JPH04259663A - Fuel injection device of internal combustion engine - Google Patents

Abstract

PURPOSE:To make fuel particles finer by achieving uniformly mixed condition of the compressed air and atomized fuel injected from a nozzle even in case the fuel injection is made with a large quantity. CONSTITUTION:Compressed air is led from an air source 43 to a nozzle 23 being routed via a passage 44, solenoid chamber 39, communication hole 45, passage 50, nozzle chamber 46, passage 47, and a widened chamber 81. A fuel injection valve 51 spouts the pressurized fuel from a jet 52, and the atomized fuel assumes thin strips, passes through the nozzle chamber 46 and passage 47, flows into the widened chamber 81 tangentially, and swirls as creeping on the wall of the chamber 81. Therefore, the gaseous phase portion consisting of compressed air, etc., remains in the central part, and there is no risk of the area around the nozzle 23 being filled with the fuel solely.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an internal combustion engine, and more particularly to a fuel injection device for injecting fuel into a cylinder or an intake passage of an engine using compressed air.

0002

[Prior Art] In order to inject fuel using compressed air, a nozzle opening is controlled to open and close by an electromagnetically driven needle, and a compressed air passage extending from the nozzle opening along the needle is provided around the needle. A needle guide is integrally formed on the needle near the nozzle opening to be slidably guided by the inner wall surface of the compressed air passage, and the compressed air passage is connected to a compressed air source. A nozzle chamber is provided in the passage, and the nozzle of the fuel injection valve is placed in the deep part of the nozzle chamber. Fuel is injected from the nozzle toward the needle, and then the needle is opened, so that the injected fuel is delivered to the nozzle along with compressed air. A so-called air blast valve, which is a fuel injection valve that injects fuel from the air, is well known. (Refer to Japanese Patent Publication No. 1988-501963). According to this air blast valve, good atomization of the injected fuel can be ensured using low-pressure compressed air.

0003

[Problems to be Solved by the Invention] With this air blast valve, when there is a large amount of metered fuel from the fuel injection valve, the fuel reaches the nozzle port before the nozzle port opens, and the nozzle port is filled with fuel. There was a problem in that the fuel was injected as coarse particles without the fuel and air mixing at the beginning of the injection. In view of this problem, the present invention aims to ensure good atomization even when a large amount of metered fuel is used.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a nozzle opening that opens at the end of a compressed air passage formed in a body, and a tip that opens and closes the nozzle opening for controlling opening and closing of the nozzle opening. a needle having a valve portion and slidably supported within the body; a chamber coaxially formed around the needle in the vicinity of the nozzle opening and forming a part of the compressed air passage; and a fuel injection valve attached to a part of the body for injecting fuel into the compressed air in the air and mixing the air and fuel, and when the nozzle opening is opened by the valve portion of the needle. The fuel mixed with compressed air is configured to be ejected from the nozzle port, and the fuel injection direction of the fuel injection valve is set to be tangential to the chamber, thereby An internal combustion engine characterized in that a swirling fuel spray along the wall surface of the chamber and a gas phase portion such as compressed air containing substantially no liquid fuel are generated around the needle at the center. Provides fuel injection equipment.

[0005]

[Operation] Since the fuel injection device of the present invention has the above-described configuration, the fuel injected from the fuel injection valve into the chamber in the tangential direction becomes a vortex-like spray along the wall surface of the chamber, and swirls within the chamber. During this process, it mixes with compressed air, and the fuel droplets become fine and some of them vaporize.

[0006] Until the fuel spray is vaporized, it is a granular liquid and has a higher specific gravity than compressed air containing partially vaporized fuel, so it flows unevenly along the wall of the chamber due to the centrifugal force caused by swirling. Around the needle in the center of the chamber, a gas phase portion consisting of compressed air and partially vaporized fuel is formed. Therefore, even during high-load operation with a large amount of fuel injection, the upstream side of the nozzle port is filled with liquid fuel before it opens, and when the nozzle port opens, only liquid fuel is ejected first and fuel is then Problems such as compressed air containing a small amount of steam being ejected do not occur, and when the nozzle opening opens, a mixture with a uniform concentration and well-atomized fuel particles is injected from the nozzle opening. , the combustion condition is stabilized.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a side view of an air blast valve 20 which is an embodiment of the present invention. In the body 21 of the air blast valve 20, a needle insertion hole 22 extending straight along the axis A and a chamber 81 having a larger diameter than the needle insertion hole 22 are formed. is formed, and the other end communicates with a spring chamber 24 formed in the body 21 coaxially with the axis A of the needle insertion hole 22. Inside the needle insertion hole 22, there is a portion 36 having a smaller diameter than the needle insertion hole 22, as shown in FIG. 3(b).
A needle 25 having a vertical spacer 37 as shown in FIG. The air blast valve 20 of this embodiment is arranged so that the nozzle port 23 faces into a combustion chamber of an internal combustion engine (not shown).

A drive unit housing 27 is attached to the upper end of the body 21 in which the spring chamber 24 is formed, and a stator 28 is fixed within the lower end of the housing 27, facing the spring chamber 24. A spring retainer 29 is fixed to the needle 25 located near the upper end of the spring chamber 24 , and a compression spring 30 is inserted into the spring chamber 24 between the spring retainer 29 and the body 21 . The spring force of the compression spring 30 urges the needle 25 upward, and the nozzle port 23 is normally closed by the valve portion 26 of the needle 25.

