JPH1122470A - Fuel injection device of lean burn engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve super-lean air-fuel ratio driving at the time of a light load while maintaining the maximum output at the time of lean air-fuel ratio driving of an engine. SOLUTION: A first and second suction valves 51, 52 and a first and second suction ports 510, 520 are provided on each cylinder 1 of an engine, the inside of the second suction port is divided into two suction passages 521 and 522 by a bulkhead 525 extensively provided in a direction of a valve stem 52c of the suction valve 52, and suction control valves 551, 552 to block the second suction port and the inside suction passage 521 at the time of lean air-fuel ratio driving are provided. A head end 525a of the bulkhead 525 is arranged to face against the valve stem 52c with a specified interval between them. Additionally, a nozzle hole 41 opened to the first suction port of a fuel injection valve 40 is directed to the neighbourhood of an ignition plug 60, a nozzle hole 42 opened to the inside suction passage 521 is directed between the valve stem 52c and a cylinder central shaft and they are devised to respectively inject fuel in their suction processes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel injection device for a lean burn engine.

[0002]

2. Description of the Related Art There is known a lean burn engine which generates an intake swirling flow (swirl) around a cylinder central axis in a cylinder to stably burn an air-fuel mixture leaner than a stoichiometric air-fuel ratio as a whole. ing. In these lean-burn engines, a swirl intake port for causing a swirl in the intake air flowing into the cylinder, a straight intake port for allowing the intake air to linearly flow into the cylinder, and a straight port connected to each cylinder of the engine. An intake control valve for closing the intake passage. When the engine is operated at a lean air-fuel ratio, the intake control valve is closed, and most of the intake air flows into the cylinder from the swirl port side, and strong swirl is generated in the cylinder. In addition, at the time of engine high-power operation, the intake control valve is opened, and most of the intake air flows from the straight port, so that the intake resistance is reduced.

[0003] In these engines, the swirl port usually has a helical projection in the port that gives a swirling speed component to the passing intake air flow. Is generating a swirl. That is, a vortex is generated in the intake flow passing through the swirl port by the helical projection, and the vortex grows in the cylinder to generate an in-cylinder swirl.
For this reason, in swirl ports with helical protrusions,
When trying to increase the swirl ratio to achieve ultra-lean combustion with an increased air-fuel ratio during lean operation, it is necessary to increase the size of the helical protrusion in the port and increase the vortex generated by the helical protrusion Occurs. However, when the size of the helical protrusion is set to be large, the intake resistance of the swirl port increases, so that the maximum intake air amount during lean air-fuel ratio operation (when intake is performed only from the swirl port) is limited, There is a problem that the maximum output in the lean air-fuel ratio operation decreases.

On the other hand, Japanese Unexamined Utility Model Publication No. 4-1669 discloses an engine having a first intake valve and a second intake valve in each cylinder, and a partition partitioning an intake port connected to the first intake valve in a vertical direction of a cylinder head. Discloses an intake device in which the intake passage is divided into two wide and narrow intake passages, and an injection hole of a fuel injection valve is provided in an inner wide intake passage (on the side of the second intake valve). In the intake device disclosed in the publication, during a lean air-fuel ratio operation, the second intake port following the second intake valve and the wide intake passage are closed by an intake control valve, and only the narrow intake passage of the first intake port enters the cylinder. The configuration is such that intake air flows in. In addition, fuel is injected from an injection hole that opens into the wide intake passage in the vicinity of the in-cylinder spark plug during the intake stroke.

