JP3671755B2 - Intake control device for direct injection internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a four-cycle direct injection internal combustion engine represented by a gasoline engine for automobiles, and in particular, a tumble control valve for adjusting a forward tumble flow generated in a combustion chamber is provided at an intake port of each cylinder. The present invention relates to an intake control device.
[0002]
[Prior art]
During medium and high loads, a homogeneous air-fuel ratio mixture is formed in the cylinder to perform so-called homogeneous combustion. In the low load range, a relatively rich mixture is formed only in a part of the cylinder, that is, in the vicinity of the spark plug. In-cylinder direct combustion that achieves both high output performance at medium and high loads by homogeneous combustion and improved fuel efficiency at low loads by stratified combustion Various injection-type internal combustion engines have been conventionally proposed.
[0003]
As an example, in a direct injection internal combustion engine described in Japanese Patent Application Laid-Open No. 9-256858, intake air having a partition that partitions an intake port into a forward tumble port portion and a reverse tumble port portion, and a control valve that throttles the forward tumble port portion. A control device is provided. Due to the shape of the forward and reverse tumble ports and the operation control of the control valve, during homogeneous combustion, the intake flow that flows into the cylinder descends along the cylinder wall on the exhaust side, and then the piston top surface and the cylinder wall surface on the intake side In the stratified combustion mode, the forward tumble port is throttled to reduce the intake flow that has flowed into the cylinder along the cylinder wall on the intake side. It is configured to stratify the air-fuel mixture by generating a reverse tumble flow that later flows along the piston top surface and the cylinder wall on the exhaust side and proceeds to the cylinder head side.
[0004]
As another example of the intake air control device that generates by switching between the forward tumble flow and the reverse tumble flow in this way, as described in JP-A-10-205338, the auxiliary intake air that energizes a part of the intake air flow. A technique for providing a pipe, or a technique for providing a tumble control valve for shielding a part of a passage in the vicinity of an opening on the combustion chamber side of an intake port as disclosed in Japanese Patent Laid-Open No. 10-212965. .
[0005]
Further, an intake control device for a direct injection internal combustion engine described in US Pat. No. 5,878,712 has a partition that partitions an intake port into an upper port part and a lower port part, and a tumble control valve that restricts the lower port part. In addition, a forward tumble flow is generated by the upper and lower passages of the intake port during homogeneous combustion, and a stronger forward tumble flow is generated by narrowing the lower port portion during stratified combustion.
[0006]
[Problems to be solved by the invention]
By the way, even in the above-described operation region in which homogeneous combustion is performed, homogeneous stoichiometric air-fuel ratio combustion near the stoichiometric air-fuel ratio is performed at high loads such as at fully-open output, while it is desirable mainly for the purpose of improving fuel efficiency at medium loads. The homogeneous lean combustion in which the air-fuel ratio is larger than the stoichiometric air-fuel ratio is performed.
[0007]
However, in the conventional intake control system for a direct injection internal combustion engine as described above, the rotational direction or strength of the tumble flow is switched between stratified combustion and homogeneous combustion, but homogeneous lean combustion and homogeneous stoichiometric air-fuel ratio combustion in homogeneous combustion. The rotational direction or intensity of the tumble flow is not switched between As a result, it is difficult to achieve both the flow enhancement at the time of homogeneous lean combustion and the securing of the air amount at the time of homogeneous stoichiometric combustion.
[0008]
More specifically, as shown in FIG. 11, the shape of the intake port, that is, the strength of the tumble flow (tumble ratio) with respect to the inclination angle θ and the flow rate (coefficient) of the intake air are generally in a contradictory relationship. As the amount of intake air is increased, the tumble strength tends to decrease. For this reason, if it is intended to sufficiently secure the maximum output at the time of engine high load, the tumble strength at the time of medium load is likely to be insufficient, the combustion at the time of homogeneous lean combustion may deteriorate, and sufficient fuel consumption improvement may not be obtained. .
