each injection hole 14A is formed with the same hole diameter d.

Reference numeral 15 denotes a protector provided on the tip side of the jet nozzle 6, the protector 15 being formed of a synthetic resin material in a cylindrical shape, and surrounding the jet holes 14A of the nozzle plate 14 on the tip portion 15A side. An injection hole 15B is provided so as to surround the. Then, the protector 15
The base end side is fitted to the outer peripheral side of the injection nozzle 6, and the nozzle plate 14 is protected from the outside so that the nozzle plate 14 is not damaged by the action of an external force during transportation or assembly of the fuel injector. There is.

Reference numeral 16 is a connector provided outside the lid portion 2B of the casing 2, and 17 is a filter fitted to the outer cylinder portion 2A of the casing 2 so as to cover the fuel flow port 3.

The fuel injector according to the prior art is constructed as described above and is attached to an intake manifold (not shown) which communicates with the inside of the cylinder of the engine through an intake valve.

The fuel sent from the fuel pump is supplied into the casing 2 from the fuel flow port 3 through a fuel pipe (not shown) and a filter 17, and passes through the plate stopper 5 from the outer periphery of the anchor 9. It flows into the fuel flow path 8 between the injection nozzle 6 and the needle valve 7. And
When electric power is supplied to the solenoid 12 via the terminal pin 13 by an injection signal from a control unit (not shown), the anchor 9 together with the needle valve 7 and the valve spring 11 are provided on the lower end surface of the core portion 2C of the casing body 2. It is sucked against the spring force.

As a result, the needle valve 7 separates from the valve seat 6C and opens, and the fuel is injected from the injection port 6B of the injection nozzle 6 through the injection holes 14A into the intake manifold, so that the inside of the cylinder is closed. It is mixed with air in the combustion chamber and burned by ignition plaque. On the other hand, when power supply is stopped, the solenoid 12 is demagnetized, and the needle valve 7 is seated on the valve seat 6C by the spring force of the valve spring 11, so that fuel injection is stopped.

[0016]

By the way, in the above-mentioned conventional fuel injector, the fuel in the injector body 1 is injected into the injection holes 14 of the nozzle plate 14.
Since the fuel is injected from A in different directions, the particle size of the injected fuel is determined by the hole diameter dimension d of each injection hole 14A. For example, the particle size is about 200.
It will increase to more than μm. As a result, there is a problem in that the combustion efficiency is lowered, the lean limit is lowered, and the fuel efficiency is deteriorated.

Further, since the fuel is sprayed from each of the injection holes 14A of the nozzle plate 14 so as to spread out, the injection area becomes large, so that a part of the fuel becomes a wall film flow on the wall surface of the intake manifold. As a result, not only the combustion efficiency is lowered due to the adhesion of NOx, but also gases such as NOx are easily generated in the exhaust gas after combustion.

Therefore, the applicant of the present invention, as in the prior art shown in FIGS. 12 to 14, has the upper and lower injection holes 21A and 21B located on the left side of the central portion of the nozzle plate 20 and the right side of the central portion. Upper and lower injection holes 21A ', 21B' are provided respectively, and the injection holes 21A, 21B (21A ', 2) are provided.
1B ') with the same hole diameter d, and the fuel plate was obliquely drilled in the nozzle plate 20 so as to collide with each other in the directions A and B shown in FIG.

In this prior art, the injection hole 21
The fuel injected from A, 21B (21A ', 21B') is made to collide with each other in the directions of arrows A and B, so that the fuel is made into a spray having a finer particle diameter by the collision force generated at this time. . Further, it is possible to prevent the fuel from spreading outward from the respective injection holes 21A and 21B and being injected by this collision, thereby reducing the injection area of the fuel.

However, even in such a prior art,
There is an unsolved problem that the fuel from the injection holes 21A and 21B is merely colliding with each other and the atomization of the fuel cannot be sufficiently achieved.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention can effectively promote atomization of fuel and can maintain a good spray pattern (injection area). An object of the present invention is to provide a fuel injector capable of increasing combustion efficiency and reliably reducing harmful components in exhaust gas.