By closing the intake control valve and allowing the intake air to flow into the cylinder from the narrow intake passage of the first intake port,
Intake air flows into the cylinder from the first intake valve in a tangential direction along the cylinder inner peripheral wall. Therefore, a swirl around the central axis is generated in the cylinder. Further, fuel is injected from the injection hole of the fuel injection valve disposed in the wide intake passage toward the ignition plug during opening of the intake valve. At this time, the wide intake passage is closed by the intake control valve, and no intake air flow occurs. Therefore, the injected fuel reaches the vicinity of the ignition plug in the cylinder from between the valve body and the valve seat of the opening intake valve without being diffused by the intake flow. For this reason, in the device of the publication, a rich air-fuel mixture layer is formed in the vicinity of the spark plug, and the air-fuel mixture is stratified in the radial direction in the cylinder by a synergistic effect with the in-cylinder swirl due to the intake air flow from the narrow intake passage. Stable lean air-fuel ratio combustion becomes possible.

[0006]

However, when fuel is injected directly toward the spark plug as in the apparatus disclosed in the above-mentioned publication, the operation is performed in a lean air-fuel ratio operation region with a relatively high load. This may cause problems such as smoldering of the spark plug. That is, in the device disclosed in the above publication, the fuel injected toward the wide intake passage reaches the vicinity of the spark plug without being diffused into the intake air flow. Directly arrives, and the plug may be soiled.

Further, when swirl is generated by causing intake air to flow from a narrow intake passage along a cylinder inner peripheral wall without providing a helical projection as in the apparatus disclosed in the above publication, it is necessary to set a large swirl ratio. It is necessary to increase the flow velocity of the intake air flowing from the narrow intake passage. For this reason, in the device of the above-mentioned publication, the flow area is reduced toward the downstream side of the narrow intake passage to increase the intake flow velocity. However, if the flow passage area of the narrow intake passage is reduced in this manner, the intake resistance increases, and a problem arises that the maximum intake air amount is limited as in the case of the helical projection.

SUMMARY OF THE INVENTION In view of the above problems, the present invention stratifies an air-fuel mixture in a cylinder without causing a problem such as contamination of an ignition plug, and performs ultra-lean combustion without limiting a maximum intake air amount during a lean air-fuel ratio operation. It is an object of the present invention to provide a fuel injection device for a lean burn engine that enables the fuel injection.

[0009]

According to the first aspect of the present invention, a first and second two intake valves are provided for each cylinder of the engine, and a first and second intake valves are provided following the first and second intake valves. A fuel injection device for a lean burn engine having a second intake port and a second intake valve extending in the second intake port to a vicinity of a second intake valve valve axis along an intake flow in the second intake port. A second intake port, an inner intake passage located on the first intake port side, and an outer intake passage located on the opposite side of the first intake port with respect to the inner intake passage.
A partition partitioning into two intake passages, an intake control valve for closing the inner intake passages of the first intake port and the second intake port when the engine is operated at a lean air-fuel ratio, and A fuel injection valve having two injection holes opened to an intake port and an inner intake passage of the second intake port, and performing fuel injection from the respective injection holes at least when the intake control valve is closed during an intake stroke. The partition wall is extended so that the center line of the second intake valve valve shaft is located on the second intake valve side end extension surface of the partition wall, and the second intake valve side end of the partition wall is provided. The part is opposed to the second intake valve valve shaft at a predetermined distance, and the first intake port side injection hole of the fuel injection valve injects fuel in the vicinity of the in-cylinder spark plug. And the second of the fuel injection valves
The fuel injection device of the lean burn engine is provided, in which the intake port side injection hole of (1) injects fuel in a direction between the valve shaft of the second intake valve and the cylinder center axis.

That is, in the first aspect of the present invention, the downstream end of the partition wall faces the second intake valve valve shaft at a predetermined distance, and the second intake valve valve shaft centerline is The partition is arranged so as to be located on the extension surface of the partition. For this reason, the intake air flowing directly into the cylinder from the outer intake passage formed by the partition wall flows into the cylinder without interfering with the valve shaft and forms a swirl in the cylinder.

A part of the intake air passing through the outer intake passage passes between the end of the partition wall and the second intake valve valve shaft, and flows into the cylinder from the inner intake passage. On the other hand, fuel injected from the second intake port side injection hole in a direction between the second intake valve valve shaft and the cylinder center axis is finely divided by the intake air passing between the end of the partition wall and the valve shaft. The gas flows into the cylinder and is further caught in the swirl in the cylinder. For this reason, the fuel injected from the second intake port side injection hole diffuses into the in-cylinder swirl to form a homogeneous mixture layer.

