JP2531526Y2 - Fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fuel injection device for an internal combustion engine.

[Conventional technology]

A nozzle port that is electromagnetically controlled by a needle to inject fuel using compressed air is provided, and a compressed air passage extending from the nozzle port along the needle is formed around the needle to compress this compressed air passage. Providing a nozzle chamber connected to an air source and opening into the compressed air passage, arranging the injection port of the fuel injection valve at the back of the nozzle chamber, and opening the needle after injecting fuel from the injection port toward the needle There is known a fuel injection valve in which the injected fuel is injected from a nozzle port together with compressed air by the use of a so-called air blast valve (see Japanese Patent Publication No. 63-500323). With this air blast valve, good atomization of the injected fuel can be ensured by using low-pressure compressed air.

[Problems to be solved by the invention]

However, if the injection port of the fuel injection valve is arranged at the back of the nozzle chamber that opens into the compressed air passage as in the above-described air blast valve, the compressed air hardly flows through the nozzle chamber when the needle is opened, and thus, There is a problem that the injected fuel is accumulated because the fuel attached to the inner wall surface of the nozzle chamber cannot be carried away by the compressed air.

[Means for solving the problem]

According to the present invention, in order to solve the above-described problems, a nozzle port controlled to be opened and closed by a needle and a compressed air passage communicating with the nozzle port are provided, and fuel supplied to the compressed air passage is supplied to the compressed air passage. In a fuel injection device in which a needle is opened by a supplied compressed air when a needle is opened, an air introduction hole for supplying compressed air into a compressed air passage is provided in the compressed air passage. Compressed air in the compressed air passage which is opened obliquely in the direction of the compressed air flow inside and substantially tangentially to the inner peripheral surface of the compressed air passage and stays stationary when the needle is closed. When the needle is opened, fuel is supplied to the inside of the nozzle, and the fuel adhering to the inner peripheral surface of the compressed air passage is discharged by the compressed air flow that flows out of the air introduction hole and moves forward while turning in the compressed air passage. So that it carries away towards the mouth.

[Action]

Since the compressed air supplied from the compressed air supply port into the compressed air passage flows in a swirling flow along the inner peripheral surface of the compressed air passage, the fuel attached to the inner wall surface of the compressed air passage is carried away by the compressed air. And is ejected from the nozzle port together with the compressed air.

〔Example〕

Referring to FIGS. 4 and 5, 1 is a cylinder block, 2 is a piston, 3 is a cylinder head, 4 is a combustion chamber, 5 is a pair of air supply valves, 6 is an air supply port, and 7 is a pair of exhaust valves. , 8 denotes an exhaust port, and 9 denotes a spark plug. A mask wall 10 is formed on the inner wall surface of the cylinder head 3 so as to close the opening between the peripheral portion of the supply valve 5 on the exhaust valve 7 side and the valve seat during the full opening period of the supply valve 5. Therefore, when the air supply valve 5 is opened, fresh air flows into the combustion chamber 4 from the side opposite to the exhaust valve 7 as shown by an arrow A. An air blast valve 20 is arranged on the inner wall surface of the cylinder head 3 located between the pair of air supply valves 5.

FIG. 3 shows a partial cross-sectional side view of the air blast valve 20.
Referring to FIG. 3, the housing 21 of the air blast valve 20
A straight needle insertion hole 22 is formed inside,
A needle 23 having a smaller diameter than the needle insertion hole 22 is inserted into the needle insertion hole 22. A nozzle port 24 is formed at one end of the needle insertion hole 22, and the nozzle port 24 is
The opening / closing is controlled by a valve section 25 formed at the tip of the.
In the embodiment shown in FIG. 3, this nozzle port 24 is arranged in the combustion chamber 4. The needle 23 has a spring retainer.
26 is fixed, and this spring retainer 26 and housing
A compression spring 27 is inserted between the two. The nozzle port 24 is normally closed by the valve portion 25 of the needle 23 by the spring force of the compression spring 27. A movable core 28 is always in contact with the end of the needle 23 opposite to the valve portion 25 by the spring force of a compression spring 29, and a solenoid 30 for sucking the movable core 28 and a stator are provided in the housing 21. 31 is arranged. When the solenoid 30 is energized, the movable core 28 moves toward the stator 31, and as a result, the needle 23 moves in the direction of the nozzle port 24 against the spring force of the compression spring 27, so that the nozzle port 24 is opened. Can be

