JP2001055925A - Intake controlling device for direct injection type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize stable combustion in respective combustion modes by properly controlling a normal tumble flow according to the respective combustion modes. SOLUTION: This device has a partition 18 partitioning an intake port 15 into an upper port part 15a and a lower port part 15b, and a tumble control valve 19 selectively throttling the upper and lower port parts 15a, 15b to control a normal tumble flow (T1) generated in a combustion chamber 17. The lower port part 15b is throttled in time of stratified combustion corresponding to a low load, the upper port part 15a is throttled in time of uniform lean combustion corresponding to a middle load, and either of the upper and lower port parts 15a, 15b is not throttled in time of uniform theoretical air-fuel ratio combustion corresponding to a high load.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a four-cycle type direct injection type internal combustion engine represented by an automobile gasoline engine and the like, and more particularly, to a forward tumble flow generated in a combustion chamber at an intake port of each cylinder. The present invention relates to an intake control device provided with a tumble control valve for adjusting.

[0002]

2. Description of the Related Art At medium and high loads, a homogeneous air-fuel ratio mixture is formed in a cylinder to perform so-called homogeneous combustion, and at a low load region, the mixture is relatively dense only in a part of the cylinder, that is, only near a spark plug. Performs stratified combustion to form an air-fuel mixture and achieves a very high average air-fuel ratio, and achieves both medium- and high-load output performance by homogeneous combustion and improved fuel efficiency at low-load by stratified combustion. Various direct injection type internal combustion engines have been proposed in the past.

As an example, in a direct injection type internal combustion engine described in Japanese Patent Application Laid-Open No. 9-256858, a partition partitioning an intake port into a forward tumble port portion and a reverse tumble port portion, and a control valve for narrowing the forward tumble port portion are provided. Is provided. The shape of the forward and reverse tumble ports and the control of the operation of the control valve cause the intake air flowing into the cylinder to descend along the cylinder wall on the exhaust side during homogeneous combustion, and then return to the piston top surface and the cylinder wall on the intake side. Generates a forward tumble flow that flows to the cylinder head side, and at the time of stratified combustion, the intake flow flowing into the cylinder descends along the cylinder wall of the intake side by narrowing the forward tumble port portion. Later, a reverse tumble flow which flows along the top surface of the piston and the cylinder wall surface on the exhaust side and travels toward the cylinder head side is generated, and the mixture is stratified.

[0004] As another example of the intake control device that generates the flow by switching between the forward tumble flow and the reverse tumble flow, as described in JP-A-10-205338,
A technique of providing a sub-intake pipe for energizing a part of the intake air flow, or, as described in JP-A-10-212965, a part of a passage is shielded near an opening of an intake port on a combustion chamber side. A technique for providing a tumble control valve is known.

The intake control device for a direct injection type internal combustion engine described in US Pat. No. 5,878,712 includes a partition for dividing an intake port into an upper port portion and a lower port portion, and a tumble control valve for restricting the lower port portion. During homogeneous combustion, a forward tumble flow is generated by the upper and lower passages of the intake port, and at the time of stratified combustion, a lower port portion is throttled to generate a stronger forward tumble flow.

[0006]

Incidentally, even in the above-described operation region in which the homogeneous combustion is performed, at the time of a high load such as a full-open output, the homogeneous stoichiometric air-fuel ratio combustion near the stoichiometric air-fuel ratio is performed. Mainly for the purpose of improving fuel economy, desirably, homogeneous lean combustion with an air-fuel ratio larger than the stoichiometric air-fuel ratio is performed.

However, in the conventional intake control apparatus for a direct injection type internal combustion engine as described above, the rotation direction or intensity of the tumble flow is switched between stratified combustion and homogeneous combustion, but homogeneous lean combustion and homogeneous theory in homogeneous combustion are performed. It is not configured to switch the rotation direction or intensity of the tumble flow between the air-fuel ratio combustion. As a result, it is difficult to achieve both enhancement of flow during homogeneous lean combustion and securing of the amount of air during homogeneous stoichiometric air-fuel ratio combustion.