Further, fuel injected from the first intake port toward the vicinity of the spark plug forms a relatively rich mixture layer near the spark plug. For this reason, in the present invention, a relatively dense mixture layer formed around the ignition plug by the fuel injected from the first intake port side injection hole during the lean air-fuel ratio operation is injected from the second intake port side injection hole. A uniform lean mixture formed by the burned fuel forms a surrounding shape. For this reason, even when the swirl ratio is set to a relatively small value, a stable combustion speed can be achieved, and lean combustion can be achieved at a lower swirl ratio than before. Further, since the swirl ratio can be set relatively low, it is not necessary to increase the flow velocity by narrowing the vicinity of the cylinder inlet of the outer intake passage, so that it is possible to reduce the intake resistance at the time of lean air-fuel ratio combustion. For this reason, the maximum intake air amount increases, and it is possible to improve the maximum output during the lean air-fuel ratio operation.

According to the second aspect of the present invention, the second intake port side injection hole of the fuel injection valve further injects fuel while pointing toward the back surface of the second intake valve valve head. Item 1. A fuel injection device for a lean burn engine according to item 1 is provided. According to the second aspect of the present invention, the fuel injected from the second intake port side injection hole collides with the back surface of the second intake valve valve body umbilical portion and is finely divided. The particles further diffuse into the swirl in the cylinder while being further miniaturized on the airflow passing therebetween. For this reason, in the present invention, in addition to the effect of the first aspect, a finer and more homogeneous air-fuel mixture is generated in the swirl.

According to the third aspect of the present invention, the second intake valve side end of the partition and the second intake valve valve shaft with respect to the entire intake flow rate flowing into the cylinder from the outer intake passage. Between the end of the partition and the valve shaft of the second intake valve as the engine load increases when the intake control valve is closed. 2. The fuel injection device for a lean burn engine according to claim 1, further comprising an adjusting unit that increases a ratio of the intake air flow to be performed.

According to the third aspect of the present invention, the flow rate of the intake air flowing into the cylinder after passing between the end of the partition wall and the second intake valve valve shaft by the adjusting means during the lean air-fuel ratio operation depends on the engine load. Adjusted. That is, as the engine load increases, the proportion of the intake air flow passing between the end of the partition wall and the valve shaft increases, so that the resistance of the intake air passing through the outer intake passage as a whole is reduced. Therefore, when the engine load is large, the maximum intake air flow rate can be increased, and the maximum engine output during lean air-fuel ratio operation is improved. When the engine load is small, the ratio of intake air flowing into the cylinder through the space between the end of the partition wall and the valve shaft decreases. growing. Therefore, at the time of low load operation, the flow velocity of the intake air flowing into the cylinder from the outer intake passage can be maintained relatively high, and a decrease in the swirl ratio at the time of low load operation can be prevented.

According to the fourth aspect of the present invention, the adjusting means includes a movable plate rotatably attached to the second intake valve side end of the partition, and the intake control valve closing valve. 4. The fuel injection device for a lean burn engine according to claim 3, wherein the movable plate is rotated such that an interval between the movable plate end and the second intake valve valve shaft increases as an engine load increases. Is done.

According to the fourth aspect of the present invention, the adjusting means is constituted by a movable plate, and the movable plate is rotated so that the distance between the end of the movable plate and the valve shaft increases as the engine load increases. For this reason, the flow rate of intake air passing between the end of the partition wall and the valve shaft increases as the engine load increases. According to the invention described in claim 5, the adjusting means further rotates the movable plate to a position where the cross-sectional area of the outlet of the outer intake passage is reduced during a light load operation of the engine. 3. A fuel injection device for a lean burn engine according to (1), is provided.

