JPH04234564A - Fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a fuel injection device capable of injecting air-fuel mixture stable in its component and its flow direction, in a fuel injection device equipped with an air assist device. CONSTITUTION:In a fuel injection device of an internal combustion engine equipped with an air assist device to transform fuel injected from a fuel injection valve 1 into particulates by means of assist air, a long nozzle 6 is formed on the tip of the injection valve, by which an air-fuel mixture passage 7 which is situated more downstream in the injecting direction than a fuel injecting port 4 and in which injection fuel and the assist air supplied from the air assist device are mixed together and air-fuel mixture blowout holes 12a and 12b which are formed shorter than the air-fuel mixture passage 7 and are connected to the end part of the air-fuel mixture passage and also branch and direct the air-fuel mixture in the plural desired directions are formed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] In order to improve the combustion and fuel efficiency of an internal combustion engine, the present invention provides an air assist device that atomizes fuel injected from a fuel injection valve using an injected air flow.
The present invention relates to a fuel injection device for an internal combustion engine.

0002

2. Description of the Related Art Generally, in order for an internal combustion engine to burn fuel efficiently while using less fuel, it is first necessary to supply fuel to the engine body in a state where it is most easily combustible. For internal combustion engines equipped with recent fuel injectors, air from outside is forced into the vicinity of the nozzle of the fuel injector in order to promote atomization of the fuel injected from the fuel injector. A fuel injection device equipped with an air assist device for promoting atomization of the injected fuel by vigorously ejecting the fuel toward the fuel has been proposed (Japanese Patent Application Laid-Open No. 1-271634, Japanese Utility Model Application No. 1-61461, etc.).

0003

[Problems to be Solved by the Invention] The conventional fuel injection device as described above has a structure in which an adapter having an air assist hole through which air from the air assist device is jetted is attached to the tip of the fuel injection valve. Further, this adapter is provided with an air-fuel mixture injection hole adjacent to the air assist hole for branching and injecting the air-fuel mixture (fuel+assist air) in a predetermined direction.

[0004] However, with an adapter having such a structure in which the air assist hole and the mixture injection hole are close to each other, the fuel and assist air are injected from the adapter as soon as they are mixed, so the flow remains unstable. The mixture flow is also branched into a plurality of mixture jet holes, and the fuel distribution is not necessarily uniform, resulting in a difference in the amount of fuel supplied between the intake ports, making combustion unstable. In addition, due to the instability of the air mixture flow, the components of the scattering direction of fuel particles become complicated, and the fuel spray that comes out of the air mixture nozzle quickly diffuses.
It is not possible to accurately inject fuel toward the targeted location.

The present invention is provided to solve the above-mentioned problems with fuel injection devices.

[0006]

[Means for Solving the Problems] According to the present invention, in order to solve the above-mentioned problems, there is provided a fuel injection device for an internal combustion engine that includes an air assist device that atomizes fuel injected from a fuel injection valve with air. , a mixture passage located downstream of the fuel injection port of the fuel injection valve in the injection direction and mixing the injected fuel with the air supplied from the air assist device; and a mixture passage formed shorter than the mixture passage. There is provided a fuel injection device characterized in that the tip of the fuel injection valve is equipped with a nozzle having a mixture injection hole connected to the end of the mixture passage and for branching and directing the mixture in a plurality of desired directions. .

[0007]

[Operation] Since a nozzle with a mixture passage longer than the mixture injection hole is provided at the tip of the fuel injection valve, the mixture of air and fuel flows through the mixture passage (time and distance). The flow direction of the fuel is stabilized, the mixing becomes uniform, and the amount of fuel to be distributed at the branch part can also be accurately defined.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described with reference to the drawings. FIG. 1 shows a fuel injection device according to a first embodiment of the present invention, in which 1 is a fuel injection valve and 2 is an air assist device, which injects assist air from the device body (not shown) into fuel. An air delivery unit 3 distributes air around the valve 1, and 3 is an assist air supply unit that supplies pressurized air from an air pump (not shown) to the air delivery 2.

The fuel injection valve 1 has a fuel injection port (hereinafter referred to as injection port) 4 on its central axis A, and a needle valve 5 is provided inside the main body of the fuel injection valve 1 in the direction of the central axis A. is attached so that it can move back and forth. According to the present embodiment in the fuel injection device configured as described above, the fuel injection valve 1
A long nozzle 6 is attached to the tip of the tube along the central axis A.

A mixture passage 7 is formed inside the long nozzle 6 so as to extend downstream in the fuel injection direction from the injection port 4 along the central axis A, and the mixture passage 7 and the air delivery passage 7 are connected to each other. Air assist holes 9a and 9b are formed which communicate with the internal space 8 of No. 2. That is, this air-fuel mixture passage 7 allows the fuel injected from the nozzle 4 of the fuel injection valve 1 to
Air supplied from the air assist device (assist air)
This provides a space for mixing the fuel and atomizing the fuel. still,
An internal space 4 is provided between the air delivery 2 and the fuel injection valve 1.
An O-ring 10 and an insulator 11 are attached for sealing from the outside.