To explain this point in detail, as shown in FIG. 11, the shape of the intake port, that is, the intensity (tumble ratio) of the tumble flow and the flow rate (coefficient) of the intake air with respect to the inclination angle θ generally contradict each other. The tumble strength tends to decrease when the intake air amount is increased. For this reason, when trying to sufficiently secure the maximum output at the time of high engine load, the tumble strength at the time of medium load tends to be insufficient, the combustion at the time of homogeneous lean combustion deteriorates, and there is a possibility that sufficient fuel efficiency improvement cannot be obtained. .

Therefore, the above-mentioned Japanese Patent Application Laid-Open No. 9-256858 has been proposed.
JP, JP-A-10-205338, JP-A-10-205338
In the configuration using both the forward tumble flow and the reverse tumble flow as in JP-A-212965, in order to enhance the tumble flow during homogeneous lean combustion, the same reverse tumble flow as during stratified combustion in which a strong tumble flow is obtained. It is conceivable to apply the stream during homogeneous lean burn. However, in this case, due to the reverse tumble flow descending along the cylinder wall surface on the intake side, the fuel spray descends along the cylinder wall surface on the intake side, and the flammable mixture is unevenly distributed toward the intake side at the ignition timing. It is difficult to obtain burnt combustion.

On the other hand, in a configuration for adjusting the strength of forward tumbling flow as disclosed in US Pat. No. 5,878,712,
In order to enhance the tumble flow during homogeneous lean combustion, it is conceivable to apply the same configuration as during stratified combustion, in which a strong forward tumble flow is obtained, that is, the configuration that blocks the lower port portion of the intake port during homogeneous lean combustion. Can be However, in the case of such a configuration, as schematically shown in the comparative example of FIG. 9, the spray injected from the fuel injection valve also decreases due to the intake flow descending near the center of the cylinder during the intake stroke, Although the air-fuel mixture is diffused in a wider range than in the case of the air-fuel mixture formation by the reverse tumble flow described above, the air-fuel mixture is not diffused to the entire combustion chamber. For this reason, at the ignition timing, as shown schematically in FIG. 10, the air-fuel mixture is unevenly distributed on the intake side, and it is also difficult to obtain stable homogeneous lean combustion.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to produce a stratified fuel-air mixture during stratified combustion, a homogeneous lean-fuel mixture during homogeneous lean-burn, and a homogeneous stoichiometric air-fuel ratio combustion. It is an object of the present invention to provide a novel intake control device for a direct-injection type internal combustion engine, which can realize a sufficient amount of air at a high level and can significantly improve combustion performance.

[0012]

In the direct injection type internal combustion engine according to the present invention, a fuel injection valve for directly injecting fuel into the combustion chamber of each cylinder is disposed below the intake port, and when the engine is under a low load. Stratified combustion in which fuel is injected in the compression stroke, homogeneous lean combustion in which fuel is injected in the intake stroke at medium load, and homogeneous stoichiometric air-fuel ratio combustion in which fuel is injected in the intake stroke at high load are performed. ing.

[0013] The intake control apparatus according to the first aspect of the present invention includes a partition wall for partitioning an intake port into an upper port portion and a lower port portion, and a forward tumble flow generated in the combustion chamber. And a control means for controlling the operation of the tumble control valve in accordance with at least the engine load. The lower port is mainly throttled during stratified charge combustion, and the lower port is mainly homogenously diluted. It is characterized in that the upper port portion is throttled during combustion, and that neither the upper nor lower port portion is throttled mainly during homogeneous stoichiometric air-fuel ratio combustion.

With this configuration, the lower port portion is throttled mainly during stratified charge combustion, so that the proportion of intake air from the upper port portion increases. As a result, the forward tumble flow generated in the combustion chamber is appropriately strengthened, and becomes a small one that revolves around the center of the cylinder, which is suitable for stratification of the air-fuel mixture. More specifically, the fuel injected during the compression stroke is carried directly to the vicinity of the spark plug by an intake air flow (forward tumble flow) rising toward the spark plug after flowing along the piston crown surface, At the ignition timing, a combustible mixture is favorably formed near the spark plug.