According to the fifth aspect of the present invention, when the engine is lightly operated, the movable plate narrows the outlet portion of the outer intake passage. Therefore, in addition to the operation of the third aspect, the intake air flowing directly into the cylinder from the outer intake passage is further provided. Flow velocity is increased. For this reason, the swirl ratio in the cylinder increases when the engine is lightly loaded, the turbulence in the cylinder increases, and a stable combustion speed can be obtained even when the fuel is ultra-lean at a light load.

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 are schematic views showing one embodiment of a fuel injection device to which the present invention is applied. 1 and 2, reference numeral 10 denotes a cylinder head of the engine. In this embodiment, a multi-cylinder engine is used, but FIGS. 1 and 2 show only one cylinder.

1 and 2, reference numeral 1 denotes a cylinder of an engine, and reference numeral 3 denotes a combustion chamber in the cylinder 1. In the present embodiment, as shown in FIG. 1, the combustion chamber 3 is provided with two intake valves 51 and 52 and two exhaust valves 71 and 72, and has a so-called four-valve configuration. Also, designated by 510 and 520 in FIG. 1 are first and second intake ports provided in the cylinder head 10 and connected to the first and second intake valves 51 and 52, respectively.

In this embodiment, the first intake port 510
Is a normal straight port that allows the intake air to flow linearly into the cylinder 1, and the second intake port 520 generates an intake swirling flow (swirl) around the cylinder center axis in the cylinder 1 by the inflowing intake air. It is a swirl port. In the present embodiment, the second intake port 5
A partition 525 is provided inside 20. As shown in FIGS. 1 and 2, the partition 525 is disposed vertically in the intake port 520 (in the axial direction of the cylinder 1), and the partition 525 defines two intake passages 5 in the second intake port 520.
21 and 522. Hereinafter, the intake passage 521 on the first intake port 510 side of the intake passage formed in the second intake port 520 will be referred to as an inner intake passage for convenience.
Intake passage 52 remote from first intake port 510
2 is called an outside intake passage. The partition wall 525 is provided over the entire length of the second intake port 520 in the length direction. The partition wall 525 allows the intake air flowing through the inner intake passage 521 and the outer intake passage 522 to be smoothly guided to the second intake valve 52. It extends along. Further, the downstream end portion 525a (the intake valve 52 side) of the partition 525 is connected to the second intake valve 52.
The valve body 52a extends to a position facing the valve shaft 52c at an interval. In the present embodiment, the partition 525 extends substantially linearly in the second intake port 520,
As shown in FIG. 3, the central axis 52d of the valve shaft 52c of the intake valve 52 is located on a plane extending the partition 525 toward the end 525a. Also, as shown in FIG. 3, near the end 525a, the thickness of the partition 525 is
It is smaller than the diameter of c.

In this embodiment, the cylinder head 10
The fuel injection valve 40 is disposed below the first and second intake ports 510 and 520. The fuel injection valve 40
The two main bodies are provided with two injection ports, and the injection ports are connected to a first injection port 41 opened to a first intake port 510 and a second injection port.
And the second injection hole 42 opened in the inner intake passage 521 of the intake port 520. In the present embodiment, during the lean air-fuel ratio operation, fuel is injected from the fuel injection valve 40 in the latter half of the intake stroke. Further, the first injection hole 41 opened to the first intake port 510 has a spark plug disposed at the upper center of the cylinder 1 through a space between the valve body of the first intake valve 51 and the valve seat when the valve is opened. Orientation 60. Furthermore, the inner intake passage 5 of the first intake port
The second injection hole opened to 21 is directed between the central axis of the cylinder 1 and the valve shaft 52c of the second intake valve 52, and in the present embodiment, the valve element of the second intake valve 52 when the valve is opened. 52
The umbrella part of a is oriented toward the back.

