JP2668130B2 - Fuel injection device for internal combustion engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel supply 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 A fuel injection valve, which is capable of injecting injected fuel together with compressed air from a nozzle port, is known from a so-called air blast valve (see Japanese Patent Publication No. Sho 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, a nozzle port is formed at one end of a needle insertion hole, a needle smaller in diameter than the needle insertion hole is inserted into the needle insertion hole, and the needle is electromagnetically controlled. By controlling the opening and closing of the nozzle port by the valve portion formed at the tip of the needle, the compressed air passage connected to the compressed air source is connected to the needle insertion hole at an angle to the needle insertion hole, and the side opposite to the nozzle port is connected. At the needle adjacent to the communicating portion between the compressed air passage and the needle insertion hole, an enlarged portion that closes the cross section of the needle insertion hole is formed, and the fuel injection valve is arranged in the compressed air passage.

(Operation)

The enlarging part of the needle prevents the fuel from entering and adhering to the inner part of the needle insertion hole, and the fuel adhering to the inner wall surface of the needle inserting hole is scraped off by the enlarging part, so all the injected fuel is ejected from the nozzle port. Can be

〔Example〕

2 and 3, 1 is a cylinder block, 2 is a piston, 3 is a cylinder head, 4 is a combustion chamber, 5 is a pair of supply valves, 6 is a 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 to close the opening between the peripheral portion of the air supply valve 5 on the exhaust valve 7 side and the valve seat over the fully open engine of the air 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. 1 shows a partial cross-sectional side view of the air blast valve 20 of the first embodiment. Referring to FIG. 1, the air blast valve 20
Needle insertion hole that extends straight inside the housing 21
A needle 22 having a smaller diameter than the needle insertion hole 22 is inserted into the needle insertion hole 22. At one end of the needle insertion hole 22, a nozzle port 24 is formed.
The opening and closing of the needle 24 is controlled by a valve part 25 formed at the tip of the needle 23. In the first embodiment shown in FIG. 1, this nozzle port 24 is arranged in the combustion chamber 4. A spring retainer 26 is fixed to the needle 23, and a compression spring 27 is inserted between the spring retainer 26 and the housing 21. 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. Movable core when solenoid 30 is energized
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.

On the other hand, a cylindrical nozzle chamber 32 is formed in the housing 21. One end 32a of the nozzle chamber 32 is connected to the compressed air inflow passage 3
3 through a nozzle chamber 32.
The other end 32b is communicated with the inside of the needle insertion hole 22 through the compressed air outflow passage 35. In the nozzle chamber 32, an injection port 37 of a fuel injection valve 36 is arranged.
Located between one end 32a and the other end 32b. As shown in FIG. 1, the compressed air outflow passage 35 extends straight. The injection port 37 is arranged on the axis of the compressed air outflow passage 35,
Fuel having a small divergence angle is injected from the injection port 37 along the axis of the compressed air outflow passage 35. The compressed air outflow passage 35 extends obliquely with respect to the needle insertion hole 22 toward the nozzle port 24, and is obliquely connected to the needle insertion hole 22 at an angle of 20 to 45 degrees with respect to the needle insertion hole 22. .

