JPH0444845Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a fuel injection valve having a plurality of nozzle holes.

(Prior art) As optimization of engine control is progressing in recent years, precise control of fuel supply amount is required.In order to meet this demand, fuel injection Valves are frequently used.

By the way, in engines with multiple intake ports in each cylinder to improve intake efficiency, one fuel injector is generally arranged so as to face one intake port. There is a problem with poor air utilization. On the other hand, it is possible to arrange a fuel injection valve for each intake port, but since this is disadvantageous in terms of cost, one fuel injection valve is provided with multiple nozzle holes, and each nozzle is connected to each intake port. A system that injects fuel toward the target has been proposed.

Generally, this type of fuel injection valve is provided with a distribution chamber 2 downstream of a metering orifice 1, as shown in FIG. 3, 3, and is injected from each nozzle hole 3 toward each intake port.

In this way, the distribution chamber 2 provided in the fuel injection valve
This has the function of evenly distributing the fuel from the metering orifice 1 to the respective nozzle holes 3, 3, but it is also provided for manufacturing reasons.

That is, since the nozzle hole 3 is drilled from the tip side of the fuel injection valve, the above-mentioned distribution chamber 2 provides a place for the tip of the drill to escape when drilling the nozzle hole 3. As such, it is necessary.

(Problems to be solved by the invention) However, the distribution chamber acts as a dead volume located downstream of the metering orifice.

Therefore, the presence of the distribution chamber gives an undefined error between the amount of fuel measured by the metering orifice and the amount of fuel actually injected from the nozzle hole, and also increases the amount of fuel that has passed through the metering orifice. Since the fuel is injected from each nozzle hole after it has accumulated in the depleted volume, there is a difference in injection timing, that is, a lack of transient response, making it impossible to meet the demands for precise control of fuel injection.

The present invention was developed in consideration of the above-mentioned circumstances, and its technical problem is that when drilling multiple nozzle holes, at least the minimum necessary An object of the present invention is to provide a fuel injection valve that improves the accuracy of the fuel injection amount and the transient response of fuel injection while recognizing the existence of a distribution chamber that is required to have a certain volume.

(Means for Solving the Problems) In order to achieve the above object, the present invention has the following configuration. That is, a needle valve for regulating fuel injection, a metering orifice provided downstream of the needle valve, and a metering orifice provided only downstream of the metering orifice, extending coaxially with the metering orifice and opening facing the metering orifice. and a distribution chamber for distributing the fuel that has passed through the metering orifice to a plurality of nozzle holes, the fuel injection valve for an engine for injecting fuel into an intake passage of the engine, wherein the tip of the needle valve is connected to the The needle valve extends deep into the distribution chamber, an umbrella part is formed at the tip of the needle valve, and the direction in which the umbrella part extends is set to face the nozzle hole.

(Example) FIG. 7 shows an example in which the fuel injection valve 10 of the example is applied to an engine having two intake ports.

In Fig. 7, reference numeral 11 indicates the engine body, and two intake ports 14, 14 are opened for each cylinder 13 in the cylinder head 12 of the engine body 11, and a branch pipe 15 of the intake manifold is connected to the cylinder head 12 of the engine body 11. . Two independent intake passages 17, 17 are defined in the branch pipe 15 by a partition wall 16, and each independent intake passage 17 is communicated with each intake port 14, respectively. Fuel is supplied into each cylinder 13 by fuel injection from a fuel injection valve 10 mounted on an intake manifold 15.

The fuel injection valve 10 is disposed across a partition wall 18 that partitions the intake ports 14 , 14 .
As shown in FIG.
Two injection holes 21, 21 are provided with injection directions oriented in the direction.

FIG. 1 shows the overall structure of the fuel injection valve 10, in which an oil passage 23 is formed in the main body 22.
A filter 25 is attached to the inlet 24 of the oil passage 23, and a needle holder 26 is tightly fitted on the downstream side of the oil passage 23. The needle holder 26 includes a second oil passage 27 communicating with the oil passage 23 of the main body 22, a metering orifice 28 formed at the downstream end of the second oil passage 27, and a metering orifice 28 immediately upstream of the metering orifice 28. A shaped seat surface 29 is provided and a needle valve 30 is housed within the second oil passage 27 .

The needle valve 30 is provided with a tapered portion 31, and the tapered portion 31 and the seat surface 29 constitute a valve body that opens and closes the second oil passage 27.

