JP2002155748A - In-cylinder injection spark ignition internal combustion engine - Google Patents

Abstract

(57) [Summary] In a cylinder injection type spark ignition internal combustion engine that switches between stratified combustion and homogeneous combustion, a strong intake flow in the intake stroke is reliably generated in the cylinder during homogeneous combustion.
It is an object of the present invention to prevent such a strong intake flow from being generated in a cylinder during stratified combustion, and to improve both homogeneous combustion and stratified combustion. SOLUTION: An opening area variable means (9, 9) capable of changing a substantial area of an in-cylinder opening of an intake port.
10), the substantial area of the in-cylinder opening is substantially maximized by the opening area variable means during the stratified combustion, and the substantial area of the in-cylinder opening is reduced to the set area by the opening area variable means during the homogeneous combustion.

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 internal combustion engine.

[0002]

2. Description of the Related Art An in-cylinder injection spark ignition internal combustion engine having a fuel injection valve for directly injecting fuel into a cylinder has a good ignitability at the time of ignition by injecting fuel in the latter half of a compression stroke. A combustible air-fuel mixture is formed only in the vicinity of the ignition plug to realize stratified combustion capable of burning a lean air-fuel mixture throughout the cylinder.

[0003] As described above, stratified combustion is effective in reducing the fuel consumption rate. However, the fuel injected in the compression stroke must be vaporized in a relatively short time until ignition, and a general in-cylinder injection spark is used. In an ignited internal combustion engine, stratified combustion is abandoned when the engine is at a high load requiring a large amount of fuel, and fuel is injected during an intake stroke to perform homogeneous combustion that forms a homogeneous mixture in a cylinder at the time of ignition. It has become.

As described above, in a general in-cylinder injection spark ignition internal combustion engine, stratified combustion and homogeneous combustion are switched and executed. In order to achieve good homogeneous combustion, it is necessary to generate a strong intake flow in the cylinder during the intake stroke. The strong intake flow allows the injected fuel to be sufficiently agitated and to form a good homogeneous mixture in the cylinder,
Even at the time of ignition, turbulence due to the intake air flow is maintained in the cylinder, and the combustion speed can be increased.

However, if a strong intake flow is generated in the cylinder during the intake stroke and the disturbance is maintained in the cylinder until ignition, this disturbance causes the formation of a combustible mixture near the spark plug during stratified combustion. Inhibiting the combustible mixture formed in the vicinity of the spark plug or dispersing the combustible air-fuel mixture before ignition makes it impossible to achieve good stratified combustion.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a direct injection type spark ignition internal combustion engine which switches between stratified charge combustion and homogeneous charge combustion. Therefore, it is necessary to prevent the generation of such a strong intake flow in the cylinder during stratified charge combustion, thereby improving both homogeneous combustion and stratified charge combustion.

[0007]

According to the first aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine comprising: a spark plug;
In a cylinder injection type spark ignition internal combustion engine which includes a fuel injection valve for directly injecting fuel into a cylinder and switches between stratified combustion and homogeneous combustion, a substantial area of a cylinder opening of an intake port is provided. The area of the opening in the cylinder is substantially maximized by the opening area variable means during the stratified combustion, and by the opening area variable means during the homogeneous combustion. A substantial area of the in-cylinder opening is reduced to a set area.

According to a second aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine according to the first aspect, wherein a large amount of intake air is provided even during the homogeneous combustion. When necessary, the substantial area of the in-cylinder opening is made larger than the set area by the opening area variable means.

According to a third aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine according to the first or second aspect, wherein the opening area variable means includes the opening area variable means. A partition that divides the intake port into at least two parts in the upstream longitudinal direction from the vicinity of the opening in the cylinder, and an intake control valve that can close one of two longitudinal parts of the intake port divided into two parts by the partition, During the stratified combustion, one of the longitudinal sections is opened by the intake control valve to substantially maximize the substantial area of the in-cylinder opening, and during the homogeneous combustion, the one longitudinal section is controlled by the intake control valve. By closing, the substantial area of the in-cylinder opening is reduced to the set area.

According to a fourth aspect of the present invention, there is provided an in-cylinder injection spark ignition internal combustion engine according to the first or second aspect, wherein the opening area variable means includes A mask wall formed at a part around the opening in the cylinder, and a lift amount variable mechanism of the intake valve, wherein the lift valve is opened by the lift amount variable mechanism so as to exceed the mask wall during the stratified combustion. To substantially maximize the substantial area of the in-cylinder opening, and during the homogeneous combustion, the lift valve is opened by the lift amount variable mechanism so that the intake valve does not exceed the mask wall. A characteristic area is reduced to the set area.