[0022]

In order to solve the above-mentioned problems, the present invention opens and closes an injector main body, an injection nozzle provided on the tip side of the injector main body, and an injection port of the injection nozzle. The present invention is applied to a fuel injector including a valve body and a nozzle plate which is provided in the injection nozzle so as to cover the injection port of the injection nozzle and has a plurality of small-diameter injection holes.

The feature of the configuration adopted by the invention of claim 1 is that the fuel injected from the injection nozzle to the outside through the injection holes collides with the injection holes of the nozzle plate. The nozzle plate is formed with a constant inclination angle, and the diameters of the respective injection holes are different from each other.

The feature of the configuration adopted by the invention of claim 2 is that a total of four sets of two injection holes each having a large and small hole diameter are formed in the nozzle plate, and the respective injection holes are formed. Is configured to inject the fuel in different directions for each group.

Furthermore, the feature of the structure adopted by the invention of claim 3 is that the nozzle plate has a first large hole diameter.
Of the injection holes and the second and second injection holes having a smaller diameter than the first injection holes.
A third injection hole is provided, and the first, second and third injection holes are formed obliquely with respect to the surface of the nozzle plate so that fuels from the injection nozzle collide with each other outside. It is configured to do.

[0026]

With the above construction, in the invention described in claim 1,
Since the fuel injected from the small-diameter injection hole has a small hole diameter, the injection speed can be made faster, so that the fuel injected from each injection hole can collide with each other with a larger collision force. Thus, the atomized particle size of the fuel injected from each injection hole can be surely reduced. On the other hand, since the fuel injected from the large-diameter injection hole has a large hole diameter, the spray pattern can be made larger, so that the collision probability of the fuel injected from each injection hole can be increased, and the mutual injection probability can be increased. The injected fuel can be reliably collided.

In this case, as in the second aspect of the invention, a total of four sets of two injection holes each having a large diameter and a small diameter are formed in the nozzle plate, and each of the injection holes is formed. By configuring the groups to inject the fuel in different directions from each other, the fuel injected from the injection holes can more reliably collide with each group and be injected in two directions.

Further, as in the invention described in claim 3, the nozzle plate has a first injection hole having a large hole diameter, and second and third injection holes having a hole diameter smaller than the first injection hole. And the first, second and third injection holes are formed obliquely with respect to the surface of the nozzle plate so that the fuels from the injection nozzles collide with each other outside. With this, a larger collision force can be exerted on the fuel injected from each injection hole, and the atomized particle size of the fuel can be further reduced.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the embodiment, the same components as those of the prior art shown in FIGS. 9 to 11 described above are designated by the same reference numerals, and the description thereof will be omitted.

1 to 4 show a first embodiment of the present invention.

In the figure, reference numeral 31 denotes a substantially disc-shaped nozzle plate, which is fixed to the lower end surface 6D of the injection nozzle 6 similarly to the nozzle plate 14 shown in the prior art, but at the center thereof. Each of the below-mentioned injection holes 32
A, 32A ', 32B and 32B' are provided.

Reference numerals 32A, 32B (32A ', 32B') denote large and small injection holes which are located on the left side (right side) of the central portion of the nozzle plate 31 and are formed obliquely in the plate thickness direction, respectively. Each injection hole 32A, 32B (32A ', 32
B ') has hole diameters d1 and d2 (d1> d), respectively.
2) and is formed obliquely with respect to the surface of the nozzle plate 31 at angles θ2 and θ3 described later.

Here, each of the injection holes 32A, 32B (32
As shown in FIGS. 2 and 3, center points PA and PB of A ', 32B') are located on a virtual circle R concentric with the center O of the nozzle plate 31, respectively.
The reference line L1 passing through the center O and the reference line L2 passing through the center point PB and the point O form an angle (2.times..theta.1) with each other, and the injection holes 32A and 32B are positioned with respect to the nozzle plate 31 by the angle .theta.1. ing.