The needle 25 passes through the stator 28,
The rear end 31 of the needle 25 projects upwardly from the opening 60 of the stator 28 . A movable core 32 is constantly brought into contact with this rear end portion 31 by the spring force of a compression spring 33. The movable core 32 is disposed in a movable core insertion hole 40 formed in the central cylindrical portion of the stator member 55 integrated with the housing 27 in the direction of the axis A, so as to be slidable in the direction of the axis A. ing. Note that 59 is a screw plug that supports the upper end of the compression spring 33. The biasing force in the valve opening direction by the compression spring 33 is about half the biasing force in the valve closing direction by the compression spring 30, and the nozzle port 23 is always closed due to the difference in the biasing forces of these compression springs 30 and 33. becomes.

A solenoid chamber 39 is formed by the stator 28 and the housing 27, and a solenoid 34 is disposed around the stator 28 within this solenoid chamber 39. When this solenoid 34 is energized, the movable core 32 is slid in the movable core insertion hole 40 toward the stator 28 , and at the same time, the needle 25 is moved in the direction of the nozzle opening 23 against the spring force of the compression spring 30 . Since the nozzle port 23 is slidably displaced, the nozzle port 23 opens.

A compressed air introduction passage 41 is formed above the housing 27 on an extension of the axis A of the needle insertion hole 22. A strainer 42 is provided in the middle of the compressed air introduction passage 41, and the compressed air introduction passage 41 is compressed at an upstream side (not shown) by a compressed air passage common to the air introduction passages of the air blast valves of other cylinders. It is connected to a compressed air source 43 such as a machine. Compressed air introduction path 4 on the downstream side
1 communicates with the solenoid chamber 39 formed in the housing 27 through a passage 44 provided in the upper connector member and inclined with the A axis, without passing near the movable core 32.

The flange portion of the stator 28 is shown in FIG. 3 (a).
), there are several communication holes 45 in one part of the entire circumference.
is formed, and this communication hole 45 communicates the solenoid chamber 39 and the spring chamber 24. Therefore, the compressed air introduction path 41 includes the inclined air passage 44, the solenoid chamber 39, and the communication hole 4.
5 to the spring chamber 24, and these air passages 44
, the solenoid chamber 39, the communication hole 45, and the spring chamber 24 are filled with compressed air. The spring chamber 24 and the nozzle chamber 46 for the fuel injection valve 51 are communicated via an air passage 50 .

A cross-sectional shape taken along line II--II in FIG. 1 is shown in FIG. A fuel injection valve 5 is provided in the nozzle chamber 46.
The nozzle 52 is arranged so that one nozzle 52 is open. The fuel injection valve 51 and its nozzle 52 are arranged on the axis B, and fuel is injected from the nozzle 52 along the axis B at a small spread angle as seen in FIG. As is clear from these figures, on the axis B of the fuel injection valve 51 and its nozzle 52, an air outflow passage 47 is connected to the nozzle chamber 44 and the chamber 81.
However, the air outflow passage 47 is offset from the axis A of the chamber 81 and is connected to the chamber 81 in a tangential manner.

Next, the operation of the embodiment device will be explained. As mentioned above, the needle insertion hole 22, the chamber 81, the compressed air outlet passage 47, the nozzle chamber 46, and the compressed air passage 50 are communicated with the compressed air source 43 via the spring chamber 24 and the compressed air introduction passage 41. These passages are then filled with compressed air. In this compressed air, the fuel injection valve 5
Fuel is injected from one nozzle 52 along axis B.

Therefore, the atomized fuel F injected from the fuel injection valve 51 becomes a thin streak-like flow and is supplied to the chamber 81 from the tangential direction through the compressed air outflow passage 47.
Due to centrifugal force, it flows in a spiral along the wall surface of the chamber 81 as shown in FIG. Therefore, the needle at the center of the chamber 81 is not blocked by fuel, and the needle at the center of the chamber 81 is not blocked by fuel.
An air passage is always ensured in the center of 1.

Next, when the solenoid 34 is energized, the movable core 32 slides toward the stator 28, and the movable core 32 moves the needle 25 in the direction of the nozzle port 23 against the biasing force of the compression spring 30. As a result, the nozzle port 23 opens. Then, the atomized fuel spray mixed well with air is ejected from the nozzle port 23 into the combustion chamber 54 of the internal combustion engine.

[0017]

[Effects of the Invention] By carrying out the present invention, even under high load conditions with a large amount of fuel injection, the uniformity of the injected air-fuel mixture increases and the refinement of fuel particles progresses, thereby improving the combustion state in the internal combustion engine. becomes better, combustion efficiency, output,
Performance is improved in all aspects, including acceleration, the amount of harmful substances in the exhaust, and noise.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG. 1;

[Fig. 3] (a) is a cross-sectional view taken along III-III in Fig. 1;
b) is a sectional view taken along IV-IV in FIG.

[Explanation of symbols]

20...Air blast valve 23...Nozzle mouth 25...Needle 43...Compressed air source 51...Fuel injection valve 81...Chamber 32...Movable core

Claims (1)

[Claims] 1. A nozzle opening that opens at the end of a compressed air passage formed in a body, and a valve portion at the tip for controlling opening and closing of the nozzle opening, and is supported so as to be slidable within the body. a chamber formed coaxially around the needle in the vicinity of the nozzle opening and forming a part of the compressed air passage, and mixing air and fuel by injecting fuel into the compressed air in the chamber. a fuel injection valve attached to a part of the body in order to In addition, the fuel injection direction of the fuel injection valve is set to be tangential to the chamber, so that a swirling fuel spray along the wall surface and a central spray are formed in the chamber. A fuel injection device for an internal combustion engine, characterized in that a gas phase portion of compressed air or the like that does not substantially contain liquid fuel is generated around the needle.