JPH11257078A - Direct injection spark type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize the fuel send path during stratified combustion and allow the gas stream in the cylinder to be changed variably. SOLUTION: A swirl open/close valve 11 capable of creating a swirl within a combustion chamber 4 with the flow of intake air inclined to the left and right, and a tumble open/close valve 12 capable of creating a tumble within the combustion chamber 4 with the flow of intake air inclined up and down, are provided in an intake passage 8 of each cylinder, respectively, so as to be able to be operated independently. A fuel injection valve 10 is set so that the direction of injection is such that a spark plug 5 is not hit directly when there is no gas flowing in the combustion chamber 4 from a position below intake valves 6A, 6B. During stratified combustion, the injection fuel is inclined to the upper part of the combustion chamber from the tumble and fuel is sent to the spark plug 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection spark ignition type internal combustion engine in which fuel is directly injected from a fuel injection valve into a combustion chamber and ignited by a spark plug.

[0002]

2. Description of the Related Art As a conventional direct injection spark ignition type internal combustion engine,
For example, there is one disclosed in JP-A-6-81651. In this device, a fuel injection valve is provided below an intake port, a concave portion is provided on the intake side of a piston crown surface, and an ignition plug is provided on an extension of an edge of the concave portion on the center side of a combustion chamber. Then, the intake port is inverted tumble into the combustion chamber (that is, after the intake air flows downward along the cylinder wall across the upstream side of the injection direction line of the fuel injection valve, the intake port is bent at the concave portion of the piston crown surface, It is set so as to flow upward through the center of the combustion chamber across the downstream side of the injection direction line of the fuel injection valve to generate a gas flow that reaches the spark plug.

Here, when the load is low, fuel is injected in the compression stroke (stratified combustion), and when the load is high, fuel is injected in the intake stroke (homogeneous combustion). In compression stroke injection (stratified combustion),
The fuel injected from the fuel injection valve immediately rides on the intake flow, collides with the piston crown surface, and is transported while gradually vaporizing toward the spark plug by the reverse tumble generated in the cylinder.

[0004]

However, in such a conventional direct injection spark ignition type internal combustion engine, during the compression stroke injection (stratified combustion), the fuel colliding with the piston crown surface forms a liquid film, and the exhaust gas is exhausted. There is a problem that smoke in the inside and generation of HC may be caused, or a liquid film may be deposited as a deposit, and the detached deposit may cause a problem such as biting into an intake / exhaust valve.

The present invention has been made in view of the above-described conventional problems, and has as its object to optimize the fuel transport path during stratified combustion by making the in-cylinder gas flow variable.

[0006]

According to the first aspect of the present invention, there is provided a direct injection spark ignition type internal combustion engine in which fuel is directly injected from a fuel injection valve into a combustion chamber and ignited by a spark plug. Swirl enhancing means capable of generating swirl in the combustion chamber by deflecting the flow to the left and right,
And a tumble enhancing means capable of generating a tumble in the combustion chamber by deflecting the flow of the intake air in a vertical direction.

In the invention according to claim 2, the swirl enhancing means is provided in the intake passage for each cylinder and has a left-right asymmetric notch for communicating only a part of the intake passage cross section when the valve is closed. An opening / closing valve, wherein the tumble enhancing means is a tumble opening / closing valve provided in an intake passage for each cylinder and having a symmetrical notch for communicating only a part of the intake passage cross section when the valve is closed. Features.

In the invention according to claim 3, the swirl enhancing means and the tumble enhancing means are provided with a first on-off valve provided in an intake passage for each cylinder, and a first on-off valve branched from an upstream of the first on-off valve. It is characterized by including two symmetrical subports that merge downstream of the on-off valve and a second on-off valve provided in one of the subports. The invention according to claim 4 is characterized in that the injection direction of the fuel injection valve is set from the position below the intake valve so as not to directly hit the ignition plug in a state where there is no gas flow in the combustion chamber.