[0011]

FIG. 1 is a schematic longitudinal sectional view showing a first embodiment of a direct injection type spark ignition internal combustion engine according to the present invention. In the figure, 1 is an intake port, and 2 is an exhaust port. The intake port 1 communicates through the intake valve 3 and the exhaust port 2 communicates through the exhaust valve 4 into the cylinder.
Reference numeral 5 denotes a piston, reference numeral 6 denotes a spark plug disposed substantially at the center of the upper portion of the cylinder, and reference numeral 7 denotes a fuel injection valve for directly injecting fuel from the periphery of the upper portion of the cylinder into the cylinder. Fuel injection valve 7
Is disposed on the intake port 1 side where the temperature becomes relatively low due to the intake air flow in the combustion chamber in order to prevent fuel vapor.

FIG. 2 is a plan view of the piston 5. As shown in FIGS. 1 and 2, a concave cavity 8 is formed on the top surface of the piston 5. The cavity 8 contains the piston 5
It is unevenly distributed on the side of the fuel injection valve 7 on the top surface. Fuel injection valve 7
Has a slit-shaped injection hole, and injects fuel in a thin fan shape. In order to perform stratified combustion, fuel is injected into a cavity 8 formed on the top surface of the piston 5 at the end of the compression stroke, as shown in FIGS.
Although the fuel immediately after the injection indicated by oblique lines is in a liquid state, it proceeds along the bottom wall 8a of the cavity 8 and is vaporized until it is guided to the vicinity of the ignition plug 6 by the opposed side wall 8b of the cavity 8 facing the fuel injection valve. At the time of ignition, a combustible mixture having good ignitability indicated by dots is obtained. Thus, by forming a combustible mixture only near the ignition plug 6,
It is intended to realize stratified combustion that enables a lean air-fuel mixture to be burned as a whole in the cylinder.

The fan-shaped fuel spray having a small thickness spreads in the width direction as it travels along the bottom wall 8a of the cavity 8, so that it can absorb heat well from a wide range of the bottom wall 8a of the cavity 8. Can be. In the fuel that has spread in the width direction on the bottom wall 8a of the cavity 8, a velocity component directed upward is given to the central portion of the fuel by the opposing side wall 8b of the cavity 8, and the fuel goes toward the vicinity of the ignition plug 6, and both side portions of the fuel have:
The piston 8 collides at an acute angle with the opposed side wall 8b of the cavity 8 which is formed in an arc shape in a plan view of the piston, so that an upward velocity component and a velocity component toward the center are also applied, and the vicinity of the ignition plug 6 Head to.

Thus, the fan-shaped fuel spray having a small thickness is
Compared with the conventional conical fuel spray, a lump of combustible air-fuel mixture having a good degree of vaporization can be formed near the ignition plug 6. This makes it possible to increase the fuel injection amount during stratified combustion, and to expand stratified combustion with a low fuel consumption rate to a higher load side. However, the present invention does not include a fuel injection valve for realizing such a fan-shaped fuel spray as an essential component, and a fuel injection valve for realizing a conical or columnar fuel spray can also be used.

When a large amount of fuel is required due to a high engine load due to the fan-shaped fuel spray, it becomes difficult to inject fuel only at the end of the compression stroke. Combustion is performed.

In order to realize good stratified combustion, it is necessary to maintain a combustible mixture near the spark plug 6 at the time of ignition. Generally, when the intake valve 3 is opened during the intake stroke, intake air is introduced into the cylinder from the entire area around the in-cylinder opening of the intake port 1. As a result, from the exhaust port 2 side of the in-cylinder opening of the intake port 1, the intake air that attempts to turn in the cylinder in the vertical direction so as to descend mainly on the exhaust port 2 side of the cylinder bore and ascend on the intake port 1 side. At the same time as the flow is generated, from the non-exhaust port side of the in-cylinder opening of the intake port 1, let the cylinder bore turn vertically in the cylinder so as to descend mainly on the intake port 1 side and rise on the exhaust port 2 side. The intake air flow that occurs,
These two intake flows collide with each other in the cylinder. Also,
Since the substantial area of the in-cylinder opening in the intake port 1 for introducing the intake air into the cylinder is relatively large, the intake flow velocity when the intake air is introduced into the cylinder is generally slow.