That is, the main body 22 includes an electromagnetic solenoid 32.
a core 33 that is accommodated in the oil passage 23 of the main body 22 and moves upstream when the electromagnetic solenoid 32 is excited; a stopper 34 that restricts the amount of movement of the core 33 upstream; A return spring 35 is provided that biases the flow in the downstream direction. The upstream end of the needle valve 30 is integrally connected to a core 33, and the tapered portion 31 of the needle valve 30 is a movable valve body that can be moved into and out of the seat surface 29. In other words, by energizing the electromagnetic solenoid 32, the needle valve 30
is lifted by a certain amount, and the tapered portion 31 is raised to the seat surface 29.
The second oil passage 27 is opened by separating from the oil passage 27, and the electromagnetic solenoid 32 is demagnetized, so that the tapered part 31 is seated on the seat surface 29 by the biasing force of the return spring 35. ,
The second oil passage 27 is blocked. In FIG. 1, the reference numeral 36 indicates a connector.

As shown in FIG.
7 is formed. A distribution chamber 38 is provided in this outer cylinder 37 concentrically with the metering orifice 28, and the two nozzle holes 21, 21 are opened from the distribution chamber 38 to the outside through the outer cylinder 37. . This distribution chamber 38 is connected to the needle holder 26 of the outer cylinder 37.
The nozzle holes 21, 21 are formed by inserting a drill from the insertion port into the outer cylinder 37, and the nozzle holes 21, 21 are formed by drilling from the outside of the outer cylinder 37, that is, from the distal end side of the outer cylinder 37 toward the distribution chamber 38. established,
When drilling the nozzle hole 21, the distribution chamber 38 provides a place for the tip of the drill to escape.

For this reason, the distribution chamber 38 necessarily requires a certain amount of volume in order to form the nozzle holes 21. Therefore, the metering orifice 2
8, the fuel first enters into the distribution chamber 38,
Thereafter, it is distributed and injected from the nozzle holes 21, 21 toward the respective intake ports 14, 14.

The distal end of the needle valve 30 described above is extended into the distribution chamber 38 which performs this function. That is, the needle valve 30 is provided at its distal end with an extension 40 that passes through the metering orifice 28 and extends deep into the distribution chamber 38 .

The extension 40 extends concentrically with the metering orifice 28 and has a base 4 extending through the metering orifice 28.
1 has a cylindrical shape with a smaller diameter than the metering orifice 28, and there is a certain distance between the metering orifice 28 and the metering orifice 28.
is formed. The extension part 40 is formed so that the diameter of the extension part 40 is gradually reduced following the base part 41 in the direction in which it extends, and the diameter of the extension part 40 is gradually enlarged as it goes toward the distal end part. An umbrella section 42 is provided. The umbrella portion 42 projects outward in the radial direction at the tip of the needle valve 30, and the projecting angle α of the umbrella portion 42, that is, the included angle of the tapered surface forming the outer circumferential surface of the umbrella portion 42 is equal to the nozzle hole. It is made equal to the included angle β between the center lines of 21 and 21. In addition, in FIG. 2, the projecting angle α of the umbrella portion 42 is shown to be larger than the included angle β between the center lines of the nozzle holes 21, 21, but this is because the umbrella portion 4
This is based on the drawing purpose of emphasizing the overhang of No. 2.

With this configuration, when the needle valve 30 is lifted and fuel pressurized to a predetermined pressure flows into the metering orifice 28, the fuel is guided to the extension 40 of the needle valve 30 and distributed. Room 3
8. At this time, since the extension portion 40 of the needle valve 30 extends into the distribution chamber 38, the substantial volume of the distribution chamber 38 is small, so that the fuel flowing into the distribution chamber 38 is
It immediately flows into the nozzle holes 21, 21, and each nozzle hole 2
It will be injected from 1. Similarly, when the needle valve 30 is closed, since there is only a small amount of liquid in the distribution chamber 38, fuel injection is immediately stopped when the needle valve 30 is closed.

From this, the error between the fuel injection measured by the metering orifice 28 and the actual injection amount is
8 is reduced by the amount that is substantially reduced in volume by the extension portion 40 of the needle valve 30, and the accuracy in controlling the injection amount can be improved, and the transient response of fuel injection can be improved.

Additionally, in this embodiment, the extension 40 extends aligned with the centerline of the metering orifice 28 so that the fuel exiting the metering orifice 28
The fuel is evenly distributed and guided by the outer circumferential surface of the extension portion 40 and flows into each nozzle hole 21, thereby improving the uniform distribution of the fuel. Furthermore, the presence of the umbrella 42 allows the fuel to flow through the bottom 38 of the distribution chamber 38.
Since the fuel is distributed to each nozzle hole 21 without hitting the nozzle a, the even distribution of the fuel can be further improved. Furthermore, since the projecting angle α of the umbrella portion 42 is made equal to the included angle β between the center lines of the nozzle holes 21, 21, the fuel distributed to each nozzle hole 21 by the tapered surface of the umbrella portion 42 is , the fuel is oriented in the extending direction of the nozzle hole 21, which can reduce the formation of oil droplets due to the fuel colliding with the inner wall surface of the nozzle hole 21, and improve the atomization state of the fuel injected from the nozzle hole 21. can be maintained at a high level.