The injection holes 32A and 32B are tangential lines mr1 and mr2 of the virtual circle R on the plane of the nozzle plate 31.
Line segments m1 and m inclined at an angle of .theta.2 with respect to the center points PA and PB of the injection holes 32A and 32B, respectively.
2, the central axis M1 of the injection holes 32A, 32B,
M2 is the line segments m1 and m2 on the surface of the nozzle plate 31.
With respect to each other, they are inclined at an angle of θ3. The respective injection holes 32A and 32B have their respective angles θ2,
The angles of inclination of the central axes M1 and M2 are determined by θ3, respectively, and the fuel injection directions (arrows C and D) from the injection holes 32A and 32B are determined by the angles θ1, θ2 and θ3.

The injection holes 32A 'and 32B' are also formed obliquely at the same angles .theta.2 and .theta.3 as the injection holes 32A and 32B, and the fuel injection direction (arrow C ', arrow C', shown in FIG.
D ') is the injection direction of the injection holes 32A, 32B (arrow C,
D) is substantially opposite to that of 180 °.

The fuel injector according to this embodiment has the above-mentioned structure, and its basic operation is not different from that of the prior art.

Therefore, in this embodiment, the nozzle plate 3
4 large and small injection holes 32 diagonally to the surface of 1
A, 32A ', 32B, 32B' are bored, and the respective injection holes 32A, 32B (32A ', 32B') are formed at angles .theta.1, .theta.
2 and θ3 are used to position the nozzle plate 31 relative to the nozzle plate 31 and determine the inclination direction, so that the fuel is injected from the injection holes 32A, 32B (32A ', 32B') at the arrows C, D (arrow C It is possible to inject in two directions obliquely to the directions ', D'), and the following effects can be obtained.

That is, with the above structure, the injection hole 32 having a small diameter is provided.
The fuel injected from B (32B ') has a hole diameter d2 (d2 <
Since d1) is small, the injection hole 32B (32
The fuel from B ') can be injected at a higher speed, and the fuel injected from the large-diameter injection holes 32A (32A') can be made to collide with a larger collision force. 32A, 32B (32
It is possible to reliably reduce the atomized particle size of the fuel injected from A ', 32B').

On the other hand, since the fuel injected from the large-diameter injection hole 32A (32A ') has a large hole diameter dimension d1 (d1> d2), the spray pattern can be increased. 32A, 32B (32
The collision probability of the fuel injected from A ', 32B') can be increased, and the injected fuels can reliably collide with each other.

Then, each injection hole 3 of the nozzle plate 31
The fuel injected from 2A, 32B (32A ', 32B') was measured by a laser particle size measuring device at a position separated from the nozzle plate 31 by a certain dimension, and the characteristics shown in FIG. 4 were obtained.

Here, the horizontal axis represents the injection holes 32A (32
A ') hole diameter ratio (d) to the injection hole 32B (32B')
1 / d2) and the vertical axis represents the atomized particle size of the fuel. The characteristic line in FIG. 4 indicates the injection holes 32A, 32B.
The angles θ1, θ2, and θ3 of (32A ', 32B') are, for example, 32 ° 54 'for the angle θ1 and 7 ° 30' for the angle θ2.
And shows the case where the angle θ3 is 68 ° 40 '.

As a result, the hole diameter ratio (d1 / d2) of the injection holes 32A (32A ') to the injection holes 32B (32B').
Is gradually increased to 1.0 or more, the atomized particle size of the fuel is gradually decreased, and the hole diameter ratio (d1 / d2) is 1.3 or more and 1.6 or less It was confirmed that the particle size can be surely reduced to 170 μm or less, and in particular, the atomized particle size of the fuel can be atomized to 90 μm or less by setting the pore size ratio within the range of 1.4 to 1.5. Further, the angle θ1 is in the range of 30 ° to 35 °, and the angle θ2 is
It has been confirmed that the atomization of the fuel can be promoted by setting the value within the range of 65 ° to 70 °.