As described above, since the two intake air flows are weak, they are easily eliminated during the intake stroke by colliding with each other, and the turbulence is maintained in the cylinder at least in the latter half of the compression stroke. In other words, turbulence in the cylinder prevents flammable air-fuel mixture during stratified charge combustion from being formed near the spark plug 6, or flammable air-fuel mixture formed near the ignition plug 6 is dispersed before ignition. There is no. Thus, good stratified combustion can be realized.

However, when the intake air is introduced with the substantial area of the in-cylinder opening substantially maximized as described above, a strong intake flow does not exist in the cylinder during the intake stroke as described above, and the fuel injection valve 7 does Since the injected fuel is not sufficiently stirred by the intake air flow and is not dispersed throughout the cylinder, it is impossible to form a good homogeneous air-fuel mixture.

This embodiment intends to improve both stratified combustion and homogeneous combustion. In the present embodiment, the intake valve 3 is not driven by a normal cam, but is driven by, for example, an electromagnetic or hydraulic actuator 10, and the actuator 10 can easily operate the stroke. It can be changed. The exhaust valve 4 may be driven by a normal cam.
Actuator 1 similar to actuator 10 for
1 is driven. In particular, the actuator 10 of the intake valve 3 includes a first operating position for realizing a large lift amount of the intake valve 3 as shown by a dashed line in FIG. 3, and a small operating position of the intake valve 3 as shown by a solid line in FIG. At least two-stage operation with the second operation position for realizing the lift amount is possible.

As shown in FIGS. 1 and 3, a mask wall 9 protruding downward is formed in a portion of the intake port 1 around the opening in the cylinder opposite to the exhaust port. In the first operating position of the actuator 10 described above, the intake valve 3 is opened so as to exceed the mask wall 9 by a large lift amount as shown in FIG. Thereby, the substantial area relating to the introduction of intake air at the in-cylinder opening of intake port 1 is maximized. In the second operating position of the actuator 10 described above, the intake valve 3 is opened by a small lift amount so that the intake valve 3 does not exceed the mask wall 9 as shown in FIG. Thereby, the substantial area related to the introduction of the intake air into the in-cylinder opening of the intake port 1 is the set area not covered by the mask wall 9.

FIG. 4 is a map for switching the lift amount of the intake valve 1 as described above. In this map,
The operating region is divided into three regions A, B, and C according to the engine speed and the engine load. The operation region A is an operation region in which both the engine speed and the engine load are relatively low, and is a region in which the above-described stratified combustion is performed. In this operation region A, the actuator 10 is in the first operating position. As a result, the intake valve 3 is opened beyond the mask wall 9 and the area of the in-cylinder opening of the intake port 1 is maximized, so that the intake valve 3 is introduced into the cylinder as in the general case described above. In addition, the intake air flow velocity is slowed down as a whole, and the two mainly generated intake air flows (indicated by dashed lines in FIG. 3) collide with each other when turning in the cylinder in the vertical direction and easily disappear. In addition, good stratified combustion is realized without adversely affecting the combustible mixture in the compression stroke.

The operation region B is an operation region in which both the engine speed and the engine load are relatively high, and it is difficult to inject a relatively large required fuel amount only in the latter half of the compression stroke. Therefore, this is an area where the above-described homogeneous combustion is performed. In this operation region B, the actuator 10 is in the second operation position. Thereby, the intake valve 3 is opened so as not to exceed the mask wall 9, and the area of the in-cylinder opening of the intake port 1 is reduced to the set area. As a result, the flow rate of the intake air introduced into the cylinder is increased, and as shown by the solid line in FIG. Is only the one that turns ascending. Thus, in the intake stroke, a vortex that swirls in the vertical direction due to a strong one-way intake air flow is formed in the cylinder, and the fuel injected during the intake stroke is sufficiently stirred to be dispersed throughout the cylinder, resulting in good uniformity. It is possible to form an air-fuel mixture. In addition, the strong intake vortex continues to swirl in the cylinder even during the compression stroke, causing turbulence in the cylinder at the time of ignition, so that the combustion speed of homogeneous combustion can be increased. Thus, good homogeneous combustion is realized. When the cooling water temperature is low, the fuel vaporization in the cylinder deteriorates. Therefore, the homogeneous combustion operation region B may be expanded to the low rotation and low load side. As a result, the stratified charge combustion region in which the required amount of fuel is relatively large is set as the homogeneous charge combustion region, and favorable homogeneous combustion with a strong intake flow is performed.