The invention according to claim 5 is characterized in that a circular concave portion having a center at a position eccentric to the intake side is provided in the piston crown surface. In the invention according to claim 6,
The piston crown is provided with a concave portion having a cylindrical surface having a center line in the front-rear direction of the engine. In the invention according to claim 7, a circular ball-shaped combustion chamber having a wall that is eccentric to the intake valve side and rises substantially below the ignition plug is formed on the piston crown surface, and exhaust gas is substantially discharged from below the ignition plug. 2 on the valve side
A cylindrical combustion chamber formed by a cylindrical surface having a longitudinal center line substantially parallel to a line connecting the centers of the two intake valves is formed.

[0010] In the invention according to claim 8, combustion control means for controlling stratified combustion in which fuel injection from the fuel injection valve is performed during a compression stroke and homogeneous combustion in which fuel injection from the fuel injection valve is performed during an intake stroke. And gas flow control means for controlling the operation of the swirl reinforcement means and the operation of the tumble reinforcement means. In the invention according to claim 9, the combustion control means causes stratified combustion to be performed when the operating condition of the engine is within a predetermined stratified combustion operation region, and the operating condition of the engine is within a predetermined homogeneous combustion operation region. The gas flow control means activates the tumble strengthening means when stratified combustion is performed by the combustion control means, and the swirl when homogeneous combustion is performed by the combustion control means. Activating the reinforcement means.

In the invention according to claim 10, the combustion control means causes stratified combustion to be performed when the operating condition of the engine is within a predetermined stratified combustion operation range, while the gas flow control means performs the combustion control. When the stratified combustion is performed by the means, and when the predetermined idle operation is performed, the swirl enhancing means is operated, and when the stratified combustion is performed by the combustion control means, and When the idle operation is not performed, the tumble enhancing means is operated.

[0012] In the invention according to claim 11, the combustion control means performs stratified combustion when the operating condition of the engine is within a predetermined stratified combustion operation region, while the gas flow control means performs the combustion control. When the stratified combustion is performed by the means, and when the operating condition of the engine is within a predetermined low-speed low-load region, the swirl enhancing means is operated, and the stratified combustion is performed by the combustion control means. And operating the tumble enhancing means when the operating condition of the engine is in an area other than the predetermined low-speed low-load area.

[0013] In the twelfth aspect, the combustion control means causes stratified combustion to be performed when the operating condition of the engine is within a predetermined stratified combustion operation range, while the gas flow control means controls the combustion control. When the stratified combustion is performed by the means, and when the operating condition of the engine is within a predetermined low rotation range, the swirl enhancing means is operated, and the stratified combustion is performed by the combustion control means. hand,
Further, when the operating condition of the engine is in an area other than the predetermined low rotation area, the tumble enhancing means is operated.

According to the invention of claim 13, in claim 10
In the invention according to claim 12, the combustion control means includes:
While causing the homogeneous combustion to be performed when the operating condition of the engine is in a predetermined homogeneous combustion operation region, the gas flow control means operates the swirl enhancing means when the combustion control means performs the homogeneous combustion. Features. According to a fourteenth aspect of the present invention, in the ninth to thirteenth aspects, the gas flow control means is configured to perform stratified combustion by the combustion control means, and to complete the warm-up of the engine. When not in operation, the swirl enhancing means is forcibly activated.

[0015]

According to the first aspect of the present invention, since the swirl reinforcement means and the tumble reinforcement means are provided, the in-cylinder gas flow is changed depending on the operating conditions of the engine, and the fuel transport path during stratified combustion is provided. Can be controlled. Further, by using the tumble flow, stratified combustion can be performed without providing a concave portion on the piston crown surface, and by using the swirl flow, mixing of the air-fuel mixture can be controlled.

According to the second aspect of the present invention, by using the on-off valves having different notches as the swirl reinforcing means and the tumble reinforcing means, the flow form can be changed only by changing the notch shape. Therefore, deployment to other engines is easy, and the flow strength can be easily controlled by controlling the opening degree. According to the third aspect of the present invention, swirl can be generated by introducing intake air from one subport, and tumble can be generated by introducing intake air from two subports, and more powerful flow can be generated. It becomes possible.