[0009]
Therefore, in the configuration using both the forward tumble flow and the reverse tumble flow as in the above-mentioned JP-A-9-256858, JP-A-10-205338, and JP-A-10-212965, at the time of homogeneous lean combustion. In order to reinforce the tumble flow, the same reverse tumble flow as that in stratified combustion in which strong tumble flow is obtained can be applied during homogeneous lean combustion. However, in this case, the fuel spray falls along the cylinder wall surface on the intake side due to the reverse tumble flow descending along the cylinder wall surface on the intake side, and the combustible air-fuel mixture is unevenly distributed to the intake side at the ignition timing. It is difficult to obtain the combustion.
[0010]
On the other hand, in the configuration for adjusting the strength of the forward tumble flow as in US Pat. No. 5,878,712, in order to enhance the tumble flow in the homogeneous lean combustion, the same configuration as in the stratified combustion in which a strong forward tumble flow is obtained, It is conceivable to apply a configuration in which the lower port portion of the intake port is closed during homogeneous lean combustion. 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 is also lowered by the intake flow that descends near the center of the cylinder during the intake stroke, Although the air-fuel mixture diffuses 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 does not reach the entire combustion chamber. Therefore, the air-fuel mixture is unevenly distributed on the intake side as schematically shown in FIG. 10 at the ignition timing, and it is difficult to obtain a stable homogeneous lean combustion.
[0011]
The present invention has been made in view of such a problem, and it is possible to generate a stratified air-fuel mixture during stratified combustion, a homogeneous lean air-fuel mixture during homogeneous lean combustion, and a sufficient amount during homogeneous stoichiometric air-fuel ratio combustion. It is an object of the present invention to provide a novel direct-injection internal combustion engine intake control device that can ensure the air amount at a high level and can significantly improve the combustion performance.
[0012]
[Means for Solving the Problems]
The direct injection internal combustion engine according to the present invention has a stratified charge combustion in which a fuel injection valve for directly injecting fuel into the combustion chamber of each cylinder is disposed below the intake port, and fuel is injected in a compression stroke at a low load of the engine And 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.
[0013]
The intake control device according to the first aspect of the present invention includes a partition wall that partitions the intake port into an upper port portion and a lower port portion, and the upper and lower portions so as to adjust the forward tumble flow generated in the combustion chamber. A tumble control valve that throttles the port portion, and a control means that controls the operation of the tumble control valve according to at least the engine load. The lower port portion is mainly throttled during stratified combustion, and the upper port is mainly used during homogeneous lean combustion. It is characterized in that it is set so that the port portion is throttled and neither the upper port portion nor the lower port portion is mainly throttled during homogeneous stoichiometric air-fuel ratio combustion.
[0014]
With such a configuration, mainly during stratified combustion, the lower port portion is throttled, so the intake ratio from the upper port portion increases. As a result, the forward tumble flow generated in the combustion chamber is appropriately strengthened and becomes small in the center of the cylinder, which is suitable for stratification of the air-fuel mixture. More specifically, the fuel injected in the compression stroke is carried directly to the vicinity of the spark plug by the intake air flow (forward tumble flow) that flows along the crown surface of the piston and then rises toward the spark plug. A combustible air-fuel mixture is well formed near the spark plug at the ignition timing.
[0015]
Further, mainly at the time of homogeneous lean combustion, the upper port portion is throttled, so that the intake ratio from the lower port portion increases. As a result, the forward tumble flow generated in the combustion chamber is appropriately strengthened and swirled over the entire combustion chamber of the cylinder, which is suitable for generating a homogeneous lean air-fuel mixture. More specifically, the fuel injected in the intake stroke rides on the intake flow (forward tumble flow) introduced from the lower port near the fuel injection valve, diffuses throughout the combustion chamber, and burns at the ignition timing. A good homogeneous lean mixture is formed in the room.
[0016]
Furthermore, at the time of homogeneous stoichiometric air-fuel ratio combustion, since the upper and lower port portions are not restricted, it is possible to secure a sufficient intake air amount. In other words, the shape and dimensions such as the inclination angle of the intake port are set so as to ensure the maximum intake air amount at such a high load.
[0017]
As a result, according to the present invention, it is possible to achieve both a high level of improvement in the fuel efficiency improvement effect by stratified combustion and homogeneous lean combustion and an increase in output by homogeneous theoretical air-twist ratio combustion.
[0018]
As the tumble control valve, it is possible to use a general throttle valve. Preferably, as in the invention of claim 2, it is pivotally supported by the partition wall, and one of the upper port portion and the lower port portion is provided. One butterfly valve that can be held at a selectively throttled position and a neutral position substantially along the partition wall. In this case, since both the upper port portion and the lower port portion can be selectively restricted by one butterfly valve, the configuration and control can be simplified.
[0019]
In addition, in the transition period between stratified combustion and homogeneous lean combustion, or in the transition period between homogeneous lean combustion and homogeneous stoichiometric air-fuel ratio combustion, the throttle amount of the upper and lower ports may be changed rapidly. In order to suppress the deterioration of the combustion performance due to the operation delay of the tumble control valve in the transition period, the throttle amount of the upper and lower port portions changes relatively gradually in the transition period as in the invention of claim 3. Set to.
[0020]
Further, even when the engine load is the same, if the engine speed is relatively low, the flow rate of the intake air becomes low, and the tumble flow generated in the combustion chamber becomes relatively weak. On the contrary, when the engine rotational speed is high, the flow rate of the intake air increases and the tumble flow is relatively strengthened. Therefore, preferably, the throttle amount of the upper and lower port portions is changed according to the engine rotational speed so that an appropriate tumble flow corresponding to the engine rotational speed is obtained.
[0021]
Specifically, as in the invention of claim 5, the throttle amount of the upper and lower port portions is set to become smaller as the engine speed increases.
[0022]
Similarly, in the invention of claim 4, the angular characteristic of the tumble control valve with respect to the engine load is at least in the transition period between the stratified combustion and the homogeneous lean combustion and the transient period between the homogeneous lean combustion and the homogeneous stoichiometric air-fuel ratio combustion. It is set to shift to the low load side as the rotational speed increases.
[0023]
【The invention's effect】
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, and stratified combustion and homogeneous lean dilution can be achieved. The expansion of the fuel efficiency improvement effect by combustion and the improvement of the output by high load homogeneous theoretical air-twist combustion can be achieved at a high level.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which an intake control device according to the present invention is applied to a four-cycle automobile gasoline engine which is a direct injection internal combustion engine will be described in detail with reference to the accompanying drawings.
[0025]
As shown in FIG. 2, a plurality of cylinders 13 are arranged in series in the cylinder block 20, and the cylinder head 12 is fixed so as to cover the upper surface thereof. A piston 14 is slidably fitted in the cylinder 13, and a pent roof type combustion chamber 17 is formed above the piston 14. On the crown surface of the piston 14, a shallow dish-shaped recess 14a is provided.
[0026]
The cylinder head 12 is provided with an intake port 15 and an exhaust port 16 that open to the combustion chamber 17, and an intake valve 21 and an exhaust valve (not shown) that open and close the ports 15 and 16. The intake port 15 is set to an appropriate shape and size so as to generate forward tumble flows T1 to T3 flowing in the clockwise direction as shown in FIGS.
[0027]
At the top of each combustion chamber 17, the spark plug 2 is disposed at a substantially central position of the cylinder 13, and the plug tip faces the combustion chamber 17. In addition, the electromagnetic fuel injection valve 1 is disposed immediately below the intake port 15 in a posture in which the central axis is obliquely downward, so that fuel is directly injected into the combustion chamber 17. The leading end faces the combustion chamber 17.
[0028]
Each intake port 15 is provided with a thin plate-like partition wall 18 that divides the intake port 15 into an upper port portion 15a and a lower port portion 15b, and an upper port portion is provided at the upstream end of each partition wall 18. A butterfly valve type tumble control valve 19 that selectively throttles the lower port portion 15a and the lower port portion 15b 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. ing.
[0029]
FIG. 1 shows a schematic configuration of the intake control device. The engine control unit (ECU) 4 includes 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 that detects angles of the tumble control valve 19. Various sensors for detecting the operating state of the engine such as the valve angle sensor 11 are connected. The ECU 4 controls the operation of the tumble control valve driving device 3 that drives the tumble control valve 19 in addition to the fuel injection valve 1 and the spark plug 2 based on signals from these sensors. That is, the ECU 4 calculates a required fuel injection amount according to the engine speed, load, etc., generates a required fuel pressure by a fuel pump (not shown), outputs an injection valve drive signal to control fuel injection, and performs ignition. A signal is output to drive and control an ignition coil (not shown), and the ignition plug 2 is discharged to control ignition. The ECU 4 calculates the angle of the tumble control valve 19 mainly based on the engine load and the engine rotation speed, and controls the operation of the tumble control valve drive device 3.
[0030]
FIG. 7 shows a state of homogeneous stoichiometric air-fuel ratio performed at a high load such as a fully open output. At such a high load, in order to secure a sufficient intake air amount, the tumble control valve 19 is disposed at a neutral position along the partition wall 18, and the tumble control valve 19 determines which of the upper port portion 15 a and the lower port portion 15 b. Is set to an unthrottle state. As a result, the fuel injected in the intake stroke is uniformly diffused throughout the combustion chamber 17 by the forward tumble flow T3 of the intake flow introduced into the combustion chamber 17 from both the port portions 15a and 15b of the intake port 15. 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 at such a high load.
[0031]
2 to 4 show the state of the stratified combustion operation performed when the engine is under a low load, and sequentially show the states before and after fuel injection in the compression stroke. During such stratified combustion, the tumble control valve 19 is set to be rotated 90 degrees downward from the neutral position shown in FIG. 7 so as to restrict most of the lower port portion 15b. 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 when both the port portions 15a and 15b are not restricted as shown in FIG. As compared with the above, the tumble flow T <b> 1 generated in the combustion chamber 17 is effectively strengthened, and is relatively small that swirls around the center of the cylinder 13. Therefore, as shown in FIG. 3, the fuel injected in the compression stroke descends and flows along the crown surface of the piston 14 and then rides on the tumble flow T1 that rises toward the spark plug 2, and in the vicinity of the spark plug 2. As shown in FIG. 4, a good combustible air-fuel mixture is formed in the vicinity of the ignition plug in the vicinity of the compression top dead center that is the ignition timing. As a result, combustion substantially proceeds in the recess 14a, and good stratified combustion is realized.
[0032]
FIGS. 5 and 6 show the state of the homogeneous lean combustion operation performed at medium load of the engine, FIG. 5 shows the state of the intake stroke before the fuel injection is performed, and FIG. 6 shows the compression stroke after the fuel injection. Indicates the state. In such homogeneous lean combustion, contrary to the case of stratified combustion, the tumble control valve 19 is set to a position rotated 90 degrees above the neutral position. The tumble control valve 19 causes the upper port portion 15a to Most are squeezed. 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 effectively strengthened, and the inside of the cylinder 13 is also increased. It turns into a shape that swirls throughout. Therefore, as shown in FIG. 6, the fuel injected in the intake stroke is uniformly diffused on the tumble flow T2, and a good homogeneous lean air-fuel mixture is generated in the entire combustion chamber 17.
[0033]
In general, as shown in FIG. 11, the strength of the tumble flow generated by the intake port 15, that is, the tumble ratio, and the combustion chamber 17 from the intake port 15 according to the shape of the intake port 15, that is, the inclination angle θ. The flow rate coefficient of the intake air introduced to the air flow increases and decreases in a contradictory manner. Therefore, when the inclination angle of the intake port 15 is set so as to satisfy the required air amount at the time of high load as described above, the tumble flow component tends to be insufficient particularly during homogeneous lean combustion. However, in this embodiment, at the time of homogeneous lean combustion, the upper port portion 15a is throttled by the tumble control valve 19 so that the tumble flow is effectively strengthened. Therefore, the lack of tumble flow at the time of homogeneous lean combustion can be solved. it can.
[0034]
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 with reference to FIG. 10 will be described in detail using comparative examples.
[0035]
FIG. 8 shows an example in which the upper port portion 15a is narrowed by the tumble control valve 19 during stratified combustion, contrary to the embodiment shown in FIGS. In this case, the intake air mainly flows into the combustion chamber 17 through the lower port portion 15b, and a tumble flow T4 that rotates in the entire combustion chamber 17 is generated. For this reason, the fuel injected in the compression stroke is carried to the exhaust side on the intake flow (tumble flow T4) that swirls larger than the tumble flow T1. 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 short, and stratified combustion becomes unstable.
[0036]
In other words, in the present embodiment shown in FIGS. 2 to 4, the lower port portion 15 b is throttled by the tumble control valve 19, and the intake air is introduced into the combustion chamber 17 by the upper port portion 15 a 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 is not flowed to the exhaust side by the tumble flow immediately after entering the combustion chamber 17, and from the crown surface of the piston 14. The fuel spray is directly conveyed to the vicinity of the spark plug 2 by the tumble flow T1 toward the spark plug 2 side, so that good stratified combustion can be realized.
[0037]
9 and 10 show a comparative example in which the lower port portion 15b is narrowed 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 T <b> 5 formed in the combustion chamber 17 is a small one that turns 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. For this reason, at the ignition timing as shown in FIG. 10, the combustible mixture is unevenly distributed toward the intake side and is not diffused well throughout the combustion chamber 17, so that homogeneous lean combustion becomes unstable.
[0038]
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). The angle of the tumble control valve 19 is based on the neutral position where both the port portions 15a and 15b are fully opened as shown in FIG. 7, and the downward rotation direction in which the lower port portion 15b is throttled is the positive direction. The upward rotation direction in which the upper port portion 15a is throttled is the negative direction.
[0039]
In the first embodiment shown in FIG. 12, the angle of the tumble control valve 19 is surely +90 degrees in the low load region where the first reference load value 22 or less, that is, the stratified operation region, and the first reference load value 22 and the second reference load value In order to ensure -90 degrees in the medium load range between the load values, that is, in the homogeneous lean combustion region, and surely 0 degrees in the high load region above the second reference load value 23, that is, in the homogeneous stoichiometric air-fuel ratio combustion region, The first and second reference load values 22 and 23 are set so as to change rapidly.
[0040]
In the second embodiment shown in FIG. 13, in a transition period between stratified combustion and homogeneous lean combustion, and in a transition period between homogeneous lean combustion and homogeneous stoichiometric air-fuel ratio combustion, so that switching between the operation regions is performed smoothly. The angle of the tumble control valve 19 is changed more gently than in the first embodiment shown in FIG. Specifically, the angle of the tumble control valve 19 is set to +90 degrees in the extremely low load region, and continuously decreases as the load increases from the extremely low load region to the medium load region. , The lower port portions 15a and 15b are set to be -90 degrees through a neutral position 24 of 0 degrees where there is no restriction, and at a medium load. Further, the angle of the tumble control valve 19 is continuously increased as the load increases from the middle load range to the high load range, and is set to 0 degree at the time of extremely high load. When the angle of the tumble control valve 19 is gradually changed in this way, it is possible to suppress the deterioration of the combustion performance due to the operation delay of the tumble control valve 19 in the transition period.
[0041]
In the second embodiment, the tumble control valve 19 slightly throttles the upper port portion 15a from the neutral position 24 when the load is relatively high even in the stratified combustion operation region. Since the amount of fuel injection increases and the air-fuel mixture stays in the vicinity of the spark plug 2 also becomes longer, there is almost no risk of adversely affecting combustion as in the comparative example shown in FIG.
[0042]
Also, in the homogeneous lean combustion operation region, when the load is relatively high, the angle of the tumble control valve 19 is close to 0 degrees, and the tumble flow is relatively weakened. This increases the turbulence of the in-cylinder flow and appropriately diffuses the air-fuel mixture, so there is no possibility of adversely affecting the combustion performance.
[0043]
In the third and fourth embodiments shown in FIGS. 14 and 15, the angle of the tumble control valve 19 is changed not only according to the engine load but also according to the engine speed. That is, since the intake air flow rate increases when the engine speed increases, sufficient air-fuel mixture formation can be achieved even with a low tumble strength compared to when the engine speed is low, so that the optimum tumble strength is obtained according to the engine speed. The operation of the angle of the tumble control valve 19 is controlled.
[0044]
That is, in the third embodiment shown in FIG. 14, the angular characteristics of the tumble control valve 19 are determined in the engine rotation particularly in the transition period between stratified combustion and homogeneous lean combustion and in the transition period between homogeneous lean combustion and homogeneous stoichiometric air-fuel ratio combustion. As the speed increases, it is shifted to the low load side. More specifically, the angle characteristic 26 at a predetermined high rotation is set to be shifted to a lower load side than the angle characteristic 25 at a predetermined low rotation.
[0045]
In the fourth embodiment shown in FIG. 15, the opening of the tumble control valve 19 is increased as the engine speed increases, that is, the angle of the tumble control valve 19 is decreased. More specifically, the angle characteristic 27 at a predetermined high rotation is set smaller than the angle characteristic 25 at a predetermined low rotation.
[0046]
In addition, this invention is not limited to the example mentioned above, For example, the general throttle valve of a format different from said butterfly valve can also be used as a 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 type internal combustion engine to which the intake control device is applied, and showing a state before fuel injection in a stratified charge combustion operation.
FIG. 3 is a configuration diagram showing a state at the time of fuel injection in the stratified charge combustion operation of the internal combustion engine.
FIG. 4 is a configuration diagram showing a state at the time of ignition in the stratified charge combustion operation of the internal combustion engine.
FIG. 5 is a configuration diagram showing a state of an intake stroke in the homogeneous lean combustion operation of the internal combustion engine.
FIG. 6 is a configuration diagram showing a state of a compression stroke in the homogeneous lean combustion operation of the internal combustion engine.
FIG. 7 is a configuration diagram showing a state of homogeneous stoichiometric air-fuel ratio operation of the internal combustion engine.
FIG. 8 is a configuration diagram showing a state of stratified charge 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 combustion 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 combustion operation of an internal combustion engine according to a comparative example.
FIG. 11 is a characteristic diagram showing the relationship between the flow coefficient and the tumble strength with respect to the inclination angle of the 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 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 rotation speed and 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 19 ... Tumble control valve

Claims (5)

A fuel injection valve that directly injects fuel into the combustion chamber of each cylinder is arranged below the intake port, and stratified combustion in which fuel is injected during the compression stroke when the engine is under low load, and fuel is injected during the intake stroke during medium load. In a direct injection internal combustion engine in which homogeneous lean combustion to inject and homogeneous stoichiometric air-fuel ratio combustion in which fuel is injected in an intake stroke at a high load are performed,
A partition that divides the intake port into an upper port portion and a lower port portion, a tumble control valve that restricts the upper and lower port portions so as to adjust the forward tumble flow generated in the combustion chamber, and at least depending on the engine load Control means for controlling the operation of the tumble control valve,
The lower port is mainly throttled during stratified combustion, the upper port is throttled mainly during homogeneous lean combustion, and neither the upper or lower port is mainly throttled during homogeneous stoichiometric combustion. An intake control device for a direct injection internal combustion engine. The tumble control valve is a butterfly valve that is pivotally supported by the partition wall and can be held at a position for selectively restricting one of the upper port portion and the lower port portion and a neutral position substantially along the partition wall. 2. The intake control device for a direct injection internal combustion engine according to claim 1, wherein the intake control device is a direct injection type internal combustion engine. It is characterized in that the throttle amount at the upper and lower ports changes relatively slowly during the transition period between stratified combustion and homogeneous lean combustion, and during the transition period between homogeneous lean combustion and homogeneous stoichiometric air-fuel ratio combustion. The intake control apparatus for a direct injection internal combustion engine according to claim 1 or 2. At least in the transition period between stratified combustion and homogeneous lean combustion and in the transient period 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 reduced with increasing 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 air control device is set so as to shift to. The intake control apparatus for a direct injection internal combustion engine according to any one of claims 1 to 4, wherein the opening degree of the tumble control valve is set to increase as the engine speed increases.

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