The operation region C is a region where the engine speed and the engine load are higher than the operation region B, and is a region in which homogeneous combustion is performed, but requires a large amount of intake air. In this operating region C, when the actuator 10 is in the second operating position, the substantial area of the in-cylinder opening of the intake port 1 is too small, resulting in insufficient intake. As a result, the actuator 10 is set to the first operating position, the intake valve 3 is opened so as to exceed the mask wall 9, and the area of the in-cylinder opening of the intake port 1 is maximized to prevent insufficient intake. I have. In this operation region, a large amount of intake air is introduced into the cylinder, so that the intake flow velocity becomes larger than that in the stratified charge combustion, so that more turbulence can be generated in the cylinder in the intake stroke than in the stratified charge combustion. As a result, it is possible to sufficiently stir the injected fuel to form a good homogeneous mixture.

In this embodiment, the actuator 10
Although the lift amount of the intake valve 1 is made variable in two steps, if it is possible to realize an intermediate lift amount of the intake valve 3 that is opened so that the intake valve 3 slightly exceeds the mask wall 9,
In the above-mentioned operation region C, the intake valve 3 may be opened with this intermediate lift amount. By doing so, the area of the in-cylinder opening of the intake port 1 is made larger than the set area in the operation region B, and the shortage of intake air can be eliminated. At this time, the above-described two intake flows are mainly generated in the cylinder. However, the intake flow which descends on the intake port 1 side of the cylinder bore and rises on the exhaust port 2 side to turn, has a high flow velocity. It has a small absolute amount of what it has, and is taken into the intake flow in the opposite direction where the absolute amount is large,
Lowering the exhaust port 2 side of the cylinder bore to intake port 1
A swirling flow rising on the side is formed. This swirling flow makes it possible not only to form a good homogeneous air-fuel mixture but also to improve the combustion speed due to in-cylinder turbulence at the time of ignition.

In the present embodiment, the mask wall is provided on the portion of the intake port 1 opposite to the exhaust port around the in-cylinder opening, but this is not a limitation of the present invention, and as shown in FIG. The wall 9 'may be provided on the exhaust port side portion around the in-cylinder opening of the intake port. If the intake valve 3 is opened so as to exceed the mask wall 9 'also by such a mask wall 9', a strong intake flow vortex is not generated in the cylinder as described above.
Good stratified combustion can be realized.

On the other hand, if the intake valve 3 is opened so as not to exceed the mask wall 9 ', a strong vertical moving down the intake port side of the cylinder bore and ascending the exhaust port side in the cylinder contrary to the above. A swirling flow is generated, and good homogeneous combustion can be realized. In the high rotation high load operation region C, as described above,
The area of the in-cylinder opening may be maximized, and the area of the in-cylinder opening may be made larger than the set area for normal homogeneous combustion. Combustion is feasible.

Also, as shown in FIG. 6, or in the opposite direction to that shown in FIG. 6, each half of the exhaust port side and the intake port side around the in-cylinder opening of the intake port is respectively surrounded. A mask wall 9 "may be provided. If the intake valve 3 is opened so as to exceed the mask wall 9" by such a mask wall 9 "as well, a strong intake flow is generated in the cylinder as described above. No vortex is generated, and good stratified combustion can be realized.

On the other hand, if the intake valve 3 is opened so as not to exceed the mask wall 9 ″, no intake air flow circulating in the cylinder is generated, but a high-speed intake air flow is introduced into the cylinder. Strong turbulence is generated in the cylinder, and a sufficiently homogenized homogeneous mixture is formed by sufficiently agitating the injected fuel, whereby good homogeneous combustion can be realized. In the region C, the area of the in-cylinder opening may be maximized as described above, and the area of the in-cylinder opening may be made larger than the set area during normal homogeneous combustion. And good homogeneous combustion can be realized.