In this embodiment, the first intake port 510
Inner intake passage 521 of inlet and second intake port 520
Are provided with intake control valves 551 and 552, respectively. The intake control valves 551 and 552 are each configured as a butterfly valve having a plate-shaped valve body, and are closed when the engine operates at a lean air-fuel ratio to close the inside of the first intake port 510 and the inside of the second intake port 520, respectively. The intake passage 521 is closed. Therefore, when the engine is operating at a lean air-fuel ratio, the intake air flows into the cylinder 1 from the second intake valve 52 only through the intake passage 522 outside the second intake port 520. As described above, the outer intake passage 522
Is formed on the valve body 5 of the second intake valve 52.
Since the valve shaft 52a of 2a is extended in the direction coinciding with the central axis 52d, most of the intake air passing through the outer intake passage 522 is closer to the cylinder inner peripheral wall surface than the valve shaft 52c of the second intake valve 52. Cylinder 1 linearly downwards slightly
Flows into. Therefore, during the lean air-fuel ratio operation, the intake air flows from the second intake valve 52 into the cylinder from the tangential direction to the cylinder inner peripheral wall surface and rotates along the cylinder inner peripheral wall surface. Therefore, during the lean air-fuel ratio operation, the second
Of the cylinder 1 by the intake air flowing from the intake valve 52 of the cylinder 1
A strong swirl is formed around the central axis of the cylinder.

Further, in this embodiment, since the end 525a of the partition 525 faces the valve shaft 52c of the second intake valve 52 at a predetermined interval, the outer intake passage 522 is closed during the lean air-fuel ratio operation. Part of the intake air passing through is the partition end 5
From the gap between the valve shaft 25a and the valve shaft 52c, it goes around the outlet side of the inner intake passage 521, passes from the second intake valve 52 to the inside of the valve shaft 52c (the side closer to the first intake valve 51), and It will flow into. On the other hand, fuel is injected from the injection hole 42 opening into the inner intake passage 522 toward a portion inside the valve shaft 52c on the back surface of the valve body 52a, so that the fuel injected from the injection hole 42 is 5
It collides with the above-mentioned part of 2a and is atomized.

Further, since the intake air flowing through the space between the partition wall end 525a and the valve shaft 52c passes through the portion inside the valve shaft 52c on the back surface of the valve body 52a umbrella, the particles are atomized by collision with the valve body. The fuel thus collected is carried by the intake flow and further atomized, merges with the swirl generated in the cylinder, and diffuses into the swirl. In addition, fuel is injected from the first injection hole 41 on the side of the first intake port 510 toward the vicinity of the ignition plug 60 in the cylinder, and a relatively dense mixture layer is formed near the ignition plug.

FIG. 4 is a diagram schematically showing the behavior of the fuel injected from the first injection hole 41 and the second injection hole 42. That is, as shown in FIG. 4, during the lean air-fuel ratio operation, a uniform lean mixture layer LF in the swirl surrounds a relatively rich mixture layer RF formed near the ignition plug 60 in the cylinder 1. Become. For this reason, even if the swirl ratio is set high and the turbulence in the cylinder is not amplified, the flame is smoothly propagated from the rich mixture layer to the lean mixture layer, and a stable combustion speed can be obtained in the cylinder. .

FIG. 5 schematically shows the flow in the cylinder 1 at each stage from the intake stroke to the compression stroke when the intake control valves 551 and 552 are closed. Fig. 5 (A)
Indicates the state in the cylinder at the beginning of the intake stroke. FIG.
Since each of the figures shows a state in which the intake control valves 551 and 552 are closed, the intake valves 51 and 52 are initially set in the intake stroke.
Is opened, the intake air flows into the cylinder 1 only from the second intake valve 52. Piston 19 at the beginning of intake stroke
The air flow in the cylinder is disturbed due to the lowering of FIG. 5 (A), and the intake air flowing into the cylinder 1 through the intake valve 52 from the outside intake passage 522 of the second intake port is stabilized in the cylinder. Swirl cannot be generated.
However, in the latter half of the intake stroke, the descending speed of the piston 19 gradually decreases, so that the intake air flowing from the outer intake passage 522 into the cylinder 1
2 is generated around the center axis of the cylinder, and a stable and strong swirl flow S is generated in the cylinder 1 in the latter half of the intake stroke as shown in FIG. 5 (B). Generated. The swirl flow S has a high flow velocity near the inner peripheral surface of the cylinder, but its velocity in the circumferential direction decreases as approaching the cylinder central axis, and there is a region Sa near the cylinder central axis where almost no intake air flows. Fuel injection from the injection holes 41 and 42 is performed in the latter half of the intake stroke in which the strong swirl flow S is generated.