The mixture passage 7 extends to the vicinity of the tip of the long nozzle 6. At the tip of the long nozzle 6, there are mixture jet ports 12a, 12 which are shorter than the length of the mixture passage 7.
b is formed. These air-fuel mixture jet ports 12a and 12b are connected to the terminal end of the air-fuel mixture passage 7, and the air-fuel mixture flowing through the passage 7 is branched at the terminal end.
so that it is injected toward two intake valves (not shown).
It is inclined at a predetermined angle with respect to the central axis A.

The operation of the fuel injection system of this embodiment will be explained below with reference to the drawings. By operating the needle valve 5, the fuel in the fuel injection valve 1 is injected from the injection port 4 into the mixture passage 7, but on the other hand, the assist air (pressurized air) from the air assist device is The air is supplied into the air delivery 2 through the assist air supply section 3, and is discharged into the mixture passage 7 through the air assist holes 9a, 9b. The connection point between the air assist hole, which is the confluence of the injected fuel and the assist air, and the mixture passage is a mixture line extending along the central axis A, with the starting point at the injection port 4 and the connection point with the mixture injection port 12a, 12b as the ending point. Since it is close to the injection port 4 in the air passage 7, the fuel injected from the fuel injection valve 1 immediately collides with the assist air injected from the air assist holes 9a, 9b and is atomized. The fuel atomized in this way flows in the mixture passage 7 toward the tip of the long nozzle 6, but during this flow process, the atomized fuel is sufficiently mixed with the assist air, and the component in the flow direction is also More uniform.

The mixture stabilized in the mixing and flow direction as described above is divided equally at the connection portion of the mixture jet ports 12a and 12b, which are the ends of the mixture passage 7, and 12a and 12b toward each intake valve, and even after division, the fuel distribution amount of each air-fuel mixture is stabilized. In forming each flow path in the long nozzle 6 described above, the inner diameters of the air assist holes 9a, 9b, the mixture passage 7, and the mixture jet ports 12a, 12b are set to D9, D7,
and D12, 2・(D12)2 >(D7)
If the relationship of 2 > 2·(D9) 2 is established, the flow velocity of the assist air passing through the air assist holes 9a and 9b will be the highest, and fuel atomization will be improved.

FIG. 2 shows an example in which the above-described fuel injection device is installed in an internal combustion engine having a two-intake port configuration. As is clear from this figure, the fuel injection device according to this embodiment includes a long nozzle 6 at the tip of the fuel injection valve 1, so that the intake valve 15 as shown in the figure Even in the case where the fuel injection valve is installed far away, by installing a long nozzle, the fuel injection port of the fuel injection device itself, that is, the mixture injection port 12a, can be brought as close as possible to the intake valve 15, and as a result, the injected fuel port Wall adhesion can be kept low compared to fuel injection devices without long nozzles. Although not shown in the drawings, in order to further enhance the effect of suppressing fuel adhesion, a long nozzle may be inserted into the port partition wall to further shorten the distance from the intake valve. In addition, since the distance from the connection part of the mixture jet ports 12a and 12b to the opening of the mixture jet port is short compared to the mixture passage length, the mixture flow branched at the connection part is branched in the flow direction. With the disturbance still occurring,
It is injected from the jet ports 12a and 12b. Therefore, the air-fuel mixture is dispersed over a wide range and heads toward the intake valve, so that the entire air-fuel mixture is thoroughly sucked in without being reflected by collision at the intake valve 15.

FIG. 3 shows a fuel injection device as a second embodiment, which is equipped with an air-fuel mixture injection port that is slightly different from the air-fuel mixture injection port configuration of the device shown in FIG. This embodiment differs from the previous embodiment in that air-fuel mixture jets 12a and 12 are provided on the tip surface of the long nozzle 6.
b opens on the side near the tip of the long nozzle 6. However, due to the side placement of the jet nozzle, the degree of collision between the airflow in the intake port shown by the arrow in the figure and the mixture from the mixture jet nozzle is increased, which again promotes atomization of the injected fuel. .

[0016]

As explained above, according to the present invention, since a nozzle having a mixture passage longer than the mixture injection hole is provided at the tip of the fuel injection valve, the mixture of air and fuel can be drawn into the mixture passage. In the process of flowing the air-fuel mixture, the flow direction of the air-fuel mixture is stabilized and the mixture is made uniform, and then this air-fuel mixture is split, so even in the split air-fuel mixture, the injection direction is stabilized, and the amount of fuel distributed can be precisely controlled. can be managed,
Combustion is therefore improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a first embodiment of the present invention.

FIG. 2 is a sectional view of an internal combustion engine body equipped with a fuel injection device according to the present invention.

FIG. 3 is a sectional view of a main part of a second embodiment of the present invention.

[Explanation of symbols] 1...Fuel injection valve 4...Fuel injection port 6...Long nozzle 7...Mixture passage 12a, 12b...Mixture outlet

Claims (1)

[Claims] 1. A fuel injection device for an internal combustion engine comprising an air assist device that atomizes fuel injected from a fuel injection valve with air, wherein the fuel injection device is located downstream of the fuel injection port of the fuel injection valve in the injection direction, a mixture passage that mixes the injected fuel with the air supplied from the air assist device, and a mixture passage that is formed shorter than the mixture passage and connected to the end of the mixture passage, and that branches the mixture into a plurality of desired directions. A fuel injection device comprising: a nozzle having a mixture injection hole at a tip of the fuel injection valve.