FIG. 7 is a schematic vertical sectional view showing a second embodiment of the direct injection type spark ignition internal combustion engine according to the present invention. Only the differences from the first embodiment will be described below. In the present embodiment, the intake port 1 is divided into a first longitudinal portion 1a on the exhaust port 2 side and a second longitudinal portion on the side opposite to the exhaust port 2 by a partition wall 20 extending in the upstream longitudinal direction from the vicinity of the opening in the cylinder. 1b. The intake port extension 21 connected to the cylinder head is similarly divided into two by a partition, and an intake control valve 23 capable of closing the extension is disposed in an extension of the second longitudinal portion 1b. . The intake control valve 23 is driven by an actuator such as a step motor.

Since the partition wall 20 extends from the vicinity of the in-cylinder opening of the intake port 1, a notch for preventing contact when the intake valve 3 opens and closes is formed. The intake valve 3 and the exhaust valve 4 are driven by a normal cam, and the lift amount is not particularly variable.

In the present embodiment configured as described above, the intake control valve 23 is fully opened to open the second longitudinal portion 1b of the intake port 1 in the stratified combustion operation region A of the map shown in FIG. Thereby, the area of the in-cylinder opening of the intake port 1 is maximized, and a strong intake flow is not generated in the cylinder as in the first embodiment, and good stratified combustion can be realized.

On the other hand, in the homogeneous combustion operation region B, the intake control valve 23 is closed. Thereby, intake air is introduced into the cylinder only from the first longitudinal portion 1a of the intake port 1, which reduces the substantial area of the in-cylinder opening of the intake port 1 to a set area. Thereby, as described in FIG. 3 of the first embodiment, the intake air is introduced into the cylinder as a one-way high-speed intake flow indicated by a solid line, and descends on the exhaust port side of the cylinder bore and rises on the intake port side. Form a strong vertical swirling flow. Thereby, similarly to the first embodiment, good homogeneous combustion is realized.

In the homogeneous combustion operation region C where a large amount of intake air is required, if the intake control valve 23 is fully opened to maximize the substantial area of the in-cylinder opening of the intake port 1, the first longitudinal portion 1a and the Intake is introduced into the cylinder using both of the second longitudinal portions 1b, and the occurrence of insufficient intake is prevented. At this time, the intake air flow introduced into the cylinder from each of the first longitudinal direction portion 1a and the second longitudinal direction portion 1b has a relatively high flow velocity due to an increase in the intake air amount. And a good homogeneous mixture can be formed.

In the homogeneous combustion operation region C,
The intake control valve 23 may be opened halfway. By doing so, the area of the in-cylinder opening of the intake port 1 becomes larger than the set area during normal homogeneous combustion, and the intake air flows into the cylinder from both the first longitudinal portion 1a and the second longitudinal portion 1b. In addition to being able to eliminate the intake shortage, the intake flow introduced into the cylinder from the second longitudinal portion 1b has a high flow velocity but a small absolute amount. A large amount of intake flow introduced into the cylinder is taken in, and as a result, a vertical swirling flow is formed which descends on the exhaust port side of the cylinder bore and rises on the intake port side. As a result, a more favorable homogeneous mixture can be formed, and at the time of ignition, turbulence can be maintained in the cylinder to increase the combustion speed.

In this embodiment, the first longitudinal portion 1a for generating a strong intake flow during homogeneous combustion has a substantially semicircular cross section. However, the intake flow can be made smoother without reducing the sectional area. An oval or elliptical cross section may be used to enhance the intake flow. In this embodiment, the partition 20 separates the intake port 1 into the first longitudinal section 1a on the exhaust port side and the second longitudinal section 1a on the opposite side to the exhaust port.
b, and the second longitudinal portion 1b can be closed by the intake control valve 23, but this does not limit the present invention, and the first longitudinal direction 1b is replaced with the second longitudinal portion 1b. The part 1a may be made closable by an intake control valve. With such a configuration, the same intake flow as in the modification of the first embodiment shown in FIG. 5 can be generated in each operation region by opening and closing control of the intake control valve as described above. Can also be good.

In the second embodiment, the horizontal partition 2
Although the intake port 1 is divided into two in the longitudinal direction by 0, the intake port 1 may be divided into two by a vertical partition. By making one of the two divided longitudinal portions closable by the intake control valve, it is possible to generate an intake air flow similar to the modification of the first embodiment shown in FIG. Both combustions can be good. Including the second embodiment, it is free to further divide the intake port 1 thus divided into two in the longitudinal direction in the longitudinal direction.