The needle insertion hole 22, the nozzle chamber 32 and the compressed air outflow passage 35 communicate with a compressed air source 34 via a compressed air inflow passage 33. Therefore, these needle insertion hole 22, nozzle chamber 32
The inside of the compressed air outflow passage 35 is filled with compressed air. Fuel is injected into the compressed air from the injection port 37 along the axis of the compressed air outflow passage 35. As shown in FIG. 1, since the compressed air outflow passage 35 is obliquely connected to the needle insertion hole 22, most of the injected fuel reaches the needle insertion hole 22 around the needle 23 near the valve portion 25. At this time, part of the fuel is supplied to the inner wall surface of the compressed air outflow passage 35 and the nozzle chamber 32.
Adheres to the inner wall surface of Next, when the solenoid 30 is energized, the needle 23 opens the nozzle port 24. At this time the valve section
As soon as the needle 23 opens the nozzle port 24, the fuel and the compressed air are both
The fuel is jetted from 24 into the combustion chamber 4. When the needle 23 opens the nozzle port 24, the compressed air flows into the nozzle chamber 32 from the compressed air inflow passage 33, and then flows to the nozzle port 24 via the compressed air outflow passage 35, so that the compressed air outflow passage 35 The fuel adhering to the inner wall surface and the inner wall surface of the nozzle chamber 32 is carried away by the compressed air flow and 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 supplied to the nozzle port 24.
It is blown out from. Next, the solenoid 30 is deenergized, and the needle 23 closes the nozzle port 24. Therefore the needle
Immediately before the valve 23 is closed, only air is ejected from the nozzle port 24. If the fuel is still ejected from the nozzle port 24 immediately before the needle 23 closes, the fuel is not atomized when the flow area of the compressed air decreases due to a decrease in the opening area of the nozzle port 24 when the needle 23 closes. Then, 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 the first embodiment shown in FIG. 1, only the compressed air is ejected immediately before the needle 23 closes, so that no liquid fuel adheres around the nozzle port 24, and therefore the carbon There is no danger of deposition.

FIG. 3 shows a case where the air blast valve 20 is applied to a two-cycle engine, and fuel injection from the air blast valve 20 is started just before the air supply valve 5 is closed. During low engine load operation, the injected fuel collects around the spark plug 9 because the flow velocity of the fresh air A flowing into the combustion chamber 4 is low, and thus good ignition is performed. On the other hand, during high engine load operation, a strong loop scavenging is performed because the flow rate of fresh air A is high,
Moreover, since the injected fuel is carried along the inner wall surface of the combustion chamber 4 by the new air flow A flowing in a loop, a uniform air-fuel mixture is formed in the combustion chamber 4. As a result, high engine output can be secured.

Next, a second embodiment will be described with reference to FIGS. Referring to FIG. 4, a needle insertion hole 42 extending straight in a housing 41 of the air blast valve 40 is provided.
The needle insertion hole 42 is formed in the needle insertion hole 42.
A needle 43 smaller in diameter than 42 is inserted. At one end of the needle insertion hole 42, a nozzle port 44 is formed.
Is controlled by a valve section 45 formed at the tip of the needle 43. In this embodiment, as in the first embodiment, the nozzle port 44 is disposed in the combustion chamber. A spring retainer 46 is fixed to the needle 43, and a compression spring 47 is inserted between the spring retainer 46 and the housing 41.
The nozzle port 44 is normally closed by the valve portion 45 of the needle 43 by the spring force of the compression spring 47. A movable core 48 is always in contact with the end of the needle 43 on the side opposite to the valve portion 45 by the spring force of a compression spring 49, and a solenoid 50 for sucking the movable core 48 and a stator are provided in the housing 41. 51
Is arranged. When the solenoid 50 is energized, the movable core 48
Moves toward the stator 51, and as a result, the needle 43 moves in the direction of the nozzle port 44 against the spring force of the compression spring 47, so that the nozzle port 44 is opened. A compressed air introduction passage 52 is formed on the housing 41 opposite to the nozzle port 44 on the same axis as the axis A with the needle insertion hole 42. A strainer 53 is provided in the middle of the compressed air introduction passage 52, and the compressed air introduction passage 52 is communicated with the compressed air source. Movable core 48
FIG. 6 is an enlarged cross-sectional view of FIG. Referring to FIG. 6, on the outer peripheral surface of the movable core 48, a convex portion 48a having a cylindrical surface concentric with the movable core 48 is formed so as to protrude at a central angle of 90 degrees. Therefore, the axis A is located between the inner peripheral surface of the housing 41 and the outer peripheral surface of the movable core 48.
An air passage 54 extending in the direction is formed (see FIGS. 4 and 6).