In this case, as described above, the fuel injected from the injection hole 42 on the side of the second intake port 520 collides with the back surface of the second intake valve valve body 52a umbrella, and the second intake valve 52 Then, the air flows into the cylinder while being miniaturized and diffused by the intake air flowing through the inside of the valve shaft 52c, and rides on the swirl S together with the intake air, and turns in the cylinder together with the swirl flow. Therefore, a uniform lean mixture is formed in the swirl.

On the other hand, the injection hole 4 on the first intake port 510 side
From 1, fuel is injected near the spark plug, that is, toward the central region Sa where the swirl S does not flow. Also,
In the present embodiment, the injection hole 42 is opened at a position near the upper part of the valve seat of the first intake valve 51, and further, when the intake control valve 551 is closed, there is no intake flow passing through the first intake port 510. Therefore, the fuel injected from the injection hole 41 is diffused by the intake air flow, does not collide with the intake valve, passes through the narrow gap between the intake valve during valve opening and the valve seat, and directly passes through the central region of the swirl S. Reach Sa. Also,
Since the injection hole 42 is directed to the vicinity of the ignition plug, the injection hole 4
The fuel injected from 2 reaches the swirl center region Sa in the upper part of the cylinder and stays there to form a rich mixture layer.

When the intake stroke ends and the piston 19 rises, an upward airflow U is generated in the cylinder 1 with the rise of the piston as shown in FIG. 5 (C). The rich air-fuel mixture layer that has accumulated in the swirl central region in (B) is further concentrated near the upper center of the combustion chamber. Therefore, near the ignition timing in the latter half of the compression stroke, the rich mixture layer is concentrated near the ignition plug, and a uniform lean mixture layer surrounds the layer. For this reason, ignition of the rich mixture layer by the ignition plug is easily performed, and when ignition occurs in the rich mixture layer, the flame is also stably diffused into the lean mixture layer uniformly diffused in the cylinder by the swirl. Propagation occurs and combustion occurs in the entire combustion chamber.

In addition, according to the present embodiment, the outer intake passage 522 generates swirl by introducing intake air linearly in the tangential direction into the cylinder. And the maximum intake air amount during the lean air-fuel ratio operation can be set large. For this reason, the maximum engine output at the time of the lean air-fuel ratio operation increases, and it becomes possible to perform the lean air-fuel ratio operation to a higher engine load region than before.

As described above, the fuel injection device according to the present embodiment has the following characteristic configuration. The second intake valve 5 is provided in the second intake port 520.
A partition 525 extending toward the center line of the two valve shafts is arranged. The end 525a of the partition 525 is the valve shaft 52 of the valve 52.
It is arranged so as to face c with an interval.

In the lean air-fuel ratio operation, intake control valves 551 and 552 for closing the first intake port 510 and the inner intake passage 521 of the second intake port are provided. A fuel injection valve 40 having two injection holes 41 and 42 is provided, and fuel is injected from the injection hole 41 opening into the first intake port 510 in a direction near the ignition plug in the cylinder, and the second intake Fuel is injected from a second injection hole opened in the intake passage 522 inside the port in a direction between the valve shaft 52c of the second intake valve 52 and the cylinder center axis.