According to the fourth aspect of the present invention, since the injection direction of the fuel injection valve is set so as not to directly hit the spark plug, it is possible to avoid direct hit of the droplet fuel to the spark plug in a cold state. According to the invention according to claim 5, by providing a circular concave portion having a center at a position eccentric to the intake side of the piston crown surface, when swirl is generated during stratified combustion,
By injecting fuel into the piston concave portion, the vaporized air-fuel mixture can be transported to the ignition plug, and good stratified combustion can be performed, thereby avoiding smoldering of the ignition plug at the time of a cold start or the like.

According to the sixth aspect of the invention, by providing the piston crown with a concave portion having a cylindrical surface having a center line in the front-rear direction of the engine, the tumble can be effectively preserved, and the tumble can be effectively prevented. Even when the flow is weak as described above, it is possible to ensure the transportation of the fuel to the spark plug. According to the invention of claim 7, by forming the ball-type combustion chamber for swirl storage and the cylindrical combustion chamber for tumble storage on the piston crown surface, good performance is exhibited in all areas of engine operation. It is possible to

According to the eighth aspect of the present invention, by providing the combustion control means for controlling the stratified combustion and the homogeneous combustion, and the gas flow control means for controlling each operation of the swirl reinforcement means and the tumble reinforcement means, It can be controlled by the optimal combination. According to the invention according to claim 9, in the stratified combustion operation region, stratified combustion is realized by the air guide concept that guides fuel spray around the spark plug by forward tumbling, and in the homogeneous combustion operation region, stabilization of combustion is performed by swirl. By this, good stratified combustion and good homogeneous combustion can be realized.

According to the tenth aspect of the present invention, when realizing stratified charge combustion by forward tumbling, it may be difficult to guide spray around the spark plug in a region where the in-cylinder flow is weak. In the area, swirl and tumble are switched in accordance with the engine operating state, and the swirl performs stratified combustion by the swirl concept that guides fuel spray around the spark plug to achieve stratified combustion and stratified combustion by the air guide concept (forward tumbling). Good stratification can be achieved in the entire stratified combustion operation region by properly using the swirl concept. In particular, by using the swirl concept only during idling operation in the stratified combustion operation region, the depth of the swirl storage recess (ball-type combustion chamber) can be improved. The depth can be made shallow, and sufficient performance can be maintained even in the homogeneous combustion operation region such as when fully opened.

According to the eleventh aspect of the present invention, the swirl concept is used only in the low rotation speed and low load region particularly in the stratified combustion operation region, so that the depth of the swirl storage recess (ball type combustion chamber) can be reduced. Sufficient performance can be maintained even in the homogeneous combustion operation region such as when fully opened. According to the twelfth aspect of the present invention, the swirl concept is used only in the low rotation speed region particularly in the stratified combustion operation region. Sufficient performance can be maintained even in the homogeneous combustion operation range.

According to the thirteenth aspect, in the case of homogeneous combustion, good uniform combustion can be realized by stabilizing combustion by swirling. According to the invention according to claim 14, in the case of stratified charge combustion, by switching so as to generate swirl at the time of cold start and to generate tumble after completion of warming-up, the ignition plug of the droplet fuel at the time of cold time To avoid direct hits.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic plan view and a longitudinal sectional view of an engine showing a first embodiment of the present invention. In FIG.
1 is a cylinder head, 2 is a cylinder block, 3 is a piston, and 4 is a combustion chamber formed by these.

Top side of combustion chamber 4 (cylinder head 1 side)
Is provided with an ignition plug 5 at substantially the center, and two intake valves 6A and 6B on one side and two exhaust valves 7A and 7B on the other side so as to surround the ignition plug 5. The intake air is guided by an intake passage 8 for each cylinder, and the intake passage 8 branches into two left and right intake ports in the cylinder head 1 and is taken into the combustion chamber 4 from each intake valve 6A, 6B. . The exhaust gas is discharged from the exhaust valves 7A and 7B to the exhaust passage 9.

The fuel injection valve 10 is directed from the lower position between the intake valves 6A and 6B into the combustion chamber 4, and the injection direction is such that the fuel spray is applied to the ignition plug 5 without gas flow.
Is directed on an extension line below the spark plug 5 so as not to hit directly. Here, the intake passage 8 for each cylinder
And a swirl on-off valve 11 as a swirl reinforcing means.
And a tumble on-off valve 12 as tumble reinforcing means are provided in series.

