JPH04234566A - Fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent deteriorated fuel atomization and icing from being caused by fuel or moisture adhering to the inwall surface in an air-fuel mixture passage, 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 having an air-fuel mixture passage 7 which is situated more downstream in the injecting direction than a fuel injecting port 14 and in which injection fuel and the assist air supplied from the air assist device are mixed together, is installed on the tip of an injection valve, and a heating heater 13 to heat the air-fuel mixture passage 7 is also installed around the nozzle 6.

Description

[Detailed description of the invention]

0001

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

0002

2. Description of the Related Art In order for an internal combustion engine to burn fuel efficiently while using less fuel, it is first necessary to supply fuel to a combustion chamber in a state in which 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 has been proposed that is equipped with an air assist device that vigorously jets the fuel toward the target and promotes atomization of the injected fuel, and also includes a cylindrical member (long nozzle) that guides the atomized air-fuel mixture to the vicinity of the intake valve. A fuel injection device in which a fuel injection valve is attached to a fuel injection valve has been proposed (Japanese Utility Model Publication No. 11364/1983).

0003

[Problems to be Solved by the Invention] However, in a fuel injection device in which a long nozzle as described above is attached to the tip of a fuel injection valve, since the distance from the injection port of the fuel injection valve to the injection port at the tip of the nozzle is long, engine At low temperatures, fuel may adhere to the nozzle tip or inner wall surface, resulting in poor fuel atomization, or the adhering fuel may evaporate all at once under operating conditions (for example, during deceleration), causing the engine's air-fuel ratio to deteriorate. Control accuracy may decrease. In addition to this fuel, moisture in the intake air may condense and adhere to the inner wall of the nozzle when the engine is stopped, and in cold regions, these water droplets may freeze and prevent the atomized fuel from being injected when the engine is started. A so-called icing phenomenon may occur.

An object of the present invention is to solve the above-mentioned problems when a long nozzle is attached to the tip of a fuel injection valve in a fuel injection device that promotes atomization of injected fuel using assist air.

[0005]

[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 nozzle having a mixture passage for mixing the injected fuel with the air ejected from the air assist hole is mounted on the downstream side in the injection direction from the fuel injection port of the fuel injection valve, and the mixture passage is heated. A fuel injection device is provided that is characterized by being provided with a heating means.

[0006]

[Operation] Fuel and water droplets adhering to the inner wall surface of the air-fuel mixture passage in the nozzle are heated and evaporated by the heating means, so icing is prevented and atomization of the fuel is promoted.

[0007]

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 the figure, 1 is a fuel injection valve, and 2 is an air assist device, which uses assist air from the device body (not shown) as fuel. An air delivery unit 3 distributes pressurized air around the injection valve 1, and an assist air supply unit 3 supplies pressurized air to the air delivery unit 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, through this mixture passage 7, the fuel injected from the nozzle 4 of the fuel injection valve 1 and the air (assist air) supplied from the air assist device are mixed uniformly, and the fuel is further atomized. Note that an O-ring 10 and an insulator 11 are installed between the air delivery 2 and the fuel injection valve 1 to seal the internal space 4 from the outside.

According to this embodiment, the mixture passage 7 is branched into two passages 7a and 7b near the tip of the long nozzle 6, and opens through mixture jet ports 12a and 12b. The branch passages 7a and 7b are arranged so that the atomized fuel flowing through the mixture passage 7 is divided equally, and in this embodiment is injected toward two intake valves (not shown). It is inclined at a predetermined angle with respect to the central axis A.

Furthermore, according to this embodiment, as a means for heating the above-mentioned mixture passage 7, a heater 13 is provided in the fuel injection valve 1 so as to cover the long nozzle 6 along its longitudinal direction.
will be provided. The heater 13 is made of, for example, a PTC (Positive Temperature Copper) having positive temperature characteristics that shows an increase in heater resistance when a certain temperature (Curie point) is reached.
By using a heater, it ensures instant heating when the engine is low, and also suppresses heat generation by making it difficult for current to flow when the temperature of the fuel injection device rises to a temperature that is less likely to attract fuel or water droplets. You can also do it. In addition, in FIG. 1, 14 and 15
indicates an O-ring, and 16 indicates a heater electrode.

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.

According to the illustrated embodiment, the connection point between the air assist hole where the injected fuel and the assist air join and the mixture passage is the mixture passage which extends along the central axis A starting from the injection port 4. 7, the fuel injected from the fuel injection valve 1 is
Immediately, they collide with the assist air flowing in from the air assist holes 9a and 9b and are atomized. The fuel atomized in this way flows in the mixture passage 7 toward the tip of the long nozzle 6, but in 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 air-fuel mixture stabilized in the mixing and flow direction as described above is divided almost equally and is injected from the air-fuel mixture jet ports 12a and 12b toward each intake valve. . The above-described operation is the normal fuel injection operation of the fuel injection device in this embodiment. In addition, when the engine temperature is low, such as during a cold start, this device automatically turns on the heater 1 before starting the engine.
3 is activated (energized) and generates heat. As a result, the mixture passage 7 (including the branch passages 7a and 7b) of the long nozzle 6 is heated, and the fuel and water droplets (including ice caused by icing) adhering to the inner wall surface are vaporized, and the subsequent Due to the fuel injection operation described above, the mixture is injected from the air-fuel mixture jet ports 12a and 12b.

The heater 13 is energized not only at the time of starting as described above but also after starting when the engine temperature is low to atomize the fuel adhering to the inner wall surface of the mixture passage 7. It may also be promoted. FIG. 2 shows a second embodiment of the present invention in which the structure of the heater is slightly different from that in FIG. In this embodiment, the same components as in the previous embodiment are given the same numbers.

According to this embodiment, a heater 17 having the function of the long nozzle described above is attached to the tip of the air delivery 2 attached to the fuel injection valve 1. That is, as is clear from the figure, a mixture passage 7 and branch passages 7a and 7b for mixing assist air and injected fuel are formed in the heater 17 itself, and this mixture passage 7 is connected to the tip of the fuel injection valve 1. The fuel passage 18a is connected to the fuel passage 18a formed in the adapter 18 attached to the adapter 18.

Furthermore, in this embodiment, a ring-shaped heat insulator 19 is installed between the adapter 18 and the heater 17. This is provided to prevent the heat of the heater 17 from being transferred to the fuel injection valve 1 main body, heating the valve main body, and generating bubbles in the fuel. The heat of the heater 17 is cut off by the heat insulating material 19 inserted between the two.

The operation of the fuel injection system of this embodiment is the same as that of the first embodiment, so a description thereof will be omitted. Although the embodiment of the present invention has been described above based on FIGS. 1 and 2, the form of the mixture passage is not limited to this embodiment, nor is the number of branch passages limited to two. . Naturally, the heat insulating material shown in the second embodiment may be attached to the fuel injection device of FIG. 1.

[0019]

As explained above, according to the present invention, the fuel, water droplets, or ice adhering to the inner wall surface of the air-fuel mixture passage in the nozzle are heated by the heating means and evaporated, so icing is prevented. Atomization of fuel is promoted.

[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 a main part of a second embodiment of the present invention.

[Explanation of symbols]

1...Fuel injection valve 6...Long nozzle 7...Mixture passage 13, 17...heater

Claims (1)

[Claims] 1. A fuel injection device for an internal combustion engine including an air assist device that atomizes fuel injected from a fuel injection valve with air, wherein the injected fuel and A fuel injection device comprising: a nozzle having a mixture passage for mixing with air ejected from an air assist hole; and heating means for heating the mixture passage.