3 to 6 show modified examples of the present invention, and elements that are the same as those in the first embodiment will be given the same reference numerals, and their explanation will be omitted as appropriate, and the features of each modified example will be explained. .

FIG. 3 shows a second embodiment, in which an umbrella portion 42 is provided at the tip of the extension portion 40 as in the first embodiment.
is provided, and the amount of radially outward protrusion l1 of the umbrella portion 42 is determined by the diameter l2 of the bottom portion 38a of the distribution chamber 38.
is the same as or larger (l1≧l2). This has the advantage that the fuel flowing into the distribution chamber 38 does not come into direct contact with the bottom portion 38a, thereby reducing turbulence in the flow of fuel. Of course, as in the first embodiment, the umbrella part 42
It is preferable to make the protrusion angle α as equal as possible to the included angle part β of the center line of the nozzle holes 21, 21 because this can improve the directivity of the fuel.

Figures 4 and 5 show the third embodiment,
The assist air introduction passages 44, 44 are in the distribution chamber 38.
The direction in which each introduction passage 44 extends is oriented in the tangential direction of the inner wall surface constituting the distribution chamber 38 . From this, a swirl S is generated in the distribution chamber 38 by the assist air sent into the distribution chamber 38 from the introduction passage 44, and the fuel is vaporized and
It is possible to promote atomization and the outflow of fuel to the nozzle hole 21, which has the advantage that the transient response of the fuel injection valve can be further improved.

FIG. 6 shows a fourth embodiment. In this embodiment, a sleeve 45 in which a distribution chamber 38 and nozzle holes 21, 21 are formed is separately provided.
is configured to be fitted onto the outer cylinder 37.

In this embodiment, the above-mentioned distribution chamber 38 was conventionally formed in the outer cylinder 37 that covered the needle holder 26, so it was difficult to align the center of the distribution chamber 38 with the center of the metering orifice 28 due to actual manufacturing reasons. However, in order to form the distribution chamber 38 in the outer cylinder 37, it was necessary to insert the drill deep into the outer cylinder 37 from the insertion opening side of the needle holder 26, which made it extremely difficult to form the distribution chamber 38 in the outer cylinder 37. This was done in consideration of the fact that accurate centering was nearly impossible due to runout.

According to this embodiment, in the conventional case, individual differences tend to occur in alignment between the center of the metering orifice 28 and the center of the distribution chamber 38, and the distribution of fuel to each nozzle hole 21 is uneven, that is, the fuel is not evenly distributed. The problem that the distribution of the liquid is obstructed can be solved by separately providing a distribution chamber 38 in the sleeve.

(Effect of the invention) As is clear from the above explanation, according to the invention, the substantial volume of the distribution chamber as a dead volume existing downstream of the metering orifice is reduced by the tip of the needle valve extending into the distribution chamber. Since the amount is small, the accuracy of the fuel injection amount and the transient response of the fuel injection can be improved.

Furthermore, since the umbrella portion is formed at the tip of the needle valve, this is preferable in terms of further reducing the volume of the distribution chamber, compared to a case where the tip of the needle valve is simply formed into a tapered shape. .

Further, by using the above-mentioned umbrella part, it is possible to improve the uniform distribution of fuel from the distribution chamber to the plurality of nozzle holes, and it is also possible to improve the promotion of atomization of the fuel.

[Brief explanation of the drawing]

FIG. 1 is an overall vertical sectional view of the embodiment, and FIG. 2 is a
3 is a vertical sectional view of the main part of the first embodiment, FIG. 4 is a longitudinal sectional view of the main part of the third embodiment, and FIG. 5 is a longitudinal sectional view of the main part of the third embodiment. 6 is a cross-sectional view showing the assist air introduction passage in the embodiment, FIG. 6 is an exploded vertical sectional view of a main part of the fourth embodiment, FIG. 7 is a schematic diagram showing an example of application to an engine having two intake ports, FIG. 8 is a sectional view showing a conventional example. 10... Fuel injection valve, 11... Engine body,
28...Measuring orifice, 20...Needle valve,
38... distribution chamber, 40... extension of the needle valve.

Claims (1)

[Scope of Claim for Utility Model Registration] A needle valve for regulating fuel injection, a metering orifice provided downstream of the needle valve, and a metering orifice provided only downstream of the metering orifice and extending coaxially with the metering orifice. A fuel injection valve for an engine for injecting fuel into an intake passage of the engine, the fuel injection valve having: a distribution chamber that is opened facing the orifice and distributes the fuel that has passed through the metering orifice to a plurality of nozzle holes; A tip of the needle valve extends to a deep part of the distribution chamber, an umbrella is formed at the tip of the needle valve, and an extending direction of the umbrella is set to face the injection hole. An engine fuel injection valve featuring: