JP4127703B2 - Fuel injection device - Google Patents

Description

  The present invention relates to a fuel injection device used for an internal combustion engine, and more particularly to a fuel injection device capable of improving atomization and improving the shape and injection direction of fuel spray.

  In recent years, exhaust gas regulations for automobiles and the like have been strengthened, and it has been required to create various shapes and directions of the fuel spray injected by the fuel injection device and promote atomization of the spray. Is required. In particular, various investigations have been made on atomization of fuel spray. In conventional fuel injection devices, slots are formed radially on the valve seat side outlet end face of the injection port or on the downstream side of the valve body with respect to the valve body axis. There was something that was forming.

  In this fuel injection device, since the spray wraps around the end face of the valve body, it is not a hollow cone spray having a large spray angle peculiar to a poppet valve, but a solid spray that suppresses the spray angle and is suitable for mixing with air. It is formed. Further, when the spray wraps around the end face of the valve body, the distance traveled by the spray per unit time is suppressed and atomization by mixing with air is promoted (see Patent Document 1).

JP-A-11-193734

  The conventional fuel injection device is configured as described above, and there is a problem that it is difficult for the slot provided in the injection port to control the spray shape and the injection direction independently. Further, since the slot is provided on the downstream side of the seat portion where the valve body comes into contact with the valve seat, fuel is accumulated in the slot after the fuel injection is completed. When the fuel injection device is used for intake pipe injection, there is a problem that the air-fuel ratio fluctuates due to the fuel adhering to the valve body falling as droplets.

  The present invention has been made to solve the above-described problems. In a fuel injection device for a gasoline engine, the fuel is prevented from adhering to the outlet of the injection port, and various spray shapes and injection directions are formed. An object of the present invention is to provide a fuel injection device that can improve the atomization of the spray.

The fuel injection device according to the present invention has a valve body provided with a valve seat, and a valve body that is separated from and in contact with the valve seat, and is an outer valve opening type that opens when the valve body moves downstream. It is one, together with the valve body provided with a plate having a downstream injection hole of the seat portion in contact with the valve seat, provided with a cavity communicating with the opening time of the injection hole between the end face of the plate and the valve body, further sheet When the flow passage cross-sectional area of the part is S1, the flow passage cross-sectional area of the cavity is S2, and the flow passage cross-sectional area of the injection hole is S3, the relationship of S1>S2> S3 is satisfied.

According to the fuel injection device of the present invention, the valve body provided with the valve seat and the valve body that is separated from and in contact with the valve seat, the outer valve that opens when the valve body moves downstream. A plate having an injection hole on the downstream side of the seat portion where the valve body abuts on the valve seat, and a cavity communicating with the injection hole at the time of valve opening is provided between the plate and the end face of the valve body, Further, when the flow path cross-sectional area of the sheet portion is S1, the flow path cross-sectional area of the cavity is S2, and the flow path cross-sectional area of the injection hole is S3, it is configured to satisfy the relationship of S1>S2> S3. The spray shape and the injection direction can be formed, atomization of the fuel spray can be promoted, and the fuel can be prevented from adhering to the injection hole outlet. Furthermore, even if the valve body lift amount varies, there is no effect on the flow path cross-sectional area S2 and the flow path cross-sectional area S3, and the flow characteristics and spray characteristics are less likely to vary.

Embodiment 1 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a fuel injection device according to Embodiment 1 of the present invention, FIGS. 2 and 3 are cross-sectional views showing a tip portion, FIG. 2 shows a valve closing state, and FIG. Indicates the state.
The fuel injection device according to the present invention is provided with a valve device 1, which is composed of a valve body 2 and a valve body 3.

  The valve body 2 has a guide portion 2a, and the guide portion 2a is provided with a two-plane flat portion 2b. The fuel flows through the gap between the inner diameter portion 3a of the valve body 3 and the valve body 2 and the gap between the inner diameter portion 3a and the flat surface portion 2b. A valve body seat portion 2c is provided at the tip of the valve body 2, and the valve body seat portion 2c and the valve seat 3b provided on the valve body 3 are in contact with each other at the seat portion 3c.

  The spring 4 is for urging the valve body 2 in the valve closing direction. An armature 5 is attached to the valve body 2, and a core 6 is disposed to face the armature 5. A solenoid device is configured by winding an electromagnetic coil 8 in the bobbin 7.

  A plate 9 is provided at the tip of the fuel injection device, and the plate 9 is provided with a convex portion 9a facing the valve element end surface 2d. The plate 9 is provided with a plurality of injection holes 9b inclined at a predetermined angle in a direction away from the axis of the valve device 1. By opening the valve, the valve body end surface 2d comes into contact with the convex portion 9a, the cavity 10 is formed between the valve body end surface 2d and the plate 9, and the injection hole 9b and the cavity 10 communicate with each other.

  In the fuel injection device configured as described above, a magnetic circuit is formed by supplying a current to the electromagnetic coil 8, and the valve body 2 moves downstream by attracting the armature 5 to the core 6 to inject the fuel. Fuel is injected from the port 9b into the internal combustion engine. As shown in FIG. 3, the movement of the valve body 2 is terminated when the valve body end surface 2d abuts against the convex portion 9a. When the current is cut off, the valve body 2 moves upstream by the restoring force of the spring 4, and the fuel injection ends.

  FIG. 4 is an enlarged cross-sectional view showing the plate 9 portion. In the cavity 10, the fuel flow P flowing in the direction toward the center of the valve device 1 is accelerated, and the injection hole 9 b is separated from the axis of the valve device 1. Since it is inclined at a predetermined angle in the direction, separation of the fuel flow is enhanced at the injection hole inlet 9c, and atomization of the fuel spray is promoted.

  As described above, in the present embodiment, since a plurality of injection holes 9b are provided in the plate 9 and communicated with the cavity 10, various spray shapes and injection directions can be formed, and fuel spray Atomization can be promoted. Furthermore, it is possible to suppress the fuel from adhering to the outlet of the injection hole.

Embodiment 2. FIG.
FIG. 5 is a cross-sectional view showing a tip portion of a fuel injection device according to Embodiment 2 of the present invention.
In the first embodiment, the case where the projection 9a is provided on the plate 9 has been described. However, in the present embodiment, the projection 2e is provided on the distal end surface of the valve body 2 to form the cavity 10. Is.
By configuring as described above, the same operation as in the first embodiment is performed, and various spray shapes and injection directions can be formed, and atomization of fuel spray can be promoted.

Embodiment 3 FIG.
In the present embodiment, as shown in FIG. 3, when the valve is opened, the flow passage cross-sectional area of the seat portion 3c is S1, the flow passage cross-sectional area of the cavity 10 is immediately upstream of the injection hole 9b, and the injection flow is S2. When the channel cross-sectional area of the hole 9b is S3, it is configured to satisfy the relationship of S1>S2> S3.

  In the poppet valve structure, the valve body lift amount is likely to vary. In this case, the valve body lift amount is directly connected to the flow path cross-sectional area S1 of the seat portion 3c. If the flow rate characteristic and the spray characteristic depend on the pressure loss generated in the flow path cross-sectional area S1 of the seat portion 3c, when the valve lift amount varies, these characteristics also vary.

  However, as shown in FIG. 3, by configuring so as to satisfy the relationship of S1> S2> S3, the flow rate characteristic and the spray characteristic are generated in the channel cross-sectional area S2 of the cavity 10 and the channel cross-sectional area S3 of the injection hole 9b. Therefore, even if the valve lift amount varies, the flow passage cross-sectional area S2 and the flow passage cross-sectional area S3 are not affected, and the flow characteristics and the spray characteristics are less likely to vary.

  That is, the flow rate characteristic and the spray characteristic depend on the shape of the injection hole 9 b and the shape of the cavity 10. When a plurality of injection holes 9b are provided, the flow passage cross-sectional area S3 of the injection holes 9b is the sum of the plurality of injection holes 9b.

Embodiment 4 FIG.
6 is a cross-sectional view showing the tip of a fuel injection device according to Embodiment 4 of the present invention.
In the present embodiment, the plate is provided on the downstream side of the seat portion 3c so that the valve seat portion 2c has a tapered portion 2f whose diameter decreases toward the downstream side, and further, the injection hole 9b is not blocked. A valve body end face 2d opposite to the valve body 9 is provided on the valve body 2. That is, a convex portion is provided on the distal end surface of the valve body as in the second embodiment, but the side surface of the convex portion is inclined from the outside of the valve device 1 toward the center.

  By configuring as described above, in the fuel flow in the cavity 10 flowing toward the injection hole 9b, the flow Q of fuel flowing into the injection hole 9b in the radial direction from the axial center of the valve device 1 can be suppressed. The fuel flow R flowing from the outside of the cavity 10 toward the center is strengthened.

Therefore, atomization of the fuel spray can be further promoted.
In the above description, the side surface of the convex portion provided on the valve body is inclined. However, the side surface of the convex portion provided on the plate 9 may be inclined.

It is sectional drawing which shows the fuel-injection apparatus by Embodiment 1 of this invention. It is sectional drawing which shows the front-end | tip part of the fuel-injection apparatus by Embodiment 1 of this invention. It is sectional drawing which shows the front-end | tip part of the fuel-injection apparatus by Embodiment 1 of this invention. It is an expanded sectional view which shows a plate part. It is sectional drawing which shows the front-end | tip part of the fuel-injection apparatus by Embodiment 2 of this invention. It is sectional drawing which shows the front-end | tip part of the fuel-injection apparatus by Embodiment 4 of this invention.

Explanation of symbols

2 valve body, 2e convex part, 3 valve body, 3b valve seat, 9 plate, 9a convex part,
9b Injection hole, 10 cavity.

Claims (4)

In an outer valve-opening type fuel injection device that has a valve body provided with a valve seat and a valve body that is separated from and in contact with the valve seat and opens when the valve body moves downstream, the valve body together but provided a plate having an injection hole on a downstream side of the seat portion in contact with the valve seat, provided with a cavity communicating with the opening time of the injection hole between the end surface of the plate and the valve body, the flow of the seat portion Fuel injection characterized by satisfying the relationship of S1>S2> S3, where S1 is the channel cross-sectional area, S2 is the channel cross-sectional area of the cavity, and S3 is the channel cross-sectional area of the injection hole. apparatus. The fuel injection device according to claim 1, wherein the cavity is formed by providing a convex portion on the plate. The fuel injection device according to claim 1, wherein the cavity is formed by providing a convex portion on an end surface of the valve body. 4. The fuel injection valve according to claim 2, wherein a side surface of the convex portion is inclined.

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