Also, mainly during homogeneous lean combustion, the upper port portion is throttled, so that the proportion of intake air from the lower port portion increases. As a result, the forward tumble flow generated in the combustion chamber is appropriately strengthened and swirls over the entire combustion chamber of the cylinder, which is suitable for generating a homogeneous lean mixture. More specifically, the fuel injected in the intake stroke rides on the intake flow (forward tumble flow) introduced from the lower port portion near the fuel injection valve, and is diffused throughout the combustion chamber, and burns at the ignition timing. A good homogeneous lean mixture is formed in the room.

Further, at the time of homogeneous stoichiometric air-fuel ratio combustion, since neither the upper port nor the lower port is throttled, it is possible to secure a sufficient amount of intake air. In other words, the shape and dimensions of the intake port such as the inclination angle are set so as to ensure the maximum intake air amount under such a high load.

As a result, according to the present invention, it is possible to achieve both a high fuel consumption improvement effect by stratified combustion and homogeneous lean combustion and an increase in output by homogeneous stoichiometric air-twist ratio combustion at a high level.

As the tumble control valve, a general throttle valve can be used.
As in the invention, one butterfly valve is supported by the partition wall and can be held at a position where one of the upper port portion and the lower port portion is selectively throttled and a neutral position substantially along the partition wall. In this case, both the upper port portion and the lower port portion can be selectively throttled by one butterfly valve, so that the configuration and control can be simplified.

In a transition period between stratified combustion and homogeneous lean combustion or a transition period between homogeneous lean combustion and homogeneous stoichiometric air-fuel ratio combustion,
The throttle amounts of the upper and lower ports may be changed abruptly, but desirably, in order to suppress a decrease in combustion performance due to a delay in the operation of the tumble control valve in the transition period.
As in the invention, the throttle amount of the upper and lower ports is set to change relatively slowly in the transition period.

In addition, even if the engine load is the same, when the engine speed is relatively low, the flow velocity of the intake air becomes low, and the tumble flow generated in the combustion chamber becomes relatively weak. Conversely, when the engine speed is high, the flow velocity of the intake air increases, and the tumble flow is relatively enhanced. Therefore, preferably, the throttle amount of the upper and lower ports is changed according to the engine speed so that an appropriate tumble flow according to the engine speed is obtained.

Specifically, the throttle amount of the upper and lower ports is set to be smaller as the engine speed increases, as in the invention of claim 5.

Similarly, in the invention of claim 4, at least in the transitional period between the stratified combustion and the homogeneous lean combustion and the transitional period between the homogeneous lean combustion and the homogeneous stoichiometric air-fuel ratio combustion, the angular characteristics of the tumble control valve with respect to the engine load are determined. However, it is set to shift to the low load side as the engine speed increases.

[0023]

As described above, according to the present invention, by controlling the operation of the tumble control valve, the forward tumble flow generated in the combustion chamber can be appropriately adjusted according to each combustion mode. It is possible to achieve a high level of both the enhancement of the fuel efficiency improvement effect by the stratified combustion and the homogeneous lean combustion and the improvement of the output by the high-load homogeneous theoretical air-twist combustion.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which an intake control device according to the present invention is applied to a four-cycle type automobile gasoline engine which is a direct injection type internal combustion engine will be described in detail with reference to the accompanying drawings. .

As shown in FIG. 2, the cylinder block 2
0, a plurality of cylinders 13 are arranged in series,
The cylinder head 12 is fixed so as to cover the upper surface. A piston 14 is slidably fitted in the cylinder 13, and a pent roof type combustion chamber 17 is formed above the piston 14. A shallow dish-shaped recess 14 a is formed in the crown of the piston 14.

The cylinder head 12 is formed with an intake port 15 and an exhaust port 16 that open to the combustion chamber 17, and is provided with an intake valve 21 and an exhaust valve (not shown) that open and close the ports 15, 16. I have. Intake port 1
5 has an appropriate shape and dimensions so as to generate forward tumble flows T1 to T3 flowing in the clockwise direction as shown in FIGS.