[0037]

As described above, according to the direct injection type spark ignition internal combustion engine of the present invention, the engine is provided with the spark plug and the fuel injection valve for directly injecting the fuel into the cylinder. In the cylinder injection type spark ignition internal combustion engine, the opening area variable means for changing the substantial area of the in-cylinder opening of the intake port is provided. Thus, the substantial area of the in-cylinder opening is substantially maximized, and at the time of homogeneous combustion, the substantial area of the in-cylinder opening is reduced to a set area by the opening area variable means. As a result, at the time of stratified combustion, the intake air flow introduced into the cylinder through the in-cylinder opening of the intake port having the maximum area is generally slowed down due to the fact that the intake air amount is relatively small during the stratified combustion. No strong turbulence occurs in the inside, and good stratified combustion can be realized. On the other hand, during homogeneous combustion, since the area of the cylinder opening of the intake port is reduced to the set area, the intake air flow introduced into the cylinder through this cylinder opening becomes faster, and the intake air flows into the cylinder during the intake stroke. In order to cause strong turbulence, the injected fuel can be sufficiently stirred to form a sufficiently homogenized homogeneous mixture in the cylinder,
Good homogeneous combustion can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing a first embodiment of a direct injection type spark ignition internal combustion engine according to the present invention.

FIG. 2 is a plan view of a piston of the direct injection spark ignition internal combustion engine of FIG. 1;

FIG. 3 is a diagram illustrating a variable lift of an intake valve in the in-cylinder injection spark ignition internal combustion engine of FIG. 1;

FIG. 4 is a map used for variable lift control of an intake valve and open / close control of an intake control valve.

FIG. 5 is a bottom view of a cylinder head showing a modification of the in-cylinder injection spark ignition internal combustion engine of FIG. 1;

FIG. 6 is a bottom view of a cylinder head showing another modification of the in-cylinder injection spark ignition internal combustion engine of FIG. 1;

FIG. 7 is a schematic longitudinal sectional view showing a second embodiment of the direct injection type spark ignition internal combustion engine according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Intake port 2 ... Exhaust port 3 ... Intake valve 4 ... Exhaust valve 5 ... Piston 6 ... Spark plug 7 ... Fuel injection valve 10, 11 ... Actuator 20 ... Partition wall 23 ... Intake control valve

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02D 13/02 F02D 13/02 G 41/02 310 41/02 310A F term (reference) 3G023 AA07 AB03 AC05 AD05 AD06 AD09 AG01 3G092 AA01 AA06 AA09 AA10 DA03 DA14 DC02 DC06 DG08 EA01 EA02 EA11 HA06X HA11Z HA13X HE01Z 3G301 HA16

Claims (4)

[Claims] 1. An in-cylinder injection spark ignition internal combustion engine which includes a spark plug and a fuel injection valve for directly injecting fuel into a cylinder and switches between stratified combustion and homogeneous combustion. An opening area variable means for enabling a substantial area of the in-cylinder opening to be changed, and in the stratified combustion, the substantial area of the in-cylinder opening is substantially maximized by the opening area variable means; An in-cylinder injection spark ignition internal combustion engine, wherein a substantial area of the in-cylinder opening is reduced to a set area by the opening area variable means during homogeneous combustion. 2. The method according to claim 1, wherein when a large amount of intake air is required even during the homogeneous combustion, the substantial area of the in-cylinder opening is increased from the set area by the opening area variable means. 4. The in-cylinder injection spark ignition internal combustion engine according to claim 1. 3. The opening area variable means includes: a partition that divides the intake port into at least two portions in the upstream longitudinal direction from the vicinity of the in-cylinder opening; and two longitudinal portions of the intake port that are divided into two by the partition. An intake control valve that can be closed at one end, and in the stratified combustion, the intake control valve opens one of the longitudinal portions to substantially maximize the substantial area of the in-cylinder opening; 3. The in-cylinder injection system according to claim 1, wherein the intake control valve sometimes closes one of the longitudinal portions to reduce the substantial area of the in-cylinder opening to the set area. Spark ignition internal combustion engine. 4. The opening area variable means includes a mask wall formed around a part around the opening in the cylinder, and a lift amount variable mechanism of an intake valve. The intake valve is opened so as to exceed the mask wall to substantially maximize the substantial area of the in-cylinder opening, and the lift amount variable mechanism prevents the intake valve from exceeding the mask wall during the homogeneous combustion. And reducing the substantial area of the in-cylinder opening to the set area.
4. The in-cylinder injection spark ignition internal combustion engine according to claim 1.