Therefore, according to this embodiment, the nozzle plate 31 has a total of four injection holes 32A, 32B (32A ', 32A',
In a two-way injection valve (fuel injector) having a bore 32B '), the injection holes 32A, 32B (32
A ', 32B') has a pore diameter ratio (d1 / d2) of 1.3 to
The injection holes 32A, 32B (32A ', 32B') are set within the range of 1.6, preferably 1.4 to 1.5.
It is possible to reliably promote atomization of the fuel injected from the fuel, and it is possible to effectively prevent the fuel from adhering to the intake manifold, the wall surface of the combustion chamber, and the like, which results in the combustion efficiency of the fuel and the fuel consumption (fuel consumption). The amount) can be reliably improved, and harmful components (NOx, etc.) contained in the exhaust gas can be effectively reduced.

Next, FIGS. 5 to 8 show a second embodiment of the present invention. In this embodiment, a first injection hole 42A having a large hole diameter d3 is formed in the central portion of the nozzle plate 41, and the first injection hole 42A. Second with smaller hole diameter d4 (d4 <d3) than the injection hole 42A
The injection holes 42B and 42B 'are obliquely formed with a constant inclination angle.

Here, each of the injection holes 42A and 42B has a center O of the nozzle plate 41 as shown in FIGS.
The center point QA of the injection hole 42A is arranged on a virtual circle S concentric with the reference line L passing through the center O of the nozzle plate 41.
Located on 3 In addition, the center point Q of each injection hole 42B
B is the angle θ4 from the reference line L3 on the side opposite to the injection hole 42A.
It is oriented on a line segment n (passing through the center point O) inclined by an amount. The central axis N1 of the injection hole 42A is the reference line L3.
The inclination angle is set to an angle θ5 with respect to (on the plane of the nozzle plate 41), and the central axis N2 of each injection hole 42B is the same angle θ5 with respect to the line segment n (on the plane of the nozzle plate 41). Is set to.

Thus, also in this embodiment having such a structure, the fuel injected from the respective injection holes 42A and 42B can be made to collide with each other in the directions G and H shown in FIG. The atomization of the fuel can be achieved almost in the same manner as in the embodiment, but particularly in this embodiment, the nozzle plate 4 is used.
Since the injection hole 42A having a large hole diameter d3 and the respective injection holes 42B having a small hole diameter d4 are formed in 1 to be used as a one-way injection valve (fuel injector), the injection from the injection holes 42A, 42B is performed. A large impact force can be applied to the fuel, which can further promote atomization of the fuel.

Further, the angle θ4 of each injection hole 42B is set to 30
As shown in FIG. 8, the atomization characteristics (atomization characteristics for the angle θ5) of the fuel when the temperature is changed to °, 35 °, 40 ° and 45 ° are shown in FIG. / D4) is set to 1.5, angle θ4
Is 30 °, the characteristic line 4 shown by the solid line in FIG.
3, the angle θ5 of each injection hole 42A, 42B is 45 °.
By setting the angle within the range of up to 55 °, the particle size of the fuel is 10
It was confirmed that the size could be reduced to about 0 μm. Even when the angle θ4 is set to 35 °, the angle θ5 of each of the injection holes 42A and 42B is set within the range of 45 ° to 55 ° as shown by the characteristic line 44 shown by the dotted line in FIG.
It was confirmed that the particle size of the fuel could be reduced to about 100 μm.

On the other hand, when the angle θ4 is set to 40 °, the angle θ becomes as shown by the characteristic line 45 indicated by the chain double-dashed line in FIG.
When 5 is before and after 55 °, the particle size of the fuel can be reduced to about 150 μm, and when the angle θ4 is set to 45 °, the angle θ5 is 45 ° as shown by the characteristic line 46 shown by the one-dot chain line.
Before and after, the particle size can be reduced to about 100 μm,
It was confirmed that when the angle θ 5 was increased, the particle size also increased accordingly.

Further, as a result of examining the spray pattern in which the fuel is injected from the injection holes 42A and 42B, the angle θ4 is set to 30.
By setting the angle θ5 to be in the range of ° to 35 ° and the angle θ5 to be 45 ° to 58 °, and preferably the angle θ5 to be before and after 55 °, it is possible to reduce the injection area and maintain the spray pattern in a good condition. It was confirmed that harmful components can be reduced.