The swirl on-off valve 11 is a butterfly valve, and has a notch (asymmetrical notch) 11a in the upper half of the valve body as shown in FIG. 2 (a). Thus, when the valve is closed, only the upper half of the cross section of the intake passage is communicated, and swirl can be generated in the combustion chamber 4. The tumble on-off valve 12 is also a butterfly valve, but is provided with a notch (a symmetrical notch) 12a in the upper part of the valve body as shown in FIG. 2B. Thus, when the valve is closed, only the upper part of the cross section of the intake passage is communicated, and a tumble can be generated in the combustion chamber 4.

This tumble is a forward tumble as shown in FIG. That is, the intake air is supplied to the combustion chamber 4
Flows along the upper surface side (cylinder head 1 side) of the fuel injection valve 10, then flows across the downstream side of the injection direction line of the fuel injection valve 10, and reverses at the crown surface of the piston 3. The gas flow flows across the upstream side of the injection direction line and reaches the spark plug 5.

As shown in FIG. 3, the swirl on-off valve 11 and the tumble on-off valve 12 are driven by actuators 13 and 14 such as motors, respectively. 15 controls the engine according to the engine operating conditions. Here, the control unit 1
5 is a function as combustion control means for controlling stratified combustion in which fuel injection from the fuel injection valve 10 is performed during a compression stroke and homogeneous combustion in which fuel injection from the fuel injection valve 10 is performed during an intake stroke. It has a function as gas flow control means for controlling the operation of the swirl enhancing means (the swirl on-off valve 11) and the operation of the tumble enhancing means (the tumble on-off valve 12).

Basically, as shown in FIG. 4, in the stratified combustion (stratified lean combustion) operation region at a low rotation speed and a low load, the in-cylinder gas flow is set to a strong tumble according to the engine speed and the load. The tumble on-off valve 12 is closed. However,
Based on the signal from the water temperature sensor, the switching is performed such that the swirl on-off valve 11 is closed to generate swirl during cold start, and the tumble on-off valve 12 is closed after warm-up is completed to generate tumble.

In the homogeneous lean combustion operation region slightly higher than this region, the swirl on-off valve 11 is closed so that the in-cylinder gas flow is swirled. In addition, homogeneous stoichiometry (or rich) at high rotation and high load other than these
In the combustion operation region, the tumble on-off valve 12 is closed at least to a half-open state so that the in-cylinder gas flow is weakly tumbled.

FIG. 5 is a schematic view showing the behavior of fuel due to tumble during stratified combustion in the first embodiment. During stratified combustion (during compression stroke injection), the tumble on-off valve 12 is closed to make the in-cylinder gas flow strong tumble. The fuel injected from the fuel injection valve 10 in the compression stroke is deflected to the upper side of the combustion chamber 4 by the tumble that inverts at the crown surface of the piston 3 and then to the upper side of the combustion chamber 4, and spreads to the spark plug 5 while expanding. Reached and ignited. Therefore, since the fuel does not pass through the crown surface of the piston 3, almost no liquid film is formed, and the generation of smoke, HC, and deposits can be suppressed.

However, at the time of cold start, the swirl flow is switched to the strong tumble after the warm-up is completed. This allows
The mixture distribution at the time of starting the engine is improved, and stratified combustion can be performed without smoldering the ignition plug 5. In this embodiment, since the form of the flow can be changed by changing the shape of the notch, it can be easily developed in other engines.
In addition, the flow strength can be easily controlled by controlling the opening degree.

FIG. 6 is a longitudinal sectional view of an engine showing a second embodiment of the present invention, and FIG. 7 is a plan view of a piston in this case. In the second embodiment, a circular concave portion (ball-type combustion chamber) 16 having a center at a position eccentric to the intake side is provided on the crown surface of the piston 3. Others are the same as the first embodiment.