With the above configuration, the outer intake passage 52
2, the intake air flows linearly in the tangential direction into the cylinder during the lean air-fuel ratio operation, and swirl is generated. As a result, the intake resistance of the intake passage is reduced as compared with the case where the helical projection is used as in the conventional case, and the maximum intake air amount during the lean air-fuel ratio operation can be set large. The maximum engine output at the time increases,
Lean air-fuel ratio operation can be performed up to a higher engine load region than before.

Further, with the above arrangement, the fuel injected from the second injection hole diffuses uniformly in the swirl flow to form a lean mixture, and the fuel injected from the first injection hole This stabilizes the propagation of flame from the rich mixture formed around the spark plug. Therefore, the combustion during the lean air-fuel ratio operation is stabilized, and the lean limit (the maximum air-fuel ratio that can be operated stably) increases.

Further, with the above configuration, the fuel injection valve 4
Part of the fuel injection from 0 is used to form a rich mixture layer around the plug, and the rest is used to form a uniform lean mixture. Therefore, even when the load is relatively high and the fuel injection amount is correspondingly large, the entire amount of fuel is not concentrated around the ignition plug, so that the plug is not contaminated. next,
Another embodiment of the present invention will be described with reference to FIGS.

FIGS. 6 and 7 show FIGS. 1 and 2 of the above embodiment.
1 and 2, and the same reference numerals as those in FIGS. 1 and 2 indicate the same elements. In this embodiment, the downstream end 525a of the partition 525 in the embodiment of FIG. 1 is configured as a movable plate rotatable around an axis parallel to the valve shaft 52c of the second intake valve 52. Figure 1
Is different from the embodiment of FIG.

That is, in FIG. 6 and FIG.
5 A rotary shaft 525b is provided at an upstream portion of the distal end portion 525a, and a partition wall portion from the distal end portion 525a to the rotary shaft 525b is configured as a movable plate 526 rotatable around the rotary shaft 525b. ing. Further, the movable plate 526 is configured to rotate according to the engine load by an appropriate type of actuator such as a motor and a negative pressure actuator (not shown).

FIG. 8 is a diagram for explaining the adjustment of the position of the movable plate 526 according to the engine load in the present embodiment. In the present embodiment, for example, in a light load operation at the time of the lean air-fuel ratio operation, the movable plate 526 is rotated to a position indicated by reference numeral I in FIG. When the movable plate 526 moves to the position indicated by I, the flow rate of the intake air flowing into the cylinder 1 from the outer intake passage 522 increases, so that the swirl ratio of the swirl flow generated in the cylinder (the swirl ratio during one rotation of the engine). The number of times the flow rotates in the cylinder). Therefore, during light load operation, it is possible to achieve a stable ultra-lean combustion (for example, an air-fuel ratio of about 35) by setting the air-fuel ratio high.

For example, in a medium load operation at the time of a lean air-fuel ratio operation, as shown by reference numeral II in FIG.
Is set in the direction of the valve shaft 52c of the second intake valve 52, that is, in a position on the extension of the partition wall 525. Thereby, the same effect as that of the embodiment shown in FIG. 1 is obtained, and the lean air-fuel ratio operation (for example, about 30 at the air-fuel ratio) with a high air-fuel ratio can be stably performed in a wide load region with a moderate load. It becomes possible.

In a high-load operation (for example, an operation at an air-fuel ratio of about 25) during a lean air-fuel ratio operation, the movable plate 526
As shown by the reference numeral III in FIG. 8, the valve rotates toward the inner intake passage 521 so that the distance between the valve shaft 52c and the tip 525a of the movable plate increases. As a result, the intake air flow passing between the valve shaft 52c and the distal end portion 525a is further increased as compared with the case of the embodiment shown in FIG.
The resistance of the intake air passing through 22 will be further reduced compared to the embodiment of FIG. For this reason, the maximum intake air amount at the time of high load operation further increases as compared with the embodiment of FIG. 1, and the maximum output at the time of lean air-fuel ratio operation further increases.