Referring to FIGS. 1 and 3, a cylindrical nozzle chamber 32 is formed in the housing 21. The nozzle chamber 32 has a large diameter portion 32a and a small diameter portion 32b concentric with the large diameter portion 32a. A peripheral portion 32c of the large diameter portion 32a is communicated with a compressed air source 34 via a compressed air supply passage 33, and a top portion 32d of the small diameter portion 32b is formed.
Is communicated with the inside of the needle insertion hole 22 through a compressed air outflow passage 35 concentric with the small diameter portion 32b. A socket 40 is fitted in the nozzle chamber 32. The socket 40 is a large-diameter cylindrical part 40
a, and a small-diameter cylindrical portion 40b concentric with the large-diameter cylindrical portion 40a. The large-diameter cylindrical portion 40a is formed with a cylindrical concave portion 40c in which the nozzle portion 44 of the fuel injection valve 36 is fitted, and the small-diameter cylindrical portion 40b has a cylindrical injection passage 40d having the same diameter as the compressed air outflow passage 35. It is formed penetrating from the concave portion 40c. Since the axial length of the small-diameter cylindrical portion 40b is longer than the axial length of the small-diameter portion 32b of the nozzle chamber 32, an annular space 42 is formed between the large-diameter portion 32a and the small-diameter cylindrical portion 40b. 2 on the peripheral wall of the small-diameter cylindrical portion 40b
One air introduction hole 40e is formed. The air introduction hole 40e extends obliquely with respect to the fuel passage 40d toward the compressed air outflow passage 35, and communicates the annular space 42 with the fuel passage 40d.

FIG. 2 shows the small-diameter cylindrical portion 40b taken along the line II of FIG. Referring to FIG. 2, the air introduction hole 40e is
It extends tangentially to the inner peripheral wall surface of the injection passage 40d. The two air introduction holes 40e extend in opposite directions from positions on the circumference where the central angles are 180 degrees with each other. Therefore, when air is introduced into the injection passage 40d from the two air introduction holes 40e,
The air is swirled clockwise B along the inner peripheral surface of the injection passage 40d.
Occurs.

The nozzle portion 44 of the fuel injection valve 36 is fitted in the cylindrical concave portion 40c of the large-diameter cylindrical portion 40a.

As shown in FIG. 1, the compressed air outflow passage 35 extends straight. The injection port 37 of the nozzle portion 44 is disposed on the axis of the injection passage 40d and the compressed air outflow passage 35, and fuel having a small divergence angle is injected from the injection port 37 along the axis of the injection passage 40d and the compressed air outflow passage 35. . Air inlet 40
The position of the opening 40f to the fuel passage 40d in the axial direction of the fuel passage 40d is such that the injected fuel from the injection hole 37 hardly collides with the opening 40f. Therefore, fuel hardly adheres to the inner wall surface of the injection passage 40d between the injection port 37 and the opening 40f. The compressed air outflow passage 35 faces the needle insertion hole 22 toward the nozzle port 24.
To the needle insertion hole 22
It is connected to the needle insertion hole 22 at an angle of 45 degrees from the angle.

The annular space 42, the air introduction hole 40e, and the injection passage 40d, the compressed air outflow passage 35, and the needle insertion hole 22 forming the compressed air passage are connected to the compressed air source 34 via the compressed air supply passage 33.
Is in communication with Accordingly, the inside of the annular space 42, the air introduction hole 40e, the injection passage 40d, the compressed air outflow passage 35, and the needle insertion hole 22 are filled with compressed air. The injection passage 40d and the compressed air outflow passage 3
Fuel is injected along the 5 axis. FIG. 1 and FIG.
As shown in the figure, the compressed air outflow passage 35 is obliquely connected to the needle insertion hole 22, so that most of the injected fuel reaches the needle insertion hole 22 around the needle 23 near the valve portion 25. At this time, some fuel adheres to the inner wall surface of the injection passage 40d downstream of the opening 40f and the inner wall surface of the compressed air outflow passage 35. Next, when the solenoid 30 is energized, the needle 23
Opens the nozzle port 24. At this time, as soon as the needle 23 opens the nozzle port 24, the fuel and the compressed air are both supplied from the nozzle port 24 to the combustion chamber 4 because the injected fuel is collected near the valve portion 25.
Spouts in. When the needle 23 opens the nozzle port 24, the compressed air flows into the annular space 42 from the compressed air supply passage 33, and then flows into the injection passage 40d and the compressed air outflow passage 35 from the air introduction hole 40e. The air introduced from the air introduction hole 40e is supplied to the injection passage 40d and the compressed air outflow passage 35.
A swirling flow along the inner peripheral wall faces the nozzle port 24. For this reason, the fuel adhering on the inner peripheral wall surface of the injection passage 40d and the compressed air outflow passage 35 is carried away by the compressed air flow,
It is ejected from the nozzle port 24. Therefore, as soon as the needle 23 is opened, all of the injected fuel is ejected from the nozzle port 24, and when the ejection of all these injected fuels is completed, only the compressed air is ejected from the nozzle port 24. Next, the solenoid 30 is deenergized and the needle 23 is moved to the nozzle port 24.
Is opened. Therefore, just before the needle 23 is closed, only air is ejected from the nozzle port 24.
Just before the needle 23 closes, the fuel still
When the fuel is jetted from the nozzle 24, when the needle 23 is closed, the opening area of the nozzle port 24 becomes small and the flow rate of the compressed air decreases, so that the fuel is not atomized and the liquid fuel adheres around the nozzle port 24. As described above, when the liquid fuel adheres around the nozzle port 24, carbon is deposited around the nozzle port 24, which hinders the fuel injection action. However, in this embodiment, only compressed air is ejected immediately before the needle 23 closes, so that no liquid fuel adheres around the nozzle port 24, and therefore there is no danger of carbon being deposited around the nozzle port 24. .