FIG. 8 is a schematic diagram showing the behavior of fuel due to swirl during stratified combustion in the second embodiment.
As shown in FIG. 8, at the time of cold start in stratified combustion, the swirl on-off valve 11 is closed, and the inside of the combustion chamber 4,
A swirl is generated in the recess 16 in the crown surface of the
By injecting fuel from the fuel injection valve 10 into the inside, the fuel whose vaporization is promoted by the crown surface of the piston 3 can be transported to the ignition plug 5 by the action of the swirl flow formed in the concave portion 16 and smolder. And stratified combustion becomes possible.

FIG. 9 is a longitudinal sectional view of an engine showing a third embodiment of the present invention, and FIG. 10 is a plan view of a piston in this case.
In the third embodiment, a concave portion (cylindrical combustion chamber) having a cylindrical surface having a center line in the front-rear direction of the engine is provided in the crown surface of the piston 3.
17 are provided. Others are the same as the first embodiment.

Thus, the tumble formed in the cylinder can be efficiently stored until the latter half of the compression stroke.
Even at low engine speed, the fuel can be deflected upward by tumble and transported to the ignition plug 5, and stable stratified combustion can be performed. FIG. 11 is a longitudinal sectional view of an engine showing a fourth embodiment of the present invention. In the fourth embodiment, on the crown surface of the piston 3,
A circular shallow plate-shaped ball-shaped combustion chamber 18 having a wall 18a that is eccentric to the intake valves 6A and 6B and rises substantially below the ignition plug 5.
And the exhaust valves 7A, 7B
A cylindrical combustion chamber 19 formed by a cylindrical surface having a longitudinal center line substantially parallel to a line connecting the centers of the two intake valves 6A and 6B toward the side. Others are the same as the first embodiment.

As described above, by forming the ball-type combustion chamber 18 for swirl storage and the cylindrical combustion chamber 19 for tumble storage on the crown surface of the piston 3, good performance can be obtained in all regions of engine operation. It is possible to demonstrate. FIG.
FIG. 9 is a schematic plan view and a longitudinal sectional view of an engine showing a fifth embodiment of the present invention. In the fifth embodiment, a first on-off valve 21 is provided in the intake passage 8 for each cylinder. Further, two symmetrical subports 22A and 22B are provided which branch upward from the upstream side of the first opening / closing valve 21 and join the downstream side of the first opening / closing valve 21 (directly upstream of the intake valves 6A and 6B). A second on-off valve 23 is provided in the middle of one of the subports 22B. These correspond to the swirl reinforcement means and the tumble reinforcement means.

In this case, by closing the second on-off valve 23 with the first on-off valve 21 closed, the sub port 2 is closed.
By introducing the intake air asymmetrically from only 2A, swirl can be generated. By opening the second on-off valve 23 with the first on-off valve 21 closed, intake air is introduced symmetrically from both subports 22A and 22B, and the flow of intake air is increased and decreased by the subports 22A and 22B. By deflecting in the direction, a tumble can be generated.

As a result, a stronger gas flow can be generated in the cylinder, the fuel can be deflected upward by tumble and transported to the ignition plug 5 even at a low engine speed, and more stable stratified combustion can be achieved. . In the fifth embodiment, a recess (ball-type combustion chamber) 16 similar to that of the second embodiment is provided on the crown surface of the piston 3, but a recess 17 similar to that of the third embodiment.
(Cylindrical combustion chamber) may be provided, or a ball-type combustion chamber 18 and a cylindrical combustion chamber 19 may be provided as in the fourth embodiment. Of course, as in the first embodiment, the concave portion may not be provided.

Next, another embodiment in which swirl and tumble are switched according to the engine operating conditions will be described.
In the control map shown in FIG. 4, a tumble is generated in the stratified combustion (stratified lean combustion) operation region (an air guide concept by strengthening forward tumbling), but the engine operation is performed in the stratified combustion operation region. The swirl and the tumble may be switched according to the state.