Referring to FIG. 7, a through hole 51a having a larger diameter than the needle 43 is formed in the stator 51 along the axis A, and an air passage 55 is formed between the needle 43 and the through hole 51a. You. A compression spring 47 is provided in the housing 41 below the stator 51.
Is formed, and the air passage 55 communicates with the spring chamber 57. The outer diameter of the upper portion 51b of the stator 51 is small, and an air passage 56 is formed on the outer peripheral side surface of the upper portion 51b. In the upper part 51b of the stator, a communication hole 51c is provided in the diameter direction.
Are formed to communicate the air passages 55 and 56. Therefore, the compressed air introduction passage 52 is communicated with the spring chamber 57 through the air passages 54 and 56, the communication hole 51c, and the air passage 55 (see FIGS. 4 and 7). Therefore, these air passages 54, 55, 56
The communication hole 51c and the spring chamber 57 are filled with compressed air.

Referring to FIGS. 4 and 5, the needle 43 has a large diameter portion 43a extending substantially in the direction of the axis A substantially at the center, and the large diameter portion 43a slides into the needle insertion hole 42a below the spring chamber 57. Mated as possible. Therefore, the compressed air that has reached the inside of the spring chamber 57 hardly flows out of the gap between the needle large diameter portion 43a and the needle insertion hole 42a.

On the other hand, a cylindrical nozzle chamber 58 having an axis B parallel to the axis A is formed in the housing 41. The lower portion 58c of the nozzle chamber 58 has a smaller diameter than the upper portion 58d. The lower end 58a of the nozzle chamber 58 is made to communicate with the inside of the needle insertion hole 42 below the large diameter portion 43a of the needle via a straight compressed air outflow passage 59. The compressed air outflow passage 59 extends obliquely with respect to the needle insertion hole 42 toward the nozzle port 44.
The compressed air outlet passage 59 is obliquely connected to the nozzle chamber 58 at an angle slightly larger than 90 degrees, for example, about 110 degrees. Reference numeral 60 denotes a blind plug for sealing one end of the compressed air outflow passage 59. The side surface 58b of the nozzle chamber 58 communicates with the spring chamber 57 via the compressed air inflow passage 61. The compressed air inflow passage 61 extends straight from the nozzle chamber side surface 58b in the direction perpendicular to the axis B, bends upward, and is obliquely connected to the spring chamber 57. An injection port 63 of the fuel injection valve 62 is arranged in the nozzle chamber 58,
Further, the injection port 63 is located between the lower end 58a and the side surface 58b in the nozzle chamber 58. The fuel injection valve 62 is arranged coaxially with the axis B. The injection port 63 is also disposed on the axis B, and fuel having a small divergence angle is injected from the injection port 63 along the axis B. Therefore, the fuel injected from the fuel injection valve 62 is supplied to the compressed air outflow passage 59.
It collides vigorously with the inner wall surface, whereby the emulsification of the injected fuel is rapidly performed.

FIG. 8 is a plan view of the housing 41 from which the assembled components above the housing 41 and the needle 43 and the like have been removed.
Referring to FIG. 8, the compressed air outflow passage 59 is formed along an axis C connecting the axis A and the axis B. On the other hand, the compressed air inflow passage 61 is formed along the axis D. This axis D
Is a tangent to the outer peripheral side surface of the nozzle chamber 58 through the axis A. Thus, the opening area of the compressed air inflow passage 61 to the nozzle chamber 58 can be increased.