At the top of each combustion chamber 17, the ignition plug 2 is arranged at a substantially central position of the cylinder 13, and the tip of the plug faces the combustion chamber 17. Further, the electromagnetic fuel injection valve 1 is disposed immediately below the intake port 15 with its central axis directed obliquely downward, so that the fuel is injected directly into the combustion chamber 17. The distal end faces the combustion chamber 17.

Each intake port 15 has the intake port 1
5 is divided into an upper port portion 15a and a lower port portion 15b, and a thin plate-shaped partition wall 18 is provided. At the upstream end of each partition wall 18, the upper port portion 15a and the lower port portion 15b are selectively provided. A butterfly valve-type tumble control valve 19 is pivotally supported, and the partition wall 18 and the tumble control valve 19 constitute a part of the intake control device of the present embodiment.

FIG. 1 shows a schematic configuration of the intake control device. Engine control unit (ECU) 4
Includes a tumble control valve angle sensor 11 for detecting the angle of a crank angle sensor 5, a cylinder discrimination sensor 6, a throttle sensor 7, an air amount sensor 8, a fuel pressure sensor 9, an air-fuel ratio sensor 10, and a tumble control valve 19. Various sensors for detecting the operating state of the engine are connected. The ECU 4
Based on signals from these sensors, the operation of the tumble control valve driving device 3 that drives the tumble control valve 19 as well as the fuel injection valve 1 and the spark plug 2 is controlled. That is, the ECU
4 calculates a required fuel injection amount according to an engine speed, a load, and the like, generates a required fuel pressure by a fuel pump (not shown), outputs an injector driving signal, controls fuel injection, and generates an ignition signal. The output is output to drive and control an ignition coil (not shown), and the ignition plug 2 is discharged to control ignition.
Further, the ECU 4 calculates the angle of the tumble control valve 19 based mainly on the engine load and the engine rotation speed, and controls the operation of the tumble control valve driving device 3.

FIG. 7 shows a state of homogeneous stoichiometric air-fuel ratio combustion performed at a high load such as a full-open output. At the time of such a high load, the tumble control valve 19 is arranged at a neutral position along the partition 18 in order to secure a sufficient intake air amount.
The tumble control valve 19 is set so that neither the upper port portion 15a nor the lower port portion 15b is throttled. As a result, the fuel injected during the intake stroke flows from both ports 15a and 15b of the intake port 15 into the combustion chamber 17.
By the forward tumble flow T3 of the intake flow introduced into the combustion chamber 17, the intake flow is uniformly diffused throughout the combustion chamber 17. In other words, the shape and dimensions of the intake port 15 such as the inclination angle are set so as to ensure the maximum intake air amount under such a high load.

FIGS. 2 to 4 show the state of the stratified charge combustion operation performed when the engine is under a low load, and show the states before and after the fuel injection in the compression stroke in order. During such stratified combustion, the tumble control valve 19 is connected to the lower port portion 15b.
Is set to be turned downward by 90 degrees from the neutral position shown in FIG. For this reason, as shown in FIG. 2, the intake air is mainly introduced into the combustion chamber 17 through the upper port portion 15a, and both ports 15a and 15b are not throttled as shown in FIG. The tumble flow T1 generated in the combustion chamber 17 is effectively strengthened and becomes relatively small in the center of the cylinder 13 as shown in FIG. Therefore, as shown in FIG. 3, the fuel injected in the compression stroke descends and the piston 1
On the tumble flow T1 which rises toward the spark plug 2 after flowing along the four crown surfaces, it is directly carried to the vicinity of the spark plug 2 and, as shown in FIG. Near the point, a good combustible mixture is formed in a layer around the spark plug. As a result, the recess 14a is substantially formed.
The combustion proceeds in the inside, and good stratified combustion is realized.

FIGS. 5 and 6 show a state of a homogeneous lean burn operation performed at a medium load of the engine. FIG. 5 shows a state of an intake stroke before fuel injection is performed, and FIG. 6 shows a state of the intake stroke after fuel injection. This shows the state of the compression stroke. At the time of such homogeneous lean combustion, the tumble control valve 19 is set at a position rotated 90 degrees above the neutral position, contrary to the case of the above-described stratified combustion, and the tumble control valve 19 causes the upper port 1 to rotate.
Most of 5a is narrowed down. As a result, the intake air is mainly introduced into the combustion chamber 17 through the lower port portion 15b, and the tumble flow T2 generated in the combustion chamber 17 is
The shape is effectively strengthened, and the shape of the cylinder 13 is largely swiveled throughout the cylinder 13. Accordingly, as shown in FIG. 6, the fuel injected during the intake stroke is uniformly dispersed on the tumble flow T2, and a good homogeneous lean mixture is generated in the entire combustion chamber 17.

Here, generally, as shown in FIG.
In accordance with the shape of the intake port 15, that is, the inclination angle θ, the intensity of the tumble flow generated by the intake port 15, that is, the tumble ratio, and the flow coefficient of the intake air introduced into the combustion chamber 17 from the intake port 15 are opposite to each other. The relationship is as follows. Therefore, as described above, when the inclination angle of the intake port 15 is set so as to satisfy the required amount of air at the time of high load, the tumble flow component tends to be insufficient particularly at the time of homogeneous lean combustion. However, in the present embodiment, at the time of homogeneous lean combustion, the tumble control valve 19 controls the upper port portion 15.
Since the tumble flow is effectively strengthened by reducing a, it is possible to eliminate the shortage of the tumble flow during homogeneous lean combustion.

Next, the difference between the case where the upper port portion 15a is closed and the case where the lower port portion 15b is closed, specifically, the difference in the forward tumble flow and the air-fuel mixture formed in the combustion chamber 17 will be described. This will be described in detail with reference to comparative examples shown in FIGS.

FIG. 8 shows the upper port 1 by the tumble control valve 19 during stratified combustion, contrary to the embodiment shown in FIGS.
An example in which 5a is narrowed down is shown. In this case, the intake air mainly flows into the combustion chamber 17 through the lower port portion 15b, and a tumble flow T4 swirling in the entire combustion chamber 17 is generated. For this reason, the fuel injected in the compression stroke rides on the intake flow (the tumble flow T4) that turns more greatly than the tumble flow T1, and is conveyed to the exhaust side.
As a result, as compared with the present embodiment shown in FIGS. 2 to 4, the time during which the air-fuel mixture stays in the vicinity of the spark plug 2, that is, the ignitable time, becomes shorter, and the stratified combustion becomes unstable.

In other words, in the present embodiment shown in FIGS. 2 to 4, the lower port portion 15b is throttled by the tumble control valve 19, and the intake air is supplied to the combustion chamber 17 by the upper port portion 15a relatively far from the fuel injection valve 1. With this configuration, a strong tumble flow can be generated in the central portion of the combustion chamber 17, the fuel does not flow toward the exhaust side due to the tumble flow immediately after entering the combustion chamber 17, and the piston 14 Tumble flow T from the crown surface to the spark plug 2 side
1, the fuel spray is directly carried to the vicinity of the spark plug 2, so that good stratified combustion can be realized.

FIGS. 9 and 10 show a comparative example in which the lower port portion 15b is throttled by the tumble control valve 19 during homogeneous lean combustion, contrary to the present embodiment shown in FIGS. In this case, the forward tumble flow T5 formed in the combustion chamber 17 becomes a small one that revolves around the center of the cylinder 13. Therefore, as schematically shown in FIG. 9, the fuel spray injected in the intake stroke falls on the tumble flow T5. Therefore, at the ignition timing shown in FIG. 10, the combustible air-fuel mixture is unevenly distributed to the intake side, and the combustion chamber 17
It does not diffuse well throughout, and the homogeneous lean burn becomes unstable.

FIGS. 12 to 15 show examples of map data defining the angle of the tumble control valve 19 with respect to the engine load (and the engine speed). Incidentally, the angle of the tumble control valve 19 is set to the two port portions 15a, as shown in FIG.
With reference to the neutral position where 15b is fully open, the downward rotation direction where the lower port portion 15b is throttled is defined as a positive direction, and the upward rotation direction where the upper port portion 15a is throttled is defined as a negative direction.

In the first embodiment shown in FIG. 12, the angle of the tumble control valve 19 surely becomes +90 degrees in a low load region below the first reference load value 22, that is, in the stratified operation region. In the middle load region between the second reference load value, that is, in the homogeneous lean burn region, the temperature is reliably -90 degrees, and in the high load region equal to or higher than the second reference load value 23, that is, in the homogeneous stoichiometric air-fuel ratio combustion region, it is reliably 0 degrees. As described above, the setting is made so as to change abruptly at the first and second reference load values 22 and 23.

In the second embodiment shown in FIG. 13, the transition period between the stratified combustion and the homogeneous lean combustion and the transition between the homogeneous lean combustion and the homogeneous stoichiometric air-fuel ratio combustion are performed so that the switching between the operation regions is performed smoothly. In FIG. 1, the angle of the tumble control valve 19 is
The change is more gradual than in the first embodiment shown in FIG. Specifically, the angle of the tumble control valve 19 is set to +90 degrees in an extremely low load region, and decreases continuously as the load increases from the extremely low load region to the middle load region. ,
The lower port portions 15a and 15b are both set so as to pass through the neutral position 24 at which the throttle is not throttled and to become -90 degrees at a medium load. Further, the angle of the tumble control valve 19 is continuously increased with an increase in the load from the middle load range to the high load range, and is set so as to become 0 degrees at an extremely high load. When the angle of the tumble control valve 19 is gently changed in this manner, it is possible to suppress a decrease in combustion performance due to an operation delay of the tumble control valve 19 in a transition period.

In the second embodiment, when the load is relatively high even in the stratified combustion operation range, the tumble control valve 19
Is slightly narrowed from the neutral position 24 to the upper port portion 15a. However, at such a relatively high load, the fuel injection amount increases and the time for the mixture to stay near the spark plug 2 becomes longer, so that There is almost no possibility of adversely affecting the combustion as in the comparative example shown in FIG.

At a relatively high load even in the homogeneous lean burn operation region, the angle of the tumble control valve 19 becomes close to 0 degrees, and the tumble flow is relatively weakened. Since the air amount increases, the turbulence in the flow in the cylinder increases, and the air-fuel mixture is appropriately diffused, there is no possibility that the air-fuel mixture will adversely affect combustion performance.

In the third and fourth embodiments shown in FIGS. 14 and 15, the angle of the tumble control valve 19 is changed according to not only the engine load but also the engine speed. That is,
When the engine speed is increased, the intake air flow rate is increased, so that a sufficient air-fuel mixture can be formed even at a low tumble intensity compared to when the engine speed is low, so that the tumble control is performed so that the optimal tumble intensity is obtained according to the engine speed. The operation of the angle of the valve 19 is controlled.

That is, in the third embodiment shown in FIG. 14, particularly in the transition period between stratified charge combustion and homogeneous lean combustion and the transition period between homogeneous lean combustion and homogeneous stoichiometric air-fuel ratio combustion, the tumble control valve 1
The angle characteristic of No. 9 is shifted to a lower load side as the engine speed increases. More specifically, the angle characteristic 26 at the time of predetermined high rotation is set to a state shifted to a lower load side than the angle characteristic 25 at the time of predetermined low rotation.

In the fourth embodiment shown in FIG. 15, the opening of the tumble control valve 19 is set to increase as the engine speed increases, that is, the angle of the tumble control valve 19 is set to decrease. ing. More specifically,
An angle characteristic 27 at a predetermined high rotation is set smaller than an angle characteristic 25 at a predetermined low rotation.

The present invention is not limited to the above-described example. For example, a general throttle valve having a different type from the above-mentioned butterfly valve may be used as the tumble control valve.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an intake control device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a direct injection internal combustion engine to which the intake control device is applied, showing a state before fuel injection in a stratified combustion operation.

FIG. 3 is a configuration diagram showing a state at the time of fuel injection in a stratified combustion operation of the internal combustion engine.

FIG. 4 is a configuration diagram showing a state at the time of ignition in a stratified combustion operation of the internal combustion engine.

FIG. 5 is a configuration diagram showing a state of an intake stroke in a homogeneous lean burn operation of the internal combustion engine.

FIG. 6 is a configuration diagram showing a state of a compression stroke in a homogeneous lean burn operation of the internal combustion engine.

FIG. 7 is a configuration diagram showing a state of a homogeneous stoichiometric air-fuel ratio operation of the internal combustion engine.

FIG. 8 is a configuration diagram showing a state of a stratified combustion operation of an internal combustion engine according to a comparative example.

FIG. 9 is a configuration diagram showing a state of an intake stroke in a homogeneous lean burn operation of an internal combustion engine according to a comparative example.

FIG. 10 is a configuration diagram showing a state of a compression stroke in a homogeneous lean burn operation of an internal combustion engine according to a comparative example.

FIG. 11 is a characteristic diagram illustrating a relationship between a flow coefficient and a tumble strength with respect to an inclination angle of an intake port.

FIG. 12 is map data showing the relationship between the engine load and the angle of the tumble control valve according to the first embodiment.

FIG. 13 is map data showing the relationship between the engine load and the angle of the tumble control valve according to the second embodiment.

FIG. 14 is map data showing the relationship between the engine speed and the engine load and the angle of the tumble control valve according to the third embodiment.

FIG. 15 is map data showing the relationship between the engine speed and the engine load and the angle of the tumble control valve according to the fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel injection valve 13 ... Cylinder 15 ... Intake port 15a ... Upper port part 15b ... Lower port part 17 ... Combustion chamber 18 ... Partition wall 19 ... Tumble control valve

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hirofumi Tsuchida Nissan Motor Co., Ltd. (2) Nissan Motor Co., Ltd. (72) Inventor Takashi Fukuda Takashicho 2 Takaracho, Kanagawa Ward, Yokohama City, Kanagawa Prefecture

Claims (5)

[Claims] A fuel injection valve for directly injecting fuel into a combustion chamber of each cylinder is disposed below an intake port, and
Stratified combustion in which fuel is injected in the compression stroke at low engine load, homogeneous lean combustion injecting fuel in the intake stroke at medium load, and homogeneous stoichiometric air-fuel combustion injecting fuel in the intake stroke at high load are performed. In a direct injection type internal combustion engine, a partition partitioning an intake port into an upper port portion and a lower port portion, and a tumble control valve for restricting the upper and lower port portions so as to regulate the forward tumble flow generated in the combustion chamber. When,
Control means for controlling the operation of the tumble control valve at least in accordance with the engine load, and throttle the lower port portion mainly during stratified combustion, and throttle the upper port portion mainly during homogeneous lean combustion, and mainly An intake control device for a direct injection internal combustion engine, wherein neither the upper port nor the lower port is set to be throttled during homogeneous stoichiometric air-fuel ratio combustion. 2. The butterfly control valve according to claim 1, wherein said tumble control valve is pivotally supported by said partition and is capable of holding one of an upper port portion and a lower port portion selectively at a throttle position and a neutral position substantially along the partition wall. The intake control device for a direct injection internal combustion engine according to claim 1, wherein the intake control device is a valve. 3. In a transition period between the stratified combustion and the homogeneous lean combustion and a transition period between the homogeneous lean combustion and the homogeneous stoichiometric air-fuel ratio combustion,
3. The intake control device for a direct injection internal combustion engine according to claim 1, wherein the throttle amounts of the upper and lower ports are set to change relatively slowly. 4. At least in the transition period between stratified combustion and homogeneous lean combustion and between transition between homogeneous lean combustion and homogeneous stoichiometric air-fuel ratio combustion, the angular characteristics of the tumble control valve with respect to the engine load are affected by an increase in the engine speed. The intake control device for a direct injection internal combustion engine according to any one of claims 1 to 3, wherein the intake control device is set to shift to a low load side accordingly. 5. The intake control device for a direct injection internal combustion engine according to claim 1, wherein the opening of the tumble control valve is set to increase as the engine speed increases. .