In each of the above embodiments, the case where four or three injection holes are formed in the nozzle plate 31 (41) has been described as an example, but the present invention is not limited to this, and for example, 2 Large and small injection holes having different hole diameters may be formed in the nozzle plate, and two sets of the injection holes 42A and 42B described in the second embodiment are provided so that the nozzle plate has a total size. You may make it provide 6 injection holes.

[0051]

As described in detail above, according to the present invention, as described in claim 1, the respective injection holes of the nozzle plate are
The nozzle plate is formed with a constant inclination angle so that the fuel injected from the injection nozzle to the outside through the injection holes collides, and the diameter of each injection hole is large.
Since the holes have different small diameters, the injected fuel from each injection hole can be made to collide with a higher collision probability and with a larger collision force, which can effectively promote atomization of the fuel. At the same time, the injection area of the fuel can be favorably maintained, and fuel efficiency of the fuel and reduction of harmful components in the exhaust gas can be reliably achieved.

Further, in the invention described in claim 2, 2 pieces 1
Fuel can be injected from each of a total of four injection holes in a group so that the injected fuel can collide with each other with certainty, and atomized fuel can be effectively injected in two different directions. It is possible to improve the fuel efficiency performance of a 4-valve engine or the like.

Further, in the invention described in claim 3, the fuel injected from the three injection holes can be made to collide with each other with a larger collision force, and the atomization of the fuel can be surely promoted. At the same time, the fuel spray pattern (injection area) can be favorably maintained, and harmful components in the exhaust gas can be effectively reduced.

[Brief description of drawings]

FIG. 1 is a plan view showing a nozzle plate of a fuel injector according to a first embodiment of the present invention.

FIG. 2 is a plan view showing an enlarged main part in FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is a characteristic diagram showing a relationship between a hole diameter ratio of each injection hole and a fuel particle diameter.

FIG. 5 is a plan view similar to FIG. 1, showing a second embodiment of the present invention.

FIG. 6 is a plan view showing an enlarged main part in FIG.

FIG. 7 is a sectional view taken along line VII-VII in FIG.

FIG. 8 is a characteristic diagram showing the relationship between the inclination angle of each injection hole and the particle size of fuel.

FIG. 9 is a vertical sectional view showing a fuel injector according to the prior art.

10 is an enlarged plan view showing the nozzle plate in FIG. 9. FIG.

11 is a sectional view taken along the line XI-XI in FIG.

FIG. 12 is a plan view showing a nozzle plate according to the prior art.

FIG. 13 is an enlarged plan view showing a main part in FIG.

14 is a cross-sectional view taken along arrow XIV-XIV in FIG.

[Explanation of symbols]

1 Injector body 6 Injection nozzle 7 Needle valve (valve body) 31,41 Nozzle plate 32A, 32A ', 32B, 32B', 42A, 42B
Injection holes d1, d2, d3, d4 Hole diameters θ1, θ2, θ3, θ4, θ5 Angle (tilt angle)

Claims (3)

[Claims] 1. An injector main body, an injection nozzle provided at a tip side of the injector main body, a valve body for opening and closing an injection port of the injection nozzle, and the injection so as to cover the injection port of the injection nozzle. In a fuel injector including a nozzle plate provided in a nozzle and having a plurality of small-diameter injection holes formed therein, each injection hole of the nozzle plate is
The nozzle plate is formed with a constant inclination angle so that the fuel injected from the injection nozzle to the outside through the injection holes collides, and the diameter of each injection hole is different between large and small. Fuel injector characterized by having a hole diameter. 2. The nozzle plate has a large size,
2. The fuel injector according to claim 1, wherein two sets of two injection holes each having a small hole diameter are provided in total, and each injection hole is configured to inject the fuel in different directions. 3. The nozzle plate is provided with a first injection hole having a large hole diameter and second and third injection holes having a hole diameter smaller than that of the first injection hole. The fuel injector according to claim 1, wherein the third injection hole is formed obliquely with respect to a surface of the nozzle plate so that fuels from the injection nozzle collide with each other outside.