In this embodiment, when the lean air-fuel ratio operation is not performed, that is, when the intake control valves 551 and 552 are open, the movable plate 526 is arranged at the position II in FIG. As a result, the movable plate 526 is connected to the inner passage 52.
First, since both of the outer passages 522 are arranged at positions where the intake resistance is minimized, the second intake port 520
It is possible to maintain a large amount of intake air passing through.

[0043]

According to the invention described in each of the claims, ultra-lean combustion can be performed without increasing the maximum output during lean air-fuel ratio operation without causing the spark plug to be fouled during high load operation as described above. It is possible to achieve an excellent effect that can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an embodiment of a fuel injection device of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of an embodiment of a fuel injection device of the present invention.

FIG. 3 is a view for explaining an extending direction of a partition wall in a second intake port.

FIG. 4 is a diagram illustrating the operation of the embodiment of FIG. 1;

FIG. 5 is a diagram illustrating the operation of the embodiment of FIG. 1;

FIG. 6 is a view similar to FIG. 1, illustrating another embodiment of the present invention.

FIG. 7 is a view similar to FIG. 2, illustrating another embodiment of the present invention.

FIG. 8 is a diagram for explaining the operation of the embodiment of FIGS. 6 and 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylinder 51 ... 1st intake valve 52 ... 2nd intake valve 52c ... Valve shaft 510 ... 1st intake port 520 ... 2nd intake port 521 ... Inner intake passage 522 ... Outer intake passage 525 ... Partition wall 551, 552 ... intake control valve

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 41/02 310 F02D 41/02 310G 45/00 301 45/00 301G F02M 69/00 360 F02M 69/00 360B 69/04 69 / 04 R

Claims (5)

[Claims] 1. A fuel injection system for a lean burn engine having first and second two intake valves in each cylinder of the engine, and first and second intake ports following the first and second intake valves. Wherein the first intake port extends in the second intake port along the intake flow in the second intake port to the vicinity of the second intake valve valve shaft, and the first intake port extends through the second intake port. A partition partitioning into two intake passages, an inner intake passage located on the port side, and an outer intake passage located on the opposite side of the first intake port with the inner intake passage interposed therebetween; An intake control valve for closing the first intake port and the inner intake passage of the second intake port when the first intake port and the second intake port are opened. Have two orifices, from each of which A fuel injection valve that injects fuel during an intake stroke at least when the intake control valve is closed, wherein the partition has a second intake valve valve axis center line extending from a second intake valve side end extension surface of the partition. A second intake valve side end of the partition wall is opposed to the second intake valve valve shaft at a predetermined distance, and the first end of the fuel injection valve The intake port side injection hole injects fuel in a direction directed to the vicinity of the in-cylinder ignition plug, and the second intake port side injection hole of the fuel injection valve has a valve axis of the second intake valve and a cylinder center axis. A fuel injection device for lean-burn engines that injects fuel in a direction between them. 2. The lean burn engine according to claim 1, wherein the second intake port side injection hole of the fuel injection valve further injects fuel in a direction toward the back surface of the second intake valve valve head. Fuel injection device. 3. An engine according to claim 1, further comprising: a passage between the second intake valve side end of said partition wall and a second intake valve valve shaft for an entire intake flow rate flowing into said cylinder from said outer intake passage. To adjust the ratio of the intake air flow passing between the end of the partition and the second intake valve valve shaft as the engine load increases when the intake control valve is closed. The fuel injection device for a lean burn engine according to claim 1, further comprising a means. 4. The adjusting means comprises a movable plate rotatably attached to an end of the partition wall on a second intake valve side, and when the intake control valve is closed, the movable plate increases as the engine load increases. 4. The fuel injection device for a lean burn engine according to claim 3, wherein the movable plate is rotated so that an interval between the plate end and the second intake valve valve shaft is increased. 5. The lean-burn engine according to claim 4, wherein said adjusting means further rotates said movable plate to a position where a flow path cross-sectional area of said outer intake passage outlet portion is reduced during a light load operation of said engine. Fuel injector.