FIG. 5 shows a case in which the air blast valve 20 is applied to a two-stroke engine. The fuel injection from the air blast valve 20 is started slightly before the air supply valve 5 closes. During low engine load operation, the injected fuel collects around the spark plug 9 because the flow rate of the fresh air A flowing into the combustion chamber 4 is low, and thus good ignition is performed. On the other hand, at the time of engine high load operation, a strong loop scavenging is performed because the flow velocity of the fresh air A is high, and the injected fuel is carried along the inner wall surface of the combustion chamber 4 by the fresh air flow A flowing in a loop shape. Inside, a homogeneous mixture is formed. As a result, high engine output can be secured.

In this embodiment, the injection port 37 of the fuel injection valve 36 is arranged at the upstream end of the injection path 40d which is a part of the compressed air path, and the air introduction hole 40e is formed in the injection path 40d between the nozzle port 24 and the injection port 37. Although the opening 40f is formed, the injection port of the combustion injection valve may be provided in the compressed air passage between the nozzle port 24 and the opening of the air introduction hole (downstream from the opening of the air introduction hole). .

Further, a fuel injection device using the air injection valve for controlling the air injection by disposing the nozzle port 24 in the engine intake passage, wherein the air is injected from the air injection valve into the compressed air passage. In a fuel injection device that injects fuel from the fuel injection valve into the compressed air passage only to inject fuel and air from the nozzle opening into the intake passage, an on-off valve that opens and closes the nozzle opening 24 is unnecessary. .

[Effect of the invention]

The air introduction hole for supplying the compressed air into the compressed air passage is opened obliquely in the compressed air passage in the direction of the compressed bending flow in the compressed air passage. The compressed air flows into the compressed air passage from the introduction hole with a velocity component in the direction of the compressed air flow in the compressed air passage. Thus, the compressed air flows at a high speed in the compressed air passage toward the nozzle port. Moreover, at this time, a swirling flow is given to the compressed air which has flowed into the compressed air passage from the air introduction hole, so that the compressed air carries the fuel adhering on the entire inner peripheral surface of the compressed air passage at a high speed while removing the fuel attached to the nozzle port. Flows towards As a result, all the fuel injected into the compressed air passage is ejected together with the compressed air, so that the injected fuel amount does not vary, and stable combustion can be ensured.

[Brief description of the drawings]

1 is an enlarged sectional view of a main part of an air blast valve, FIG. 2 is an enlarged sectional view of a socket taken along line II of FIG. 1, FIG. 3 is a partial sectional side view of the air blast valve, FIG. 4 is a bottom view of the inner wall surface of the cylinder head, and FIG. 5 is a side sectional view of the two-stroke engine. 20 …… Air blast valve, 22 …… Needle insertion hole, 23 ……
Needle, 24 ... Nozzle port, 33 ... Compressed air supply path, 34
… Compressed air source, 35… Compressed air outflow passage, 36… Fuel injector, 40… Socket, 40e… Air introduction hole, 42…
Annular space.

Continuing on the front page (72) The creator, Manabu Tateno 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. References JP-A-57-146048 (JP, A) JP-A-57-179367 (JP, A) JP-A-58-195058 (JP, A) JP-A-60-501963 (JP, A) JP-A-63 −500323 (JP, A)

Claims (1)

(57) [Scope of request for utility model registration] A nozzle opening controlled to be opened and closed by a needle; and a compressed air passage communicating with the nozzle opening. Fuel supplied to the compressed air passage is supplied by compressed air supplied to the compressed air passage. In a fuel injection device in which a needle is opened from the nozzle port when the valve is opened, an air introduction hole for supplying compressed air into the compressed air passage is provided in the compressed air passage with a compressed air in the compressed air passage. Opened obliquely in the direction of air flow and substantially tangentially to the inner peripheral surface of the compressed air passage, and inside the compressed air in the compressed air passage that is stationary when the needle valve is closed. When the needle is opened, fuel flows out of the air introduction hole, and the fuel adhering to the inner peripheral surface of the compressed air passage is swept through the compressed air passage while moving forward in the compressed air passage. Only the fuel injection system of an internal combustion engine so as to carry away.