Referring again to FIGS. 4 and 5, the needle insertion hole 42, the compressed air outflow passage 59, the nozzle chamber 58 and the compressed air inflow passage 61 are connected to the compressed air source 34 via the spring chamber 57 and the compressed air introduction passage 52. Is communicated to. Therefore, the needle insertion hole 42, the compressed air outflow passage 59, the nozzle chamber 58, and the compressed air inflow passage 61 are filled with compressed air. Fuel is injected into the compressed air from the injection port 63 along the axis B. Since the compressed air outflow passage 59 is obliquely connected to the nozzle chamber 58 at an angle slightly larger than 90 degrees (see FIG. 5),
The injected fuel collides with the inner wall surface of the compressed air outflow passage 59 and is rapidly emulsified. Most of the injected fuel adheres to the inner wall surface of the compressed air outflow passage 59 and the inner wall surface of the nozzle chamber 58. At this time, a small amount of fuel is accumulated in the nozzle port 44 at the tip of the needle 43. Next, when the solenoid 50 is energized, the needle 43 opens the nozzle port 44. As soon as the needle 43 opens the nozzle port 44, a small amount of fuel stored in the nozzle port 44 is ejected from the nozzle port 44 into the combustion chamber 4. When the needle 43 opens the nozzle port 44, the compressed air flows into the nozzle chamber 58 from the compressed air inflow passage 61,
Next, the air goes to the nozzle port 44 via the compressed air outflow passage 59.
At this time, the compressed air flowing through the nozzle chamber 58 and the compressed air outflow passage 59 atomizes the fuel adhering to the inner wall surface of the nozzle chamber 58 and the compressed air outflow passage 59, and mixes the fuel with the fuel toward the nozzle port 44. It is carried away and squirts from the nozzle port 44. Therefore, immediately after the opening of the needle 43, the nozzle port
A small amount of liquid fuel accumulated in 44 is pushed out from the nozzle opening 44 by the compressed air, but immediately after that, the fuel spray atomized and well mixed with the air is injected into the nozzle opening 44.
It is blown out from. That is, from the initial stage of the injection start in which the needle 43 opens the nozzle port 44 to inject fuel and air, fuel atomized and well mixed with air can be ejected from the nozzle port 44, and a good air-fuel mixture can be obtained. Can be formed. Further, the compressed air inflow passage 61 is provided in the nozzle chamber 58.
Compressed air flows through the nozzle chamber 58
Flows while turning along the inner peripheral wall of the. Therefore, the fuel attached to the inner peripheral wall surface of the nozzle chamber 58 can be satisfactorily carried away. When the needle 23 is opened, all of the injected fuel is ejected from the nozzle port 24. When the ejection of all the injected fuel is completed, only the compressed air is ejected from the nozzle port 24. Next, the solenoid 50 is deenergized, and the needle 43 closes the nozzle port 44, and operates in the same manner as in the first embodiment. In this embodiment, the same effects as in the first embodiment can be obtained.

FIG. 14 shows the measured fuel injection amount from the fuel injection valve 62,
The relationship with the flow rate of air ejected from the nozzle port 44 is shown. Conventionally, when most of the fuel measured by the fuel injection valve 62 is stored in the nozzle port 44, the fuel is pushed out from the nozzle port 44 in a liquid state by air pressure,
At the beginning of the fuel injection from the nozzle port 44, the atomization of the fuel and the mixing with the air were not good. Further, since the air does not flow out from the nozzle port 44 until the fuel is pushed out, the air flow rate tends to decrease as the fuel injection amount increases, as shown in FIG. In the present embodiment, fuel hardly accumulates in the nozzle port 44, and after a small amount of liquid fuel in the nozzle port 44 is pushed out from the nozzle port 44, the air flow path is not blocked by the fuel, and the air accompanies the fuel. Can flow out from the nozzle port 44. Therefore, as shown in FIG. 14, the air flow rate hardly changes depending on the fuel injection amount, and the relative flow rate of the air flow rate can be reduced as compared with the related art as shown by the dashed line.

The shapes, arrangements, and the like of the compressed air inflow passage 61, the nozzle chamber 58, and the compressed air outflow passage 59 are not limited to the present embodiment, and for example, embodiments shown in FIGS. 9 to 13 can be considered.

In the embodiment shown in FIG. 9, the compressed air inflow passage 61 is
It is formed in the same manner as in the embodiment. The compressed air outflow passage 59 is
The axis C is formed so as to pass through the axis B and be tangent to the outer peripheral side surface of the needle insertion hole 42. Thereby, the opening area of the compressed air outflow passage 59 to the needle insertion hole 42 can be increased.