When realizing stratified charge combustion by forward tumbling, it may be difficult to guide the spray around the spark plug in a region where the in-cylinder flow is weak. Therefore, as shown in FIGS. In the range, swirl and tumble are switched according to the engine operating state, and stratified combustion by the swirl concept on the low rotation and low load side, and stratified combustion by the air guide concept (forward tumble) on the high rotation and high load side. Good stratified combustion can be achieved over the entire combustion operation range. In addition, it is possible to make the recess (ball-type combustion chamber) for swirl storage formed in the piston crown surface shallow, so that sufficient performance can be maintained even in the homogeneous combustion operation range (flow and turbulence in the cylinder during homogeneous combustion). Can be secured sufficiently), and the full-open performance is also improved.

In the control map shown in FIG. 13, stratified combustion is realized by swirl only in the idling operation state in the stratified combustion operation region. In the control map shown in FIG. 14, stratified combustion is realized by swirl in a low-speed low-load region in a stratified combustion operation region. FIG.
In the control map shown in FIG. 5, stratified combustion is realized by swirl in the low rotation speed region in the stratified combustion operation region.

[Brief description of the drawings]

FIG. 1 is a schematic plan view and longitudinal sectional view of an engine showing a first embodiment of the present invention.

FIG. 2 is a view showing cutout shapes of a swirl on-off valve and a tumble on-off valve.

FIG. 3 is a schematic diagram of a control system.

FIG. 4 is a diagram showing a control map;

FIG. 5 is a schematic diagram showing the behavior of fuel due to tumble during stratified combustion.

FIG. 6 is a longitudinal sectional view of an engine showing a second embodiment of the present invention.

FIG. 7 is a plan view of the same piston.

FIG. 8 is a schematic diagram showing the behavior of fuel due to swirl during stratified combustion.

FIG. 9 is a longitudinal sectional view of an engine showing a third embodiment of the present invention.

FIG. 10 is a plan view of the piston of the above.

FIG. 11 is a longitudinal sectional view of an engine showing a fourth embodiment of the present invention.

FIG. 12 is a schematic plan view and longitudinal sectional view of an engine showing a fifth embodiment of the present invention.

FIG. 13 is a diagram illustrating another example of the control map.

FIG. 14 is a diagram showing another example of the control map.

FIG. 15 is a diagram showing another example of the control map.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Cylinder block 3 Piston 4 Combustion chamber 5 Spark plug 6A, 6B Intake valve 7A, 7B Exhaust valve 8 Intake passage 9 Exhaust passage 10 Fuel injection valve 11 Swirl on-off valve 11a Notch 12 Tumble on-off valve 12a Notch DESCRIPTION OF SYMBOLS 13 Actuator 14 Actuator 15 Control unit (combustion control means and gas flow control means) 16 Recess (ball type combustion chamber) 17 Recess (cylindrical combustion chamber) 18 Ball type combustion chamber 19 Cylindrical combustion chamber 21 First on-off valve 22A, 22B Sub port 23 Second on-off valve

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02B 23/10 F02B 23/10 Z 31/02 31/02 L F02D 41/02 325 F02D 41/02 325A 325G 41/04 335 41 / 04 335C 43/00 301 43/00 301J 301U F02F 3/26 F02F 3/26 A (72) Inventor Takashi Aoyama 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture Nissan Motor Co., Ltd. (72) Inventor Waki Aramaki Nissan Motor Co., Ltd. (72) Inventor Yuichi Iriya Nissan Motor Co., Ltd., 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa

Claims (14)