In the embodiment shown in FIG. 10, the compressed air outflow passage 59 is
It is formed in the same manner as in the embodiment. Two compressed air inflow passages 61 are formed symmetrically with respect to the axis C. Compressed air inflow passage
61 is a parallel passage 61a formed along a straight line parallel to the axis C and along the axis E which is a tangent to the outer peripheral side surface of the nozzle chamber 58;
A radial passage 61b extending substantially in the radial direction of the spring chamber 57. In this embodiment, the swirling flow does not occur in the nozzle chamber 58 because the compressed air flowing into the nozzle chamber 58 flows from opposite directions and collides with each other. Therefore, the flow of the compressed air can be improved.

In the embodiment shown in FIG. 11, the compressed air outflow passage 59 is
It is formed in the same manner as in the above embodiment. The compressed air inflow passage 61 is formed so as to overlap the axis of the compressed air outflow passage 59 coaxially.

In the embodiment shown in FIG. 12, the lower portion 58c and the upper portion 58d of the nozzle chamber 58 have the same diameter.

In the embodiment shown in FIG. 13, the compressed air outflow passage 59 makes 90 degrees and is connected to the nozzle chamber 58. In this embodiment, the emulsification of the fuel can be further promoted as compared with the second embodiment.

[Effect of the invention]

All the fuel injected from the fuel injection valve is ejected together with the compressed air, so the injected fuel amount does not vary,
Thus, stable combustion can be ensured.

[Brief description of the drawings]

FIG. 1 is a partial sectional side view of an air blast valve of the first embodiment, FIG. 2 is a bottom view of an inner wall surface of a cylinder head, FIG. 3 is a side sectional view of a two-cycle engine, and FIG. FIG. 5 is a partial cross-sectional side view of the air blast valve of the embodiment of FIG. 5, FIG. 5 is an enlarged view of a main part of FIG. 4, FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 4, and FIG. Enlarged view of the vicinity of the stator, Fig. 8 to 11
The figure is a plan view of the housing with the upper part of the housing removed, FIG. 8 is a view showing the second embodiment, and FIGS.
FIGS. 12 and 13 show other different embodiments.
The figure is a view corresponding to FIG. 5, showing different embodiments.
FIG. 14 is a diagram showing a relationship between a fuel injection amount and an air flow rate. 20,40 ... Air blast valve, 22,42 ... Needle insertion hole, 23,43 ... Needle, 24,44 ... Nozzle port, 30,50 ... Solenoid, 32,58 ... Nozzle chamber, 33, 61 ... compressed air inflow passage, 34 ... compressed air source, 35,59 ... compressed air outflow passage, 36,62 ... fuel injection valve, 37,63 ... nozzle.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Manabu Tateno 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Takataka Cho, 1-1, Showa Town, Kariya City, Aichi Nippon Denso Co., Ltd. (56) References JP-A-61-104154 (JP, A) JP-A-63-65168 (JP, A) Actually open 1-118158 (JP, U) Actually open 56-35555 (JP, U) Special Table 1-503554 (JP, A) Special table Sho 63-500323 (JP, A)

Claims (1)

(57) [Claims] 1. A needle port is formed at one end of a needle insertion hole by inserting a needle smaller in diameter than the needle insertion hole into the needle insertion hole and electromagnetically controlling the needle. The nozzle port is controlled to open and close by the valve portion, and the compressed air passage connected to the compressed air source is connected to the needle insertion hole obliquely to the needle insertion hole, and the compressed air passage and the needle are connected on the side opposite to the nozzle port. A fuel injection device for an internal combustion engine, wherein an enlarged portion that closes a cross section of the needle insertion hole is formed on a needle adjacent to a communication portion of the insertion hole, and a fuel injection valve is arranged in the compressed air passage.