[Claims] In a direct injection spark ignition type internal combustion engine in which fuel is directly injected into a combustion chamber from a fuel injection valve and ignited by an ignition plug, swirl is generated in the combustion chamber by deflecting a flow of intake air in a left-right direction. A direct-injection spark ignition internal combustion engine, comprising: a swirl enhancing means capable of generating a tumble in a combustion chamber by deflecting a flow of intake air in a vertical direction. 2. The swirl on-off valve according to claim 1, wherein the swirl enhancing means is provided in an intake passage for each cylinder and has a left-right asymmetric notch for communicating only a part of the intake passage cross section when the valve is closed. 2. A tumble on / off valve provided in an intake passage for each cylinder and having a symmetrical notch for communicating only a part of the cross section of the intake passage when the valve is closed. A direct-injection spark ignition internal combustion engine as described. 3. The swirl enhancing means and the tumble enhancing means, a first on-off valve provided in an intake passage for each cylinder, and a branch from an upstream side of the first on-off valve to join a downstream side of the first on-off valve. 2. The direct-injection spark ignition type internal combustion engine according to claim 1, wherein the engine includes two symmetrical subports and a second on-off valve provided in one of the subports. 4. The fuel injection valve according to claim 1, wherein the injection direction of the fuel injection valve is set so as not to directly hit the ignition plug in a state where there is no gas flow in the combustion chamber from a position below the intake valve. A direct injection spark ignition type internal combustion engine according to one of the preceding claims. 5. A direct-injection spark according to claim 1, wherein a circular concave portion having a center at a position eccentric to the intake side is provided in the piston crown surface. Ignition internal combustion engine. 6. A direct-injection spark ignition according to claim 1, wherein a concave portion having a cylindrical surface having a center line in the front-rear direction of the engine is provided in the piston crown surface. Type internal combustion engine. 7. A circular ball-shaped combustion chamber having a wall eccentric to the intake valve side and rising substantially below the ignition plug is formed on the piston crown surface, and substantially from below the ignition plug to the exhaust valve side. 5. A cylindrical combustion chamber formed by a cylindrical surface having a longitudinal center line substantially parallel to a line connecting the centers of the two intake valves. 4. A direct-injection spark ignition internal combustion engine according to claim 1. 8. A combustion control means for controlling stratified combustion in which fuel injection from the fuel injection valve is performed in a compression stroke and homogeneous combustion in which fuel injection from the fuel injection valve is performed in an intake stroke. The direct-injection spark ignition type internal combustion engine according to any one of claims 1 to 7, further comprising: gas flow control means for controlling an operation and an operation of the tumble enhancing means. 9. The combustion control means causes stratified combustion to be performed when the operating condition of the engine is within a predetermined stratified combustion operation range. While performing combustion, the gas flow control means activates the tumble reinforcement means when stratified combustion is performed by the combustion control means, and activates the swirl reinforcement means when homogeneous combustion is performed by the combustion control means. 9. The direct injection spark ignition type internal combustion engine according to claim 8, wherein the engine is operated. 10. The combustion control means performs stratified combustion when the operating condition of the engine is within a predetermined stratified combustion operation range, while the gas flow control means performs stratified combustion by the combustion control means. And when the predetermined idle operation is performed, the swirl enhancing means is operated,
9. The direct-injection spark ignition internal combustion engine according to claim 8, wherein the tumble enhancing means is operated when stratified combustion is performed by the combustion control means and when a predetermined idle operation is not performed. organ. 11. The combustion control means causes stratified combustion to be performed when the operating condition of the engine is within a predetermined stratified combustion operation range, while the gas flow control means performs stratified combustion by the combustion control means. And when the operating condition of the engine is within a predetermined low-speed low-load region, the swirl enhancing means is operated, and the stratified combustion is performed by the combustion control means, and 9. The tumble enhancing means is operated when an operating condition of the engine is in an area other than the predetermined low-speed low-load area.
A direct-injection spark ignition internal combustion engine as described. 12. The combustion control means causes stratified combustion to be performed when the operating conditions of the engine are within a predetermined stratified combustion operation range, while the gas flow control means performs stratified combustion by the combustion control means. And when the operating condition of the engine is within a predetermined low rotation range, the swirl enhancing means is operated, and the stratified combustion is performed by the combustion control means, and 9. The direct-injection spark ignition type internal combustion engine according to claim 8, wherein the tumble enhancing means is operated when an operating condition is in a region other than the predetermined low rotation region. 13. The combustion control means causes homogeneous combustion to be performed when the operating condition of the engine is in a predetermined homogeneous combustion operation range, while the gas flow control means performs homogeneous combustion by the combustion control means. The direct-injection spark ignition type internal combustion engine according to any one of claims 10 to 12, wherein the swirl enhancing means is sometimes activated. 14. The gas flow control means forcibly activates the swirl enhancement means when stratified combustion is performed by the combustion control means and when the warm-up of the engine is not completed. The direct-injection spark ignition type internal combustion engine according to any one of claims 9 to 13, wherein: